Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on October 06, 2011, 12:20:00 pm
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OK, here is my thinking behind this................
I made the Carolina SongBird amp, then changed the position of the tone stack behind the cathode follower which signficantly changed the tone. It had more headroom and added some Marshally type "crunch" vs. the D-style bluesy tone.
I also noticed on the TOS 2CF amp that I have my Master volume after the CF at almost "9" most of the time and instead use the PPIMV to control the volume. So I don't need the MV (probably)
So, I got the thinking what else could I do with the pot? And I had this idea to use a DPDT (which could be relay switched) to actually switch from a Dumblish style tone stack prior to V1b into a Marshall tone stack after the cathode follower behind V1b.
The Dumblish PAB switch somehow renders the bass and mid pots useless. In other words, the PAB partially disconnects much of that type of tone stack.
So, with the Dumblish TS "out" of the signal path, I could add the Marshall tone stack into the signal path using the DPDT.
Haven't done it yet, but will probably try this one out at some point and report. Not sure I have a dual gang 500k pot to experiment with or not?
with respect, Tubenit
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:huh:!!!
got more switches than the lunar command module!
Sort it out Jeff and tell us what you think of it!
I'll copy it somewhere if you get it working!
:worthy1: in advance
Ray
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Man,Don't do this to me!!!! I spent most of yesterday redrawing my TOS schem and layout for the rebuild :sad2: But i wait eagerly for the results.Love your work :headbang: :headbang:
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Cool Jeff there you go thinking outside the box again. You sure come with some good idea,s to try.
As usual we wait patiently for your thoughts on the results.
Thanks Bill :thumbsup: :happy1: :happy1: :m8
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OK, I tried removing the master volume for the clean channel and installed a 5E3 type tone stack. Didn't work.
So, I tried a similar tone stack that I used on Chip's "Double C" amp (schematic in SCH library).
This worked very nicely! When the PAB is switched, it somewhat disconnects the tone stack prior to V1-b & engaged the tone stack after the mosfet cathode follower.
On a scale of 1-10 (10= very dramatic), I'd say this is a "4" & a useful modest but significant tone change.
It adds a very noticeable dash of "chime" and a vowel tone which I like ALOT. It almost sounds like a wah pedal is engaged coloring with the vowel/wah type tone. I am confidant that with this PAB/chime engaged that it would help a solo cut thru the band mix more easily. It surprised me but with this "chime" pot, whether it was dialed to "0 ....... or 10", it was not muddy sounding at all. You could still get a nice transparent tone with it on "0".
I also found that I like the clean better without the master volume. I feel like I perhaps have more headroom & the amp is actually quieter at idle. (and it was already very quiet).
Only downside for me doing this is a really really wish I had the PAB on a footswitchable relay but I don't. :BangHead:
Remember this amp is only about 23 watts, so the PPIMV works just fine for me to control volume. IF this were a 50 watt version of the TOS ......... I might still want a master volume on the clean channel, but you could still add the tone stack.
I have added the schematic and layout here:
http://www.el34world.com/Forum/index.php?topic=11455.msg113204#msg113204 (http://www.el34world.com/Forum/index.php?topic=11455.msg113204#msg113204)
With respect, Tubenit