Yes, it's a tough job to do that effectively, without using math. Using ohm's law and the simple equations for power would make it easier to see the relationships, and the resulting explanations. Paul's got his work cut out for himself in not using math to explain things.
If you don't want to lose bass don't lend it to anybody. I lent my G&L to a guy back in the 90's. He left town in the "middle of the night" and I never saw my bass again. I had lost all of my bass. Thanks for the video Paul.
Thank you, Paul. I wish you did explain those technical matters with a whiteboard. I can't see well in your note. We love to hear your technical class more to understand the science of audio to try to recreate music aculeate in the studio.
I like to describe it using a teeter totter analogy where the left side of the teeter totter represents a preamp and the right side represents an amplifier and the distance from either end to the pivot represents impedance. When the pivot is centered between the two ends of the teeter totter, the distances from either end to the pivot are equal. The impedances are equal and both ends of the teeter totter move up and down the same distance, a ratio of 1:1. As you move the pivot from the center towards the preamp side, the distance between the pivot and the preamp become shorter (impedance decreases), while the distance from the pivot to the amp side becomes longer, (impedance increases). At the same time the distance that the preamp end moves up and down decreases compared to the distance that the amp side moves up and down which increases. The ratio can increase from 1:1, 1:10, 1:100 to the limits of the amp where it starts to distort.
The times where matching of input impedance to output impedance for line signals is long gone for most equipment. The output impedance is about 10e2 ohms while the input impedance is about 30kohm-50kohm range. In the days of old telephone centrals the input and output impedance was matched to 600 ohm. The matching of impedances is much more crucial when matching microphone impedance to microphone preamp.
Hi Paul. Tricky question to answer with voltage divider theory. I understand you want to keep it simple but there are other factors here other than the fact that the signal is being attenuated. I doubt a power amp will create back EMF to a pre-amp like a speaker will present to the output of a power amp. A Power amp dont have a reactive (non linear) input load especially at low frequencies. As the power amp input stage is biased into class A it will not (or should not at least if a good design) have a significant dependance on source impedance, especially some characteristic that creates additional voltage drops at bass frequencies only. Often a resistor is placed in series with the input of a power amp to limit HF bandwidth. This does not ruin the bass performance. Most power amps will even sound acceptable with a 10k passive volume pot and that is how integrated amps are often made. One issue with high pre amp output impedance is the interaction with long cable leads, also including input capacitance if a power amp. With short interconnects 1000 Ohms should not be an issue. With very long interconnects a lower output inpedance like 200R is better. It is most likely that a pre amp with lower output impedance is better designed and will stay in class A for all typical cable and power amp input impedance. This gives a more transparent natural sound.
Thanks so much for the detailed explanation. I recently bought a Schiit Saga S (o/p impedance 180 ohms) feeding into a Crown XLS 1002 (i/p impedance not specified but allegedly 🙂10K SE) and was feeling a loss of bass - maybe time to change the amplifier too
How to avoid losing bass? Unplug any power amplifiers, subwoofers or speakers with built-in subwoofers you have from any power strips, surge protectors or power conditioners and plug them directly into the wall or, I presume, into a power regenerator, though I haven't tried the later yet. I did the former and my system felt transformed, the entire frequency range felt more powerful but especially the bass! I had to reduce the subwoofer levels on both my preamp and on the back of my speakers for the bass to be at neighbor friendly levels since I live in a condo. I assume this performance improvement was due to the lowering of power impedence since that's the only thing I changed. Thank you for the advice Paul in helping us improve how our systems sound! Sincerely, Ian in San Diego My system: Goldenear Triton Ones at L, R, SL, SR channels Goldenear Reference Supercenter for center channel 4 Goldenear in-ceiling HTR-7000s at 4 height channels 2 Parasound A51 5-channel power amplifiers Marantz AV8805 Preamp Processor Oppo 203 Blu Ray Player
Impedance wanders all over the road normally when excited with pure tones. Complex wave forms like partial or full octave white or pink, let alone music causes wild averaging of the impedance at any given microsecond. If the amp is solid and stable from 4 to 16 Ohms, nothing will escape you. If you have the raw headroom to do what the program requires, you have it made. You can check your issue with an O-scope to check for flat topping and distortion which is a lack of headroom. 3 more silly dB can smoke your amp. Most mixed music will have a dynamic range of at least 10dB so keep spare fuses handy if you push your luck. In the incredibly rare instance of mismatching drive impedances like Paul goes through, the mismatch would have to be so severe to cause that kind of roll off in the low end that the likelyhood of anyone noticing would be tricky. The capacitor coupled output of anything tube is going to be sort of scarce also since an output transformer is usually involved which negates the circuit described. Failing cathode caps and other coupling interstage caps could more likely hurt you in the low end which is why Paul like the film caps or Mylars.
Interesting stuff. General concept of a voltage divider (wanting the biggest voltage drop across the input of the amp.) Also, good topic with tube preamps. Microphone direct boxes share this general subject of ratios of impedance between input and output. Lots of direct boxes use small audio transformers for this purpose, I believe. Of course microphone output voltage is tiny, and the transformers are very small. Because of the inductances involved, direct boxes, with transformers, can color the sound of a mic (similarly to the capacitor in the tube output circuit, that Paul was describing, except the inductors pass low frequencies easier than high ones.)
The pure resistive voltage divider does not explain loss of bass. All frequencies are equally attenuated, its like a volume control. You are correct though the pre-amp output or any other capacitor in the signal path, can affect the ratio of lower to higher frequencies. Phase shift in the lower frequencies can also have an affect on how the bass sounds even if the level is not much attenuated with relation to higher frequencies. A lot of times the rule of thumb does not guarentee better bass. If anything high output impedance will more likely affect treble as the cable to and input capacitance of the power amp creates a reactive load causing disturbances. Lower pre amp output impedance will dampen these disturbances better but can only do so effectively close to the pre-amp output connection. This is the similar effect we see with speaker cables. I try to use a DC coupled signal path from DAC right through to the speaker terminals. There are also claims of increased dynamics with higher power amp input to pre amp output impedance. It depends a lot on the power amp input stage topology and type of input divices used. There are even some high end power amps which have a 20k resistor in series with the input of the power amp which drives a summing node similar to an inverting op amp circuit. There are no issues with bass performance. I think we are into the territory where simple circuit analysis does not give all the answers.
