Nothing safer. :thumbsup:

The 1800W max capability of the CR7 outlets is ample for this purpose.
Alfmonster: thanks for the previous "thanks", but I did not write the post you quoted. I would think TSmith8605 appreciates your comments.
I think you have gotten several answers on your questions from others.
If you look at Roger Russels specs on the preamps, you will see the back panel information for each one stating what connections are there. If it says:" speaker control relay switch" then you can hook up the SCR. The C26 and 27 are missing this information.
The SCR-2 has 2 wires attached to it, one a very heavy gauge power cord and the other a thin control wire with a special 4 prong plug that plugs into the back of the preamp.. There are 2 power outlets on the SCR-2 box.
But as has been mentioned, it appears the C27 has lots of power switching capacity.
The 2100 consumes 450 watts for rated power and the 2105 needs 430 watts for rated power. If the C27 can switch 1800 watts and has a separate power switch, I would feel safe with that. I would not be doing this with my C28's without the SCR-2.

Oh gosh, thank for the heads up I made the edit to @ the correct person. I'm not sure why I made the mistake - but thank you for this as well. Its really helpful to know the max wattage the c27 can handle as I too thought the CR7 was a C27 typo. @62caddy, Just looked up the CR7 to see what you meant
AudioClassics has one on sale. If my system builds out to something larger I may look to get one. Thank you!
 
Oh gosh, thank for the heads up I made the edit to @ the correct person. I'm not sure why I made the mistake - but thank you for this as well. Its really helpful to know the max wattage the c27 can handle as I too thought the CR7 was a C27 typo. @62caddy, Just looked up the CR7 to see what you meant
AudioClassics has one on sale. If my system builds out to something larger I may look to get one. Thank you!

I have a CR7 in each of my systems - essentially a very basic C31 preamplifier. Very handy little unit. They seem to be commanding significantly higher prices today than when I had gotten mine.
 
I also have a CR7 for each of my systems and I owe it to you Caddy!!:D Seriously though, before I became a member here, I read several of your posts regarding the CR7 when researching them and pulled the trigger. Couldn’t be happier with them. And speaking of them commanding more $$, let’s say I’m extremely happy I pulled the trigger when I did.

I have a CR8 that is just sitting there in a box as it came with one of the CR7 purchases. Not sure what to do with that.
 
C-28 combined with. a 2100 gives a nice euphonic sound. Issues with the C-28 made me upgrade to a C-29 as soon as it was available. The issues with the mis tracking volume control and other mechanical issues just drove me nuts. Davie Obrien went over the unit twice and the last time he said move on to the new C-29, it will. have fewer problems, so I did. I kept the unit 30 years with out any real issues. You will have to clean the controls annually. C-33 and 34 have much fewer dirty control issues. I love the graphic tone controls. Last time I had my C-34 checked it surpassed specs by a large margin. The C-28 was the last Mac pre-amp to use all discrete components, which I contribute to its smoother phono section. Early units suffered from crosstalk in the phono section. There was a fix for that. My C-34 phono section sound reminds me of my C-28 as opposed to the dryer sound of the C-29. But with graphic tone controls with adjustment of the 150 hz control the two sounds be come identical.. Some thing you can't do with pre amps with the broad stepped tone controls. Love the 1 db steps of the tone controls in my MX 151. But they can't do what the graphic tone controls on Mac Stereo SS pre-amps can do. Its a shame they are not available on tube models. As to C-26 and 27, I didn't like the vol control on the C-26 either. The C-27 fixed that. I just preferred the flexibility of the 28 over the 26 and 27, and the over all sound and freedom of cross talk was improved with the c-29. The C-34 surpasses the older pre-amps easily. C-33 is a close mate. I always found the C-32 to be a little noisy when used with very efficient speakers and 2105's 2125's, 2205's 2150's and 2255's using phono cartridges with below average output. Ortofons with SUT were the quietest because of their high output levels.
 
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I use to switch my DC 300 A's with my C-28 and the contacts on the relay eventually welded to gather. So I bought a Mc power strip that received its current from the wall receptacle and the control voltage from one of the switched out puts of the C-28. I still use it to this day with my C-34 to power the stereo system components.( 2505, MP=100, MR 80, Thorens TD 125, SAE graphic EQ, DBX 119, DBX 3bx, Nakamichi 581Z, Marantz CD recorder, Crown EQ 2, Stax Lambda amp and Signet headphone amp. While the MX 151 controls the 207's and 206 power amps for the HT. and all the digital stuff and video stuff.
 
