When I was working at Analog Devices we built some high end opamps that were 2" sq brics with a few dozen FET's and transistors inside along with resistors and diodes. These were all discrete parts and I remember we used a ferrite bead on the output lead of this little brick to boost the slew rate to 200 v / us. That was hot stuff for 1970.
@Dave Micolichek Wireless World July 1972 had a design for a discrete component op amp for use in audio preamps. It worked well. www.americanradiohistory.com/Archive-Wireless-World/70s/Wireless-World-1972-07.pdf
@Dave Micolichek It was a great joy to me to discover that trove of magazines I used to read so avidly back in the day. Only too happy to share :-) My favourite issue from 1972 was Linsley-Hood's transmission line speakers. Heaven on a stick was when I acquired my first transmission line speakers in 2000.
@Dave Micolichek Try starting at the home page: www.americanradiohistory.com/index.htm I'm pretty certain the site is legal. It's been around for a while now and contains many old publications of interest to those of us who played with electronics a long time ago. It would be a bitter disappointment to me to have contributed to piracy being a victim of such myself. Found on Keith Snook's website: www.keith-snook.info/wireless-world-magazine/Wireless-World-1972/The%20Transmission-line%20loudspeaker%20Enclosure.pdf If you ever get around to building this, the Radford crossover is heaps better than the original design. I came across a version where the transmission line was straight so the cabinets had to be horizontal. I'm not enough of a Golden Ears to detect whether this was an improvement on the folded design, but the latter is a bit of a bugger to build. The KEF B139 was widely considered the best bass driver in its day.
Slew rate, rise time, TIM (transient intermodulation distortion) was a big thing in the late '70s, Sansui and their Diamond Differential circuit, Kenwood/Trio, Harman Kardon were competitors in the slew/TIM wars
It will be interesting to see how PS audio integrates their ribbon tweeter with their cone midwoofer. That's a common combination, but most examples sound like two transducers and a crossover rather than a seamless loudspeaker, especially in small enclosures. That said, even unloaded, their speaker looks pretty nice.
I have some '80s gear that I still love. Many improvements have been made to op-amps since then, and it's tempting to drop in some new silicon. The usual advantages are lower noise and much higher slew rates. The faster circuits come with the hope for better sound and the increased likelihood of high frequency oscillation. Sparkfun sells tiny circuit boards that allow you to put surface mount devices on through-hole boards. The trick is getting the right capacitors in the right places to keep things stable!
Paul, I just came across this video at random, but we met many years ago, and funnily enough there would be no Osten Audio Labs had it not been for you, we have not crossed paths again since so I will use this as an opportunity to say thank you.
Isn't it cool how some of the best things come about through mistakes? {Learn something new everyday} Cheers to mistakes and what we learn through them.
It's called serendipity. Sri Lanka was formerly called Serendip and Hugh Walpole coined the word based on the fairytale "The Three Princes of Serendip".
Wow, great story. Who slew?! Also now appreciate what analog audio emulators are attempting to do with slew rate controls. Thanks, all the best in 2019
Hi Paul pleas show us a completed pare of those speakers beautiful eye candy, and we know they are going to sound sublime I want some it is Christmas after all lol 😜
turn the top sprout speaker upside down so the ribbons match up and you will have the modern stacked Advent configuration that i fell in love with long ago...thanks Paul
Thanks for posting. I’m now in the process of building Astable multivibrator oscillators. I have found that the uA741 op-amp when viewing on my scope looks like the leaning tower of pizza. CA3140 is a little better. But the LT1007 is the winner in slew rate straight vertical lines on my scope. Do you remember these chips?