By the way I use one of your earlier model preamps driving a Nakamichi PA7 amp and a pair of Infinity RS 2.5 speakers and I've tried many preamps( all of which are sitting in the closet including my Conrad Johnson preamp) The PS Audio preamp does the job with perfection.
Paul: before I start the video today we're in a new room, here's a little backstory about this awesome product. Anyways here's today's question. Old fashioned genuine storytelling and sales, where's the "smash that like/subscribe" stuff flying at you 100mp/h? This dude doesn't even have one cut and I'm glued. So awesome.
Known as cutoff frequency, where fc = 1/(2piRC) where C is the value in Farads of the coupling capacitor (aka:DC blocking capacitor) and R is the impedance of the amplifier input in Ohms. As you can see, the larger R*C is, the lower the cutoff frequency will be.
मुझे यह तो ठीक से पता नहीं कि आप कौन हैं , लेकिन इतना समझ रहा हूँ कि आप अपने विषय के बहुत अच्छे जानकार होने के साथ ही एक बहुत शानदाार कान भी रखते हैं । कृपया सबको बताएँ कि ध्वनि तरंगों की गति , माध्यम , माघ्यम की स्थिति ( सभी प्रकार से ) किस ढंग से उपयोग किया जाए कि एक अच्छा एम्प्लिफायर लगभग ठीक से स्पीकर सेट पर काम कर सके ।
Greetings from Argentina 🙋♂️ Hello Paul, I've been following you for about a year and I really like your quality in explanations and your cordiality. Thanks for sharing your knowledge with audiophiles 👏👏👏👏👏👏👏 Speaking of preamps, I've read that if you have a tube amp with very good gain, you can use a passive preamp, well done of course, as it will be the most transmission. pure without modifying or coloring the music. I would like to know your opinion about it. Thank you very much in advance and best regards.
A small tripod can turn your phone into a document camera. You ca just record the work you do on the notepad, so you don’t have to give that up, and then add it to the side of the frame later.
There are small whiteboards you can set on the desk and write on. A standard whiteboard marker would be easier to see. I also think a whiteboard on the wall can still be informal, it's just how you approach it. You might like writing on a fixed surface. And others will use it in the room too. Thanks for your videos, Paul. Very helpful.
On my pre-amp analysyzis only usable caps were 10uF-100uF. We are gettin into matters of caps used in each amp stage. If I used pre-amp circuit of 1uF cabs, the output would be fine in a scope or pc analyzis. But if I add amplifier the output change and base roll.of happens. This why I used 100uF caps in my preamp and amp to prevent that.
Is there a tutorial series/sites for home/custom-building audio equipment? Not for money-saving (obviously you'll be losing more); but for learning, customizing, and enjoying the experience and such? May be a help to pre-engineering (without the full commitment).
Thanks Paul. So am I right in extrapolating that a low powered amp will work well with a low powered pre amp? I ask because I have the RME ADI 2 DAC and apparently makes a good pre amp. I will soon be buying a single ended valve amp to try different valves out. I have no reason to asume this won't work but I would be grateful if you could reassure me or correct me? PS my speakers are 6 ohm; my amp gives me the choice of 4 or 8 ohms so I have it set at 4 ohm out.
Impedance is measured in ohms but it is not a resistor . it is the resistance to pass a AC current though an inductor that is measured in henries. "not though a resistor" inductance is Z sub L so it is Z sub L= Jx with uses Ohms in the final expression. You can not use a ohmeter to measure impedance period. there are instruments to read impedance directly.
The moment you picked up that paper...LIKE WATCHING LIGHTNING STRIKE!! Love your videos Paul but you tend to get way off topic. Thankyou for getting DOWN TO BUSSINESS!!!
Correct me if I am wrong, but isn't a lack of power the typical cause of 'bass rolloff' when using a low impedance load? Let me explain, when the impedance is too low, the demand for current obviously increases to maintain the voltage on the output. However, if the circuitry providing the power can't keep up, it won't be able to deliver the voltage requested. This is normally compensated for by capacitors with reserve power to deliver extra power dynamically when needed, however, with low frequency signals, the caps don't have time to recharge, so the volume will drop on low frequencies.
If it is tube amp, then it as this video explains, it is they have a capacitor that acts as a filter limiting base output so power available is immaterial.
"dampening factor" is inverse to "output impedance" ... that's why the power amps have 0.1Ω or 0.01Ω output impedance driving speakers that (usually) have input impedances of 4+ Ω. Please keep in mind that a loudspeaker is not a purely ohmic resistor (impedance), but a complex system with a frequency-depended impedance.
nice explanation... I am still confused with the signal reduction. I cannot understand why this happens. When you refer to signal what do you mean, current, voltage, both?
My tube preamp has a cathode follower output which feeds my long interconnects just fine. Not sure how low the output impedance is but there is no high or low frequency roll off but there is when I use my Dynaco Pas 3 which has no cathode follower.
That's exactly the reason that cathode followers are used, low output impedance. In guitar amp circuits they're mainly used to drive tone stacks for the same reasons here, it's driving a higher impedance device, lower source loss.
Hello I have an audio issue that I can't get rid of. It's a light humming and hissing sound coming from my speakers. I tried one of the ifi ground loop device directly behind my amplifier and it lowered it alittle, but it's not completely gone. I have an RCA ground loop isolator to the input of the amplifier and that also helped, but still have humming and hissing. I have XLR-RCA cables as well as well shielded speaker wires running to speakers and all my devices are on the same outlet. The amplifier was replaced as well. Can anyone tell me what else I could do to completely eliminate the hissing and humming sounds? Thanks.
