The Class-G Amplifier
Hi Folks,
Here's my Complementary Vertical Mosfet Class-G amp....high efficiency in real music signals
Hope you like it.....
I am preparing the PCB's.... for my car amp.
All Tansistors are CB 2N5551/5401 & EF BC556/BC546
Mosfets IRFP540N/9540N
Opamp NE5532
Schottky's MBR160S
Rails are +- 30V, +-60V
Load is 8 ohms
power is 150Wrms
BW 150KHZ
Sine wave efficiency is around 80%
regards,
Kanwar
Shown here is conceptual schematic not actual one
Hi Folks,
Here's my Complementary Vertical Mosfet Class-G amp....high efficiency in real music signals
Hope you like it.....
I am preparing the PCB's.... for my car amp.
All Tansistors are CB 2N5551/5401 & EF BC556/BC546
Mosfets IRFP540N/9540N
Opamp NE5532
Schottky's MBR160S
Rails are +- 30V, +-60V
Load is 8 ohms
power is 150Wrms
BW 150KHZ
Sine wave efficiency is around 80%
regards,
Kanwar
Shown here is conceptual schematic not actual one
An externally hosted image should be here but it was not working when we last tested it.
Interesting the resistances values...hummmm...very good
Ahahahaha
You may love your car deeply... as the car may be able to see values...but we...humans...we do not deserve that?
I think you forgot the values Kanwar.
Nice tophologie...now new...but nice.
The switching supply may be special too.... industrial secret?
regards,
Carlos
Ahahahaha
You may love your car deeply... as the car may be able to see values...but we...humans...we do not deserve that?
I think you forgot the values Kanwar.
Nice tophologie...now new...but nice.
The switching supply may be special too.... industrial secret?
regards,
Carlos
I sent mail to him...he will provide values soon
I am not sure if will be published to whole forum...i hope so.
I already have the switching supply i was needing.
Kanwar use to be very kind with me...he never forgot to answer any mails i have send...we have enormous respect dedicated to one each other.
regards,
Carlos
I am not sure if will be published to whole forum...i hope so.
I already have the switching supply i was needing.
Kanwar use to be very kind with me...he never forgot to answer any mails i have send...we have enormous respect dedicated to one each other.
regards,
Carlos
djk said:
anatech said:
I found this thread via Google while trying to track down an M-1.5t service manual, and technical information on the earlier Carver amps related to rail switching noise. I appreciate the great information that's in this thread, and I'd like to thank everyone for their insightful posts.
Specifically, in light of the two previous posts that I've quoted, I'd like to ask how how the M-1.5t and M-1.0t compare to the later amps in terms of audible/scopeable rail switching noise. Some people say its audible in the M-1.5t, others say it isn't. I have never scoped my M-1.5t outputs to look for HF switching noise, though I do notice an "etching" quality to the highs as the amp starts to illuminate the middle to upper power LEDs (suggesting operation on the higher rails). I wasn't aware of the problem until I hooked up new speakers. Admittedly, Class G and H theory are weak areas for me -- my forte is building Class A and AB tube amps.
for reference, my M-1.5t is a 20 year old unmolested virgin. I'm the original owner and no hack technician has ever come near it, myself included.
Any comments would be appreciated.
Hi solderhead,
The M 1.0 was the first design that started to sound good. Somewhere in this early time they went from switched supplies (bang-bang type) to a tracking class "B" type. This greatly reduced the glitching on the output signal. The "t" designation was "Tube Transfer Function Modified" (Later TFM). Among other things there was a resistor and capacitor-resistor combination at the output. This also helped reduce the high frequency glitch noise.
The M 1.5t was a more powerful model but essentially the same circuit. I think they sounded close to each other. You can still see the glitches on the output. The largest improvement was tracking, class "B" supplies, but the top rail is still a "bang-bang" type. Definite glitches on the output with this.
