845s: To biamp or not

Hi Paulfolbrecht

I bought a pair of Hyperion 938 speakers recently. I am considering 845 tube amps to drive it. Looking at several options:
- Hyperion's own HT-845
- Consonance Cyber 845
- Antique Sound Lab 1009 (dual 845)
- exploring others...

How would you describe the sound of the Consonance compared with other 845 amps?

Paul, when I blew one of my Cyber 211s with a bad NOS tube, I approached the U.S. distributor to get a schematic. He said none was available. I sent them to a close friend who modifies gear for repair. Given what you were told by them, I am glad I did not trust them to repair the amp.

I had not thought of trying the 6900 tube and will probably not try it now. I am not sure that having 6900s does not violate your concern whether NOS are worth the cost.

Ethifi, I bought the 211 version of the Consonance Cyber series largely on the strenght of the Enjoythemusic review and a pair being available on Audiogon. I had also heard very favorable things about these amps. I needed greater power than the present 8 watts that I had.

Since getting the amps, I have greatly improved them by using better tubes, carefully isolating the amps on good stands, changing the fuses to IsoCleans, and putting them on ac filtering. I doubt if brand to brand variations are as great as these changes. Also the guy who repaired my amp says he thought they sounded excellent and used very good parts.

How do the prices of the amps you are thinking about compare?

Jsadurni - That Dared ought to be PLENTY of power for 94dB speakers if that is accurate and if they do not have really nasty impedance & phase swings. I had that same amp and it drove 88dB Gallos very well indeed. If it wasn't so huge and ran so hot I would have kept it.

Ethifi - The Consonance amps are 1st rate in every way. Build quality, parts, sonics all top-notch. American stuff like this would cost $10K.

The new Hyperion 845s, however, may turn out to be killer as well.

ASL - you can read all day about them. Good sonics, good deal, for sure, but more than a few have had issues with the gear.

My experience with this 8w Dared amp is steering me well away from bi-amping. If this tiny 8W amp can produce GOOD bass in these speakers, the 845s sure can (I knew that). Well, I mean, I have played with the Gallo amp some more, and while it does tighten up the bass some it is not worth the hassle and extra load on the source. I will try it again with the 845s when I can but when in doubt, go for simplicity, I say.

Paul, I would agree that an American counterpart to the Cybers would cost at least twice as much, but the parts, build quality, and basic circuit show shortcuts to allow the low price. I do like the sonics, however.

The power supply is very simple and limited. It is probably why you had your failure with an output tube that drew more current.

I suspect that there would be only minor variations among 845 amps, with the wiring, output caps, and ac filtering. Better of everything including tubes will improve the sound. The question is what you are willing to add to your basic model.

Tbg, I'm very curious to hear specific shortcuts in parts or "circuit" that you see in the Cybers. The parts are all just about top-tier, if not top-tier. Ditto on the build quality. They are put together very well and the enclosures are faar from simple - the amps could be much cheaper if they were in basic boxes, I am sure.

I may agree with you about the power supply - but, with a Class A design, when you are at 100% power all the time, why build a power supply that can supply substantially more than will ever be drawn? More than the tubes they planned for could ever draw, that is. I certainly agree that it is a least a weak point that they don't allow these higher-current tubes to be used.

Maybe they didn't think of it or want to deal with the issue or maybe it was a conscious decision. Some elements of the amps - like the 5687 drivers which are not common at all, and the designers explanation for their choice - have lead me to believe that a lot of thought did go into these amps.

The fact that they are as quiet as they are also makes me think this isn't simple, basic stuff. It is not easy to make 845 amps as quiet as these are.