Hi Chris,
Thank You again for the info. I will put a better heatsink on the 2N3440, found some better and bigger heatsinks for that TO-39 package. I always thought the one the 2N3440 had was too small. While I'm at it, I will add a nice heatsink to the LM350K since mine doesn't even have one.
I did already order the NTE MJE340 and and good snap on heatsinks. Good to have extra just in case 2N3440 dies for some reason.
Steve
Thank You again for the info. I will put a better heatsink on the 2N3440, found some better and bigger heatsinks for that TO-39 package. I always thought the one the 2N3440 had was too small. While I'm at it, I will add a nice heatsink to the LM350K since mine doesn't even have one.
I did already order the NTE MJE340 and and good snap on heatsinks. Good to have extra just in case 2N3440 dies for some reason.
Steve
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Still hum on one channel? Were the coupling caps in the line stage replaced? (The ones behind the 6DJ8?). I had one of these quite a few years ago that I did a few upgrades to, especially replacing the $3 volume pot that was originally used. I replaced the coupling caps, and there was a light hum in one channel. Drove me nuts, then I noticed the hum got worse as I moved my hand towards one of the coupling caps, kind of like a lightsaber sound effect. I turned the cap around, and problem solved. The quiet channel apparently had the outside 'foil" on the cap connected to the output of the tube, which shielded the input to the source follower, while the humming channel had the outside foil attached to the input of the source follower, acting as an antenna for induced hum. That's when I learned that non-polarized caps can still be directional.
Hi BrassTeacher,
Yes, absolutely! We learned that early in our general electronics training. If you use components larger than the originals you are begging for trouble. "Audiophile" parts are often unnecessarily large (and over-priced). Never mind that some even are worse than the originals. By the way, the original coupling capacitors used in those were fine, you didn't upgrade anything. Just saying.
The biggest issue with the less expensive volume controls is low level tracking. The gain of the preamp is also too high, making it a real problem.
Yes, absolutely! We learned that early in our general electronics training. If you use components larger than the originals you are begging for trouble. "Audiophile" parts are often unnecessarily large (and over-priced). Never mind that some even are worse than the originals. By the way, the original coupling capacitors used in those were fine, you didn't upgrade anything. Just saying.
The biggest issue with the less expensive volume controls is low level tracking. The gain of the preamp is also too high, making it a real problem.
Yes, I replaced the coupling caps with Auricap capacitors. I also replaced the Volume control and Balance control with TKD, way better than the originals. I did the same upgrades as what Alta Vista Audio was doing. I used the preamp for about a year with no humming issue, the humming started when I went with the Plitron transformer and a few other "upgrades" for the SA-1000. Before that with the original Counterpoint power transformer there was no hum of any kind. The hum only happened on the Phono side.
When I replaced the Power Transformer I also upgraded the 47uf electrolytic capacitor and some other tweaks for the preamp. If I remember correctly, it was about 4-5 changes so I didn't know which one may have caused it. I did find out later years down the road one of the issues was the 4 pair braid Phono cable I made and was using. But I never liked the Plitron PT inside the SA-1000. I have found a chassis I bought years ago for the PT and am going to remove the PT to outside of the SA-1000
About the caps being in the correct direction, I saw a video years ago about that outside foil and direction for shielding outside noises. The caps are in the correct direction.
I'm gonna start working on the SA-1000 next week, I have plenty of time now to work on my projects before getting back to work.
I replaced them with a pair that I hand-matched to 0.5%. I believe in matching parts from one channel to the next. So does KEF, and quite a few other companies. Just saying.
Oh, and it was a pair of Jantzen caps that were $3.00 each. Hardly an insane "boutique cap" purchase
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Well, they are coupling capacitors and therefore do not require matching at all. Speaker capacitors are part of a filter, and therefore it's "better" they are matched. However, variations in speaker drivers affect things much more. I designed speaker systems for the first decade of my career among other things.
About audio coupling capacitors. The dielectric is far more critical. Pure anything as a conductor matters not! Sorry, it's really true. It also flies directly in the face of what people who make audio capacitors tell you. I wonder why? Magnetic leads? They do not matter either. Current levels are too low, and when current levels are high enough it is a low impedance circuit - so it doesn't matter. Foil? Only for high current applications. Foil is actually more difficult to get an even tension wind and may be more microphonic in high gain circuits. Film is much better in this application.
The original capacitors used were fine, you can't get better to be honest. I use really good industrial capacitors. Guess what? Most audio caps are industrial ones relabelled (those are the best). Special audio types typically are worse. Tested and confirmed over many decades.
Audio beliefs are like a religion, so I expect pushback on this. However, what I have said is tested, proved reality. Confirmed by many others who do not make a profit on these components. ie, no vested interest.
