Want to Identify "tube amps" made by General Radio Co. Mass.
Jeff
Gain, and Output. Here's some pictures, just paste the url into your
browser.
http://members.bellatlantic.net/~statik24/Top.jpg
http://members.bellatlantic.net/~statik24/Angle.jpg
http://members.bellatlantic.net/~statik24/Side.jpg
There are 6 tube sockets that are labeled with the tube numbers:
V-1 5751
V-2 5751
V-3 5651-WA
V-4 5727/2D21W
v-5 5727/2D21W
v-6 6626 OR OA2WA
One Power transformer, General Radio Co. Cambridge Mass. USA.
Type No. 485-490
Two Transformers NO. 345-468
At one end there are 4 wires, two white wires with grey & black
stripes, and two white wires with grey & brown stripes.
At the other end there is some kind of 7 pin connector with a threaded
sleeve around the pins.
These were being thrown away, and I thought if they worked I might be
able to use them to amplify my guitar. I have two of these units and
they are very nice physical shape.
If someone could tell me what they were used for, about how old they
are, what the wires and 7 pin connector translate to, is each unit a
stereo amp? Are these tubes hard to find or extremely expensive? Any
information, links, text files or advice would be very appreciated. I
would ideally like to use these to make a stereo guitar amplifier...
Thank you.
Jeff
Shiva
"Jeff" <sta...@gci.net> wrote in message
news:6660372.02070...@posting.google.com...
> I'm pretty sure these are audio tube amplifiers, there is a pot for
> Gain, and Output. Here's some pictures, just paste the url into your
> browser.
Hi Jeff.
Gen Rad was a great local company, making, as far as I know, mainly test
gear, built like tanks... I'd guess that these are amps for some test
gear... They're not power amps. Thou, hey, dont't toss them, anything Gen
Rad is neat...
-dim
Fred Nachbaur
With those tubes, it's certainly not an audio amplifier in the usual sense:
Jeff wrote:
> I'm pretty sure these are audio tube amplifiers, there is a pot for
> Gain, and Output. Here's some pictures, just paste the url into your
> browser.
>
> http://members.bellatlantic.net/~statik24/Top.jpg
> http://members.bellatlantic.net/~statik24/Angle.jpg
> http://members.bellatlantic.net/~statik24/Side.jpg
>
> There are 6 tube sockets that are labeled with the tube numbers:
> V-1 5751
> V-2 5751
These are essentially 12AX7's.
> V-3 5651-WA
This is a gas voltage reference tube.
> V-4 5727/2D21W
> v-5 5727/2D21W
These are thyratrons, gas tubes used as "trigger" devices.
> v-6 6626 OR OA2WA
Another gas regulator tube.
My thought is that it's some kind of precision oscillator, maybe
telephone related (ringback signal or ??)
It most certainly will not make an easy conversion to any kind of useful
audio amplifier, it doesn't even have any power amplifier tubes in it.
The 5751's could form the basis for a preamp, but that's about it.
Sorry to be the bearer of bad news...
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
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+--------------------------------------------+
John Byrns
sta...@gci.net (Jeff) wrote:
I don't think this is an audio amplifer, I think it is either a regulated
DC power supply, or more likely a control unit for an AC Voltage
regulator.
Regards,
John Byrns
Surf my web pages at, http://www.enteract.com/~jbyrns/index.html
Jeff
I'm not going to have a use for these. I want to build a tube
amplifier for my guitar. Im thinking of building either a 4 or 8 watt
amp from Fred Nachbauer's site. I kinda wanted a louder amp, but I
only have minimal electronics knowledge and wouldn't really want to
mess with anything too big. The main thing is not to touch any charged
capacitors. Is there any specific methode that I can discharge them
safely? Like an insulated screwdriver? hah. I'm on a mission to build
my own guitar tube amp, so any help or links for an advanced view of
the basics would be nice. I'm fairly intellegent and I can follow
instructions and schematics as well as use common sense and caution.
Just so you guys know I wount electricute myself without using common
sense and caution. haha. Think those Gen Rad things will sell on Ebay?
Anyone want to trade for help/parts for my guitar amp?
Thanks.
Jeff
jby...@enteract.com (John Byrns) wrote in message news:<jbyrns-0907...@216-80-98-77.d.enteract.com>...
Shiva
Hi Jeff.
The safety stuff first, since you seem to be concerned with it:
To discharge filter caps, use a 'gator clip jumper wire, one end *always*
attached firmly to chassis, while shorting the caps with the other end. If
you don't like the annoying "pop" sound & black burnmarks, use a ~25ohm
resistor at the ehd of the jumper. keep the jumper on the cap for at least
a couple of seconds, 'coz after the initial zap, the caps still come back.
