Thanks Phil, he said with a shake of his head... 8|
Just when my world is going through major upheaval, other half retiring in 6 weeks, trying to get ready for a move of a couple hundred miles back to where we tied the knot thirty mumble years ago, getting the workbench stuff packed up for moving as well as a household that has accumulated an incredible amount of "stuff" over the last couple of decades here in the great state of Taxes, and now you come up with something that begs to be built.

Looks very nice, just don't know when I will be able to get to it. I just can't let a certain bass playing friend see this or I won't get any peace until he has one tailored to his needs.

You identified your number 1, the rest are the various transformers that make these old amps wiegh a ton.

In order as you have them numbered,

2: Reverb transformer for coupeling to reverb unit.
3: Output transformer - on one side couples plate voltage to the 6v6 plates, the other side talks to the speaker.
4: Power supply filter choke. More ripple and transient cleanup for the DC side of things.
5: Power transformer - takes that nasty real world AC voltage and turns it loose inside your amp.

And to repeat what others have said, definitely change the power supply and bias caps. The cathode bypass electros (the white 25v 25uf polarized parts) will probably need it, one of the signs of a bad bypass cap is motorboating, but when their value changes, so will the frequency response of that stage, so that some frequencies will be amplified more than others. This changed sound may be desirable, or otherwise. Your ears will have to decide on that one, but any motorboating, just change them all. They are not expensive and the amp will thank you for it. The other caps will hardly ever go bad, although I did have a ceramic disc break a leg on one of my Bandmasters trem circuit.

All told, you could recap it, doing it yourself, for $40. And learn a bit about the design while doing so. Have fun, and respect those DC voltages. You will have somewhere north of the 420vDC the circuit originally called for depending on how much your house current varies from the old 110/220 vAC standard. Measure carefully, and use the old tech standby, keep your left hand in your hip pocket.

Quote from: Tobyguitaramps on February 14, 2014, 01:22:59 PM
Hey bobhill i know its the wrong place but is there any way i can a scmatic on that toby amp :dbtu:

pm sent

Thanks, Dr G. Much easier to read.

Roly, I was introduced to Arnott's when I spent a couple of weeks in the Siding Spring - Coonabarabran region doing astronomy a few years back. Since, I've found that Costco/World Market in the states actually imports them. I would rather they imported the very tasty Brothers in Arms Shiraz I was also introduced to that trip, but at least the vegemite display is very small. :cheesy:

Can I look properly abashed? I will blame it on my laziness on not searching for a readable copy of the schematic. I had noticed the protection diodes, but not having things legible, I assumed (there is THAT word again) that we were not talking about these, as they are not clippers. My response was from seeing the circuit, but not values, around U2b, the "timmy" clipping arrangement. I think that when the OP talked about clippers, we all automatically zoomed into the clipping stage of the pre amp. I did. Sorry. Grumble grumble. No cookies (biscuits) and milk tonite... No Arnott's for me.

Looking at the schematic from Fender.com for this amp, it already uses a form of soft clipping. If you look at the clipping stage (looks to be the first half of the second tl072 in the signal path, kinda hard to tell with the blur filter fender seems to have for this pdf), that is the method of clipping used in the Timmy pedal, with a pair of leds substituted for the second pair of diodes. The resister before the junction between the diodes and leds increases the soft knee characteristic turn on of the leds. All the pair of diodes are doing is to raise the clipping threshold by .6vdc, giving you a clip point of approximately 4.4vdc p/p. Having scoped more than a couple of these circuits, the waveshape is a soft turn on. I will leave it to those who are busier arguing about it than playing as to if this style of clipping is more "valve/tube" like, or not. Be that as it may, the only thing that would be accomplished by removing D1&2 is to lower the clipping threshold, pushing things to the square wave distortion point that much earlier. And make your output signal 33% quieter.

The caveat in all this is how much gain previous preamp stages have given the signal, and how close the signal peaks come to the power rails. Again, thanks to the Fender blur filter, this is rather hard to calculate.

The main point to take from this, is that the amp is doing the job it is designed for. It's problems come from inadequate cabinet size for the speaker. The speaker itself is not the worst I have ever seen, but it is crippled by the cabinet. I have seen some folks kind of tame the ice pick from these by using a Jensen Mod 10 to replace the stock speaker. Your mileage may vary, and like clipping diodes, most of what you hear on the internet about speakers needs to be taken with a very large grain of salt.

And by the way? Those "hard" clipping diodes? The tubescreamer uses three of them in pretty much the same configuration to produce it's sound. Only difference is the crappy op-amp used in the TS. If your fender was using the same JRC4558 that the TS used, I could see changing them out. The magic in the 4558? They cost Maxon and Ibanez $0.012 each. The Fender uses TL072's which are just fine. And depending on your soldering skills, none of the op-amps are socketed, and these traces lift up awful easily.

The folks above gave you some very good advise, and they do know what they are doing and have been doing it for many decades. That is what is neat about this place, no BS and folks that have been there.

I have a pair of the dsp versions of the Champion 30, one from 03 and the other 04, and I have found them do be very dependent on the room they are in as far as their noise output. Their power line filtering is not very strong, any room with dimmers on the lights will cause them to complain, not much better with florescents. The dirt channel amplifies whatever noise is in the environment, so I guess it's a good thing all I use are the clean channels. That is the main negative I've found about these amps.

