Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pompeiisneaks on October 13, 2017, 01:47:55 pm
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Hey does anyone have a datasheet on the original CBS fender power transformer specifications? So far all I can find is the classictone version and it has a 6.3v @ 5.5A heater winding, which, with my calculations, could handle the 4 6L6GC (0.9A per tube) and 5 preamp tubes even though the stock fender Bassman 100 has 3. (I'm looking to likely convert one I just bought into a Dumble ODS 100W and just want to use the existing chassis, transformers etc in the amp).
Does the Classictone replicate the existing transformer?
http://www.classictone.net/40-18042.pdf (http://www.classictone.net/40-18042.pdf)
~Phil
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I don't have a data sheet for the original, but I can tell you that the Bassman 100 PT is one heavy duty PT. I have two Bassman 100's and two silver face Twins and they appear to all have the same PT.
One Bassman 100 has four 6L6's and six preamp tubes and it barely gets warm. The other one I would mod to whatever I needed for whatever was being recorded at the time. The last mod was to record a guy doing his tune about a '66 Mustang, so I put a 1959 Marshall circuit in it with four EL34's. He rehearsed and recorded that tune with that amp at full blast and the PT still didn't get hot.
If I were to guess, the Classictone probably isn't as robust as the original Fender. I think Hammond has one rated at more current for the HT, but still 5.5A for the heaters.
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would something like this work ? http://www.ebay.com/itm/1957-Baldwin-41P-Organ-C512-19211-D-Power-Transformer-Tube-Amp-6L6-5U4-/112560203088?hash=item1a351c6550:g:eN8AAOSwAQBZtsmX (http://www.ebay.com/itm/1957-Baldwin-41P-Organ-C512-19211-D-Power-Transformer-Tube-Amp-6L6-5U4-/112560203088?hash=item1a351c6550:g:eN8AAOSwAQBZtsmX)
most tube type organs used many tubes so the filament windings were very robust ..
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would something like this work ? http://www.ebay.com/itm/1957-Baldwin-41P-Organ-C512-19211-D-Power-Transformer-Tube-Amp-6L6-5U4-/112560203088?hash=item1a351c6550:g:eN8AAOSwAQBZtsmX (http://www.ebay.com/itm/1957-Baldwin-41P-Organ-C512-19211-D-Power-Transformer-Tube-Amp-6L6-5U4-/112560203088?hash=item1a351c6550:g:eN8AAOSwAQBZtsmX)
most tube type organs used many tubes so the filament windings were very robust ..
I don't need one, I have one, and just want to modify the amp to use the existing PT and OT with the same 4x6L6GC output tubes, but I'm planning on putting in a Dumble preamp, so it needs 5 preamp tubes instead of the 3 here, So basically, as 2deaf seems to have clarified, I should have the current capacity for the heaters for 2 more preamp tubes... Thanks!
~Phil
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I can't vouch for the PT specs 'cause I turned mine into a 50 watter, but I can say that I enjoyed working with all of that space.
I can't believe it's been 3 years since I built this, but it was definitely an eye opener. Your question brought back the memories.
Please feel free to borrow my layout :l2:
http://el34world.com/Forum/index.php?topic=17872.msg181737#msg181737 (http://el34world.com/Forum/index.php?topic=17872.msg181737#msg181737)
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So cool! Thanks yeah that's right down the alley I'm planning on, glad that others feel gutting the bassman 100 isn't sacrilege :)
~Phil
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Maybe this will help some.
Found new transformer chart for spec purpus only: Last chart
1st chart gives Fender part numbers.
2nd chart is ClassicTone's conversion chart
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I'd say the PT for the SF 100W twin/dual showman/quad/supersix reverb will work for the Bassman 100. The Fender part number is 022756/125P34A (or 022764/125P34AX for the export version)
The choke used in those amps is 022699/125C1A.
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Sorry guys I must not have been clear enough.
I have a Fender Bassman 100 en route that I bought. I want to gut it and use it for a Dumble build. Does the existing PT in the Fender Bassman 100 have enough current capacity to handle the extra tubes (It has 2 12A*7 in it now, but I'll need 5).
I don't need a new transformer, I am trying to ensure the one I have has enough oompfh.
~Phil
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The PT and choke numbers that I referred to above are for 100W amps that have 4 x 6L6s and 4 x 12AX7s and 2 x 12AT7s. What Tx number is on your Bassman PT?
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Sorry guys I must not have been clear enough.
I have a Fender Bassman 100 en route that I bought. I want to gut it and use it for a Dumble build. Does the existing PT in the Fender Bassman 100 have enough current capacity to handle the extra tubes (It has 2 12A*7 in it now, but I'll need 5).
I don't need a new transformer, I am trying to ensure the one I have has enough oompfh.
~Phil
i have one i salvaged out of a 76 bassman 100: it carries part no. 022756 - same part no. as the twin reverb. as already stated, you're good to go. for the one i have, the winder was woodward-shumacher - 606-620 so made in 20th week of 1976.
--pete
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BTW, the OT is a different story altogether - it's massive for 100W: easily a HI-FI grade part if the interleaving was good enough to get the upper pole over 15KHz.
--pete
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I don't yet have it, it arrives on thurs, I did copy the transformer number from the pics and I think i posted that on my first link, but I'll double check when I actually get it.
Thanks for the info guys :)
~Phil
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The transformer you linked in your first post shows 5.5 amps available on the 6.3V filament winding. Each 6L6GC pulls 0.9A and each 12A_7 pulls 0.3A. So, 3.6A + 1.5A= 5.4A should be no problem
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The transformer you linked in your first post shows 5.5 amps available on the 6.3V filament winding. Each 6L6GC pulls 0.9A and each 12A_7 pulls 0.3A. So, 3.6A + 1.5A= 5.4A should be no problem
And Type #47 pilot lamps pull about 150mA. (Although I have some stamped with 300mA, and others at 500mA).
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Thanks, sounds like I'm in like flynn.
~Phil
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Oops. I forgot about the pilot lamp. Might want to use one of these:
https://www.soslightbulbs.com/product/led-lighting/led-lamp/lamp-47-led-equivalent-miniature-light-bulb/ (https://www.soslightbulbs.com/product/led-lighting/led-lamp/lamp-47-led-equivalent-miniature-light-bulb/)
Barry
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Oh those are super cool! I'd guess at 6.3VAC it won't have any problems.
~Phil
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Yep. I always wondered when they were going to make those. I think I'm gonna pick up some of those.
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ouch!! 6 bux for a LED lamp!!??!!
try these! (https://goo.gl/Csy5p8) 10 qty. for same price + 2 bux to ship not 8.
--pete
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Well your price is still better, but that was for a 5 pack, and yeah 8 bucks for shipping something that small is criminal :P
~Phil