JohnnyG

one of the best places that explains alot about the building blocks of tube circuits is http://www.aikenamps.com/ go to tech info and then have a look around. the stuff in introductory is the basics. theres a list of must have tube books, a list of commonlly used amp terms etc etc. its stuff that you may already know but its worth checking. the advanced stuff is really ace. explains things like designing common-cathode triode amplifiers from the ground up and has a fair bit of info on biasing. unforunatelly there are still a few things i think it misses, like it doesnt have a very good description of the Load Line technique for biasing tubes IMHO. however thats where i really started getting my good tube info. otherwise tbh you just need to make sure you have a really good graso of electronics. tubes in truth are very simple beasts and IMHO people only think its tricky and voodoo because a) its old, it uses high voltages so its scary, c) some amp techs make it seem like you have to know everything to make a good amp like everything else in electronics, get down the basic rules and a good understanding of how it all works and its simple

LK tant caps are generally considered to be serious anti mojo. mainly because they have a much lower life expectency than anything else and so are normally the first thing that needs to be replaced in old pedals. Uncle, if you can get miniature poly film caps then they will be fine for what you want, even electrolytics would do nicelly tho there is the space issue. i would have thought that unless you're trying to make the circuit tiny (im guilty of this, entire fuzz face circuit on a 2pence sized PCB anyone ) then you should have enough space for either of them oh, and like LK said. spend a bit more on the Op-Amp. get a half decent one for maybe a dollar or two. if you really wanna be flash then get a burr brown opamp, they're pricey but good from what ive heard

syxxstring: Tom definatelly has everything running after the distortion in his rig. the Wah pedal sound he gets is definatelly a result of it runing after and the same with the digitech. it sounds completelly different before and after distortion as well. i thought that most FX loops came with a volume control on them? i can see what you mean about the levels tho EDIT. ive just noticed on that rig he has the wah before the amp yet other places ive seen his rig with it in the FX loop. also there isnt a phase 90 or a trem pedal which im positive he's used. i think that rigs a bit out of date but the point about the levels still stands lol

as far as i know the worst you can do is have them biased too hot which could lead to the output tranny and/or the tubes frying. id try to work out what the biasing voltage would be if you had those tubes in and then check to see what the biasing would need to be

i'll second that. is mildlly annoying that they dont do the 7 string version anymore tho

i have no ideahow oldit is. Bigd told me he had hardlly any info on it lol. im fairlly sure that the 6sl7 is a phase splitter but i cant see how. the cathode of one is joined to the B+ supply directly at the rectifier through a 220k resistor. the cathode of the other tube is joined to the plate of the 6v6 its driving via a 560k resistor. the cathodes arent joined together which is how im used to seeing phase splitters. in truth this isnt really a major problem since i can just rewire it to be a "normal" phase splitter when i rejig the tone controls. the only real problem is that im fairlly sure that the power tranny is for 120v usa and im not sure if it has two primary windings so i can turn it to UK voltage. its a really big power tranny but it does have secondaries for B+, Heaters and then the tube rectifier heaters. i may have to take it out the amp and take the cover off the top to have a look there are one or two other little oddities like the spare 6v6 power tube that doesnt seem to do anything but it'll be alot easier to ask questions as soon as ive got the schem up on the computer.

aaahhh ok. i figured the colours were the same as resistor codes i just didnt have a clue how to read them. as for the power amp section its actually fairlly normal....well i say that. its push pull using 2 of the 6v6 tubes. the third tube isnt even connected into the signal chain which has really confused me. it seems to be connected up in some wierd way to a mono type input. its got the heater connections but then everything else is wierd. the cathode is connected straight to ground and then the other pins all seem to be connected to something that im guessing is a large variable inductor i have zero idea what the hell it could be, short of guessing at some sort of tube burn in section to store a spare power tube ready in case one goes??!!?? id really love to know. other than that the tone controls are a little wierd and it seems that if the dual triode is used as phase splitter it isnt a design ive seen. im gonna check it through all again just to make sure i got it all right. so just to make sure with the cap thing. i have a cap here that is White Red red brown silver red so that would be 220 nF ye?

