Class D amp with Tube Preamp Combo?

Have you ever tried a good class D/T amp & tube preamp combination? I have read their can be some occasional problems matching these together?

I was thinking of going this way to get the drive, clarity and efficiency of the switching amp combined with the warmth and full body of the tube pre amp.

What setup are you using?

My first post by the way! I have been reading this forum for the last two weeks learning about audio and what to buy for my first serious system.
I have a Modwright tube pre-amp and Bel Canto M300s driving Von Schweikert VR-4. The IC runs are 15 feet. I have had no problems whatsoever. I contacted both Bel Canto and Dan Wright prior to purchase and they both assurred me that it would be fine. They were correct. It is a beautiful combination and trouble-free. You do have to match the impedances. Contact the manufacturer if in doubt. For instance, Upscale Audio did not recommend the Prima Luna tube pre-amp with the M300s because of impedance mis-matching. Good luck
If you can get a good impedence match, use balanced IC runs and the amps have good RFI/EMI rejection, then it can work very nicely. The Bel Canto is one good choice. Also look at Jeff Rowland Design Group and Spectral for amps that do all the above.

I have the Supratek Chenin tube preamp (modified to use 7193 tubes instead of 6SN7) running into the Gilmore Raven Class D amp, powering Zu Druids/Mini Method sub. I think it sounds great! Crisp, clean and very powerful.
yes, i going the Bel Canto s300 to power a set of PMC TB2's. I now just have to find the pre-amp. I need 220-240v though where I live. 2 line outs as well so I can run an active sub too in the future.

I have been researching, Rogue, second hand Conrad Johnson, some good things said about Juicy Peach (funny name) I like the look of the Modwright company, are they expensive. There are so many company's I have never heard of. Where does the worm hole stop?
Hi Dave, did you mean Spectron digital amps rather than Spectral? Spectron Mus 3 is a fabulous switching amp!

In answer to the original question, I have heard several times Bel Canto Evo 2 mk.2 monoblocks driven by a VTL 6.5 in balanced mode. . . and the combination was quite delicious, while exhibiting no audible problems.

NuForce Sig V9 SE monos worked very well with my ARC Ref 3 in balanced mode. . . large sound stage, excellent imaging and extension. . . very graceful really!

I have also driven a Rowland 312 digital amp in balanced mode with an Audio Research Ref 3, and the result was excellent.

Just one recommendation. . . as digital (or switching) amps are usually true balanced designs, it may be advisable to drive them with balanced line stages to maximize results.

To a great extent, component compatibility is unpredictable, and the only way to really know is to actually try different combinations. However, as a general rule, I have found that the idea of mixing and matching so that the strengths and weaknesses of one are "balanced" by contervailing strengths and weaknesses of another hardly ever works out; one tends to lose the good qualities of each as a result rather than attaining balance.

I have tried solid state linestages with tube amps, as well as the other way around, and while some mixes worked out reasonably well, for me all tube worked the best. Some of the worst combinations I tried were tube linestages feeding solid state.

I've only heard the Bel Canto Class D amp and a very expensive Rowland (@ $14k). A bunch of friends had fun trying the Rowland in their systems. The Rowland worked best in a system where it was fed by a balanced Hovland preamp. While "not bad" in this system, it did not sound great either. The top end seemed shut down and microdynamics were slightly blunted.

In the other friend's system, which is a very sensitive and very picky custom horn system (fed by a custom tube linestage), the Rowland sounded much worse. It had an odd, unnatural sound that I could not exactly place what was wrong (not an obvious tonal problem). Again, the top end was almost completely missing, but, more troubling was a loss of the sense of notes naturally blooming into space and decaying naturally. Musically, the system lacked "soul" and sounded lifeless compared to what it sounded like with very small triode amps. It may be the case that the amp would be at its best delivering much more power as these speakers require very little power (they are about 106 db/w efficient).