If you own one of these, it needs servicing right now. Things that are needed are:
1. New filter caps for the first two (lowest) power supply tiers.
2. Resistor values checked and some small capacitors replaced on the power supply board, or motherboard.
3. Voltage adjust trimmer control cleaned or replaced. Supply voltage corrected.
4. Bias controls on each amplifier channel cleaned or replaced. The bias will not be correct most likely.
5. Any leaked electrolyte cleaned up.
6. Solder joints checked and redone if required. Remove old solder first.
Not really shocking for a 20 year old amplifier.
Now, the newer series of amplifiers got better as time went on. TFM-25/45 were better still. Finally, the Lightstar was developed. It was a departure from earlier amplifiers and sounded much better. Other excellent models were things like the TFM-75. Scary power but good sound.
-Chris
The M 1.0 was the first design that started to sound good. Somewhere in this early time they went from switched supplies (bang-bang type) to a tracking class "B" type. This greatly reduced the glitching on the output signal. The "t" designation was "Tube Transfer Function Modified" (Later TFM). Among other things there was a resistor and capacitor-resistor combination at the output. This also helped reduce the high frequency glitch noise.
The M 1.5t was a more powerful model but essentially the same circuit. I think they sounded close to each other. You can still see the glitches on the output. The largest improvement was tracking, class "B" supplies, but the top rail is still a "bang-bang" type. Definite glitches on the output with this.
If you own one of these, it needs servicing right now. Things that are needed are:
1. New filter caps for the first two (lowest) power supply tiers.
2. Resistor values checked and some small capacitors replaced on the power supply board, or motherboard.
3. Voltage adjust trimmer control cleaned or replaced. Supply voltage corrected.
4. Bias controls on each amplifier channel cleaned or replaced. The bias will not be correct most likely.
5. Any leaked electrolyte cleaned up.
6. Solder joints checked and redone if required. Remove old solder first.
Not really shocking for a 20 year old amplifier.
Now, the newer series of amplifiers got better as time went on. TFM-25/45 were better still. Finally, the Lightstar was developed. It was a departure from earlier amplifiers and sounded much better. Other excellent models were things like the TFM-75. Scary power but good sound.
-Chris
Thanks for your help.
Part of the problem with Carver's amplifier designations is that there's a lot of alphabet soup that went with the marketing hype. I'm looking at some old Carver ads from the 1980s and the meaning of the "t" designation changed over time:
For the M-1.5t, the "t" designates that its transfer function was modified to null against the Mark Levinson ML-2.
for the M-1.0t, the "t" designates the the transfer fuction was modified to null against the un-named Stereophile challenge amp, which turned out to be a Conrad Johnson #5.
For other amps, like the Silver 7t, the "t" designated a transfer function modification to null against the Carver Silver 7 tube amp... and we all know that according to Bob Carver that was the best sounding tube amp that anyone ever made!
Later on there were all of those TFM-prefix amps that were supposed to have "tubey" transfer functions, etc.
Part of what makes this so confusing is that the marketing people changed the meaning of the "t" designator whenever it suited them, so without reference material to look at, one might as well guess at what the "t" means when applied to any particular model.
Thanks for the service tips regarding my the M-1.5t. The amp appears to be working fine, but if I really need to, I'll open it up and take measurements. Before I tear into my M-1.5t, I'd like to find a copy of the service manual. (You wouldn't believe what I've been going through trying to find one.) Now that Sunfire has been sold and Carver has retired, the new Sunfire owners have downsized Sunfire, and Carver support has been totally dismantled. If anyone should have a Service Manual and TSBs for the M-1.5t, please contact me.
Thanks again for your help.
Part of the problem with Carver's amplifier designations is that there's a lot of alphabet soup that went with the marketing hype. I'm looking at some old Carver ads from the 1980s and the meaning of the "t" designation changed over time:
For the M-1.5t, the "t" designates that its transfer function was modified to null against the Mark Levinson ML-2.
for the M-1.0t, the "t" designates the the transfer fuction was modified to null against the un-named Stereophile challenge amp, which turned out to be a Conrad Johnson #5.
For other amps, like the Silver 7t, the "t" designated a transfer function modification to null against the Carver Silver 7 tube amp... and we all know that according to Bob Carver that was the best sounding tube amp that anyone ever made!
