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Help with Mcintosh MC240

kennyno

kennyno

New Member
I just purchased a mcintosh MC240 ,I have a perfect Mcintosh MA230,
My question is can I use the peramp in my ma230 to run the mc240.
I was thinking mybe useing the tape output on the 230 too the the input on the 240
but dont want to damage it . or is there a better way?
New to this have no one to ask .
thanks
 
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doesn't look like it has a preamp out on it. i know if you use the tape-out's you'll lose out on any volume control, and most likely the tone controls too.
 
Until you find a good preamp for the 240, you "could" use the tape outs...BUT...turn the gain controls on the 240 all the way down and then after a few minutes SLOWLY turn the left and right gain controls up til you have a decent volume to listen to. It would be a good idea to turn the gain controls back down when you are finished with your listening session and turn things off...amp first.

It's not ideal but it will get you listening until you can get a proper preamp.
 
kennyno said:
I just purchased a mcintosh MC240 ,I have a perfect Mcintosh MA230,
My question is can I use the peramp in my ma230 to run the mc240.
I was thinking mybe useing the tape output on the 230 too the the input on the 240
but dont want to damage it . or is there a better way?
New to this have no one to ask .
thanks
Click to expand...

With an adapter cable, the headphone jack can be used. Gain controls on the MC240 will allow this without overdriving the amplifier.

Are speaker outputs disconnected of the MA230 when headphone jack is connected? If they do not, it might not be a bad idea to connect a pair of 1w 100 ohm resistors across the 230's output terminals to prevent it from oscillating.
 
Thanks Ill try that as a temporary solution, but I would be able to use volume and bass ,treble on the 230 pre amp
Thanks for help
 
kennyno said:
Thanks Ill try that as a temporary solution, but I would be able to use volume and bass ,treble on the 230 pre amp
Click to expand...

If you couldn't, the jack would be rather useless for headphones...
 
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Do all the tubes (6L6) in the mc 240 have to be the same brand .
I see them sold as sets but only need 1 of them to get my new/old 240 up and running.
have 3 that are mc and test good but I only want to replace one with something else for now ?
 
I used two Peerless speaker transformers connected to my Ma 230 to the MC 60 amps. I think I used a 8 watt tap which would knock down the 30 watt output on the 16ohm tap down to appox. 2.7 volts. You could do the same thing with resistors. Place a 8 ohm resistor to load the amp and then a 10 to 1 voltage divider and you should be good to go using the twin amp inputs. The transformer were rated +/- 1 30 to 16,000 hz as I remember. I Had to ground the MC 60's as the transformers isolated the the amps from each other. That was 50 + years ago. Time flies when your having fun. Wonder what happened to my MA 230. Maybe its the one you are using.
 
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kennyno said:
Do all the tubes (6L6) in the mc 240 have to be the same brand .
I see them sold as sets but only need 1 of them to get my new/old 240 up and running.
have 3 that are mc and test good but I only want to replace one with something else for now ?
Click to expand...

Because of the Unity Coupled circuit, output tubes do not need to be matched.
 
62caddy said:
With an adapter cable, the headphone jack can be used. Gain controls on the MC240 will allow this without overdriving the amplifier.

Are speaker outputs disconnected of the MA230 when headphone jack is connected? If they do not, it might not be a bad idea to connect a pair of 1w 100 ohm resistors across the 230's output terminals to prevent it from oscillating.
Click to expand...
If you're not hooking the MA230 to speakers you could pull the 7591s. No reason to waste tube life.
 
nj pheonix said:
If you're not hooking the MA230 to speakers you could pull the 7591s. No reason to waste tube life.
Click to expand...

I cannot speak specifically to this case but in the past, Terry has generally been adamant that equipment never be operated with less than its specified full tube compliment.

Second problem is that the headphone output is taken off the main amplifier output via a step down transformer. If the tubes are out, there'll be no headphone signal.

FWIW: I've run an MC2505, MC240 and MC30 off the headphone jack of the MAC1500 which is very similar to the MA230. It works perfectly and is by far the simplest and most elegant solution for running outboard amplifiers from a MA230 or MAC1500 and without the need for making any special grounding provisions, etc.

Output impedance at this jack is 600 ohms which can easily run a slew of amplifiers.
 
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Ok thanks for the lesson. I had a 230 several years ago but never had the need to go that way. I was thinking it came off the preamp.
 
OK I have another problem, I powered up my 240 for the first time.
Which was sold as working as new. The 6L6 second from the front of the amp lit up
like spot light and went out . When I checked the tube the center post of the tube was gone
and the fuse was blown. After removing the bottom cover of amp I found the Thermistor
was broken apart also.
My question is could the broken center post of the tube have caused the fuse to blow and the Thermistor to break apart.OR do you think I have bigger problems with my eBay jewel ?
I am taking it to a qualified tech to be gone through .
 
While tubes are glass (they're reasonably robust, that is , traveling well packed this shouldn't become an issue in transit) and nothing is impossible, I'd be thinking you have another issue. I imagine your tech shouldn't have too much trouble finding issue.
 
I missed the broke keyway thing last night. I think damacman is spot on.
There's only one right way for that tube to go in. The bad news is that tube is likely toast now. The good news is the amp is" probably " ok except for the fuse and the in rush limiter. Also the design doesn't require matched pairs so you only have to buy one tube , not a pair. Good luck.
(I really should refrain from commenting when I'm in a rush or half asleep:dunno:)
 
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