pix of Custom built guitar amps/cabs

[davent]

Hi Chris,

Great job! Finished just in time to go back to school. Do the silicon rings on the Ef86 make a big difference in taming the microphonics, did you try anything else to help reduce the chance's of ringing, suspend the socket, grommet the socket etc.?

Take care
dave

[kurtlives]

Hi Chris,

Great job! Finished just in time to go back to school. Do the silicon rings on the Ef86 make a big difference in taming the microphonics, did you try anything else to help reduce the chance's of ringing, suspend the socket, grommet the socket etc.?

Take care
dave

Thanks Dave,

Done just in time. Had the amp done for a while now tbh, cabs are always the thing that holds me back.

From my research EF86 are very prone to becoming microphonic, especially new production (apparently they are garbage). Anyways I got a NOS Aprex in their now. I am not sure how much the O-rings are doing, as the amp is very stable right now. Maybe with it being in a head now and on top of a cab the tube might see a bit more wear and tear.

[kurtlives]

Good stuff. Trinity kit right?

Jacob

Not a kit, chassis, OT, PT and board (later modified) from Trinity.

[davent]

Hello,

Been messing about with this one for quite awhile now, another little girlie stupid over-the-top two tube single ended perfboard/pcb/eyelet board/strip terminal/p2p handwired amp to use up a couple odd tubes in my possession that didn't have a homes. Based on Dave Jones' Octal One which in turn was a twist on the Fender 5c1 circuit (6sj7/6v6), i'm using a 6aq5 (7 pins) instead of the octal power tube (based on Wattkins' Savage Croaker).

Little (too little?) Hammond  262F6 PT and an Edcor XSE 10-8-5k OT. Hammond 5 x 7 x 2"  chassis.

Used a voltage doubler with 120Vac to get the HV.

Used the power scaling circuit to limit the HV to ~ 10Vdc - 270Vdc.

Regulated the preamp HV so it always remains the same when the power scaling is adjusted.

Playing around with various preamp components seeing how they effect the ultimate tone.

Tried a squish control on the 6sj7 but for me all it was doing was rolling off high end and quietening the amp too much so will wire some sort of tone control into the squish control spot once i'm happy with the naked sound of the amp.

Have made a few small deviations from the savage croaker values around the 6aq5, will play with that more once i'm settled with the preamp.

Elevated heaters @ ~75Vdc with voltage divider from the preamp HV.

RFI filter on the mains.

Lots of fun to play, really nice tone,  very pedal friendly, really quiet functioning, not ear damaging loud to play until you hit the front end with a pedal. Favourite pedal with it so far is a SHO. If you like how your guitar sounds the SHO gives you more... way more if you want, can absolutely hammer your preamp with what is to me an uncoloured output.

One niggling issue so far,  the power transformer will start to buzz loudly after playing maybe 10 minutes with everything full up. Doesn't seem to have any effect on the sonic output but is annoying. Taking voltage and current readings throughout the amp doesn't turn up any obvious anomalies so i'm wondering if i've got the PT pushed past it's comfort zone. It's rated as a 26VA and plugging the amp into a Kill-a-watt meter shows the amp at pretty close to that level of power usage. The PT doesn't get outrageously hot (infrared thermometer) when compared to other PT's in other amps -  just starts to buzz.

Original intent for the cab  (11 x 6 x 6") was to try to do something similar looking to an oldtime Bakelite radio, bought some nice Seafoam green upholstery vinyl and a bunch chickenhead knobs in various colours to try to get there.  Always liked that bare, Baltic birch, minimalist Ikea look and once i'd finished getting the cab ready to cover really didn't want to hide the wood so slapped  some waterbased satin Varathane on instead to protect and highlight the plywood.

SHO

 

dave

[deadastronaut]

@dave..

that is simply lovely...love the retro look of it...cool

[Cap]

..Amazing...

[jkokura]

Wow! I'd love it if you shared plans on how you built that Cab! I love the style of the front! I wonder what it would be like to use a wood burning kit (you know, the ones you had when you were a kid) to create labeling for the knobs...

Jacob

[kurtlives]

Very nice Dave, your build style is so unique and just amazing.

I remember on Amp Garage a month or two back a guy was having issues with a Heyboer PT buzzing in his Express. Can't find the topic now, or remember the solution but your problem doesn't seem to be unique.

Would love to see  a schem if you have one.

[davent]

Thank you for the kind words guys!

Little (too little?) Hammond  262F6 PT and an Edcor XSE 10-8-5k OT. Hammond 5 x 7 x 2"  chassis.

Can't edit the original post, the chassis is 9x5x2" .

Jacob i didn't really have a plan per se, just some sketches that i did in TurboCAD to grab measurements from and try out ideas. Are you interested in the actual cab dimensions, construction details,  the front/back panel layouts, developing a plan/layout? 

Personally i wouldn't do the woodburning as my handwriting/printing is pretty miserable at best and i know i'd never be happy with my results (plus it's only three controls so no big deal to keep track of). But of course it is doable for those with the knack and tools. Also over at ampgarage someone was using a laser to label and put an emblem on faceplates for the Trainwreck clones people were building, same principal , a bit more 21st century.

Chris as it stands  these are the schematics. The pre/power amps are evolving, the power supply is static (but if i decide on a bigger PT will ditch the doubler for the more conventional and do a new pcb).  The preamp regulator came from a manufacturer's post at diyaudio and is what he was using in his phono preamp so is way overkill for a guitar amp but does what i want (and very quietly). The VVR and LP's Powerscaling circuits start out much the same but differ in how things are handle after the Mosfet. R4 is not part of either circuit so the raw b+ is connected to the mosfet drain and top of the 1M pot. I needed to loose a bunch of voltage because the 6aq5 max. plate spec. is 275v . Calculated a voltage divider based on the raw B+ into and 270v out of the scaling circuit, the lower leg of the divider being the pot's 1M plus R2, 47k, 200k was close enough.

