McIntosh - Hints and Kinks

[Paul K]

Phono eq can be a problem depending on the cartridge.

Not a problem with the previous unrestored piece...

 

[dewickt]

Dirty filter switches and loudness control come first, next has the 110 been updated with new capacitors ?? If the phono input has the shorting plugs in the wrong inputs it can be loaded incorrectly, and finally if the phono in is shorted and the gain run to the top do you have humm, this could be a bad filter capacitor.

 

[Paul K]

Dirty filter switches and loudness control come first, next has the 110 been updated with new capacitors ?? If the phono input has the shorting plugs in the wrong inputs it can be loaded incorrectly, and finally if the phono in is shorted and the gain run to the top do you have humm, this could be a bad filter capacitor.

Terry it's a complete rebuild - everything is new - or has been replaced - new caps. resistors, the lot - all the way to the new RCA jacks at the back - Modafferi did this and apparently has gone through it - 10 days on the bench...
I am wondering coming from you, a man who has restored these things - does the bass come in a bit more fully after a few weeks breaking and burning in?

Thanx

 

[MX117.MC7150]

Don't forget that cartridges also require some break-in, as well, if yours is new. Do you have another cartridge you can try for comparison? You might want to let it run on a CD with good bass on repeat for a couple of days (doesn't have to be loud) to see if that helps.

 

[Paul K]

Don't forget that cartridges also require some break-in, as well, if yours is new. Do you have another cartridge you can try for comparison? You might want to let it run on a CD with good bass on repeat for a couple of days (doesn't have to be loud) to see if that helps.

Cart is broken in...
Will try to play program material with good bass for a while...

 

[Paul K]

Ok still kinda waiting on some advise here...
Anybody have any experiences with bass lacking on a restored 110?

 

[wingzam]

Ok still kinda waiting on some advise here...
Anybody have any experiences with bass lacking on a restored 110?

Sorry I can't offer a suggestion,but was wondering if Audio Classics has given you any support on this problem.I have an early model MX110 that I'll be having worked on so it would be good to know if there's a pitfall I need to be aware of.
Good luck

 

[dewickt]

Watch out for amplifier loading, a MX110 will have bass roll-off if feeding an amplifier with a low impedance input, it likes 10K and above.
Try the tape output (fixed level) and see if it sounds different.

 

[Paul K]

I will...
Understand however that this is the second MX110 that has been in the system.
The previous one was unrestored and both have fed into an MC 240...
My main question is will burn in of a totally rebuilt unit yield better bass response in the lower octaves?
It's been on for 30 hours...

 

[Rich Andrews]

Sometimes it takes a little more digging to get to the root of a problem. If it were me, I would test by substitution.

Since you have a MC240 amp, feed it from a CD player that has variable output. Even a portable will do.

 

[Paul K]

Perhaps I wasn't clear about the situation at hand...
I had a non restored 110 in place until Thursday...(a friend's)
Same day the rebuilt by Modaferri 110 comes by UPS...it's hooked up and all the tubes check out...mostly the same in the key areas.(12AX7, 6U8's)...and now I am finding the bass without depth at the lower octaves making the music sound undynamic and without oomph...
Knowing that most if not all the caps were changed I am wondering if that is the problem and I need to play it for 200 hours or whatever...
There is nothing wrong with the rest of the system...

 

[Rich Andrews]

There should be no break-in time. I would contact the seller of the MX110 and complain.

 

[rye667]

mc 30 mod

mc30 component layout

thanx paulram for the useful layout! very nice!

and now for all of you curious peeping toms, here come some pics of my nude breasts. before surgery and after.

after changing diodes to 1n4007, soldering in the missing 820k (r23) and the 9.1k resistors i come to a bias of about -41.8v for both mc30s.

cool isn't it?!

rye

 

[tblob]

Watch out for the sand block 5 watt resistors, the type used by McIntosh are also used a fuses, they are designed to open when hit with an over current condition, this is a safety feature designed into the part.

The 3.6K ohm sandblocks on my old MC2300 driver cards are IRC, PW-5 series, and I recently ordered some new emitter resistors directly from Mac Parts, and they were the same, IRC PW-5 series sandblocks, with late 90's date code.

BUT...the data sheet for these resistors from IRC say very promenently at the top of the page "General Purpose Wirewound Resistors" and they don't mention anything about any special features.

Are all IRC PW-5 series sandblocks created equal?

BTW, Mac Parts is now also issuing an NTE175 in place of 2N3738

 

[Rich Andrews]

I see no issues using the wire wound resistors Mc shipped. The sand filled wire wound all perform the same when overloaded - They go open without any smoke, flame, etc. There will be a little smell but that is all.

 

[Mike Gibson]

This thread is for modifications to McIntosh equipment. All I ask is that they be tried & tested changes before you post them. Thanks.

 

[dewickt]

How not to Mod/update

I don't mind helping out as long as I have time, just don't bite off more than you can handle. Good soldering practices and neat workmanship count with McIntosh, they were works of art when new, lets keep them that way.

 

[c_dk]

Study the schematics to learn how the variious gain stages work and shape the spectral balance of the sound and create spurious noise.

Study the convoluted reference grounding and shielding (or lack there of) used as best pre 80s practices and implement new solutions.

Beware of marketing department engineered products as solutions.

 

[Rich Andrews]

C22 mod - extended HF response

To extend the HF response flat to about 22 KC remove C19 and C20, 33 pf caps.

In stock form my C22 started to roll off at about 18kc.

 

[Rodeodave]

When working with the turret boards in classic McIntosh amplifiers, be sure to mount new parts (usually resistors) to the same specs as McIntosh engineers did.

A sturdy mechanical connection of a part ensures a secure and conductive solder joint later. It's not hard to do, looks neat and is superior in function.