On the other side, at home in my computer room where I use them to test pedals and other "quiet" playing, these things are great. I have plugged everything I have into them, run them in stereo, experimented with cheaper guitar and pickup combinations, and found them very pleasing to these old ears. And very noise free in a room with computers, tv, wireless router, you name it. Quiet with cs69's in my strat, with the 492/498's in the LP studio, the whatever they spec'd for the PRS SE hollowbody, the Ibanez acoustic piezo's, just quiet amps with all my guitars. Although I do not recommend plugging a bass into them. The 10" can get a bit flubby when you get serious on the bass. The other occasion when the stock speaker can get a bit flubby is with some external modulation pedals. Extreme settings on the pedals will cause the bass response to complain. Not enough speaker to move the required amount of air. External distortion/od they like just fine.  They can get bright, but the onboard eq can and does keep the icepick under control.

I have played with mine for several years now, they are great for their capabilities, loud enough with 30 watts (actually spec'd for 27.5, but marketing...) for some jamming/gigging, and one hell of a lot easier for these 66 year old bones to haul around then the full stack superlead I was hauling in the 70's. Or the pair of blackface Bandmasters I currently try not to move very often.

I like them, but as always, your needs, ears etc. etc. YMMV LSMFT I can be held to no opinions expressed or implied. Very decent good sounding lightweight small combo's that can be found very cheaply.

Simplest way to figure out what you have is to swap the tube positions. See if the changes follow the tube or the socket. (Ignore NA bias for those of you who have valves in your amps )

This appears to be the same station I got from CSI a couple years ago. Even at the price I paid (somewhere around $40) , it has been an excellent solder station. No, it is not an industrial Weller, but for the home / hobbiest it is a lot better than the Radio Shack stuff. I've only done a couple thousand or so joints with it so far, the tip is as shiny and sharp as the day I got it, so tip wear seems minimal, but I do keep it clean. It comes with another ceramic heating element that I haven't done anything with except try to store it somewhere I might remember.

As long as it is used for it's intended uses, I see no problem with this unit. I use mine for smaller components, stomp boxes, and fine discrete component work. The tip is fine enough for light SMT work, if you are feeling really adventurous. If I have to ground the back of pots, work in old tube/valve amps, that is where the 40w Weller gets used. The right tool for the job.

So no, it is not an industrial Weller. If you need that, get one. Although the industrial wellers aren't the same as the one I used for 30 years as a railroad electronic tech. They've gotten cheaper...

Quote from: Enzo on March 16, 2013, 02:02:18 AM
Ahem, Gorilla here...

When we were playing the clubs back about 1970-1973, we carried a full B3 and Leslie.  We had an 18 foot truck.  I could get the Leslie out of it by myself.  No ramp or lift gate, just technique.  The organ itself, yeah, it needed a guy on the other end.   Leslies are not near as heavy as they look, and I am not especially strong.


Then our keyboardist decided he wanted a piano.  He wanted a REAL one, so we started hauling this full size upright to gigs.  900 pounds if I recall.  That took the entire band to move.   I have always hated the sound of a Fender Rhodes, that distorted "bonk" sound does nothing for me, but I sure would have loved to see one back then.


Here in town, we have a local guitar hero named Frog, and he has been known to put an amp out in the van, and run a mic out to pick up the sound, so he can get the sound of a screaming loud overdriven amp without blowing the whole bar away.  So there is a precedent for the story Roly just posted.

Back in the 70's, my keyboard player had the obligatory B3 + Leslie and an upright piano. I would volunteer to help him carry in his Mini-Moog. Of course, this was after I had to move my full stack Marshall Superlead, and help with the PA (4 Peavey CSP's at 100+ lbs each.) We had a soundman, but no roadies. It was either borrow an 18' truck, or move several loads in my VW bus.

Having etched quite a few boards in my time, I have never delaminated the copper from the board, and like Phil, I use a lot of pressure for a couple of minutes. The heat from the iron has a lot to do with how easily the image transfers. When I used photo paper, I cranked the iron to the max. With PNP blue, a lower temperature makes excellent transfers. Too high a temp with the PNP will make it smear. Then after transferring the artwork, I compare every track to a copy of the drawing I print out on transparency so it can be overlaid with the board and any necessary corrections made. And like Roly, those corrections are made with a permanent marker, in my case a Sharpie very fine point industrial waterproof marker.

Of course, after etching comes the inspection with magnifying glass, and meter check for shorts between traces. Then drilling with bench top drill press, compare to the transparency for missed holes, go drill that last one I missed, populate and solder away.

The only thing I can see from scaling up from pedals to amps is to have a very good idea of your current flow through the different circuit building blocks. Power and ground traces need to handle everything you throw at them, so size them accordingly for the main power busses. Pre amp components draw in the mv range (and micro amps of current) so those traces can be smaller. Power amps deliver a lot of voltage and current, and in a lot of SS amps I have seen, the traces will be accordingly larger.

Have fun, just don't get so lost in the project you forget why you are doing it.

Yup, another spammer snuck in. :trouble

Sometimes you just gotta know where to hit them.

One of the better SS Fender amps I have found is the Deluxe 90 with 90 watts into a single Celestron 12". The clean tone is classic Fender, It does not gripe about pedals, spring reverb, pre out and PA in. The only thing I did to it was to replace the clean channel volume pot that is a 50k linear taper with an audio taper pot. I can't tell you anything about the "drive" channel, because I don't use it (see above about pedals  .) Most of the weight of the amp comes from the massive magnet of the Celestion GT12-100 speaker. Mine has a '99 date on it and I found it for $125 used, so they are quite in your budget with a lot of room for extras. Fairly small and weighs in at 33 lbs (15kg) so easily portable even for us older guys.

Possibly because of the myth that tube watts are more powerful than SS watts that I've seen on too many other forums. They seem to think that driving a tube into it's non-linear region of operation somehow can violate the laws of physics. Too dim to realize they know that non-linear region by another name. Clipping.