Joining the Mc owners club! Have some general questions...

Chinorlz

New Member
Good evening everyone!

Been reading a bunch of threads on Audiokarma for quite some time and the breadth and wealth of knowledge on here continues to amaze me.

In no small part based on the reading here, over the last two months I've slowly assembled my audio setup:

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A pair of MC30s powered by a MX110Z with everything running to a pair of Kauri wood rebuilt Klipsch Heresy's w/updated crossovers, Crites woofers and K77M tweeters.

The MC30s were restored prior to my purchasing and look great cosmetically. Per the original seller, both have new filter caps, new bias rectifier and bias cap. Both had 820k bias resistors replaced that had change value to 950k. Both check on MC load resistor at 38 watts output at <.5% distortion and 1 watt .05%. All measurements made with HP 339A Distortion Analyzer.

The MX110Z was also restored and all tubed checked with the bad ones replaced.

hard to see in the quick photo (table is pending so everything is currently on the floor haha) but I've got a Schiit DAC linked to an Apple Airport Express to pipe in my digital audio as well. Technics MK5 (I used to be a DJ) for my vinyl needs to be connected as well.

So for the questions for the pros:

1. When I power the amps up, there is a light crackle/hiss in both speakers and one speaker picks up a spanish radio station. After some shuffling/trading of wires, amps etc. It seems like the radio station signal is coming from one of the MC30s. What could be the etiology? Something to dig into?

2. If I'm playing the music even at reasonably low volume (background music) the hiss/crackling can't be heard though... is this normal or should it be completely silent?

3. Based on the MC30 restoration details from the original seller, is there anything else I should be checking out/changing? I can do some simple soldering if there is anything else critical that needs changing.

4. I was hoping the FM tuner on the MX110Z would pick up the local NPR station but it's too weak of a signal. Any sort of antennae attachment I can do?


In general though, I hooked everything up and the sound is truly lovely. I'm connected to the 8 ohm output. Any reason I can't use the 16? Also curious as to how I should be adjusting gain (versus master volume on the MX110) on the MC30s and the MX110?

Looking forward to continuing to learn more from everyone on here and continuing to read through the extensive discussions!

Thanks so much in advance as well for the recommendations!

Best,
Albert
 
Albert, welcome to the club. I too recently joined this wonderful world of Mac gear. I have a MX110Z running the mc30s and everything everyone has said about them being one of the sweetest combos you could own has come to fruition. I unfortunately have not had the same experiences with you and am a novice to the technical side of this so I cannot help you with your problems here. However, I run my digital files through a DAC from my Macbook, and I can tell you the difference in sound between the airplay and a direct usb connection is night and day. At least for me it was....try it you may be as blown away as I was, I believe this to be the best connection in terms of purity. Great looking set up and again, congrats!
Patrick
here's mine:
 

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Thanks Patrick and awesome setup as well :)

How high is the gain set on your MC30s as well as the aux output knobs on the top part of your MX110 (the part behind the faceplate that is hidden when the unit is pushed into the wood cabinet)?
 
Good evening everyone!

Been reading a bunch of threads on Audiokarma for quite some time and the breadth and wealth of knowledge on here continues to amaze me.

In no small part based on the reading here, over the last two months I've slowly assembled my audio setup:

20140731_215137_zps47837143.jpg
[/URL][/IMG]

A pair of MC30s powered by a MX110Z with everything running to a pair of Kauri wood rebuilt Klipsch Heresy's w/updated crossovers, Crites woofers and K77M tweeters.

The MC30s were restored prior to my purchasing and look great cosmetically. Per the original seller, both have new filter caps, new bias rectifier and bias cap. Both had 820k bias resistors replaced that had change value to 950k. Both check on MC load resistor at 38 watts output at <.5% distortion and 1 watt .05%. All measurements made with HP 339A Distortion Analyzer.

The MX110Z was also restored and all tubed checked with the bad ones replaced.

hard to see in the quick photo (table is pending so everything is currently on the floor haha) but I've got a Schiit DAC linked to an Apple Airport Express to pipe in my digital audio as well. Technics MK5 (I used to be a DJ) for my vinyl needs to be connected as well.

So for the questions for the pros:

1. When I power the amps up, there is a light crackle/hiss in both speakers and one speaker picks up a spanish radio station. After some shuffling/trading of wires, amps etc. It seems like the radio station signal is coming from one of the MC30s. What could be the etiology? Something to dig into?

2. If I'm playing the music even at reasonably low volume (background music) the hiss/crackling can't be heard though... is this normal or should it be completely silent?

3. Based on the MC30 restoration details from the original seller, is there anything else I should be checking out/changing? I can do some simple soldering if there is anything else critical that needs changing.

4. I was hoping the FM tuner on the MX110Z would pick up the local NPR station but it's too weak of a signal. Any sort of antennae attachment I can do?


In general though, I hooked everything up and the sound is truly lovely. I'm connected to the 8 ohm output. Any reason I can't use the 16? Also curious as to how I should be adjusting gain (versus master volume on the MX110) on the MC30s and the MX110?

Looking forward to continuing to learn more from everyone on here and continuing to read through the extensive discussions!

Thanks so much in advance as well for the recommendations!

Best,
Albert

Very nice setup you have there. :thmbsp:

As for the crackling when powering up and the Spanish radio station in on speaker - sounds like an issue with the MX 110 - it may need additional service and/or tube replacement.

Try swapping the L & R channels on the preamplifier outputs and see if the radio station is then heard at the other speaker. If so, then that issue almost definitely lies in the MX 110.