Your sympathy is infectious Paul but as a teacher, you need someone who help you improve your technical skills, I know very little about it but after your explanation I'm more confused ☺
Hi Paul. I follow your youtube videos regularly. I looked at these old ones a bit too, and I found one question that I would ask in one of them, more precisely, in this one. So I have a SONY TA N90ES power amplifier and a SONY TA E80ES preamplifier. The amplifier specifications read as follows: INPUT SENSITIVITY (TAN-80ES) Unbalanced: 1 V, 30 kohms Balanced: 0.5 V, 600 ohms and, the preamplifier specifications read as follows: OUTPUT SENSIVITY (TAE-80ES) Unbalanced: 1.5V, 700 ohms Balanced: 3V, 1.2kohms How to combine to get the best result? Balanced or unbalanced? Thank you.
Better late than never ... : Unless you are using 50m of cable between the 2 amps, the XLR ("balanced") cable won't be making much difference. Way bigger influence will the electronic circuitry have that converts the signal for either out- / in-put. So unless you have the schematics and can look up with signal path is the "native" one (that with the least components in it), there's only 2 way to find out: listening to some music, or reading up some reviews.
We rode our bikes In to Toronto looking for used queen and Led Zeplin albums. If we found a European pressing we thought we were in heaven. But they had to be between $2 and $7. That is all we could afford. It was 1980 and we were in grade 9
Do not forget to lock up the Bass, and make sure it is not vibrating the furniture like a big car stereo sub? Pressure comes from Gravity not sound vibration. My mint 63 RCA Stereophonic with tube tuner and amp with AFC will kick your. Tesla worked for RCA, at one time, because he invented most of it anyway. Mine Retailed for $185.00 . Don't think I am going to trade it in.
Hello sir, thank u for this video. I have kind of the same question I think . I've got set of active speaker which are 30k ohm each and want to connect it to my audio interface but don't wanna loose quality of sound, so I would like to buy a set of cable which most of them come in 24 awg, but I'm thinking in 14 Awg or 16 Awg. Can you help to matching the impedance?
I guess I am too late, but let me give some short answer nevertheless: if those are ACTIVE speakers, they basically are power amps and loudspeaker in one. So you need only a standard RCA cable to connect the preamp to the power amp, as there is NO MATCHING of impedances - that exactly what Paul talked about. AWG24 is 0.2mm², which is enough to drive that 30.000Ω input impedance of your speakers - the current flowing through that cable is minimal (milliamperes). If you want to get fancy, get some AWG23 cables with good connectors. musiccritic.com/equipment/cables/rca-cables/#Useful-Item-Guide You need AWG16 (1.3mm²), AWG14(2mm²) or (IMHO better) AWG11(4mm²) cable for PASSIVE loudspeakers because the power amps puts several amperes of current through them, driving an impedance of nominally 4Ω or 8Ω (and at some frequencies it might go down to 2 or less, depending on the speaker). That's 10.000 times more than what you preamp has to do.
@@memyshelfandeye318 Ok I get it. So, will I get the full range of spectrum of my speakers capacity, without loosing information in the low end with 24 AWG?
The bass from my TT is just an unmusical murmur. And it's not my speakers, they sound great on the same music in CD. Maybe a preamp will solve this issue?
Ok. Sounds possibly like you have no phono pre-amp, which is not so much as a pre-amp (although it does increase the signal level significantly), but it's main purpose is to correct the frequency curve that is done in the cutting process of a vinyl record. You need to either have your turntable connected to the phono input on your amp or some turntables have a built in phono pre-amp and they deliver normal line level output like your CD player does. They are for where your amp does not have a dedicated phono input. Lastly, you can buy a separate phono pre-amp.
I’m a pretty firm believer in not mixing pre-amp and amp brands. Stick with the same manufacturer. This way you know both were paired to get the best sound output.
Amps are not "paired". You always want to drive a high-impedance input with a low-impedance output. Unless you get into radio frequency range, there you want paired, constant impedance (e.g. 50 Ohms) to avoid signal reflections, but those effects are of no concern in the audio band. Audio signals are not magical, they are electrical signals (AC, unless you have some DC overlayed, but you dont want that) ranging from 20Hz to 20,000Hz (or 15-25k, there is no rule of nature about that. Ask bats ;-) ) and they follow the same physical rules as any other low-frequency AC signal. Those signals do not know about Brand tags on the front, only about the physical properties of the electronics. And no, brands generally do not really "pair" their electronics. No matter what the marketing department says.
@@memyshelfandeye318 putting all technical matters aside the point you miss is that hours upon hours of listening and testing happened for that same manufactured pre-amp and amp. How was it tested? Together. You’re crazy to think otherwise. You yourself should know that each manufacturer builds their components with a certain sound in mind. They certainly are not built equally and some purposely roll off high frequency, etc. Each are shielded differently too. Again by mixing and matching you take a risk of having distortion introduced and high volume and low volume issues as well as overall not sounding good. The people I see who have a different pre-amp and amps are those with money to burn. It’s a never ending cycle of changing out equipment. I’ve had both my systems for 25 years. Same pre-amp and amp manufacturer, respectively. I realized too that I prefer to spend money on cars and just be satisfied with my home audio equipment. I don’t make enough to satisfy both cravings like some folks do.
Yes. Also realize the higher the impedance, the easier it will be susceptible to noise pickup. So the 22k ohms to 47k ohms input impedance you usually see on an amplifiers input, is a compromise-high enough input impedance to drive easily, but low enough that it doesn’t pick up too much noise.
