I went and bought two Counterpoint SA-220 amplifiers. I decided to get two, so I could go stacked for biamp or separate mono-blocks. I am getting the schematic in a week or so, and am wondering if anyone here has ever taken a shot at modifying or upgrading the circuits in these units.
For those that are unfamiliar with the unit, it is a SS-fet based 220WPC output stage, coupled to a input buffer-predriver 6DJ8 based tube stage, that has even got a tube rectifier in it's PS!. It is very much like a tube pre-amp built right into a dual mono (single transformer, dual wound with separate caps and bridge rectification) Fet power amp. The unit weights 69lbs, and is internally strappable to a 600watt monoblock. According to what the manual says, you can upgrade the internal rail fuses to 20 amp, if you should desire to.. for low impedance loads like say.. A pair of Apogee Duettas, or the like. It runs typically blazingly-toaster hot like most fet amps.
Of course, the moment I read that the rail fuses can be upgraded to 20 amp... I spun off to Rat Shack in a cloud of hen $hit and small rocks.... and in they went!
I have to modify and tube-roll both units identically for monoblock/stereo use.
Any ideas?
For those that are unfamiliar with the unit, it is a SS-fet based 220WPC output stage, coupled to a input buffer-predriver 6DJ8 based tube stage, that has even got a tube rectifier in it's PS!. It is very much like a tube pre-amp built right into a dual mono (single transformer, dual wound with separate caps and bridge rectification) Fet power amp. The unit weights 69lbs, and is internally strappable to a 600watt monoblock. According to what the manual says, you can upgrade the internal rail fuses to 20 amp, if you should desire to.. for low impedance loads like say.. A pair of Apogee Duettas, or the like. It runs typically blazingly-toaster hot like most fet amps.
Of course, the moment I read that the rail fuses can be upgraded to 20 amp... I spun off to Rat Shack in a cloud of hen $hit and small rocks.... and in they went!
I have to modify and tube-roll both units identically for monoblock/stereo use.
Any ideas?
hmm. Ok. Not much action on this one! I accidentally ended up with a third. Don't ask how. 🙂 Well, OK. I fixed one of the original two, only after I bid on a third on ebay..because I was PO'd that the fix of my second unit was not advancing at a resonable rate..
I bid high..and now 20 minutes after I bid.. I fixed the second unit. Murphy's law! It looks like I'm going to win that one, so I'll end up with three.
Anyone got a schematic for this puppy at all?
Should I hand them out, like shop class, so we each have one to work on?
I bid high..and now 20 minutes after I bid.. I fixed the second unit. Murphy's law! It looks like I'm going to win that one, so I'll end up with three.
Anyone got a schematic for this puppy at all?
Should I hand them out, like shop class, so we each have one to work on?
Hi KBK,
I just fixed one. I will be working on modifications to make them sound good and be more reliable.
One thing you should know. Those outputs are really matched very tightly, to select a set you may have to buy 50 to get a set that is tight enough. It's not fun. That's why M.E. charges so much for a repair.
You should see where the SA-100 has got to so far. Mind you, it isn't the same circuit anymore. It has the sound people liked, only better.
For tubes, I have had great luck with the Electroharmonix 6922. I would recommend them highly. You will have to mess around with them to get the gains matched between channels.
One last warning, these units don't always match the schematic. Sometimes they don't even come close. You are further ahead to trace it out. Don't worry about the analog computer, it's jumpered at the factory at the minimum sensitivity. As close to off as it gets. I would put the lower rated fuses in if I were you.
-Chris
I just fixed one. I will be working on modifications to make them sound good and be more reliable.
One thing you should know. Those outputs are really matched very tightly, to select a set you may have to buy 50 to get a set that is tight enough. It's not fun. That's why M.E. charges so much for a repair.
You should see where the SA-100 has got to so far. Mind you, it isn't the same circuit anymore. It has the sound people liked, only better.
For tubes, I have had great luck with the Electroharmonix 6922. I would recommend them highly. You will have to mess around with them to get the gains matched between channels.
One last warning, these units don't always match the schematic. Sometimes they don't even come close. You are further ahead to trace it out. Don't worry about the analog computer, it's jumpered at the factory at the minimum sensitivity. As close to off as it gets. I would put the lower rated fuses in if I were you.