Slew rate is ever important as Paul rightly explained... I remember the 741 and the LM301... the latter requires a compensation cap added to it to control its open loop gain ... we have come a long way since those little devices came on the market . My preamplifier is designed around NE5534AN devices the 'AN ' suffix denotes very low noise in nano volts per square root of the applied frequency. They have a slew rate of over 70v / us which ain't at all bad .. You must be aware though .. too much high slew rate maintained throughout the amplifier chain can lead to oscillation effects
Wonder how much this can be measured through the speaker impulse plot and the Speaker frequency damping waterfall plot. This stuff should be measurable in the last chain link? Maybe some speakers are too slow and this gets aliased? Did anyone compare these plots with different amps?
Hee Haw? well my beloved step mother is from Taft, not to far from there. Anyway, Thank you SCOTT!! for not putting metal in your woofer cone!! Looks like I finally have an upgrade from my 90's bose 8in 2 ways.
Outlaw country is the only country I'll listen to and it deserves proper imaging as much as a symphonic or prog rock music, although much of the source material is mono so it really exposes a different side of a system.
I grew up with, Hee Haw, Barbra Mandrel, Carol, Sonny n Cher, on and on..I have tolerence, since my dad did the first part of his childhood in Seminary Mississippi. (Br549? juniors auto sales?) Are you talking on the road again?
I'm a SF Bay Area native who grew up on 60s and 70s rock n' roll and 80s synth stuff so that's my preference (just saw both Gary Numan & LIndsey Buckingham recently) but I lived in Austin, Texas for a couple years and outlaw country has some impressive pillars. I saw Willie and got to see Sturgill Simpson open for him. That was a sweet sweet sweet show! I've got great respect for Willie Nelson, Merle Haggard, Waylon Jennings, Ray Wylie Hubbard, Steve Earle, Sturgill Simpson, and a whole lotta those guys but I don't even have marginal tolerance for commercial country as I would much rather listen to King Crimson & Hawkwind. Sturgill is hardcore psychedelic country. Thumbs up!
Howdy. Slew rate is important. Slew rate determines how well the upper bands can ride upon the bass. The larger the slew rate the better upper band fidelity. Only measuring the bandwidth does not say anything about the slew rate. A poor slew rate degrades the clarity and resolution of the upper bands. Regards.
Here's the short and skinny. Power amplifier frequency response is measured at one watt into a 4 or 8 ohm resistor. Solid state amplifiers invariably look ruler flat across the audio passband by this test. But at higher power levels the high end rolls off and while the power bandwidth may show it to be adequate with a steady state signal the amplifier may not respond fast enough to keep up with the waveform exactly. So amplifiers have to be able to deliver power into real world loads that can be reactive and even kick back with reverse EMF. Big well regulated power supplies with a lot of stored energy in capacitors able to muscle it's way controlling any speaker it's hooked up to keeping up with high frequency transient waveforms sound best. Matti Otala of Harman Karon discovered this back in the mid 1970s. He called the failure of the amplifier to keep up "transient intermodulation distortion." Intermodulation distortion is any distortion that doesn't fit into any of the neatly defined forms of distortion.
Fascinated at your knowledge, Sir. I have seen this kick back, when 2 woofers in parallel and free air. Push down on one and the other will have movement. This is why I am committed to one amp channel for each driver all the way to the top. Transient response just has to be slowed down when people hook multiples in series/parallel to get a big amp to push an array.
Hi! Paul! .. I always enjoy your interesting, and informative videos. Thank you for sharing your knowledge, and experiences with us. ... I don't normally bother you with my comments, but I wanted to wish you, and your family, and friends at PS Audio a very Merry Christmas, and a Great, and Happy New Year. ... Mike
I was about to mention the yellow cone B&W resemblance, too. I have some 804s that are pretty nice speakers. I used to have some 601s that I thought were quite nice as well, from a time when they still made them in England.
Paul I'm a huge fan of yours your videos just make me want to spend more money on equipment WHAT A HOBBY? I go way back to things like acoustat ESL magnet plasmas Randell research cables etc. I'm writing to you about cables and something you said about shielded cables that are connected on one end as a qausi-balanced cable I believe you stated not to do this and if so why not ? I do make cables it's a recipe for me and enjoy it please explain or someone reading this join in thanks
Paul, when you do video responses that require you to mention #'s could you use a white board and list bad to good,I'm not an engineer and these numbers don't give.So an example of slew0-100 bad 100-200 good and 200+ best.Thx's.