A 225 had a cleaner top end it seemed to me, it was also more defined through out the spectrum in my experience. My 240's running mono did a great job though. My problem they ate tubes that needed replacing bi annually. The 12 Bh7a were always an issue. The 275 out put tubes lasted much longer, the amps didn't run as hot and that is one reason I suspect all the tubes lasted longer. I switched to SS too soon. It wasn't till I heard MC 7200's and 7100's that I was really happy with SS sound with my speakers. I loved 2255's and 2155s with other speakers. Just not mine. If it were me I'd want a 7100. 324 watts cross 2 ohms. Just over 200 on 4 ohms. Lets see a 2100 match that. They also have power guard that can save you a fortune, have 200 times lower distortion and better signal to noise. But if you have speakers with woofers that are critically damped like the ML series Mac speakers the 2100's bass is well controlled. Have horn loaded or speakers with acoustical labyrinths then you'll wish you had a 7100. If you like tube type bass you will prefer the 2100. Yes different Mac amps sound different with different speakers.
 
A 225 had a cleaner top end it seemed to me, it was also more defined through out the spectrum in my experience. My 240's running mono did a great job though. My problem they ate tubes that needed replacing bi annually. The 12 Bh7a were always an issue. The 275 out put tubes lasted much longer, the amps didn't run as hot and that is one reason I suspect all the tubes lasted longer. I switched to SS too soon. It wasn't till I heard MC 7200's and 7100's that I was really happy with SS sound with my speakers. I loved 2255's and 2155s with other speakers. Just not mine. If it were me I'd want a 7100. 324 watts cross 2 ohms. Just over 200 on 4 ohms. Lets see a 2100 match that. They also have power guard that can save you a fortune, have 200 times lower distortion and better signal to noise. But if you have speakers with woofers that are critically damped like the ML series Mac speakers the 2100's bass is well controlled. Have horn loaded or speakers with acoustical labyrinths then you'll wish you had a 7100. If you like tube type bass you will prefer the 2100. Yes different Mac amps sound different with different speakers.

Wow thank you for taking the time to write such a thoughtful reply! It’s amazing, I feel like with everyone’s reply I learn so many new things. It’s fascinating what you wrote about the c28 and c34. I’m going to audition a c27 from Audio classics. They told me it was made about the same time they were in production of the c33 so it seemed like a safer bet for longevity as opposed to the c26 or 28.

Unfortunately the c34 is a bit out of my price range but perhaps that’s something I can save up for and trade my 27 in for later.

For the time being, would you say the c27 phono section sounds similar to the 26 and 28(minus the fine tuning controls)...and there by the 34 (minus the graphic tone controls)? From what I had seen, the 27 was basically a c26 with upgraded volume tracking and a separate power button.

That’s also a great description of the mc225 - and helpful to know about the mc240 eating through the tubes. I think perhaps down the line, I’ll look into acquiring an mc225.

Btw, your equipment is amazing! Is that your setup in your profile picture? You have the preamps dropped down into the console?
 
@twiiii you used 2x 240’s each as mono blocks? How does mono blocking 2 amps sound in comparison to just running one amp?

For example running 2 mc30 with 2 c8 vs an mc225 through a c22?
 
I've had an MC240 for a while now - never found it to consume tubes inordinately. In one Clinic story recounted by DOB in which (as it turned out) an MC240 that had been brought in that had been on continuously for twelve years. He reported the only service it needed was a new voltage doubler capacitor and a fresh set of output tubes. He made no mention of it needing signal tubes.

PS: Technically, the term "Graphic Equalizer" specifically refers to the type using slider controls - the positions of which form a "graph" of the EQ curve.

The EQ used on McIntosh preamplifiers is properly known as a Rotary Equalizer since it uses rotary controls and not vertical sliders. :)
 
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I've had an MC240 for a while now - never found it to consume tubes inordinately. In one Clinic story recounted by DOB in which (as it turned out) an MC240 that had been brought in that had been on continuously for twelve years. He reported the only service it needed was a new voltage doubler capacitor and a fresh set of output tubes. He made no mention of it needed signal tubes.

PS: Technically, the term "Graphic Equalizer" specifically refers to the type using slider controls - the positions of which form a "graph" of the EQ curve.

The EQ used on McIntosh preamplifiers is properly known as a Rotary Equalizer since it uses rotary controls and not vertical sliders. :)

Great info about the equalizer differentiation! These vintage mc amps - gosh amazing build quality. How have you enjoyed living with the mc240 as opposed to Mc SS amps? I’ve never been able to ask someone who’s actually lived with one of those beautiful amps. I’m having major FOMO about these tube amps / preamps.
 
No kidding - these vintage mc amps - gosh amazing build quality. How have you enjoyed living with the mc240 as opposed to Mc SS amps? I’ve never been able to ask someone who’s actually lived with one of those beautiful amps. I’m having major FOMO about these tube amps / preamps.

