Well, the question is -- 6N30P unbalanced in/balanced out line amp for my push-pull 2A3 amp? Or plate-choke loaded 6V6 line amp (unbalanced in and out)?
But wait... Somebody here is going to have this great idea for how to take the 6V6 line amp and add a balanced out... Oh no....
But wait... Somebody here is going to have this great idea for how to take the 6V6 line amp and add a balanced out... Oh no....
I was afraid of that.
But no, I don't want to spend the money for a pair of OPT's. Tell you what...
I have a pair of old UTC CG51AX interstage transformers. The primary is 22H measured on my LC meter, DCR is 1050 ohms. I can commit these to the cause. I would use only their primaries as the plate loads.
I figure 22H and DCR = 1050R loading a triode with an rp of 2k ohms will give a -3dB point of about 7 Hz.
Can these IT transformers deliver their inductance under a 22mA load? Well I don't know. Is there a way to infer from the L and DCR what the current capacity is?
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But no, I don't want to spend the money for a pair of OPT's. Tell you what...
I have a pair of old UTC CG51AX interstage transformers. The primary is 22H measured on my LC meter, DCR is 1050 ohms. I can commit these to the cause. I would use only their primaries as the plate loads.
I figure 22H and DCR = 1050R loading a triode with an rp of 2k ohms will give a -3dB point of about 7 Hz.
Can these IT transformers deliver their inductance under a 22mA load? Well I don't know. Is there a way to infer from the L and DCR what the current capacity is?
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if they're gapless , saturation (read- distortion) is inevitable
but you'll not fry them ......... so , you can try
go here : http://vt52.com/
look in diy corner for software tools
but you'll not fry them ......... so , you can try
go here : http://vt52.com/
look in diy corner for software tools
Sorry, did not see any software tools. What am I looking for?
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Since the primary was intended to be a plate load (the secondary is a push-pull winding), wouldn't that primary work as a plate choke? I have no idea if there is an air gap in the core. There just isn't much info available for UTC CG51AX.
Back in 2005 on another forum, someone wrote:
"I have a pair of UTC CG51AX ITs (sorry, no link) which according to UTC can adapt just about anything to a 2A3, 6L6, or similar. The catalog doesn't provide impedence specs but claime to "match single tubes like 6C5, 6C4, 12AU7, 2A3, 5814A" to tubes like "2A3 or 6L6". There are two primary connections and 5 (I believe) secondary connections, one is ct. Ratio is specified as 2.8:1 or 3.1:1 primary to 1/2 secondary. Also the IT is rated at 5W."
I don't know how 5W translates to max current capacity before core saturation. Just Ea times Ia?
What is the lowest plate current you'd use with a 6V6-triode in this circuit?
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Info on the CG51AX from an ebay auction:
"The CG-51AX is a Single Plate to Push-Pull Grids Interstage Driver transformer. The Primary was designed for a single 6C5, 12AU7, 6A6, 6N7, 45, 2A3 or other tubes with a maximum of 5 Watts (!); to couple to the Grids of 45, 46, 2A3, 6L6 or other push-pull audio output tubes. The Secondary can be configured for a Ratio of 2.8:1 or 3:1 Primary to 1/2 Secondary, making these interstage driver transformers very versatile. Maximum Level is 5 Watts on the Primary. Frequency Response is actually impressive for a Single Plate to Push-Pull Grids transformer that can handle significant unbalanced DC in the primary, listed as 40-10KHz + or - 1 1/2 db. Each of these vintage UTC transformers is physically about 3 1/4"H with base width of 2 9/16" x 2 9/16" which have mounting center holes at 2 3/32" square. "
"The CG-51AX is a Single Plate to Push-Pull Grids Interstage Driver transformer. The Primary was designed for a single 6C5, 12AU7, 6A6, 6N7, 45, 2A3 or other tubes with a maximum of 5 Watts (!); to couple to the Grids of 45, 46, 2A3, 6L6 or other push-pull audio output tubes. The Secondary can be configured for a Ratio of 2.8:1 or 3:1 Primary to 1/2 Secondary, making these interstage driver transformers very versatile. Maximum Level is 5 Watts on the Primary. Frequency Response is actually impressive for a Single Plate to Push-Pull Grids transformer that can handle significant unbalanced DC in the primary, listed as 40-10KHz + or - 1 1/2 db. Each of these vintage UTC transformers is physically about 3 1/4"H with base width of 2 9/16" x 2 9/16" which have mounting center holes at 2 3/32" square. "
Oh, you didn't have to make that so difficult...
http://vt52.com/diy/tips/platechoke.xls
It was in Tips & Tricks section.
http://vt52.com/diy/tips/platechoke.xls
It was in Tips & Tricks section.
Interesting. It says that for rp = 2k and L = 22H that the -3dB point will be 14Hz. That's not so great, is it.
Why is that so different from the other equation I found?
-3dB down point: X_L = DCR + 2πfL = rp
Is that one wrong? It predicts a -3dB point at only 7Hz.
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I'll go with the worst-case scenario and figure on -3dB at 14 Hz. That's not so great...
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BTW, lots of cool stuff on that site! Thanks.
Why is that so different from the other equation I found?
-3dB down point: X_L = DCR + 2πfL = rp
Is that one wrong? It predicts a -3dB point at only 7Hz.
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I'll go with the worst-case scenario and figure on -3dB at 14 Hz. That's not so great...
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BTW, lots of cool stuff on that site! Thanks.
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Using the VT52C.com spreadsheet, the other choke (60Hz 730R) looks much more promising. -3dB at 2 Hz.
So there it is.
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Oh, and my apologies for my grumpiness. It was early in the morning here...
So there it is.
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Oh, and my apologies for my grumpiness. It was early in the morning here...
Oops. Make that 6Hz. I had the DCR of the choke in the place where the tube's rp is supposed to go. (Duh)
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