[strumminsix]

So I know a few folks on this board have these (150/80/40) amps. What can ya tell me about them?!

I have a 150 coming in this week that I am super excited about! The previous owner/seller said the following:
- works great
- super reverb
- speaker (DM's Magnum) is solid
- loud as hell but still sweetly clean
- when engaging the FET on the clean the volume drop is significant

What speaker is in yours? Have you tested others out? I'm curious about this one since I have nothing in my arsenal capable of handling anything near 150 watts.

[strumminsix]

FYI: For service these guys are the ones DM recommends:
http://www.upscalemusic.com/services.php

[mkaufman]

I replaced the speaker with an EVM-12L.

I used Upscale to rehab mine, however, it came back with an issue. It worked fine if it wasn't mounted in the cabinet. The vibration was causing a cold solder joint to intermittently malfunction. Jonarobb fixed it for me. If you need, I have the schematic.

Yes, using FET reduces the volume, however, it's much cleaner as it removes the tube from the circuit.

mk

[strumminsix]

I replaced the speaker with an EVM-12L.

I used Upscale to rehab mine, however, it came back with an issue. It worked fine if it wasn't mounted in the cabinet. The vibration was causing a cold solder joint to intermittently malfunction. Jonarobb fixed it for me. If you need, I have the schematic.

Yes, using FET reduces the volume, however, it's much cleaner as it removes the tube from the circuit.

mk

That is very weird, MK. Seems odd that it would happen like that but I guess it makes sense....
Very, very cool, of an offer MK! I'd appreciate the spec very much!

I will likely ship it off to Jonarobb to do a good 1-over after I play with her a bit!

Questions:
Do you really think she is putting out 150W?
Do you like the EVM12L?

[jonarobb]

Yeah, I ended up having a really good time working on MK's Dean Markley. Like any solid state or hybrid unit, I took my time troubleshooting the power section. At the time he had just received it back from another shop and I was terribly surprised they had missed 2 crucial problems. In Michaels, the staging or biasing resistors for the output transistors had come loose from the PC board. These are the big .33 5W Ceramic resistors you see in a lot of solid state output sections. Once I took care of that I was able to scope the amp and get full power with an audio signal generator.

The preamp is another crucial area on this particular Dean Markley. The tube/fet hybrid is exactly the same as the old Acoustic Control Corporations Model 165. The small signal fet transistor on Michaels amp was visibly cooked out, as were the rest of the passives nearby. I had scored some beautiful old RCA JAN transistors from previous work on Acoustics. After rebuilding the fet network in the preamp this amp really sprang to life.

The next problem was Michaels speaker. The original Dean Markley speaker was woefully underpowered and the voice coil had frozen. We replaced that with a like new Electro-Voice EVM 12L Series II. This I felt was a great match for the amp due to how efficient it was. The EV does an excellent job of just reproducing tone without imparting any coloration of its own. It gives you a true picture of what your amp is capable of.

I felt that both the fet and tube front end were equally tasty and offered distinctly different options as far as dialing in a sweet guitar tone.

A very cool amp and I am grateful to Michael about the kind words working on it. Ilve since taken on a few others on recommendation. I welcome select solid state work as long as they are unique pieces such as this.

Thanks again,

Jonarobb(Jason)

[JohnDExtonPa]

Anyone have any insight on this? I have a Dean Markley RM 150 DR Combo. Two Speaker Jacks on back simply labled "Speakers". One jack connects to the single combo speaker ( 8 ohm) and the other Jack is open.

I have a 1960 Marshall Cabinet with these availible ohm choices: 16 (mono) 8 and 4 (I think Stereo). Can I unplug the currect speaker jack to the combo and siply run a speaker cable to the 16 ohm Mono jack and be safe? Or am I asking for a blown amp by trying that?

[mkaufman]

I've run mine using one connection to an 8-ohm speaker and using two connections, each to an 8-ohm speaker.

According to the manual: "the jacks are wired in parallel, and either jack may be used for single speaker connection. The minimum TOTAL impedance of all speakers connected should not drop below 4 ohms."

So, you should be able to connect (2) 16, 8 or 4 ohm speakers in parallel.

Yes, you can disconnect the current 8-ohm speaker and connect the Marshall can using any of its connectors.

mk

[JohnDExtonPa]

I've run mine using one connection to an 8-ohm speaker and using two connections, each to an 8-ohm speaker.

According to the manual: "the jacks are wired in parallel, and either jack may be used for single speaker connection. The minimum TOTAL impedance of all speakers connected should not drop below 4 ohms."

So, you should be able to connect (2) 16, 8 or 4 ohm speakers in parallel.

Yes, you can disconnect the current 8-ohm speaker and connect the Marshall can using any of its connectors.

mk

The 1960 Marshall Cabinet has a total of 4 speakers built into it.
The crossover on the back of the Cabinet has a 16 ohm jack as well as the 8 and 4.
So I guess it is safe to unplug the current speaker and run a speaker wire to the 16 ohm connector? There will be 4 speakers total in the cabinet but @ 16 ohms I guess it is safe? (This ohm thing is always a bit confusing).