Hi AAK,
At the time Counterpoint switched to Sovtek 6922's, they were the most reliable tube available in quantity that didn't cost a fortune. They were lightyears ahead of the National 6DJ8's they were using. There just was not anything else available in quantity for their purpose.
The amount of distortion generated by a tube depends a great deal on the operating point. This will not be the same for all tubes of the same brand. You need to test a whole bunch of each.
Presently I like the Electroharmonix. These, by the way, are completely different tubes than the Sovtek. They are consistant too. Don't confuse the two.
JJ is supposed to be a very good tube. I have not tried them yet. It may be a while before I do. I am happy with the Electroharmonix.
-Chris 😉
At the time Counterpoint switched to Sovtek 6922's, they were the most reliable tube available in quantity that didn't cost a fortune. They were lightyears ahead of the National 6DJ8's they were using. There just was not anything else available in quantity for their purpose.
The amount of distortion generated by a tube depends a great deal on the operating point. This will not be the same for all tubes of the same brand. You need to test a whole bunch of each.
Presently I like the Electroharmonix. These, by the way, are completely different tubes than the Sovtek. They are consistant too. Don't confuse the two.
JJ is supposed to be a very good tube. I have not tried them yet. It may be a while before I do. I am happy with the Electroharmonix.
-Chris 😉
Max29 - Would you mind posting a picture of how you have mounted the transformer on cork please. I'd be interested in making this change to my unit.
Thanks
Stephen
Thanks
Stephen
Anatech - You mentioned in an earlier post that you needed the correct test equipment to be able to set the operating points of the tubes. Forgive me for asking what seems like a very obvious question: does this mean that it's a waste of time using (say) the flavour-of-the-month NOS tubes unless you can set the operating points correctly?
I'm wondering if I would be best buying the 6922EH (which I can buy here for about US$18 each) and then setting the trimmer pots to the middle of the relevant voltage range. I know this won't guarantee me the correct operating point (except by accident), but at least it will reduce the error of margin ...
Does this sound sensible?
Thanks
Stephen
I'm wondering if I would be best buying the 6922EH (which I can buy here for about US$18 each) and then setting the trimmer pots to the middle of the relevant voltage range. I know this won't guarantee me the correct operating point (except by accident), but at least it will reduce the error of margin ...
Does this sound sensible?
Thanks
Stephen
Hi Stephen,
There is absolutely no point in tube rolling without realigning in these units at all. Most people completely miss that point.
What I would suggest you do is buy some good brand that is not microphonic (that you can test, tap the tube and see how loud it rings).
To put some perspective on this. After aligning the unit with existing tubes, most comments are strongly positive - they gripe about having to pay for this to be done though! 😉 Hey, I didn't design the thing!
Comments on the 6922EH I have had range to "almost as good as "XXX" brand, to a solid preference for them. You can't please everyone, and I don't try with tube brand selection. No one has said they sound bad and everyone is pleased with the low noise.
Fad tubes (flavour of the month) are a waste of money. You do need to set each tube secton up. Unavoidable. Do not move the trim pots. Get to know a technician and buy him coffee! 😀
You need a low distortion audio generator and a THD meter. You may be able to do this with RMAA. Slower though. Watch your levels!
-Chris
There is absolutely no point in tube rolling without realigning in these units at all. Most people completely miss that point.
What I would suggest you do is buy some good brand that is not microphonic (that you can test, tap the tube and see how loud it rings).
To put some perspective on this. After aligning the unit with existing tubes, most comments are strongly positive - they gripe about having to pay for this to be done though! 😉 Hey, I didn't design the thing!
Comments on the 6922EH I have had range to "almost as good as "XXX" brand, to a solid preference for them. You can't please everyone, and I don't try with tube brand selection. No one has said they sound bad and everyone is pleased with the low noise.
Fad tubes (flavour of the month) are a waste of money. You do need to set each tube secton up. Unavoidable. Do not move the trim pots. Get to know a technician and buy him coffee! 😀
You need a low distortion audio generator and a THD meter. You may be able to do this with RMAA. Slower though. Watch your levels!
-Chris
Chris..anatech said:
The R51 is 105 K and maybe only 1/2 watt.
Can i replace as you said with a 75K 1watt ?
R59 -499R isa 1watt or ....
R61 - R53 -are all 1 Watt types or 2 watt or ....
Max
Hi Guys,
Sorry, my email notification is intermittent for threads. I hunted this one down again.
Max,
I figure around 160V across the resistor with 1.6mA of current will dissipate 0.256W, use a 1W. I think most of the other parts are 1/2W, but there is no parts list in my manual. Have a good look, the plate resistors were 2W. If you see a resistor that runs too hot, go up in power (unless it's a circuit fault of course).
