My brother had two sets of these. Carver pulls the power out of the wall outlet rather than using big storage caps and big transformer. When you turn these up the lights will flicker badly with the draw of the amp unless you have a strong circuit. They really are loud. He also had a TFM-75 and that amp was two 750 watt mono blocks in one chassis, it was a bruit of an amp and those were very rare.
I seem to recall a review back in the day of Carver's "amazing" magnetic amplifier (the one that had a form factor of an 8" cube) and when they hit a particularly high output, the circuit breaker for the listening room tripped.
Well done! It was a long video but it showed clearly how this circuit works. thank you. When the FTC put out their power ruling that required amplifiers be preconditioned by putting out 1/3 the rated power output for 1 hour before testing was started (circa 1975) the standard class AB amplifier was producing near maximum heat. They cooled down a little when run at full power after the preconditioning. Big amplifiers like the Phase Linear 700 would go into thermal shutdown several times accumulating 1 hour of run time. Then class G and H amplifiers started showing up. By selecting the lower voltage amplifier rails carefully they could run the 1/3 power preconditioning with the amplifier running at full power on the lower voltage rail, the higher voltage rails and transistors only ran during the full power test. This meant less heat sink and smaller power supplies. It was passed off as allowing more dynamic power (true) but the real reason was to get past the preconditioning requirement. Carver improved on that by regulating the input to the power transformer with the triac as you have pointed out, and using additional rail voltages to produce a smaller more powerful amplifier for its physical size. also Thank you for the lesson on differential inputs.
I owned a pair of Silver 7ts back in the 90s. I used them to run a pair of Martin Logan Sequel IIs, driven by a Cary CAD5500 preamp. It sounded great and the amplifiers were so, so powerful - they froze up the woofers on my MLs at one point, and would regularly trip the circuit breaker in the house when going full tilt. I loved them. At least until a friend brought over a Conrad-Johnson MF200 which, while rated for way less power, did things in the bass that the Carvers just couldn't. They sounded weak by comparison (the 9ts would certainly have had a different sound). So I wound up trading them in for a CJ amp. You are misinformed about the origin of the name, though. Bob Carver was a well-respected engineer at Phase Linear in the 70s and 80s, and in the mid-80s made a controversial statement that he had determined a way to measure the transfer function of any amplifier (this being a mathematical function that described the relationship between input and output of an amplifier, i.e., a function that describes the sound of an amplifier) and further that he knew how to modify an amplifier's transfer function so that he could make any amplifier sound like any other, including extremely high-end amps. The tweaky audio press at the time thought he was crazy as I recall, but he got a couple of magazines to accept a challenge and it was generally agreed that he managed to duplicate the sound of both a high-end Mark Levinson and Conrad Johnson amplifier with one of his relatively cheap amps, which would have been the predecesor to these Silver 9ts. The original modified amp went on the market and sold as the M1.5t, which stood for Magnetic Field Amplifier, 1.5kw, transfer function modified - thus the "t" in the model number. He did a couple of other amps including an inexpensive M400t, and then created a statement tube amplifier as a way to set the ultimate target for his "transfer modifying" technology. This was the Silver Seven, and the audiophile press of the day collectively shat itself over the amplifier. Few were sold, as it was really made to give him something to copy, and so he produced the Silver 7t, which was a (relatively) inexpensive, solid-state amp that was supposed to sound exactly like the Silver Seven. As I recall it sold fairly well, but had relatively low current capability, which explains the Silver 9t with its higher damping factor and more sophisticated power supply. I don't know if he ever revealed what the secret was to modifying the transfer function but I have to wonder if those tacked-on resistors, capacitors, and transistors on the amp board don't have something to do with it - maybe it was a modification they made on an individual basis to each amp that left the factory?
+ Alan Westenbrook - Your account agrees with my addled memory. Bob Carver is part genius and part huckster, but nobody could deny his creations worked, if in alarming ways.
I've owned my Silver 9t's for over 30 years! Still working flawless and driving my Legacy Focus Speakers, I hang out at local hifi store a lot. They're flagship amps are Classe. Still wouldn't trade even up! Best amps still.
I still own a pair of these. I bought them used in the late 80's. I had them hooked up to a pair of magnapan tympani speakers, they sounded great for a while. Then something went wrong and the tweeter panel on the left speaker caught on fire so I boxed them up and haven't used them since. I would like to use them again.
Very interesting. Thanks for posting. I have a pair I use in my home theatre to drive subwoofers. An interesting sidenote. At the time these came out I had another power amplifier that put out almost the same power. I'm old ha ha, any way my speakers were a very tough load 4 ohms dropping to two and the only amp I found at the time was a sound craftsman. It was called a class "H" House lights kept time with the music!
