McIntosh ML-1C upper mid range issue

[Laricc]

I recently got a pair of McIntosh ML-1Cs and the upper midrange on one of the monitors creates a nasty buzzing sound around 3k-4k Hz. When I got these speakers I noticed that the sound and found that the upper midrange was pushed. I used the vacuum trick to fix it, hoping it would fix the issue. In the end, nothing changed. I was wondering if there are any solutions to fix this issue.

The first image is a picture of the one that is operating properly

The second is of the one that has the buzzing problem. Another thing I noticed is that that it appears to be glued back down.

Thank you for your time.

 

[homebrew]

It's possible you have damaged voice coils on the drivers. The only way to tell is remove the drivers and separate the dome and associated coil. Inspect for burn marks or other signs of abuse. If the voice coils are damaged, the drivers may be able to be rebuilt. (If so, re-do both mids for the sake of continuity.) If you contact McIntosh, they might be able to recommend someone to do the work.

 

[Laricc]

It's possible you have damaged voice coils on the drivers. The only way to tell is remove the drivers and separate the dome and associated coil. Inspect for burn marks or other signs of abuse. If the voice coils are damaged, the drivers may be able to be rebuilt. (If so, re-do both mids for the sake of continuity.) If you contact McIntosh, they might be able to recommend someone to do the work.

"The voice coils were "buzzed" into the correct centering. To do this, the voice coil is driven by a power amplifier connected to an oscillator. If the voice coil is rubbing, a buzzing sound could be heard. The dome/coil assembly is then shifted around until the buzzing stops. This has to be done before the adhesive dries. Hopefully, the dome is then well centered. Several other companies have used this method of centering."

Source: http://roger-russell.com/driversm.htm 1-1/2" Dome 036-016

I ended up finding this article after doing some research, along with a schematic for the ML-1C (http://roger-russell.com/ml1cservice.htm).

 

[Mike Gibson]

I would email Roger Russell at www.roger-russell.com as he designed them and has updates and would know how to fix it.

 

[twiiii]

You might find a replacement at Audio Classics if Steve is in a good mood or on e-bay. Audio Classics has an updated crossover you can add with new super tweeters and mid tweeters that handle more power than a ML-2. Which is twice as big as your ML-1. You night find a replacement on E-bay but you will have to bend over and smile.

 

[Laricc]

You might find a replacement at Audio Classics if Steve is in a good mood or on e-bay. Audio Classics has an updated crossover you can add with new super tweeters and mid tweeters that handle more power than a ML-2. Which is twice as big as your ML-1. You night find a replacement on E-bay but you will have to bend over and smile.

Can you send me a link to the updated components?

 

[Laricc]

UPDATE:
So far I've done some more research on russel's site. I ended up pulling out the midrange to get a better look at what was wrong with it.

To start off, I noticed that the top edge of the dome's surround was at a slant. This is the portion that I noticed the buzz was coming from. The other thing I realized is that the dome may have been removed at some point. (It's been glued back down with what I can guess to be gorilla glue) I haven't really tried to mess with smaller drivers, so this is new territory for me. From here the only solutions I can see are to look out for 055 midranges, alternative aftermarket midranges, or to do some surgery to fix the surround.

One other thing I noticed, was the fact that this midrange is nothing like the 016 or 055 models, which is leading me to believe that this is either some aftermarket design or a repurposed 016. I'm not too sure about a lot of this stuff, or what would be the best option. Any suggestions?

@twiiii I poked around on https://www.audioclassics.com/ but I found nothing relating to replacement tweeters or crossovers.

http://roger-russell.com/driversm.htm#d055
http://roger-russell.com/driversm.htm#d016

Thanks.

 

[A400]

The slant you describe and show means the voice coil may be on an angle compared to the gap. There's a good chance this will allow the two to make contact and buzz.

Can you correct the slant by carefully pressing on one side of the diaphragm? If so I would try to get the slant corrected; heat the diaphragm with a hair dryer or similar gentle heat and then cool. This may restore it to the correct shape and is low risk, non-invasive surgery . An important detail here is to get the dome in the correct position compared to the good driver (i.e. not pressed down too much - you want it in the neutral position). This may require pulling up on one side rather than pushing down, which could possibly be achieved with sticky tape or similar if the dome material is robust. Heat can sometimes be used to remove dome dimples too but may be difficult without accessing the rear of the dome, so probably best to leave well enough alone. Good luck.

 

[twiiii]

I found some thing the other day. Here is a pair of ML-1's with Roger Russels, the original designer s up date. Call Audio Classics for info. It aint cheap but it makes a ML-1 out perform a ML-2 down to 40 HZ. There is a reason for having two woofers.

 

[Laricc]

@twiiii Ah thanks. That definitely would be a solid deal and I may take a look...The only problem is how much

I was thinking about replacing the midrange, tweeter, and crossover since I have access to a workshop, and since I got a DATS sometime ago. The only thing is I'm a newby to building speakers, I only just got serious about it during the past months.

So far I'm up in the air about what I want to do. I saw a pair of 016's being sold, but after reading up a lot on the 016's from roger's site, along with a few other forums it's made me hesitant.

 

[twiiii]

Call Steve maybe if you buy the components and install them your self saving many $$$$$$$

 

[Laricc]

@twiiii I ended up calling them, I got a response but it seems that they don't have the components anymore

 

[Laricc]

@twiiii I may have figured out the midrange and tweeter used

I could be wrong, but the dome is about 2 1/8, which is roughly the size of the dust caps on the 8" midrange woofer. (at least on mine.)

After looking around online I came across this on Parts Express.

https://www.parts-express.com/morel-mdm-55-2-1-8-soft-dome-midrange--287-020

At this point, I'm just eyeballing it and guessing; but if morel midranges/tweeters were only used, the best conclusion I can come up with is it could be one of these three tweeters.

https://www.parts-express.com/morel-mdt-39-1-1-8-compact-dome-tweeter--277-035 - I got a good feeling it's this model.

Especially after seeing the reflective dome.

https://www.parts-express.com/morel-mdt-22-1-1-8-soft-dome-neodymium-tweeter--277-062
https://www.parts-express.com/morel-mdt-12-1-1-8-neodymium-tweeter--277-060

If this is in fact the sets used then man, at least that's half the battle!

http://www.roger-russell.com/ml1cpg.htm#ml1cspecs