MC250 specific discussion:

MC250 specific discussion:

Postby Pete B. » Sun Dec 19, 2010 2:56 pm

Hey So the MC250 has arrived an I had a chance to mess around with it at the house yesterday.
Thanks to Tracy for a fair deal that went smoothly including safe shipping to my doorstep.
Thanks to Brad for servicing the unit while still in Tracys possesion, and for answering some pre-arrival questions.

From cruising various threads via search I see maybe a half dozen or so guys are using this specific unit, so here are a few more questions.
In "Mono mode" I plug into the Right input jack, and only the Right volume knob contols the output level, but I am still running each speaker in my 2x12 cab individually to the Left and Right output terminals, and they are both cranking equally.
So I have two 4ohm speakers running in parallel for a total of 2 Ohms.
I assume this is like a Twin Reverb when using two 8ohm speakers individually to both speaker-outputs for a total of 4 ohms.
I guess my question is...
In Mono mode, is running two speakers individually to the L/R output terminals respectively, the same as wiring the speakers in parallel inside the cab and running one speaker wire to the bridged output terminal (50W per speaker in either case)?

Also, Is the only way to get 100W output to one speaker to run a wire to bridge the output terminals? The Manual says for a 4ohm speaker to use the Left Terminal Com and 8ohm, and run a wire from the Left 8ohm terminal to the Right 8ohm terminal to "bridge".

What is the deal with "25Volt Line Operation"???... what is that used for?

What is the deal with the "Octal Socket"?

Here is the Manual but obviously I still don't get a couple things:
http://www.berners.ch/McIntosh/Downloads/MC250_own.pdf

Thanks in advance.
I'm sure there will be some other questions.

This thing sounds great!
:cool:
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Last edited by Pete B. on Sun Dec 19, 2010 4:07 pm, edited 3 times in total.
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Re: MC250 specific discussion:

Postby JonnyBoy » Sun Dec 19, 2010 3:42 pm

Sweet Pete, I know you will appreciate it. I love mine.
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Re: MC250 specific discussion:

Postby SarnoMusicSolutions » Sun Dec 19, 2010 10:07 pm

Pete,

I sent you an email. There's a different way you should be running it in MONO according to the manual.


Brad
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Re: MC250 specific discussion:

Postby tigerstrat » Sun Dec 19, 2010 10:47 pm

Cool acquisition, Pete. I was kinda interested too, but minus the means.
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Re: MC250 specific discussion:

Postby JonnyBoy » Sun Dec 19, 2010 11:10 pm

I usually use as a stereo out of fear of hooking things up az backwards, since I have yet to look at the manual about bridging. That sounds right though..... 65watts always seemed plenty for me with the preamp twin.
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Re: MC250 specific discussion:

Postby Pete B. » Mon Dec 20, 2010 1:29 pm

tigerstrat wrote:Cool acquisition, Pete. I was kinda interested too, but minus the means.


T, We'll have to get together to check it out one of these days. I'm sure there'll be an oppurtunity for you to gig with it if you want to sometime.

I am still messing around with running it in Stereo and/or Mono modes (thanks Brad for setting me straight on the hook ups).
I want to try it in Mono into one 15" 200W speaker I use for Pedal Steel. For Steel we use a Volume pedal and typically need that clean headroom.
Bridged this baby should clock ~160Watts... Typical Steel amps are in the 200W range.

So... No On/Off switch and no "On" Light... just plug it in, right?...(the lights dim for a second).
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Re: MC250 specific discussion:

Postby JonnyBoy » Mon Dec 20, 2010 6:05 pm

Ha, I know it is a phantom when it comes to its operation, no lights, no meters, no switch. What were you doing differently from the post above with the mono/stereo speaker hookup?
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Re: MC250 specific discussion:

Postby tigerstrat » Mon Dec 20, 2010 6:57 pm

That's a mighty generous attitude, Pete. I'm getting a touch too much compression from my 60w Mesa, so my eyes are open for the next heart muscle of my rig.

Looked like you had it according to the manual with Left-Com + Left-8, L-8 jumpered to R-8.... that wasn't right?
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Re: MC250 specific discussion:

Postby Pete B. » Mon Dec 20, 2010 7:29 pm

It was incorrect to run it in Mono mode with the two speakers individually connected to the Left and Right terminals.
For Mono mode operation with 2x12's (I am using two 4ohm JBL E120's) I should wire them in paralell inside the cab, and then run one speaker cord to the Left terminal Com and 4ohm, with the jumper to the Right 4ohm terminal. This would give 100W output from the amp, to the Cab which is now a 2ohm load, with the power split to 50W per speaker.

