Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ncusack on February 25, 2011, 11:58:42 am
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Hello,
I've been researching for a while now how I can use a set of transformers I have that were originally used for a 5E3 Deluxe. They are a Hammond 272DX PT and 1750E OT. I want to do something different than a 5E3 and came across a few ideas for a 6V6 based matchless spitfire. I think this idea may be a good task for this transformer set and would like to know what you guys think.
Here is the original schematic (http://i53.tinypic.com/ir5mkh.jpg)
and here is my slightly modified version (http://i55.tinypic.com/51eqmw.jpg)
My Changes
-boost/voicing switch where you will have a lower gain just 1k cathode,normal the 1uf//1k and bass boost 10uf//1k options.
-10k instead of 9.1k in the B+ rail because its what I have.
-Lowered the coupling caps to the power tubes to 33n instead of 100n because its supposed to fix some issues with the bass
-Low input jack cause the 6dB drop option can't hurt
Im just wondering if you guys think this will work out and if there are any changes I might want to plan for. I still need to order components and I plan to grab a few extra caps and resistors for tweaking but any suggestions you guys can make will be welcome.
Cheers,
Neill
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I would suggest considering the LarMar PPMIV with this amp or if you still want to use the crossline mstr vol that you use one of Hoffman's 1M pots with the built in spst (which is what I did with my Carolina Blues Special amps). I found the LarMar very useable but almost never used/engaged the crossline with the spst 1M pot.
Also keep in mind that the paralleled 12A_7 into the LTPI was designed more for EL84's which are more easily overdriven then the 6V6 tubes.
If you want some other amp ideas using that PT & OT ......... give us some idea of the type of music you'll play. The SCH library has quite a few 6v6 cathode biased ideas in there.
With respect, Tubenit
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For the most part I enjoy playing blues but with project im just looking for something different. As I said the transformers were from one of my failed early 5e3 builds and im looking for something a bit different but still on the simple side of things. I've been trolling through the schematic library and found a number of interesting builds but in this case it looks like the 1750E becomes the issue. Its smaller than the typical deluxe reverb OT I see used in a lot of the schematics and it has a higher pri impedance. Maybe it's not that big a deal but i guess thats why im here asking questions.
In the case of the PPIMV you suggested from your CBS is that the switched 1M pot design with dropping resistors just after the coupling caps? There are a few versions of the carolina blues amp in the library so im not sure which method your referring to. A schematic would be cool if you can point me in the right direction.
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Scratch that i think i found it is the larmar the dual ganged 250K with 2.2Meg resistors in parallel?
Also if you want a list of the stuff I have on hand and would like to incorporate into this build heres what i have.
Hammond 272DX
Hammond 1750E
Pair of EH6V6 power tubes
Number of NOS 5Y3 tubes
EH 12AY7 tubes
Couple of 1M-audio pots
Hand made 12x8x2.5 Alluminum Chassis
Various resistors and Caps
I also have a 100 dollar gift card for tubedepot thats burning a hole in my pocket too
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larmar the dual ganged 250K with 2.2Meg resistors in parallel?
Yes, I am suggesting the larmar instead of the crossline (with spst like in the CBS).
Perhaps look at the Texas Raptor in the SCH Library? Simple build and it sounds good, IMO. You can do it without reverb.
http://www.el34world.com/Forum/index.php?topic=2442.0
Just a thought to consider. Not pushing anything at all.
With respect, Tubenit
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Happen to have any sound clips of the Raptor? I've heard a few of the spitfire and like it and the use of 6V6's is supposed to make it even better. Im also partial to a single tone knob something about the simplicity of it works for me.
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I don't have any decent recordings of the Texas Raptor since I built it for my son and have since rebuilt it (at a later time) into the Tweed OD lite Reverb for him.
Sounds like your Spitfire with a LarMar may be a good choice for you? The 6V6's are a great tube. My guess is you will find it cleaner sounding than the Spitfire sound clips you've heard with EL84's.
With respect, Tubenit