McIntosh MX112 into Marantz 2252B

[TheoryJean]

Hello! I believe this is my first post in AudioKarma forum. I hope I am posting in the right thread, and I hope I am not posting something that has already been discussed. If so, I apologize for my noobiness.

I recently came across a McIntosh MX112 Solid State Pre-Amp at a garage sale. It has cracked glass and a missing button, and the guy selling it said it was basically for parts, so I negotiated it down to $40 having heard great sound coming from McIntosh products in the past.

I plugged it in and powered it up, and everything turned on. I plugged my turntable into the phono input and then plugged the MAIN OUT into the AUX in of my Marantz 2252B receiver. I hear the music from the turntable coming through at a very very very low / faint volume. The volume knob works and the bass and treble knobs work, but even at everything maxed out, it's like as if the signal were still coming through as a phono (non-amplified) signal, it's that low.

I then plugged the 'TAPE OUT of the McIntosh into the AUX in of the Marantz and I get sound (sounds great but a bit too high gain and volume knob doesnt work). I assume the tape out is only to plug into a tape recorder, that's why it is always the same gain / signal and therefore the signal bypasses the volume, bass, and treble knobs.

Any ideas on why the main out is giving me such a weak signal? Maybe the volume knob isnt working and it's turned all the way down? Any help would be great.

Also, anyone knows where I can pick up other knobs / buttons for this piece as well as replace the glass?

Thanks so much friends! Very happy to hopefully get this thing working (hope im not just getting my hopes up for nothing)

 

[Blue Shadow]

Your third post, previous asking about a gold tonearm upgrade. Hope that worked out.

The tape out is after the amplification but before the controls as you said w/o volume, bass, treble and balance. Correct to use that to aux input.

Could also use main out to aux and expect about half volume on pre would be normal input level to the aux input. Then set the controls on the pre and use the Marantz volume.

But you said your pre doesn’t put out. It needs service or understanding (RTFM issue which I doubt in this case).

For best answers, click the report link in your post, bottom left, and ask a mod to move it to McIntosh forum. They know where to hunt parts, might be able to help you get it working or find quality repair for the unit. Get it fixed and set up right and you have a nice unit to build a system. Maybe by starting with the preamp feeding the Marantz power amp section and use the Marantz for FM, too. Don’t use the Marantz preamp section. But you need those guys to get the signal to come out the main outputs on the 112, first.

 

[TheoryJean]

Your third post, previous asking about a gold tonearm upgrade. Hope that worked out.

The tape out is after the amplification but before the controls as you said w/o volume, bass, treble and balance. Correct to use that to aux input.

Could also use main out to aux and expect about half volume on pre would be normal input level to the aux input. Then set the controls on the pre and use the Marantz volume.

But you said your pre doesn’t put out. It needs service or understanding (RTFM issue which I doubt in this case).

For best answers, click the report link in your post, bottom left, and ask a mod to move it to McIntosh forum. They know where to hunt parts, might be able to help you get it working or find quality repair for the unit. Get it fixed and set up right and you have a nice unit to build a system. Maybe by starting with the preamp feeding the Marantz power amp section and use the Marantz for FM, too. Don’t use the Marantz preamp section. But you need those guys to get the signal to come out the main outputs on the 112, first.

Ah yes, I eventually got the 1200s lookin brand new again.

I took it to a couple guys who barely looked at it and just said "not worth fixing, sell it for parts". However, I don't like that answer, and also want to build off of this unit. $40 is a steal IMO and even if I have to put a few hundred into repairing it, it's a fun project I will learn from.

Just for clarification, my PRE puts out for the TAPE but not the MAIN... interestingly the volume knob while on MAIN does go from absolute kill at zero to increasing to a very, very low volume... does not really sound like it's being amplified.

Why not just plug my turntable directly into the Marantz Pre-Amp section? Is there an advantage of first going through the McIntosh? I assume it is a better pre-amp, and I will get better sound quality, but have not had time to compare the two. Also, why use Marantz FM instead of McIntosh?

Thanks for the help

If anyone else knows what I can do to fix my main, that would be great! Thanks!

 

[Blue Shadow]

Using Marantz for FM gives you 2 stations tuned in at same time and can use an Aux input on the 112. Just using more of the Marantz.

I wrote based on 112 tape out is good, main out is bad. That and using just one preamp in the system, the 112. Don't really want to use two preamps, either one is probably better than using both what with level matching and such. Your choice on TT preamp, Marantz of 112. But if you use the Marantz, the 112 will be only a tuner since you probably only want to use one preamp.

