McIntosh MC275 CLS and Krell

[mosttoysrk]

After reading all the praise for the McIntosh MC275 I have put it into my CLS (1st version with new panels) system replacing my Krell KSA-250 and using the Krell KBL as my preamp.
The McIntosh I purchased is the series IV and I am running MIT cables now but with a poor setup to the speaker terminals. I am waiting for converters from Hong Kong to use my spades so I have zip wire connecting to the spades.
I am underwhelmed.... is it the KBL or just the crappy setup for the speaker wires. I am running it in balanced mode.
The amp is in mint shape with only about 40-50 hours on it with the stock tubes.
The sound compared to my Krell KSA is thin, and a little coarse. I was expecting if anything it to be a little on the bloated heavy side.
I have it connected to the 4 ohm terminals.
Is it my Krell KBL? It is not a small difference between the Krell and the McIntosh. The system now seems underpowered.
On small jazz recordings the sound is better but to be honest I haven't had a chance to really listen just a 40 minute session.
Hints? I know Neil has great results with this setup but he is using a Levinson preamp. I was also surprised at how cool it runs for tubes, the Krell KSA runs much hotter. The transformers on the Mac barely warm.

 

[nsgarch]

Rich, my MC275 actually took overnight and the whole next day to 'burn-in', plus the person I bought it from said he'd already used it for a couple of days. Not just the tubes, but other parts like transformers and especially capacitors need some use before they sound right. Here's what I think, after the amp has had a total of about 70-100 hours burn-in:

1. Make sure the stereo/mono switch is on stereo (sounds stupid, but we've all been there ;--)

2. I don't think your nasty-but-temporary speaker connections are that big a factor. But I do hope the MIT speaker cable you're using doesn't have a network box and isn't longer than about 8 ft. I can explain why if you like, but read this first: http://www.sanderssoundsystems.com/Cable%20White%20Paper.htm

As I said, my amp settled in a bit sooner due to some previous use, but it still required a good 30 hours. However, what truly and unexpectedly blew me away (because I was already happier than with my Levinson 23.5 -- not an easy act to follow ;--) was when a friend brought over a couple of ratty old Telefunken 12AX7's he'd yanked out of a vintage Fisher receiver. Installed in the gain/driver positions of my 275 (V-2 and V-5) the difference was really night and day! I have a couple you could try if you like. --Neil

 

[mosttoysrk]

Update: I ripped the zip wire out and found an electronics parts store that carried old terminal speaker connectors like I am waiting for to come from Hong Kong but with a hole in the center to place one half of the spade in and it tightens down with a screw.
Reconnected all connections turned on the Mac and let it run for 30 minutes and then sat down for 2 hours......
OK .... I see what the excitement is about. It is a very very listenable smooth sound. Not as detailed or dynamic as the Krell setup but after long listening more real.
The Krell setup is an imposing detailed sound with much more bass coming from the panels than with the Mac. The Mac is about finesse. After listening to the Mac I can see how some would find the Krell "dark" which before the Mac I could never understand.
Am I weird to want to keep both amps though for different music? The Krell is great for classic rock where the Mac is amazing for Jazz and vocals.
How can I get this by my wife....
Thanks Neil for all the help in getting me to believe in the Mac. I am tempted to try out a tube preamp in place of the Krell and see what happens... any advice?

 

[tonepub]

While the 275 is not the greatest match for the current ML-s, it is quite nice with the CLS.

As you get really used to the sound, experiment with some NOS tubes to replace the input tubes. There are a few different ways you can go sound-wise and chances are good that an excellent set of NOS tubes will significantly outlast the stock tubes as well.

If you are feeling pretty wacky with the checkbook, go for a great NOS set of output tubes like Neil did. That's the last step on the 275 and will take it to another level.

It's a great combination....

 

[GregLett]

While the 275 is not the greatest match for the current ML-s, it is quite nice with the CLS.

As you get really used to the sound, experiment with some NOS tubes to replace the input tubes. There are a few different ways you can go sound-wise and chances are good that an excellent set of NOS tubes will significantly outlast the stock tubes as well.

If you are feeling pretty wacky with the checkbook, go for a great NOS set of output tubes like Neil did. That's the last step on the 275 and will take it to another level.

It's a great combination....

Tonepub,

Are you a tube guy? can yu point me in the direction of some good pre amp tubes.

I understand mosttoysrk what you are saying about the Krell. But I found out that the pre amp made all the difference in my setup. I have the slam and still have the finesse. This was made possible with a Cary pre that i have on loan this week. I want to try different tubes in my pre first before I unload it for a Cary or ARC.

 

[tonepub]

My two favorite guys are Andy at Vintage Tube Service and Kevin Deal at Upscale Audio.

Give them a call, tell them what you have and what kind of sound you would like...

