How to? Fender silver to black face

Chris Erbacher · Post by **Chris Erbacher** » 31 Mar 2003 2:59 pm

hey out there, let me say that i hope i put this in the right forum. my buddy just got a really good deal on a silver faced twin reverb (i think it is a '72) and wants to know how to change it to the black faced specs (circuitry....). if anyone out ther knows how to do this and can explain how to do it, that would be great. this may have been talked about many times before, but i told him i would post and see what happens. thanks a bunch

Post by **b0b** » 31 Mar 2003 5:08 pm

Nope, wrong forum, Chris. I'm moving it to Electronics.

Mike Marchelya · Post by **Mike Marchelya** » 31 Mar 2003 5:20 pm

http://www.unclespot.com/FenderBF.html

ajm · Post by **ajm** » 31 Mar 2003 6:45 pm

Get Gerald Weber's first book. It's in there. Call Kendrick amplifiers in Texas to get a copy. A search on the internet should get you to them.

Also, does it have a master volume control? If it were mine I'd consider moving it to where it's after the phase inverter. This is also in the book.

Good luck, and let us know how it turns out.

------------------
Artie McEwan

Gino Iorfida · Post by **Gino Iorfida** » 31 Mar 2003 10:18 pm

First off, it's not that hard to do, however, there are sometimes lead dress issues that cause the amp to oscillate if not addressed when doing the blackface mod. SO in otherwords, not alwas recommended for a first timer mod.

Secondly, tube amps produce LETHAL voltages, that are still rpesent when the amp is shut off even for a period of time. Lethal meaning, yes, they CAN kill you!! Once again, the information is out there on the web etc how to do it (not to mention, if you can read schematics, you can compare the blackface to the silverface and deduce yourself what to do-- if you can't read schematics, you probably shouldn't be poking around inside a tube amp anyways--- in that case, learn how to read schematics, and build yourself a 'matchbox' or a 'fuzztone' etc FIRST, then read up)... there is also jsut as much info on being safe on the web as well, please look at that, and familiarize yourself with it...

Finally, if you have ANY doubt whatsoever of your capabilities, PLEASE take it to a reliable technician. A good tech can get the amp blackfaced, and do a good tune up (filter caps changed, bias set, any out of spec components replaced etc) for under $100. A cheap insurance policy if you ask me!

Chris Erbacher · Post by **Chris Erbacher** » 1 Apr 2003 2:53 pm

Thanks for all the info guys, i looked at it last night and it needs some tlc, but it sounds good. the bias is off and seems to be not loud enough? but the tone is clear and the vibrato doesn't work, reverb does. i suggested to him that he take it to sal trentino, who lives up the road a bit, and just ot take it to him and spend the money to get it done right. i guess we'll see what happens, great shape though and a really good deal made it hard to pass up. i guess it never even made it out of the back of the guitar store before it was sold. one of the guys working happened to mention it to him during a conversation. does anyone know what speakers were stock on a '72 twin? it says that there is a 4 ohm impedance to this amp, does anyone know if he was to plug the extension speaker into the main jack on a peavey delta blues amp, would it hurt the delta blues? it is rated at 16 ohms. does the extension jack have to be rated at the same impedance as the main jack for them to work right, or is it just a vehicle for the signal? thanks in advance for the advice.

ajm · Post by **ajm** » 1 Apr 2003 5:37 pm

Quote: "does anyone know if he was to plug the extension speaker into the main jack on a peavey delta blues amp, would it hurt the delta blues?"

YES IT WILL HURT IT. DO NOT DO IT. The Twin has an "extension speaker" jack. It is not made to plug into a regular instrument level input.

Someone else with more knowledge want to field this one?

------------------
Artie McEwan

Bruce Derr · Post by **Bruce Derr** » 1 Apr 2003 7:26 pm

Chris, are you asking if you can connect the Twin's extension speaker jack to the "main" speaker output jack on the Peavey Delta Blues? If so, the answer is no; you'll be connecting the two amp outputs together, which is not good.

If, on the other hand, you meant "can I connect the SPEAKER in the Delta Blues, which is 16 ohms, to the extension speaker jack of the Twin," then the answer is Yes, as long as the Delta's SPEAKER is not plugged into the Delta Blues AMP when you do it. Also note that the 16 ohm speaker won't get nearly the same amount of power as the two speakers in the Twin, so it probably won't be as loud.

Gino Iorfida · Post by **Gino Iorfida** » 1 Apr 2003 11:31 pm

All I can say is DO NOT DO IT!!!

If you plug from the extension speaker jack to the input (or line in etc) of the delta blues, what your friend will have on his hands is 2 dead amps. Guaranteed 1 will have a blown output transformer, which will be expensive to replace (Fender), and who knows what else wil fry.

As for plugging from the extension speaker jack to the delta blues speaker only (make sure the speaker is unplugged from the delta blues == going from the extension speaker jack to another will backfeed the delta blues, bad news, I'd also not recommend using a 16 ohm speaker off the twin's 4 ohm tap. This would be a gross impedance mismatch, and could and most likely would cause the twin to behave as if it was running open circuit, which could produce flyback voltages that could damage the output transformer, damage the power tubes (the way a traansformer interacts with the tubes, is that the impedance of the speakers is multiplied/reflected off the speakers impedance, so instead of seeing an impedance load of of 2000 ohms, with the 16 ohm speaker, it would see 8000 ohms, WAY out of spec! -- esp at the voltages a twin runs at, this would be a surefire recipe for disaster!)

Chris Erbacher · Post by **Chris Erbacher** » 2 Apr 2003 12:23 am

Well, here is the latest news.... i left my amp, the delta blues amp at my friends house overnight (the plot thickens), turns out that he went ahead and plugged the extension speaker into the main of the delta blues (bad idea, i told him so last night to wait until i got more info, but he didn't listen), and he said he didn't like how it sounded. the weird thing is that i played thru it today and it didn't seem any different than it did yesterday. i'm wondering if he plugged it in and something happened that he knew right away it was the wrong idea, and quickly unplugged it. i guess i'll have to see tomorrow if something is wrong with the amp, we were playing at really low volumes tonite, so if there was damage, i probably wouldn't have noticed it anyway, so back to the story. i guess he took the amp to sal trentino (neil young's tech, santana's tech, pearl jam's...) really great guy and a great tech. the original fender speaker was blown (i am not sure why he didn't notice this in the store, but he got a great deal anyway, so i guess it doesn't matter). so bottom line is he is getting great service, getting it blackfaced and completely gone thru and i guess sal is going to just go all out to make it sound the very best it can sound, so we'll see when it comes back. i really appreciate this forum and it's collective musical I.Q. what should i look for with my delta blues ? will it be easily noticable if something is wrong? or is it subtle? once again, thanks for all the help, i tried to tell him about the impedance differences....... if anyone out there wants sal trentino's number, let me know by my email and i will get you his number. take 'er easy....