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I'm currently running the amp with an Audio Electronics tube preamp. I'm curious what the amp is capable of in terms of clarity and dynamics and I may try a passive pre to see what it sounds like without the the colorations of the active pre.
If other SM-70 oweners are using a passive preamp, I'm interested in knowing what you are using and the results you are getting.
Thanks
Follow Ups:
Thanks for the responses thus far. I think I'm going to start by finding a cheap 10-25k potentiometer to see if I like the result.
Worked well with the Adcom in active, balanced mode too.
Bill Bailey
___
Feanor's list of 250 Core Classical Compositions
I have used an Electra-Print PVA with a pair of SM 70 PRO amps. DAC has 4 volt output stage, so its got a bit of oomph. The PVA uses a pair of nickel core transformers, so its not a true passive.
Sound is transparent and detailed. It can be clinical with the wrong speakers, but overall its satisfying for a SS component.
My other amp is SET, an Electra Print 300DRD.
Regards
Mister Pig
and their output voltage? I'm not sure but you need to make sure you have high enough voltage to drive the amp. In my case When runing my 2.5 volt output Cd player their was no problem, but then driving a low output phono pre, it didnt work to well. WHat I can also tell you is when it matches it clean, fast and dynamic, My warm uninvoliving sounding CD player became alive...
2 volts output. Sounds like you had good results. What did you use for a passive pre-amp?
Thanks
Its a Pro10mc and has a passive circut. All I can say is it smoked a Audio research SP16L in my system...Sold the SP16 after 2 weeks. I ended up going with a $4K PASS SS design after that..It betters the B&K but for 10 times the price of a used B&K it should.
Consider a CD player with variable volume control. My Raysonic 168 has tube output and variable. Sounds great
do have a passive setup myself. The amp has two important "passive friendly" characteristics: high input impedance (100k ohms) and high sensitivity (0.6v). That means the likelihood of HF roll off is reduced and you should have plenty of gain. Remember to use short, low capacitance ICs.
rw
but with a transformer volume control the ICs may not present as much of an issue as opposed to resistive based passives. I use a TVC with an amp that has .8V sensitivity and 67k ohms input impedance.
I've used a single and also a pair of SM-70PRO's on my QUAD ESL-57's using just a 100k pot and selector switch, this is of course not a PREAMP because there is no AMP pre- or otherwise in the control circuit.
It sounded good. Generally speaking the mids and lows from an SM70 PRO sound too "clinical" on an ESL-57; the highs are to die for, but the mids and lows of the ESL57 like a little more euphonious coloration- the SM70 is too accurate, really. I like a hybrid tube amp on the ESL57's, with a little looser bass and that certain "liquid" midrange which is really some kind of coloration you get from the interaction of the ESL57's weird impedance curve with a tube amps' output transformer. With the SM70pro the frequency response seems ruler flat, and after listening to a tube amp which bloats up the midbass / midrange a bit, you get to LIKE that bloat.
Taking the active preamp out and just using a pot and a switch, you hear a little more clarity through the SM70pro, but it's not as big a change as you heard wehn you went from a class AB amp to the SM70. The SM70 itself is the source of audio goodness, and it doesn't seem to be much of an improvement to take all the active stages out ahead of it, unless of course the preamp is some attrotious piece of crap.
I have FOUR SM70's, I use them all over. I am driving the ribbon tweeter of my tri-amped Magnepan MG 3.6 with one of them, and I can't begin to tell you how great THAT sounds. The SM70 is one FANTASTIC sounding amplifier, especially in the higher registers, where bipolar class AB amps all sound really harsh, to my ears. In fact, I use the SM70 to prove to my friends that different amps have different sound. Replacing the SM70 pro driving the ribbon drivers with a good bipolar / class AB / high feedback design and then going back to the Monarchy amps- it is like NIGHT and DAY. The difference in sound is NOT subtle! All the AB / high feedback amps sound like they are generating bursts of noise along with the sound, up in the 6 kHz range. It causes IMMEDIATE "turn it DOWN!" reactions. Playing the same music with the Monarchy driving the ribbons (the xover is 1500 Hz) - at the SAME loudness level as verified by a good SPL meter- and listeners say WOW what an incredible DIFFERENCE! Cymbals sound like shimmering plates of brass and not like bursts of air escaping from a compressor along with breaking glass. People who SWEAR that all amps sound alike ALL leave saying "I guess different amps DO sound different." There has not been ONE SINGLE amp skeptic who has heard this demo who was not INSTANTLY converted to understand that the difference in amp sound is sometimes NOT AT ALL SUBTLE.
of which you speak...
All the AB / high feedback amps sound like they are generating bursts of noise along with the sound, up in the 6 kHz range. It causes IMMEDIATE "turn it DOWN!" reactions.
may also relate to its ability to render low level resolution. The worst example in my experience is the AR integrated amp. It was designed to run full tilt into a pair of power hungry AR-3as. When the level drops, however, the sound quality falls apart. Another amp that generally sounds good, but is subject to this same limitation is the Conrad-Johnson MV-75a. Never harsh like your example, but at low levels it has a blanket over it. When using an amp for tweeter only duty, you are likely never running more than one watt at peaks.
I have an old Threshold Stasis, however, that resolves all the way down to the signal floor. I suspect the Monarchy shares that ability.
rw
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