McIntosh MC-30's, MX110 tube discussion. Perfect 6U8, 12AX7, tube? See post #43 for Steve's input.

Finally getting signed up and posting here......and giving the good folks of this forum a note of thanks regarding the McIntosh MC-30's.

First of all, there's LOTS of familiar screennames here. We get around, don't we?

System: AH! Njoe Tjoeb 4000 CD > McIntosh MX-110 > McIntosh MC-30's > Belle Klipsch. It is where the best of my analog sound "wants" and digital convenience seem to meet, at least for an average joe like me! I LOVE tube CD players, too - at least through the horns.

Now to the 30's: This forum is a great deal responsible for my ownership and current satisfaction with the McIntosh MC-30's. Steve sure has it right when he tells us these are the MIDRANGE KINGS for bringing those old recordings back to life! And with some tube rolling as recommended by Steve, they begin kicking some serious booty on just 'bout everything else, too! The MX-110 really mates well, as the solid state rectifier in the MX-110 seems to give just enough tightness/firmness to the bass to maintain my rock and roll tastes - with the sweetness to pull off just about everything else. Vocals, guitar, live rock and roll, acoustic instruments - just about everything sounds gouda through my 30's


I followed the small tube recommendations given from Steve, for the most part, having Telefunken 12AX7's in that key first slot, RCA 12BH7's, Amperex 12AX7 in the last 12AX7 (which is a slight departure). But as Steve told us - the key small tube is the 12AU7. I tried RCA cleartops (not bad, but a bit "clinical"), the Mullard (still OK, but a bit too smooth/rolled off/less "open"), and then finally, the Amperex/Holland made 12AU7. The Amperex was JUST the ticket for these......which I must say was a bit of a surprise, as the Amperex was touted as not being as desireable on "bright" speakers.....but they sound wonderful on my Belle Klipsch. Yes, they are brighter, but yet they have liquidity/smoothness, too. Just more open and musical - the "intangible" things that's hard to measure. These tubes made this amplifier QUICK - BIG upgrade in the pace, rhythm, and timing department vs the all greyplate RCA lineup I used for the small tubes in the first year of ownership.

I'm currently mulling over the output tubes now....it seems that Steve really likes the GE 6L6's. I was most pleased when I read that these were "cheap" - but that was a while back - and they are getting pricey too! Hopefully when I get more dough to try the GE's, I will - but geez-O-pete is it expensive sampling tubes in these babies - but they sure do reward me when I get the right ones I'm using the RCA blackplate 6L6GC now, as they are all that I have. My budget dictates that I do this in stages - small tubes first, then I'll get to the outputs - hopefully soon!

Anyhoo, I just wanted to say THANKS!!!!!

 

Someone I know has some Westinghouse 6L6GC's...

Welcome aboard!

 

I'm interested in your experience with pairing the MX-110 with MC-30s. A vintage pre is my next purchase - right now I'm not using a preamp at all with my MC-30s. Anyone else with thoughts to add please lend a hand...

I found an old thread with an interesting comment by Steve Hoffman;

In a thread from March 2004, Steve Hoffman wrote;

>I think there are like five different versions of the MX-110.
>Some I've heard stink, others sound wonderful... Try and listen before you buy...

(the March 2004 thread title is "Need Preamp Advice for a Marantz 8B")

 

Forgive my ignorance, but what "tube slots" are what on this amp? I assumed you'd want matched tubes in a tube amp. I suppose each stage/slot does something different, so using different tubes would make sense. This is probably tube amp 101, but a short explanation would help me out here...

 

Oh, I just had a brain fart, that's all. I understand... the output tubes are matched. So you can vary the preamp tubes to change the sound, right? It's a matter of understanding the circuit and what each tube is actually doing, right?

Sorry for getting OT here...

 

Thanks Steve. Actually, I DO want to get technical! I won't derail this thread any further... instead I'll Google some info on tube circuits and go from there.

 

So Steve, just curious regarding your opinions on the output tubes......you seem to really be a GE fan....I was really interested in those per your prior comments. I was surprised you didn't tell me to get the GE's too!

I do intend to try the Tele in the last slot, but as all I had here was ONE tested pair of Teles, that one pair went in that leftmost slot. The other pair I have hasn't been tested, although the seller said they were strong, but I always verify before install. The last slot, at least amongst the other tubes I've tried there, didn't seem to make nearly the sonic difference - I would call this tube "mild sonic seasoning". The Amperex came out the best of what I had that was tested/verified first (RCA greyplate, Mullard, Tesla, Amperex). If it has nearly the effect that the first Tele did (which was a KNOCKOUT - no other tube came close), I'm really in for a treat!

I've got to get a tube tester of my own!!


