Recently purchased a set of these amps. Your video is most informative and your way of discussion is enlightening and easy to follow. Thanks for all your work!
Very good analysis job..... more than very good..... excellent job....i thank you very much by this video that clarified my understanding about this set.
Xray Tony - I LOVE your videos. My electronics experience is limited to CB radio and some heath kits when I was a kid. I'm an architect/designer and I have your videos playing on my pad when I'm drafting. You're an amazing presenter. Thanks!
Yes, do check the other amp and see how it compares. Troubleshooting this amp further, I'd look to see if the power rails are holding up symmetrically and if the commutator is switching in both sides at once. As for the unbalanced idle current, I'd think I'd look to see what component is "unmatched" rather then attempt to add an adjustment. I'm thinking an adjustment would just be a cover-up for the real issue.
Oh dear, when Carvers have issues.......time to take stock, bunker in and twist your mind.....I am a veteran of PM1.5, PM1200, PM2400, PT1250, PM2.0.....wait until you get a PT1250 across your bench....They are hilarious in design, you are entering the mind of a twisted genius when servicing and repairing!!
Correct me if I'm wrong, but I think I'd call this a Class G with a primary power supply regulation. Without re-watching PT1, I don't think the triac is modulated with the input signal (at least not directly), but rather it's responding to the power supply voltage (regulating). In fact, I hesitate to call it a regulator. Because it acts on the primary, it can only correct at a rate of 120 times per second. (As opposed to a switching power supply which might be 100K times, or a analog which would still have a slew rate well above 120 times.) I think of it more as power line compensation/stabilization (although it also can compensate for the drops in the primary side of the power supply.) The rest of the power supply is going to look traditional since the caps are charged every 120 times a second and the amp runs off the caps for the rest of the AC waveform.
I agree with some of the other comments i believe if the rail voltage is stable and the commutation timing is even then i would be looking at the HFE of the OP's and the drivers and try to balance it that way . good video as always !!
You can put a dab of alcohol on a q-tip and then on each trans and diode and if evaporates faster you know which is running hotter if you don't have a thermal camera, which I don't.
Did the lights semi-dim with amplifier peak signal power draw? If so, Bob Carver may have wanted a 'living amp' ambience to the lighting scheme? Thus the need for incandescent bulbs. Just a guess though.
As far as the meter lights are concerned, my guess is that your circuit for them is on a higher voltage rail to keep noise out the low level sound circuit, you're much less likely to hear it at higher volumes. More above if any.
Floating ground? That would explain using the positive and negative rails. You probably mentioned if it floats or not, me missing that on my first go thru would be typical.
Interesting amp - I suspect one of the commutator sections or commutating diodes is blown - have you got a thermal camera, they really help spot faults, especially with an asymmetry where you know the two sides should be basically the same (+ve v. -ve rail). Either the high voltage rail isn't being commutated properly through the transistors, or the diode is short so it commons the high and middle rails rather than switching over?
Nice video, good information, did I follow it well? Maybe. Must comment about dictation. In audio when listening to music (music being made up of Harmonics) through an audio system, the killer of the sound is caused by Intermodulation distortion, a little harmonic dictation may add to the joy of listening. One of the main problem of changing over from tube amplifiers to transistors amp., was high intermodulation distortion of the transistors along with transistor noise. I believe tubes have a higher harmonic distortion then transistors, and for that reason musicians like tube amps over transistors amps. Carver's amps are all about head room for pike pulses, I had a Phase Liner 400 amp and in the manual it stated that it was meant to give 50 RMS watts per channel with a lot of head room for pile musical pulses. Other things to say, but this will do.
supposedly Yamaha licensed a similar technology in the early 1980s from Carver to make what they called "X-Power" using a similar pulse power and a TRIAC element in their B-6 amplifier, but Carver claimed that Yamaha did not have the rights to the technology and the B-6 was the only amplifier Yamaha ever made using these "pulse-TRIAC" amplifier technology that would later be used in Carver's Silver series.
It does everything its supposed to do until you measure the sound quality, I am anything BUT an expert, however the emperors new cloths comes to mind with these 'high end' revolutionary 'brilliant' amps, and no way to tweak it, fascinating series though ! ...no to watch the next one ...cheers.
Something still wrong with that amp. I have worked on many Carver TFM , 1.5, and cubes amplifiers which are essentially the same in design. It should not clip that way or have that kind of thd. When working they will clip very symmetrically
Couldn't the incandescent bulbs you talked about in the beginning be a amperage rectifier for the DC officer to keep the mains voltage regulated, What about thermally coupling the transistors would this help. There must be something to regulate the DC offset, could it be anything to do with the capacitors you changed? why did you need to change them for?