What's interesting is that I have a Carver M-4.0T amp, which uses basically the same circuit, but with half the number of output transistors per circuit board. Because of the odd way the second row of transistors is installed here, not to mention other components, it almost seems to me like the 9T took the circuit board (which appears to be the exact same PCB) from one of their stereo amps and "adapted" it as a mono amp. This would explain why you have components tacked on both sides of the board. On mine, quite a few of the smaller PCB-mounted electrolytic capacitors were showing definite signs of age.
Thanks again, as always very interesting I think this kind of amps can be called class g, works with varying voltages per demand. Using the triac ( which can be switched no more than 120 times a second) to stabilize the voltage looks like an early version of SMPS which would probably be used today
If you connect these silver 9s to a standard 15 amp residential power line be prepared to trip the 15 amp breaker regularly due to Bob not using high capicity Caps in the design to be called on to supply up to 10x wattage for transient peaks ,I had to install dual dedicated 20 amp lines to supply the power from the wall to these ,the Carver monoblocks require more power from the wall than my McIntosh Mc-1201 1,200 8ohm watt monoblocks,or my Krell FPB 750s that push over 800 class A watts per channel .
"I dunno whether to like it or not. I *respect* it, though." I remember having precisely the same feeling. It was after a long day of backpacking, and finally we made it to our campsite, where we encountered a big ol' rattlesnake. He loudly announced his presence, coiled up a couple feet high, smack in the middle of the firepit, in *our* campsite. Well... it was *supposed* to be our campsite; suddenly it wasn't.
I used to work with a couple of engineers who had mains leads for there scopes with the earth taken out, this was marked on the plug ! I guess thats one way ? this amp better sound fantastic, I found the automatic gearbox analogy useful...cheers!
that high voltage end of the power supply where the triac is, that reminds of a PWM power supply, the same power supply used in computers, but with a much slower speed than the computers power supply
It's Class G amplifier, used mostly on pro amplifier. Yamaha also used this design on hifi amplifier the Yamaha AST-A10 so what they called Active Servo Amplifier.
My guess by the design of the power supply and the amplifier section layouts are that Bob Carver was trying to make an 'On Demand" Amplifier rather than a "constant on" Amplifier/Heater for cooler running theory.
Interesting design. I can see how it would be more efficient. I also wonder if it would have a better dampening factor (low output impedance) before the negative feedback. My thought being the higher the "resistance" the output transistors have between the speaker and the power rail, the higher it's natural output impedance. So, with a high voltage power rail and low output levels, the uncorrected output impedance would be rather high. But with lower voltage power rails, then the transistor opens up more for the same output power - and you have a lower output impedance.
I remember some of Bob Carver's early designs in the 1980s. They were all solid state and the low height of the case would not allow for a large transformer. They must have used switching power supplies. The audiophile reviewers disliked them. Carver's comeback was "Give me the transfer function of your favorite tube amp and I'll replicate it on my amp." I don't think he succeeded the first time, but he did get closer. I was interested since I had just learned what a transfer function is.
It looks like he's sticking to his guns on replicating transfer functions but he has gone to switching three voltage rails in or out for the power supply. When I saw the tube version with a forest of tubes each side of the main enclosure, I wondered why and what they were used for. When you explained the reasons for the ton of transistors in this solid state version, a light bulb went off in my head.
All these transistors have to be almost precisely replicating the tube design. If I remember correctly, each massive power output tube could output only a few tens of watts, e.g. 20, 30, 50, so you need that many to output 500-600 watts into speakers. There are more powerful tubes, but they cost the earth and probably are the power output for radio station transmitters! Anyway, it looks like Mr Carver is still wedded to switching electricity in some way.
Class D switching amplifiers are known to be efficient users of electricity, these mono amps certainly are NOT! I guess that's the price of catering to high end audiophiles. At least it's their power bill! This reminds me, could you find out what the initial power up does to the speaker output from the amp? If it's not too horrible or speaker destroying, just put a power switch on the power cord somehow. Your wallet and your feeling of safety will benefit!
The PS filter caps affect max continuous power as well as dynamic power. They have to hold up across mains half-cycles or you will clip, whether running a continuous or pulsed signal tone. Also its a class G amp, this is not particularly exotic to my mind.
I have found that symmetrical cascode more interesting than a traditional differential amplifier at a pre stage. I need more investigation what advantages are.
Still doesnt answer my internal burning question of why the transformer is smaller. My first thought is they were using the triac to frequency-double the 60Hz into 120Hz timed at the zero-cross so they could reduce the magnetics by two. But Maybe not? Even with that Class G/H-like topology, youre still going to need the same amount of power from the power supply to drive the load. I guess they arnt wasting as much power as heat due to the efficiency of the output stage itself? hmmm
The noise it will cause will be much higher than the 120Hz from the power mains. So, it should filter out pretty well. You just have to use components that still work at that frequency.
Very interesting. Since the value of those capacitors is critical, that makes the whole design extremely vulnerable. Stability of caps over time is a big issue, as we all know. This amp is a problem in permanent development.
The point to point mess in some areas of the board are very reminiscent of the kind of stuff you see in some boutique guitar amps. Just without tubes and done with no concern for visual presentation.
