[avahifi]

We are considering tooling a new chassis for our Ultimate 70 Vacuum Tube Amplfier so that it can be produced without needing an original Dyan St-70 chassis.  It would be available both factory wired and in do it yourself kit form.

We would like your comments and suggestions for it's design.

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? A lot depends upon the transformers. The Triode Dynaclone transformers work really well, especially the power transformer and choke. We might want to go with an even better output transformer from Magnaquests, and that would raise the price.

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.

Frank Van Alstine

[ScottMayo]

There would not be a cover cage as the new board location isolates the high voltage stuff.

If I ever decide to take the dive into tubes, this might be the direction I'd want to try. But let me recommend you sell an optional cage. One thing that keeps me away from tubes is RF interference from other devices getting into the tubes; the other is the thought of children or pets getting personally involved with the pretty glowing glass.

[modular747]

We are considering tooling a new chassis for our Ultimate 70 Vacuum Tube Amplfier so that it can be produced without needing an original Dyan St-70 chassis.  
We would like your comments and suggestions for it's design.

2, 4 & 8 ohm outputs (16 ohm not too useful).  Optional Ultra 70 bridge board internally with switcheable bridging.  Meter or LED's for easy output tube bias adjustment.

[Bill Baker]

Sorry. I don't normally post on another manufacturer's forum unless asked to or have a particular interest but I have been following this one and wanted to give my 2 cents.

 

I'd be a tad concerned about up and coming low-cost competition from the Chinese long term. Not only do they make entry-level tube amps now, but if history is any guide, they wouldn't hesitate to "borrow" your design if it turned out to be popular. However.....

 While the Chinese are now making some decent designs, I still feel they are far from being superior. As far as copying designs, I have seen them do this in some situations but trying to copy or equal the status of AVA products??? I don't think they have it in them.

Functionally, I'd want 3 and 6 ohm speakers taps. Nothing else is really needed. Forget 16. I like the idea of a built-in meter, lettered in a 1930's-50's font or in a high tech LED as 747 said.

 Myself, I wouldn't mind seeing 16 ohm taps on more tube amplifiers just as I wouldn't mind seeing more speakers rated at a higher impedance to pair with tube amps.
.

As far as what you might style for, I like what you've come up with except perhaps the black powder coated chassis. The 'black' look shows dust easily and is over 20 years old. Instead of just black, why not offer powder coating in a choice of two or three colors? Maybe a beige/gold like those gorgeous early Marantz tube amps, and an electric blue (my fave).

 I like your ideas of the nostalgic beige/gold combination but still a fan of that ol' black chassis. Power coating is one of the most durable finishes available for chassis finishing and i think this is a very good idea.

Concerning tubes, be sure to have the them in front and on top. They should be visible from above, below and at eye level. And you're right, no cage to block the view.  

 Amen to to that.

The more you can make the amp look like a piece of art and less like an industrial lump of metal the better, as long as it's on the cheap.

 "On the cheap" is very subjective so I won't go down that road. I think a better way of putting it is as an "exceptional value". Looks do play a large roll with some with performace being the main factor. Looks are also very subjective as everyone has their own taste on what "looks good" to them.

 As long as it has glowing glass and performs nicely, I'm happy.

[avahifi]

One thing to keep in mind, you can successfully use a 32 watt very good vacuum tube amplifier where you would normally use a 100 watt solid state amplifier.  Heck if I know why.  But one of them drives a set of B&W 802 Series II speakers quiet well indeed and those speakers were the downfall of lots of 200 watt per channel solid state designs.  A pair of Ultimate 70 amps bridged into the 801s is more spectacular than you would ever believe.

Frank Van Alstine

[WEEZ]

(in addition to my comments in the hybrid-class D thread, I would offer the following..)

Most of the Chinese amplifiers hitting the market are control amplifiers with a selector switch and volume pot. For someone curious about tubes, one would have to admit that the price point is attractive (the Jolida 302 being a prime example). Bill Baker has taken the Jolida amps to great levels, it seems.