Hi Arthur,
Like everyone else, I've suffered long in the business. 😉
-Chris
Sorry, my email notification is intermittent for threads. I hunted this one down again.
Max,
I figure around 160V across the resistor with 1.6mA of current will dissipate 0.256W, use a 1W. I think most of the other parts are 1/2W, but there is no parts list in my manual. Have a good look, the plate resistors were 2W. If you see a resistor that runs too hot, go up in power (unless it's a circuit fault of course).
Hi Arthur,
Like everyone else, I've suffered long in the business. 😉
-Chris
The frightening part is that Chris knows most of this stuff from memory. That means he's had his hands inside more than a few of them. Our personal Counterpoint Jesus.
Chris, oh Lord, My new 3.1 I just bought on Ebay has a bald spot. Can you cure it? 😀
Ok. Enough with the funnies. I bought a 3.0 on ebay, it has 3.1 stamped on the circuit board. It apparently works fine, except for a bit of noise/glitchyness. Easy enough to fix that stuff. No relay or mute in sight on the hardware side, so Presume no matter what the board says, it's a 3.0.
It's also got two radio shack knobs for the selectors instead of the stock counterpoint knobs (silver). Got any spares? No big deal overall, I got it for $170, which is far below 'percieved' market value.
I also bought a blown (one channel) Parasound 1500A from the same guy. More broken amps! I guess I felt naked without any broken (well, large piles, anyway) stuff lying about. When I get all those back, I'll have about 11-13 (I dunno) power amps. Oh wait, 16. I'm sure there are guys here with far more.
Chris, oh Lord, My new 3.1 I just bought on Ebay has a bald spot. Can you cure it? 😀
Ok. Enough with the funnies. I bought a 3.0 on ebay, it has 3.1 stamped on the circuit board. It apparently works fine, except for a bit of noise/glitchyness. Easy enough to fix that stuff. No relay or mute in sight on the hardware side, so Presume no matter what the board says, it's a 3.0.
It's also got two radio shack knobs for the selectors instead of the stock counterpoint knobs (silver). Got any spares? No big deal overall, I got it for $170, which is far below 'percieved' market value.
I also bought a blown (one channel) Parasound 1500A from the same guy. More broken amps! I guess I felt naked without any broken (well, large piles, anyway) stuff lying about. When I get all those back, I'll have about 11-13 (I dunno) power amps. Oh wait, 16. I'm sure there are guys here with far more.
Hi Ken,
Just sourcing the last wacky parts for your Adcom (driver board had serious issues), then the M-05. You will have your amps back. 😉
I sold all my Counterpoint knobs to a guy about a year ago. I'm sure M.E. has some more.
-Chris
Just sourcing the last wacky parts for your Adcom (driver board had serious issues), then the M-05. You will have your amps back. 😉
I sold all my Counterpoint knobs to a guy about a year ago. I'm sure M.E. has some more.
-Chris
The Parasound has a mono switch on the back.
The guy said he tried to hook his sub up to it and suddenly, one channel stopped working. He threw it aside for a few years and now he sells it on ebay.
I recieved the amp on Friday morning. I decided of course...to open it up and look at the insides.
hhmmm.... all fuses good. Very strange. BJT output, presumably..fuses blow. 96.75249% chance of that. Soooo. .......hey!!
uhmm..why don't I test that channel out. I was at work, but managed to find a set of speakers, and a rca cable.
That mono switch can give folks grief..
Sure enough, both channels work! Ok.
So the guy had it in mono and forgot to flip it back, or accidentally flipped it to mono while futzing around back there.
Got a mint Parasound 1500A for 1/4rd-1/3rd market value. Oops.
made my day! How are you guys doing?
The guy said he tried to hook his sub up to it and suddenly, one channel stopped working. He threw it aside for a few years and now he sells it on ebay.
I recieved the amp on Friday morning. I decided of course...to open it up and look at the insides.
hhmmm.... all fuses good. Very strange. BJT output, presumably..fuses blow. 96.75249% chance of that. Soooo. .......hey!!
uhmm..why don't I test that channel out. I was at work, but managed to find a set of speakers, and a rca cable.
That mono switch can give folks grief..
Sure enough, both channels work! Ok.
So the guy had it in mono and forgot to flip it back, or accidentally flipped it to mono while futzing around back there.
Got a mint Parasound 1500A for 1/4rd-1/3rd market value. Oops.
made my day! How are you guys doing?
Chris - You wouldn't happen to know the output impedance of the 5.1 would you? Many thanks
Stephen
Stephen
Hi Stephen,
Sorry, I don't know off hand. The owner's manual should list it. It was never really important.
