[WEEZ]

Frank, the $1500 price point (give or take) should make for a popular product, I would think. Having all the jacks and cords coming out the back is a definate plus. Some thoughts:

1) Keep ALL the tubes up on top,
2) Forget about transformer covers & cages,
3) Consider only 4 & 8 ohm taps if you source transformers from scratch- should be less expensive?- plus a 16 ohm speaker is rare today...*
4) Put the new plain faceplate on the front- so it matches your pre-amps!

I can see it now.. an all black AVA 'Stealth Ulimate 70'.

 

WEEZ

*there are two manufacturers that offer only one tap: 5 ohm. They used to be ralated to each other- now separate companies. I'm sure you know who they are. The claim is, that 5 ohms is 'within a stones throw' of working with most modern speakers. Could be bunk.....?

[guest1632]

If you guys could just hear an Ultra DAC driving an Ultra SL preamp driving an Ultra Phase Inverter driving a pair of Ultimate 70 tube amplifiers, the debate you raise would be over, no contest.  We will make your digital amplifiers sound just icky.

And it is so nice in keeping the sound room warm on a cold winter day.  :)

Frank Van Alstine

Hi Frank, Well, you might have a poinbt there, ... but! the stereo 70, if I understand is not available except for those who have upgrades to be done. Also, the energy used to produce that warmth well, that is wasteful.

It would seem that you have one of the best hybrids out there now. It does seem to me that for example an investigation with the UCD modules would be in order. I remember when the CDPlayers were first out there on the market. Yep! they were bad, no question. They have come a long way. Give the digital formats to settle down, and we shall see. The UCD modules are one of the best "digital" modules out there at this time for high wattage. Remember when the transistor came out. This could never be a uasable audio ampifier.  

Ray

[Feanor]

...
Bottom line? An interesting exercise but disappointing results. The SAXR45 - despite i ...

I own a Panasonic SA-XR25 digital as well as a Bel Canto eVo2i.  I agree that the Panasonics, (based on the XR25), don't quite live up to the hype they got a few months ago.  The Bel does soundly beat the Panny in all respects, though both are based on Tripath technology, so I'm told.

[Feanor]

We are thinking about it and have done some price studies already.

It would be essentially an even better version of the Ultimate 70 in a much modernized chassis. The input jacks would move to the back, the power switch to the front. The outputs would provide for all for transformer impedances (4,8,16, and G), black powercoat finish. The chassis design would provide for the audio borad to be mounted under the chassis (parts down) with only the 6GH8A tubes sticking up thru appropriate circular holes in the chassis. There would be simple pin jacks provided for bias setting rather than the 8-pin sockets used now. There would not be a cover cage as the new board location isolates the high voltage stuff.

Layout suggestions and feature and function suggestions are welcomed.

...
Price, I guess about $1500 for a finished little state of the art amp at 32 watts per channel. Using two of them in the bridge mode with our new Ultra bridge provides drop dead musical performance and adequate power for most anything. You gotta hear it to beleve it. ...

Oh, weary whoa!  Another 30 watt tube amp.  Pretty glowing tubes on top, etc..  Do we really need it?  No exactly original, though I'm sure Frank would do a fine job.

For me this brings things full circle.  Viz., my original suggestion:  what I want is a tube/switching hybrid.  Tubes doing what they do best which, if I'm not mistaken, is handling voltage gain.

[avahifi]

Ahhum, the circuit design IS original and don't blow it off until you have heard it.

Switching amps, all that I have heard, come to my shop with great expectations, measure with a big band of wide range "fuzz" on the top of the scope trace, and sound like reheated frozen Budget Gormet dinners.

Nasty is all I can say so far.

[guest1632]

Ahhum, the circuit design IS original and don't blow it off until you have heard it.

Switching amps, all that I have heard, come to my shop with great expectations, measure with a big band of wide range "fuzz" on the top of the scope trace, and sound like reheated frozen Budget Gormet dinners.

Nasty is all I can say so far.

Hi Frank, That's sure funny, reheated frozen dinners.  Seriously though, have you seen any of the UCD designs?

Ray

[skrivis]

Ahhum, the circuit design IS original and don't blow it off until you have heard it.

Switching amps, all that I have heard, come to my shop with great expectations, measure with a big band of wide range "fuzz" on the top of the scope trace, and sound like reheated frozen Budget Gormet dinners.

Nasty is all I can say so far.

Hi Frank, That's sure funny, reheated frozen dinners.  Seriously though, have you seen any of the UCD designs?

Ray

There's a good article at: http://sound.westhost.com/articles/pwm.htm

It points out that the main benefit is efficiency, which is really a way of saying the cost is less. It _does not_ claim that Class D amps are the best thing since sliced bread and everyone should switch right over to them.

There's also a section where it becomes obvious why nobody is using tubes for these amps - they're too big.

[JLM]

Having been serious about audio since the 70's I've heard tubes, SETs, chips, and lots of solid state.  Unfortunately I've never heard a AVA product, but have respected Frank's values and experience.