On the MX-110: I had two different units of the "Z" series MX-110's - which was the last version they made. The first unit was stock - and it was "OK". But the second unit.....which was almost perfect and just the unit I wanted for internal audio restoration is DA BOMB. This unit has had the internal caps in the audio path replaced with fresh and as similar caps as are available to bring back the life in the unit. IT SOUNDS GREAT. It fits the 30's very well, and the 30's fit the Klipsch just perfectly. 30 "tube McIntosh watts +" is a lot of "testicles" on a pair of Belle Klipsch - but because of the sweetness of the combo it gives near SET sweetness plus good power all in one. I seriously believe and hope that I will never have to buy new amplifiers. I like 'em so much, I am eventually going to buy a cosmetically challenged pair for future parts, so I am more assured of MC-30's for LIFE. I've chased this sound for 20 years. I feel like Chief Brody in Jaws:

"Hey, I got it!"


The "rub" with rebuilding internals on old Macs is that this hurts resale value - but is most necessary on this old gear for long term use. Trust me, many of these parts degrade over time. Having a Mac tech who knows what to change, and with what parts (as to not lose the sweet sonic qualities) is also key, because if you go changing caps that are not a good match for the McIntosh units, the sound will become something that is NOT McIntosh. Not to mention safety and transformer life.......

It is for the reasons stated above that the MX-110 reviews are all over the map - even amongst individuals who have heard several with mixed results - because the internals will mak a difference in what you are hearing.

 

Hmmmm.....interesting what you say, Steve, about the midrange "magic" in the RCA being in the lower treble. A key area in the Belle Klipsch is the lower MIDRANGE as it comes through the bass horn. Given my current satisfaction with the midrange currently (the Teles in the 30's were KEY here), maybe the GE's won't be "all that" in my system - but maybe they will. I guess I'll have to try them and see.

Regarding the bass of the 110: I have compared my 110 against some pretty stiff and expensive competition. The one area that the "cost is no object" preamps do better than the 110 is in the bass area. One thing I find key is to make sure you have Telefunkens in the 12AX7's in this unit too, as they seem to have a special synergy with the McIntosh gear - and the 110 is no exception. Another point is the 6U8's in the linestage....rolling this tube will improve the "thunkiness" in the bass that the 110 can sometimes show (using Seimens currently - but still experimenting some). The tube rolls in the 30's helped in this area, too.

It is a bit of a tradeoff with the SS rectification in the MX-110, but the point is minor. Especially with some tube rolling, the bass performance can be improved some. My CD player helps, too (I can tube roll there as well). And for what the MX-110 sells for, it's really a minor point. Improving upon the overall performance of my current MX-110 will cost mucho bucks. I'm pretty pleased overall.

The C22 will address the issue, but will cost over $2000 - and no tuner included.

I edited the post to clarify the MIDRANGE issue on the 6L6's and Belles - I guess I need to read more carefully

 

"The Tele 6U8 sounded dreadful; thick and sluggish..."

I agree, Steve....the 12AX7 may be "all that", but the 6U8's not so good. I'll be on the lookout for some old RCA's - they've been on my short list, but the right vintages are harder to find - and the later ones with boxes labeled "6DK8" are horrible in terms of reliability....my tech went through 10 of these later versions NOS, and got 2 suitable for linestage use.....and those lasted two weeks.

The Siemens do a pretty good job overall....."balanced" is the word I would use here. A bit more "musicality" might be in order, though.....and I've read that the older RCA's are good in that department. I'll be on the lookout for these.

Thanks for the responses, and thanks for a very cool site, Steve!!!! How addicting.......

 

Sure, Steve! I fixed the location, and I'll fill in the rest soon. It's dinnertime

 

I'll simply provide an addendum to the expertise Steve has shared in this thread.

Here's a tube complement for an MC-30 (I don't believe the design ever changed [?]);

Preamp: 12AX7
Phase Inverter: 12AU7
Voltage Amp: 12BH7
Driver: 12AX7
Rectifier: 5U4-GA
Output: 1614 (or 6L6GC) x2

Relating to Steve's MC-30 photo in post #6, the above listing matches the order of the tubes as seen in the front row from left to right. The two output tubes are the large ones in back (with orange paint), between the black transformers. I believe (hope) I have this right - any corrections or additions are welcome.

I've learned a lot from this thread. It's going to help me to tune my MC-30s to optimum shape. Thanks...

 

Ok, I took Steve's advice, and after having that last pair of Tele 12AX7's tested, rolled them into the last slot.

I'll quote Steve from another older thread re the 30's:

"Spooky, lifelike 3-D realism"

Oh Yeah! There was no mistaking the results of that final roll.....if you want to believe that the singer is in the room with you, all Tele 12AX7's in your 30's is recommended. The Bugle Boy tubes are good, but in these amps the Telefunken 12AX7 is THE tube - in both slots. That midrange just FLOATS out there......I plopped in Steely Dan's "Aja" and was sold by "Deacon Blues"

And on old recordings (Like Paul McCartney's "Uncle Albert/Admiral Halsey"), for the "bring singer's voice to life" test - it sounds like they got remastered. I have NEVER heard that tune like that before.






Not quite as firm in the bass - but my bass in this system was "thunky" or "bloated" at times. No more. Steve's "dream" lineup for tubes is very hard to argue with - this is the best I've ever heard these.