The output comes off a paralleled plate (both sections of a 6DJ8) and through an 8 uF film type capacitor. Treat it as a high impedance output. I would be tempted to install smaller caps on the output. The service manual really didn't give us much in some of these early models.
You could measure the output impedance. Use an AC voltmeter and load the output until it drops to 1/2 it's original value. Your load resistance now is the same as the effective output impedance. That's faster than figuring it out from the schematic. More apt to be right as well.
-Chris
Sorry, I don't know off hand. The owner's manual should list it. It was never really important.
The output comes off a paralleled plate (both sections of a 6DJ8) and through an 8 uF film type capacitor. Treat it as a high impedance output. I would be tempted to install smaller caps on the output. The service manual really didn't give us much in some of these early models.
You could measure the output impedance. Use an AC voltmeter and load the output until it drops to 1/2 it's original value. Your load resistance now is the same as the effective output impedance. That's faster than figuring it out from the schematic. More apt to be right as well.
-Chris
Interesting thread. I have an SA-5.1 that I had started to do some Altavista type upgrades to, but was really just trying to work the noise out of it. I wish this thread had been around before I started to do that 🙄
The voltages as I recall look correct. I have pretty much replaced all the electrolytic caps (I used 100uf 500V Cerafines in the PSU, a couple of 220-220uf 350V Cerafines in the HV regulation stage, etc.). I do have the service manual/schematics.
Chris:
1) you mention that you like the 6922EH tubes for these... something like the steel-pin (or gold pin) EH tubes from Partsconnexion? I am uncertain as to how good the line/phono tubes I am using are, so I should probably put something new like this in to make sure what I am hearing isn't just noisy tubes (it is just a low level hiss/hum 2' from the tweeters with no music playing).
2) also, one of the first things mentioned in the service manual is to check the ground resistance from the ground side of C53 (IIRC) to the ground pin on the AC connector and verify that it is <0.5 ohms. I have had alot of problems where the ground connects between the main circuit board and chassis in getting this to be low enough (mine is usally more like ~1.2 ohms, even with 4-wire measurement). Since you hadn't mentioned it in this thread, I guess this probably isn't that important.
I don't have the equipment or access to it to do the bias adjustments, so I haven't touched that, but I am probably the 3-4th owner of this, and it came with the wrong tubes in the line stage (12AX7s or something like that) to begin with.
The voltages as I recall look correct. I have pretty much replaced all the electrolytic caps (I used 100uf 500V Cerafines in the PSU, a couple of 220-220uf 350V Cerafines in the HV regulation stage, etc.). I do have the service manual/schematics.
Chris:
1) you mention that you like the 6922EH tubes for these... something like the steel-pin (or gold pin) EH tubes from Partsconnexion? I am uncertain as to how good the line/phono tubes I am using are, so I should probably put something new like this in to make sure what I am hearing isn't just noisy tubes (it is just a low level hiss/hum 2' from the tweeters with no music playing).
2) also, one of the first things mentioned in the service manual is to check the ground resistance from the ground side of C53 (IIRC) to the ground pin on the AC connector and verify that it is <0.5 ohms. I have had alot of problems where the ground connects between the main circuit board and chassis in getting this to be low enough (mine is usally more like ~1.2 ohms, even with 4-wire measurement). Since you hadn't mentioned it in this thread, I guess this probably isn't that important.
I don't have the equipment or access to it to do the bias adjustments, so I haven't touched that, but I am probably the 3-4th owner of this, and it came with the wrong tubes in the line stage (12AX7s or something like that) to begin with.
Hi Pars,
Throwing parts at Michael's designs may make a difference, but will never fix the problems. He does make a living from this though.
Try the 6922EH, they are quiet in Counterpoint gear and they sound good. 12AX7EH for those if you need them (phono). The normal pins are just fine. If the socket is noisy, the contacts are loose or corroded, gold pins will not help you in any way.
If you do not have the equipment, it's good you didn't touch anything. Once you have most of your problems sorted, take it to a good tech and have them set the unit up.
The manual shows 6DJ8 / 6922, but some may have been modified for were early models that used 12AX7's. The best thing to do is measure the heater voltage in the socket. The heaters are in series for the 6 V heaters, parallel for the 12AX7 types.
-Chris
Throwing parts at Michael's designs may make a difference, but will never fix the problems. He does make a living from this though.
Try the 6922EH, they are quiet in Counterpoint gear and they sound good. 12AX7EH for those if you need them (phono). The normal pins are just fine. If the socket is noisy, the contacts are loose or corroded, gold pins will not help you in any way.
If you do not have the equipment, it's good you didn't touch anything. Once you have most of your problems sorted, take it to a good tech and have them set the unit up.