Rogue has introduced the Titan series, and the Cronus is a control amp with a built in phono stage (ss); a tape-out; a sub-out; and (3) line inputs, volume control and balance control for around $1800. Lots of value there.

The Ultimate 70 has (2) stages of amplification, and would need a pre-amp (active or passive) to compete with the control amps out there...

So, IMHO, depending on where AVA wishes to compete- above the $1500 price point would take convincing the market that having to buy a pre-amp is 'worth it'. (Quicksilver Mini-Monos still sell for $998/pair with 25 watts each but require a pre-amp).

(by the way, I still don't believe the claims of 50wpc from an El-34 based amp like Jolida claims w/ the 302; but it doesn't matter- tubed amplifiers sound louder than solid state amps with similar power, as Frank pointed out. I've played my 87db/w/m Merlins to ear bleed levels with 25wpc of tubed power. Probably it's the 'softer' clipping and the fact that most tubed amps have more benign distortion, so they just sound 'big')...

I wish AVA the best of success if the project goes forward.

One final thought- what would be the trade-off in power and/or sound quality to eliminate the manual bias altogether and make it cathode bias- or 'self-biasing'?

WEEZ!

[WEEZ]

..then again, if the sound quality is REALLY good- the competition jumps to the $3000 and up price point, so maybe there's room above the said $1500 target....

hmm  

WEEZ!

[skrivis]

(by the way, I still don't believe the claims of 50wpc from an El-34 based amp like Jolida claims w/ the 302; but it doesn't matter- tubed amplifiers sound louder than solid state amps with similar power, as Frank pointed out. I've played my 87db/w/m Merlins to ear bleed levels with 25wpc of tubed power. Probably it's the 'softer' clipping and the fact that most tubed amps have more benign distortion, so they just sound 'big')...

Musical instrument amps usually claim 50W out of a PP pair of EL34s (or 6L6s or even 6550s). I guess Jolida is saying that their amp is really a guitar amp....

[skrivis]

One thing to keep in mind, you can successfully use a 32 watt very good vacuum tube amplifier where you would normally use a 100 watt solid state amplifier.  Heck if I know why.  

By "solid state amplifier," do you also mean your hybrid amps with SS output stages?

[WEEZ]

skrivis,

the Jolida amps may not be in the league with Joule Electra- but I doubt they use design criteria from guitar amps.....

the 50w rating must be peak power though. There are other hi-fi amps claiming 50w from a pair of EL-34's too, but that's likely a stretch...

WEEZ

[avahifi]

Of course not.  

[guest1632]

We are considering tooling a new chassis for our Ultimate 70 Vacuum Tube Amplfier so that it can be produced without needing an original Dyan St-70 chassis.  It would be available both factory wired and in do it yourself kit form.

We would like your comments and suggestions for it's design.

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.

Hi Frank, Well if you do build a Stereo 7p, you might consider putting the inberter in the unit.

Ray

[MarkM]

I like the idea of offering it in kit form.   Looks like you are making sensible changes that are appropriate.   No bias meters, black powder coated chasis is fine, $$$ I don't mind pulling out the meter once in a while to bias the amp.  

I want one in kit form.  Let me know when you are taking orders.

[skrivis]

skrivis,

the Jolida amps may not be in the league with Joule Electra- but I doubt they use design criteria from guitar amps.....

the 50w rating must be peak power though. There are other hi-fi amps claiming 50w from a pair of EL-34's too, but that's likely a stretch...

WEEZ

Historically, there hasn't been much difference between power amps in musical instrument amps and other power amps for audio use. One guitar amp, the Fender Twin, runs the power section in Ultralinear.

Mesa Engineering makes some amps that will work for multiple uses. Bass and keyboard amps, as well as home or studio stereo use.

There have been some unusual designs in power amps for guitar use, starting in the late '60s or so, but it's normally the preamp section that suits an amp for guitar.

I have no idea what criteria Jolida uses to design their amps, but their 50W rating suggests that they're _not_ designing a hi-fi amp.