Both of these systems have been carefully constructed over the course of many years, so a quick drop-in test hardly says anything about the inherent qualities of the Rowland amp. But, it does demonstrate that they are hardly the panacea for any ALL systems.
Hi Larryi, JRDG has made many amps in the course of their history. Which model did you listen to? 1, 201, 9, 3, 5, 112, 301, 7, 302, 7M, 6, 8, 312, 12, 501, 8HC, 9T, 102, and a few more? Some are switching amps, and some are not, some have been great sounding, while some have been just great experiments.
A fantastic, yet simple, system employing class D is a PS Audio GCC 100/250 or 500. Great value and outstanding sound when combined with the right cables. My favorite speaker cable is Clear Day solid Core Shotgun or Double Shotgun. DS is clearly better but almost twice the price. My CD player is a Raysonic 168. Speaker choices will depends on how much space you have, whether that space is dedicated to audio or shared and what type of music you listen to.
07-24-08: Guidocorona asked:
"Hi Dave, did you mean Spectron digital amps rather than Spectral? Spectron Mus 3 is a fabulous switching amp!"

Sorry, yes I meant Spectron.

I have a Supratek Sauvignon using balanced IC's into a Spectron M3 SE and the combination is wonderful.

Your words are exactly what I'm hearing, also I'll add quiet,extended,smooth,transparent,dynamic,and finesse.
"I have a Supratek Sauvignon using balanced IC's into a Spectron M3 SE and the combination is wonderful."

And there you have it guys. . . all great switching amps driven by great tube pres. . . spectron, Rowland, NuForce, Bel Canto. . . and they will work just fine together!
DynaPAS(all upgraded) with a hypex UcD400 power amp. Sounds
Guidocorona, you left out the Gilmore from your list. In my evaluation, the Gilmore blew the NuForce Ref 9 SE V2 completely and utterly out of the water. I'm sure it was just an oversight...
Hi Ait, unfortunately I have no experience with amp2amp warfare. . . . and I have not yet heard the Gilmore. Do you know if it will be featured at RMAF?
But on this particular thread we are not contrasting digital amps, rather we are enumerating combinations of switching amps and tube pres that we have personally enjoyed and found to be working well. Have you driven the Gilmore with a tube pre? G.
Hi Guidocorona,

It was one of the earlier Class D amps, though I don't recall the model number. I bet it was still low on the learning curve and subsequent models have been improved.

I am hesitant to talk about "tube magic," because it means different things to different people, and because MOST tube gear I hear completely lack what I look for in tube gear (particularly, high-powered pentode amps driven by KT-88/6550s disappoint). In my setup, I did not fully get what I was looking for until I found a suitable tube linestage and a tube phonostage to match with my parallel single ended triode amp. The Levinson No. 32, which I still keep as a backup, did not quite deliver what my Emotive Audio Epifania delivers.

I am not saying that tubes are superior. In systems where more power is needed, I think that solid state is often much more desirable than high-powered tubes -- different horses for different course. I bet Class D would be the appropriate choice in some applications. The point is, one cannot make a generic choice, trial is the only reliable method. Also, I think one will usually not find success trying to compensate for strengths and weaknesses based on perceived individual qualities of particular components; the results are too haphazard for that.

There is a lot of practical sense in sticking with one brand for amplification or to go with an integrated -- usually, a good designer has worked out such compatibility issues.
Hi Larry, do you happen to remember if the JRDG device in question was a stereo or mono amp? and if mono pair. . . whaht physical size/weight?
Hi Guidocorona,