Actually stood for transfer function modified. Years ago Carver said he could take one of his solid state amplifiers and make it sound like a much more expensive amplifier of different designs. This was publisihised in Stereophile magazine and the end result was he succeeded. www.stereophile.com/content/carver-challenge This is the article he was a character and a brilliant engineer.
The mechanical equivalent of this is the commonly used in CVTs (Continuous Variable Transmissions) whereby the increased torque required by the load cause a pulley or a set of pulleys to expand in order to match the demand. This is just a ruff conceptional analogy - there is more physics to it!
soo...i cant see this amp sounding all that great. it looks like its just a normal complamentary pair output stage with a really complicated power supply.
Greetings: I know that you know that the outer ring of the probe BNC connectors are the 10x detector inputs. You meant to say that the probes BNC exterior connection is connected to the AC plug's safety ground. I find that telling junior engr.s that this method is like using the second probe input like the inverting input of an op amp.
Interesting how these amps don't even have a detached power cord?? The power cord on the Marantz 2500 receiver was TWICE as big - but Carver wants to be sure you use a "stiff AC supply...". Owned several Carver pcs. through the years and while they were OK, I agree with other comments that it just seemed like thier stuff was always just a showcase for B. Carver's ego.
+Embree Smith - Pretty sure a standard lighting circuit protected at 15A will carry 15A till the cows come home. It will carry an overload briefly (a la motor start) but will trip beyond that. In most homes, 20A is only used on appliance circuits.
Sorry, no residential breakers trip at 80% of the rated value, over time on an appliance start, it may be 170% of rated value I suggest you consult the N.E.C. for corroboration of these values NEC Sec. 384-16(c) NEC sizing rules. Secs. 210-22(c), 220-3(a), 220-10(b), and 384-16(c) all relate to the sizing rules for overcurrent protective devices (OCPDs). The first three all specify the same requirement: OCPD size = 100% of noncontinuous load + 125% of continuous load. Sec. 384-16(c) has the same requirement, except that it's stated in terms of the loading of the OCPD. This rule states that an OCPD can be loaded to only 80% of its rating for continuous loads. Remember that 80% is the inverse of 125% (0.80 = 1 [divided by] 1.25) and, as such, the rules are indeed identical in their end requirement. Read the rule closely; the 125% sizing of the OCPD (or 80% loading) is only applicable when continuous loads are involved. CBs and other OCPDs can be sized at 100% of their rating for noncontinuous load applications. In summary, a CB either carries a standard rating (80%) or a 100% rating. The standard rating is subject to the NEC sizing rules we've just discussed. CBs that are 100%-rated are permitted to be loaded continuously at their full rating as long as the assembly is listed and conductors are properly connected.
This is a three rail signal tracking power supply. Bob Carver did this before just about everyone else. He patented the continuously variable signal tracking power supply that is used in the Sunfire amps,but couldn't make it work. This was his sort of half assed attempt at a signal tracking power supply that did work. He later made the continuously variable signal tracking power supply work in the Lightstar amp before he go booted out of Carver Corp. then took it with him to Sunfire. The name Magnetic Field Power amplifier was just good marketing.
Tony- Earbud amp?? Those Carver amps should be able to power a PAIR of bluetooth speakers at background listening levels while you toast your marshmellows.
Parrt 1... so you'll be wearing a skull-and-bone hat and an eyepatch for this repair, then? :D All kidding aside, I just popped in to see what the thing in the thumbnail was, I'll have to watch the video later.
I admire the concept of and the thinking behind this amplifier, but it violates the KISS-principle in so many ways, I don't see how it could have ever been a commercially viable product.
Really? With the extreme mark-up available on high-end audio? Many companies rely on this! Yes its pretty byzantine, but if engineered properly that's not a show stopper. Still 10 pairs of 3281/1302's is pretty boggling.
Even with the available mark-up, making a temperamental, high-end amp with a stupid amount of power (seriously: have you ever been in a medium sized room with an amp actually sending 2 Watts RMS through a set of speakers? -it's absolutely deafening), isn't going to make you Bill Gates. These circuits rely soo much on components performing to spec, I'd be amazed if there's an all original one still working (even if it hadn't been used since new), which, in turn, to me, indicates a fair number of them would have never made it out of their warranty period. From an electronic design engineer's point of view, these circuits are a fun thought experiment, but just not a practical option. In construction, engineers design constructions 5x more sturdy than they, theorethically, need to be, just to be on the safe side. None of that was adhered to in this design. Also, if one's going to make a niche product at a high pricepoint, one creates an expectation of longevity, which this design can never live up to.
@@JVerschueren The high power is for the very short-term bursts of power. Many sounds you hear every day are very powerful for a split second, and the amp's high power is to reproduce this.
mikedrz This Amp was designed for people who have a few $100,000 to throw away. It drives those 8 ft high speakers (4 ohms) that needs a separate sound proof room in the house that you need to buy a bigger house for. It's a one in a million fool.
