Mcintosh amp advice

[Yggdrasill]

I have a friend who has a pair of Martin Logan Vantage speakers. He listens to really high volumes and is looking for an amp capable of driving them. He bought some Marantz MA500 monoblocks on Craigslist but even bridged (2 amps per channel) they go into protection. Evidently the Vantages can demand down to 1.7 ohms.

He has about $3k to spend. Can anyone recommend a Mcintosh power amp that would be comfortable with this kind of load, in the 200W range and up?

Thanks. Thor.

 

[CruzBay]

In bridged mode the Marantz amplifiers can't deliver the current to the speakers, they're probably very close to popping fuses or catching fire bridged into a load like that.


Any Mcintosh autoformer-coupled amplifier would drive those speakers, on the inexpensive side, a MC-2200 would be fine.

-edit- 3K (or a bit more) might net you one of these;

at which point your speakers would be in danger of catching fire.

 

[whoaru99]

Yes, bridged mode is even worse for amps if the impedance is very low. A speaker that goes to 1.7 ohms will be felt as 1/2 that value, or roughly 0.85 ohms, to a bridged amp. No wonder they're going into protect. Very few amps will be happy with a load like that in the bridged mode.

That the Marantz amps are still working should be a testament to their robustness, or at least that of their protection circuits, rather than thoughts of inadequacy. They were never intended to deal with anything like that, I'm sure.

 

[skippy_ps]

MC-252 or 352.

Murray

 

[nsgarch]

I have a friend who has a pair of Martin Logan Vantage speakers. He listens to really high volumes and is looking for an amp capable of driving them. He bought some Marantz MA500 monoblocks on Craigslist but even bridged (2 amps per channel) they go into protection. Evidently the Vantages can demand down to 1.7 ohms. He has about $3k to spend. Can anyone recommend a Mcintosh power amp that would be comfortable with this kind of load, in the 200W range and up?Thanks. Thor.

I drive my ML CLS IIZ's with a SINGLE McIntosh MC275 (90+ watts/ch). I could blow out your ear drums with it, and without the MC275 even soft clipping. Now hold onto this bit of info while I compare the CLS panel's specifications to the Vantage panel's specifications. (Don't worry, it's apples-to-apples because with a Vantage, the extenal amp, whatever it is, only drives the panel, same as a CLS.)

• The CLS panel is almost 1100 sq.in. vs. the Vantage 400 sq.in. -- in other words, almost 2-3/4 times larger than the Vantage panel.
• The CLS's sensitivity is 86dB vs. the Vantage's (much better) 92dB.
• The CLS goes down to 40Hz vs. the Vantage which only goes down to 400Hz where it crosses over to the built-in self-powered woofers.

So on all counts, the CLS panel should be much harder on an amplifier than the Vantage panel, at a given SPL. Also the CLS can drop to even below 1 ohm at 20KHz (although to be fair, we should remember there's not usually much loud program material at those ultra-high frequencies.)

I agree with both whoru99 and CruzBay that bridged SS amps can have serious problems driving low impedance loads, but this doesn't seem to be true with tube amps (as they're already transformer coupled). Which is why when driving electrostats, one needs a solid state amp of at least 1.5 times the rated power of a (conventional) tube amp to achieve roughly the same level of performance. And this is not me 'speculating' either -- I used my Levinson 200w/ch 23.5 in rotation with the 90w/ch MC275, and they were pretty closely matched performance-wise (although admittedly I'm partial to the sound of tubes with stats). The point I'm making is that (at least with electrostats) a tube amp will keep supplying the necessary current as the load impedance begins to drop, while the current (not the watts) coming out of a solid state amp (bridged or not) begins to slide as the impedance of the load goes down and its watts/power (on paper) begins to increase.

And let's not forget that Peter Walker drove his original Quad ESL 57 (whose impedance drops at a very demanding 600Hz!) with 15 watt Quad tube amps for years before SS came along!