Well done again Paul.. I was wondering I have a Rogue Audio tube amp & Turntable& Cd player, do u think that I should add a piece of audio equipment to augment the sound (make it better)
A CD player MUST have a DAC of some sort to work, without it, it can't just send a digital signal into a preamp, unless it has a way of converting the digital signal to analog built in. In the case of the Naim CD5i-2, it has a built in DAC, and it's improved over the MKI version from what I read. You don't say which Rogue Audio amp you have, is it an integrated, amp or what? You will need a preamp to control the inputs from TT, CD player etc to the amp, and it generally will have a volume control and perhaps tone controls and a balance knob at the very least. An integrated is just that, a preamp and amp built into one single chassis. Separates are just that 2 separate boxes, one for the preamp, and one for the amp, and this is what Paul is talking about and getting them to match. So if you have say, solid state preamp, it may, or may not be matching up well with the tube amp and I have heard if you go solid state with tubes, best to have the amp be tube, the preamp SS because it's often easier to match them up that way and the reverse unless the tube pre has a buffer stage for the output impedance. Hope this helps.
Speaking of DAC's I heard some people say the old TDA 1540's sound better than a lot of new D/A converters so I'm not in a rush to replace my old 14 bit CD player that uses a 1540.
In this case, connecting your CD player directly to the input of the Cronus will do fine as it's analog to analog. If the Chronus has a digital input section and your CD player needs an external DAC then you would use the digital connection, be it optical or Tosslink most likely to connect the CDP to the integrated. In this case, you have a tube integrated. Might be time to check the state of the tubes, especially the output tubes and see if they still meet specs as they can degrade over time, usually in less time than a typical SS transistor will (it does too, but takes at least 20 years before you notice any degradation) would be my guess, also tube rolling might be in order if all tubes sound fine, going from say some Russian tubes to Tung Sol tubes of the appropriate type for your amp may help things as various brands and types of tubes (compatible types that is) will have differing voicing to each other, which is not as readily apparent with SS transistors.
Is it a picture on video from Kenrick Sound channel? If so, have you listen them in person and what is this experience was like? (You got so friendly and nice channel on RUclips ;)
Hi Paul .... Me again.... You answered this very often asked question very well... but I do question your choice of using mosfets after the tube phono pre amps .. I would prefer to see a cathode follower driver maybe... they would provide the lower impedance ... Have you ever thought of tri amping those IRS 5's they might sound much much better .. What are your views on LF driver voice coil diameters ? The 12" drivers in those IRS columns look a bit wimpy to me .. steel baskets... small magnets ( I'd love to see the Theile/ Small data for them ) they only appear to have 2" VC's... I much prefer 4" coils because of the improved Bl and consequent lower Qte and higher force factor... You can contact me on Facebook if you like.. I have Hons Degrees in electrical and electronic engineering and a past member of the Sydney SAE... loudspeaker engineering and acoustics is my passion right now ...
Interesting, I had an idea a few years ago to use tubes in the driver circuit for a power amp, as to boost the voltage before the transistors or fets boost the current. 2" vc is pretty standard for a 12", only recently have large voice coil diameters started becoming a thing. From what I can tell one benefit to smaller coils is a tighter coil gap, which may lead to better linearity or something. Maybe just manufacturing tech of the time, but surely someone would've experimented with vc diameter/winding counts.
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He's a master at conveying engineering information to an audience of non-engineers. Not an easy task.
Yeah Paul is the right man for doing what hes doing thats for sure
Yes, it's a tough job to do that effectively, without using math. Using ohm's law and the simple equations for power would make it easier to see the relationships, and the resulting explanations. Paul's got his work cut out for himself in not using math to explain things.
@@bal20 was just thinking this. Well said 👍
If you don't want to lose bass don't lend it to anybody. I lent my G&L to a guy back in the 90's. He left town in the "middle of the night" and I never saw my bass again. I had lost all of my bass.
Thanks for the video Paul.
Leo is not impressed.
Paul's love of teaching really shines through on this one. :)
Thank you, Paul. I wish you did explain those technical matters with a whiteboard. I can't see well in your note. We love to hear your technical class more to understand the science of audio to try to recreate music aculeate in the studio.
Love the technicality of this video. When you get deep into the subject :o I'm hooked
Thank you Paul for posting this video. Great work explaining such concepts to non techy folks !
Please keep up the good work !
SBF
Ramble all you want Paul. I really enjoyed your explanation. My father and I really enjoy watching your videos. Thank you!
It comes down to enjoy the music but it's nice to understand how it works. Thanks for the info
Loved the intro music; loved the casual instructional presentation. Very glad to have happened upon your quality channel. Subscribed.
You make a very good teacher, thanks.
He's not writing the book on it, he's just explaining the general idea.
I like to describe it using a teeter totter analogy where the left side of the teeter totter represents a preamp and the right side represents an amplifier and the distance from either end to the pivot represents impedance.
When the pivot is centered between the two ends of the teeter totter, the distances from either end to the pivot are equal. The impedances are equal and both ends of the teeter totter move up and down the same distance, a ratio of 1:1.
As you move the pivot from the center towards the preamp side, the distance between the pivot and the preamp become shorter (impedance decreases), while the distance from the pivot to the amp side becomes longer, (impedance increases).
At the same time the distance that the preamp end moves up and down decreases compared to the distance that the amp side moves up and down which increases.
The ratio can increase from 1:1, 1:10, 1:100 to the limits of the amp where it starts to distort.
The times where matching of input impedance to output impedance for line signals is long gone for most equipment. The output impedance is about 10e2 ohms while the input impedance is about 30kohm-50kohm range. In the days of old telephone centrals the input and output impedance was matched to 600 ohm. The matching of impedances is much more crucial when matching microphone impedance to microphone preamp.
Hi Paul.
Tricky question to answer with voltage divider theory. I understand you want to keep it simple but there are other factors here other than the fact that the signal is being attenuated.
I doubt a power amp will create back EMF to a pre-amp like a speaker will present to the output of a power amp.