-Chris
I was kidding about the fuses, I have 10 amp ones in there right now.
There's these 6 499k resistors in between the Wima caps in the tubed power supply for the 6DJ8 predrivers. One of them was burnt out. I replaced it with something close..and the issue is still there. it seems these resistors need to be exact, or sumpthin'.
Anyway.. I manged to pop the adjacent one during a live voltage test..my dang meter was set to resitance! FUG!
Now both channels are distorted. FUGGIN HECK! Me? I'm short on time these days to 'duke it out' with gear like I used to. Hopefully, If I get some 1 watt 499k resistors, that will fix it. It seems these puppies in some way 'balance' the voltage that goes to the tubes. (B+?, now very low?) I've no idea what the bloody resistors do, and I don't have the energy at this time to take it fully apart and duke it out. Buying the third was the easy way out. Change the silver faeplate to my black one, (to have a black pair) and be done with it. Flip to mono, and leave them alone. Yeah right. That might last a day or two.
The screwy part, is I used 5 100k 1% 1/4 watt resistors to try to hit the 500K the others measured. No go. damn.... I gots to get the schematic..
This amp is also a ba$tard to work on, with the wiring and chassis, etc. Tubes and solid state. A perfect recipie for minor bouts of shocking behaviour. Can you say 'electrocution'? and Screwdrivers stuck in the ceiling? From the reaction of the muscles in the arm....
You see, I lent out the perfect, all original minty one I had first bought. I'm getting it back tomorrow so I can finally do comparative tests. And hopefully get the dead one working..while I await the arrival of the third. Eventually I'll have three working units. By then, i'll likely be out of time to do this sort of thing altogether..but also be in the quandry of having no manufactuer I know of.. make gear to my personal standard of sound quality.
I'm sure most of us here are familiar with that particular sitaution.
In the end, I expect I might get the completed boards for at leat two of them from Alta Vista....and then.. mod from there. I can also then sell the working components. Complete board/trans assembiles. It would drop the price of the upgrade to less than $1k US, each. Each channel board, matched and working/tuned should fetch about $150US, easy, on ebay. A drop in fix, and worth every bloody cent. Then, the main board assembly, in good clean shape, another $150, for sure. The upgrade is $1400, so, deduct about $450-550US from the price...
There's these 6 499k resistors in between the Wima caps in the tubed power supply for the 6DJ8 predrivers. One of them was burnt out. I replaced it with something close..and the issue is still there. it seems these resistors need to be exact, or sumpthin'.
Anyway.. I manged to pop the adjacent one during a live voltage test..my dang meter was set to resitance! FUG!
Now both channels are distorted. FUGGIN HECK! Me? I'm short on time these days to 'duke it out' with gear like I used to. Hopefully, If I get some 1 watt 499k resistors, that will fix it. It seems these puppies in some way 'balance' the voltage that goes to the tubes. (B+?, now very low?) I've no idea what the bloody resistors do, and I don't have the energy at this time to take it fully apart and duke it out. Buying the third was the easy way out. Change the silver faeplate to my black one, (to have a black pair) and be done with it. Flip to mono, and leave them alone. Yeah right. That might last a day or two.
The screwy part, is I used 5 100k 1% 1/4 watt resistors to try to hit the 500K the others measured. No go. damn.... I gots to get the schematic..
This amp is also a ba$tard to work on, with the wiring and chassis, etc. Tubes and solid state. A perfect recipie for minor bouts of shocking behaviour. Can you say 'electrocution'? and Screwdrivers stuck in the ceiling? From the reaction of the muscles in the arm....
You see, I lent out the perfect, all original minty one I had first bought. I'm getting it back tomorrow so I can finally do comparative tests. And hopefully get the dead one working..while I await the arrival of the third. Eventually I'll have three working units. By then, i'll likely be out of time to do this sort of thing altogether..but also be in the quandry of having no manufactuer I know of.. make gear to my personal standard of sound quality.
I'm sure most of us here are familiar with that particular sitaution.
In the end, I expect I might get the completed boards for at leat two of them from Alta Vista....and then.. mod from there. I can also then sell the working components. Complete board/trans assembiles. It would drop the price of the upgrade to less than $1k US, each. Each channel board, matched and working/tuned should fetch about $150US, easy, on ebay. A drop in fix, and worth every bloody cent. Then, the main board assembly, in good clean shape, another $150, for sure. The upgrade is $1400, so, deduct about $450-550US from the price...