Either will be able to give you some good advice.

 

[GregLett]

My two favorite guys are Andy at Vintage Tube Service and Kevin Deal at Upscale Audio.

Give them a call, tell them what you have and what kind of sound you would like...

Either will be able to give you some good advice.

Thanks tonepub. I actual have the pre Kevin sells.

 

[nsgarch]

OK, we all know what you don't like,

While the 275 is not the greatest match for the current ML-s, it is quite nice with the CLS....

and even though you seem to be a lone voice, you never to miss an opportunity to remind us. Now, you've suddenly decided that the MC275 is OK with the CLS but not any of the "current" ML-s? There's simply no electronic or acoustic reason why that should be so. My direct experience with Vantage/Summit/CLS owners driving their speakers with Mac MC275, MC2102, and MA2275 is now running 6 to 1 in favor (you being the 1) So I'm citing a consensus, and you're offering one (so far) personal opinion; I just wish you wouldn't make these pronouncements above the banner of your audio publication, perhaps leading a new, or less sophisticated audiophile to unwittingly accept them as fact, and/or you as an authority. Aren't you worried it could all come back to bite you?

For anyone interested in some actual science as to why SS amps are a little handicapped compared to tube amps when driving an electrostatic (capacitative) load (i.e, they need more power for the same performance) I have tried to capsulize the high points here: http://www.martinloganowners.com/~tdacquis/forum/showpost.php?p=58808&postcount=22
I'm not discounting SS amps with stats for those who prefer that sound, for HT, or for those who don't want to bi-amp an older ML hybrid speaker. Gayle Sanders himself is/was a Krell fan for many years.

I've also addressed some common misconceptions many people pick up through hearsay, or just by trusting bad information http://www.martinloganowners.com/~tdacquis/forum/showpost.php?p=58928&postcount=27

 

[C.A.P]

Todays Martin Logans are far different to drive than the Logans of the old. Tube amps are good when paired right . That being said , for me , the Krell gives a footprint to the Quests I have like no other. (I like the newer designs but I wish they made them un powered so we could run our own amps for the bass) Imagine a Prodigy totally BI ampable. It would be cheaper to make and sound better when paired right. The newer speakers do not need all that currant, as they are self powered.(probably with a Class D amp. ) Not that it is a bad thing but I guarantee they would sound better with a good quality amp driving the low end.

 

[twich54]

There's simply no electronic or acoustic reason why that should be so. My direct experience with Vantage/Summit/CLS owners driving their speakers with Mac MC275, MC2102, and MA2275 is now running 6 to 1 in favor (you being the 1)

Neil, I enjoyed reading your links to your previous threads and thank you for the very good explanation as to the 'driving characteristics' of our Logan Speakers. I think a clear point you have made, and I agree, is that the panels on our speakers are more amplifier dependent than we realize. Or as Roberto likes to say.........
"Quality Watts" will yield what our Logan's have to offer.

 

[nsgarch]

Quality Watts

Neil, I enjoyed reading your links to your previous threads and thank you for the very good explanation as to the 'driving characteristics' of our Logan Speakers. I think a clear point you have made, and I agree, is that the panels on our speakers are more amplifier dependent than we realize. Or as Roberto likes to say........."Quality Watts" will yield what our Logan's have to offer.

I agree with Roberto, and have understood for a long time that watts can have different capabilities, depending on how they are produced.
Recently, I was surprised to learn that electrostats are also more dependent on speaker cable design than I 'd realized. I just assumed that a cable I liked with dynamic drivers, I would also like with stats -- a deeply flawed assumption!
Although most conventionally designed, quality cable will work very well, a little extra inquiry and research during the selection process will help identify a truly worthy short list.

 

[Bernard]

.................
Recently, I was surprised to learn that electrostats are also more dependent on speaker cable design than I 'd realized. I just assumed that a cable I liked with dynamic drivers, I would also like with stats -- a deeply flawed assumption!
Although most conventionally designed, quality cable will work very well, a little extra inquiry and research during the selection process will help identify a truly worthy short list.

Neil, if you ever try the cable made by Roger Sanders, please post your findings here. I wonder if the guys at ML have tried it.

 

[tonepub]

Neil:

Watts are watts. There is no difference between tube watts and transistor watts. It's simple math and physics.

The reason the 275 works much better with the CLS than the Summits is because the CLS does not dip as far down on the impedance scale. The ClS only goes down to about 2.5 ohms which is a lot easier to drive than the .7 ohms of the Summit. I took my 275 over to a buddies house with the CLS, because I obviously no longer have mine for a direct comparison...

Where the 275 rolls off the highs on my Summits, it does not do so on the CLS, so I'm not making any of it up. When my friend came over here, we did the same thing and he drew the same conclusion. The CLS is a completely different speaker to drive than the Summit or Vantage. The folks at ML will back me up on this one...