Now to see if there are recommendations for repair between SD and SF. Someone knows

 

[62caddy]

Just be aware you're potentially looking at several hundred in electronic repairs which doesn't even cover the faceplate, bezel and a full set of knobs which will run another few hundred. That's a lot of money for sonic gains that may not even be there.

 

[TSmith8605]

Hello! I believe this is my first post in AudioKarma forum. I hope I am posting in the right thread, and I hope I am not posting something that has already been discussed. If so, I apologize for my noobiness.

I recently came across a McIntosh MX112 Solid State Pre-Amp at a garage sale. It has cracked glass and a missing button, and the guy selling it said it was basically for parts, so I negotiated it down to $40 having heard great sound coming from McIntosh products in the past.

I plugged it in and powered it up, and everything turned on. I plugged my turntable into the phono input and then plugged the MAIN OUT into the AUX in of my Marantz 2252B receiver. I hear the music from the turntable coming through at a very very very low / faint volume. The volume knob works and the bass and treble knobs work, but even at everything maxed out, it's like as if the signal were still coming through as a phono (non-amplified) signal, it's that low.

I then plugged the 'TAPE OUT of the McIntosh into the AUX in of the Marantz and I get sound (sounds great but a bit too high gain and volume knob doesnt work). I assume the tape out is only to plug into a tape recorder, that's why it is always the same gain / signal and therefore the signal bypasses the volume, bass, and treble knobs.

Any ideas on why the main out is giving me such a weak signal? Maybe the volume knob isnt working and it's turned all the way down? Any help would be great.

Also, anyone knows where I can pick up other knobs / buttons for this piece as well as replace the glass?

Thanks so much friends! Very happy to hopefully get this thing working (hope im not just getting my hopes up for nothing)

Regarding lack of output at the main, you might verify the position of the tape monitor and mute switches on the MX.

Also, switch contacts might be oxidized causing loss of signal, so (with the volume most of the way down so you don't suddenly get loud volume if it starts working), you might exercise the monitor switch several times (and then the other buttons) to see if you get a reaction at the main outputs.

If the switches are not the problem, then you (or McIntosh-knowledgable tech) need to dive under the hood.

In addition to the cracked glass and missing button, end plates, bezel around the buttons and feet, your preamp is also missing all of the correct knobs. The pix below shows how it should look. Who knows what electric components have been scavenged from inside. The best bet to find replacement parts, if available, would be Audio Classics. McIntosh themselves or McIntosh Audio might also have some of these parts.

Audio Classics would be a good place for repair / restoration but requires shipping to upstate NY. I don't know of any McIntosh expert techs in the SF Bay Area but I recall reading about a couple of shops in LA. Maybe someone can chime in on that.

I have never heard an MX 112 or a Marantz 2252B so I cannot have an opinion on their relative sound but will say that any comparison of their sound quality cannot be made unless both units are known to be operating properly and to spec. So, before you worry about sound quality, you need to get the MX112 up to snuff (and the Marantz if not already).

62caddy is very knowledgeable about vintage McIntosh and their relative value, so I would direct you back to post 5 above for advice regarding if this is worth restoring. If you decide not to restore it, you might recover your $40 or more selling to someone who does want it for parts.



Here are a couple of links with general information about the MX112:

http://www.mcintoshcompendium.com/Compendium Docs/Tuner - Pre-Amps/PDFs/MX112.pdf

https://www.mcintoshlabs.com/legacy-products/tuner-preamplifiers/MX112

 

[SaturationPt]

The button without a cap is the MUTING button, be sure that it is out/off (and making good contact).

I agree with Caddy, going from a voiced mid-line Japanese receiver to a mid-line McIntosh tuner-preamp likely will show some differences, but whether it is significant or the sound signature that you like is a toss-up.

 

[TheoryJean]

Just be aware you're potentially looking at several hundred in electronic repairs which doesn't even cover the faceplate, bezel and a full set of knobs which will run another few hundred. That's a lot of money for sonic gains that may not even be there.

I'm very much of a DIY guy if anyone can shed some insight. I've been able to repair laptops just by dissecting them and figuring out which components work or not and I had zero experience prior. So anything that I can do myself with youtube academy, I will. If not, I don't mind spending a couple hundred on a professional... the faceplate / glasswork, I will make it custom, I have friends that do it. It won't be original, but that's fine, I love the sound of this thing.

