Man, this thread really took on a life of its own!!
To answer ZMAN01's original question... I know exactly what you are talking about. Digital audio does sound "sterile" compared to analog sources, and I have always struggled with that as well. It is why I never gave up my turntable and vinyl. It seems that the causes of this have been taken up by the various other posters to this thread!
A good tube buffer DOES help alleviate the problem, though.
I got the Yaqin CD1, with the JAN/Phillips 6922 tube, and I am very happy with it. You should be able to find it very easily on Ebay, although the JAN/Phillips tube probably won't be the tube that comes with it. I got them both as a package at the Pacific Valve & Electric Company's website, at www.pacificvalve.us.
I saw the auctions at Ebay at the links you posted, and I would have to agree with the other posters here that they look like cheap DIY junk that someone put together in their garage. You would be wise to go with the Yaqin instead. You can read more about it at the Pacific Valve website.
Good luck.
To answer ZMAN01's original question... I know exactly what you are talking about. Digital audio does sound "sterile" compared to analog sources, and I have always struggled with that as well. It is why I never gave up my turntable and vinyl. It seems that the causes of this have been taken up by the various other posters to this thread!
A good tube buffer DOES help alleviate the problem, though.
I got the Yaqin CD1, with the JAN/Phillips 6922 tube, and I am very happy with it. You should be able to find it very easily on Ebay, although the JAN/Phillips tube probably won't be the tube that comes with it. I got them both as a package at the Pacific Valve & Electric Company's website, at www.pacificvalve.us.I saw the auctions at Ebay at the links you posted, and I would have to agree with the other posters here that they look like cheap DIY junk that someone put together in their garage. You would be wise to go with the Yaqin instead. You can read more about it at the Pacific Valve website.
Good luck.
The circuit given in post 30 looks barmy to me. The lower valve is a poorly designed cathode follower followed by a volume control. At some volume settings this will be an anti-buffer, because the output impednace is greater than the input impedance!
The upper valve appears to do nothing apart from send an amplified copy of the signal into the supply. R1, when present, just sets a DC bias for the 33uF (electrolytic?) output cap.
This cannot be the circuit of a real product, unless the seller is very stupid or very cynical.
The upper valve appears to do nothing apart from send an amplified copy of the signal into the supply. R1, when present, just sets a DC bias for the 33uF (electrolytic?) output cap.
This cannot be the circuit of a real product, unless the seller is very stupid or very cynical.
That output pot always bothered me and would seem to undermine the buffering aspect! R1 on that schematic was a mistake on the one I got. I can't explain the error, but I'll update the schemo. There are a lot of oddities, 10k on the input (which is an smd on the bottom of the board) and the 50k output pot which seems like an after thought.
In trying to decipher the circuit design, I came across this:
PS-6 & Aikido Split-Load Phase Splitter
Also, the coupling caps are in series apparently a 1uF and a .33uF non-electrolytics.
I couldn't edit post 30, so I'm posting a corrected schematic.
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I don't know what the designers had in mind.
I have thought about using this thing as a buffer between a guitar preamp I built years ago, which is plate out and which also has a volume control on the output, to give a better impedance match to a console input. So how about:
1. Eliminate the output pot
2. Eliminate R2
3 Eliminate C3
??
Also the tubes are Chinese 6N3, which I believe is similar to 2C51.
I have thought about using this thing as a buffer between a guitar preamp I built years ago, which is plate out and which also has a volume control on the output, to give a better impedance match to a console input. So how about:
1. Eliminate the output pot
2. Eliminate R2
3 Eliminate C3
??
Also the tubes are Chinese 6N3, which I believe is similar to 2C51.
Nope, just the board and tubes. It does have LEDs under the tube sockets for that moody glow. They are wired on the heater circuit. I'm thinking of ditching those and a resistor tying the heaters to ground and running them on DC.
But as I said before, it was pretty inexpensive when I picked it up. Any thoughts on modding it?
We had a moto in a mach. shop where I once worked. "If you can't make it right, make it bright."
jeff
Great to see the whole hearted discussion!A good tube buffer DOES help alleviate the problem, though.
The Yaqin CD-1 looks like a much more decent unit. Good to know that you are enjoying it, and thanks for the suggestion. Ebay prices are much lower than Pacific Valve, though... hope it's the same stuff?
After some other projects, I took another look at htis (and saw a thread on a different 6N3 based buffer with DC-DC converter.
I stripped out the 10k resistors on the input and connected to a guitar pre-amp I have which is plate out with a volume pot on the output. Actually does sound better through the buffer and the pre-amp "drive" and "volume" controls are now easier to manipulate with the buffer in between, I get less wild variation on a console input. "better behaved" if that makes sense. (the preamp is from a 1992 Electronic Musician article, very similar though to the Fred Nachbauer McTube.)
I am next going to remove the 10k resistor on the output and the out put pot (which I just left wide open), and also remove the .33uF cap (has 1uF and .33uF in series on the output.) and see how that sounds. Then it will be pretty much a cathode follower buffer. Still no idea what the upper tube is supposed to be doing.
The plate and cathode resistors actually seem OK as is. (82k and 2.2k)
I stripped out the 10k resistors on the input and connected to a guitar pre-amp I have which is plate out with a volume pot on the output. Actually does sound better through the buffer and the pre-amp "drive" and "volume" controls are now easier to manipulate with the buffer in between, I get less wild variation on a console input. "better behaved" if that makes sense. (the preamp is from a 1992 Electronic Musician article, very similar though to the Fred Nachbauer McTube.)
I am next going to remove the 10k resistor on the output and the out put pot (which I just left wide open), and also remove the .33uF cap (has 1uF and .33uF in series on the output.) and see how that sounds. Then it will be pretty much a cathode follower buffer. Still no idea what the upper tube is supposed to be doing.
The plate and cathode resistors actually seem OK as is. (82k and 2.2k)
NOTE: Attachment is the original unmodified circuit. The schematic I originally based the drawings on was incorrect.
Yes, I removed the input resistor (R2 on the schematic) and the resistor in series with the cathode R8, bypassed the connection from the plate of the top tube, and replaced both C2 and C3 with on 1uF capacitor. I did this for one channel only. I admit, I was unaware of the connection to the top tube plate, until I started removing the two capacitors. I've attached a new corrected drawing. The attachment is the original circuit.
I'm using this board to buffer the output of a tube preamp, which is plate out (12AX7) through a potentiometer. I'll compare the modified channel to the unmodified channel (except for the input resistors which made no sense to be so small and have been removed from both channels.)
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