[WEEZ]

Frank wrote: "Of course not    ". In response to what?, I wonder...

skrivis,

Not much difference in guitar amps and hi-fi amps? What?  

Back on topic; my vote goes for everything Frank talks about as far as re-locating the jacks and cords to the back; a powder coated chassis; and concealing the curcuit board.

Again, I would add the new faceplate on the front (so it matches other AVA gear) - will it fit? And keep all the tubes up on top, so tube rollers can plug and un-plug 'till their heart's content.  

As far as a cage, well.., maybe optional. I love kids and dogs. Now cats.., well.., I'll stop here..

Colors? black or pale gold...

over and out,

WEEZ

[avahifi]

The "of course not" was in response to assuming that one of our high powered Fet Valve hybrid amplifiers fell in the class of 100 watt solid state amps the Ultimate 70 can equal in performance.  The answer is "no way".  The Fet Valve Ultra amps win hands down unless you use a pair of Ultimate 70s and the Ultra Bridge, then its really really close.

Dogs, cats, kids and vacuum tube burns.  I checked with other vacuum tube amp manufacturers and asked if they ever had any feedback on anyone being burned by their equipment with no cover cage and the answers came back "no problem".  I have cats myself, Oliver and Stanley, two 5 year old really gentle grey stripped tabbies, and they are smart enough to avoid glowing vacuum tubes.  I assume parents will be smart enought to keep the equipment out of young children's reach.  As for dogs, well I don't know if they are smart enough to avoid fried noises and paws.  I hope so, but will not be held responsible for dog stupidity.

So there.

Frank

P.S.  Thanks for all the comments.  Design work on the chassis will start in a couple of weeks.  It will look nice, be priced as reasonable as possible (I am not going to work for 40 cents an hour so buy Chinese if you must, just don't cry to me when your job is imported there too), and sound outstanding.

[Bill Baker]

Dogs, cats, kids and vacuum tube burns. I checked with other vacuum tube amp manufacturers and asked if they ever had any feedback on anyone being burned by their equipment with no cover cage and the answers came back "no problem".

 I'm with you Frank. I have been dealing with tubes for 10 years now and have never had anybody inform me of any accidental burns. I think pets are smarter than this. They can sense heat just as we can. There will be exceptions of course as I know of a few dogs that are so stupid.......... anyway. If thereare small children around, it's not a bad idea to have a tube cage if offered. At least till the little ones learn. I had tubes in my house with my last thre children. My twins are now 7 and my oldest son 13. Never a burn or even close call.

 Most mistakes are made by the owners themselves because we (opps, THEY) are usually more careless.

 

(I am not going to work for 40 cents an hour so buy Chinese if you must, just don't cry to me when your job is imported there too), and sound outstanding.

 Amen to that!!

[skrivis]

Frank wrote: "Of course not    ". In response to what?, I wonder...

skrivis,

Not much difference in guitar amps and hi-fi amps? What?  

There are only so many topologies for a tube circuit without getting into wildly complex stuff that ends up costing a ton so that your market is limited.

As I said, historically, there was little change in circuits, and the designers got circuits right out of the manufacturer's tube manual. That goes for musical instrument amps as well as audio ones. Hi-fi amps were sometimes a different story, and some more modern guitar amps have also diverged from the more generic designs.

I have an old Tung-Sol tube manual, as well as an old Radiotron guide. Very little has really changed from the days of yore with a lot of current designs.

[skrivis]

The "of course not" was in response to assuming that one of our high powered Fet Valve hybrid amplifiers fell in the class of 100 watt solid state amps the Ultimate 70 can equal in performance.  The answer is "no way".  The Fet Valve Ultra amps win hands down unless you use a pair of Ultimate 70s and the Ultra Bridge, then its really really close.

I was kind of wondering whether output tubes and transformers were doing something that made them superior to SS, thus my question. Your clarification seems to tie in again to your comments about tubes providing a superior front end, due to more headroom in handling the feedback loop.

[yeldarb]

As previously mentioned, A KIT WOULD BE NICE!