My preamp uses a 6X5GT rectifier and wanted to know if I could wire the preamp to also run a 6BY5GA? Reading the data sheets it looks like I need to tie pins 3 and 4 together to have a connection to plate #2 (pin 3 on the 6X5GT and pin 4 on the 6BY5GA), and pins 1 and 8 so cathode #2 on the 6BY5GA is connected. Based on this it looks like I could switch tubes with no problem.
I’m using an Antek AS-05T280 on the 260V tap. The transformer is rated at 50va and 2amps on the 6.3v taps.
Should work, but you haven't said why you need a bigger rectifier. I would rather just pop in a 6AX5 and not rewire.
The other point to watch out for is the value of the reservoir capacitor.
The 6X5 allows use of 32uF.
The 6AX5 (and 6BY5) should be 10uF.
The 6X5 allows use of 32uF.
The 6AX5 (and 6BY5) should be 10uF.
6AX5 has a 1.2A heater current. You could take a 7-pin socket for a 6X4 and attach that to an octal tube base and plug that into the existing rectifier tube socket. 6X4 has 600mA heater and is a bit beefier than the 6X5.
Just following up, has anyone successfully converted the 6X5GT rectifier tube socket over to accept the 6BY5GA? I see they have different amperage (electrical) requirements, but what did you do mechanically speaking? The consensus seems to be to connect pins 1&8 and 3&4 since the two tubes have different pinouts. However, according to this 6BY5GA datasheet, pin #3 should not be used as a tie point. So, has anyone successfully done this with pins 3&4 connected? Did it cause issues or work just fine? Just wondering if the advice on the 6BY5GA datasheet not to tie pin #3 is a hard/fast rule that will always cause permanent damage, or just precautionary advice that hasn't really effected anyone's positive outcome with this conversion.
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Looks safe to use pin 3 as a tie point. both the 6BY5G and 6BY5GA datasheet show nothing at pin 3. Warnings like that on the datasheet were for an entirely different situation, with certain manufacturers deviating from spec for whatever reason, and repairman with a list of tube substitutes to look through for what they had in stock. Very different from how we DIY today.
Better add up the current requirements of the rest of the tubes in your preamp. The transformer is probably dimensioned to supply that current plus the 6X5 & not a lot more. 50 va is a rather small transformer, with your sub'd in alternative it could go into a slow overheat & fail.🙂
The filament rating of the transformer and the two leads I'd be using are rated 2A each? So (I believe) the blue and green leads should be sufficient.. Besides the rectifier tube, it'll be running a quad of 6SN7GTB tubes on a preamp board. Please correct me if I'm wrong, or missing anything that would prevent this from working. Thank you. Link to transformer datasheet: https://www.antekinc.com/content/AS-05T280.pdf
It's also good to know that tying socket pins 3&4 shouldn't cause an adverse issue despite what the 6BY5GA datasheet says. Thanks leadbelly!
It's also good to know that tying socket pins 3&4 shouldn't cause an adverse issue despite what the 6BY5GA datasheet says. Thanks leadbelly!
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The quad of 6SN7s needs 2.4A. Just looked at your pdf, the transformer has two of those 2A winding's
Your verbal description didn't say that, all very confusing. So you could spread the heaters around & come up
with something that would work. The 6BY5 is a brute force pair of diodes, something required for TV Damper service.
But usually only one diode is required in that application. The 6BY5 has very large cathodes,
forward drop should be less than a 6X5. But otherwise, just overkill in a preamp.
What is your objective other than an ordinary preamp? Sounds like you have one to stuff into that socket!!
Your verbal description didn't say that, all very confusing. So you could spread the heaters around & come up
with something that would work. The 6BY5 is a brute force pair of diodes, something required for TV Damper service.
But usually only one diode is required in that application. The 6BY5 has very large cathodes,
forward drop should be less than a 6X5. But otherwise, just overkill in a preamp.
What is your objective other than an ordinary preamp? Sounds like you have one to stuff into that socket!!
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2.4 + 1.6 = 4A [2A+2A]
Why shouldn't this work? It seems pretty straight forward unless I'm missing something. What do you mean I could spread the heaters around to make something that would work? I thought that was the beauty of this particular transformer/tube pairing. It appears to be plug 'n play once the pins have been bridged and electrical requirements met which they appear to be. I agree it's a lot of juice- but the goal of this project was never an ordinary preamp but (comparably) one without forward drop and complete, sustained musical authority and impact even in the most difficult or demanding passages.
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Has anyone done this conversion successfully?
I am guessing this is related to the SP14 preamp.
Don Sach said: "I have modified the preamp to take a 6BY5 rectifier because it sounds better and you can source 6BY5 tubes for $12 or less."
He also said: "I will NOT share the details and I will NOT modify any preamp that I did not build."
So, I am guessing that people using the SP14 preamp kit would like to try the mod.
I am guessing this is related to the SP14 preamp.
Don Sach said: "I have modified the preamp to take a 6BY5 rectifier because it sounds better and you can source 6BY5 tubes for $12 or less."
He also said: "I will NOT share the details and I will NOT modify any preamp that I did not build."
So, I am guessing that people using the SP14 preamp kit would like to try the mod.
That could work, but the rectifier often gets it own heater winding. The argument is that the switching noise from the rectifier can make it into the heaters of the signal tubes and into the signal.
Has anyone out there tried this mod with success? If so, was there more involved than just jumping pins 1 & 8 and 3 & 4?
Hi,
Don Sachs uses the SP14 as a starting point for his DS2 preamp. I believe that he used the same power supply transformer. He did this mod on later units, and I did it to my DS2. Hope this is helpful to some. BTW, it definitely made an improvement.
Don Sachs uses the SP14 as a starting point for his DS2 preamp. I believe that he used the same power supply transformer. He did this mod on later units, and I did it to my DS2. Hope this is helpful to some. BTW, it definitely made an improvement.
I actually don't recall the exact improvements, but generally speaking more current means more headroom, better dynamics. I'll see what Don Sachs said, he wanted independent confirmation and with the excavation of amplifiers, we were running identical equipment, down to cabling, at the time. Generally I do recall his claiming a 10%, and MAYBE he said a 10-15% improvement over all. It was not as dramatic as the later ODAM caps, but it was well worthwhile, IMO. Will search for Don's opinion on it later.