It certainly is, but what's the cost in terms of dollars per Watt? I don't even know what this unit costs, but I've seen it all before. Whenever something is built in such a creative way, the price tag is always up there.
0.5% THD is hardly impressive - quite poor for an expensive solid state amp actually. An interesting design for sure, but perhaps not a very good one..
I'm still trying to figure this one out. One thing I want to see is what the THD will be at a slightly reduced power (maybe 500 or 550 watts). Right now, that artifact that resembles crossover distortion is my main focus. We'll see what happens when I do the alignment. The power transformer also groans audibly when the amp is running at high power levels, probably because of the triac firing angle.
Well yes alright, if we assume that was the idea, then that result could have been accomplished much simpler. One way I know of: An unmatched input transistor pair can a give a nice 2nd harmonic on line level signal, to "warm" the sound. It could even be made adjustable with a knob on the front panel. Then the output stage just needs to have low distortion, so not to mess up the nice clean harmonics. Another point: Good push-pull tube amplifiers are quite linear and can have very low distortion - lower than this amp, but at lower power levels of course. It is only antique Single-ended Triode type designs, that typically have gross distortion of e.g. 2-5%. These primitive tube amps were already outdated by 1950, but have for some reason come back in favor with some audiophiles/fools in modern times :) So the so-called "Tube-Sound" kind of refers to 100 year old technology, and not to a well designed "modern" push-pull tube-amp.
Tony, I look forward to seeing how this repair turns out. Would be interesting to see an FFT of the output - I suspect there could be some unpleasant high-order harmonics in there.. Keep up the good work, and thanks for the tip on those industrial sized dummy load resistors. Will see if I can find those.
That thing is horrible! Those who have built their own power amplifiers will know that the most expensive parts are the power supply (transformer & big capacitors) and the heatsinks and this amplifier seriously skimps on both of those. It also appears that the design was prone to oscillation given the add-ons and those paralleled transistors (no ballast resistors) would be impossible to match which would cause harmonic distortion. And what about switching the higher voltages without causing some sort of transition? I am NOT convinced that this amplifier is good for anything to do with HiFi.
These were very well reviewed amps, and you are not paying for the amp, you are paying for all the research and development. Those were hand built , that is the $$$. Not for us normal people.
@@jero1836I have a pair. Sounds fantastic. Harry Pearson took a pair for review and never returned them because he liked them so much. So you don’t know what you’re talking about.
You can speed them up. RUclips provides a tool for that. I like to use Video Speed Controller (an add-on for Chrome and other browsers) so I can fine tune the speed. I find the default of 1.8x to be good.
Take breaks watching them, if you leave the video, when you come back it will start off where you left at before. Hope that helps. I like the long ones, its like getting 3 episodes at once. If need be ill leave the video and when I come back to it, it starts right up where it was at when I left.
My brother had two sets of these. Carver pulls the power out of the wall outlet rather than using big storage caps and big transformer. When you turn these up the lights will flicker badly with the draw of the amp unless you have a strong circuit. They really are loud. He also had a TFM-75 and that amp was two 750 watt mono blocks in one chassis, it was a bruit of an amp and those were very rare.
I seem to recall a review back in the day of Carver's "amazing" magnetic amplifier (the one that had a form factor of an 8" cube) and when they hit a particularly high output, the circuit breaker for the listening room tripped.
Well done! It was a long video but it showed clearly how this circuit works. thank you.
When the FTC put out their power ruling that required amplifiers be preconditioned by putting out 1/3 the rated power output for 1 hour before testing was started (circa 1975) the standard class AB amplifier was producing near maximum heat. They cooled down a little when run at full power after the preconditioning. Big amplifiers like the Phase Linear 700 would go into thermal shutdown several times accumulating 1 hour of run time. Then class G and H amplifiers started showing up. By selecting the lower voltage amplifier rails carefully they could run the 1/3 power preconditioning with the amplifier running at full power on the lower voltage rail, the higher voltage rails and transistors only ran during the full power test. This meant less heat sink and smaller power supplies. It was passed off as allowing more dynamic power (true) but the real reason was to get past the preconditioning requirement.
Carver improved on that by regulating the input to the power transformer with the triac as you have pointed out, and using additional rail voltages to produce a smaller more powerful amplifier for its physical size.
also
Thank you for the lesson on differential inputs.
I owned a pair of Silver 7ts back in the 90s. I used them to run a pair of Martin Logan Sequel IIs, driven by a Cary CAD5500 preamp. It sounded great and the amplifiers were so, so powerful - they froze up the woofers on my MLs at one point, and would regularly trip the circuit breaker in the house when going full tilt. I loved them. At least until a friend brought over a Conrad-Johnson MF200 which, while rated for way less power, did things in the bass that the Carvers just couldn't. They sounded weak by comparison (the 9ts would certainly have had a different sound). So I wound up trading them in for a CJ amp.