To be brutally honest, I never found much appreciable difference between it and the MC2505. The classic beauty of MC225/240/275 is undeniable though.
 
To be brutally honest, I never found much appreciable difference between it and the MC2505. The classic beauty of MC225/240/275 is undeniable though.

That’s good to know actually — perhaps that speaks to the quality of the mc2505. For some reason although I had looked into a mc2105 (probably because I was researching for the 2100) - I never really looked into a mc2505. What a beautiful piece. It never ends — haha
 
If you take your 240 twice a year to a shop with a distortion analyzer and try to keep them the best they can be, you will be replacing tubes regularly.. I did the same with the 275's and would only have to replace a pairs of output tubes every two years or so, while I could end up replacing 240 outputs every 6 months. As for sound the mono 240's sounded better in the bass and midrange, being tighter and more open. The highs were a very close match, but with my live tapes I recorded at 15 ips 2 track the peaks were as compromised as with a single 240. Staging might have been a little better with separate amps, but I never reAlly worried about that. The 275's were better either just one in stereo, or two in mono or two bi-amping. They were smoother less fatiguing with more grunt. Were they a pair of 3500's? Not even close. I much preferred a pair of 3500's over a 2300. A 3500 was a different breed of cat at all power levels from less than a watt to close to 500 watts. They controlled my woofers better than the 240's and 275's too. Listening at 10 to 35 watt levels was amazing. Thats when you discovered what wow and flutter was on a record, seeing the grill cloth flapping in the breeze between selection a nd even worse as the music played some times. It was the first amp to prove to me the most records were really compromised. Only the direct to discs, the Telarc and the Mobile fidelity records really cut the mustard. I wish I had bought 4 of them when I had a chance.

As for the C-34 and C33 they are not the ultimate sounding Mac pre-amp. But they are of a size I can use and have the flexibility none of the modern SS pre-amps have at this time. I'll never go back to the course stepped tone controls of C-22, 28, 29, 27, or the equivalent again. Much preferring 1 or 2 db per step. I love record out selectors, the record processor loops, being able to insert the compander and tone controls in the record loop for other folks, but only using them for playback on my system. External graphic EQ's, limiters, 3bx, 119, auto correlator, and Burwen noise reduction have been used successfully in the past with easy insertion via the C-34. I wish I had room for a C-40, but I don't. Today most folks make up music programs on their computer and touch them up with apps. I'm not ready to go that route just yet. I still make CD back-ups of my downloads and even use more processing than I ever did with analog. Buy a record of Miles and playback a CD or down load. They never sound the same. Some one is always trying to improve on the original recording. Why can't they leave well enough lone. A C-34 allow me to bring back some semblance of the over tweaked digital reissues. Even the remastered LP's you buy don't match the originals. Some are better in some ways with less back ground noise, but in other ways they are hardly the same.

The other day Michael Fremer recommend a recording for some to try. I down loaded the version from iTunes and he was right. This early 60's recording with simple miking was better than DG or Londons attempts decades later. What was ironic, a good friend of mine told me the same thing years later and I didn't believe him. Oh Well we live and we learn. Sometimes the hard way.
 
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Output tube life is a function of operating time and the stress imposed. It all depends on how the equipment is used.

So, say an MC240 used to drive a pair of (low sensitivity) AR3s is apt to need O/T replacements far more frequently than those in the same amplifier used to drive a pair of (high sensitivity) K-Horns - over the same number of operating hours at the same average listening levels.

O/T wear doesn't necessarily mean the amplifier won't be able to make low distortion at all; it simply won't be able to make rated distortion @ rated output spec.

If the speakers are sensitive enough, the loss of maximum (rated) power may never be missed if it's never used or needed. In other words (remaining with the K-Horn example) tubes could be worn to the point that the amplifier may only be good for up to 10 wpc without loss of performance while still providing plenty of headroom with that speaker.

It's not as if performance suddenly falls off a cliff upon the slightest onset of tube wear. It doesn't work that way.
 
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I run a pair of MC240's in mono and I agree with Twiiii's comments on the sound advantages of that setup over a single stereo setup. It makes it a great amp setup over a very good amp.

I own a single MC225 and I love it for what it is: a lower powered, awesome sounding amplifier with an amazing overall balance of tone and wonderful spaciousness. In my opinion, you will need reasonably efficient speakers (>91db) to get the most out of it.

I have had a 275 in my system as well, but didn't notice such a dramatic advantage over my pair of 240's. Perhaps a tad more tightness in the low end.

