ampex 620

jmligt · Post by **jmligt** » Mon Nov 14, 2005 11:35 pm

I recently aquired an ampex 620. My dad picked it up at a flea market for me for $5. The ampex 620 is an amplifier/speaker combo built into a little suitcase. The power cord was missing so I wired up another one I had laying around. Unfortunately I plugged it in and it doesn't pass audio. It powers up, the tubes glow, but no sound when I plugged a guitar in. The speakers crackle a bit when I plug and unplug the guitar and there is a hum when nothing is plugged in. Any ideas on what the problem could be? Bad tubes? Is it worth fixing? Here's a link to the schematic: http://ampex.hughescatalog.com/620/Schematic.pdf to give you an idea on what is in the thing. I have an old RCA tube power amp that I love and wouldn't mind hearing this thing.

joel hamilton · Post by **joel hamilton** » Tue Nov 15, 2005 7:39 am

That suitcase is the same one that the 601 recorder came in, so the electronics for a 601/602 mic pre would fit in there.

I havent tried the speaker/amp combo thingy, but it could be fun for something.

analogcat · Post by **analogcat** » Tue Nov 15, 2005 8:28 am

I've got a couple of these, they sound great. I did need to get them both re-capped.

You aren't plugging the guitar directly into the front are you? That 1/4 inch is an out as far as I can tell. The input is an RCA on the side, plug a CD player into that and try it again.

pulse_divider · Post by **pulse_divider** » Tue Nov 15, 2005 11:56 am

I have one of these and love love love this amp. I have a couple of other small tube amps for recording and this is my favorite.... instant classic rock.
I definitely think it's worth getting fixed.
But yeah, the input is the little RCA job on the side above the power input.
I think I need to get mine recapped as well, it sounds great but hums a bunch.
Thanks for the schematic link.

jmligt · Post by **jmligt** » Tue Nov 15, 2005 5:32 pm

Thanks for pointing out my idiocy. I haven't been made out to be an ass in public for a long time. Looks like I'll be making up a cable or wiring a 1/4" jack into this thing. Look forward to hearing it now. Thanks for your help....

analogcat · Post by **analogcat** » Wed Nov 16, 2005 5:06 am

It took me a while to figure it out. The campanion piece, a 601 tape recorder, has a 1/4" out, 1/8" in. So I thought that the speaker would also be 1/4". I didn't even recognize the old RCA and tried plugging 1/8" into it.

It's line level, so I'm not sure you can plug a guitar into it without going through a pre-amp first. Never tried. I plug into a TLA Pre (all it's good for) then that into the amp.

pulse_divider · Post by **pulse_divider** » Wed Nov 16, 2005 8:40 am

It works great with guitars straight in... you just need a 1/4" to RCA cable.
I love it on guitars. My friend's favorite guitar is a crappy old hollowbody Silvertone and it sounds amazing with this amp, though I usually run it out to an external speaker.

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