You are misinformed about the origin of the name, though. Bob Carver was a well-respected engineer at Phase Linear in the 70s and 80s, and in the mid-80s made a controversial statement that he had determined a way to measure the transfer function of any amplifier (this being a mathematical function that described the relationship between input and output of an amplifier, i.e., a function that describes the sound of an amplifier) and further that he knew how to modify an amplifier's transfer function so that he could make any amplifier sound like any other, including extremely high-end amps. The tweaky audio press at the time thought he was crazy as I recall, but he got a couple of magazines to accept a challenge and it was generally agreed that he managed to duplicate the sound of both a high-end Mark Levinson and Conrad Johnson amplifier with one of his relatively cheap amps, which would have been the predecesor to these Silver 9ts. The original modified amp went on the market and sold as the M1.5t, which stood for Magnetic Field Amplifier, 1.5kw, transfer function modified - thus the "t" in the model number.
He did a couple of other amps including an inexpensive M400t, and then created a statement tube amplifier as a way to set the ultimate target for his "transfer modifying" technology. This was the Silver Seven, and the audiophile press of the day collectively shat itself over the amplifier. Few were sold, as it was really made to give him something to copy, and so he produced the Silver 7t, which was a (relatively) inexpensive, solid-state amp that was supposed to sound exactly like the Silver Seven. As I recall it sold fairly well, but had relatively low current capability, which explains the Silver 9t with its higher damping factor and more sophisticated power supply.
I don't know if he ever revealed what the secret was to modifying the transfer function but I have to wonder if those tacked-on resistors, capacitors, and transistors on the amp board don't have something to do with it - maybe it was a modification they made on an individual basis to each amp that left the factory?
+ Alan Westenbrook - Your account agrees with my addled memory. Bob Carver is part genius and part huckster, but nobody could deny his creations worked, if in alarming ways.
I really like the dummy loads and I could hear the tone when you had the power up. Those amps are beasts.
I've owned my Silver 9t's for over 30 years! Still working flawless and driving my Legacy Focus Speakers, I hang out at local hifi store a lot. They're flagship amps are Classe. Still wouldn't trade even up! Best amps still.
I still own a pair of these. I bought them used in the late 80's. I had them hooked up to a pair of magnapan tympani speakers, they sounded great for a while. Then something went wrong and the tweeter panel on the left speaker caught on fire so I boxed them up and haven't used them since. I would like to use them again.
Very interesting. Thanks for posting. I have a pair I use in my home theatre to drive subwoofers. An interesting sidenote. At the time these came out I had another power amplifier that put out almost the same power. I'm old ha ha, any way my speakers were a very tough load 4 ohms dropping to two and the only amp I found at the time was a sound craftsman. It was called a class "H" House lights kept time with the music!
What's interesting is that I have a Carver M-4.0T amp, which uses basically the same circuit, but with half the number of output transistors per circuit board. Because of the odd way the second row of transistors is installed here, not to mention other components, it almost seems to me like the 9T took the circuit board (which appears to be the exact same PCB) from one of their stereo amps and "adapted" it as a mono amp. This would explain why you have components tacked on both sides of the board.
On mine, quite a few of the smaller PCB-mounted electrolytic capacitors were showing definite signs of age.
Thanks again, as always very interesting
I think this kind of amps can be called class g, works with varying voltages per demand.
Using the triac ( which can be switched no more than 120 times a second) to stabilize the voltage looks like an early version of SMPS which would probably be used today
If you connect these silver 9s to a standard 15 amp residential power line be prepared to trip the 15 amp breaker regularly due to Bob not using high capicity Caps in the design to be called on to supply up to 10x wattage for transient peaks ,I had to install dual dedicated 20 amp lines to supply the power from the wall to these ,the Carver monoblocks require more power from the wall than my McIntosh Mc-1201 1,200 8ohm watt monoblocks,or my Krell FPB 750s that push over 800 class A watts per channel .
"I dunno whether to like it or not. I *respect* it, though."
I remember having precisely the same feeling. It was after a long day of backpacking, and finally we made it to our campsite, where we encountered a big ol' rattlesnake. He loudly announced his presence, coiled up a couple feet high, smack in the middle of the firepit, in *our* campsite. Well... it was *supposed* to be our campsite; suddenly it wasn't.
Love your videos man! Often when I´m working I am just listening haha
I used to work with a couple of engineers who had mains leads for there scopes with the earth taken out, this was marked on the plug ! I guess thats one way ? this amp better sound fantastic, I found the automatic gearbox analogy useful...cheers!
a super bass surge would make lights go out ur circut breakers click lol i love these beast ! a little scary they be great for a stadium sound lol !
I love how you explane things your work is amazing
that high voltage end of the power supply where the triac is, that reminds of a PWM power supply, the same power supply used in computers, but with a much slower speed than the computers power supply
Very interesting video of an unusual amplifier. Thanks.
fantastic video once again.....thanks for sharing your wisdom and knowledge. :);
It's Class G amplifier, used mostly on pro amplifier. Yamaha also used this design on hifi amplifier the Yamaha AST-A10 so what they called Active Servo Amplifier.