Later on there were all of those TFM-prefix amps that were supposed to have "tubey" transfer functions, etc.
Part of what makes this so confusing is that the marketing people changed the meaning of the "t" designator whenever it suited them, so without reference material to look at, one might as well guess at what the "t" means when applied to any particular model.
Thanks for the service tips regarding my the M-1.5t. The amp appears to be working fine, but if I really need to, I'll open it up and take measurements. Before I tear into my M-1.5t, I'd like to find a copy of the service manual. (You wouldn't believe what I've been going through trying to find one.) Now that Sunfire has been sold and Carver has retired, the new Sunfire owners have downsized Sunfire, and Carver support has been totally dismantled. If anyone should have a Service Manual and TSBs for the M-1.5t, please contact me.
Thanks again for your help.
anatech said:
Thanks, I have some questions about some of these points. I have not been able to obtain a copy of the official Carver docs, though I have put together some notes from various non-official sources and I'd like to verify them:
1. I am familiar with the problems of aging electrolytic caps. Does the amp need prophylactic re-capping, even if the original caps display normal leakage current and ESR? Are those the odd multiple unit caps that will need to have a substitution board crafted as a replacement?
2. Are you referring to shotgun replacement of all of the 'lytics in the PSU board just because of their age, or are there other types of caps that need attention?
3. Does that refer to Power supply trim on the front-to-back PCB, set to +/- 124VDC measured at the large filter caps on the right side?
4. 3.4mVDC measured across the emitters of the two center output transistors on each channel?
6. I have heard that cold joints are a problem with Carver amps, and that its necessary to retouch joints on all of the output transistors and the hot-glued caps on the channel PCBs. Are there other places that are usual points of failure?
Before opening up the amp, I'd really prefer to get my hands on the proper documentation. Thanks again.
Hi solderhead,
Well, the "t" designator still stood for tube of some kind. I honestly don't think there were very many changes except to the resistor and RC combination. They did play with current feedback for a bit there too. It has it's own potentiometer issues. There is a modification note out on that as well. I replaced it with a 1K00 resistor and padded the other channel for matching gain.
I'll see what I can find. I did sell my shop about 10 years ago. I was the Canadian factory warranty shop and did talk to the engineers directly. The last units I worked on were the Lightstars and TFM-75 units. I did some of the pro amps from the same era. All my service information remained with the new owners. I am trying to rebuild my library.
Carver service seemed to be at war with everyone and they are still at it. I have no use for them. They went to a privately owned entity near the end, therefore they were not affected directly with Carver's shut down.
-Chris
Well, the "t" designator still stood for tube of some kind. I honestly don't think there were very many changes except to the resistor and RC combination. They did play with current feedback for a bit there too. It has it's own potentiometer issues. There is a modification note out on that as well. I replaced it with a 1K00 resistor and padded the other channel for matching gain.
I'll see what I can find. I did sell my shop about 10 years ago. I was the Canadian factory warranty shop and did talk to the engineers directly. The last units I worked on were the Lightstars and TFM-75 units. I did some of the pro amps from the same era. All my service information remained with the new owners. I am trying to rebuild my library.
Carver service seemed to be at war with everyone and they are still at it. I have no use for them. They went to a privately owned entity near the end, therefore they were not affected directly with Carver's shut down.
-Chris
Hi solderhead,
1. They should be bad by now. If they aren't, they will be soon. They do require a PCB be made to properly replace the dual section originals. There was a factory board made for replacement. I have exactly one left. They have been available and not alternatively over time.
2. Many smaller value capacitors dried out or have been overheated. Just replace them. Do not fail to measure the value of many resistors that commonly do drift. They are sensing for voltage control and protection. Near the transformer area (of course!). Measure anything that appears to have run warm. Do not forget that there is high voltage across some of these. Odd things can happen.
