Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #129702  by Tbrogit
 Sun Jun 30, 2013 4:15 am
So Ive setup my Resissue Blues deluxe into the MC50. Couple of immediate evaluations. Dead quiet for one. Much more articulate in the response and especially in the bottom end where I always thought the stock power section was a little too loose for my taste. Still sounds like the Blues Deluxe as expected. Just different qualities as described. I will say I was disappointed in the overall volume. I set the Mc50 at 12 and also in its maxed out position (5 o'clock) and really did not think it was very loud. Certainly not as loud as if I was driving the tubes. I wanted to keep the Clean section of the Blues around 5 but played around in the 7 range for more volume. My take is the pre amp should be in that range for a good clean sound and the MC50 should drive the volume. Anyway just passing on some observations. I cant imagine any modifications will improve volume. Maybe tone but volume I would think it is what you got. Any thoughts?
 #129703  by czyfingers
 Sun Jun 30, 2013 4:56 am
My initial thoughts are either your preamp signal isn't very hot or the mc50 is performing up to snuff. I use a DSR into an mc50 driving 2 K120's and with the pre at 4- 4 1/2, the 50 at about 3/4, and the guitar at about 6 its very loud. Loud enough to cut through a band at a reasonable volume. My guess is the pre out signal is on the weak side. I'm assuming you're using the pre out on the top panel. I'd take a look at the circuit and see just how pure that signal is and where it's coming from. Generally speaking, doing the preamp tap as a mod, Jerry style creates a pretty darn hot signal.
 #129706  by Jon S.
 Sun Jun 30, 2013 6:12 am
I've posted before that my MC50 is so loud I haven't even used it yet above 1/3 even with my band (this is driven by a Fyd preamp on 5 into an E120). You wrote:

>> I set the Mc50 at 12 and also in its maxed out position (5 o'clock) and really did not think it was very loud. Certainly not as loud as if I was driving the tubes [of the Blues Deluxe].

Having also previously owned a Blues Deluxe, there is no doubt to me your MC50 is not working properly. When I bought mine, I forwarded it on for servicing before I even turned it on. 40 years wreaks havoc on caps and sometimes other components.

When and where did you last service yours?
 #129708  by Smolder
 Sun Jun 30, 2013 7:08 am
Agree - something is wrong. I run the SMS at about 10 o'clock with the MC50 at about a third... single D130 and it's friggin loud. Cranked up it's louder than my 50 watt plexi with a 4x12.

Don't under estimate the importance of good preamp tubes. A 12AX7 has potential gain factor of 100, but that doesn't mean yours do. I have a few (my best ones) that are in the upper 90's, but a lot of them re lower and as a result are less loud. If you run new manufacture pre's, and the gain factors are often around 60-80 and early in the circuit that can have a pretty big effect on overall volume, but I suspect something else is in play as well (by the way this often explains the apparent difference in volume people notice between the two channels of blackface and silverface amps).
 #129709  by ccw3432
 Sun Jun 30, 2013 8:36 am
Are you running from the preamp out jack into the MC50? Are you using the correct cables? TS (not TRS) to RCA.
 #129712  by Tbrogit
 Sun Jun 30, 2013 11:14 am
Thanks for the responses. I'll have it serviced by Pat when I can get it out there. Im running from the preamp out on top plugged into a 1/4 to RCA jack. I just got the thing so no servicing yet but its on the agenda.
 #129729  by Grant
 Sun Jun 30, 2013 9:48 pm
I will also say that my MC50 was extremely loud
 #129742  by tigerstrat
 Mon Jul 01, 2013 11:17 am
Speakers used? Crucial bit of context missing from this thread.
 #129746  by Winterland
 Mon Jul 01, 2013 2:10 pm
I had one that had a similar issue here is what I was told:

The problem was that someone cut all the wiring taps from the output transformer (autoformer) except the ones they "thought" they were going to use (the 8 ohm tap only was connected). The problem with this (I was told) is that ALL the taps need to be connected for the transformer to work properly.
It's not like tube amp output transformers where you can just hook up the tap you're going to use and leave the others "floating"
(unconnected). Once all the connections were connected to the correct location on the schematic, then the amp worked properly. No distortion and the full tone was back to how it should be

Let me know where you get your serviced. I need to get my other one fixed.
 #129751  by Tbrogit
 Mon Jul 01, 2013 4:20 pm
The speaker is a EV12L. Very capable speaker. Im going to send it to Pat Hickman when I get a chance.
Maybe I'll try to attach a sound clip.
 #129820  by JonnyBoy
 Wed Jul 03, 2013 1:17 pm
As mentioned before, it's prolly the amp needs recapped. It should be louder than you need. I use an MC100 that is beyond loud at 1/3 up even using my fender HRD 3 as a pre.... If you are inclined to do so doing plate resistor swap and a tone stack upgrade will make the pre sound much better.