@@andymouse I am assuming these were very experimental amps in the way of design and because they were engineered so differently that they could sell them at a high price during the time?
Seems like the way they manage power is a primitive simple switch my power supply my electronics experience is limited I’m just a beginner but is my assumption in the general right ballpark?
I agree... a 'poor mans' SwitchModePowerSupply... most circuit designers would NEVER design an SMPS into an audiophile audio amplifier. All of those splikey, high-speed voltage transitions can cause hard to filter noise.
This amp design looks like it had been "designed by poking". Getting an idea and the starting to develop and modify it until it kinda works. Like having those transistors in parallel: Ususally one transistor takes most of the current and the other one just doesn't do anything really. And the lighting circuit. And worst thing is probably the triac thing. To make anything like that working properly needs a proper design and anlysis. And rigid AC input. And if AC input requirements are not stated, it is difficult know how it should perform. On your specific problem on the negative side, the soft clipping: The whole power amp section is emitter follower circuit. I would look into the signal levels of the preceding stage to see if that clipping happens there.
Strange lighting circuit. Unless they need that as a load I would disconnect the negative side and connect to ground. Just reconfigure it to work off 31 volts instead of 62.
Be interesting if the other amplifier has the same issue. I cannot be leave an amplifier of this price has such a poor performance.Not really sure who would use that kind of power, even at the rated distortion, it is does not offer any kind of quality performance, just lots of grunt!
As several others have already said, something's still wrong with this guy. Can't hurt to check for bad resistors, commutating diodes or resistors in the suspect area.
Put simply, this appears to be a 'poor mans' switching powersupply keeping those huge caps charged based on amplifier demands. Knowing that switching powersupplies are VERY sensitive to capacitor ESR... can we assume you will be testing those huge capacitors?
When I bought these amplifiers they told me to buy 2.5 kva 1:1 isolation transformers along with a ac capacitor bank. I did and they still malfunctioned.
@Fred Johnson Bought virtually all his solid state models looking for one that sounded good. Bought the 500t cuz the meters looked cool. Worst sounding amp on the planet!!
@Fred Johnson U miss quote me, didn’t say I’ve owned all, said virtually all. The TFM series are not true Carver amps as they were products of Carver Corp after Bob left the company. I never owned a TFM series amp. Gave up on Carver after owning the 400a, 500t, and twin 1.0’s. All original Carver magnetic field designs.
What a piece of shit (the lack of quality construction and bodges). But then again, Bob Carver was/is such an eccentric want to be "engineer". Stupid money spent on anyone who owns these amp, IMO.
Romany1111 - Yes, he may be very competent as a amplifier designer, but the construction quality of this amplifier is appalling! Afterthought components tacked on here and there?? - I don’t believe that is acceptable. And an amplifier of this prodigious power output not having a proper mains off switch?? Again how hard would that have been to incorporate?? I do acknowledge that it is a clever and efficient design, but it’s construction leaves a lot to be desired.
Carver’s stuff does tend to measure noisy due to the power supply. Same with the sunfire stuff he did even though its power supply works differently. I think when brand new they might measure better but over time any drift in capacitors, rectifiers and typically many many op amps increase the noise. Carver was never very concerned with construction quality. The mainline stuff at least had the economy of manufacturing forcing some rationality but this thing seems essentially at the prototype stage. The sunfire stuff has a bit of the homemade look to it as well in the power supply and the speaker jack output wiring And this is just trying to to get too much power out of the electrical circuit in the house.
A sunday morning, a mug of coffee and video of Tony. That's life.
Recently purchased a set of these amps. Your video is most informative and your way of discussion is enlightening and easy to follow. Thanks for all your work!
Very good analysis job..... more than very good..... excellent job....i thank you very much by this video that clarified my understanding about this set.
Xray Tony - I LOVE your videos. My electronics experience is limited to CB radio and some heath kits when I was a kid. I'm an architect/designer and I have your videos playing on my pad when I'm drafting. You're an amazing presenter. Thanks!
The best designs are the simple designs. Simplicity + Quality Parts = Reliabilty ..
KISS!
The acronym " KISS " means .. " Keep It Simple Stupid " .
4:16 - "Hotter than a $2 pistol!" - a phrase I learned at a tender age from my mother, lol.
Excellent video Tony I would not have an amp like this all i can say about it is it would make a good welder. Great job.
Yes, do check the other amp and see how it compares. Troubleshooting this amp further, I'd look to see if the power rails are holding up symmetrically and if the commutator is switching in both sides at once. As for the unbalanced idle current, I'd think I'd look to see what component is "unmatched" rather then attempt to add an adjustment. I'm thinking an adjustment would just be a cover-up for the real issue.
That was fantastic, thanks, man! I loved both parts!
