Musicmaster Bass to guitar friendly specs.

[lowatter]

Hi guys...I haven't been around here for quite a while and I thot I'd pop in to ask if anyone has any tweaking suggestions to make this Musicmaster Bass more suitable for guitar. I did a 5E3 tonestack mod, added a internal fuse block and removed the death cap. I also added a 1M on input 1, removed R1 then jumpered it and replaced C3(coupling cap) with a .022 cap. The 12AX7 and 1 of the 6AQ5A's are the original RCA's and I just placed a new Sylvania for the 2nd power tube.
If anyone looking over the schematic has any other suggested mods, I'd really appreciate it. It still really lacks on bottom end with a known efficient and great sounding 12" CTS driver. I'm aware that I should replace the power caps before I pass judgement and I was thinking of 33's/450V's. Thanks for any help and best wishes-Dan

Here's the schematic...
BTW-I picked this guy up for $37.00!

[eleventeen]

DEFINITELY the right price!

Fix it and sell it on ebay, I've seen them go for near $500. That could buy you either a heck of an amp, or most of one, or a heck of a lot of parts. I've always considered them pretty glurky.

[Dave]

The V1 grid already has 470k reference to ground, so the 1meg you added is not going to have the desired effect.
However, I would jumper the C1 and ditch the R3 anyway to make the input more typical.
If the amp was designed as a bass amp, it seems wierd that it wouldn't have enough bottom end.

Dave

[bigdaddy]

I bought a few of the other 6V6 models and turned them into useful gigging amps. I personally would buy a new faceplate and make an 18 watter or something with a pair of EL84s out of it but save everything else.

I used an Allen Princeton PT and Deluxe OT and made a one channel deluxe out of it. Put in an old Jensen C12N and it was perfect for all my gigs. I had a BF Deluxe that was too loud, this was just a tad lower in volume for some reason. I eventually used some champ amp back panels because the drummer would complain, he'd get a lot of the sound thrown back at him with the completely open back.

Just punch another 9 pin hole for the phase inverter. You can also just use one input and have a volume, treble and bass control, that's what I did.

[lowatter]

Thanks Dave, I forgot to add to my original post that I did remove R1 and jumpered. I edited the post. BTW...this amp is(I've read) considered to be not exactly one of the best bass amps made. They make a decent guitar amp platform...albeit simple.

Eleventeen...yeah, that's what I intend on doing with it. I'm going to put it towards a Hot Rod Deluxe or perhaps a Blues Jr.

bigdaddy...I'm trying not to take on any more major mods/builds. I have way too much honey-do stuff to do and I simply can't find the time. The 18W Stout(Blues Bandit) I did build took alot of time and I'm pretty burned out from major projects. Thanks for the suggestions though. They were pretty much what I was thinking too if I had the time.

I would'nt be looking for another amp if it wasn't for the fact that my Stout doesn't have reverb or that Fendery gangle when I want it. I was thinking that maybe just adding a Hammond reverb unit to the Stout might be another option.

Here's some of the projects I've worked on lately...http://www.flickr.com/photos/10000602@N04/

[tubenit]

You have some remarkably nicely done projects there. Mighty fine guitar work for sure. Impressive stuff.

with respect, Tubenit

[bluesbear]

I wouldn't mess with the 6AQ5 version. Too rare! There are a bunch of 6V6 versions floating around but very few 6AQ5's. I got one for helping my bass player move. I gave it too my dad since he already had a Musicmaster bass guitar. It made for nice set!
I agree with eleventeen, sell it and get something commoner and better for fiddling with.
Dave

[Dave]

I have to say that I agree with a couple of the other guys on here. You might well be better off to restore it back to stock and sell it and use the proceeds to buy something much nicer.
There are plenty of amps out there that are pretty well worthless that you can experiment with.

Dave

[lowatter]

Thanks guys and again special thanks to Tubenit as your help and many others here helped me soo much with my Blue's Bandit amp. That amp has operated flawlessly and sounds incredible. I appreciate your kind words about my projects. Playing the Studio and the Jr DC over my 18W is a feeling of satisfaction that's hard to describe.
I'm keeping all the original componants with the Musicmaster Bass amp and I'm only trying to get some better volume and bottom end out of the amp as both are really sufferring still. The power caps drifted down to 17mfd's and I've yet to check voltages but I'm pretty sure there's some issues there. After I get the amp "gigable", I will ebay it towards a Blues Jr or perhaps a HRD. I couldn't in clear consience sell it in the state it's in as far as it's operation is concerned. I'm going to order up a multisection cap 1st to see what happens. I'll re-post when I get there. I really appreciate the input.