It was a massive, single chassis stereo amp. I think the model number was 302, but, I am not sure. The owner used it to power Kharma speakers, but sold it in favor of a Hovland amp after buying a pair of Sonus Faber Anniversarios. We got to play with it prior to it being shipped to a buyer in the far east.
Hi Larry, yes the device was very likely a 302. I have heard it a couple of times, driven by an aRC Ref 3 in both occasions. 302 was JRDG 1st gen switching amp with internal PFC. . . not bad for a first attempt, but I also observed some of the problems you found: only very moderate macro and micro dynamics, and a treble that was not too extended. These problems are solved completely by its successor--the current 312 model. Conversely, a clearly anomalous/strange sound in the treble region was probably caused by insufficient breakin or warm up. Switching amps seem to be total bears and may require well over 1000 hrs of playtime to break in. . . or at least the JRDG 312 and NuForce V9SE definitely do. The symptom seemed to me of a treble that sounds almost harmonically disjointed from the rest of the audible spectrum, and disconcertingly displeasing to boot. . . but the issue goes away completely with proper break in and warm up. . . it's just an unusual temporary artifact of these devices.
Guido and I tend to agree, but I must report that my Continuum 500 seemed fully burned-in by 200-hours. Jeff is constantly improving, so maybe his latest capacitors or something else changed the burn-in characteristic.

Others I trust report 500+ hours for 501s and 201s, so I don't think that Guido is "hearing things" that don't exist. Instead, I think that the landscape is changing very quickly and Rowland evidently hit on several ways to advance his pre and power amps very recently.

Hi Dave, the different and hotter running PFC circuit in the new Continuum 500 integrated may account for shorter break in time than on 300 series stereos, as well as JRDG monos without PFC like 201 and 501. In general, I prefer to be conservative when it comes to break in times. . . too many folks give up on a device prematurely because of their impatience with break in. G.
I suspect you're right Guido, or it could be the new capcitors.

Anyone got a Continuum 250 (without PFC) and would they share their burn-in experience???

Jaffa_777 No problems here with my class D tubed pre combo. The addition of my tubed preamp was a step in a better direction for my class D amps and system. A warmer presentation indeed.
Stltrains, what is your amp+pre combo exactly? Guido
Im using a deHavilland Mercury II preamp with the NuForce 9.02 SE V2 amps in single ended mode with stunning results
Yoby, you hit on a great combination. A sweet tubed pre-amp with a SOTA class D. I ended up with my Modwright while looking for a deHavilland. Funny thing, nobody wanted to sell theirs! Still, I love my rig. I wish I could hear everyone else's rig. Wait, maybe not, I would just spend more money!
I have a Supratek Chenin tube preamp usually paired with a Bryston 4BSST driving a pair of Dynaudio Confidence C1 in a 5x4 m room. I just picked up a pair of used but fairly new Bel Canto Ref 1000 monoblocks 2 days ago and was all excited about trialling my first class D amp after reading all the rave reviews, especially 6moons.

Well after 3 days, i'm disappointed and perplexed. Adding the BC Ref 1000 has sucked the life and excitement out of my system. The high sounds rolled off to me,lacking air and i struggle to hear the attack/leading edge of piano strokes during Solo piano recording. Soundstage depth is so so and everything sounds a bit homogenised.

My personal taste is for a bit of warmth and bloom in mid range as a neutral system will grate my ears after a short while. I'm aware of the tubey warmth some reviewer has elluded in the reviews but this is too much. So far it's no high end bargain.

I don't know how many hours they had before i got them and wonder if burning in will help. I left them powered on as suggested but the sound is still lacklustre so far. Gr.....
Well, three days isn't enough burn-in, but if you like extra midrange bloom, then Bel Canto is probably not for you. Rowland will not work for you either. You'll need excellent sources with most Class D/ICEPower amps.

Bel Canto are never bloomy Jaspert. But your BCs are likely needing several hundreds hrs of real playing time (probably 500 to 1000) before stabilizing. . . . Turn on the tuner and let the creatures make music for a spell. . . and it may very well be that in the end you will still not enjoy them, or you may find Nirvana instead. Also consider that switching amps like better to be used in a balanced configuration. One last issue is impedance matching between your Chenon and the BC. What's the output impedance of the pre and input impedance of BC? g
Guido, sorry to hijack the thread a bit, since you asking, may I know what is a good matching impedance? Does it mean an equal value of them or there is a factor?
forget to mention, mine is 400ohm output from pre, 25k ohm input on amp, does it mean very bad matching?
Grandetech, from an impedance match you should be fine. Your ratio is 25000 / 400 = 62.5. I suspect that anything greater than a ratio of 25 is above the 'waterline'. G.
I'm not after more mid range warmth/bloom from the new Bel Canto as the existing setup (not from the Bryston 4BSST) has a bit of that compared to other systems i've heard. I was hoping for more resolution and more dynamic sound from the new pairing.

