Magnepan 20.7's & Tube Amp


Not looking for options beyond the two tube amps below.  I am only considering one of the two to drive my Magnepan 20.7's.  Would either drive the 20.7's well?  Do they provide enough bass? Is one better than the other for this application? Thanking those of you in advance who can assist me here!

PrimaLuna Dialogue Premium HP with KT150's / 88's as Monoblocks

or

Audio Research VM 220 Monoblocks

1985tqc
Depends on the size of the room, type of music, and how loud you listen to your music. That said, the closest experience I have is driving 3.7 model with Cary SLM-100 @ 100wpc, in an average size room and I felt the speakers were starving for current at medium to high volumes. 
which one has more amps into 4 ohms?
which one has more amps into 4 ohms?
This is a bit of a trick question.

The amount of current will depend entirely on how much power the amp makes into 4 ohms. If 200 watts, the current will be 7.07 amps regardless of the amplifier involved, tube or solid state.

Wendell Diller always made a point of telling me that the best he every heard that speaker was at Johnathan Valin's house using a set of our MA-2s. What we found with Maggies in general is that if you want to play the speaker with tubes, keep the speaker cables between the amp and speaker really short- over a foot is too long! Place the amp with the speaker terminals facing the speaker's terminals and install the really short speaker cables.

This is a really good place to have monoblocks :)

Anyway, this gets you the best bass. Don't worry about vibration from the speaker; the amp will see very little. Maggie owners know what I'm talking about.
Ralph, wouldn't a set of Zero Autoformers be of help?
Bob
Ralph, wouldn't a set of Zero Autoformers be of help?
The MA-2s don't care, but on a lot of amps, yes. We are in Magnaplanar's back yard up here in the frozen wasteland, so we have a good number of local customers running M-60s on some of the smaller Maggies, and the ZEROs are how they do it.

Paul Speltz has a letter from Steve McCormick in which Steve states that although his amps have no problem doubling power into lower impedances, that they actually sound better if they are driving 4 ohms through Paul's autoformers (the ZERO). So the ZERO's help with a lot more than just our amps.
A Big high current  solid state amplifier would have much better grip ,control 
On the Panels.  I have used big Bat amplifiers  and the Pass labs 250.8 would be a 
A match as close to Ideal as you can get.  With s good tube preamp.
Even if not was not mentioned it should have been if you want to heard the truth. 
Im using 2x Parasound A21 for my Maggies but still have to run two little mj acoustics subs to give it that extra ooph
Ralph, is the need for the very short speaker cable unique to the planar/OTL combination or long cable inherently causes low frequency roll-off? I didn't think the cable length should be that detrimental given a 1.75 ohm output impedance on the MA-2.
When I had a pair of M-60’s powering my old Quads, I did exactly as Ralph recommends: the rear of each amp facing the back of each speaker, with a 1’ length of wire (silver Kimber) connecting the two. So much for cable makers who say with a straight face their wire should be no shorter than 6’/8’/whatever. Pure BS. A very real benefit of mono amps and short speaker cables is that you can then run balanced from your pre to mono power amps.
Ralph, is the need for the very short speaker cable unique to the planar/OTL combination or long cable inherently causes low frequency roll-off? I didn't think the cable length should be that detrimental given a 1.75 ohm output impedance on the MA-2.
The issue is that tube amps generally speaking have a higher output impedance than solid state. When you add a long speaker cable, the cable is a series resistance added to that of the output impedance of the amp. It may not seem like much, but fairly small resistances like that can have a big effect when the impedance of the speaker is already pretty low.

(This is one big disadvantage of 4 ohm speakers- the cable becomes really critical! You also have to make sure your connections are good and tight.)

So the simple solution is to keep the speaker cable short. I really don't think it makes a difference what tube amp is used (as long as it make a satisfying amount of power)- the speaker cable should be as short as it possibly can to make the connection. I think a foot is about as long as you want. I've heard this make a profound difference in the bass impact on several different Tympanis, MG3s, 20.1 and 20.7.

We use 10Gauge copper OFC speaker cable, using both conductors joined together at both ends by a single heavy speaker lug.  So we have to build up four such jumpers but it really pays off.

