Pilot AA-903B Tube Amp

[Kofi Annan]

Well, I had a pretty successful scavenging day down at the local TV repair shop. The haul includes:

* 2 Lindal 12AU7s (never heard of these, but what the heck)
* 2 GE 12AT7s
* 2 Westinghouse 12AU7As
* 1 Pilot AA-903B tube amp w/ matching FM tuner

OK, so probably none of this is going to light the world on fire, but I got it all for a song.

I'd like to know if the Pilot amp is worth keeping and restoring or if its junk and should be disassembled for parts. Also, I didn't realize it until I got it home, but its a mono amp, so that means I need two of them for stereo, right (see how smart I am)?

Mrs. Annan saw me come home with these and exhaled conspicuously. I'll need to act fast so they don't wind up in an impromptu garage sale.

Kofi

 

[planet10]

I understand that Pilots are underappreciated -- meaning they are pretty good (for their day)... whether it is worth more restored or as a ginea (sp) pig i know not...

dave

 

[zobsky]

i own two pilot 903 amps (6v6 push pull integrated)

IIRC, the 903B is a EL84 push pull , .. not sure whether the circuits are similar (although the concievably could be), .. but don't junk that one. get it working and it should make you happy.

if it needs restoring, it will provide a good introduction to tube amp repair etc . since it is a mono amp and therefore, basically easier to understand. .. your public library may have a sam's schematics of this amp which you can photocopy.

later on, you can try tinkering aruond with triode mode, tweakign the bias etc ..


for the record, i like my 903 as much as the much revered pilot 232 el84 power amp i heard at a friends place (although the sound is a bit more coloured)

 

[Kofi Annan]

OK-- here's some photos. Everyone likes photos, right?

 

[Kofi Annan]

And the back...

 

[Kofi Annan]

Now closer...

 

[Kofi Annan]

I know that the EL84 Amperex Bugle Boys are somewhat sought after and may be resonably rare (I think this is right). If that's the case, would it be worth having the tubes tested and trying to sell them on Ebay?

I'm only asking because I intend to restore this amp and buy another matching amplifier, but the chances of me finding the same tubes in another amp are kinda low, I'm guessing, and to buy these EL84s for the second amp could run into some big bucks.

Your thoughts?

Kofi

 

[planet10]

I know that the EL84 Amperex Bugle Boys are somewhat sought after and may be resonably rare (I think this is right). If that's the case, would it be worth having the tubes tested and trying to sell them on Ebay?

Exactly what i thot when i 1st saw the pic... given my guess of how little you paid, they could well cover the entire cost of your purchase (and new SV83s (run within their limits) are probably better sounding.

I'm only asking because I intend to restore this amp and buy another matching amplifier

Restore to original, or tweak a bit for best sonic enjoyment? If the latter i'd use SV83 or the Sovtel EL84M (actually a Russian designation). In the Zen Select the SV83 sound a bit better, but the EL84M are a very good EL84.

If you need some cheap EL84s, i have a box of used tubes -- we could come to some arrangement.

dave

 

[Kofi Annan]

given my guess of how little you paid, they could well cover the entire cost of your purchase (and new SV83s (run within their limits) are probably better sounding.

Well, I paid $20 total for the amp and the matching tuner, so I don't think I could have done much better.

Since you put me in touch with Woody, I'm trying to weasel my way into having him test the EL84s on his tube tester. Also, there are three Telefunken 12AX7s, which could also be quite interesting.

I think I will restore this initially-- try to replace all components and give it a good cleaning. Of course, I'll want to tweak it eventually...

I've looked in vain for a schematic for this amp. I googled quite a bit and come up empty.

Anyone got the schematic for it?

P10-- I'll certainly be in touch soon conerning the box o' used tubes.

Kofi

 

[planet10]

Well, I paid $20 total for the amp and the matching tuner, so I don't think I could have done much better.

Since you put me in touch with Woody, I'm trying to weasel my way into having him test the EL84s on his tube tester. Also, there are three Telefunken 12AX7s, which could also be quite interesting.

In good condition the Bugle Boys should fetch at least $40 and the TFKs $30 (sometimes you get surprised and they can go for much more)

I have a package already scheduled to go to Brian GT so i could tuck some EL84s in there -- would give you an excuse to go meet up with him too.

dave

 

[Kofi Annan]

Hey-- sorry for the delayed response.

Thanks for the offer, but I think I'll hang on for right now. I'm in enough trouble as it is.

If the "box" is still around in a week or two, I'll probably give it another shot then. Mrs. A. is starting to mentally inventory all of the audio equipment and parts and I'm seeing "Ebay Auction # 942753191981L: Big Box of Audio Stuff -- CHEAP!" in my future if I don't become less conspicuous.

I'll ontactcay ouyay in a eekway or so (inkway, inkway).

ofiKay

 

[allnighter69]

Kofi annan i have that amp too, do you have the diagram because i want to restore it these days, please.

 

[Tom Bavis]

Find it here: Pacific T.V. - Online Schematics

 

[allnighter69]

I found it thanks a lot for your help

 

[GeoReed]

Pilot AA-903B

I have a couple of these amps also. I repaired mine by replacing the selenium rectifier, main rectifier tube, with good diodes, and also replaced filter caps. It is an amazingly clean amp and one of my favorites, with a very nice phono section and beautiful sounding output transformer. I'm also looking for a schematic of a Pilot 654 FMA (stereo FM receiver). I've restored it and wish to verify some values on the tuner section. This amp seems to have had a built in problem with hum in one channel,... which I came up with a solution for.
GeoReed