Anyone remember these? (JMF Spectra)

[pchilson]

JMF Spectra 120-7
120/60 watt 3x12AX7, 4x6L6 amp
Don't seem to find much info or talk about these.
No schematic to be found.
Anybody familiar with these?

[teemuk]

I’m not familiar with those amps but I do know a little bit of history about them. Those amps were made by JMF Electronics, a company founded by Jon Flickinger in 1976. The Spectra-series is from the early eighties. The company was sold to Dean Markley who also introduced Spectra–series of amplifiers. …Solid-state ones - except for the Spectra 60T and 120T models, which were tube amps. I believe there also were “transition” JMF amplifiers that just had Dean Markley badges attached to them.

Dean Markley’s site has some schematics of DM products and with Google you should also be able to find complete (but non-factory) schematics to Spectra 60T from JMF. If you’re into that sort of technical stuff, of course.

Here’s a link to a youtube clip of a JMF Spectra 120T:
http://www.youtube.com/watch?v=yFuveSUaFdo

It’s either the camera, the guy behind the dials or the amp but it – IMO - doesn’t sound too good. In fact, that's one of the worst “tube” tones I’ve heard.

[pchilson]

Ahh, yuh that is terrible. It must be what you stated as the amp does not sound like that mess...hehe
I have seen the history you speak of but that is about all that can be found on the net about these amps. I was hoping some guys who had them would chime in. Thanks though.

[Gtr_tech]

The front panel looks very "peavey".

[bbob]

JMF Spectra 120-7
120/60 watt 3x12AX7, 4x6L6 amp
Don't seem to find much info or talk about these.
No schematic to be found.
Anybody familiar with these?

Yes I do. I have a 12" Celestion in mine. 60T 342 is the number. I bought it in 1983 in Austin Texas.

[Prairie Dawg]

JMF Spectra 120-7
120/60 watt 3x12AX7, 4x6L6 amp
Don't seem to find much info or talk about these.
No schematic to be found.
Anybody familiar with these?

Looks like it's got potential if it can be bought right. Nice glassware and hefty iron...can't go wrong with that.

[bbob]

Looks like it's got potential if it can be bought right. Nice glassware and hefty iron...can't go wrong with that.

I like it. Looks like? You can drag a screwdriver across the magnet twice and it'll pick up a 20 penny nail. I don't know where the wiring diagram is but you can probably find it online.

[Mark Black]

pchilson -

I'm thinking what you have there is actually a 120-T rather than a 120-7.

JMF/Spectra just used a goofy font...

Check the serial number tag to see if the number starts with a 120T (or possibly a 60T).

If true that should improve your odds of getting schematics & such.

Best of luck!

Edit: Dang - I just realized how old the thread is regarding pchilson's last entries. Oh well...

[pchilson]

Well Mark you're right. It is an old thread and the amp is long gone. Regardless, you are correct about the goofy font. It is a 120-T as you suspected by the serial.

[gthorpe]

I own the 40watt tube jmf and it has all the balls you'd want. Very nice amp, very useable vintage sound. I have vintage Sylvania 6l6's in it. Not sure what it came with. Bought it used from my uncle for 75 bucks.

[SuperDistortion]

I have a JMF Spectra 412-e speaker cabinet (4x12 Pyle Driver speakers). It was originally blond tolex but I painted it black. I think each speaker is 60 watts. Any interest?

[Rhodesplyr]

I bought the Dean Markley version of this amp (CD-120) a little over a year ago, not working properly, for $50. I think it had an open plate resistor in the overdrive channel and a bad channel-switching JFET, and it had lots of those tiny Class II ceramic capacitors in it. Replacing a select few of those with mica or film improved the sound. Also, the overdrive channel had a severe oscillation above the range of human hearing that I cured by running shielded leads to that tube socket. Rivets were loose on the 12AX7 sockets and had to be replaced.

Note that it's a hybrid tube/solid-state amp: tube input stages, IC driven volume control and reverb send/return, IC effects send/return, and tube output stage. Mine produces an annoying squeal when you switch it off, apparently an oscillation resulting from the solid state circuits powering down.

The single stock 12" speaker doesn't sound very good, to my taste, with this amp--or with any tube amp I've connected it to. It can produce very loud sounds, but it has a harsh, "ice-pick" tone. I suspect it has some peaks/dips in its impedance curve that tube amps don't like because it sounded OK when I hooked it up to a Peavey Musician solid-state head. Its huge ceramic magnet makes the cabinet VERY heavy.

I'm not wild about the overdrive channel. I think a Mesa Boogie .50 Caliber I worked on recently creates much more musical-sounding overdrive.

My review would be that it's an OK amp using the normal channel into an outboard speaker, but I won't rule out eventually using it as a platform for building something better.

[PapaMidnite]

I have a Dean Markley CD -60 That i picked up at a transfer station [dump] just needed tube sockets and tubes 3 12ax7s and Two 5881s same Blonde tolex cover .The overdive is dated but the cleans are great with a pedal in front