[bluesbear]

I don't believe you can get this amp gigable. It's far too weak, even with new tubes and caps. I know; I tried. I agree; bring it up to original specs. Just don't expect much. That's why I say they're worth more as collector's items than as amps. I expect the 6V6 version is far different. I'm talking about the 6AQ5 version only.
Dave

[lowatter]

Thanks Dave. That's the first time I heard that about the 6AQ5A's. That's going to change my whole perspective on the amp. I may do just what you say and return it close to the original specs and off-load it. I read a few "bay" seller's descriptions and that was never said about it. I'll check harmony central too to see if mine compares to others for stock performance.

[bluesbear]

It's not the 6AQ5's, it's the amp as a whole. I had an old Gibson Skylark with 6AQ5's that was sweet, not very loud but the tone was good. I just think this amp was a poorly conceived idea and poorly designed product. Yes, even Fender had their share!
Dave

[lowatter]

Just an update...
I tried using a Zoom GX-4 multi-effects in front of this amp and, whoa! Way more volume that I was looking for and tone for days. I'm going to try placing the original CTS driver back in now to see what it can do with it as far as saturation distortion. The CTS driver in it now is a great driver in other applications and is(probably) 30-50W from an Ampeg stack from the early 80's. This particular driver was used in some mid 70's Twin Reverbs I've read.
Obviously these amps suffer greatly in the pre-amp area but for my home/never gig out use it's just fine and I plan to keep it for awhile. I do pine for some tube/spring reverb however.
I still plan on replacing the power multicap again keeping all the original parts with the amp. I'll update when I get there. Thanks again guys(especially bluesbear).

[lowatter]

I ordered some German F&T power caps that are due in this week and after I re-cap I'll give an update of how it sounds then. I'd like to know that it's sounding the best it can to sell locally so I can get a Blues Jr for the reverb. It's going to be a tough decision because this amp sounds incredible with a mult-effects in front of it and I may end up just getting a Holy Grail or other analog reverb to put in front of it. Any recommendations guys?

[bigdaddy]

I have an interesting idea. How about making this amp a champ amp but with paralleled power tubes.

Disconnect the PI transformer and add a .022 cap, grounded 220k resistor and a 1.5K screen resistor. Hook it all up the same as a champ amp but parallel the power tubes. You could probably use the same OT just eliminate the middle wire. It's better to probably use a Hammond SE 10 watt OT at 2.5K primary for this setup. Find the correct bias resistor. Not much work to do.....and you don't have to hack the amp apart. If you use the Hammond it's a matter of making an extra hole to mount it.

You could also make a tone stack easily by moving the volume control to the second input and using the volume/tone controls as a treble mid with either a typical Fender or Baxandall tone stack.

This setup will probably give you about 10 watts. I had a few of those Blackheart amps with an EL-84 and they were pretty loud with a speaker like a celestion Blue. An amp with 2 would really push a higher efficiency 12 like a blue or red fang or any other emi speaker which all have very high SPL levels and sound great.

I have had blues juniors and I think this setup would sound a lot better. The blues junior reverb is solid state anyway and a reverb pedal would probably sound better then anything the blues junior would give you. Also blues Jr.s are dark sound and I never liked the tone no matter what I did to it.

[fenderboy]

I picked up a Musicmaster Bass amp in the mid 90's.  I found one in a pawn shop for $100.  I had a Champ which wasn't enough. The transformer phase inverter was unique.  And push pull on the cathode biased power tubes took me back to the old Princeton I once had.  I won't mod a blackface or earlier, but for me certain silverfaces are open game.  Sorry if that offends some.  You can always put them back to stock.  I don't like tone controls.  I was stuck with them too much in the 60's.  I changed my musicmaster to a standard Fender front end with a 1meg volume, 250K treble and 250K bass control between V1A and V1B.  I didn't desecrate the faceplate, I made a new one.  Also, I prefer 6V6's, and took out the 6AQ5's.  With the volume control stacked on the top of the on/off switch, I had to carefully disassemble and change the resistor plate in the volume control from 250K to 1meg.  That is the only way it will work.  The amp has more bass than I want now.  My wife's Gibson 339 sounds real good through it, as it is a bit of a bright guitar.  I can send you the schematic for this if you want.