Oh dear, when Carvers have issues.......time to take stock, bunker in and twist your mind.....I am a veteran of PM1.5, PM1200, PM2400, PT1250, PM2.0.....wait until you get a PT1250 across your bench....They are hilarious in design, you are entering the mind of a twisted genius when servicing and repairing!!
Correct me if I'm wrong, but I think I'd call this a Class G with a primary power supply regulation. Without re-watching PT1, I don't think the triac is modulated with the input signal (at least not directly), but rather it's responding to the power supply voltage (regulating). In fact, I hesitate to call it a regulator. Because it acts on the primary, it can only correct at a rate of 120 times per second. (As opposed to a switching power supply which might be 100K times, or a analog which would still have a slew rate well above 120 times.) I think of it more as power line compensation/stabilization (although it also can compensate for the drops in the primary side of the power supply.) The rest of the power supply is going to look traditional since the caps are charged every 120 times a second and the amp runs off the caps for the rest of the AC waveform.
I agree with some of the other comments i believe if the rail voltage is stable and the commutation timing is even then i would be looking at the HFE of the OP's and the drivers and try to balance it that way . good video as always !!
You can put a dab of alcohol on a q-tip and then on each trans and diode and if evaporates faster you know which is running hotter if you don't have a thermal camera, which I don't.
That's a great tip (no pun intended)! If you don't mind, I will try to mention it in a future video. Thanks for watching!
Thank you for this video.
Did the lights semi-dim with amplifier peak signal power draw? If so, Bob Carver may have wanted a 'living amp' ambience to the lighting scheme? Thus the need for incandescent bulbs. Just a guess though.
As far as the meter lights are concerned, my guess is that your circuit for them is on a higher voltage rail to keep noise out the low level sound circuit, you're much less likely to hear it at higher volumes. More above if any.
Floating ground? That would explain using the positive and negative rails. You probably mentioned if it floats or not, me missing that on my first go thru would be typical.
Interesting amp - I suspect one of the commutator sections or commutating diodes is blown - have you got a thermal camera, they really help spot faults, especially with an asymmetry where you know the two sides should be basically the same (+ve v. -ve rail). Either the high voltage rail isn't being commutated properly through the transistors, or the diode is short so it commons the high and middle rails rather than switching over?
Nice video, good information, did I follow it well? Maybe. Must comment about dictation. In audio when listening to music (music being made up of Harmonics) through an audio system, the killer of the sound is caused by Intermodulation distortion, a little harmonic dictation may add to the joy of listening. One of the main problem of changing over from tube amplifiers to transistors amp., was high intermodulation distortion of the transistors along with transistor noise. I believe tubes have a higher harmonic distortion then transistors, and for that reason musicians like tube amps over transistors amps. Carver's amps are all about head room for pike pulses, I had a Phase Liner 400 amp and in the manual it stated that it was meant to give 50 RMS watts per channel with a lot of head room for pile musical pulses. Other things to say, but this will do.
supposedly Yamaha licensed a similar technology in the early 1980s from Carver to make what they called "X-Power" using a similar pulse power and a TRIAC element in their B-6 amplifier, but Carver claimed that Yamaha did not have the rights to the technology and the B-6 was the only amplifier Yamaha ever made using these "pulse-TRIAC" amplifier technology that would later be used in Carver's Silver series.
It does everything its supposed to do until you measure the sound quality, I am anything BUT an expert, however the emperors new cloths comes to mind with these 'high end' revolutionary 'brilliant' amps, and no way to tweak it, fascinating series though ! ...no to watch the next one ...cheers.
Something still wrong with that amp. I have worked on many Carver TFM , 1.5, and cubes amplifiers which are essentially the same in design. It should not clip that way or have that kind of thd. When working they will clip very symmetrically
This thing looks like something out of a horror movie. OOOOOOO
I looks like it is 'soft-clipping' on the negative side. I would consider at least one transistor saturating way out of spec.
Great video. Unusual amp!! Good design? Well.........
Couldn't the incandescent bulbs you talked about in the beginning be a amperage rectifier for the DC officer to keep the mains voltage regulated,
What about thermally coupling the transistors would this help. There must be something to regulate the DC offset, could it be anything to do with the capacitors you changed? why did you need to change them for?
I have just bought a pair of those amp
At this point in the series, you have my condolences.
@@andymouse I am assuming these were very experimental amps in the way of design and because they were engineered so differently that they could sell them at a high price during the time?
Maybe there's a voltage surge at switch on, so the lamps need protecting, hence zeners and resistor?
Just guessing but if there is such a surge I would expect the whole amp to self destruct at switch on.
LED illumination for meter - possibility of RF hash being introduced into the audio? Remote, but new incandescents should last another 30 years
LED doesn't automatically mean RF hash. It would be a function of how you drop the voltage.
