Finished my HiFi Amp Project

[bluesbubba]

A while back i purchased a Teeco HiFi tube amp at the swapmeet for five bucks. It has two EL84s, two 12AX7s and a 5Y3 rectifier tube . I decided to get inspired and create a guitar amp from scratch for the most part.

I rerouted the mic jack to the front of the amp and combined the selector switch as well. I wanted it to make it look like a real guitar amp so I added a toggle switch and a radio shack pilot light.

I made the faceplate with a piece of anodized aluminum I got at the hardware store. I built the speaker and amp cabinet from plywood and tolexed them.
Every step of the way I was fabricating something. I found a 1950s Bolex 12" ceramic speaker for the speaker cab.

Well here it is:

[tubeswell]

Wow that's cool - is it cathode- or fixed- biased?

You say its a ceramic speaker but it looks like alot of old alnico magnets used to look (I bet it sounds cool whatever)

[bluesbubba]

Thought it was a ceramic...

It's definitely fixed; no biasing. I thought it was a ceramic speaker by the big "bell" type cap. It came out of a Bolex external speaker cabinet made for projectors back in the 50s, 60s.

[bluesbubba]

This is what I started with...

A Teeco HiFi Tube Amplifier. Not bad fr 5 Bucks!

[tubeswell]

It's definitely fixed; no biasing. I thought it was a ceramic speaker by the big "bell" type cap. It came out of a Bolex external speaker cabinet made for projectors back in the 50s, 60s.

I think it looks like an old Goodmans speaker - could be a Goodmans in a Bolex cabinet.

[bluesbubba]

I think it looks like an old Goodmans speaker - could be a Goodmans in a Bolex cabinet.

Is Goodmans considered a good speaker

[CitizenCain]

I don't know haw that speaker ranks, but it does look like an alnico mag to me. If it has a big bell cap on it, it's an alnico. Ceramics tend to be in the form of a big ring.

That's a sweet little project you go t there! That Teesco looks a lot like the Heathkit I'm perfomring a similar conversion on.

[tubeswell]

Yeah the Goodmans sure are good, they were originally installed in Vox's I believe, but Vox later changed to celestion blues (which were 'smaller' or lighter? for some reason). I put an old Goodmans in a 5F2A I built - it really sings.

[bluesbubba]

I found two speakers at the swapmeet; one was the Bolex with the cabinet and the other was a Bell & Howell with the cabinets; both are for projectors. I think they were both made in the late 50's by their style of the cabs. Got them for $10 each.

That B&H speaker is a Heppner which I found is suppose to be good for DIY cabs, However I like the sound of this Goodman.

I'm off to the swap meet this morning for more finds. Wish me luck The bug has bit me big time when it comes to building guitar amps and collecting amps.

[beedoola]

I just picked up one of these amps. Did you do any modifications to the circuit itself?

[guitician]

I would connect a guitar 1/4" jack and give it a try as is. You may be surprised. The tone control may not work well for bass, but I usually bypass them anyway.

[beedoola]

I would connect a guitar 1/4" jack and give it a try as is. You may be surprised. The tone control may not work well for bass, but I usually bypass them anyway.

you mean the tone control might not work well for bass guitar? or that the bass control might not work well in general?

And you're saying you usually bypassing the tone stack all together?

[guitician]

Yeah, the frequency response of an audio amp is around 20-20000 hertz and playing six string guitar through it can have too much bass. But, that is why I said play it first, because the old amps really lack bass to begin with. And the frequencies that the tone controls are designed for are not the same as they use for guitar. Bypassing gives the amp more room to breathe and lets you tweak it from there.

[beedoola]

Yeah, the frequency response of an audio amp is around 20-20000 hertz and playing six string guitar through it can have too much bass. But, that is why I said play it first, because the old amps really lack bass to begin with. And the frequencies that the tone controls are designed for are not the same as they use for guitar. Bypassing gives the amp more room to breathe and lets you tweak it from there.

Cool. I have one of those 1/4" to MIC adapters. Amp sounds good.

What are some input resistor values to try? I'll also try bypassing the tone stack.

Yes, the bass is too intense. I usually keep the control off.

[guitician]

What are some input resistor values to try?

I'm not sure what you mean here. The input resistor that is there should be fine. Bypassing the TC circuit will give it more gain and distortion, if that's what you like.