Hifi Tube amps

guitarboy2828

So, my dad is a technician, and he has been for many many years, so he has lots of weird things in his garages.. Something he has a few of is old valve hifi amps. What would these sounds like if i chopped off the RCA inputs and converted them into jacks and plugged my guitar in?

I guess the next question would then be, what would it take to convert a hifi amp into a decent sounding guitar amp?

matta

guitarboy2828 wrote I guess the next question would then be, what would it take to convert a hifi amp into a decent sounding guitar amp?

Alot or a little, depends on the amp. Many old amps have a pair of 6L6's, or 6V6's, a 12AX7 preamp etc, so these are great donor amps, you just have to look and see what you got and then work it back from there.

Cheers

Matt

AlanRatcliffe

Otherwise sell off the Hi-Fi amps and buy another guitar amp ?

guitarboy2828

Haha, Alan, stop giving me GAS.. I blame you for my current bank balance! ?

I will take some pics later and upload them and see what you think. ?

guitarboy2828

Well, here are some pics.. I actually modified this amp awhile ago, before I owned an amp. However, soon after that a valve went poof.. I think it was one of the small ones "ecc 81". The big ones are "EL 81's".

Is there somewhere I can get an ecc 81? is it worth changing the valves?

matta

I have a few ECC81's in stock, otherwise known as 12AT7's.

Cheers

Matt

guitarboy2828

PM sent! ?

nick

Lucky! Im looking around hoping to run into some elderly person who has one of these just lying around, want to use it with a vintage turn table for some old school sound ?

guitarboy2828

Haha, yeah, they pretty cool.. My dad has a few lying around, but I don't know what works and what doesn't.

Karel-Mars

Hey Guitarboy

Those are nice amps! I'm talking about the Philips.

I have hacked around a few amps like these. They have no money value though. If you strip them, only the transformers are usuable. Most of the other parts are so oxidised, you'll get further using new sockets/caps/resistors.

The best thing to do, are to get them working as is, and listen to their sound. I use them to play music, typically outside. Fling together an open back speaker cabinet, and use the amp for vibes while you braai. You can turn the amp up and hear the pentode push pull sound. The uneven order harmonics (distortion of push-pull amps) can be harsh in the house.

The philips output transformers are very high spec. They would probably sound great in a custom amp. If the console amp have pcb's inside, you are limited in modding options though.

The best value these boxes have, are as educational projects. See if you can find the schematic. Or trace the schematic yourself, and you'll learn a lot. These amps were built at the end of an era, and were well thought through designs.

BTW the box looks very retro ? Clean it carefully; it maybe the most valuable part of the amp. The gut all the insides (give us a photo of the inside of the PA console if you can) and rebuild it as a AC15 style amp. Just an idea.

BTW the amps with the octal pre-amp sockets are the ones that you should look out for. They have great mojo!

guitarboy2828

Thanks for the input Karel, I will get this one working again, i remember playing on it awhile ago and it was a decent sounding amp. Nothing studio worthy, but fun for home jamming.

Will post clips when I get a chance. I find the same problem with this amp as the royal, don't really have much time and facilities to use this as a project. ☹ Would be great fun if i could though.. Maybe in the future! ?

guitarboy2828

Karel Mars wrote
BTW the amps with the octal pre-amp sockets are the ones that you should look out for. They have great mojo!

What do these looks like?

FenderBender

@guitarboy: Wow that is one funky little amp. Is that pilot lamp in front molded in the shape of the Philips logo?

To answer your previous q an octal valve has 8 pins, so pull a preamp valve and count the pins or count the solder tags on the back of the sockets.

Regarding the faultfinding/rebuild, I agree with Karel. If you want to get it up and running again, get the schematic and work through the amp carefully, making sure that everything is ok on the amp before replacing valves. A simple blown resistor, faulty cap or dry joint could cost you more valves and waste your time.

guitarboy2828

Graeme Parfett wrote @guitarboy: Wow that is one funky little amp. Is that pilot lamp in front molded in the shape of the Philips logo?

To answer your previous q an octal valve has 8 pins, so pull a preamp valve and count the pins or count the solder tags on the back of the sockets.

Regarding the faultfinding/rebuild, I agree with Karel. If you want to get it up and running again, get the schematic and work through the amp carefully, making sure that everything is ok on the amp before replacing valves. A simple blown resistor, faulty cap or dry joint could cost you more valves and waste your time.

Thanks for the advice Graeme, am keen to get it working, so will spend some time on this amp when I am home and work through the diagram. My dad has checked it before and said it was the EL 81 that was faulty, but I'm not sure if anything else is faulty. Will have to check that out. ?

As to the pilot lamp, I'm not sure what that is. :/