-Chris
About audio coupling capacitors. The dielectric is far more critical. Pure anything as a conductor matters not! Sorry, it's really true. It also flies directly in the face of what people who make audio capacitors tell you. I wonder why? Magnetic leads? They do not matter either. Current levels are too low, and when current levels are high enough it is a low impedance circuit - so it doesn't matter. Foil? Only for high current applications. Foil is actually more difficult to get an even tension wind and may be more microphonic in high gain circuits. Film is much better in this application.
The original capacitors used were fine, you can't get better to be honest. I use really good industrial capacitors. Guess what? Most audio caps are industrial ones relabelled (those are the best). Special audio types typically are worse. Tested and confirmed over many decades.
Audio beliefs are like a religion, so I expect pushback on this. However, what I have said is tested, proved reality. Confirmed by many others who do not make a profit on these components. ie, no vested interest.
-Chris
So you're saying roll off on a signal from one channel to another doesn't matter. I'm still going to match one channel to the other, caps, resistors, inductors, transistors, and/or triodes. I've heard a noticeable difference in clarity and volume balance between channels, and the timbres matched better.
Oh, KEF reference series speakers computer-matched the drivers as well.
Did I claim any of the above? Please do not speak to me as if I am a child. I'm rebuilding a bunch to tube amps right now, and I'm using Vishay metallized polypropylene caps designed for industrial use. Tight tolerances, small in size, sound as good as the crazy expensive caps, if not better. The only foil caps I've ever used are styrene, and then as timing capacitors for voltage controlled oscillators, or when a voltage controlled filter needs a good, small-value cap
See above
Pushback? I was simply informing you that I had a good reason for swapping those caps out. Doesn't matter? Then why bother matching both sides of a 6DJ8 (or similar) in such an application as the gain stage of the SA-1000?
I make a living using my ears. I am also a natural skeptic. I test things I am told about, especially when it comes to audio and acoustic musical instruments, to separate the BS from the things that make a difference. I.e., you tell me something's better? I'll find out for myself, and have other people listen as a verification of what I'm hearing or if I'm imagining things. Example: differences in volume potentiometers. I built a prototype of my preamp design, and had myself, and my wife (a trained professional flutist), and the best audio tech in the Southeastern US (If you don't know Benny Amina, he's a genius) listen as I swapped out different volume pots using clip leads. Tested were a $3 ALPS, an ALPS RK27, and ALPS RK40, a Noble AP25, and a TKD CP2500. Yes, all were the same impedance.I gave no input, but listened to their observations. They both picked the TKD (The Noble was 2nd place, but you can't get them anymore).
Another example: While working in Benny's shop, a client brought in a Counterpoint SA-5000 with one phono channel out. After I found out there the signal stopped with the scope, which was the inout JFET, I replaced it and it was fine. The client had also gone to Mr. Elliot's "upgrade page and decided he wanted all the film caps replaced with the most expensive caps Percy Audio carried. When I asked Benny to verify with the owner, since what was in there from the factory was fine, the owner insisted. I told Benny it didn't make any sense to do it. So, Benny told me to write up an estimate based on what the owner wanted and he would present it before buying the parts. The owner decided at that point that existing caps were just fine.
I once met a guy that swore up and down that a piece of plain copper wire passed a signal in one direction better than another. He even said that the wire "remembers" which way the signal goes through it the first time, so you had to mark it so that you wouldn't install it backwards. Good thing I learned to keep a straight face.
I don't preach, or believe, audiophile BS, unless I can hear a difference that is noticeable enough to not be "wishful thinking" Interconnect cables that cost the equivalent of $200 a foot? I'm not even going to listen to them. Pure silver wire is cheaper than that, it's it's the most lossless conductor. Interconnects that are shielded on one end? You betcha I'll try them out. The biggest difference in cables? The ability of the connector to maintain a firm, positive contact. Are they made to where the inductance and capacitance nearly cancel each other out? I've heard the difference, and yes, it's worth it, within reason. There's a reason we twist the wires on tube filament supplies that are AC.
So, if you're trying to convince me about paying stupid money for stuff that doesn't make a difference, that ship sailed a long time ago
Hi,
I redesigned the power supplies on Counterpoint reamps to be reliable and have higher performance, I was authorized warranty. The official upgrades were nonsense and a money grab as far as I'm concerned. Anyway, I know this product inside out, backwards and upside down. Debate if you want. But you are talking to someone who actually knows this industry dead cold. Also the recording industry.
Have a great day.
No I'm not. You obviously don't understand. Coupling caps have values that pass signals far beyond the pass band. Therefore the exact value will not impact the signal within reason. Speaker crossover caps do determine frequency cut-off. See the difference?
Yes, I did as well. I also did warranty service for KEF. You have no idea who you're talking to here.
Not specifically, but you indicated you used capacitors specifically designed for audiophile consumption. If you really do understand capacitors you would not have touched them. Okay, I don't really care.
