2off 470k safety resistors added in parallel to a 100k pot gives me the number 70kohms, which is very near the original 68k grid leaks, if I'm following what's going on and the safety resistors are in parallel as I think they are?Ok, I think I see the question. Yeah, a 100K dual-gang pot with an appropriately high resistance safety resistor (470K) seems correct. You still want the 470K "grid stop" resistors.
2off 470k safety resistors added in parallel to a 100k pot gives me the number 70kohms, which is very near the original 68k grid leaks, if I'm following what's going on and the safety resistors are in parallel as I think they are?
If I've got that right I'll be pleased
Cheers I used it as a template on a Weetabix box so with all the parts in place I'll get the iron in ok if I work in order and as for labelling, mmm, I'm not a Fender purist by any means so I'll wait to see what size font/how many letters I've room for before I give them names although the micro Deluxes I built have the pre amp volumes named as gain as I couldn't fit 'master volume on 2 lines so called the latter 'volume'. I'll aim to label them as per Rob.Heh, it looks nice. I'm not aware of what would keep it from working -- but my awareness may be limited. Mine was made Fender-style, 'upside down' in a Marshall chassis, and so I'm not able to rotate all the wiring paths, for example. And my brain is too stubborn to let Rob's Marshall-ized layout (flipped north-south) help.
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Folks who've built in a right-side-up Marshall chassis may have better insight; our friend @joulupukki is good at wiring details, I know.
On a much less important note, how are you actually labeling your three volume knobs? I suspect you saw my goofy thread about their sonic functions, and how Rob's 'bright' volume pot was just a carryover from the original two-channel Bassman which also had a normal channel. Folks suggested lots of good (and many quasi-humorous) options there. As someone said, it doesn't matter; you'll know what they do anyway. I'm just curious.
Yeah, seems like it should work fine. It might get tight wiring the pots and the only thing really to consider there is serviceability in the future. At the bottom of this post there’s a picture of the front of my amp.Is there any reason that layout won’t work? The 2 small circles bottom left would be an nfb switch and tone stack cut and I get room for nice graphics, the v1 bypass cap switch would go to the rear.
A funny old world but my old mate reckons to have done some custom faceplates for 'Matamp' and mentions "used a laminate sheet to engrave the top layer off giving white letters on a black background or other colors".I emailed my old workmate and he confirms he owns a co2 laser but hasn't replied to my faceplate proposal yet, tho I have some persistence in my tool bag so will work on that.
I've re-read your thread I remember it starting but at the time I was looking at building my first amp and the Bassman was too complicated for me so I admired your woodwork photos whilst scratching my head at terms such as 'ltp & nfb' etc, I mean, a long tailed pair when there's the one valve, and 'negative feedback' had me imaging a screech going from high to low.I'm glad the photos helped! 3" deep would be nice. I used the Hammond 1444-1372 (13" x 7" x 2"). It definitely got cramped trying to fit the Carling power switch in there without it getting too close to the edge. Which reminds me, I should probably add some heat shrink around those terminals just to be on the safer side.
I have no idea what your talking about building an amp from scratch and being discriminating about the parts you use indicative of caring and I say, GOOD ,Great I am proud of you guys that build amps and old fashion reverbs for yourselves. I am happy for you.I'm preparing to start an attempt at the RobRob Bassman Micro, I've ordered the parts from Tube-Town in Germany so will have the correct OT/choke and the PT is the Hammond 370AX which has a CT on the 6.3v secondary, the rectifier valve is made by 'Zaerix' but it was that or a JJ one which was 10 euro cheaper so thought I'd play it safe.
The valve bases will be the ones mounted from the top unfortunately (Belton VT9 ST2) I'd have preferred the internal mounts but it'd have meant another order elsewhere.
I've oak left to make a cab with that matches the cab one of my Deluxe Micro's uses, and have ordered a 1mm sheet of aluminium for the chassis (1.5mmm is a pain to bend without a proper bender )
I'd like to use an NFB switch and make the pre amp bypass cap switchable and possibly have a switch on the input jack for lo/hi inputs but will wait till I've a chassis in hand to see what room I've got
I'm looking forward to this
Usual edit, I'd like the version 2 'lar mar' volume arrangement so have a 250k dual pot on its way, but it's linear not a log one as they had no log ones.