Uncle Paul is fibbing again. He does like to embellish a bit. Those are some of the worst parts even back in the day. Maybe he can look into it and make a proper correction because there is just no way.
@Larry Niles I would call it fact checking or maybe peer review. I think Paul owes the community a correction because he has to be mistaken regarding his choice of op-amps. With regards to respect or disrespect, people earn it and with each falsehood told or something lacking solid fact based evidence, it should be pointed out given that this is a public forum. Sorry you couldn't see the humor in my comment. As far as growing up, yea I'm about as grown up as I'm gonna get. Oh well.
I an very sorry to correct you the LM709 was as sluggish as the LM741. ( www.ee.nsysu.edu.tw/lab/F6027/LM709%20Operational%20Amplifiers.pdf www.ti.com/lit/ds/symlink/lm741.pdf ) But you are right that the 741 sounds terrible. Probably one reason why so many recordings from the 70th were so bad. It was used by Revox/Studer (probably by other companies too) in recording equipment in the 70th
My car amp from 1980 is "70volt/μs, 50wpc (rms) 20 to 20kz power bandwidth, with no more than 0.005% total harmonic distortion" But then I'm just a Stereo Junky.
@Dave micolichek, yes! it is the ........PA 6100 with its STK-0049 chip in it. I wish I would have bought a bunch of them. For years the car audio people gave it the ugly looking amp award! with its large fins and all. A very simple amp that when electronically crossed would just fly! But then again that's what they were made for because Sanyo was bi-amping in the seventies. I was fortunate to buy up a lot of different Sanyos of this type, about 10 years ago off eBay. New old stock and almost give a ways. I guess Stereo Junky fits fairly well as that's the profile I use currently. Thanks for the interest!
As far as must have records there seemed to be so much that you excluded. Look as one who is DEFINITELY NOT AN AUDIOPHILE OR A BABBY BOOMER, i have a decidedly different view of of hifi and what makes a great album. Have you ever noticed that the boomers demanded in the 80s that all digital stuff sounded great(no skips etc) and not they condemn all modern generations for liking records and indie lofi alternatve music ?
Your story regarding the 709 op amp doesn't pass the "smell test." The 709 is an externally-compensated device which requires compensation capacitors to be added to the circuit, according to the gain desired (and it's SLOWER than a 741 when set up for a unity-gain application). The 741 is internally compensated, so any circuit designed for it will lack any external compensation and the 709 can NOT be used as a drop-in replacement (even though it is possible to go the other way and use a 741 in a circuit designed for a 709). Also, the 709 had some notoriety for its "popcorn" noise issue and would be a commercial disaster in a production phono pre-amp. Your "mistake" was much more serious than you knew. Ever check the output of your 709 circuit with a scope? It was probably exhibiting parasitic oscillations, which you and your associate apparently thought sounded great. :-/
When I was working at Analog Devices we built some high end opamps that were 2" sq brics with a few dozen FET's and transistors inside along with resistors and diodes. These were all discrete parts and I remember we used a ferrite bead on the output lead of this little brick to boost the slew rate to 200 v / us. That was hot stuff for 1970.
@Dave Micolichek Wireless World July 1972 had a design for a discrete component op amp for use in audio preamps. It worked well.
www.americanradiohistory.com/Archive-Wireless-World/70s/Wireless-World-1972-07.pdf
@Dave Micolichek It was a great joy to me to discover that trove of magazines I used to read so avidly back in the day. Only too happy to share :-)
My favourite issue from 1972 was Linsley-Hood's transmission line speakers. Heaven on a stick was when I acquired my first transmission line speakers in 2000.
@Dave Micolichek Try starting at the home page: www.americanradiohistory.com/index.htm
I'm pretty certain the site is legal. It's been around for a while now and contains many old publications of interest to those of us who played with electronics a long time ago. It would be a bitter disappointment to me to have contributed to piracy being a victim of such myself.