KBK said:
Try to search the web. Due Counterpoint is finished few years before, the founder of the company still keep a new homepage with modification kits, and general help for his amps.
I don't remeber the location, but I saw it, few months before.
sajti
Hi KBK,
I was a warranty service center for Counterpoint up until the end. They still owed me $$$.
Oh well.
I would think twice about upgrading those amps. I call it the Michael merry go round. Fad central.
Those resistors do not have to be precision parts. Can you say, plate supply decoupling resistor? I think you are looking for 499 ohm parts. 470 to 510 ohm values should work fine. The plate resistor should be 100K ohms.
-Chris
I was a warranty service center for Counterpoint up until the end. They still owed me $$$.
Oh well.I would think twice about upgrading those amps. I call it the Michael merry go round. Fad central.
Those resistors do not have to be precision parts. Can you say, plate supply decoupling resistor? I think you are looking for 499 ohm parts. 470 to 510 ohm values should work fine. The plate resistor should be 100K ohms.
-Chris
Got a schematic? I'll pay you Alta Vista's price. That'll bring a few bucks in. I'm sure Michael won't mind.
That's $75US, plus $14US shippng and handling. That's $89US. Then, dollar conversion (approx 1.21)makes it.....about $110.00 cdn.
That's $75US, plus $14US shippng and handling. That's $89US. Then, dollar conversion (approx 1.21)makes it.....about $110.00 cdn.
Hi KBK,
I don't have an emailable copy. And yeah, Michael would freak. The "manuals" are broken up into insanely small sections. Something that would be 6 pages is a book with Counterpoint. I will help you out. The circuits are very simple. As I said before, they may not match the printed version.
Counterpoint makes many design errors, these are created anew in some "upgrades". Please use your common sense when dealing with upgrades and general information.
The reason I have redesigned the SA-100 (slaughters the SA-220 now and I'm not done yet) is that some Counterpoint customers tracked me down. (I sold my shop 7 - 8 years ago and moved to a different city!) They needed a good tech to deal with their product. Now that I had time to spend I looked more closely at the circuits and saw the design faults. Understand that you can't modify a product while being warranty for same, so I didn't bother studying them at the time. SO after fixing the power supply and tube circuits, it's time to convert the output stage to bipolar. I am building a prototype of that now. Other things on the "fix" list are the DA-10 (after Michael mod), SA-220, SA-1000, SA-2000 / 3000.
I don't have a problem with Michael, just these products and the mods that follow.
-Chris
I don't have an emailable copy. And yeah, Michael would freak. The "manuals" are broken up into insanely small sections. Something that would be 6 pages is a book with Counterpoint. I will help you out. The circuits are very simple. As I said before, they may not match the printed version.
Counterpoint makes many design errors, these are created anew in some "upgrades". Please use your common sense when dealing with upgrades and general information.
The reason I have redesigned the SA-100 (slaughters the SA-220 now and I'm not done yet) is that some Counterpoint customers tracked me down. (I sold my shop 7 - 8 years ago and moved to a different city!) They needed a good tech to deal with their product. Now that I had time to spend I looked more closely at the circuits and saw the design faults. Understand that you can't modify a product while being warranty for same, so I didn't bother studying them at the time. SO after fixing the power supply and tube circuits, it's time to convert the output stage to bipolar. I am building a prototype of that now. Other things on the "fix" list are the DA-10 (after Michael mod), SA-220, SA-1000, SA-2000 / 3000.
I don't have a problem with Michael, just these products and the mods that follow.
-Chris
I'm not an EE, but I do know parts selection like the back'o'me hand. I do also know grounding, noise isolation and parts location, tracing, etc on boards for minimal interference and issues. This, of course, allows one to second guess many engineers, and create something that sounds better than their work. As they say, anyone can make something great if price is no object. And anyone can improve on any other's design work. The principle reason they tend to have computer programming 'teams', not individuals. But we both know all that, it seems.