My guess by the design of the power supply and the amplifier section layouts are that Bob Carver was trying to make an 'On Demand" Amplifier rather than a "constant on" Amplifier/Heater for cooler running theory.
bob carver was way a head of his time
Interesting design. I can see how it would be more efficient. I also wonder if it would have a better dampening factor (low output impedance) before the negative feedback. My thought being the higher the "resistance" the output transistors have between the speaker and the power rail, the higher it's natural output impedance. So, with a high voltage power rail and low output levels, the uncorrected output impedance would be rather high. But with lower voltage power rails, then the transistor opens up more for the same output power - and you have a lower output impedance.
The “t” stood for Transfer Function Modified, Bob Carver’s way of making a transistor amp replicate the sound of a tube amp.
I was wondering what it really meant. I knew it had to do with tube sound. Thanks!
I remember some of Bob Carver's early designs in the 1980s. They were all solid state and the low height of the case would not allow for a large transformer. They must have used switching power supplies. The audiophile reviewers disliked them. Carver's comeback was "Give me the transfer function of your favorite tube amp and I'll replicate it on my amp." I don't think he succeeded the first time, but he did get closer. I was interested since I had just learned what a transfer function is.
It looks like he's sticking to his guns on replicating transfer functions but he has gone to switching three voltage rails in or out for the power supply. When I saw the tube version with a forest of tubes each side of the main enclosure, I wondered why and what they were used for. When you explained the reasons for the ton of transistors in this solid state version, a light bulb went off in my head.
All these transistors have to be almost precisely replicating the tube design. If I remember correctly, each massive power output tube could output only a few tens of watts, e.g. 20, 30, 50, so you need that many to output 500-600 watts into speakers. There are more powerful tubes, but they cost the earth and probably are the power output for radio station transmitters! Anyway, it looks like Mr Carver is still wedded to switching electricity in some way.
Class D switching amplifiers are known to be efficient users of electricity, these mono amps certainly are NOT! I guess that's the price of catering to high end audiophiles. At least it's their power bill! This reminds me, could you find out what the initial power up does to the speaker output from the amp? If it's not too horrible or speaker destroying, just put a power switch on the power cord somehow. Your wallet and your feeling of safety will benefit!
The PS filter caps affect max continuous power as well as dynamic power. They have to hold up across mains half-cycles or you will clip, whether running a continuous or pulsed signal tone. Also its a class G amp, this is not particularly exotic to my mind.
FINALLY! Some CARVER gear. There is really nothing technically on all of you tube. Puzzling since the brand has a dedicated website and following.
I have found that symmetrical cascode more interesting than a traditional differential amplifier at a pre stage. I need more investigation what advantages are.
very interesting tony, i personally never seen one of these.
Exactly the design quality appropriate for my microwave owen - nothing like propper audio IMO.
I don't think the electrons mind about the aesthetics, it works or it doesn't! I'd like more connectors so its easier to take apart for working on it.
Thanks for the detailed staging explanation.
Crossover distortion shows up more at low power levels.
I guess your point was that this is a Class D, or perhaps Class I switching amp
like my Crown K2 balanced current amplifier
Great job! I was able to keep up with your explanation perfectly !!
bob carver made good amps like the phase linear amps
That's a heck of a headphone amp! lol!
Is this like a switch mode power supply that chord amps use??
Still doesnt answer my internal burning question of why the transformer is smaller. My first thought is they were using the triac to frequency-double the 60Hz into 120Hz timed at the zero-cross so they could reduce the magnetics by two. But Maybe not? Even with that Class G/H-like topology, youre still going to need the same amount of power from the power supply to drive the load. I guess they arnt wasting as much power as heat due to the efficiency of the output stage itself? hmmm
Great explanation, thank you.
Hitachi used a variation of this in the late 70's with stacked outputs, but only 2 layers.
triac...wont that cause noise in the power supply?
That's my initial thought. We'll see!
The noise it will cause will be much higher than the 120Hz from the power mains. So, it should filter out pretty well. You just have to use components that still work at that frequency.
Very interesting. Since the value of those capacitors is critical, that makes the whole design extremely vulnerable. Stability of caps over time is a big issue, as we all know. This amp is a problem in permanent development.
The point to point mess in some areas of the board are very reminiscent of the kind of stuff you see in some boutique guitar amps. Just without tubes and done with no concern for visual presentation.
This is something like the Germans would build? Uber engineered!!!!
Actually stood for transfer function modified. Years ago Carver said he could take one of his solid state amplifiers and make it sound like a much more expensive amplifier of different designs. This was publisihised in Stereophile magazine and the end result was he succeeded.
www.stereophile.com/content/carver-challenge
This is the article he was a character and a brilliant engineer.
Those could send your ear buds into orbit.