Found on Keith Snook's website: www.keith-snook.info/wireless-world-magazine/Wireless-World-1972/The%20Transmission-line%20loudspeaker%20Enclosure.pdf
If you ever get around to building this, the Radford crossover is heaps better than the original design. I came across a version where the transmission line was straight so the cabinets had to be horizontal. I'm not enough of a Golden Ears to detect whether this was an improvement on the folded design, but the latter is a bit of a bugger to build. The KEF B139 was widely considered the best bass driver in its day.
Slew rate, rise time, TIM (transient intermodulation distortion) was a big thing in the late '70s, Sansui and their Diamond Differential circuit, Kenwood/Trio, Harman Kardon were competitors in the slew/TIM wars
What fun it is to ride and sing a slewing song tonight!
It will be interesting to see how PS audio integrates their ribbon tweeter with their cone midwoofer. That's a common combination, but most examples sound like two transducers and a crossover rather than a seamless loudspeaker, especially in small enclosures. That said, even unloaded, their speaker looks pretty nice.
I have some '80s gear that I still love. Many improvements have been made to op-amps since then, and it's tempting to drop in some new silicon. The usual advantages are lower noise and much higher slew rates. The faster circuits come with the hope for better sound and the increased likelihood of high frequency oscillation. Sparkfun sells tiny circuit boards that allow you to put surface mount devices on through-hole boards. The trick is getting the right capacitors in the right places to keep things stable!
Wow, now I understand why some amps sounded sluggish. Thanks Paul!
Paul, I just came across this video at random, but we met many years ago, and funnily enough there would be no Osten Audio Labs had it not been for you, we have not crossed paths again since so I will use this as an opportunity to say thank you.
Isn't it cool how some of the best things come about through mistakes? {Learn something new everyday} Cheers to mistakes and what we learn through them.
It's called serendipity. Sri Lanka was formerly called Serendip and Hugh Walpole coined the word based on the fairytale "The Three Princes of Serendip".
WOW! What a story!
Wow, great story.
Who slew?!
Also now appreciate what analog audio emulators are attempting to do with slew rate controls.
Thanks, all the best in 2019
MIND = BLOWN... What a story...
Hi Paul pleas show us a completed pare of those speakers beautiful eye candy, and we know they are going to sound sublime I want some it is Christmas after all lol 😜
turn the top sprout speaker upside down so the ribbons match up and you will have the modern stacked Advent configuration that i fell in love with long ago...thanks Paul
Thanks for posting. I’m now in the process of building Astable multivibrator oscillators. I have found that the uA741 op-amp when viewing on my scope looks like the leaning tower of pizza. CA3140 is a little better. But the LT1007 is the winner in slew rate straight vertical lines on my scope. Do you remember these chips?
Slew rate is ever important as Paul rightly explained... I remember the 741 and the LM301... the latter requires a compensation cap added to it to control its open loop gain ... we have come a long way since those little devices came on the market . My preamplifier is designed around NE5534AN devices the 'AN ' suffix denotes very low noise in nano volts per square root of the applied frequency. They have a slew rate of over 70v / us which ain't at all bad ..
You must be aware though .. too much high slew rate maintained throughout the amplifier chain can lead to oscillation effects
Ah, older opamp... What do you think about the JRC4556 or JRC4558? Any experience with those?
Wonder how much this can be measured through the speaker impulse plot and the Speaker frequency damping waterfall plot. This stuff should be measurable in the last chain link? Maybe some speakers are too slow and this gets aliased? Did anyone compare these plots with different amps?
If I lived in Bakersfield, I would want a really excellent audio system. It would be essential for properly reproducing the Bakersfield Sound.
Hee Haw? well my beloved step mother is from Taft, not to far from there. Anyway, Thank you SCOTT!! for not putting metal in your woofer cone!! Looks like I finally have an upgrade from my 90's bose 8in 2 ways.