 

[TheoryJean]

Regarding lack of output at the main, you might verify the position of the tape monitor and mute switches on the MX.

Also, switch contacts might be oxidized causing loss of signal, so (with the volume most of the way down so you don't suddenly get loud volume if it starts working), you might exercise the monitor switch several times (and then the other buttons) to see if you get a reaction at the main outputs.

If the switches are not the problem, then you (or McIntosh-knowledgable tech) need to dive under the hood.

In addition to the cracked glass and missing button, end plates, bezel around the buttons and feet, your preamp is also missing all of the correct knobs. The pix below shows how it should look. Who knows what electric components have been scavenged from inside. The best bet to find replacement parts, if available, would be Audio Classics. McIntosh themselves or McIntosh Audio might also have some of these parts.

Audio Classics would be a good place for repair / restoration but requires shipping to upstate NY. I don't know of any McIntosh expert techs in the SF Bay Area but I recall reading about a couple of shops in LA. Maybe someone can chime in on that.

I have never heard an MX 112 or a Marantz 2252B so I cannot have an opinion on their relative sound but will say that any comparison of their sound quality cannot be made unless both units are known to be operating properly and to spec. So, before you worry about sound quality, you need to get the MX112 up to snuff (and the Marantz if not already).

62caddy is very knowledgeable about vintage McIntosh and their relative value, so I would direct you back to post 5 above for advice regarding if this is worth restoring. If you decide not to restore it, you might recover your $40 or more selling to someone who does want it for parts.

View attachment 3090154

Here are a couple of links with general information about the MX112:

http://www.mcintoshcompendium.com/Compendium Docs/Tuner - Pre-Amps/PDFs/MX112.pdf

https://www.mcintoshlabs.com/legacy-products/tuner-preamplifiers/MX112

Hello, thank you for the information. Yes I had assumed the buttons / knobs were not original and that was confirmed when I downloaded the manual. For now, I will keep it that way or have custom knobs / buttons / faceplates / glass made by friends who build this kind of stuff.

I checked to make sure that all the push buttons were in the correct position. I love diving under the hood... but not sure what I am looking for! I guess connectivity from all the switches?

"

exercise the monitor switch several times

What do you mean by this? What is the monitor switch?

I am currently in LA, so if there is someone I can take it to around here, that would be great.

Thanks so much!

 

[TheoryJean]

The button without a cap is the MUTING button, be sure that it is out/off (and making good contact).

I agree with Caddy, going from a voiced mid-line Japanese receiver to a mid-line McIntosh tuner-preamp likely will show some differences, but whether it is significant or the sound signature that you like is a toss-up.

The MUTING button is only to mute the hiss while switching between radio frequencies that is not related to the problem I am experiencing. It doesn't actually mute any signal you put into the pre-amp from any other input source.

 

[eiraved]

I am currently in LA, so if there is someone I can take it to around here, that would be great.

Maybe member @mr_macgee can point you to his tech. Classic Audio may also be around.

classicaudio.com..... Contact Us

 

[62caddy]

I'm very much of a DIY guy if anyone can shed some insight. I've been able to repair laptops just by dissecting them and figuring out which components work or not and I had zero experience prior. So anything that I can do myself with youtube academy, I will. If not, I don't mind spending a couple hundred on a professional... the faceplate / glasswork, I will make it custom, I have friends that do it. It won't be original, but that's fine, I love the sound of this thing.

That's different if you can undertake repairs yourself. Special skills and equipment are needed for tuner repairs so it's up to your discretion whether you want to go that far. If prepared to spend a couple hundred on cosmetics, why not order a faceplate & correct knobs from Audio Classics? The switch bezel might be trickier to source but they do appear on the auction site from time to time. Maybe you can get someone to reproduce it...?

Audio Classics - 016-081

Audio Classic's buys and sells the finest in home audio/video equipment

www.audioclassics.com

 

[TSmith8605]

. . . What do you mean by this? What is the monitor switch?. . .

Sorry, i meant the tape button (called a tape monitor button on some preamps). Push it in and out several times to see if you start hearing output from the main. If the switch contacts for this button have become oxidized over time, the signal might be interrupted and pushing the button a few times would scrape away some of the oxidation.

But given the near total lack of output from both channels, my guess that the problem is not dirty switches and something worse inside.