I have the same desire and the same question, ie, what is an appropriate value for the pot, 50k, 100k, or something else? Can the pot just be inserted before the board, or are other mods needed?
Thanks as always for any help given.
Just add the volume pot before the input on the Spud. No capacitors or anything else needed. The input impedance of the Novar Spud is 470 kΩ so a pot in the range of 10 kΩ to 100 kΩ would work well. Lower is better as long as your source can drive it.
Tom
I've heard that before but don't understand why. Can you clarify why a lower resistance pot is better? Most tube DIY and kits I've built use 100 k ohm pots. -Thanks.
Lower resistance -> lower noise. Thermal noise of a resistor: en = 4*k*T*R. k is Bolzmann's constant, T is absolute temperature, R is resistance. Unit on en is V2/Hz.
Note that lower resistance -> heavier load on the source, so there's a definite trade off there. With a modern opamp output source, I'd go below 10 kΩ if a suitable pot is available. For a tube output stage, 100 kΩ is more appropriate.
Tom
Note that lower resistance -> heavier load on the source, so there's a definite trade off there. With a modern opamp output source, I'd go below 10 kΩ if a suitable pot is available. For a tube output stage, 100 kΩ is more appropriate.
Tom
I bought (4) of the 9 pin Compactron Novar tube sockets from ESRC. They fit perfectly fine. Since I bought 4 I have 2 extra. Just pay for shipping and Ill send you the other 2. Shoot me a PM.
That's odd, I just bought a couple of sets from ESRC a couple of weeks ago and they fit perfectly. Are you certain you ordered the right thing?
Woops, sockets were ordered from "The Tube Center" (off Ebay), which has the same address as ESRC at 6424 Pinecastle Blvd. Orlando. I assume they are the same.
I think it is some kind of vendor mistake, so I'll call them. The packed invoice has the completely wrong part number on it, SK-9, which is a standard 9 pin noval socket on their site. But what came is a 9 pin Magnoval socket. And what I ordered (off Ebay) said:
"9 Pin Compactron SOCKET
Fits 6JB6, 6JG6, 6JE6, 6KG6, 6KV6, 437A, etc."
To confuse matters, 6JB6, 6JG6, 6JE6 and 6KV6 are Novar. But 6KG6 is Magnoval.
However, the ESRC SK-9C 9 pin Compactron tube socket on their site has a picture with obviously too big of pin holes in it: (1st pic attached) And I don't see any Magnoval socket even listed there. Received socket is 2nd pic. Notice the large socket pin holes. Some Chinese sockets state that they fit both sizes, but these sockets just fall off Novar tubes.
Somewhere, the truth must be out there....
I think it is some kind of vendor mistake, so I'll call them. The packed invoice has the completely wrong part number on it, SK-9, which is a standard 9 pin noval socket on their site. But what came is a 9 pin Magnoval socket. And what I ordered (off Ebay) said:
"9 Pin Compactron SOCKET
Fits 6JB6, 6JG6, 6JE6, 6KG6, 6KV6, 437A, etc."
To confuse matters, 6JB6, 6JG6, 6JE6 and 6KV6 are Novar. But 6KG6 is Magnoval.
However, the ESRC SK-9C 9 pin Compactron tube socket on their site has a picture with obviously too big of pin holes in it: (1st pic attached) And I don't see any Magnoval socket even listed there. Received socket is 2nd pic. Notice the large socket pin holes. Some Chinese sockets state that they fit both sizes, but these sockets just fall off Novar tubes.
Somewhere, the truth must be out there....
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Update:
They are sending out some replacement sockets that are tested to fit the 40 mil pins of Novar tubes. And I'm sending the others back. Pretty sure these are more Chinese ceramic sockets though, look identical.
Someone else (on diyA) recently complained about the difficulty of finding reliable Novar sockets anywhere, especially the Chinese ones that didn't fit worth $.02.
Seems the Chinese sockets that claim to fit either Novar or Magnoval don't really fit either. Breaking the bases of Magnovals and becoming loose on Novars after a number of insertions.
I don't see why the standard 40 mil diameter 9 pin Noval socket pins cannot be supplied in the 9 pin Compactron sockets. Do we have to make our own by pulling them out of 9 pin Noval sockets?
They are sending out some replacement sockets that are tested to fit the 40 mil pins of Novar tubes. And I'm sending the others back. Pretty sure these are more Chinese ceramic sockets though, look identical.
Someone else (on diyA) recently complained about the difficulty of finding reliable Novar sockets anywhere, especially the Chinese ones that didn't fit worth $.02.
Seems the Chinese sockets that claim to fit either Novar or Magnoval don't really fit either. Breaking the bases of Magnovals and becoming loose on Novars after a number of insertions.