lol. atm im about half way through drawing out a schem of thething. everything is fine so far except for 2 things. one is that while i havnt got there yet i suspect that the power amp topology is gonna confuzzle me. second is that there are these old school capacitors inthere lol. they're plastic. square (some are smaller oblong ones) and they're flat. they have the value codes on them in the form of 6 little coloured dots. but i have no idea how to read them. the middle dot on one side is silver on all of them so i assume thats tolarence. any other help would be welcome lol with regards to the layout this thing has a 6j7 pentode at the input (i was really stumped for awhile untill i realises that the wire off the top of the tube went to the jack lol. couldnt figure out where the signal went) then theres the volume control. then into a 6j5 single triode from there it has some kooky tone controls that really confused me for a bit. the tone pot is some strange blend pot. blends between two simple RC networks at each end and thentheres another RC conected to a 4th lug. i worked out using my DMM that in the middle its a direct connection to that and then as you move towards either end. from there it goes into a 6sl7 dual triode (havnt worked out all the connections yet) and after that there are 3 6v6 pentodes. which is what im not sure about. i know enough about amps to know all about single ended and push pull topologys etc etc but what are 3 tubes for? i dont think the dual triode is being used as a phase splitter (will soon find out) and i didnt think you could use a triode as a phase splitter.

ah ok. i can see what you mean now. many thanks for that, definatelly something to remember. i assumed that even if a power tube went and shorted to ground then the cap would be ok because its not actually in the direct line of the short (if u get what i mean) you learn something new every day

looks likeyou're not the only one having to deal with funkeh caps now. i got the old PA tube amp i bought off BigD today and im currentlly tracing it out. has 2 big metal can caps in it. one is a straight 40uF 450V. the other is a 40uF 450V and a 25uF 25V cap in one can. christ knows where im gonna find any of those if i need to replace it. thedoctor: how can you tell that the cap is bad? not dismissing your opinion, just interested as to what leads you to that conclusion. interesting about reforming capacitors as well. im assuming thats a result of them sitting around unused for so long

woot. someone in the uk selling stuff. ill go have a look now man

like wes said it happens. some people put a small capacitor across the volume pot lugs to counteract this. the other alternative if you really want is to put active circuitry inside which can get around it but thats a whole new kettle of fish

wow a picture lol. i think Paul is right on this one. seems that its gotta be a common ground with the four outer lugs, otherwise they would all have to be connected somewhere. no all you gotta do is check the sucka

from what i know they both have pretty much the same circuit board so if you want to chop and change them then it wont make much difference. id go with the TS-9 but only really because its cheaper in this case. soldering stuff wont be espescially hard

by the sound of it the metal can actually has 3 seperate caps in it of 40uF each. 6 connectors for the caps and the 7th will be a ground for the case. it is still possable to get cans which contain multiple caps but like paul said it would probablly be alot easier to replace it with new caps. this is assuming of course that thats whats blown. personally i think it would be ok since i dont think an excessive current draw through the resistor would have fried the cap since i dont think it would have gone above the rated voltage and i cant think of how else it would have damaged it. id still check it tho lol if you have a good multimeter then that might be ableto measure it tho looking at mine it only goes up to 20uF im sure if i thought about it i could think of a way to do measure it with a pulse generator, a smallish resistor and an oscilloscope. but that would probablly be a bit of adance to sort out and you'd be much better off asking the TV repair guys. in general im still of the reckoning that its power tubes that went first and started everything off but then theres that "opinion backed up by little experience" thing ive got going so dont take my word for it.