I think I will opt to stay with Stereo operation, or "Dual Mono" as the case may be.
I will probably save the Bridge mode thing for running a single speaker at max power.
I have alot of experimenting to do!

What is the deal with "25Volt Line Operation"???
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Re: MC250 specific discussion:

Postby JonnyBoy » Tue Dec 21, 2010 3:22 am

Yhea I never thought about that, two speakers hooked in series/parallel to the amp in mono is about the same as hooking them separately in stereo to each side. That is keeping 50 watts per speaker either way (really 70-80 watts). Running a 1x12 is where the extra power can come from by hooking it up bridge mono, that will give you the extra love. I liked having the capability to turn down a speaker in my 2x12 if needed, by hooking them up stereo, but look forward to pushing some higher wattage through a JBL E and see the outcome, probably just an ear ache.

I finally got a crate power block on ebay to practice with after I hurt my MC50 by moving it around too much. As durable as these McIntosh's are/were they are pushing 40 years old, and my transformer just couldn't take the moving around/gigging (I suppose, it took a short fall about 4 inches off the dolly, then nothing). I have yet to take it to the Doctor, but it has to be the transformer, a few hundred to fix with original materials I guess (OUCH!)... They are so heavy, and worth carrying it specially by hand to point A and B carefully, in the car alone, in a seat belt even.

I love the tone from the amp, so much to discover too with its style of clipping. I have experimented with different effects between the pre and mac giving me different types of clipping, the boost seemed to be the most versatile to unusable versions, but just my reverb in between added a little punch. Something to play with.
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Re: MC250 specific discussion:

Postby Pete B. » Wed Dec 22, 2010 10:26 am

What is the deal with "25Volt Line Operation"???


I found out that "25Volt Line Operation" is used in places where they need speakers all over the place, like in a church or a school.
Apparently using this method you can run multiple speakers each in a different area up to 2300 feet away from the amp.
I haven't found a link to a really good explaination for this yet but I think that is the basic jist of it.
There are also "70.7Volt Line Operation" systems and here is a link I found:
http://www.soundinstitute.com/article_detail.cfm/ID/101

The other cool thing I discovered about the MC250 is that it sits perfectly on top of a Twin Reverb amp.
So one possible giggig set up would be to sit the MC250 right on top of a Twin Reverb, connect the Pre-Amp tap to the MC250 Input(s), connect the MC250 Speaker output(s) to the the speaker(s) mounted in the Twin Reverb (in my case I have a 15" JBL D130F, but you could run it with one or two 12"s if you have a 2x12 Twin).
You could run it 50W or 100W.
Pretty cool.
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Re: MC250 specific discussion:

Postby tigerstrat » Wed Dec 22, 2010 11:57 am

Pete B. wrote:
What is the deal with "25Volt Line Operation"???


I found out that "25Volt Line Operation" is used in places where they need speakers all over the place, like in a church or a school.
Apparently using this method you can run multiple speakers each in a different area up to 2300 feet away from the amp.
I haven't found a link to a really good explaination for this yet but I think that is the basic jist of it.
There are also "70.7Volt Line Operation" systems and here is a link I found:
http://www.soundinstitute.com/article_detail.cfm/ID/101

The other cool thing I discovered about the MC250 is that it sits perfectly on top of a Twin Reverb amp.
So one possible giggig set up would be to sit the MC250 right on top of a Twin Reverb, connect the Pre-Amp tap to the MC250 Input(s), connect the MC250 Speaker output(s) to the the speaker(s) mounted in the Twin Reverb (in my case I have a 15" JBL D130F, but you could run it with one or two 12"s if you have a 2x12 Twin).
You could run it 50W or 100W.
Pretty cool.


that's what I kinda suspected... or on a military base, or submarine, or aircraft carrier...
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Re: MC250 specific discussion:

Postby Pete B. » Wed Dec 22, 2010 7:49 pm

I'm guessin' the Military stuck to the rack-mountable Macs.
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Re: MC250 specific discussion:

Postby JonnyBoy » Wed Dec 22, 2010 11:01 pm

I am truly not trying to tell you how to set your stuff up, but I had my MC50 hanging off the ground a little and it hit bottom from a two foot fall and now its DEAD, I have learned the best place for those amps are either on the ground or in a rack case on the bottom amongst the wires and junk. I would hate it for you to be in the same problems as me due to gravity and its massiveness. I play a private party tomorrow, and out the 250 will come, also I am going to try Bridge mono this time and see if the tone and clipping is any better.
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Re: MC250 specific discussion:

Postby mijknahs » Mon Feb 21, 2011 10:45 am

JonnyBoy,

How did the bridged/mono go with the 250? Sound good? Less clipping?
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