In terms of impedance matching, i think the Supratek Chenin has about 600 ohm output impedance and the balance inputs on the Bel Canto are 20 ohm. Surprisingly, i have to dial up a bit more volume control to make the sound come alive when compared to the 300W/500W 8/4ohm Bryston.

I've asked the seller for their background and he stated they have about 150~ 200 hours playing time so i will give them more time to burn in and report back later if there's joy to be had.
Jaspert, with 150 to 200 hrs on them, the Bel Canto are likely not even a quarter broken in. If at about 1,000 hrs of making real music -- not idle time -- they are still not of your liking, it may be time to move on. Do keep us posted.
Has anybody tried the Red Dragon Leviathans?
I saw a set in the classifieds and checked out the reviews I could find online. All good reviews. I have magnepans and a tube Rogue Perseus Pre. Using a Rotel SS right now.
Heard Red Dragon monos. Very dynamic but far too dark sounding for my particular taste. Guido
Since this topic is being discussed any thoughts on THE tube preamp to go with the new Spectron Musician III Signature Edition MKII. Budget in the $7-8K range or less, of course. HT bypass would be nice but seems like most companies are adding that option now. thanks
The Red Wine Audio Isabella (with built-in dac) battery powered tube preamp + Red Wine Audio battery powered Signature 30.2 amp - as long as you do not need a ton of power and it is in your budget, you will be seduced by the sound! I own this pairing and cannot recomend it highly enough!

Hi Bostonbean, with an input impedance of 50K Ohms on both RCA and XLR connectors, the Spectron Mus 3 Sig II should be quite easy to interface with almost any tube pre. My current favorite tubed line stages are the ARC Ref 3 and the VTL 6.5, but I have not tried them with the Spectron.
What, no class D bashing? Have we finally arrived?

IMO Jwarmbrand's suggestion is more to the point. With class D the question isn't so much tube or solid state it's getting as much off the grid as possible. My Nuforce SE's took on a much fuller and more quiet presentation when I replaced an upgraded A I 3A with my current battery powered pre.

Unfortunately the resolution and transparency offered by many class D designs is often misdiagnosed as sterile or forward. My system benefited greatly from a new metal clad conduit, dedicated AC line, and from mass loading the SE's casework with some DIY sandbags. Addressing the vibration and the AC should be seriously considered before applying the tube preamp band aid.

All my vacuum tubes have now migrated from the back end to the front. The output section of my ModWright/Denon player is tube driven as is my FM tuner. There is no substitution for the effect tubes can have on an audio system and I haven't heard any solid state or class D product that sounds like tubes. Likewise, I haven't heard a tube system that sounds like a well executed class D system.

I have heard noise at low listening levels from the four tube preamps I auditioned in my system. Not that big of a deal and the noise wasn't an issue at louder levels. I think there is a battery powered tube preamp, Dodd?
"What, no class D bashing? Have we finally arrived?"

Vicdamone, I've been there for a spell. . . as far as I am concerned class D is one more perfectly legitimate amplification technology, like everything else replete with the bad, the good. . . and the ugly. G.
"Addressing the vibration and the AC should be seriously considered before applying the tube preamp band aid"

Vicdamone i concur big time with your statement above. I'm not using sandbags but i am addressing vibrations also as well as AC and the improvements are very audible for sure.