You need to check the 'bootstrap' circuitry on the positive side. it is clipping way to early.
Does this use a different transformer on 240V or does it automagically turn down the TRIAC duty cycle?
Seems like the way they manage power is a primitive simple switch my power supply my electronics experience is limited I’m just a beginner but is my assumption in the general right ballpark?
I agree... a 'poor mans' SwitchModePowerSupply... most circuit designers would NEVER design an SMPS into an audiophile audio amplifier. All of those splikey, high-speed voltage transitions can cause hard to filter noise.
This amp design looks like it had been "designed by poking". Getting an idea and the starting to develop and modify it until it kinda works. Like having those transistors in parallel: Ususally one transistor takes most of the current and the other one just doesn't do anything really. And the lighting circuit. And worst thing is probably the triac thing. To make anything like that working properly needs a proper design and anlysis. And rigid AC input. And if AC input requirements are not stated, it is difficult know how it should perform.
On your specific problem on the negative side, the soft clipping: The whole power amp section is emitter follower circuit. I would look into the signal levels of the preceding stage to see if that clipping happens there.
Strange lighting circuit. Unless they need that as a load I would disconnect the negative side and connect to ground. Just reconfigure it to work off 31 volts instead of 62.
But you'd unbalance the load on the power supply! (tongue in cheek)
Be interesting if the other amplifier has the same issue. I cannot be leave an amplifier of this price has such a poor performance.Not really sure who would use that kind of power, even at the rated distortion, it is does not offer any kind of quality performance, just lots of grunt!
As several others have already said, something's still wrong with this guy. Can't hurt to check for bad resistors, commutating diodes or resistors in the suspect area.
What provides the precise symmetry through the amp to the outputs?
5% distortion sound like a guitar amp mode ? Something badly wrong here, have check each diode that isolates high voltage and low voltage rail
This makes a tried and true Adcom GFA-555 power amp look like a piece of art work buy comparison..
Put simply, this appears to be a 'poor mans' switching powersupply keeping those huge caps charged based on amplifier demands. Knowing that switching powersupplies are VERY sensitive to capacitor ESR... can we assume you will be testing those huge capacitors?
What poor man could afford this amp? :)
When I bought these amplifiers they told me to buy 2.5 kva 1:1 isolation transformers along with a ac capacitor bank. I did and they still malfunctioned.
Carver amps make for good boat anchors. I know, I’ve owned more than just one.
Why would you buy a second one if the first was a "boat anchor"
@Fred Johnson
Bought virtually all his solid state models looking for one that sounded good. Bought the 500t cuz the meters looked cool. Worst sounding amp on the planet!!
@@Carl-bd1rf having owned all his solid state models, what are your thoughts on the difference between the TFM-35 and TFM-35x?
@Fred Johnson
U miss quote me, didn’t say I’ve owned all, said virtually all.
The TFM series are not true Carver amps as they were products of Carver Corp after Bob left the company. I never owned a TFM series amp. Gave up on Carver after owning the 400a, 500t, and twin 1.0’s. All original Carver magnetic field designs.
@@Carl-bd1rf I recommend that you listen to the TFM-35x or TFM-55x, maybe you'll find what you are looking for...
What a piece of shit (the lack of quality construction and bodges). But then again, Bob Carver was/is such an eccentric want to be "engineer". Stupid money spent on anyone who owns these amp, IMO.
The Elon Musk of audio?
Idiotic comment. Carver is a degreed (M.S.) physicist and EE. And his designs are some of the best out there, at any price. You're out of your league.
Romany1111 - Yes, he may be very competent as a amplifier designer, but the construction quality of this amplifier is appalling! Afterthought components tacked on here and there?? - I don’t believe that is acceptable. And an amplifier of this prodigious power output not having a proper mains off switch?? Again how hard would that have been to incorporate?? I do acknowledge that it is a clever and efficient design, but it’s construction leaves a lot to be desired.
Carver’s stuff does tend to measure noisy due to the power supply. Same with the sunfire stuff he did even though its power supply works differently. I think when brand new they might measure better but over time any drift in capacitors, rectifiers and typically many many op amps increase the noise.
Carver was never very concerned with construction quality. The mainline stuff at least had the economy of manufacturing forcing some rationality but this thing seems essentially at the prototype stage. The sunfire stuff has a bit of the homemade look to it as well in the power supply and the speaker jack output wiring
And this is just trying to to get too much power out of the electrical circuit in the house.
Soldering, component lead bending looks like a 5 year old could have done better.
Poor copy of Yamaha m50 m70
Rediculously over engineered. FAR more things to go wrong. Bad engineering. The designer was just showing off.