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New DIY modular bass amp

Posted: Thu May 14, 2015 12:17 pm
by Emperor-TK
I'm approaching the finish of my DIY modular bass amp and I thought that some here might be interested in the project (if not here, then where else? ;) )

At first, I was just going to use an RM4 with a big solid state power amp, but I really wanted a couple of features that rig couldn't provide. That combo was too big, actually being wider than my 18" wide bass cabinet. Also, I would never need four modules for bass, but I wanted to use dual channel modules. This led me to whip up the following amp.

The amp uses a pretty typical RM4 type front end with a few minor changes. I don't really care for the switching on my MOD50, with a switch for each channel. Instead, I wanted A/B switches, one for the module, and one for the channel. Now I can use only a dual footswitch to control a double module dual channel amp. I don't need midi on the amp, so I went with basic relay switching for the logic signals to the modules. The relays are controlled by a programmable logic chip using momentary switches to change states. This way I could have redundant switches on the front of the amp and on a foot pedal like the original.

For the power amp, I went with a 500W ICEpower/Bang and Olufsen Class D amp that has been showing up in a bunch of commercial products these days. I used the 200W version in another build, and I'm pretty happy with the performance.

There's still a couple things left to do. I need to upgrade my 12V transformer because I ran out of juice (hence the lack of tubes in module 2). I have one on order that has roughly the same footprint. I also want to add a DI out and a built in tuner. The three LED holes on the front are for the tuner, and I have a relay installed to switch the input signal between the tuner and amp. I hacked up an old Sabine and it works, but the clock is injecting digital noise into the circuit that I need to suss out. I removed it from the amp in the mean time.

Anyway, I used it at rehearsal last night, but the Vox module doesn't have quite enough low end for me. Bass-centric modules are next on my list, starting with the Fender Dual-Showman/Alembic F2B circuit that I used in my last build. That sucker has a nice fat low end.

For years I used a '73 Marshall as my bass amp, sometimes with an extra Ampeg V4B to round out the bottom. I plan on doing some bass modules for myself based on guitar amps, but with blend knobs to blend in the clean sound for deeper lows. However, the one thing that everyone gets wrong with blend knobs on bass overdrives IMHO is that they blend in the full frequency clean sound. This never sounds good to me. It's a clean sound disconnected from an unrelated over-driven sound. I'm going to do a low pass clean sound for the blend so that the clean just fattens up the overdrive a bit without adding any real timbre to it.


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Posted: Thu May 14, 2015 2:17 pm
by Emperor-TK
Fixed my broken picture links, I think.

Posted: Thu May 14, 2015 3:06 pm
by MarcoR
Yes, the pics work now.

That is ridiculously killer!!! I wish I had the skill to do that...

Great job man!!

Posted: Fri May 15, 2015 3:37 am
by goldtop
Excellent work, Emp! Bookmarked to come back and pore over later! :)

Posted: Tue Jun 28, 2016 5:52 am
by JackTheLad
1) This is awesome! Great job!
2) could you please explain where did you find the connectors where the modules goes in and how did you make it capable of using dual channel mods?

Edit: Just noticed that I already posted here ->
http://mtsforum.grailtone.com/viewtopic.php?t=20898

Posted: Tue Jun 28, 2016 7:26 am
by Mattfig
Holy s*&t is that cool! Great work Emperor!

Posted: Tue Jun 28, 2016 12:42 pm
by JKD
WOW is all I got...great work!

Posted: Wed Aug 03, 2016 12:26 am
by CrazyNutz
Rad. Great work

Posted: Thu Sep 22, 2016 1:03 pm
by djdayson
Awesome, nice DIV job!

What did you use for your card slots? We found surplus crap at a local junk store and cut up project boxes as supports, though yours are beautiful LOL!

