Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on February 25, 2015, 05:32:44 am
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The original D'Mars had a 5879 OD. I used a D'Lator with it and it sounded great! However, I got lazy about hooking up the D'Lator and decided to put the active FX on board and removed the 5879 in the OD. And I liked how that worked out. (all done with original Hoffman style D'Mars turret board)
Long story short, I slowly tweaked my original D'Mars for almost two years. Some of that was prompted by changing speakers or effects pedals. Then I sold it and rebuilt it with neater wiring and added a 5879 back into the OD section.
So, this one has both a 5879 and active FX on board. I'm really happy with the tone. The original (modded) D'Mars clean channel turned out better then this one has & is more musically sweet, IMO. However, the 5879 OD channel has something of a "vowel" tone with the 5879 in the OD section & perhaps has a little more sustain. More then not, overall, this one sounds much like the original modded one I just sold. That informs me that it's pretty easy to reproduce the tone in a new build. The layout is different and the wiring is slightly neater so I don't regret building it.
I like Hoffman style turret boards. They are very quiet. However, because I wasn't sure how the 5879 OD with FX on board would sound, I used a parallel turret board in case I ended up switching stuff out (which is easier with paralleled turrets). Now that it's a proven build, it could be done with Hoffman style board.
Over the two years, I've learned that the D'Mars benefits from tweaking depending on the speaker that you are using and even the effects pedal you are using. This turned out very quiet at idle like the original one did. It has the best "quiet at idle per volume/loudness" factor of any amp I've had.
with respect, Tubenit
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I did some things different this time. I put the 5 pin DIN jack (for the 3 button foot switch) on the back.
I added a presence pot on the back. That probably wasn't needed as I like it best in one specific position so the original fixed resistor and cap on the D'Mars was just fine.
I used a 22k fixed resistor to ground instead of the FX send pot. The FX send pot was very quiet to a point but beyond that point added unwanted noise. I think this was useful.
Just like on the original D'Mars the OD drive pot was very quiet to a certain point but beyond that point it also added unwanted noise. So, in light of that, one could use a fixed resistor for the OD drive pot and that would be OK, IMO. You have limited adjustment for the OD drive pot & functionally it's pretty much a set and forget.
I also discovered that adding a .001 cap paralleled to the FX "parallel" resistor helps the tone by somewhat smoothing the tone out. Not sure why that would smooth anything but it seemed to.
I added a PPIMV and was uncertain how I would like that given the FX level pot makes a wonderful master volume. However, the PPIMV has proven useful. It will preserve my hearing (since I have some hearing loss) and it does have a sweet spot range without being turned all the way up.
The chassis photo shows that the 5 pin 270 degree DIN jack isn't installed and the last relay isn't installed or hooked up. The layout is different then the original one. However, the original layout and this one are comparably quiet at idle.
With respect, Tubenit
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Since I rebuilt this into the same type chassis, I just used the same combo cab for it.
With respect, Tubenit