Next, try powering on the amplifiers without being connected to the MX 110 and see if the crackling continues. (Disconnect the RCAs from the MC 30s) If it disappears, that problem is either in the preamplifier or possibly you have faulty connection.

If the crackling persists, you might have something as simple as bad tube pin contacts in the amplifiers. Gently move the output tubes - GENTLY - while powered on and see if the movement affects the crackle.

I had the crackle problem in my 240 when powering on and off and poor pin contacts was the issue. We used a awl pick to gently bend the socket contacts and this cured the problem.

Output taps. You should always match the output taps to the speaker impedance for the best combo of voltage and load for maximum power with the lowest stress on the amplifiers. If the speakers are rated 8 ohm - use the 8 ohm taps.

Antenna. Depending on the strength of the FM signal as seen by the tuner in your locale, you may well need a better antenna. A rooftop outdoor antenna will generally provide excellent reception; an outdoor directional antenna used with a rotator for the very best reception. It all depends on how far you're willing to go.

Hope some of this is helpful and welcome to AK. :wave:
 
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Wonderful help and thank you so much for taking the time to write it all out!

I've narrowed it down to 1 MC30 after doing all the various switcheroos of cables, outputs etc. The FM interference is gone now actually as of yesterday with no changes from me on anything. The faintest static sound can be heard if you're about 8" away from the speakers with no audio playing but the system turned on. Otherwise it is clear as clear can be.

I'm going to pick up some deoxit and use it on each tube connector plug to ensure a clean connection in that regard. Wiggling the tubes didn't seem to affect much of anything in terms of static/noise output... but just in case :)

Thanks so much again and really excited to be learning more on here!
 
Oh - Gain controls. I adjust by ear to get to minimize hiss while still being able to get decent volume levels without having to set the volume control too high - which also results in hiss.

It's a bit if a balancing act but you'll soon find what works best with some experimentation.
 
Wonderful help and thank you so much for taking the time to write it all out!

I've narrowed it down to 1 MC30 after doing all the various switcheroos of cables, outputs etc. The FM interference is gone now actually as of yesterday with no changes from me on anything. The faintest static sound can be heard if you're about 8" away from the speakers with no audio playing but the system turned on. Otherwise it is clear as clear can be.

I'm going to pick up some deoxit and use it on each tube connector plug to ensure a clean connection in that regard. Wiggling the tubes didn't seem to affect much of anything in terms of static/noise output... but just in case :)

Thanks so much again and really excited to be learning more on here!


You're probably getting a bit of crosstalk from the tuner.

You're not hearing the radio station when the amp is disconnected from the preamplifier, are you...?
 
^ I was (I think... need to pay attention more next time I hear it) if I recall. My tuner was set on a talk radio station though and the radio station I was picking up via the MC30 & speaker was a spanish one.

Thank you for the recs on gain adjustment! Its quite interesting playing with all the various controls and reading over the MX110 user manual as well. Crazy how advanced the system and features were for something that vintage!
 
That Spanish radio thing at one speaker is quite a mystery. :scratch2:

Keep an eye on it is all you can do I suppose...

Next time it occurs, turn the mode selector to "REVERSE" and see what happens.
 
update... so no more radio station at all. Haven't done the Deoxit to the tube sockets yet.

For a brief 5-10 second span of time when I power the system on from a cold start I get intermittent static from one speaker and then it goes away for a while. Then as the music keeps playing I'll get the crackle/static near continuously but it almost goes away completely after 1 hr. I'm pretty sure it is one of the tubes because this effect changes from one side to the other when I swap out the MC30 tubes from one to the other. Time to check the tubes to see if one needs to be replaced?

Also was curious as to how I can access the pots on the top side of the MX110 to clean it with the spray? One of the channel gain pots is SUPER crackly when i turn it.
 
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Chinorlz,
Sorry, been away for a bit. Thanks I absolutely love this set up man, andits great to hear you are on your way to getting er dialed in. I can use a lot of schooling from the more seasoned vets here, but for my system it sounds best with the mc30s at full go, and my main on the receiver both at about 1 o'clock which I assume would be 60 percent or so. Just swapped it out last night with the mc275.... Also a nice combo, a bit more accurate I'd say. Aa and of course a picture of said setup :music:
 

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update... so no more radio station at all. Haven't done the Deoxit to the tube sockets yet.

I'm pretty sure it is one of the tubes because this effect changes from one side to the other when I swap out the MC30 tubes from one to the other. Time to check the tubes to see if one needs to be replaced?

Also was curious as to how I can access the pots on the top side of the MX110 to clean it with the spray? One of the channel gain pots is SUPER crackly when i turn it.

Congratulations

On the Radio Station, the electrical conduits behind your system look exactly like a dipole antenna, you may be getting induced signals in your system from the antenna. If the radio returns, move the system away from the conduit and see what happens. You could also check the conduit grounding in the room and the house. If needed consult Gregory, probably the most antenna knowledgeable person on this forum. It's been a while since I would occasionally hear the police through my LaScalas, perhaps because they went digital, now encrypted??

Testing all of the tubes sounds like a good idea, do the replacements need to be a matched set, and will the bias have to be adjusted????

When you open the system to clean it, remember that the power which may still be present in the capacitors is sufficient to kill you. You could also find your local guitar amp repair shop that is very comfortable with tubes and have them check your systems and clean the contacts and switches.

With the service manual, I'm pretty sure the local guitar shop could do the work for you. If you want new matched tubes and the capacitors replaced they may agree to let you bring the parts in with the amps, in and out in a couple of days. They may also have the caps on hand given the tech and the era, I would ask.
 
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