A Power amp dont have a reactive (non linear) input load especially at low frequencies. As the power amp input stage is biased into class A it will not (or should not at least if a good design) have a significant dependance on source impedance, especially some characteristic that creates additional voltage drops at bass frequencies only.
Often a resistor is placed in series with the input of a power amp to limit HF bandwidth. This does not ruin the bass performance.
Most power amps will even sound acceptable with a 10k passive volume pot and that is how integrated amps are often made.
One issue with high pre amp output impedance is the interaction with long cable leads, also including input capacitance if a power amp. With short interconnects 1000 Ohms should not be an issue. With very long interconnects a lower output inpedance like 200R is better.
It is most likely that a pre amp with lower output impedance is better designed and will stay in class A for all typical cable and power amp input impedance. This gives a more transparent natural sound.
Thanks so much for the detailed explanation. I recently bought a Schiit Saga S (o/p impedance 180 ohms) feeding into a Crown XLS 1002 (i/p impedance not specified but allegedly 🙂10K SE) and was feeling a loss of bass - maybe time to change the amplifier too
How to avoid losing bass?
Unplug any power amplifiers, subwoofers or speakers with built-in subwoofers you have from any power strips, surge protectors or power conditioners and plug them directly into the wall or, I presume, into a power regenerator, though I haven't tried the later yet. I did the former and my system felt transformed, the entire frequency range felt more powerful but especially the bass! I had to reduce the subwoofer levels on both my preamp and on the back of my speakers for the bass to be at neighbor friendly levels since I live in a condo. I assume this performance improvement was due to the lowering of power impedence since that's the only thing I changed.
Thank you for the advice Paul in helping us improve how our systems sound!
Sincerely,
Ian in San Diego
My system:
Goldenear Triton Ones at L, R, SL, SR channels
Goldenear Reference Supercenter for center channel
4 Goldenear in-ceiling HTR-7000s at 4 height channels
2 Parasound A51 5-channel power amplifiers
Marantz AV8805 Preamp Processor
Oppo 203 Blu Ray Player
Wow thanks, I'll try that. Cool.
I should thank you Paul for these videos as they bring me back to the days when I worked in audio and I miss them a lot.
Impedance wanders all over the road normally when excited with pure tones. Complex wave forms like partial or full octave white or pink, let alone music causes wild averaging of the impedance at any given microsecond. If the amp is solid and stable from 4 to 16 Ohms, nothing will escape you. If you have the raw headroom to do what the program requires, you have it made. You can check your issue with an O-scope to check for flat topping and distortion which is a lack of headroom. 3 more silly dB can smoke your amp. Most mixed music will have a dynamic range of at least 10dB so keep spare fuses handy if you push your luck. In the incredibly rare instance of mismatching drive impedances like Paul goes through, the mismatch would have to be so severe to cause that kind of roll off in the low end that the likelyhood of anyone noticing would be tricky. The capacitor coupled output of anything tube is going to be sort of scarce also since an output transformer is usually involved which negates the circuit described. Failing cathode caps and other coupling interstage caps could more likely hurt you in the low end which is why Paul like the film caps or Mylars.
Paul, pencil and paper don't cut it in youtube videos, please use a whiteboard instead. Love your videos!!
Interesting stuff. General concept of a voltage divider (wanting the biggest voltage drop across the input of the amp.) Also, good topic with tube preamps. Microphone direct boxes share this general subject of ratios of impedance between input and output. Lots of direct boxes use small audio transformers for this purpose, I believe. Of course microphone output voltage is tiny, and the transformers are very small. Because of the inductances involved, direct boxes, with transformers, can color the sound of a mic (similarly to the capacitor in the tube output circuit, that Paul was describing, except the inductors pass low frequencies easier than high ones.)
The pure resistive voltage divider does not explain loss of bass. All frequencies are equally attenuated, its like a volume control.
You are correct though the pre-amp output or any other capacitor in the signal path, can affect the ratio of lower to higher frequencies. Phase shift in the lower frequencies can also have an affect on how the bass sounds even if the level is not much attenuated with relation to higher frequencies.
A lot of times the rule of thumb does not guarentee better bass. If anything high output impedance will more likely affect treble as the cable to and input capacitance of the power amp creates a reactive load causing disturbances. Lower pre amp output impedance will dampen these disturbances better but can only do so effectively close to the pre-amp output connection. This is the similar effect we see with speaker cables.
I try to use a DC coupled signal path from DAC right through to the speaker terminals. There are also claims of increased dynamics with higher power amp input to pre amp output impedance. It depends a lot on the power amp input stage topology and type of input divices used.
There are even some high end power amps which have a 20k resistor in series with the input of the power amp which drives a summing node similar to an inverting op amp circuit. There are no issues with bass performance.
I think we are into the territory where simple circuit analysis does not give all the answers.
Interesting point
Good job Paul. When I try to explain this to people they usually fall asleep,lol.
By the way I use one of your earlier model preamps driving a Nakamichi PA7 amp and a pair of Infinity RS 2.5 speakers and I've tried many preamps( all of which are sitting in the closet including my Conrad Johnson preamp) The PS Audio preamp does the job with perfection.
Paul: before I start the video today we're in a new room, here's a little backstory about this awesome product. Anyways here's today's question. Old fashioned genuine storytelling and sales, where's the "smash that like/subscribe" stuff flying at you 100mp/h? This dude doesn't even have one cut and I'm glued. So awesome.
ƒc = 1/(2πRC) - Formula for frequency cutoff of a high pass filter. The larger the produce of RC, the lower the cutoff frequency.
Even the intro music for this video sounds great!
I still have a pair of Polk 5" 2/way from 1989, still great shape. I should go and look and see model.
Known as cutoff frequency, where fc = 1/(2piRC) where C is the value in Farads of the coupling capacitor (aka:DC blocking capacitor) and R is the impedance of the amplifier input in Ohms. As you can see, the larger R*C is, the lower the cutoff frequency will be.