More than anything, I'm looking at this point to do a basic parts upgrade. then, see what comes out of that effort. I need the schematic to do this properly, of course. I've always gone through the effort to do modification and repair work blind.. with no supporting schematic. This I figured was the best training ground of all. Fix that puppy with your *** blown off! Anything after that should be ridiculously simple, meaning..using a schematic, for once.
So the one is broken. Micheal was kind enough to tell me the fix I needed for the SA-220, in a few seconds. I took five secs to tell him the issue, he took five secs to tell me the fix. He stated basically what you did, but stated the caps were bad as well. I've never seen the traces (if there are any) on the underside of the main board, and can't see where anything goes due to the size of the caps, etc. A shematic is the way to go. Notice the repeat on my harping of the need for the schematic? 🙂
Yes, I do see you hinting at the mod stuff. But I need working amplifiers at this time. I've got others, but I'm kinda (currently) in love with the idea of the SA220/220 mono set. I always wanted them. At least until I've had them for a while. Do you need a few to work on to do the design work? I love the sound, but not the lack of extreme grunt at the bottom. My 300kuf Belles 450 does that pretty well. I go to the TO area fairly often. Where in Ontario?
I'm Itching to do that fix tonight, but I'm SUPPOSED to be working on modding the optics package for a JVC G1100 DILA for a friend......
Edit: DOH!! 500ohms. fug.
More than anything, I'm looking at this point to do a basic parts upgrade. then, see what comes out of that effort. I need the schematic to do this properly, of course. I've always gone through the effort to do modification and repair work blind.. with no supporting schematic. This I figured was the best training ground of all. Fix that puppy with your *** blown off! Anything after that should be ridiculously simple, meaning..using a schematic, for once.
So the one is broken. Micheal was kind enough to tell me the fix I needed for the SA-220, in a few seconds. I took five secs to tell him the issue, he took five secs to tell me the fix. He stated basically what you did, but stated the caps were bad as well. I've never seen the traces (if there are any) on the underside of the main board, and can't see where anything goes due to the size of the caps, etc. A shematic is the way to go. Notice the repeat on my harping of the need for the schematic? 🙂
Yes, I do see you hinting at the mod stuff. But I need working amplifiers at this time. I've got others, but I'm kinda (currently) in love with the idea of the SA220/220 mono set. I always wanted them. At least until I've had them for a while. Do you need a few to work on to do the design work? I love the sound, but not the lack of extreme grunt at the bottom. My 300kuf Belles 450 does that pretty well. I go to the TO area fairly often. Where in Ontario?
I'm Itching to do that fix tonight, but I'm SUPPOSED to be working on modding the optics package for a JVC G1100 DILA for a friend......
Edit: DOH!! 500ohms. fug.
Hi KBK
I think that the schematic of the SA 220 is very similar to the SA 100.
The SA 100 schematic is here (clic in , Further projects) at
http://www.pi.infn.it/~federico/unofficial.htm
Hope it help.
I think that the schematic of the SA 220 is very similar to the SA 100.
The SA 100 schematic is here (clic in , Further projects) at
http://www.pi.infn.it/~federico/unofficial.htm
Hope it help.
Hi KBK,
The supply section of the SA-220 is completely different to the SA-220. This is where your problem is. If you look to the left, you will see I'm in Georgetown, On. E mail me if you need help. I have a photo of the 220, but I think it's topside only.
Yes, I have hinted at mods. These are basic circuit changes that anyone should be able to see are lacking if they do any design work. I am not trying to "snipe" at Michael's designs. I have repaired a few basic, real faults in the SA-100 (design wise). I have gone further and changed the design completely as well. This is a progression (not Natural 😀 ).
-Chris
The supply section of the SA-220 is completely different to the SA-220. This is where your problem is. If you look to the left, you will see I'm in Georgetown, On. E mail me if you need help. I have a photo of the 220, but I think it's topside only.
Yes, I have hinted at mods. These are basic circuit changes that anyone should be able to see are lacking if they do any design work. I am not trying to "snipe" at Michael's designs. I have repaired a few basic, real faults in the SA-100 (design wise). I have gone further and changed the design completely as well. This is a progression (not Natural 😀 ).
-Chris
Anyone with experience with the NPMs
I see that there is a counterpoint expert in this thread.
May I ask if there is any opinion / experience with the Natural Progression Monos?
How are they compared to the NPS series and the modified SA220s?
Thanks.