So far the only really outstanding Tube amps I've heard matched with the Summits have been the ARC ref, the Manley 250 monos and the CJ 140 monos. All the small tube amps I've tried thus far have had the same problem as my 275....

By the way, have you ever hooked a 275 up to Summits?

 

[edwinr]

I am perplexed. How could changing speaker cables have wrought such a difference? I know in some very good systems upgrading cables can help to fine-tune or tweak a system. But wresting such a dramatic change is puzzling. Maybe changing the speaker cables coincided with the amplifier having completed a settling in period - or something...

P.S. Re the tube vs s/s thing. I love tube gear. My Pre amp is an ARC LS25mkII. I didn't go tube power because for the kind of driving power I like, inexpensive tubes just don't do it for me. For the same price as a pretty ordinary tube power amp, I bought an outstanding s/s power amp. To me, watts are watts. Whether tube or other wise. And some less expensive tube power amps IMHO just don't have the bandwidth of a good s/s. Although one option that crossed my mind were TWO MC275's for my Summits... But I just didn't like the sound with the Summits. I've heard the MC275 with other speakers - and it sounds great. I guess like anything, you just gotta suck and see if it's right for you. Ramble over... :clap:

 

[nsgarch]

Neil:Watts are watts. There is no difference between tube watts and transistor watts.

Oh yes there is! It's all here: http://www.allaboutcircuits.com/vol_2/chpt_11/4.html but you might want to read through the basics first.

It's simple math and physics.

Your notion that math and physics are simple, proves you understand neither . . . . .

The reason the 275 works much better with the CLS than the Summits is because the CLS does not dip as far down on the impedance scale. The CLS only goes down to about 2.5 ohms which is a lot easier to drive than the .7 ohms of the Summit.

Geez! Where do you get this half-baked information? The CLS II, IIa electronics module dips to .6 ohm @ 18KHz. The newer CLS IIz electronics module dips to 1 ohm @ 20KHz (1.5 ohm @ 18KHz) ---- from the CLS II Owner's Manual and the IIa and IIz upgrade memo to owners of record, 2/12/92.

Where the 275 rolls off the highs on my Summits, it does not do so on the CLS, so I'm not making any of it up.

I'm sure you're not making it up. But you are drawing the wrong conclusion as to the reasons for the lousy sound. It isn't the amp, sorry. If that's what you're hearing, I bet you're using a multi-multi-stranded cable (aren't you a Cardas fan?) and just one MC275 in stereo.

The CLS is a completely different speaker to drive than the Summit or Vantage. The folks at ML will back me up on this one...

Hell, I'll back you up on that one! So what!? The 275 works very well with them all. But if you want to be fair in your comparison to those other amps, you would have to use two MC275's in mono mode when driving the Summits. That's how I heard them (with Transparent speaker cable) and they were marvelous -- no roll-off! Further, the Summit and Vantage are actually easier to drive than any of the CLS's because they cross over at 270Hz and 400Hz respectively, while the CLS goes flat all the way down to 80Hz, and then slopes to zero @ 35Hz.

 

[nsgarch]

Although one option that crossed my mind were TWO MC275's for my Summits...

It distresses me that you didn't follow your intuition and at least audition a pair. It also distresses me that McIntosh continues to handicap their new amps and preamps by furnishing them with those terrible OEM Chinese signal tubes. Oh well . . . . .

 

[edwinr]

It distresses me that you didn't follow your intuition and at least audition a pair. It also distresses me that McIntosh continues to handicap their new amps and preamps by furnishing them with those terrible OEM Chinese signal tubes. Oh well . . . . .

LOL! I did!!!

But to be perfectly frank with you, I just didn't connect with the sound. I kept going back to quality s/s power amps, and after auditioning the Mark Levinson (No. 432) and others in my home, I choose the Pass Labs X150.5. I was looking for a clean clear and very wide bandwidth uncolored sound to match the rather lean presentation of my Audio Research. What I can say about the Pass Labs, is the AMAZING ability to reproduce the VERY low bass frequencies the Summits are capable of. In fact the Pass Labs are more capable in the low end than the No. 432! I have to say that NO tube power amp that I have heard, that doesn't cost as much as a small quality car, can do this. Of course this may not matter to many people who listen to different music, or have difficult rooms.

P.S. I respect your passion about your system and your MC275's! I love arguing the relative merits of our respective hi-fi systems.

 

[TomDac]

Let's play nice, guys.

 

[taylode]

Let's play nice, guys.

Perhaps someone could explain to me how an amp could improve the base response in Summits. I would think with it's onboard amp that your systems amp would not have much, if any, affect on base response.

 

[edwinr]

Let's play nice, guys.

Awww, Tom. You spoilsport, you... :angel: