Marshall Based Conversions

I started doing these conversions to build a great value amp that did not skimp on robust design, great tone and classic or modified circuits that folks could try without breaking the bank. Many of these amps are standard offerings I now sell regularly on Ebay but are also available anytime- just drop me an email at frugalamps@gmail.com

Here are just some of the many dozens of these I have built. If its something I usually make or have on hand, I have noted the price shipped in the lower 48.

This is a Hammond Organ amp convered to a Marshall Lite IIb circuit. Think of it as the essence of a Marshall with great clean tone, wonderful crunch and overdrive, 18 watts of tube power. I build mine with a master volume control as well. Uses 2 12ax7 preamp tubes, two EL84 power tubes, cathode biased so tube swapping requires no bias reset with a multimeter or trip to the amp tech. This one has a tube rectifier but they can also be built with solid state diodes. These are $390 shipped.

 

 

 

 

This is the inside. I layout all these amps pretty much the same. I use a tag board construction for the majority of the components. I use isolated input jacks grounded with the preamp section and tone controls for a quiet amp. The wiring runs are super short and very quiet as well. For the Marshall circuits I like the mallory capacitors. Alpha pots, switchcraft jacks, Carling switches. The output transformers are 8 ohm and very good sounding. Hammond made and still makes great transformers. I really feel at this price for a handwired tube amp it is a hard deal to beat. But then, I am blowing my own horn a bit. After selling many of these however, most owners agree. Your getting a new amp built in a vintage chassis and vintage transformers.

 

 

 

 

Color choices are popular. This one was requested in a copper hammertone. Frankly, I do not spend a lot of time making these look really pretty. I spend all the effort getting them sounding good and leave the cabinet, mounting board or whatever they wind up in to the customer. I learned long ago that woodworking was not a strong suit for me. These amps have mounting tabs on each end predrilled with hole to screw down to a board with some feet or you can go to Home Depot and get a sheet of aluminum or steel and cut it to cover the bottom, attach some feet and sit it on top of your speaker cabinet or table top. They measure 12.5" by 6.25" with 5/8" mounting tabs on each end. Total length 13.75". The chassis is 2" tall and with tubes its 5" high overall.

 

 

 

This is a 9" by 5" organ chassis that I build an 18 watt Lite circuit into. Yep, it all fits in there and will blow you and your friends away with what comes out of this little guy. Puts a Fender Blues Jr. to shame. I have to delete the master volume and the standby switch that come in the bigger conversions but aside from that, its a huge sound from a little guy. These are $295 shipped to the lower 48.

 

 

 

Here is the inside. I build a small eyelet board for the preamp and go point to point with several components right off the input jacks or the volume pot. Wiring is short, sound is huge.

 

 

 

 

 

 

And not to ignore the backside, here is the 8 ohm output tab- same size output transformer as the larger amp, so great bass response.

 

 

 

This is a variation on the 18 watt amp. It uses an EF86 preamp tube in the first spot then another 12ax7 and the 18 watt Marshall power circuit and tube layout. The EF86 gives this amp a whole different sparkle and drive dimension. I have had guys tell me this is one of the best amps they have ever played. I will submit they are like a cross between a Vox and a Marshall. The EF86 tube has a huge output compared to a 12ax7 and they can be fussy and go microphonic but when they are singing, they sound great. I always recommend a backup EF86 if you are going to gig with this preamp setup- no different than an EF86 based amp however.

These amps are $390 shipped to the lower 48.

 

 

 

The insides of these amps are very similar to the regular Marshall Lite. There are a few component changes and the wiring to the EF86 is totally different than a 12ax7 type tube. I have tried a lot of tweaks to the values and arrived at what I hear as the best in terms of clarity, overdrive and tone.

 

 

 

Here is another conversion with a high gain twist. This amp has a hot rodded preamp section with a unique gain adjustment that can be controled from the front side of the amp with that first gain knob in the picture. This is similar to how Dumble built his amps with an adjustable preamp gain pot on the circuit board- I just brought this one out front. You have to be careful, a little turn and the gain really comes on. Same tube setup and power section as the regular 18 watt Marshall based amps. These amps are $425 shipped.

 

 

 

 

 

This is a look inside. I have tried to standardize a lot of the layouts of these conversions to keep the prices I have to charge down. As more hobbyists begin to build amps the cost of the original donor amp has kept going up. I may have to switch to all new components someday but these amps with the vintage power and output transformers just sound so great, I hate to change if I don't have to.