3. Yes. I normally set it at 118 VDC. The adjustment tends to creep up over time.
4. Yes, exactly. With no signal and no load connected.
5. If you see any. Sometimes not visible but you can sure smell it if you touch it with your soldering iron.
6. Not so much the outputs, but it's possible. The card connectors and any components that run hot. Especially on the power supply board near the transformer. Look were it's the most difficult to get to. I'm serious. These can be a pain.
Also, there are no real bleeders in this amp. Discharge all capacitors with a resistor please.
-Chris
To keep it short:
1. They should be bad by now. If they aren't, they will be soon. They do require a PCB be made to properly replace the dual section originals. There was a factory board made for replacement. I have exactly one left. They have been available and not alternatively over time.
2. Many smaller value capacitors dried out or have been overheated. Just replace them. Do not fail to measure the value of many resistors that commonly do drift. They are sensing for voltage control and protection. Near the transformer area (of course!). Measure anything that appears to have run warm. Do not forget that there is high voltage across some of these. Odd things can happen.
3. Yes. I normally set it at 118 VDC. The adjustment tends to creep up over time.
4. Yes, exactly. With no signal and no load connected.
5. If you see any. Sometimes not visible but you can sure smell it if you touch it with your soldering iron.
6. Not so much the outputs, but it's possible. The card connectors and any components that run hot. Especially on the power supply board near the transformer. Look were it's the most difficult to get to.
I'm serious. These can be a pain.Also, there are no real bleeders in this amp. Discharge all capacitors with a resistor please.
-Chris
Hi solderhead,
My pleasure.
I use liquid solder flux and add solder before I try to remove it once it gets bumpy and grey. More flux and add a little solder and that should do it. There are times when you may have to scrape the oxide off the leads before resoldering. Rinse all the flux off with Electrowash and a toothbrush or Lacquer Thinner and a toothbrush.
-Chris
My pleasure.
I use liquid solder flux and add solder before I try to remove it once it gets bumpy and grey. More flux and add a little solder and that should do it. There are times when you may have to scrape the oxide off the leads before resoldering. Rinse all the flux off with Electrowash and a toothbrush or Lacquer Thinner and a toothbrush.
-Chris
djk said:
If I understand this thing correctly, the rail switch on the MA/VZ amps don't switch in and out on a cycle-by-cycle basis the way all the rest of them do. It just switches infrequently between series and parallel power supply modes - in some way tied to junction temperature in the outputs. Solves any switching noise problem because for the most part it's class AB.
However, it seems like using one rail switch instead of four for a big-@** amp would be a great savings in complexity for woofer-specific applications. Any ideas as to whether the whole rail voltage can be switched QSC-style on a big grounded bridge? That is, without running into oscillation problems... It would probably need to keep the slew rates reasonable (there goes 20k), but I'm wondering if it might be worth throwing a prototype together.
wg_ski said:
Exactly, using grounded bridge one can save expensive switching components cost just because of monorail switching is required.
In crown the supplies just switches from parallel to series
In qsc pl9.0 the monorail is switched in 4 steps....
I had made both class-H 3 step monorail using n-channel mosfets, Class-G 2step monorail again using mosfets and another prototype of class-td for sub thats too in monorail design.....
Workhorse said:
Actually, I was thinking more in terms of saving PCB space. The 3-rail more or less conventional class H I'm working on now was a nightmare to get onto a 14 inch board (the limit for inexpensive prototypes). I should be ordering those right after I get done with Christmas expenses. And now I'm thinking about how best to use a bunch of Signal 80-25's for something even bigger. A pair of those in series should be ok to bridge into 2 ohms, provide plenty of rail taps, and get in the 5kW ballpark.
djk said:
That's what my calculations came out to. Even with 30% rail voltage sag. And it should be enough transformer to be able to pass the old 1/3 power FTC test. Nothing you can buy nowadays can do that. What I'm still wrestling with is fitting everything onto 14" boards and stuffing it all into 4U.
Why?
1. Because I can, and because I'm crazy, why else?
2.They would be used for powering labhorns (two per amp) when used outdoors. The amps I use now run 6dB into clip to get the desired SPL.
3. I have 8 of the transformers (cost me $30 each). That will power a whole stack.