id really love to find a tube guru around me but unfortunatelly i doubt id find any without taking the train to london. theres always my uncle who's pretty nifty with electronics but he's definatelly not within walking distance

it should be fairlly easy to do what you want. just open the guitar up. check to see which wire connects from the 5 way switch to the volume pot. chop the volume pot off and then connect the wire straight to the output jack. the buzzing etc could be because the tone controls are chopped off and so there's then no attenuation of stuff picked up by the Pups. you could get around that easilly by just installing a fixed resistor instead of the tone control. just make it the same value as the current potentiometer

i still have a little pea sized lump on the inside of my right arm. reached across a breadboard to turn the power on to a project at school and i sent 25 volts through a little 18 volt electrolytic. the metal case went straight up into my arm and then bounced off and half way acrossthe room. i still got full marks for safety tho

wow. i dontthink ive even hit 100 yet. despite me being alot better at tinkering with electronics than guitars i always seem to have alot more to say here than over there. probablly because here i can talk about electronics and people almost think i know what im doing

having not seen a pic of the pot i dunno if im totally right but is it one of those cermet multi turn pots that looks kinda like this if not i know that aikenamps uses special screw pots for the biasing in his amps so in a pinch you could email him for info Aiken Amps

a stereo amp is something ive thought of a bit tho for me it would be a case og building a beastlly 7 string baritone, then having the signal split to go to a normal amp and then a bass amp. im sure my dad has told me that way back when there was a guitar that had split Pups and two signal outs. so you could have treble strings to the right and low strings to the left. and on another note. how many people are there her who are on the DIYStompbox forum? seems every time i go to either there or here i see someone else i recognise lol

please note that i have no practical experience with building/trouble shooting tube amps (yet ) and the following knowledge is gleaned from what ive read and my own knowledge of electronics. from the way that i see it, if the resistor is hooked up to the smoothing capacitor and the pot that could be responsible for biasing is fried as well then it may have been a power tube go imho tube goes -> short circuit -> draws way too much current through the resistor in the B+ line and also through the pot -> fried resistor and pot this could have damaged the rectifier posablly the power tranny and if you're unlucky the output tranny but im not totally sure. however since you say it turns on and you get sound for a bit i dont think any of these are. id still check tho. if the amp has an output before the power amp section you could always take the power tubes out (to eliminate any posability of damage to output tranny) and then run a signal from the pre-amp to another power amp. that way you can tell whether the rectifier/PT is ok with regard to the resistor, like paul said its notin thesignal chain so it wont matter what type it is. from what it seems its in the B+ supply to hekp with smoothing so just pick a resistor that can handle the power. i hope that at least some of thats helpful. like i said, my practical knowledge doesnt extend to tubes yet. its a case of reading alot of books/websites but not having got my hands dirty lol

i recentlly got some of the hercules guitar hangers and everything seems to befine with mine. i have my kramer, my project strat and my tatra acoustic up there. the project guitar is out of tune when i take it down but it has a tendancy to detune sporadically so im fairllysure its not the hanger. StratDudeDan it sounds like you've got some quite cool stuff going on. im almost tempted to start a thread for people to put up pictures oftheir entire collection hung on thewalls (tho i think it might have already been done). atm mines hanging next to my collection of old skateboards

yeah like it says on the shcem lovekraft posted its supposedlly responsible for the fuzz from satisfaction. only problem is that it looks to be a fair bit of wiring and atm all i can build stuff on is perfaboard which is really not fun. with regards tothe loss of volume i wouldnt have thought that would occour. id check the transistor in there that they're using as a squelch control and maybe play with the biasing voltage on it

IMHO id go with the Boss SD-1. from what ive heard the zakk wylde overdrive is basically the same but without the output buffer and some tone control mods. and the tube screamer is much the same as both of them but has much more of a midrange sound. the OS-2 im afraid i dont know anything about however what the SD-1 has over all of these is a price tag thats considerablly cheaper and what it shares with the TS and probablly the Zakk is that its a very tunable circuit so if you feel like modding it to get better/different sounds then theres a wealth of info on the net. however, if you're planning to use it with your amps overdrive channel then regardless of what pedal you choose you might get a case of too much distortion turning the signal to mush. overdrive pedal into overdriven amp doesnt always work so bear it in mind there are a few pedals which do actually do it very well. if you can track down a DOD juice box then ive heard that while the stand alone distortion is nothing amazing it can do wonders for pushing an already distortied pedal/amp nearer to the sound you want