JMF Spectra 315 Amp Info Wanted

Basslice · #1 04-04-2011, 08:48 AM

Yesterday I inherited a JMF Spectra 315 Combo Amp and matching Spectra EC-315 cab (along with a sweet Fender Jazz V - American Standard) from a good friend that decided he wanted to get rid of stuff he had in storage (middle aged with kids - not in need of $$). I know little of the amp and he brought it over last night. I had to force him take a few hundred for the Fender (a dream deal for me), but I told him I didn't want the amp. He said to keep it or try to sell it. I really don't need it. It looks like new, but it is at least 25-30 years old.

The back of the JMF Spectra 315 - claimed 250W of solid state power. I am dubious of such claims on amps made in the 80's as just about everyone in the business were a pretty much a pack of liars back then in regards to power. I would guess it may well consume 250W at peak full power, but guess it can only output half of that in terms of continuous sound power at a reasonable level of quality.

It was made in Salinas, KS. Apparently, the company was sold to Ernie Ball in the 80's. I have never run into any of their gear before. I read somewhere that they made one decent tube guitar amp back in the day. This bass combo with an accompanying 15' cab is a real unknown to me.

I plugged it in and the pots were dirty, but it sure didn't sound too loud. It was quiet at low volume and then the solid state started farting at high volume (9/10). It has a switch labeled compressor that I suspect is more like a limiter to prevent too much clipping by the preamp. I have an Ampeg V4-B that is louder at 4/10 and is only rated at 100W. It is the whole tube vs SS I argument that I don't want to get into right now. Not sure what kind of drivers the JMF is loaded with. The combo and the matching second cabinet are loaded with 15" in a folded horn configuration. The cabs are not that deep.

Anyone every own or play one of these? It probably is not worth much.

Dbass10 · #2 04-04-2011, 09:04 AM

Pretty neat! I don't have a JMF but what I do have is a Dean Markley Spectra 315. It was my understanding that Dean Markley took over producing the JMF line for a few year I think in the late 70's-early 80's. I bought mine used from a music shop back in 87 and still have it today. You are right about the compressor switch is it more of a limiter. I'm a little surprised about the volume. On mine I usually put the volume up to about 7 and then control overall volume with the master much beyond 5 and the limiter starts kicking. I would think having the other 15 though that it should be more than loud enough for most music. (still might not be comparable to 100 tube watts though). I've beat the hell out of mine and it keeps right on ticking best $200 I've ever spent on gear. Also on mine one of the inputs is padded even though it's not marked, yours may be as well. Not sure if that could explain the volume thing. There are probably a few other folks around here that have some info on these. I know when I was looking up the Dean that I couldn't find much. They probably aren't worth much but for a practice set up it ain't bad. All that said I think mine sounds pretty decent for what it is and if I want a little tube tone I just put my multidrive in front and it works well. Good luck finding more info!

Basslice · #3 04-04-2011, 09:14 AM

Quote:

Originally Posted by Dbass10

t was my understanding that Dean Markley took over producing the JMF line for a few year I think in the late 70's-early 80's..... I'm a little surprised about the volume. On mine I usually put the volume up to about 7 and then control overall volume with the master much beyond 5 and the limiter starts kicking.....

Thanks for the reply! I think you are probably right about Dean Markley vs what I said about Ernie Ball. Also, I only had it on for 10 minutes and was playing the new Fender Jazz through it in my basement. The Fender needs new strings and I am not familiar with the setup and controls, so I was not really getting a good tone. I guess I should haul the mess over to where we practice and try it through one of my favorite basses in front of the full band. I feel bad not offering my friend $$ for it since he practically gave me his mint condition bass...

Dbass10 · #4 04-04-2011, 09:39 AM

If your amp is set up like mine I believe the left most input is for passive and the right is for active basses (don't quote me). The volume controls the input volume (gain without the tubes) and the master the overall. The Eq controls should all be +5 to -5 boost or cut. Mid-shift controls what freq is cut or boosted (really key to this amp I think). I would start out with everything "flat" = 0 get up to a reasonable volume and tweak from there if necessary. I've never been able to run mine with an extension cabinet but I would think given the volume of the one that adding the extra surface area would really boost the output. It ain't the most modern sexiest or lightest thing in the world but is should get the job done! Enjoy!

crossroadguy · #5 05-28-2011, 09:11 PM

Amp was a 120 watt single 15. 8 ohm internal meant 60w.OEM speakers were made by Pyle. pots get REALLY dirty, use caig labs D-5/deoxit sparingly. the toggle switch on the front panel turns off the anti clipping circuit, but the front end will clip if the master is below 10.
Antiques from Kansas.
Both the amp and I.