My message is that with either full range stats (like the CLS) or the new ML hybrids (like the Vantage and Summit) where the amp doesn't have to drive the woofers, one is free to choose an amp that is best suited for driving JUST the electrostatic panels (which those Marantz definitely are not ) And also, that "best suited" does not necessarily mean "more powerful", unless you are only going to consider soid state amps.

I know at least a half dozen people who drive Vantages with just one MC275. (The Summit people tend to use two of them bridged ;--) And your friend should be able to pick up a really nice used MC275 Mk IV or V for $3k or less.

.

 

[Yggdrasill]

Thank you everyone. Really helpful replies. I had no idea of the advantages of tube vs SS with low impedance loads. My friend is going to have a look at the MC275. He bought his speakers at Magnolia so there should be no problem for him to do a demo there, as they're a Mcintosh dealer.

 

[whoaru99]

I believe it is not a SS vs tube thing, merely a function of amplifiers capable of handling low impedance loads or not.

IMO, if listening at really high volumes is the thing, I'm not sure a MC275 would be the right mix with 86dB speakers, although "really high volume" doesn't mean the same thing to everyone.

 

[TNRabbit]

Sunfire Signature series amps are capable of handling the load your talking about at very high output (the 2 channel signature model is 600 watts into 8 ohms, 1200 into 4 ohms). I WOULD NOT recommend bridging ANY amp into that speaker.

I currently bi-amp a pair of Carver Amazing-III speakers with 4 channels of a Signature 400x7 channel amp with great success (4 ohms nominal impedance, dipping to 1.8 ohms at certain frequencies).

The Carver Silver 7t and 9t monoblocks would be up to the task (575 wpc into 8 ohms) as would the Carver TFM-75, but they are more difficult to find.

 

[nsgarch]

I believe it is not a SS vs tube thing, merely a function of amplifiers capable of handling low impedance loads or not.

Yes, theoretically that's true, but the electronic facts of life also tell us that a conventional tube amp (push-pull/output transformers, etc.) will deliver more current, watt for watt, than a ss amp with the same gain. (I'm not sure if a SS amp with output autoformers might represent an exception to that.)

IMO, if listening at really high volumes is the thing, I'm not sure a MC275 would be the right mix with 86dB speakers, although "really high volume" doesn't mean the same thing to everyone.

Everything else being equal, obviously, at 92dB efficiency, the Vantage should be able to get louder than the CLS at the same power/frequency. However, keep in mind two things:
1.) The diaphragm of the CLS is much larger, and thus it moves more air with each watt; and then there's the problem that measuring electrostat efficiency is essentially impossible, using the standard dB/watt/meter, because at one meter away, you're hardly looking at the whole diaphragm! )
2.) Neither the CLS nor the Vantage put any low bass (power) demands on an amplifier, although for different reasons: the CLS can't (its bass response falls to virtually nothing by 40Hz :yes and the Vantage crosses over to the woofer's amps at 400Hz.

Although my listening room is not huge, it is a modest size/volume, and it's amazing how loud one MC275 will drive the CLS's -- although, I admit, if I had the space and the money, I'd want to try two MC275's in mono :yes:

 

[whoaru99]

Yes, theoretically that's true, but the electronic facts of life also tell us that a conventional tube amp (push-pull/output transformers, etc.) will deliver more current, watt for watt, than a ss amp with the same gain.

It's probably just a difference in how we explain things, but I see similar comment every so often but I don't understand it. To me, the relationship of the watt is tied to the load (speaker) and the voltage the amp develops on the load, and doesn't vary for any given point.

It doesn't matter, IMO/AFAIK, if the amp is SS or tube, if the amp is putting 10 volts to the speaker, there is "X" amount of current regardless of the amplifier topology. I guess put another way, the relationship of volts, amps, and resultant power can't arbitrarily be mix-matched (1V x 10A = 10W or 10V x 1A = 10W) when considered in a non-abstract sense where the speaker/load is the common element.