I would love to have the JBL 4355, powerhouse speakers for sure.
That makes a lot of sense now. Thank you
मुझे यह तो ठीक से पता नहीं कि आप कौन हैं , लेकिन इतना समझ रहा हूँ कि आप अपने विषय के बहुत अच्छे जानकार होने के साथ ही एक बहुत शानदाार कान भी रखते हैं ।
कृपया सबको बताएँ कि ध्वनि तरंगों की गति , माध्यम , माघ्यम की स्थिति ( सभी प्रकार से ) किस ढंग से उपयोग किया जाए कि एक अच्छा एम्प्लिफायर लगभग ठीक से स्पीकर सेट पर काम कर सके ।
Greetings from Argentina 🙋♂️ Hello Paul, I've been following you for about a year and I really like your quality in explanations and your cordiality. Thanks for sharing your knowledge with audiophiles 👏👏👏👏👏👏👏 Speaking of preamps, I've read that if you have a tube amp with very good gain, you can use a passive preamp, well done of course, as it will be the most transmission. pure without modifying or coloring the music. I would like to know your opinion about it. Thank you very much in advance and best regards.
Loving your videos as always!! Thanks for spreading the knowledge Paul :)
In for repair, great product... lmao! Good one Paul.
Everything breaks at some point - great places fix them after the sale
Hi Paul,
Seriously, you need a White Board!
Maybe a small whiteboard with thick markers so we can see the lines :)
A small tripod can turn your phone into a document camera. You ca just record the work you do on the notepad, so you don’t have to give that up, and then add it to the side of the frame later.
There are small whiteboards you can set on the desk and write on. A standard whiteboard marker would be easier to see. I also think a whiteboard on the wall can still be informal, it's just how you approach it. You might like writing on a fixed surface. And others will use it in the room too. Thanks for your videos, Paul. Very helpful.
Chalkboards would be better for the camera
And a plan...
I love watching your videos!!
Love you videos. They're great and educational.
Treble hooks and a solid net are good ways to avoid losing bass.
On my pre-amp analysyzis only usable caps were 10uF-100uF. We are gettin into matters of caps used in each amp stage. If I used pre-amp circuit of 1uF cabs, the output would be fine in a scope or pc analyzis. But if I add amplifier the output change and base roll.of happens. This why I used 100uF caps in my preamp and amp to prevent that.
Thank you for explaining
Can Sprout manufacturing be outsourced to Belgium? I seem to recall hearing rumors of a factory over in Brussels.
Thought this was a video about fishing. Still interesting though! 👍
🤣
Is there a tutorial series/sites for home/custom-building audio equipment? Not for money-saving (obviously you'll be losing more); but for learning, customizing, and enjoying the experience and such? May be a help to pre-engineering (without the full commitment).
I’m glad, I agreed that I don’t have to understand everything I use & love :-) Still, thanks for your great efforts!
"It's in for repair". Shhhhhhhhhh Paul, that's not good for business, haha!
Thanks Paul.
So am I right in extrapolating that a low powered amp will work well with a low powered pre amp?
I ask because I have the RME ADI 2 DAC and apparently makes a good pre amp. I will soon be buying a single ended valve amp to try different valves out.
I have no reason to asume this won't work but I would be grateful if you could reassure me or correct me? PS my speakers are 6 ohm; my amp gives me the choice of 4 or 8 ohms so I have it set at 4 ohm out.
Impedance is measured in ohms but it is not a resistor . it is the resistance to pass a AC current though an inductor that is measured in henries. "not though a resistor" inductance is Z sub L so it is Z sub L= Jx with uses Ohms in the final expression.
You can not use a ohmeter to measure impedance period. there are instruments to read impedance directly.
mtabernig he was make it easy to understand, otherwise some people will get even more confuse!
???????What?????
The moment you picked up that paper...LIKE WATCHING LIGHTNING STRIKE!! Love your videos Paul but you tend to get way off topic. Thankyou for getting DOWN TO BUSSINESS!!!
This is like the Mr. Rogers of audio equipment
Thankfully!
Very informative! Thank you.
I clicked on this thinking it was a bass fishing video lol
Note from below...the power amp is designed for subwoofers.
your most interesting video...watched it 3x so far...still confused
Correct me if I am wrong, but isn't a lack of power the typical cause of 'bass rolloff' when using a low impedance load?
Let me explain, when the impedance is too low, the demand for current obviously increases to maintain the voltage on the output. However, if the circuitry providing the power can't keep up, it won't be able to deliver the voltage requested. This is normally compensated for by capacitors with reserve power to deliver extra power dynamically when needed, however, with low frequency signals, the caps don't have time to recharge, so the volume will drop on low frequencies.
If it is tube amp, then it as this video explains, it is they have a capacitor that acts as a filter limiting base output so power available is immaterial.
I think you are the closest to the correct answer to the issue of impedance-mismacht
Love you Paul!
Great, thank you! understood!
The power amplifier's damping factor - the higher the rating, the more likely the amp will have a good sounding bass output.
"dampening factor" is inverse to "output impedance" ... that's why the power amps have 0.1Ω or 0.01Ω output impedance driving speakers that (usually) have input impedances of 4+ Ω.
Please keep in mind that a loudspeaker is not a purely ohmic resistor (impedance), but a complex system with a frequency-depended impedance.
nice explanation... I am still confused with the signal reduction. I cannot understand why this happens. When you refer to signal what do you mean, current, voltage, both?
Voltage divider principle
brilliant paul! xx
My tube preamp has a cathode follower output which feeds my long interconnects just fine. Not sure how low the output impedance is but there is no high or low frequency roll off but there is when I use my Dynaco Pas 3 which has no cathode follower.
