MV 75

[Pat Rivet]

Hi all,

I'm e recent member and some people of the pre amp chapter of this forum know me after my first post about my PV12 pre amp. This time, I would like to speak about amplifier... As I own now a pair of Magnepan MG1C, my old good MV45 has been sold last week-end. Looking for a more powerful amp, I have the possibility to buy a MV 75. Same "family" I would say, quite same schematic... And so, I would like to know your opinion and experience with the 75. Enough for the Maggies? Reliability? I have to say that I'm near to buy it... As the price suits me!!!
Best from France, Patrick

[AnotherJohnson]

It was an exceptional amplifier when it was introduced over 40 years ago.

IIRC, it was the first tube amp with the easy bias adjustment that has become a conradjohnson hallmark.

It is from the era before it was fully understood how capacitor and resistor materials impact sound. Check under the hood to see if it’s been upgraded along the way. And listen to it before buying if you can.

From the standpoint of owning a really cool and important historical artifact, it’s a no brainer if you are interested in collecting.

It will make the PV12 look positively up to date.

[AnotherJohnson]

FWIW, I like the MV75’s sensitivity spec. It is not super sensitive, which means you are better able to keep the volume knob “up,” which I prefer. As you probably know, when you adjust a preamp to higher volumes, you are actually reducing the amount that the signal is being attenuated.

The sensitivity is the single characteristic that I wish were different for the LP 275M. It is overly sensitive, requiring only .5V to drive to full power.

[admin]

Agree with AJ's statements.

I think the MV75 will be a good pairing. The only possible limitation I see is if you want to play the MG1C at very high volume levels, it begins to get hard to drive as it is a relatively insensitive speaker (I believe 85 db). But realistically, unless you are playing rock music at deafening volume levels, it should not be a problem. At the end of the day you want quality watts over quantity watts, and the MV75 will certainly deliver on that front.

[roberto]

Hola Pat,

The first thing to do on your new MV-75 is: change the power tubes. This will make sure to have them working as new. Power tubes get tired. It is wise to have new ones.

Happy listening!

[roberto]

The sensitivity of the Maggies is circa 86dB/4ohms, so clean power is a must. I love the Maggies...they really are good speakers, but they are really power hungry.

[roberto]

Ask the seller a demo, is it is possible. If you are going to operate the MV-75 as mono amp, you have enough power to drive the Maggies with no problem.

[Pat Rivet]

Hi All,
Regarding the info I have, tubes are new... But I still don't know which ones are on it, NOS or new specs. The seller is far from my house, in the mountains in the middle of France and we deal to be in touch beginning of next year. So, it will be not easy to organize a demo... Roberto, do you mean that a MV75 is a little bit short for the Maggies? Good idea to operate the MV 75 as a mono... except that is so difficult to find a MV 75 i France or in the countries around... So, 2 is quite a dream!!!
Merry Christmas, Pat

[AnotherJohnson]

If the price is good, why not try it and see how you like it? Any speaker benefits from more smooth power, so running in mono is always nice if the budget allows. But how will you know if it’s better if you don’t try the stereo configuration?

This is a 40+ year old design. You are not chasing audio Nirvana. You’re putting together a really cool vintage system. The MV75 will fit right in. Sell it when the budget and ears are best served.

[Pat Rivet]

Price is 1400 $... seems to be honest.
I'm listening US and UK music from de 60s and 70s, Frank Zappa mainly, sometimes jazz, sometimes classic, never really loud... Maximum 9/10 h for the sound's knob of my PV12.
Thanks for the advice and, once again, Merry Christmas, Pat

[roberto]

I used one MV-50 to drive my Martin Logan CLSs long time ago. I had them in a small room so did not have problem with the quality sound. I play most classical and jazz music. Concerts or small philharmonic orchestra and small combos. Also I used moderated level...enough to have a nice stage.

If your room is small, the Maggies will sing nicely with no problem.

If you have a big room, you will need another MV=75 to do the job right.

[roberto]

Also I do believe that having 75 watts/channel is capable to do a very match with your Maggies. Long time ago, I was a Magneplanar user. I had the Timpani 3B. The power amplifiers at that time was the Bryston 4B. I used two power amps connected in vertical connection...good sound at that time. My preamp was a PV-5.

[roberto]

Pat, you are OK with the type of music too. Do your best and get it. It will sound wonderful and also it has a little more power than you're old amp.

[Pat Rivet]

Thanks Roberto
My room is a small one, in my basement. so 2,05 m high, and about 20m2... In the beginning, I'll cope with one MV 75 if I deal with the buyer.
Best, Pat

[Pat Rivet]

Message to the "Magnepan expert", Roberto and, I'm sure, some other guys...
I have also a studio professional gear, a german one, K+H Telewatt, from the mid 70s, with 100 W per channel. So, it could maybe be possible to use it, beside the MV75, for a bi amplification, the MV 75 for medium and treble. But I don't know how to proceed. I red somewhere that it's easy with the Maggies... without using any crossover, which is very strange for me... Or, do I really need to find a XO-1 crossover, which is, now days, quite impossible?
Any advice will be, once again, much appreciated.
Merry Christmas, Pat

[roberto]

Hola Pat,

The sensitivity of the power amp must be about the same as the MV-75. You can use it as you suggested. The operation of the magneplanars, the are connectors at the back of the speakers. This connectors are jumpers between the bass-midrange panel and the tweeter panel.

If the German amp has volume or level control is easier to use, because you can match the level between the midrange-bass and the tweeter. I dunno. I will use the CJ driving the bass-midrange and the German the tweeter.

I will try to use the MV-75 without bi-amp and have a listen. I think that it will drive your baggies without any problem and a good clean level.

[roberto]

When I had my Timpani 3B, the bi-amp that I used were the same brand and same model. This assure the level sensitivity matched. Some amplifiers, their sensitivity might cause level imbalance. Having an electronic crossover, you can adjust the level of the bass and the mids and highs. Read your baggies instruction manual. There you can learn better the procedure to do it.

Again, my suggestion is to use the MV-75 as full range. If you have a second MV-75 you can use vertical connection, this is one amp driving one channel, and the left channel MV-75 driving the bass-midrange and the right channel driving the tweeter. Same connection for the right channel.

[Pat Rivet]

Understood. Thanks!
Best, Pat

[admin]

I agree with Roberto. Full range is the way to go, especially if you don't have the same amp models. I don't like fancy external crossovers in systems, I rather keep the signal as pure as possible and most high end speaker manufactures are going to do a better job at designing the crossover for a specific speaker than we can come up with so why mess with it?

[AnotherJohnson]

If you’ve got two MV75s, vertical biamping is a good strategy, but this is often true. In my experience, most speakers benefit from more power up to some limit.

Running a great speaker with more power than recommended doesn’t lead to problems because, at typical home volume levels, you are less likely to get clipping, which is always hard on speakers.

But again, you won’t appreciate extra power unless you know what the lower power sounds like. Often it is really very nice, and the only incentive to add power is based on curiosity. But often curiosity is rewarded.

My lesson has been that, in my own case, 250 wpc into 4 ohms seems like the minimum price of admission to audio Nirvana. YMMV.