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Ever since I heard Manley lab tube amps at Stereophile Show in 2004 I've been curious about tube amps. However, my taste is speakers seem to be at odds of what tube amps are designed for i.e. high efficiency low drive count units. My speakers are 88db 4ohm Polk Audio LSi 15 driven by a B&K 400watt in the 4Ohm beast. Is tube amp not for me?
It's hard to have hands on research locally, not many dealers carry tube. One of the dealers that carries McIntosh actually discouraged me from going with McIntosh tube amps in favor of solid state. He says that are too much hustle. But at the same time he really pushes turntables, lol!
Would I be better off having a tube preamp with a solid state amp? The only thing I really don't want to introduce a separate preamp into my HT/Music system...
Follow Ups:
Manley makes great stuff... and the Snappers are wonderful but I didn't like the power switch in the back.I'm driving my Marten Design Dukes (87db,8ohm) with vintage Manley Lab Series mono 100's w/ MOS Mullard EL34's. Even with a passive preamp (Bent NOH)they rock!
And since someone mentioned Dynaco, in a second rig I'm driving my Dynaudio Special 25's (87db,4ohms) with Dynaco MKIII (via Will Vincent) also with a passive preamp.
Go with the Snappers. you'll love them.
Tony
Edits: 04/15/10 04/15/10
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drive low impedance loads quite well. They are optimized for a nominal 5 ohm output, but mine works fine with the hellish low impedance load of electrostats. It is all about the transformer.
rw
I have driven various Magnepans with tube amps. I've liked the results plenty well. Way back when, I did use a stock ST-70 occasionally to drive a pair of MG-IIBs. I recall this as sounding just fine most of the time. Really cranking things up didn't always go so well. Things got soft and compressed, and occasionally a bit worse.
I haven't had any issues powering speaker as inefficient as Maggies, and those speakers more efficient than the typical Maggie, with tube amps in the 70-150 wpc range. I haven't typically spent that much time looking at nominal impedance and impedance curves.
I would guess that a Cit II would be very nice, the Manley Snappers could possibly be fun, etc. Lots of choices.
- SJ
I drive my less than efficient Thiel CS2.4 speakers with the Manley Neo-Classic 250 monoblocks and I love the way this combo sounds.
My first EL34 tube based amps where the 50wpc AES/Cary SixPacs that drove my more friendly Tannoy D500's rated at 6 Ohm nom. / 91dB sensitivity. But the Thiels need a lot more power so when a buddy of mine put his Manleys up for sale, I snapped them up.
He has a habit of driving speakers with amps some would consider too low in power for their efficiency but he was happy with his Dynaco and those low efficiency speakers for years and years (and he used to sell audio equipment at one point in his life). I heard them many times and power and head room were never a problem. I drove 89-90 db speakers with a Dynaco for years myself. I am not recommending a Dynaco for your speakers as a first option if you have more money, but there are tons of tube options that will easily dive 88db efficient speakers. A Dynaco MK III, Citation II, Antique Sound Lab has some options that won't require modifications, etc...
I am not sure what your budget is but look at any of the Octave amplifiers. They are rated to drive speaker loads down to 2 ohms. I have heard several models of these amps drive big speakers with low impedance curves. They are not very well known in the states yet, they do magic on a pair of B&W 800's I am driving them with MRE 130's, 140 watt mono blocks. Music is crystal clear and so palpable. I am just a happy owner of these products. Dynaudio is the distributor in the states.
http://www.octave.de/en/htdocs/verstaerker/v70se.php
If you are in the area and these products fit your budget, do yourself a favor and listen to these amps. They are really great.
Ciao,
Audioquest4life
Hi,
As Eli said, a fully restored "McShaned" Citation II would drive them easily. If they don't dip below maybe 3 ohms then most any decent tube amp with a 4 ohm tap and 60+ watts per channel will probably drive them. I'd be wary of any dealer who thinks that tubes are too much hassle. He clearly doesn't know much about them and probably shouldn't be carrying them if that is the case. Go to the polk audio site and look up the impedance curve for your speaker and see what they specify the lowest point to be. As long as it is 3 ohms or more then a tube amp can drive them. Eli is pointing out the worst case scenario. As he said, a Citation II can drive them very nicely as it is stable into a 1 ohm load. And better than most any other tube amp you are likely to encounter.
don
FWIW, my 1980 vintage AR-9s are 87 db efficient (that's at one watt), meaning 87db with 1 watt input at 1 meter on axis.
A "McShaned" Citation II will drive them to uncomfortably loud levels in a moderately sized room. And do so without sweat and strain.
One of my most memorable experiences was when a gentleman (Terry - I can't recall your last name if you are reading this) came by in person to pick up some Citation parts. It turns out that his business was restoring pipe organs! So of course it was a mix of dread and anticipation occurring when I played him the finale from the Saint-Saens Organ Symphony. Afterwards I asked him if what he'd just heard sounded anything like a real pipe organ - he immediately replied "oh yes, that was remarkably good".
Believe me, that takes STONES from the amp.
And a small correction on Eli's statement - I routinely see 150 watts plus of peak power from a "McShaned" amp.
I can't recommend a Citation II more highly for your system.
Guys, thanks you all for great help. I guess I should be able to explore tubes as a viable option for my setup then. What is the opinion about Manley Snappers - they are 100 Watt monobloks. They have been making them since 2002 and seeing how they have updated every other model, is it possible Snappers are due to update as well? Maybe even more power?
By the way. What is the biggest difference in sound when going from solid state to tube amp? My B&K is pretty smooth sounding solid state amp.
"What is the biggest difference in sound when going from solid state to tube amp?"
Better midrange.
"What is the opinion about Manley Snappers - they are 100 Watt monobloks."
I know nada about those Manley units. However, it is a fact that O/P trafos make or break a tube amp. The "iron" used in the H/K Cit. 2 is a prime contender for the best ever wound. Open loop bandwidth is well above 100 KHz. :> D
Eli D.
Very few speakers are more than a vintage Harman/Kardon Citation II in good repair can handle. Large Thiels, with their outrageous impedance dips are 1 of the rarities. A "Duece" done up ala Jim McShane can produce a bit more than 60 WPC continuously and over 120 WPC instantaneously.
Polk claims 88 dB. SPL for 1 W. of drive at a 1 M. distance. The $64 question that lingers is it really 1 W. of drive or 2.83 V. of drive? A 2.83 V. drive signal into 4 Ω is 2 W., not 1 W. Let's assume the worst and that Polk "spins" the numbers, like so many other manufacturers do. In which case, the "true" efficiency of the LSi 15s is 85 dB. Paul Joppa has given us a useful rule for mating speakers and amps. Joppa's Rule states that in an "average" listening space an amp/speaker combo should be capable of producing 102 dB. SPL peaks, at a 1 M. distance. Applying the rule to 85 dB. efficient speakers yields slightly less than 64 WPC. No matter what, a H/K Cit. 2 refurbed ala McShane has the cojones needed to mate with your Polks. :> )
Eli D.
Most dealers do not know much about tube amps. Purchase a tube amp with 4-ohm speaker taps. You will likely require 60-watts per channel due to the lower speaker efficiency. Perhaps less, have not studied the speakers ohm curves at various frequencies. Others can likely assist in the power requirements better than I.
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