That's exactly the reason that cathode followers are used, low output impedance. In guitar amp circuits they're mainly used to drive tone stacks for the same reasons here, it's driving a higher impedance device, lower source loss.
so we need a parallel transistor dedicated to the woofer
Thank you!!
I have got your audiophile books how do I get the sacd?
some recording just don't have enough bass that's the way it was recorded . don't always blame your hifi
I clicked on this video thinking it was about fishing lmao
Hello I have an audio issue that I can't get rid of. It's a light humming and hissing sound coming from my speakers.
I tried one of the ifi ground loop device directly behind my amplifier and it lowered it alittle, but it's not completely gone.
I have an RCA ground loop isolator to the input of the amplifier and that also helped, but still have humming and hissing.
I have XLR-RCA cables as well as well shielded speaker wires running to speakers and all my devices are on the same outlet.
The amplifier was replaced as well. Can anyone tell me what else I could do to completely eliminate the hissing and humming sounds? Thanks.
Very very interesting your videos🤗🤗
What do you think about the old Joseph Audio Infinite Slope series two speakers?
Great info
Your sympathy is infectious Paul but as a teacher, you need someone who help you improve your technical skills, I know very little about it but after your explanation I'm more confused ☺
the sound quality comes back
Hi Paul.
I follow your youtube videos regularly. I looked at these old ones a bit too, and I found one question that I would ask in one of them, more precisely, in this one.
So I have a SONY TA N90ES power amplifier and a SONY TA E80ES preamplifier.
The amplifier specifications read as follows:
INPUT SENSITIVITY (TAN-80ES)
Unbalanced: 1 V, 30 kohms
Balanced: 0.5 V, 600 ohms
and, the preamplifier specifications read as follows:
OUTPUT SENSIVITY (TAE-80ES)
Unbalanced: 1.5V, 700 ohms
Balanced: 3V, 1.2kohms
How to combine to get the best result? Balanced or unbalanced?
Thank you.
Better late than never ... : Unless you are using 50m of cable between the 2 amps, the XLR ("balanced") cable won't be making much difference. Way bigger influence will the electronic circuitry have that converts the signal for either out- / in-put. So unless you have the schematics and can look up with signal path is the "native" one (that with the least components in it), there's only 2 way to find out: listening to some music, or reading up some reviews.
I wish there was an option to leave off the vinyl top
So a Marantz 8b’s input résistance is it too low? Can someone pick up this bit of info?
good Budget preamp for ICEpower1200a2?
Awesome thank you. :)
Brilliant!
We rode our bikes In to Toronto looking for used queen and Led Zeplin albums. If we found a European pressing we thought we were in heaven. But they had to be between $2 and $7. That is all we could afford. It was 1980 and we were in grade 9
Japanese pressings have always been considered the best. But I used to buy European imports too.
Do not forget to lock up the Bass, and make sure it is not vibrating the furniture like a big car stereo sub?
Pressure comes from Gravity not sound vibration. My mint 63 RCA Stereophonic with tube tuner and amp with AFC will kick your. Tesla worked for RCA, at one time, because he invented most of it anyway.
Mine Retailed for $185.00 . Don't think I am going to trade it in.
I thought this was a fishing tutorial. I always lose bass of my hook. Large mouth especially when they jump.
Guess I'll keep searching
Thanks a lot :)
Triangle is symbol for op-amp.
Awesome!
Paul..Is biwiring dis engage the crossover system of the speaker?
Not if you are doing right.
Bravo!
Hello sir, thank u for this video. I have kind of the same question I think . I've got set of active speaker which are 30k ohm each and want to connect it to my audio interface but don't wanna loose quality of sound, so I would like to buy a set of cable which most of them come in 24 awg, but I'm thinking in 14 Awg or 16 Awg. Can you help to matching the impedance?
I guess I am too late, but let me give some short answer nevertheless: if those are ACTIVE speakers, they basically are power amps and loudspeaker in one. So you need only a standard RCA cable to connect the preamp to the power amp, as there is NO MATCHING of impedances - that exactly what Paul talked about.
AWG24 is 0.2mm², which is enough to drive that 30.000Ω input impedance of your speakers - the current flowing through that cable is minimal (milliamperes). If you want to get fancy, get some AWG23 cables with good connectors. musiccritic.com/equipment/cables/rca-cables/#Useful-Item-Guide
You need AWG16 (1.3mm²), AWG14(2mm²) or (IMHO better) AWG11(4mm²) cable for PASSIVE loudspeakers because the power amps puts several amperes of current through them, driving an impedance of nominally 4Ω or 8Ω (and at some frequencies it might go down to 2 or less, depending on the speaker). That's 10.000 times more than what you preamp has to do.
@@memyshelfandeye318 Ok I get it. So, will I get the full range of spectrum of my speakers capacity, without loosing information in the low end with 24 AWG?
The bass from my TT is just an unmusical murmur. And it's not my speakers, they sound great on the same music in CD. Maybe a preamp will solve this issue?
Ok. Sounds possibly like you have no phono pre-amp, which is not so much as a pre-amp (although it does increase the signal level significantly), but it's main purpose is to correct the frequency curve that is done in the cutting process of a vinyl record. You need to either have your turntable connected to the phono input on your amp or some turntables have a built in phono pre-amp and they deliver normal line level output like your CD player does. They are for where your amp does not have a dedicated phono input.
Lastly, you can buy a separate phono pre-amp.
That was excelent :-D
I’m a pretty firm believer in not mixing pre-amp and amp brands. Stick with the same manufacturer. This way you know both were paired to get the best sound output.
Amps are not "paired". You always want to drive a high-impedance input with a low-impedance output. Unless you get into radio frequency range, there you want paired, constant impedance (e.g. 50 Ohms) to avoid signal reflections, but those effects are of no concern in the audio band. Audio signals are not magical, they are electrical signals (AC, unless you have some DC overlayed, but you dont want that) ranging from 20Hz to 20,000Hz (or 15-25k, there is no rule of nature about that. Ask bats ;-) ) and they follow the same physical rules as any other low-frequency AC signal.