If you're using a resistor, double-check that the caps are discharged with a
plain jumper wire... Thjen, after you're sure that *all* the caps are
discharged 9and I'll get flamed for this), keep one hand behind your back &
quickly brush the cap with a finger. If you *did* somehow screw up, you'll
get a slight shock, but *slight*.
When you're working on the amp, never rest one hand on the chassis - try
to do almost everything with insulated tools, and, just like with driving at
goofy speeds, always keep the worst-case scenario in mind, and plan for it.
On the bright side, I don't know anyone who's been killed or seriously
hurt by working on audio gear...
g' luck,
-dim
Jeff
> The safety stuff first, since you seem to be concerned with it:
> To discharge filter caps, use a 'gator clip jumper wire, one end *always*
> attached firmly to chassis, while shorting the caps with the other end. If
> you don't like the annoying "pop" sound & black burnmarks, use a ~25ohm
> resistor at the ehd of the jumper. keep the jumper on the cap for at least
> a couple of seconds, 'coz after the initial zap, the caps still come back.
> If you're using a resistor, double-check that the caps are discharged with a
> plain jumper wire... Thjen, after you're sure that *all* the caps are
> discharged 9and I'll get flamed for this), keep one hand behind your back &
> quickly brush the cap with a finger. If you *did* somehow screw up, you'll
> get a slight shock, but *slight*.
> When you're working on the amp, never rest one hand on the chassis - try
> to do almost everything with insulated tools, and, just like with driving at
> goofy speeds, always keep the worst-case scenario in mind, and plan for it.
> On the bright side, I don't know anyone who's been killed or seriously
> hurt by working on audio gear...
> g' luck,
> -dim
I see, I think I would get anoyed with the pops. Slight shock eh? I
don't like getting shocked, I might actually just use a meter at that
point. I see, so maybe I should lean back a little so if I get shocked
my body weight will pull me back! :P Well thanks for that piece of
info, that was exactly what I was looking for. I decided not to dive
in head first with the tube amp idea. So I just ordered an 8Watt 8Ohm
Monoblock tube amp kit. I should be able to get my feet wet, and grasp
the idea better. After I build that I want to make a simple one from
scratch. Then eventually make a 75-100 watt amp with distortion and
clean channels and spring reverb. Thanks again.
Jeff
Shiva
Hi again.
You know another fun /cheap way to learn the basics? get some book from the
library on basic electronics, that hopefully has a tube section, and *a junk
tube amp*, like something from a console stereo, that you can always find in
the trash /ask a friend for /find at a yard sale. It would be nice if it
was in somewhat working shape. As you're reading the book, just poke around
inside of that junker, try to figure out what's being done, how, and why -
like a puzzle. I've learned everything from auto stuff to programming to
electronics by ripping stuff apart 9or looking at other people's code &
trying to modify it), and then reading the theory becomes an enjoyable,
rather than "&%$#! I have to learn this" proposition.
You're into guit amps, so you're probably a player, so, if you want a
whole bunch of schematics of tube amps, buy the Groove Tube Amp Book. I
can't stand Groove Tubes & all the marketing hype associated with them, and
the first part of the book is pretty anoying, self-congratulatory, and
dead-wrong in parts. OTOH, it is short, has a bunch of pics of old tube
amps & guits, and, the bulk of the book is a compilation of tube amp
schematics. Look at the Champ schematic - that's probably the simplest amp
you could build., and, they 9or some of them) do sound fun... Very basic,
the book also has wiring /chassis layouts... Worth the 40+ bucks - I use
mine all the time (though I know most of the common amps by heart, i don't
remember my GF's phone #... (i just have it programmed on my phone)). In
short, get your hands dirty - it's the easiest way to learn.
As far as using the meter for the final "discharge" test, there's a
problem 9at least for me) with that: sometimes there's some flux or oxide
on the solder joint, and the meater may flutter 7 read low, and, sometimes,
the foolish thing could be broken /have a bad battery (one time I had to
re-design a power supply, 'coz I got false readings on the AC scale of my
Shit-Shack DVM). In short, wonce you're *absolutely sure* that the caps
arte discharged, *do* brush them with your finger - this way, you're
expecting nastiness and are prepaired for it. If you *did* make an error,
and didn't do the finger thing, and accidently *leaned* on one of the caps,
you could send some pretty pricey gear flying across the room, and get an
unpleasant memory to boot... Good luck, and, hey - HAVE FUN!
-dim