The early digital stuff was a bit of a joke (like first attempts in many other technologies), but amazing for what they were (like the Sonic Impact).  The JVC and Pannasonic receivers are cheaply built, but again offered obvious sonic advantages at their price range.  Many have seen the promise.  

Admittedly we're still in the infancy of digital amp development, but several serious products are already out there.  Just at AC we have Bolder, Channel Islands Audio, NuForce, and Red Wine Audio selling digital amps.  I listened extensively to a couple of digitals, one of which I bought from here (AC).  I consider it the best sounding amp I've ever owned or heard in my home.  

Like Feanor, I am interested in adding a tube pre-amp based on reports of the synergy provided.  Yes, this is Franks Circle and he can say what he wants, but I must say that his position on digital is most disappointing.

[skrivis]

Oh, weary whoa!  Another 30 watt tube amp.  Pretty glowing tubes on top, etc..  Do we really need it?  No exactly original, though I'm sure Frank would do a fine job.

"There's nothing new under the sun."

Class D amps aren't very original either. They've been around for a while. There are also a bunch of them around right now, so how original would it be to design yet another one? "Yawn, another Class D amp. Oh, weary whoa."

The new AVA tube amp would provide a brand new (not dependent upon the supply of Dyna ST-70 amps) amp, with sufficient power for many, if not most uses - plus it's an amp that's done right. How is that not original?

For me this brings things full circle.  Viz., my original suggestion:  what I want is a tube/switching hybrid.  Tubes doing what they do best which, if I'm not mistaken, is handling voltage gain.

Ok, but I would ask why you want this. What benefit would there be over AVA's current products? AVA's current products are priced reasonably, so I don't think a Class D amp would improve prices. The current models may run a bit warmer and weigh more than a possible Class D amp, but is that really a concern? I could understand size being an issue for HT use, but that isn't a concern for everyone.

Weight? I don't carry my amps around that much.

Heat? That also isn't a major problem for me.

[avahifi]

OK what is the best off the shelf digital amplifier around right now?  Tell me what to get and I will give them another listen. Web link appreciated.

I am not interested in after market modified units, just what the original vendor can do.

Frank Van Alstine

[skrivis]

OK what is the best off the shelf digital amplifier around right now?  Tell me what to get and I will give them another listen. Web link appreciated.

I am not interested in after market modified units, just what the original vendor can do.

Frank Van Alstine

The article I mentioned above was written by one of the people at ColdAmp. http://www.coldamp.com

UcD is from Philips, and one of their engineers has an article here: http://www.audioholics.com/techtips/audioprinciples/amplifiers/classDamplifiers.php

NuForce might be worth a listen. http://www.nuforce.com/

A UcD or ColdAmp module might be a good place to start. I suspect you have plenty of pieces parts already so you can build an amp around the modules.

The tech info I've seen on Tripath didn't really impress me. They seem best suited for "lifestyle" products like Bose et al. ARC uses them though, and they're local...

[JLM]

Another suggestion for a good digital amp is the D-200 monoblocks from Dusty Vawter at Channel Island Audio:

http://www.ciaudio.com/

I believe that they too use the UcD module, but with additional enhancements.

[modular747]

OK what is the best off the shelf digital amplifier around right now?  
Frank Van Alstine

Halcro makes some expensive multi-channel (2-7) class D amps which they claim use "distortion cancelling" circiuts:
http://www.halcro.com/logic/productsMC20.asp

They aslo make even more expensive "ultra low distortion" non-digital units for their "Reference" audio line which use unigue designs.

BTW, is class D output topology really "digital"?  Pulse width modulation is really an analogue signal which requires a steep L-C low pass filter at the output to remove the ultrsonic garbage. Also, it produces a large amount of inherent (i.e. unrelated to the nonlinearities if the solid state devices) frequency related distortion.  The only advantage of class D I know of is that it's a lot more electrically efficient and produces a lot less heat than "convetional" class A, AB, or B topology.

[guest1632]

OK what is the best off the shelf digital amplifier around right now?  Tell me what to get and I will give them another listen. Web link appreciated.

I am not interested in after market modified units, just what the original vendor can do.

Frank Van Alstine

Hi Frank,

Well, all I can do here is read all of the various reviews pros and cons. It appears for the high powered stuff the UCDE stuff seems to be the best for stability, safety, and low noise issues. The ICE and Nuforce stuff have safety issues, and stability issues. You can get them from Kevin over at DIYcables, and his circle. I have never said these are the cat's meow. The tripath stuff, have noise issues. I first heard of your stuff back in the early 80's. You can buy the modules from Kevin, and you probably have all of the stuff to coble together a decent supply. The UCD180's use a 300 VA transformer and the UCD400 uses a 500 or 600VA transformer. Kevin can give you all the particulars. I will be most and I do mean that most interested in what you find.  

Ray

[guest1632]

Another suggestion for a good digital amp is the D-200 monoblocks from Dusty Vawter at Channel Island Audio:

http://www.ciaudio.com/

I believe that they too use the UcD module, but with additional enhancements.

Remember, he was asking for off the shelf. Dusty does use the UCD modules, and modifies the hell out of the modules. They are no longer off the shelf products.

Ray