R5 is not on the pre regulator pcb, it was there to be a bleeder. It now parallels C6 on the amp schematic, located on the bottom of the eyelet board.

One of the options i'm looking at for a tonestack is the Matchless coupling cap switch like in your amp. What are your impressions of that arragement?  Right now this amp is a bit on the dark side and am trying different things to brighten it up.

dave

[Ronsonic]

Dave, that is just a great look you've got there. Sweet.

[kurtlives]

One of the options i'm looking at for a tonestack is the Matchless coupling cap switch like in your amp. What are your impressions of that arragement?  Right now this amp is a bit on the dark side and am trying different things to brighten it up.

dave

Thanks for the schems. Always interesting to see how others are building/designing things.

Got to ask though...whats the purpose of the resistor across the OT's secondary? Protection, altering Z?
Your making me want to build one of these small classy amps!

The rotary switch "varitone" controls works quite well. It works even better for pentodes (which I see your using). Because of the output Z of pentodes they aren't very good at efficiently driving tonestacks. So the varitone method works, it's simple, lots of tonal options, less real estate and interfaces easily.

I personally like it, it's very easy me to dial in a tone. You can always change cap values to suit your taste.


Btw if you want to brighten the amp you might consider a small ceramic cap across the volume pot (22pF - 100pF).
Another thing I found with a recent build of mine is increasing the screen voltage on pentode preamp stages can really bring a stage to life. On my EF86 amp I had a 2M2 screen resistor like you, around 80V on the screens. Dropped it to 1M, 130V on screens. Amp became more lively, responsive with more feel and compression. Just throwing it out there cause I rarely hear it talked about and had a good personal experience.



Sorry for slow response, got busy....

[davent]

Hi Chris,

The 270 (2watt in this case) is a borrowed idea from TUT, it's always shown on their guitar amp schematics and is there to protect the OT.

Thanks for the pentode ideas, i can play around with most of those values but am going to have to go shopping for some ceramic caps. I have played with the screen resistor value (as well as the cap) taking it down to 1M1 but just to take voltage readings. With the 2M2 the screen's at ~19v (plate at 137v) then with the 1M1 the screen rose to ~30v and the plate dropped to ~86v. Didn't give it a listen at the time i was just interested in seeing how voltages were affected messing with the various screen resistor values. Cathode voltage also rose as the screen resistance was decreased.

I've got lots of coupling cap values on hand so next up is sampling them to see what kind of varitone i can put together.

There seem to be alot of little two tube circuits out there to sample. I'm thinking of using the other set of transfomers i've got to do a breadboard set up so i can easily play around with a bunch of different circuits before committing to one circuit and one set of tubes. I'm enjoying playing around with these little amps, if nothing else they're a little easier on the hearing... always need to hear just how loud an amp can play and once it gets there it's hard to turn it back down.


Take care
dave

[Top Top]

Amp I built in a sweet looking old space heater.



It's 10W solid state...

[deadastronaut]

@toptop...love it...very retro...sweet.

[p_wats]

Hey guys,

I just finished building my first amp. It's basically a Princeton 5F2-A, but I used mostly recycled parts from old radios that my friend/amp guru had. The PT isn't as powerful as an actual Princeton (only about 280V for B+), but it still sounds great! The OT is from musicalpowersupplies.com and I can't stress how happy I was with Matt's service and patience.

Other than that the mods are minimal: SS rectifier and added a switch to toggle the negative feedback in or out.

The chassis is from an old radio and it's pretty small, so space is tight (and wiring is ugly):







The cab used to be half of a turntable w/speaker combo that I painted (front is all original except for the button I put on to cover a whole where the speaker used to connect to the turntable) and it's loaded with a vintage 8" speaker my friend had (chosen for it's small magnet, so it could all fit nicely in this tight package.







All in all I'm really happy with it. I learned a hell of a lot building this amp (made a lot of mistakes along the way too). It sounds great, is really small and light, and cranks through an extension cab.

Woo!

Paul

[Top Top]

That looks really nice Paul.

Whenever I can get over my fear of wall AC, and of spending money on transformers, I'd like to build a tube amp.

[p_wats]

That looks really nice Paul.

Whenever I can get over my fear of wall AC, and of spending money on transformers, I'd like to build a tube amp.

Thanks! I got lucky with parts, as I recently befriended a guy who repairs tube radios and builds amps. He's collected a massive amount of parts, so I got my power transformer from him and the output tranny was only $19.99 from musicalpowersupplies.com.

All told this baby only cost my about $150-200. Of course, a lot of the parts were salvaged (chassis, cab, speaker...).

[moisho]

Here is mine:

It's a single ended point to point, almost totally recycled (frame is an old reverb tank). It has around 2'5 W, pentode/triode selector, kind of jazz mode and full tone stack.



By the way, meet Nahia, the future owner, supervising everything!!!



this is the initial idea:



Tolexing (this is my first one... next one will be better):

 

...Head almost finished:



And the final results:

 

[Ronsonic]

That cleaned up nice!!!!

[anchovie]

My new baby - its ugliness is its charm:



Marshall 1987 preamp into a pair of 6L6GCs. Components are all mounted on perfboard. Transformers and choke were aquired dirt-cheap as a set from a guy who was shutting up shop and clearing out his stock. Chassis was a half-price second because it was marked (I knew I'd make far more marks of my own so that wasn't a worry!). Headshell involved my first ever use of a hand-held jigsaw and a 4U rack case that I wasn't using. Stickers from Poundland.

Total outlay approximately £180. Sounds like dirty glass and takes pedals brilliantly. I'm very, very happy with it!