Heathkit TA-16 Guitar Amp

build it and jam, that's what the instructions say,

transistor job, single pwr supply with output cap,

pair of sq mag 12's,  Chicago Telephone Supply, (CTS  EIA code 137)

dried up lytic killed the vibrato, replaced it but now the NSL cell does not work, (black box)

if anybody knows where to get one....  same company that makes some of the LDR's for the LA2a

pretty good solder job, probably a Hammie who built it for his son to make money of him when he gets Beatle rich, if he is under 18, the folks get the $$.    or maybe it was a factory job,

output cap and inside p/n on motorola,

edit; that's the pwr sup cap, doh

schematic online, whopeee!

how does this thing sound? loud, with the transistor mid-range sound,

i'm out.

Hey CJ!

  I have one of these in storage.  I got it cheap like 30 years ago and even used once on a gig when my amp was being repaired, it got me through.  I soon gave it away and the guy gave it back to me 10 years later. I recapped it just to see how it would change. No change really. The signal to noise is poor so my guess the transistors are off or it was always bad. The  vibrato works though and is my fave sound from it. I like the speakers too for some reason?  These days it's not worth shipping the whole amp.

Cheers!
Lance

cool beans! now i got to get that vibrato going, the lamp in the black box is good as i see the voltage move from 1 to 10 volts, so now to splice in a new LDR, yes those speakers seem to have a rep,

> The signal to noise is poor

Mark Hammer said the same, and said that replacing the input transistors helped. Generally <1V guitar signals won't damage transistors, but bad things happen on stage, and these are very very old transistors.

Is that "2N3391"? This is a selected PN100, which is the Adam of many thousand small Si NPNs. We could throw in many high-hFE NPNs, but the 2N3391 is apparently readily available at Mouser.

hitchhiker said:

The signal to noise is poor so my guess the transistors are off or it was always bad.

Click to expand...

I would think it's poor from the first moment. The input impedance of the first stage is 10k, so, with the 22k resistors, you start with 10dB signal loss. In fact considering the source impedance of an electric guitar, the attenuation may be more like 20dB. The rather high collector current (about 1mA) suggests a rather high NF (about 12-15dB).
I guess Heath considered guitar amplification not worth much attention, as witnesses the class-C output stage.

much better schemo,  with DIY LDR box:
http://ctgelectronics.weebly.com/uploads/3/1/6/6/3166248/ta-16_schematic.pdf

did you notice the dual circuit breakers?

2N5088 for input amp mentioned over at Enzo's place

Heathkit manuals>
http://www.vintage-radio.info/heathkit

anybody have the schemo for the Heathkit bug zapper? thinking it could be converted into a road rage tazer? 

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CJ said:

2N5088 for input amp mentioned over at Enzo's place

Click to expand...

2N5088 a tad better than 2N3391, but still 10+dB noise factor with 1mA collector current and Rs=100k. Shorted input noise may be better than with 100uA. Anyway, 1mA needed to allow driving 10k pot and Baxendall.

> high NF....not worth much attention, .... class-C output stage.

Heath didn't make much junk. I suspect it was about transistor cost. This is nearly the LEAST number of transistors possible to bring two geetars to high power with tone, reverb, and trem.

The final stage bias seems to be a Si diode against a Si and a Ge pair. It's perhaps shy of what we'd do today. OTOH, CJ's #10 PDF shows 18.3V-18.2V or 0.1V across two 1.0 Ohm resistors. 50mA ain't too shy, and 50mV is remarkably close to an "ideal solution" (28mV). Plus or minus tenth-volt rounding on the notes, of course.

I have a TA-27, essentially the same but single speaker and single channel, so not as wide. It was original to me and my older brother when I was about 10 years old. I did most of the building and playing. I blew out the speaker a couple of times, so the second time I got a higher power 12" from (of all places) Radio Shack. It sits upstairs, I haven't plugged it in in many years.

Looking online, some have sold for $200 and up (!!!). I should fix it up and get rid of it!