I don't see why the standard 40 mil diameter 9 pin Noval socket pins cannot be supplied in the 9 pin Compactron sockets. Do we have to make our own by pulling them out of 9 pin Noval sockets?
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Keep us updated on what you received. The right photo clearly shows Magnoval. Very same as:
2PCS 9pin B9D MAGNOVAL Ceramic Tube Sockets for EL504 EL509 EL502 Chassis Mount | eBay
I have on hands both like this one and a Compactron, and it seems the opening for the Magnoval's terminal is a bit bigger. The terminals look very alike, the Compactron's ones just seem having smaller opening gap.
I ordered mine from this evilBay seller:
1PC B9D Magnoval 9pin Ceramic Tube socket for EL504 EL509 Bottom Chassis Mount | eBay
Though being Magnoval these worked quite well, not dead tight but enough to hold the tube.
Another solution is to buy the Magnoval and Compactron sockets but swap the terminals.
Also, look at this one, the openings look smallish, I bet these will work perfect (expensive - made of teflon):
High end Teflon Magnoval 9 pin Electron Tube socket WE34 WE429 8233 6S45P WE418A | eBay
2PCS 9pin B9D MAGNOVAL Ceramic Tube Sockets for EL504 EL509 EL502 Chassis Mount | eBay
I have on hands both like this one and a Compactron, and it seems the opening for the Magnoval's terminal is a bit bigger. The terminals look very alike, the Compactron's ones just seem having smaller opening gap.
I ordered mine from this evilBay seller:
1PC B9D Magnoval 9pin Ceramic Tube socket for EL504 EL509 Bottom Chassis Mount | eBay
Though being Magnoval these worked quite well, not dead tight but enough to hold the tube.
Another solution is to buy the Magnoval and Compactron sockets but swap the terminals.
Also, look at this one, the openings look smallish, I bet these will work perfect (expensive - made of teflon):
High end Teflon Magnoval 9 pin Electron Tube socket WE34 WE429 8233 6S45P WE418A | eBay
Here's mine. The "industrial" version
I'm a little late to the party but I think your Amp looks awesome. I really enjoy repossessed materials. So much so that I bought Pete Millett's "el escorpion" when he listed in on eBay. Well done sir.
The Magnoval tubes use fatter pins. The Novar pins are 40 mil (~1 mm) in diameter. I think I did get Magnoval sockets when I built my Novar Spud. I was able to make it work by pinching the socket pins a bit. It's not an ideal solution, but it can work.
The Chinese ceramic sockets are generally pretty good. At least I haven't had any issues with the ones I've used assuming they fit the tube.
I did see a picture of a regular 9-pin socket where the one of the holes in the ceramic for the tube pins wasn't large enough, so the tube couldn't be inserted. As with so much other cheap eBay stuff, the QC is left to the customer.
Tom
The Chinese ceramic sockets are generally pretty good. At least I haven't had any issues with the ones I've used assuming they fit the tube.
I did see a picture of a regular 9-pin socket where the one of the holes in the ceramic for the tube pins wasn't large enough, so the tube couldn't be inserted. As with so much other cheap eBay stuff, the QC is left to the customer.
Tom
I did get some replacement NOVAR sockets from The Tube Center which look similar to the Chinese ones on Ebay. (mounting tabs are crimped on, similar to the GD ones, but I think a different brand) These are fitting much better than the obviously Magnoval ones I was sent originally. But maybe one in 3 sockets has a rather loose terminal for Novar use, so one needs to check them using a single pin test (old tube pin). These can be tightened with a small screw driver readily. Just plugging in a Novar tube will be misleading, since that won't show up a single loose pin.
I also ordered some GD sockets off Epay and they have mostly too big terminals for Novar, even though they claim to fit 7868 and 6LQ6 tubes besides Magnoval tubes. These sockets look to be hard to tighten. I ordered some 9 pin B9A gold pin sockets too, thinking I could move the terminal pins over to the bigger sockets. Which looks like it would work, but big PITA. But they sent tin plate sockets instead, so everything is going back. Will try again. I'm never buying Novar tubes or sockets again. I can't believe they can't put the right terminals in the sockets or sell the pins separately, but messages to the Chinese Epay sellers are useless.
I also ordered some GD sockets off Epay and they have mostly too big terminals for Novar, even though they claim to fit 7868 and 6LQ6 tubes besides Magnoval tubes. These sockets look to be hard to tighten. I ordered some 9 pin B9A gold pin sockets too, thinking I could move the terminal pins over to the bigger sockets. Which looks like it would work, but big PITA. But they sent tin plate sockets instead, so everything is going back. Will try again. I'm never buying Novar tubes or sockets again. I can't believe they can't put the right terminals in the sockets or sell the pins separately, but messages to the Chinese Epay sellers are useless.
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