I wan’t to buy one of those dummy loads. Can you add the link to the dummy load resistor and the single shielded O-scope probes. Thanks
How about using it just with +/- 67v and +/- 31v to have just 100w to 150W of it. I won't dare to play it as it is after 20 years of use
Thanks for the video and information.
Things start to get kind of strange @ 34:59 .. LOL LOL .
Superb twins
Do you still work on Carver TFM amps?
The mechanical equivalent of this is the commonly used in CVTs (Continuous Variable Transmissions) whereby the increased torque required by the load cause a pulley or a set of pulleys to expand in order to match the demand. This is just a ruff conceptional analogy - there is more physics to it!
soo...i cant see this amp sounding all that great. it looks like its just a normal complamentary pair output stage with a really complicated power supply.
I wonder if old Bob Carver ever met Mr Tim Leary...? o_0
While you are at it you real should replace that Triac before it fails
Greetings:
I know that you know that the outer ring of the probe BNC connectors are the 10x detector inputs. You meant to say that the probes BNC exterior connection is connected to the AC plug's safety ground.
I find that telling junior engr.s that this method is like using the second probe input like the inverting input of an op amp.
That helps to visualise it...cheers.
37:54 - ElectroBoom woke up, lol.
Interesting how these amps don't even have a detached power cord?? The power cord on the Marantz 2500 receiver was TWICE as big - but Carver wants to be sure you use a "stiff AC supply...". Owned several Carver pcs. through the years and while they were OK, I agree with other comments that it just seemed like thier stuff was always just a showcase for B. Carver's ego.
That power switch idea makes no sense to me.
That is wild.
got crossover distortion may be the bias is out
Your Breaker, if say, 20 A
should trip at 80% of the value after some continued loading
I'm pretty sure your neighbors will have called the cops before then. ;)
+Embree Smith - Pretty sure a standard lighting circuit protected at 15A will carry 15A till the cows come home. It will carry an overload briefly (a la motor start) but will trip beyond that. In most homes, 20A is only used on appliance circuits.
Sorry, no
residential breakers trip at 80% of the rated value, over time
on an appliance start, it may be 170% of rated value
I suggest you consult the N.E.C. for corroboration of these values
NEC Sec. 384-16(c)
NEC sizing rules. Secs. 210-22(c), 220-3(a), 220-10(b), and 384-16(c)
all relate to the sizing rules for overcurrent protective devices
(OCPDs). The first three all specify the same requirement:
OCPD size = 100% of noncontinuous load + 125% of continuous load.
Sec. 384-16(c) has the same requirement, except that it's stated in
terms of the loading of the OCPD. This rule states that an OCPD can be
loaded to only 80% of its rating for continuous loads. Remember that 80%
is the inverse of 125% (0.80 = 1 [divided by] 1.25) and, as such, the
rules are indeed identical in their end requirement.
Read the rule closely; the 125% sizing of the OCPD (or 80% loading)
is only applicable when continuous loads are involved. CBs and other
OCPDs can be sized at 100% of their rating for noncontinuous load
applications.
In summary, a CB either carries a standard rating (80%) or a 100%
rating. The standard rating is subject to the NEC sizing rules we've
just discussed. CBs that are 100%-rated are permitted to be loaded
continuously at their full rating as long as the assembly is listed and
conductors are properly connected.
Emree - Impressive knowledge of the NEC rule book, congrats.
This is a three rail signal tracking power supply. Bob Carver did this before just about everyone else. He patented the continuously variable signal tracking power supply that is used in the Sunfire amps,but couldn't make it work. This was his sort of half assed attempt at a signal tracking power supply that did work. He later made the continuously variable signal tracking power supply work in the Lightstar amp before he go booted out of Carver Corp. then took it with him to Sunfire. The name Magnetic Field Power amplifier was just good marketing.
Tony- Earbud amp?? Those Carver amps should be able to power a PAIR of bluetooth speakers at background listening levels while you toast your marshmellows.
oh man thats funny 575ch those are house pounders lol real monsters !!
This is crazy shit, but you did explain it pretty good... i think!
Parrt 1... so you'll be wearing a skull-and-bone hat and an eyepatch for this repair, then? :D
All kidding aside, I just popped in to see what the thing in the thumbnail was, I'll have to watch the video later.
Strange! Interesting!
I run four restored Silver 7t amps in my home stereo. No lacking power!
$920 for a pair of Carver Silver 9T's on eBay.
cool
500+Watts per channel is not 'nough for my headphonez. need moar powarrrr!
I admire the concept of and the thinking behind this amplifier, but it violates the KISS-principle in so many ways, I don't see how it could have ever been a commercially viable product.
Really? With the extreme mark-up available on high-end audio? Many companies rely on this! Yes its pretty byzantine, but if engineered properly that's not a show stopper. Still 10 pairs of 3281/1302's is pretty boggling.
Even with the available mark-up, making a temperamental, high-end amp with a stupid amount of power (seriously: have you ever been in a medium sized room with an amp actually sending 2 Watts RMS through a set of speakers? -it's absolutely deafening), isn't going to make you Bill Gates.