The manual shows 6DJ8 / 6922, but some may have been modified for were early models that used 12AX7's. The best thing to do is measure the heater voltage in the socket. The heaters are in series for the 6 V heaters, parallel for the 12AX7 types.
-Chris
Chris,
Thanks for the reply. Yes, the smilie was for my original misguided efforts to replicate what Mr. Elliot does using rather obscenely priced parts. As I have built a few headphone amps (up to a discrete Gilmore) and progressed in DIY'ing from that point, I have learned that architecture and design is more prevailing than throwing boutique parts at something.
One of the mods I already did was to replace all the original sockets with Azuma gold pin tube sockets, hence my question regarding gold vs. steel pins, as gold is only good for lack of oxidation. My other question is that Partsconnexion only shows std. 6922 designation under the Electroharmonix tube section... not 6922EH. Link here, click on Electroharmonix. I assume that these are one and the same, but I could be wrong? Do EH make more than one 6922?
As far as I know, and have talked to Mike Elliot about this, there were no SA5.1s put out with 12AX7s (or 12AY7s) can't remember what was in it. The person I bought the pre from mistakenly thought they were the same as 6DJ8s.
I'll try to find a good tech to set the unit up once I have worked the noise out of it (hopefully). Any recommendations on someone in Chicago?
Thanks again for the reply,
Chris
Thanks for the reply. Yes, the smilie was for my original misguided efforts to replicate what Mr. Elliot does using rather obscenely priced parts. As I have built a few headphone amps (up to a discrete Gilmore) and progressed in DIY'ing from that point, I have learned that architecture and design is more prevailing than throwing boutique parts at something.
One of the mods I already did was to replace all the original sockets with Azuma gold pin tube sockets, hence my question regarding gold vs. steel pins, as gold is only good for lack of oxidation. My other question is that Partsconnexion only shows std. 6922 designation under the Electroharmonix tube section... not 6922EH. Link here, click on Electroharmonix. I assume that these are one and the same, but I could be wrong? Do EH make more than one 6922?
As far as I know, and have talked to Mike Elliot about this, there were no SA5.1s put out with 12AX7s (or 12AY7s) can't remember what was in it. The person I bought the pre from mistakenly thought they were the same as 6DJ8s.
I'll try to find a good tech to set the unit up once I have worked the noise out of it (hopefully). Any recommendations on someone in Chicago?
Thanks again for the reply,
Chris
Hi Chris,
Well, my memory ain't perfect. The SA 5.0 is the same beasty in my mind. I just accept them as I see them since many get modified to hect. I'll check the heater connections to confirm the tube type, but I don't question much these days.
Those two 6922 tubes are the same. I believe they are also made with gold pins. They are available from New Sensor, that's where I buy them. The parts at Partsconnexion are the same. Don't buy stupidly matched tubes. You're further ahead to buy a bunch and sort them yourself. Actually, New Sensor is the distributor and they are in the USA. Buy them direct unless there is a compelling reason to do otherwise. I don't know how thick the gold plating is, you may end up with base metal in short order.
As far as a technician in Cicago, HEY YOU GUYS! pipe up! 😉
-Chris
Well, my memory ain't perfect. The SA 5.0 is the same beasty in my mind. I just accept them as I see them since many get modified to hect. I'll check the heater connections to confirm the tube type, but I don't question much these days.
Those two 6922 tubes are the same. I believe they are also made with gold pins. They are available from New Sensor, that's where I buy them. The parts at Partsconnexion are the same. Don't buy stupidly matched tubes. You're further ahead to buy a bunch and sort them yourself. Actually, New Sensor is the distributor and they are in the USA. Buy them direct unless there is a compelling reason to do otherwise. I don't know how thick the gold plating is, you may end up with base metal in short order.
As far as a technician in Cicago, HEY YOU GUYS! pipe up! 😉
-Chris
Chris,
Thanks again for the reply. I need some other parts so will probably get them from Partsconnexion. Would something like an HP339a be good enough for setting the bias? I have a scope and an HP bench meter, but no Audio Precision 1's laying around (or Soundtech 1701s, etc. 😱 ).
I also don't have a tube tester, and assume that is what you meant by "You're further ahead to buy a bunch and sort them yourself." Or did you mean by just trying them?
Thanks,
Chris
Thanks again for the reply. I need some other parts so will probably get them from Partsconnexion. Would something like an HP339a be good enough for setting the bias? I have a scope and an HP bench meter, but no Audio Precision 1's laying around (or Soundtech 1701s, etc. 😱 ).
I also don't have a tube tester, and assume that is what you meant by "You're further ahead to buy a bunch and sort them yourself." Or did you mean by just trying them?
Thanks,
Chris