18watt: A forum dedicated to Marshall 18 watt amps butvery friendly and informative about building amps in general.
Ampage: Guitar Amp Forums
Sewatt.com : forum about single ended tube amplifiers (with just one power tube)
Amp Garage: Discussion and schematics of Trainwreck and Dumble amps
Amptone.com an exhaustive ressource about amp technology
Duncan Amp: Tube data, tube amp schematic links & software like Tone Stack Calculator etc
Fender Amp Field Guide: the tube amp lover's bible:...
I'm currently in the process of working on a diy Sloclone 50 Tube amp build, it is basically a 50W Soldano SLO, but, I'm planning on using a pair of matched JJ KT77 power tubes instead of 5881 tubes as used in the original SLO 100, I've never tried KT77 tubes before, apparently from what I've read online, they are like a cross between the EL34 and the 6L6, and are supposed to be a drop-in replacement for the EL34, a mate of mine said that KT77 tubes should be a nice choice for...
Hi all, I’m restoring an old tube record player (mono) the tone control is positioned after the pentode. Does anyone know why it would be there?
I’m thinking of moving it after pre amp,
Has anyone else noticed this new amp recently? I spotted it on ebay about a month ago and now there are sound samples. I just ordered one from a seller on Reverb for $155 with free shipping. I plan to swap out the stock Chinese tubes with (2) Tung-Sol 12AX7 and (1) JJ ECC82 tubes. I will be reverse engineering this pcb and making a schematic. I want to modify this amp!
POWER: 1WATT ALL TUBE
PRE-AMP TUBES: 1.5 (3 stages)12AX7/ECC83
POWER AMP TUBES: 0.5 (1 stage) 12AX7/ECC83 and (1) 12AU7/ECC82...
Just got a Fender 75 amp. I've spent two whole working days restoring it to factory specs. To make future easier for someone, here are layouts - of a Riviera-Era footswitch (which works for all Riviera-era amps, see and of a Hi/Lo and Standby switches in a 75.
A while ago, the you-tube algorithm started feeding me videos from Mend-It Mark, a general electronics repair guy of the archetype that I thought had all but disappeared years ago, even though he looks a bit younger than me.
I got quite into watching the videos of his repairs when they pop up in my feed, mainly for the debugging patter, where he clearly explains his logical process in chasing down faults (all sorts of different devices, but occasionally audio stuff, amps or guitar fx,...
Well, I just had two more of these abortions in my workshop - both with that nasty buzz/ hum ;)
I tried increasing the capacitor at the input of the 10v regulator but unfortunately the buzz was still there, although reduced slightly, SO, i decided to find out what exactly is wrong with these poorly designed amplifiers and discovered some very interesting crazy design faults.
First : The grounding scheme for these amplifiers is disgusting ! The amplifier...
It's cute and pink and it's probably a accordion amp, but got kind of intrigued by the tube setup:
1 x 12AX7 or ECC83
2 x ECL82 - which is a triode and pentode in one package!
3 tubes: 2 gain stages, tremolo, phase inverter and 10W output
Earlier this year I had the good fortune to buy a mid 70's (I'm guessing) Fender Super Twin amplifier chassis that was installed in a wooden cabinet for a Blackface Fender Bassman, I'm planning on doing some restoration work on it to firstly make it safe and also to get it working at it's best, although the guy I bought it from said that it does work, I'm also planning on building 4 X 10 or 4 X 12 speaker cab for it, here's a pic of the Fender Super Twin sitting on top of my Marshall amp:
I need a bit of advice and guidance from the valve (tube) gurus.
I’ve been fixing valve gear since before solid state was available (mid 60’s) and have built a load of SS amps and even one class D but never a valve amp.
I recently discovered I had an old push pull output transformer (marked P4133, possibly an early Partridge P4133, probably late 50's or early 60's).
I also have a couple of suitable looking mains transformers (250v @ 60mA + 6.3v @ 3A and 260 – 0 – 260v current unspecified...
Blue stripe peavey bandit 112...it's a weird amp with weird controls for sure but the issue is on the clean channel, using the left most pot as volume,it can't be turned up last 1. Doing so increased the volume to 1million percent. Insanely loud and unusable. After cleaning all pots and jacks with contact spray, the problem persists and is now present on the distortion channel. Prior to cleaning the post gain on the distortion channel could be turned all the way up and not be super loud now...
It's been a while since I tinkering with something, so yesterday I started breadboarding the preamp section of Roland JC-77. All tone control works as expected, Distortion works but there's some unexpected behaviour coming from distortion part.. The clean are very low compared with the distortion.. There's big jump on volume between clean and max distortion.
I'm also not really sure on the footswitch arrangement.. If I want to remove footswitch feature, then I can just connect...
Hi there, I'm restoring a guyatone ga-960 black5. So far so good. The problem is that the reverb volume is as loud as the volume coming through each channel. The reverb signal also sounds like it is getting all the frequencies that are going through the channel. I figured the input capacitor may be blown 500pf, but then that would also leak hum from the b voltage......I can post a schematic. Just wondered if anyone had thoughts or had experienced this. It is from the early sixties, maybe this...
First time posting, and just curious if anyone had any helpful advice for lowering the noise floor on some preamp projects...
I've been interested in those cheap class D power amps for a little while, and have run my HX stomp (just running a preamp model) into these class D power amps into a guitar cab with decent success (and a very acceptable noise floor on even high gain amps).
With that in mind, I've been trying to recreate some of my favorite tones in the analog world using...
Good day L & G,
I was looking for suitable candidate for my bench amp and I found schematic of Roland Jazz Chorus JC-20 from this japanese website :
Looks like this is the one and only JC-20 schematic on the interweb. Anyway, from his article, I got impression that the guy who trace it are surprised that this kind of circuit are released into final products, so probably there's something weird into this circuit.
I did my research based on several another article & gutshot pictures of the...
I am trying to fix a Fender practice am with a loud hum noise.
the amp works but it has a hum noise (50hz) loud even when the guitar is unplugged.
- Volume, Contour, Reverb doesn't affect the noise.
I had attached the schematic for the amp Fender R.A.D. that is the same without the reverb circuit.
I tried to connect the preamp output to another amp and the noise still there. My first thought the issue is in the power supply I changed all the electrolytic capacitors in the...
This beloved amp is getting old or tired of my playing.
Plugging in into High Input and turning preamp pot from 8 to 10 behaves weirdly
loud squeal if cable is plugged in without an instrument;
with single coils middle pickup squeals and with bridge or neck pickup it has harsh sound when distorting;
with single coils turning down the tones remove the squeal;
With humbuckers there is no squeal at all;
Power tubes have been already replaced with matched EL34, bias 8uf caps replaced....
I want to use two 12 volt filament transformers back to back followed by a voltage doubler to power a marshall style tube preamp. The voltage doubler is a full wave bridge rectifier with two of the diodes replaced with two capacitors. (You all probably allready know this.) My question is how large and what voltage should the capacators be? I haven't found many schematics on this but the ones I've found range from 10uf to 330uf. I'm using two 12ax7s. The voltage doubler is converting 120 volts...
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum