I have not used OTLs but the best Triode operated amps
from VTLs or Antique SoundLabs (try Hurricanes) should do these well. I own the QRS and Genesis II.1s and the ribbons are driven phenomenally well, beautiful, is the word with
VTL 240s which use 807 tubes in triode configuration for
arround 100 watts per side. |
Genesis ribbons are fairly stable 4 ohm loads with a bit of trouble in the 85 to 200 Hz area that is taken care of by the crossover. OTL's might not be the best choice because they are designed for 8 to 16 ohms, usually. Some of the bigger Atma-spheres have no problem with 4 ohms. One thing to consider on the OTL's is the cost of retubing every few years. There are tube amps, like Manley that are designed for low ohm loads.
I have heard people swear by both SS and tube amps for the Gennies but they all say they like lots of power. Not sure if speed is an issue but tubes usually have a slew rate much slower than SS. Edge and Monarchy make some of the fastest nowadays.
http://www.atma-sphere.com/papers/myth.html |
I have driven my Magnepan 3.6's (which have a vertical ribbon driver) from the Atmasphere MA-1's and the MA-2's, both with and without the auto-transformer. To make a long story short, the sound is spectacular with the auto-transformer. It is detailed, liquid and without any grain or harshness. It is a superb match and without introducing any anomalities. Without the auto-transformer the sound is still excellent but, the response is a bit uneven. There is a little bloat in the midrange and, perhaps a slight downshift in the extreme treble. This is more true with the MA-1 than MA-2. No doubt this is due to the rather significant internal impedance of the amplifier starting to affect the overall speaker crossover impedance. |
None of us listens to a tube or a transistor alone; It's the implementation, i.e. the amps, we listen to.
One good thing about tubes is that a circuit can be stabilised w/out feedback thus eliminating extra "length" in the signal path. Another is that, given the lowish output in these circuits, one can build a tremendous driving "engine" (i.e. trannies & rectification and energy storage) to accommodate those few watts.
As Eldart pointed out, tubes can easily go into the MGh region just as transistors -- they just have high output impedance to drive devices like spkrs directly (unless you parallel them & then some, see OTLs).
Likewise, a transistor amp, designed to cover a wide bandwidth should do well -- as long as it doesn't have severe phase problems (i.e., the time window for a 0,5MGh signal is much smaller -- i.e. you have to rise & fall faster in time -- than, say, a 500Hz one).
BTW, if I'm not mistaken, Mr Berning doesn't use output trannies in his basic designs... |
Berning did a presentation several years back to fellow Physicists at a convention, where he proved that tubes measured faster than SS devices, so much so that the SS measuring device that was used, showed the tubes was faster than the measuring device was supposedly possible to measure! |
"fast organic liquidity with dynamics at around $4000 and hopefully much less(new or used)-- again specifically driving ribbon mids and highs?"
I don't know what associated equipment you were using with the bryston maggies or what your musical tastes are. I was listening to the Mark Levinson CD 39, 38 preamp bryston 7b and the ribbon tweeter maggies. The CD was Branford Marcellus duet with his father. So good that the salesman went out and bought the cd.
I think the 7b's were about $4k.
If you want to go all out like the $10k-27k atma spheres'. We can have a shoot out tube vs solid state.
If you pay attention, I have nothing but praise for the atma spheres. Wouldn't mind owning them myself. Those tubes must produce a beautiful glow at night. I just think transistors offer more speed than tubes. If you don't mind the softened transients of tubes please be my guess. |
A very interesting thread as I will soon have an opportunity to listen to the Atmasphere amps with Electrostatics (SoundLab) and hopefully my Magnepan 3.5s if the dealer will allow me to lug them to his shop.
As for the suggestion to stick with ss for ribbons because of the lack of "speed" with transformer'd tube amps, I just have to disagree here. I did indeed hear the Magnepans at my dealer (Minneapolis) on both Bryston and ARC amps. It was absolutely yawn city with the Brystons. I just don't get it with all the praise from people using these amps with Magnepans. Without the "you are there" feeling, who cares about speed!
The Maggies bring on an incredible emotion to the music when driven by a number of tube amps that simply is not there with the Brystons. The hybrid (tube input / ss output) Counterpoint NPS400 far exceeds the Brystons in a most natural tonal balance and resolution. But the Wolcotts bring on a whole new level of natural decay of notes and 3-dimensionality beyond the Counterpoint.
I have no idea the quantity of "speed" of the Wolcotts. Until I hear an ss amp that can do what the Wolcotts can do, I will stay with what I have. And from what I have read from Rushton's many responses here, I can only imagine that the Atmasphere's would be another huge leap in this direction.
John |
It seems I just discussed this with Albertporter. I recommended that he consider the atmaspheres for his ribbons or for the ultimate in speed consider solid sate. I made the speed decision based on my audition of the Martin Logan Statement latest version dirven by Spectral electronics. Albert presented proof that his vtls were plenty fast. He is currently running Air tights on top.
If a picture is worth a thousand words a listen is worth an endless discusion. Get thee to a dealer and have a listen to the Bryston 7b with the magneplanr 3.6 or 20. |
Hmmm..., LPs do have signal response above 20KHz... In fact, this is one of the challenges for well designed analog front-ends: the cutting lathe can place a very high frequency sounds, including harmonic distortion, into the record grooves that then have to be dealt with effectively, for good and ill. For some spectral analysis graphs, see: http://users.bigpond.net.au/christie/comparo/part4.html. |
In a tube amp, it's the output transformer that limits frequency response. Tubes themselves function nicely at RF frequency, and so do transistors for that matter. With an ultralinear circuit (with transformer secondary taps for feedback around the transformer) tube amps with transformers can be made flat to at least 20 KHz, and it is arguable whether higher response is necessary, since neither CDs nor LPs have signal content above this. SACD and DVDA may have higher frequency signals, but the audible effect is also arguable. |
AtmaSphere M60s have been a great match with my Raven R3.1 drivers. |
Gregadd, I'll beg to differ with you on one point you make: "Tubes are too slow to get the speed out of ribbons." One of the reasons OTL tube amplifiers are so good with electrostatics is precisely their speed. OTL tube amplifiers have incredible speed throughout their frequency range, coupled with high resolution and transparency; the impedance of the speaker is the only issue in how good a match there will be (and with an OTL like the Atma-Sphere MA-2 impedance is not much of an issue unless it's dropping sharply below 3.5 ohms or so). Whether a ribbon will be a good match for an OTL will be a function of impedance matching, not speed. Since many electrostatics have rising impedance curves, and since OTLs are happier with high impedance loads than are solid state amps, it makes for a good combination. I just don't know about ribbons.
As to solid state versus tube OTL speed, I'd match the speed of an Atma-Sphere MA-1 or MA-2 to that of the best solid state amps any day, the solid state amps certainly don't surpass the Atma-Sphere as to "slew rate" or "rise time" (rated at 600 volts/microsecond, matching the Spectral solid state amps which exceed almost all others).
As to traditional transformer-based tube amps, I'll agree with you based on my listening, but I personally prefer any number of them to ss for other important characteristics.
. |
Gregadd,
I 'm a bit confused with the "solid state OTL" statement. All SS amplifiers are Output TransformerLess (OTL) with the exeption of McIntosh amps that use autoformers at their output. As for tube amps being generally slower, I guess it could be true for some. However, tube OTL's are devoit of the one device responsible for slowing them down and that is the output transformer. The atmasphere amps in particular are regarded as some of the fastest sounding amps period, with specs such as rise time and frequency response that bear this out on the test bench as well. The only requirement is that they be used with loads that don't dip much below 8 ohms. |
OTLS are best with electrostatics. Theoretically they should work well with ribbons. My personal opinion- ribbons go with solid state. Tubes are too slow to get the speed out of ribbons. Happily there is a solid state OTL. The name escapes me now, but I'll find it. |
OTL compatibility will depend on the minimum impedance and how steep the curve is. For the Atma-Sphere MA-1s, call Ralph Karsten at Atma-Sphere for advice. He can probably tell you if he's got any customers running this combination and how well it works. http://www.atma-sphere.com/contact/index.html. |
Atmasphere MA II.2 has been reviewed in the absolute sound driving Genesis 350 SE with good results the review is available online somewhere? never heard them myself. They're more expense than your indicated budget although. Would suggest VTL 450 signature the latest most current version with infini caps I actually preferred my not current version 450 to the Walcott presence amps I also previously owned especially using VTL in triode the newer version is much improved by the infini caps. The Walcott is little more difficult matching your system synergy as its less forgiving of cable matching issues than the VTL is.
your cello may sound excellent definitely try it. |
