Victor "Model 60" Projector/Amp - Advice please

[infiniteposse]

Hi all-

Today I scored an old projector with an integrated tube amp and an external speaker. I'm curious if you guys could take a look at it and give me your thoughts re: it becoming a serviceable guitar amp.

I'll layout the basics:

- Victor model 60 projector/tube amp
- Tube compliment: 2 x 6L6, 5U4, 6SJ7, 6SN7
- Controls - Volume (one is located on one side of the chassis), Volume 2 (master vol. perhaps (?) on other side of the chassis), treble, bass
- Basic's I'll need to install: 3-prong power cable and speaker output jack.
- All point to point and pretty dense at the moment on the interior. I'd like to gut the projector parts of the amp and get it down to the essentials of the amp circuit.
- I've gotten the projector physically out of the case and I'll be using the metal housing as the cab for the time being. It'd be way premature to think that this is worthy of it's own new shiny cab at this point.

My skill level:

- I'm currently working at a local shop doing recaps, so I'm solid with a soldering iron and my work is clean. I've done a few jobs inside point to point amps and I actually really enjoy the aesthetic aspects of careful layout.
- I'll be able to ask some questions of my boss re: how to do some things, but he's a busy guy, so it's best I do as much of my own footwork as possible before bothering him with every little detail.

Basically I'm curious about what you guys think of the amp as it is now:

- Is this "circuit" usable for guitar?
- If not, what would you suggest I move it towards design-wise?
- How would you approach this project?

I've got a 53 Deluxe (5B3) and I really like the sound of octals, so I'm excited about having more of that sound, but I'd also be open to putting in octals if the best fit for the amp dictated it. I'm guessing the major limiting factor is going to be having just 2 preamp tubes to work with, yes? Could I do something like a Tweed Champ circuit with more juice?

All photo's: http://s18.photobucket.com/albums/b149 ... 60%20Amp/

Here's a schematic and some shots of the amp:

[IMG:990:638]http://i18.photobucket.com/albums/b149/ ... ematic.jpg[/img]

[IMG:917:618]http://i18.photobucket.com/albums/b149/ ... detail.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... b82089.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... a49548.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... 1ab011.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... 0ea757.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... 22c70e.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... 14b070.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... 6c9d49.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... e7d7c6.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... 39f555.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... c83a3f.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... 64f8a5.jpg[/img]

[IMG:764:1023]http://i18.photobucket.com/albums/b149/ ... fa4519.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... 9a657b.jpg[/img]

[IMG764]http://i18.photobucket.com/albums/b149/ ... e6e54d.jpg[/img]

[Cliff Schecht]

I wouldn't even bother with a recap. Heck, I would probably never actually turn that on. Those old Tiger and CD wax/paper caps are known to drip wax and either open or short depending on how lucky you are. When they short, the results can take out an entire amplifier (output tubes, iron, etc..). I'm sure you know the electros need replacing and a lot of the carbon comp resistors could be bad as well (depending on how well this was stored). The amp is in great shape internally though, no rust on the iron or any major issues.

Two octal triodes will be enough to get some real balls out of a pair of 6L6's. You can bias the power stage so that it saturates a bit sooner and gives a great full-on distortion sound. I built a 5B3/5C3 style clone using 6L6's and I absolutely loved it, a lot of power for such a small amp and fun to play lead on. I still use this amp at practice sometimes. The only big issue is that with the octal preamp tubes you get a bit less headroom and so the clean is never very loud. With the 6L6's this isn't much of an issue though, this is more of a quip associated with 6V6 all-octal Deluxes.

[infiniteposse]

Thanks for the feedback.

Question - How would you proceed with this process if it were you? Would you gut the chassis and build in a new circuit from scratch? Remove individual components and reinstall them as you go? Draw some sort of layout, gut and rebuild things as they are now?

I've never undertaken something this complex, so process is what I'm trying to get my head around.

Lastly, based on the schematic, any idea if this is a usable circuit for guitar as-is, or is this going to be a poor fit? Is there any clear way to suss out what's projector/mechanical power and what's the amp's audio circuit? I was thinking I could just trace the wires at the 3 points that junction with the projector and just remove them and any accompanying circuitry, but that feels sort of "best guess" which might not be prudent.

Sorry for all of the newb questions and thanks for the help.

[Alexo]

Whew, there is all kinds of kooky stuff going on in there! I would really just gut 'er and and reuse the chassis, transformers and sockets for a fresh build. You'll still have to figure out what';s going on with that extra transformer on the speaker assembly (which does not appear to be an inductor, as one might expect).

You could build an octal AC15 with the pentode preamp into a long tailed pi and 6L6's, could be very cool... or you could replace the preamp pentode with a dual triode for a more traditional preamp - tone control - tone recovery/driver - pi - output tweedy configuration.

[Structo]

Looks to be untouched!

Pretty cool looking amp really.

Have you powered it on yet?

If it doesn't hum too bad you can probably use it but I'm sure it is at least 50 years old or older.

Please don't gut it and build a new amp in it.
It is worth too much as is to do that.

I has a microphone input and phono input.
Unfortunately neither of those match up to a guitars impedance very well.

The problem I see with this amp is it is really crammed together into a small chassis making it hard to work on.
Replacing all the E caps would be quite a challenge looking at the photos.

What I would do to make it guitar friendly is to add a 1/4" jack but I don't think I would drill a hole, maybe make a bracket out of sheet metal that can be attached with an existing screw.

Buy a 1/4" shorting jack, it will have three lugs.

This way when nothing is plugged in it shorts out the input killing any hum.

Put a 1 Meg ohm resistor across the two lugs on the jack and then a 33K grid stopper resistor in series with the tip of the jack lug to the grid of the first preamp tube. I would solder this resistor right to the tube pin that is the grid.
Solder the braided shield to the sleeve lug of the jack.
On a 6SJ7 that appears to be pin 4. Having the grid stopper directly on the pin will make it less likely for noise to enter.
On the grid end of the shielded cable trim back the shield about 1/2".
Then put some heat shrink tubing around that to prevent the shield from touching anything.
Then solder the center conductor to the 33K resistor that is soldered to pin 4 of the tube.

When you screw the bracket holding the jack to the chassis, that will ground the jack.

Not sure if you will have to disable any of that other stuff that is there for it to work right.

Here is a picture of how the jack will look.

[billyz]

That is a real odd one. Probably high end for it's day though. Look at all those chokes.

Turn it on, does it hum? Real loud hum, if so replace the three power supply caps.And the Bias cap. Probably want to replace them anyway. if no or very low hum, plug in to the microphone jack, any sound? If not check the speaker. I would not be surprised if the speaker is some high impedance type, like 30 ohms, 24 ohms, etc. Might be 4 or 8 though. The weird secondary speaker matching transformer is probably to run a bunch of extension speakers , maybe with matching transformers.

anyway, I think it's is going to be a bear to turn it into a fender tweed etc. You might like it as is if it works. If not the tubes are nice if good. might be able to salvage the PT , pots, sockets, cool speaker cab, who knows what else. If the speaker is 4,8,16 ohms and works great. The OT situation will need to be figured out.

Cathode biased looks like a split load PI with a pentode pre. Might be pretty bitchin.