westhemann Posted June 7, 2003 Report Posted June 7, 2003 i have a question specifically for the amp guys here.i don't know jack about how amps work or anything about tubes.here's my question,i have an old fender twin reverb and the tubes are old(they are the original tubes and the amp is a 60's model i believe.)and need to be replaced.it has 4 6l6 tubes in the power amp section and 4 7025 tubes in the preamp.what tubes do you reccomend as replacements?i want a singing lead tone and a clear and articulate bottom end.i will not be using the in amp gain as i have a zoom pedal which i prefer.also the reverb is not working on it but the pan seems fine.any hints on what i should look for wrong.also when i replace the tubes should i have the amp biased? Quote
tsl602000 Posted June 7, 2003 Report Posted June 7, 2003 Wes, You're talking about in amp gain, so you have a seventies Silverface amp, not a sixties Twin. I'd recommend either Svetlana or JJ tubes and YES... have your amp re-biased. Reverb could be anything, a missing or broken tube or a broken cable. However, I suspect it to be a missing tube. You mention only four pre-amp tubes. A Twin Reverb has six....... Quote
westhemann Posted June 7, 2003 Author Report Posted June 7, 2003 yeah tsl you are right.there are 7 preamp tubes but all of them are not the same.some are 7025 some 12at7.as far as the type i was told it was a twin reverb but all the face has been torn off,the speakers removed,and a few knobs are missing.the in amp gain is a push pull knob,plus it has another push pull knob that i don't know what is.does that tell you anything? i wish to renovate this amp and anything you could tell me would help. Quote
tsl602000 Posted June 7, 2003 Report Posted June 7, 2003 7 pre-amp tubes???? hmmmm the two 12AT7's are the reverb driver and the phase inverter. Any chance you could post a pic? Quote
westhemann Posted June 7, 2003 Author Report Posted June 7, 2003 give me a little time to get it posted. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 thanks again alex.tsl i cannot find any mention anywhere of a fender with 7 preamp tubes.hope you know more about it than me.i want to put the amp itself in a new box(head form).i've had it for a few years and used to play through it through a 4 by 12 cab.has an awesome bottom end but i need to get new tubes in it and get the reverb working.i bought the marshall when the reverb went out but it doesn't have the sheer presence that the fender does. Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 Wes, I think it's NOT a Fender... Without a schematic and the amp right here at my work bench I couldn't possibly tell you why the reverb isn't working.... Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 it's definately a fender.says fender u.s.a on the back panel.and most of the tubes are fender.i think it probably is a faulty tube like you said on the reverb.i just need to find out what it is so i can get the right tubes in the right spot.maybe it's not as old as i think it is.could it be some kind of obscure 80s model?i got it in about 1993 and before that it belonged to a friend of mine since about 89.it has looked just like that since i first saw it.i bought it for about $100 if i remember right and just considered it a p.o.s. even though it had a pretty good sound.it always had those old tubes though so i think it would probably sound pretty nice with new ones. the in amp gain is very harsh and it has lots of it but the clean tone is nice and is a good base for my gain pedal. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 fender musical instruments,a division of cbs inc. fullerton california thats what it says on the back. Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 hmmm..... there might be a 7th tube added later... some kinda mod. For me it's impossible to tell you what it is. Is there a tube chart inside te cab? Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 no i looked for it.it was stripped down as if someone wanted to renovate it and never did. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 i think i will take it apart today and see what i find out. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 took it apart.everything says either u.s.a. or sprague Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 i found it!83 - 86 twin reverb 2 .look here on the index to the left.under twin reverb 2.it doesn't have a tube layout unfortunately but at least i know what it is.i did find one other with 7 preamp tubes it had the extra one for vibrato. Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 hehe... that's about the only Twin I didn't look up in the Fender amp field guide. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 so tell me,what should i do to restore the sound to this amp besides tubes?the controls are sticky and scratch when you turn them and they don't have a smooth transition in sound when you turn them(for example when you turn the treble nothing happens until you reach about 4 and then it all happens at once)will pot cleaner fix this?any tips are appreciated Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 Wes, First, I'd put some speakers in..:-p Seriously, if you've never worked with tube amps before: The innards of a tube amp contain parts that can kill you. I'm not kidding. If you don't know how to drain the caps in a tube amp, go to an amp repair guy or learn to do that yourself. Check out RG Keen's www.geofex.com and search for the tube amp debuging page. I suggest you clean your pots first. It's alot of work, but fairly easy to be done. Try to find/borrow some other tubes and replace the ones in your amp. That's the only way to find out if you have any bad tubes. You know that you should NEVER run a tube amp without speakers, right? Coen Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 i would have it hooked up to my 4 by 12 cab.why does it matter?something to do with the ground?i want to turn it into a head.i don't like combo amps.i do know that the board can store power after it's unplugged.i don't actually want to change anything i just want to get everything working properly. 1.replace tubes 2.get the pots working properly 3.turn it into head form to make it smaller and to look better that's all i really want to do. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 i just found out why they need to be hooked to a speaker. Quote
westhemann Posted June 8, 2003 Author Report Posted June 8, 2003 hey tsl if i order a matched quartet of power tubes does my amp still need to be biased? Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 Wes, You should order matched tubes anyway, but your amp still needs a re-bias... Coen Quote
tsl602000 Posted June 8, 2003 Report Posted June 8, 2003 you're welcome... you know how to clean pots? Coen Quote
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