I see that there is a counterpoint expert in this thread.
May I ask if there is any opinion / experience with the Natural Progression Monos?
How are they compared to the NPS series and the modified SA220s?
Thanks.
Hi phi70,
I am not a fan of the NPS series, or the newer product. Michael has yet to learn how to build a power supply. His errors got worse with newer product. The NPS series has a circuit fault in the bias circuit. He actually made a constant temperature circuit rather than a bias control circuit.
For me, I find I can modify an SA-100 and get far better sound quality (not done yet), the SA-220 is only larger so those changes will need to be scaled up somewhat, but they are the same.
I find that some newer models still suffer similar faults as the older ones in some regards, but at least they don't explode as often.
I've ignored his later mods as they tend to center on using his newer circuits so he can use bipolar outputs.
-Chris
I am not a fan of the NPS series, or the newer product. Michael has yet to learn how to build a power supply. His errors got worse with newer product. The NPS series has a circuit fault in the bias circuit. He actually made a constant temperature circuit rather than a bias control circuit.
For me, I find I can modify an SA-100 and get far better sound quality (not done yet), the SA-220 is only larger so those changes will need to be scaled up somewhat, but they are the same.
I find that some newer models still suffer similar faults as the older ones in some regards, but at least they don't explode as often.
I've ignored his later mods as they tend to center on using his newer circuits so he can use bipolar outputs.
-Chris
Ok. I've got a odd situation with SA-220's again. A quick one for Chris. Once again, I've got three of these. Love those hybrids. I still have the same two, and a cranky and beat up SA-20 came my way for virtually nothing. Gonna sell the two good looking units..and keep the junker.
Swapped tubes across channels, and swapped relays.
The channel not operating is a HAIR warmer during warm up, and a hair warmer at full stability (20 min). It puts out a mild 'buzz', sonically, no DC offset-this buzz, after the relay connects. volume cranked on pre-amp, and a tiny high frequency version of the signal comes through. that's it. Last quickie I haven't done, is to try cleaning the mono switch on that side. And those schematics are a bugger. Not a cleanly drawn circuit amongst them.
Any clues?
Oh yeah, the M-05. What do you think of the idea of fxing it and then blowing it out on Ebay? That's one way to get around this current issue.
Swapped tubes across channels, and swapped relays.
The channel not operating is a HAIR warmer during warm up, and a hair warmer at full stability (20 min). It puts out a mild 'buzz', sonically, no DC offset-this buzz, after the relay connects. volume cranked on pre-amp, and a tiny high frequency version of the signal comes through. that's it. Last quickie I haven't done, is to try cleaning the mono switch on that side. And those schematics are a bugger. Not a cleanly drawn circuit amongst them.
Any clues?
Oh yeah, the M-05. What do you think of the idea of fxing it and then blowing it out on Ebay? That's one way to get around this current issue.
Hi Ken,
Interesting fault. I would think you would have a DC offset condition or low bias current. The low, tinny audio suggests an open contact. Swing it by if you want.
I am trying to get back into the M-05. I had a shot (cortisone) in the left shoulder and am expecting one in the right. That should put me near the end of January where I can manipulate this beastie. I am also going to try and give you back the dual AC cords our previous tech combined into one.
How cheap did you get the SA-20? I need a prototype chassis and the tube section output is inferior to the SA-220 (not the same amp really). He paralleled the last tube for the SA-20 and runs the SA-220 as a pseudo constant current loaded animal. So it will have much higher distortion than an SA-220.
Take care Ken, Merry Christmas & Happy Holidays !!!
-Chris
Interesting fault. I would think you would have a DC offset condition or low bias current. The low, tinny audio suggests an open contact. Swing it by if you want.
I am trying to get back into the M-05. I had a shot (cortisone) in the left shoulder and am expecting one in the right. That should put me near the end of January where I can manipulate this beastie. I am also going to try and give you back the dual AC cords our previous tech combined into one.
How cheap did you get the SA-20? I need a prototype chassis and the tube section output is inferior to the SA-220 (not the same amp really). He paralleled the last tube for the SA-20 and runs the SA-220 as a pseudo constant current loaded animal. So it will have much higher distortion than an SA-220.
Take care Ken, Merry Christmas & Happy Holidays !!!
-Chris
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