Outlaw country is the only country I'll listen to and it deserves proper imaging as much as a symphonic or prog rock music, although much of the source material is mono so it really exposes a different side of a system.
I grew up with, Hee Haw, Barbra Mandrel, Carol, Sonny n Cher, on and on..I have tolerence, since my dad did the first part of his childhood in Seminary Mississippi. (Br549? juniors auto sales?)
Are you talking on the road again?
I'm a SF Bay Area native who grew up on 60s and 70s rock n' roll and 80s synth stuff so that's my preference (just saw both Gary Numan & LIndsey Buckingham recently) but I lived in Austin, Texas for a couple years and outlaw country has some impressive pillars. I saw Willie and got to see Sturgill Simpson open for him. That was a sweet sweet sweet show! I've got great respect for Willie Nelson, Merle Haggard, Waylon Jennings, Ray Wylie Hubbard, Steve Earle, Sturgill Simpson, and a whole lotta those guys but I don't even have marginal tolerance for commercial country as I would much rather listen to King Crimson & Hawkwind. Sturgill is hardcore psychedelic country. Thumbs up!
Howdy. Slew rate is important.
Slew rate determines how well the upper bands can ride upon the bass. The larger the slew rate the better upper band fidelity. Only measuring the bandwidth does not say anything about the slew rate. A poor slew rate degrades the clarity and resolution of the upper bands.
Regards.
Here's the short and skinny. Power amplifier frequency response is measured at one watt into a 4 or 8 ohm resistor. Solid state amplifiers invariably look ruler flat across the audio passband by this test. But at higher power levels the high end rolls off and while the power bandwidth may show it to be adequate with a steady state signal the amplifier may not respond fast enough to keep up with the waveform exactly. So amplifiers have to be able to deliver power into real world loads that can be reactive and even kick back with reverse EMF. Big well regulated power supplies with a lot of stored energy in capacitors able to muscle it's way controlling any speaker it's hooked up to keeping up with high frequency transient waveforms sound best. Matti Otala of Harman Karon discovered this back in the mid 1970s. He called the failure of the amplifier to keep up "transient intermodulation distortion." Intermodulation distortion is any distortion that doesn't fit into any of the neatly defined forms of distortion.
Fascinated at your knowledge, Sir.
I have seen this kick back, when 2 woofers in parallel and free air. Push down on one and the other will have movement. This is why I am committed to one amp channel for each driver all the way to the top. Transient response just has to be slowed down when people hook multiples in series/parallel to get a big amp to push an array.
Mark Fischer another great reply!
Hi! Paul! .. I always enjoy your interesting, and informative videos. Thank you for sharing your knowledge, and experiences with us. ... I don't normally bother you with my comments, but I wanted to wish you, and your family, and friends at PS Audio a very Merry Christmas, and a Great, and Happy New Year. ... Mike
Same to you and yours. Thanks!
those woofers look pretty close to the ones in my b&w 601 series 1. surprised with that as paul dislikes b&w.
I was about to mention the yellow cone B&W resemblance, too. I have some 804s that are pretty nice speakers. I used to have some 601s that I thought were quite nice as well, from a time when they still made them in England.
Paul dislikes the treble of them, he finds it a bit “gnarly”.
I'm sure it's because b+w cost way to much,they are good though.
My amp has a slew rate of 500. Is that good?
Yea,give us some #'s to judge from.
A simple 12AX7 vacuum tube based preamp / buffer stage has a typical slew rate of 1-million volts per microsecond.
Paul I'm a huge fan of yours your videos just make me want to spend more money on equipment WHAT A HOBBY? I go way back to things like acoustat ESL magnet plasmas Randell research cables etc. I'm writing to you about cables and something you said about shielded cables that are connected on one end as a qausi-balanced cable I believe you stated not to do this and if so why not ? I do make cables it's a recipe for me and enjoy it please explain or someone reading this join in thanks
....and now a commercial word from our sponsors.
