Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on April 16, 2013, 07:21:22 am
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Just a quick note for those of you who may not have tried this.
I've continued to tweak my D'Mars ODS slowly & allow each of the mod/s a week or so of playing.
I removed as much of the shielded wiring on the clean channel that I could and found it did make a difference in transparency and touch sensitivity. The amp is amazingly touch sensitive and transparent. I think I have shielded wiring to the 33k resistor on V1-2 and shielded wiring to the treble pot only on the clean, IIRC.
So, I then tried removing some of the shielded wiring on the OD channel and that also added some touch sensitivity but with a tiny bit of high end hash and it lost a tiny bit of it's smoothness. I actually liked the OD tone better prior to the shielded wiring being removed as it was smoother OD to my ears.
My current thinking is use as little shielded wiring on the clean and allow more liberty on the OD channel on these clean/OD amps.
I am going to try this approach now on my Tweed BluezMeister and will get back to you.
With respect, Tubenit
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It depends on the capacitance per foot of the type of shielded wire that you are using. Added capacitance can enhance or degrade the tone,depending on where it's used.
Good call on finding out where Tubenit!
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Tubenit - me likey. Clean is clean & aint no fun if it aint got that thing...du wop du wop du wop. Okay just having fun there - you know that jazz song?!
In higher gain overdrives/distortions/fuzzes (think pedal fun we've been having) these smooth out greatly and can even get more musical feedback/bloom simply by turning the tone knob down on your axe right? So it only makes sense that you don't need to "fret" (pun intended) about transparency/touch sensitivity in the same way when playing highly overdriven. You can't hear it the same anyway w/ those settings or pedals and you want that smoothness. I always think Santana and certain Clapton tones here. BUT definitely for that clean channel - you know you want to hear every single detail of that guitar you made or paid a good amount for.
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OK, tried this on my Tweed BluezMeister now also. Similar results. Increase of touch sensitivity and transparency.
NO increase in floor noise which sort of surprised me given the TBM is built into this small 18w tweed style chassis.
Blooming on the OD channel increased perhaps more than doing the same thing on the D'Mars. Cleans are beautiful.
Similar as with the D'Mars ODS, the OD channel got somewhat brighter. I will play it that way for a while and if need be, I can up the smoothing cap value. I may just need to adjust the OD tone stack which I haven't tried yet.
With respect, Tubenit
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On my JCM800 2204, I have twisted two wires, like we do to feed the heaters. One is connected to the input jack and goes to pin 7, the other is hooked up to pin 6 , the other end being carefully taped and hung up somewhere. Good results, tone wise and no noise.
Colas
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OK, here is a visual of the shielded wiring from input thru clean thru FX into LTPI for both amps.
Essentially, input to V1-2 is shielded. From active FX loop to LTPI is shielded. On the D'Mars ODS, from treble to relay is shielded.
That's it! No additional floor noise. I should add that the wiring is somewhat messy but the amps are quieter at idle than the Princeton Reverb I used to own (when on the clean channel) and are louder than the PR was.
With respect, Tubenit
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Have you tried removing these too?
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I have not tried removing them.
D'Mars FX to LTPI is a loooong run & runs by alot of other stuff.
I don't want anymore treble on the D'Mars & the wire crosses a B+ rail and is tight in the relay area.
The TBM FX to LTPI might be feasible? However, it runs close to a tube base and close to filament wires so I decided not to try it.
I think the tone is pretty much where I want it.
With respect , Tubenit
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T do you have an updated schematic I was just curious I was in the process of wiring this one up and noticed on this one. the D Mars that is the coupling cap to V1b is 1.68uf and on mine its 1uf. which one do you like better . Thanks Bill
I was tring to build one that i dont tweek to the max and make my board look messy
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Reply #10 on this thread is the best tweaked D'Mars ODS that does not have an active FX and uses a 5879 in the OD section.
http://www.el34world.com/Forum/index.php?topic=14302.0 (http://www.el34world.com/Forum/index.php?topic=14302.0)
Yes, I prefer the 1.68 uf on V1b cathode. I use a 1uf & parallel a .68uf.
With respect, Tubenit