A Big high current solid state amplifier would have much better grip, control On the Panels.
I don't find this to be the case. What seems to be happening is that the lower output impedance of higher powered solid state amps allows more leeway with the series resistance of the speaker cable. We've been running fairly high output impedance amps on Maggies for decades and they seem to 'control' the panel just fine with plenty of bass impact. So I regard this as a common myth, caused by a misunderstanding of how critical the speaker cables become when you run 4 ohms and use tubes. Put another way,  if you compare a tube and solid state amp on the Maggies and you also have longer speaker cables, its likely the solid state amp will have more impact. But if you use really short cables the differences between the amps will be less profound. 
Have you looked at the Carver 350?  They're supposedly amazing with the 20.7's.
BTW, I have a pair of Zero's for sale on the gon right now.

ozzy
I bought a pair, but haven't hooked them up yet.
I am just curious as to what they can do, considering what Steve McCormack said. SMc just made me a pair of monoblock DNA-1's with the express design to outdo Ralph's MA-1's (hey, they get too hot in summer). We'll see....
When things get settled in, the Autoformers will be an interesting experiment.
B
I Just spoke to Wendell Diller at Magnepan and reducing the speaker cables has zero affect unless your running 15-20ft of cable. I don't know why we get all this misinformation on Maggies. I use tubes 110w and they rock. I traded in my ARC DS450M monoblock for ARC REF110 and my 3.7i never sounded better. Please stop the madness and enjoy your Maggies.
@bluesy,
Ralph (atmasphere) knows what he is writing about.
And, though you are enjoying the sound from your system as it is, I would invite you to try using a short cable and see if you still feel the same.
Bob
@gdnrbob I don’t doubt it but I’m going to trust and believe Wendel Diller. I also have no desire to cut a pair $8k cables to prove a point.
The original discussion was about 20.7 and not 3.7. And in general, I tend to put more weight on inputs from practitioners than from the manufacturer. To each his own.

@kalali

I have a upgrade option for the 20.7i and I plan on using it so my interest in getting this question answered was twofold. So this weekend I went to my local retailer and heard the 20.7i with 10ft of transparent cables using ARC 250SE monoblock amps and again they sounded amazing with great bass and a extended 3D sound stage. Listened to jazz, classical and female vocals. Ginger Baker ’Cyril Davis’ drum kicks and Stevie Ray Vaugh ’Tin Pan Alley’ was absolutely unreal. So like you I don’t care about what others say I heard with my own two ears. I will be upgrading my 3.7i to 20.7i next month and will not be concerned about my 8ft length of Tara Labs 0.8 speaker cables. Again to each his own.

Congratulations. Your 8’ cables, especially of such high quality should not pose an issue but a pair of ARC 250SEs as compared with an ARC Ref110 may give you different results. I’m sure I’m stating the obvious but you may want to try the larger Magnepans with your amp if the dealer is local. Nothing to lose and just gain a peace of mind.
I Just spoke to Wendell Diller at Magnepan and reducing the speaker cables has zero affect unless your running 15-20ft of cable. I don't know why we get all this misinformation on Maggies.
We've built short speaker cables for a number of our customers who are really happy with the results. I would not want to cut an $8000 cable either!

But the difference was not trivial- shorter cables really help if you are running tube amps.
@kalali,
Funny, but I take the word of manufacturers before practitioners. First, they have more experience. Second, why would they lie?
With regards to speaker cables, it just makes sense that a short run will be better than a long run, when you look at the basic physics of electrical current. There is that nasty thing called Resistance. And, every cable, even $8K ones will be affected by it.
Bob
I have zero quarrel with Ralph and I always read his posts with nothing but respect. The short speaker cable with monoblocks suggestion is also one touted by Mike Sanders of Quicksilver, and Mike Sanders gets widespread respect from all on both sides of the fence as well (needless footnote; aren't we dealing with tri-compartments like our knees-manufacturers, retailers/distributors, and consumers?). But that said, I have come around to viewing speaker cable and IC's as sometimes being necessary evils. Sort of like salt-a necessary spice that can cause harm but can also add much to the pleasure. Sometimes due to the inherent qualities of the components, lack of any cabling renders the sound like an unsalted pretzel. Pure, but not one I care for.