I also own 4 x MC30's in a biamp setup, but that's a whole other animal.:biggrin:
 
I became obsessed with higher fidelity sound through Jazz - and I remember hearing for the first time the muted trumpet of Miles Davis on vinyl and being emotionally floored. It was on a really bad system, but that didn't matter - the music went beyond the sound quality and that was my gateway drug into this obsession. It felt like I was reading a great book from cover to cover with every record I played. And perhaps because I could not afford to collect first edition books, I began collecting first pressing records. And realizing that many of these artists are no longer with us, it felt like some sort of daily ritual of resurrecting them for the duration of the record...almost to remind myself everyday of their contributions to this life. So naturally I became obsessed with the possibility describing and articulating the sounds of these older performances and cobbled together a budget system on a shoestring budget.

Although the easiest option was to purchase a newer integrated amp via Amazon - like the Yamaha, I thought that for the same cost I could get a vintage McIntosh Amp (something I've for one reason or another lusted after for decades only as an object or myth as I had never heard one in person)

After some searching, I got lucky and ended up purchasing a McIntosh MC2100 via craiglist in great condition and have been quite taken with its performance.

I also purchased with the MC2100 a Yaqin ms23b in hopes of (fingers crossed) getting it modded to the LesMod at some point in the near future. Currently, I have my Thorens 166mkii (AT140LC cart and stylus) plugged directly into the Yaqin ms23b and then feeding directly into the MC2100 which is being played through a pair of Monitor Audio Bronze 2 speakers(bi-wired).

A couple things that I've found myself wrestling with is, do I need a preamp? I've been reading about its original mate the C26 and have also read how most people seem to really dislike it. I've also seen a c28/29 (c29 seems to be more stable than the 26 or 28) paired with it - and visually they look beautiful together.

Does anyone also directly feed their turntable into these types of McIntosh amps? and or have a similar combination of amp/preamp setup? And if so, do you have any opinions on the sound quality difference between direct vs through a preamp?

Also, while on this topic, has anyone paired a tube preamp with the MC2100 which in theory would be kind of like a much nicer or truer version of the what the newer MA252 was trying accomplish. I'm only listening to vinyl and I guess I find myself wondering if need a preamp or if the sound quality will improve considerably...or if I'm just goin to complicate things.

Is there a difference between prephono amps like a lesmod yaqin vs Project tube box, etc?

The final thing is, for those who have lived with an mc225 and an mc240 - is there a considerable difference? If I'm being honest, it was the MC225 paired with a Falcon LS3/5a that I originally wanted but the cost was just too much for me.

Thank you in advance for taking the time to read and respond. I hope this finds everyone well.

The first thing, which I would do would be to replace the 12AX7's with 5751's, known as an audiophiles 12AX7 because they have only 70% of the gain of a 12AX7. Less gain means lower noise and distortion, I have never not preferred them over 12AX7 in any of the gear that I have owned. The 5751 is a US creation, just pick-up a pair of black plates
 
The first thing, which I would do would be to replace the 12AX7's with 5751's, known as an audiophiles 12AX7 because they have only 70% of the gain of a 12AX7. Less gain means lower noise and distortion, I have never not preferred them over 12AX7 in any of the gear that I have owned. The 5751 is a US creation, just pick-up a pair of black plates

Love 5751's, but not sure I agree with the less distortion statement and they aren't exactly a straight electrical swap. They can be less noisy/microphonic due to a more rugged construction. You are correct that the gain factor of a 5751 is 30% less than a 12AX7, but there are differences in plate resistance and heater current draw between the two that may have negative impact on an amp or preamp. It's all gear & circuit design dependent.

That said, I use GE 5751's in a pair of my MC30's and they sound very, very good that way, but really don't like the end result in any of my MC240's paired with various speakers. Haven't tried them in my MC225 yet.

Not to derail the thread too much, but what gear are you using the 5751's in?
 
I’ve owned a MC225 for almost 30 years along with 2 MX110z’s and also had a C28 for about 20 years. I’ve also owned a bunch of other high end tube and SS amps and pre amps. The 225 is my favorite McIntosh amp second only to a really outstanding pair of custom 45 watt tube mono blocks. The C28 compared to the MX110z. The C28 is tighter and more controlled but completely lacks the magic of the MX110z. The MX110’s are scary real sounding and have wondering imaging and just let the music flow right out of them. I sold the C28 and never looked back. The MC225 with an MX110 is always easy and pleasing to listen to. One of my all time favorite combinations.
 
The MC225 with an MX110 is always easy and pleasing to listen to. One of my all time favorite combinations.
Interestingly enough, the MX110 / MC225 wasn't a very popular pairing when the gear was new. MX110 / MC240 sets look to have been sold about twenty to one based on what I've seen in the used market over the last three decades. That being said, my very first MC225 came with an MX110. I'll also agree that the MC225 is the gem of the stereo tube amps - I guess that's why I still have one ...
 
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