 

Hi,

What pre's have you compared the 110 against and what were your impressions? Have you compared it w/ the C-22 and, if so, what were your impressions?

Take care,
Jeffrey

 

Jeffrey -

Most notably, I have compared the MX-110 to the Supratek Syrah and C22 - in identical systems (just swapping the MX-110 with these).

The major difference is twofold - and are both related to the same issue: Bass. The bass in the MX-110 can be a slight bit "hard", "thick", or "thunky" on occasion (I presume this is from the SS rectification - but that's only a presumption). Tube rolling is a tremendous help, especially in my 30's, (system synergy, maybe). But the higher class preamps offer a more natural and unforced presentation - a more "liquid" bass - without a hint of bloat or thickness. That lack of bloat translates into an overall presentation that is more relaxed, believeable, and transparent.

What is interesting to note, however, is the overall performance of the MX-110 against these "super" preamps. When one considers that these better units are 3-4 times the price, the MX-110 is like getting a 15 million dollar MVP quarterback for 4 million dollars. The MX-110 performed admirably and comparably in other areas to the higher class preamps - the presentation overall was very good - good transparency and musicality. The midrange is EXCELLENT in the 110, with good treble as well (hard to make right for us Klipsch owners). Bottom line: I left the comparisons/head to head demos feeling VERY GOOD about my MX-110 - and understanding that my situation here was akin to many in audio: Often, if you look around, you can obtain 90+% of the performance for 1/3 the price. Definitely the case with the MX-110 - it is an excellent choice if you have a "salary cap" - and especially if you mate it with McIntosh tube amps. I have also hooked this into systems with big $$$ SET and other P/P amps too (Ron Welbourne Moondogs and JFL Horus, amongst others)- and with similar good results.

If I can plug this thing into these kind of high class systems using high efficiency (read: ruthlessly revealing) speakers without too much offense/critique from those system owners, I must be in the ballpark. I have left several demos with my 110 with quite a smile on my face, for it is easy to want "the better one" just because you think it is better. And it may be better - but when comparisons such as these are made, I realize that for MY budget, it isn't $3000 better, LOL.....and for even an unlimited budget, the MX-110 comes DAMN CLOSE.....closer than it should for the $$$ invested.

And when you look at the tuner, the MX-110 is a steal - even at $1000+ prices that good versions currently go for. Still worth every penny.

 

Nectar,
You sure are making us MX-110 owners smile out here. Most of us have not had the opportunities to do the extensive comparisons and tube rolling that you have already done, so your posts are very informative for us. The bass is indeed the one area in which I would like improvement with my system. But to be clear about the MX-110, I find the bass to be extremely accurate, warm, and agile. Subtleties are in abundance. Its just that deeper slam that seems to be missing. It is definitely a worthwhile tradeoff for most of us, but I can't help but wish there was some way to get that extra little bit out of the MX-110 bass.

 

Hi Ian,

I believe you can accomplish your goal w/ tube rolling BUT it'll be at the expense of the mid's.

Take care,
Jeffrey

 

Ian, I have always had the opposite problem - too much bass in the system. One of my goals was to "naturalize" the bass by bringing out more smooth highs in the system, and to tighten the bass without bloat.

I have also found and learned a great deal over the past few years what bass should really sound like in a system. Very often, "good bass" is mistaken for over-accentuated bass in systems, and I was no exception: I was raised on solid state amplification in front of numerous rock stages and concerts. So yes, I demand good bass. But "good bass" means accurate, and not overaccentuated - often misunderstood my many who attempt to have "good bass" in their systems (just hear all the vibrating car trunks, eh?).

In my case, much of the solution was not in the MX-110 - it was in my McIntosh 30's. Of course, my MX-110 has had the audio path recapped (so it is much cleaner - and not representative of an all original unit), as well as some components in my 30's (filter capacitor, mainly - and this tightened the bass in the 30's considerably). The tube rolls in the 30's played a significant role in making the bass issues in the system better overall (hint: Telefunken 12AX7's), and is MUCH more natural sounding. At times, I have to tell myself that there is a difference in bloated or overemphasized bass (which I am all too used to, having listened to and owned many cheaper, lesser quality systems over the years). In my current system, I am reminded that this system will sound more "bass lite" than on some selections versus others, when there never seemed to be such a marked difference before. that is from the RECORDING, and the system being true to that recording.

When I used the MC250 (older version of the 2105), it wasn't nearly as good in the bass. It had good bass, but the 30's were better in the TRANSPARENCY department - albeit not perfect. More "slam" in the solid state version, but more accurate and natural on the 30's. It is a good combination of power and sweetness that is pretty easy to live with - and the self critique is really more "hair splitting" than anything else.

I also have another advantage: When I want deep solid state slam, I have my theater. When I want a more musical presentation (sweeter mids, etc.) I go to the Mac tube system. Similar speakers, MUCH different results/presentation.

Some tube rolling on the linestage 6U8's on your 110 might be worthwhile. What are you using now?