These circuits rely soo much on components performing to spec, I'd be amazed if there's an all original one still working (even if it hadn't been used since new), which, in turn, to me, indicates a fair number of them would have never made it out of their warranty period. From an electronic design engineer's point of view, these circuits are a fun thought experiment, but just not a practical option. In construction, engineers design constructions 5x more sturdy than they, theorethically, need to be, just to be on the safe side. None of that was adhered to in this design.
Also, if one's going to make a niche product at a high pricepoint, one creates an expectation of longevity, which this design can never live up to.
@@JVerschueren The high power is for the very short-term bursts of power. Many sounds you hear every day are very powerful for a split second, and the amp's high power is to reproduce this.
And i found an error in this video:-)))))) Who saw it too ?
Well from what I see they make excelenr value for people who park cars on a slope, to put it under the wheel.
er, what's going on?
Just audiophoolery
mikedrz This Amp was designed for people who have a few $100,000 to throw away. It drives those 8 ft high speakers (4 ohms) that needs a separate sound proof room in the house that you need to buy a bigger house for. It's a one in a million fool.
Julia M They are marketed as a "lifestyle" instead of overpriced audio equipment. Haha
mikedrz 575 watts is some serious juice. I owned a TFM 25 amp and it was amazingly powerful.
It certainly is, but what's the cost in terms of dollars per Watt? I don't even know what this unit costs, but I've seen it all before. Whenever something is built in such a creative way, the price tag is always up there.
0.5% THD is hardly impressive - quite poor for an expensive solid state amp actually. An interesting design for sure, but perhaps not a very good one..
I'm still trying to figure this one out. One thing I want to see is what the THD will be at a slightly reduced power (maybe 500 or 550 watts). Right now, that artifact that resembles crossover distortion is my main focus. We'll see what happens when I do the alignment. The power transformer also groans audibly when the amp is running at high power levels, probably because of the triac firing angle.
Jonas vH. Berg isn't it the idea to add distortion to represent the function of a tube?
Not crossover, that is the nemesis of distortions.
Well yes alright, if we assume that was the idea, then that result could have been accomplished much simpler. One way I know of: An unmatched input transistor pair can a give a nice 2nd harmonic on line level signal, to "warm" the sound. It could even be made adjustable with a knob on the front panel. Then the output stage just needs to have low distortion, so not to mess up the nice clean harmonics.
Another point: Good push-pull tube amplifiers are quite linear and can have very low distortion - lower than this amp, but at lower power levels of course. It is only antique Single-ended Triode type designs, that typically have gross distortion of e.g. 2-5%. These primitive tube amps were already outdated by 1950, but have for some reason come back in favor with some audiophiles/fools in modern times :) So the so-called "Tube-Sound" kind of refers to 100 year old technology, and not to a well designed "modern" push-pull tube-amp.
Tony, I look forward to seeing how this repair turns out. Would be interesting to see an FFT of the output - I suspect there could be some unpleasant high-order harmonics in there..
Keep up the good work, and thanks for the tip on those industrial sized dummy load resistors. Will see if I can find those.
That thing is horrible! Those who have built their own power amplifiers will know that the most expensive parts are the power supply (transformer & big capacitors) and the heatsinks and this amplifier seriously skimps on both of those. It also appears that the design was prone to oscillation given the add-ons and those paralleled transistors (no ballast resistors) would be impossible to match which would cause harmonic distortion. And what about switching the higher voltages without causing some sort of transition?
I am NOT convinced that this amplifier is good for anything to do with HiFi.
What a crap 20.000 USD hah, nice video though thumbs up. but Carver jeeez
These were very well reviewed amps, and you are not paying for the amp, you are paying for all the research and development. Those were hand built , that is the $$$. Not for us normal people.
Yes and very poorly hand build with crappy components, like transformer etc its just aweful and a rip off imho
@@jero1836I have a pair. Sounds fantastic. Harry Pearson took a pair for review and never returned them because he liked them so much. So you don’t know what you’re talking about.
I have to say that amp is built like a salt water pool chlorinator power supply......bloody awful...... dead bug construction would be better....
Really funny not
Rediculously over engineered. FAR more things to go wrong. Bad engineering. The designer was just showing off.
I think Bob Carver was a showoff but a brilliant man.
Unique design? Maybe. Good design? No.
Ok RUclips “expert”.
These videos are excessively to long , please edit them down for time
Why don't you shut up?
You can speed them up. RUclips provides a tool for that. I like to use Video Speed Controller (an add-on for Chrome and other browsers) so I can fine tune the speed. I find the default of 1.8x to be good.
trigger response
Take breaks watching them, if you leave the video, when you come back it will start off where you left at before. Hope that helps. I like the long ones, its like getting 3 episodes at once. If need be ill leave the video and when I come back to it, it starts right up where it was at when I left.
Why don't you get lost?