Any one who bashes any gear is a fool. There is enough equipment out there for all to find enjoyment and as we all hear differently who cares what type of gear blows your skirt up. We are all in this for musical enjoyment i suspect and the way you get it done is your musical happiness business. I"ve had some interesting volleys with some bashers in the past dealing with gear. Hell its your ears and money listen to what pleases you.
Stltrains, Hear, hear and nice looking system you have.
After my earlier concern expressed in the earlier post on 26/7/08 , I continue to log long hours with Supratek Chenin tube pre + Bel Canto Ref 1000 combintion. After 2 weeks,the ICE power amp sound has changed quite a lot.
I was initially told they've about 200 hours on them but the seller later said they would be lucky to have 50 hours playing time before i got them. Hmmm..
I later emailed Mick Maloney and he clarified that Chenin output impedance is actully 200 ohm , not 600 ohm i stated earlier and with the 20 kohm balance input impedance of the BC Ref 1000 matching should not be an issue.

As for the sound, the veiled, congested and rolled off sound i heard a few weeks ago has definitely disappeared. The top end has more sparkle and instrument separation is better now. These changes are not that subtle to my ears. I could hear some graininess in the HF region from a few recordings again and i certainly hope this won't get more pronouced as i can't stand sibilant sound. It's not all rosy though as another impression i get is the bass is just a bit plodding and PRAT could be better relative to my old amp. Over the two and half week period, i did put my Bryston 4BSST back in 3 times just to compare and confirm my impression.

I think burn in is definitely real with these ICE power amplifier.I was all ready to sell them 2 weeks ago but now i think they could be long term keeper. May be..

Hi Jaspert, there are only 3 things that matter when inserting switching amps in a system: patience, patience, and more patience. Once you have logged a little over 1000 hrs of playing time on them, the BC will probably be starting to give you their best. . . and at that time you'll know if they are truly for you or not. G.
There are a lot of wizened people contributing to this topic. Several are mirroring my experience over the four years I went class D over conventional amps. What I thought was really cool then would be nonsense to my ears now. With the narrowing down the components that do work, and those that don't my sound has taken leaps to ever more accurate fidelity. Like Guidocorona says, Patience is needed.

Oh, on topic, I am using a class A preamp of unearthly quality. The tubes are in the non-oversampling DAC.
Bostonbean thanks for the kind words on my system i've put in alot of time and effort to get the sound i am receiving now which is to my ears is superior. Imaging, sound stage, bottom end and air along with a super 3 D delivery. Along with many different components going in and out of the system the wife and myself have logged many hours enjoying music with it.

Muralman1 i have gone the upgrade route with my amps two offered in the past 3 years. One of the best moves in the right direction was going with a tubed preamp with Siemens cca tubes using my class D amps. I also think that my preference to analog playback with vinyl adds to what my amps and system can deliver. A very easy to sit and listen sound.
Yours is a great system, Stltrains. Your sound is, "Very easy to sit and listen to." My sound leans more to the live band. That is what I prefer. That is the marvelous thing about class D. It's sound can be sculpted to any preference.
Muralman1 aint it just grand when we get our system to sound the way we wanted it to. As you already know it takes a lot of time and effort to get the best from your system, sitting pat wont do. You can get the sound you thought was possible. Glad you have yours sounding the way you hoped.
Enjoy the music.

I think you need to mention that your assessment of the Gilmore amp as compared to the Nuforce was based on experience w/ your particular system where the Nuforce Ref 9SE V2 had issue with noise. I mentioned before that the Nuforce once properly set up, will shine like no others but only IF properly set up. Now, the top of the line Gilmore is based on the ICE power ISP 1000 module of which I have experienced in my previous amps, the Bel Canto 1000. The comparison wasn't even close, the Nuforce was head and shoulder above the Bel Canto (SOLD) and I would think the Gilmore could not be be much different.

Just my $.02.

Hi Kenk168, I have never experienced noise with the excellent Nuforce Ref 9SE V2. under what circumstances may such noise show up and become a problem?