Here's our DIY 50W RM2 featuring two MTS preamps (currently single-channel), a 50W Class A solid state power amp, a Two Notes Torpedo CAB providing tube power amp sims (replacing a loaded 1/4 W 12AU7 power amp), room sim/reverb, cabs sims and EQ (plus the Axe FX Ultra for FX and mixing/switching of the preamps).

The RM2 also features the RM20/22's pre tube boost stage.

Image

Posted: Thu Sep 22, 2016 1:26 pm
by withmittens
Hey! The E2 finally came out through the back door.

Posted: Thu Sep 22, 2016 1:37 pm
by djdayson
Are they shipping?
withmittens wrote:Hey! The E2 finally came out through the back door.

Posted: Thu Sep 22, 2016 1:41 pm
by withmittens
djdayson wrote:Are they shipping?
withmittens wrote:Hey! The E2 finally came out through the back door.
I Bet Emperor-TK could beat Synergy to market :lol: :lol: :lol:

Re: New DIY modular bass amp

Posted: Thu Nov 24, 2016 4:40 pm
by ramalhais
Emperor-TK wrote:I'm approaching the finish of my DIY modular bass amp and I thought that some here might be interested in the project (if not here, then where else? ;) )

At first, I was just going to use an RM4 with a big solid state power amp, but I really wanted a couple of features that rig couldn't provide. That combo was too big, actually being wider than my 18" wide bass cabinet. Also, I would never need four modules for bass, but I wanted to use dual channel modules. This led me to whip up the following amp.

The amp uses a pretty typical RM4 type front end with a few minor changes. I don't really care for the switching on my MOD50, with a switch for each channel. Instead, I wanted A/B switches, one for the module, and one for the channel. Now I can use only a dual footswitch to control a double module dual channel amp. I don't need midi on the amp, so I went with basic relay switching for the logic signals to the modules. The relays are controlled by a programmable logic chip using momentary switches to change states. This way I could have redundant switches on the front of the amp and on a foot pedal like the original.

For the power amp, I went with a 500W ICEpower/Bang and Olufsen Class D amp that has been showing up in a bunch of commercial products these days. I used the 200W version in another build, and I'm pretty happy with the performance.

There's still a couple things left to do. I need to upgrade my 12V transformer because I ran out of juice (hence the lack of tubes in module 2). I have one on order that has roughly the same footprint. I also want to add a DI out and a built in tuner. The three LED holes on the front are for the tuner, and I have a relay installed to switch the input signal between the tuner and amp. I hacked up an old Sabine and it works, but the clock is injecting digital noise into the circuit that I need to suss out. I removed it from the amp in the mean time.

Anyway, I used it at rehearsal last night, but the Vox module doesn't have quite enough low end for me. Bass-centric modules are next on my list, starting with the Fender Dual-Showman/Alembic F2B circuit that I used in my last build. That sucker has a nice fat low end.

For years I used a '73 Marshall as my bass amp, sometimes with an extra Ampeg V4B to round out the bottom. I plan on doing some bass modules for myself based on guitar amps, but with blend knobs to blend in the clean sound for deeper lows. However, the one thing that everyone gets wrong with blend knobs on bass overdrives IMHO is that they blend in the full frequency clean sound. This never sounds good to me. It's a clean sound disconnected from an unrelated over-driven sound. I'm going to do a low pass clean sound for the blend so that the clean just fattens up the overdrive a bit without adding any real timbre to it.
That's excellent work! I've always wanted to do a DIY modular preamp, but didn't have preserverance :P
Roughly, how long did it took from the initial idea to the finished work?
Congratulations!

Posted: Thu Apr 20, 2017 3:39 pm
by lightwoheat
Emperor-TK, Nice work!
Did you have to custom make the PCB slot holder or where you able to buy the metal pre-made and add the plastic pcb slot to it?

FM

Re: New DIY modular bass amp

Posted: Fri Jul 05, 2019 5:06 am
by jdel77
Outstanding.
This should totally be a commercially available amp.