Simply because, unlike most circuit designs, Counterpoint depends a great deal on tube characteristics. This is not normal. You have to match the sides and I went nuts doing that under warranty. I'm the one that got them to switch to Sovtek.
So do I, and have for decades. I also back everything up with measurements that by the way, correlate to what you hear.
I redesigned the power supplies on Counterpoint reamps to be reliable and have higher performance, I was authorized warranty. The official upgrades were nonsense and a money grab as far as I'm concerned. Anyway, I know this product inside out, backwards and upside down. Debate if you want. But you are talking to someone who actually knows this industry dead cold. Also the recording industry.
Have a great day.
@anatek So I did order the 100uf 450 Epcos caps along with the BC Components MAL series cap for the 47uf 450 in the power supply to put it back to original with these newer type parts. Those parts should be coming in this week. I will also be putting in a better selector switch since I do remember the original got bent when I was removing the PCB. The power supply timing ciruit still worked well the last time I fired up the preamp. The new heatsink for both types of B+ regulators as we discussed came it along with the Heatsink for the LM350K heater regulator, the preamp did get warm on the chassis when used.
Do you remember the current spec for the heater side of the Counterpoint SA-1000? I don't have the original anymore. I know it uses 3 tubes heaters should be around .9A total, so something a little more than 1A just to be safe if I order an EI PT?
Do you remember the current spec for the heater side of the Counterpoint SA-1000? I don't have the original anymore. I know it uses 3 tubes heaters should be around .9A total, so something a little more than 1A just to be safe if I order an EI PT?
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And I suggest you do something that is considered anatomically impossible to yourself. YOU don't know who you're talking to here either. Could you be ANY more of a pedantic boor?
Hi Drummerboy2,
Sounds good. A new selector would be nice, I never liked the ones they used but then many manufacturers used the same switches.
The heater regulator will run warm. Anything you can reasonably do to lower the temperature is good. Note I said reasonably!
Allow more safety with your transformer. Counterpoint allowed the temperature to run higher and made their own transformers. Failures were not unheard of, more so than any other brand. Some tubes people use draw higher than the rated current for a 6DJ8/6922, and then you have manufacturing tolerances as well. The heater circuit draws the most, but you also have to allow for current pulses in rectification that create I-R losses in the core. If I had one here I would measure the core size (the best indicator of power). One clue will be the mounting hole spacing. Better transformers will run at lower temperatures. E-I cores tend to be better at rejecting line noise as well.
If I were replacing a transformer and have the room, a shielded one (with metal bell (end caps)) would be my choice. As a rough guess I would allow 1.5x on the heater current and see how large that part is. 25% larger is much better than something that can just handle the current, it depends on how much room you have. Don't forget to allow for the B+ current as well.
I'm sure there are folks more skilled at transformer design that can give you a better answer. The following is true. The larger transformers have better voltage regulation and will run cooler. There isn't much difference in price between these ratings, but end bells will increase the price (but reduce radiated hum). I would have to pull out the manual, and even better, measure one that works. I would measure actual current draw and running temperature in addition to the original core size.
Hopefully you find some of that helpful.
Sounds good. A new selector would be nice, I never liked the ones they used but then many manufacturers used the same switches.
The heater regulator will run warm. Anything you can reasonably do to lower the temperature is good. Note I said reasonably!
Allow more safety with your transformer. Counterpoint allowed the temperature to run higher and made their own transformers. Failures were not unheard of, more so than any other brand. Some tubes people use draw higher than the rated current for a 6DJ8/6922, and then you have manufacturing tolerances as well. The heater circuit draws the most, but you also have to allow for current pulses in rectification that create I-R losses in the core. If I had one here I would measure the core size (the best indicator of power). One clue will be the mounting hole spacing. Better transformers will run at lower temperatures. E-I cores tend to be better at rejecting line noise as well.
If I were replacing a transformer and have the room, a shielded one (with metal bell (end caps)) would be my choice. As a rough guess I would allow 1.5x on the heater current and see how large that part is. 25% larger is much better than something that can just handle the current, it depends on how much room you have. Don't forget to allow for the B+ current as well.
I'm sure there are folks more skilled at transformer design that can give you a better answer. The following is true. The larger transformers have better voltage regulation and will run cooler. There isn't much difference in price between these ratings, but end bells will increase the price (but reduce radiated hum). I would have to pull out the manual, and even better, measure one that works. I would measure actual current draw and running temperature in addition to the original core size.
Hopefully you find some of that helpful.
@anatech Thank You for the info, I really appreciate it. With this new info I have a transformer in mind from Edcor and should work very well, just hope it fits. I have a Edcor PT for another project I started but never finished, this will give me an indication if the new transformer I order will fit since its a 300Vdc B+ and 6.3Vdc 2A heater supply.
Would you be willing to check out a SA-100 amplifier that I have owned for many years? If you are, I can send you more information. I reside in Canada.