Those signals do not know about Brand tags on the front, only about the physical properties of the electronics. And no, brands generally do not really "pair" their electronics. No matter what the marketing department says.
@@memyshelfandeye318 putting all technical matters aside the point you miss is that hours upon hours of listening and testing happened for that same manufactured pre-amp and amp. How was it tested? Together. You’re crazy to think otherwise.
You yourself should know that each manufacturer builds their components with a certain sound in mind. They certainly are not built equally and some purposely roll off high frequency, etc. Each are shielded differently too.
Again by mixing and matching you take a risk of having distortion introduced and high volume and low volume issues as well as overall not sounding good.
The people I see who have a different pre-amp and amps are those with money to burn. It’s a never ending cycle of changing out equipment.
I’ve had both my systems for 25 years. Same pre-amp and amp manufacturer, respectively.
I realized too that I prefer to spend money on cars and just be satisfied with my home audio equipment. I don’t make enough to satisfy both cravings like some folks do.
Next how do you measure it?
It's $1243,- in Denmark :(
please ramble more. I wouldn't mind for your videos to be 15 minutes long either.
Do subwoofers need a stand alone crossover?
Very interesting
So what you in fact have is a voltage divider between two components?
I would describe it more like a transformer wound 10:1 or 5:1
Yes. It is exactly a voltage divider.
@@timharig Great tanks! :-)
Yes. Also realize the higher the impedance, the easier it will be susceptible to noise pickup. So the 22k ohms to 47k ohms input impedance you usually see on an amplifiers input, is a compromise-high enough input impedance to drive easily, but low enough that it doesn’t pick up too much noise.
@@mmaranta785 Thank you a lot for your great answer! This is interesting and makes a lot of sense!
You gotta use the right hook
If impedance has to be 10x lower than load how do OTL amps work?
Output capacitor ... that the thing Paul talked about, that steals your bass.
www.audiodesignguide.com/otl/otl.html
Well done again Paul.. I was wondering I have a Rogue Audio tube amp & Turntable& Cd player, do u think that I should add a piece of audio equipment to augment the sound (make it better)
I have a Naim CD5i-2. I'm not sure but are DAC's built into CD player's. Cause if not I don't have an external one for the CD player...
A CD player MUST have a DAC of some sort to work, without it, it can't just send a digital signal into a preamp, unless it has a way of converting the digital signal to analog built in. In the case of the Naim CD5i-2, it has a built in DAC, and it's improved over the MKI version from what I read.
You don't say which Rogue Audio amp you have, is it an integrated, amp or what? You will need a preamp to control the inputs from TT, CD player etc to the amp, and it generally will have a volume control and perhaps tone controls and a balance knob at the very least. An integrated is just that, a preamp and amp built into one single chassis. Separates are just that 2 separate boxes, one for the preamp, and one for the amp, and this is what Paul is talking about and getting them to match.
So if you have say, solid state preamp, it may, or may not be matching up well with the tube amp and I have heard if you go solid state with tubes, best to have the amp be tube, the preamp SS because it's often easier to match them up that way and the reverse unless the tube pre has a buffer stage for the output impedance.
Hope this helps.
Speaking of DAC's I heard some people say the old TDA 1540's sound better than a lot of new D/A converters so I'm not in a rush to replace my old 14 bit CD player that uses a 1540.
Yes I have the Rogue Cronus Magnum 2 Integrated Amp
In this case, connecting your CD player directly to the input of the Cronus will do fine as it's analog to analog. If the Chronus has a digital input section and your CD player needs an external DAC then you would use the digital connection, be it optical or Tosslink most likely to connect the CDP to the integrated. In this case, you have a tube integrated. Might be time to check the state of the tubes, especially the output tubes and see if they still meet specs as they can degrade over time, usually in less time than a typical SS transistor will (it does too, but takes at least 20 years before you notice any degradation) would be my guess, also tube rolling might be in order if all tubes sound fine, going from say some Russian tubes to Tung Sol tubes of the appropriate type for your amp may help things as various brands and types of tubes (compatible types that is) will have differing voicing to each other, which is not as readily apparent with SS transistors.
Is it a picture on video from Kenrick Sound channel? If so, have you listen them in person and what is this experience was like? (You got so friendly and nice channel on RUclips ;)
Paul McGowan It is from Kenrick sound RUclips channel. He repair vintage JBL studio monitors and ship them worldwide.
If you have 5k, you're gonna have ... *treble* :)
Hi Paul ....
Me again....
You answered this very often asked question very well... but I do question your choice of using mosfets after the tube phono pre amps .. I would prefer to see a cathode follower driver maybe... they would provide the lower impedance ...
Have you ever thought of tri amping those IRS 5's they might sound much much better ..
What are your views on LF driver voice coil diameters ?
The 12" drivers in those IRS columns look a bit wimpy to me .. steel baskets... small magnets ( I'd love to see the Theile/ Small data for them ) they only appear to have 2" VC's... I much prefer 4" coils because of the improved Bl and consequent lower Qte and higher force factor...
You can contact me on Facebook if you like.. I have Hons Degrees in electrical and electronic engineering and a past member of the Sydney SAE... loudspeaker engineering and acoustics is my passion right now ...
Interesting, I had an idea a few years ago to use tubes in the driver circuit for a power amp, as to boost the voltage before the transistors or fets boost the current. 2" vc is pretty standard for a 12", only recently have large voice coil diameters started becoming a thing. From what I can tell one benefit to smaller coils is a tighter coil gap, which may lead to better linearity or something. Maybe just manufacturing tech of the time, but surely someone would've experimented with vc diameter/winding counts.
Interestingly MOSFETs have pentode-like transfer functions, so you may be right: their inherent high distortion and impedance requires feedback.