Paul, when you do video responses that require you to mention #'s could you use a white board and list bad to good,I'm not an engineer and these numbers don't give.So an example of slew0-100 bad 100-200 good and 200+ best.Thx's.
Mistake or universal inspiration?
I have a better understanding explanation.Slew Rate is the speed from the amplifier .Its how fast can the amplifier distribute the signal.
But please bracing and silicon gaskets. A 10 $ solution that makes huge improvement. De couple and add dampening.
Those speakers are going to look just like little B&Ws with those yellow cones.
Just when B&W have abandoned the yellow cones. Maybe they had some leftovers.
@7:22 We popped in the 747... 🤔🛫
Slew 741: 0.5V/ micro second. Anyway, a horrible opamp. Slew 709 half of that: 0.25V / micro second...
Not just me then that looked up the slew on each of those devices. The 709 is not light years faster at all.
So there was something else going on.
Even the 5534 is not especially fast at only 13 v/microsec.
@@johnc8910 13v/us is not slow. even the best chip amps are not usually that fast.
Uncle Paul is fibbing again. He does like to embellish a bit. Those are some of the worst parts even back in the day. Maybe he can look into it and make a proper correction because there is just no way.
@Larry Niles I would call it fact checking or maybe peer review. I think Paul owes the community a correction because he has to be mistaken regarding his choice of op-amps. With regards to respect or disrespect, people earn it and with each falsehood told or something lacking solid fact based evidence, it should be pointed out given that this is a public forum. Sorry you couldn't see the humor in my comment. As far as growing up, yea I'm about as grown up as I'm gonna get. Oh well.
I an very sorry to correct you the LM709 was as sluggish as the LM741. ( www.ee.nsysu.edu.tw/lab/F6027/LM709%20Operational%20Amplifiers.pdf www.ti.com/lit/ds/symlink/lm741.pdf ) But you are right that the 741 sounds terrible. Probably one reason why so many recordings from the 70th were so bad. It was used by Revox/Studer (probably by other companies too) in recording equipment in the 70th
My car amp from 1980 is "70volt/μs, 50wpc (rms) 20 to 20kz power bandwidth, with no more than 0.005% total harmonic distortion"
But then I'm just a Stereo Junky.
@Dave micolichek, yes! it is the ........PA 6100 with its STK-0049 chip in it. I wish I would have bought a bunch of them.
For years the car audio people gave it the ugly looking amp award! with its large fins and all.
A very simple amp that when electronically crossed would just fly!
But then again that's what they were made for because Sanyo was bi-amping in the seventies. I was fortunate to buy up a lot of different Sanyos of this type, about 10 years ago off eBay. New old stock and almost give a ways. I guess Stereo Junky fits fairly well as that's the profile I use currently. Thanks for the interest!
@Dave Micolichek pa6100
This particular video slew me.
As far as must have records there seemed to be so much that you excluded. Look as one who is DEFINITELY NOT AN AUDIOPHILE OR A BABBY BOOMER, i have a decidedly different view of of hifi and what makes a great album. Have you ever noticed that the boomers demanded in the 80s that all digital stuff sounded great(no skips etc) and not they condemn all modern generations for liking records and indie lofi alternatve music ?
Your story regarding the 709 op amp doesn't pass the "smell test." The 709 is an externally-compensated device which requires compensation capacitors to be added to the circuit, according to the gain desired (and it's SLOWER than a 741 when set up for a unity-gain application). The 741 is internally compensated, so any circuit designed for it will lack any external compensation and the 709 can NOT be used as a drop-in replacement (even though it is possible to go the other way and use a 741 in a circuit designed for a 709). Also, the 709 had some notoriety for its "popcorn" noise issue and would be a commercial disaster in a production phono pre-amp. Your "mistake" was much more serious than you knew. Ever check the output of your 709 circuit with a scope? It was probably exhibiting parasitic oscillations, which you and your associate apparently thought sounded great. :-/