A TRUE REVOLUTION IN S. E. T. TUBE DESIGN...

lonewolfny42 · « **Reply #20 on:** 17 Dec 2005, 05:20 am »

Thank you Richard...for listening to the A8's, and the kind words !!!

Chris[/list:u]

eric the red · « **Reply #21 on:** 17 Dec 2005, 06:10 am »

Wolfy-If you plan on purchasing one of the RAM tube amps I will be glad to burn it in for you

lonewolfny42 · « **Reply #22 on:** 17 Dec 2005, 06:12 am »

Quote from: eric the red

Wolfy-If you plan on purchasing one of the RAM tube amps I will be glad to burn it in for you

I'll keep you in mind Eric....

maxwalrath · « **Reply #23 on:** 17 Dec 2005, 06:30 am »

My uncle, who married my aunt in the early '90's, first introduced me to the wonders of superior audio equipment. He has had a Music Reference RM-9 since I've known him. In 1994, ten seconds into listening to his system for the first time, I knew I had a hobby (or whatever it should be called) for life.

Thanks Roger for having a small part in making me appreciate how good a stereo system can sound.

audiojerry · « **Reply #24 on:** 17 Dec 2005, 09:17 am »

Let me add to the well deserved compliments already laid upon Richard.
An extremely well written, informative, and entertaining post, that has fostered a lively thread of comments.

Congratulations and Thanks!

Also, thank you for being instrumental in introducing Mr. Modjeski to Audio Circle. The caliber of our company is getting better all the time. I'll have to check out his website and find out if he has a trial/audition policy.

It's reassuring to see so many intellegent folks associated with the vacuum tube circle.

Roger A. Modjeski · « **Reply #25 on:** 17 Dec 2005, 09:01 pm »

Quote from: JoshK

Let me be the first to say, "welcome Roger!"

I too agree that running tubes at 60-80% their max dissapation is a very good idea and should be adhered to more often. I also am aware that there are many tricks/applications/implemenations that a designer can do to achieve more from a fairly simple design.

I am not dismissing your design abilities at all. I was just trying to make the point that the tube allows this to happen but allowing more headroom. I think we can agree that squeezing 4 watts from a NOS 45 while keeping dissapation at 80% is pretty much a loosing proposition.

Josh,

Have you looked at the graph of power output vs THD that I posted previously? This is at the load and you can add about 20% at the plate. The commonly used application from the RCA manual (RC-11 pg. 86, 1933 and repeated thereafter without modification) gives 2 watts at the plate with unspecified THD (shall we assume 5-10%). Two watts was more than enough power for the times and it seems little has been done by modern 45 amplifier designers to consider new applications.

Applications once written are forever left to rest and copied verbatim by every other maker. Remember, an application is often written to entice the designer (of a table radio at this time) into a circuit that fits his technical and economic needs. The low B+ (275V at 36 mA= 9.9 watts dissipation) of this application is attractive. Note they have 2 lower power ones for those more economical who desire less power. This tube was designed to be a step up from the type 71 (max pwr. 0.79 watts) and a practical alternative to the dismally inefficent and hard to apply type 50. Note that the 50 was rapidly pushed aside for the much more popular 45. I have a Brunswick Panatrope that uses a 50, it's a monster that sold for the price of 1.5 Model T Fords in 1928. The 50 also had to be transformer coupled when resistance coupling was coming on fast.

My application is 310V at 25 mA=7.75 watts along with circuit and load differences. The results are shown on the graph. I fail to see the loosing proposition to which you refer.

roger

Roger A. Modjeski · « **Reply #26 on:** 17 Dec 2005, 09:22 pm »

Quote from: Occam

Roger,

Welcome to Audiocircles. If I'm understanding you correctly, you 'simply' conducted a gradient search of the surface of of various operating points with constraints of specific and overall dissipation, etc.... I'll also assume that your solution of this convex LP program yeilded some local minimas that actually sounds good. Nothing revolutionary, but rather an example of well executed engineering, which is equally rare.
While certainly of fan of dipoles (I've been using one for 350hz+ for the la ...

Occam,

Thanks for your post. I did indeed find some operation points that resulted in very low distortion, which always helps.

I see you know that ancient article on the 6DJ8. Still a great tube, I am applying some others for my SET designs. Since you are are a reader of my technical writings here's a preview of another one coming.

I intend to write a paper on the more complete story of 2nd harmonic distortion theory. I will say here that it must be minimized (but not at the expense of adding other distortions). What listeners don't seem to realize is that large amounts of 2nd is fine for a single note but not for a full orchestra. As I like to say "Please tell me what is the second harmonic of Beethoven's 9th?, the amplifier is having a little trouble figuring it out". Once music becomes a complex signal, the second harmonic argument goes right out the window. The amplifier can only act upon the instantaneous voltage it is given and has no idea what notes are being played. At that point, it's Intermodulation Distortion we had better be taking care of. How many of us have heard our single ended amps make a mess of a symphony yet play a solo voice beautifully?

roger

JoshK · « **Reply #27 on:** 17 Dec 2005, 09:42 pm »

Roger,

I will conceed, I very well could be wrong about my statement about a loosing proposition. I was under the impression it couldn't be done, but that the EML tube could and why you get the outcome you get.

I am really still quite wet behind the ears when it comes to tubes. I am just learning, and I am not an engineer (my training was in math).

Anyway welcome, and I hope you don't take my response as hostile.

Roger A. Modjeski · « **Reply #28 on:** 17 Dec 2005, 10:16 pm »

Josh,

Thanks for the claification on your background. Hope I wasn't too rough, just like to keep the facts clear. There is a lot of guessing, supposing and conjecture around circuits. As a mathmatician you might enjoy that aspect of circuit design. Granted it takes some study to get to that point, but it is worth the effort.

I hope to open a school for audio design some day, but for now I can offer weekend seminars here in Santa Barbara. The local community college has offered to sponsor my classes if I can get 20 people. In a full weekend I could go over the whole design of amps and preamps. Any takers out there?

roger

AKSA · « **Reply #29 on:** 17 Dec 2005, 10:36 pm »

Roger,

Welcome to Audio Circle - I hope you enjoy it here......

I would love to attend your class, I really would.

But I'm Downunder, a great pity!

Cheers,

Hugh

-Richard- · « **Reply #30 on:** 17 Dec 2005, 11:04 pm »

Hi Roger,

Please add my name to the list of enthusiastic participants to your FREE
seminar through the auspices of the local Santa Barbara community college...

What a great pleasure to finally be able to sort out all of the hype,
misinformation and myth surrounding the art and science of amplifier and
preamplifier design...and a wonderfully informative ground from which one
could build their own amplifier someday...

I can attest that Roger is an impeccable teacher and communicator
who has honed his skills to the level of an art form...

This is a very exciting invitation, Roger...I cannot wait to attend!!!
I hope all the audio enthusiasts in the Ventura, Santa Barbara and Ojai
area get in touch with you soon...

Warm Regards -Richard-

JeffB · « **Reply #31 on:** 17 Dec 2005, 11:30 pm »

This thread has been most entertaining.
I am a believer in system synergy and we have heard about how great the RM245 and B200 work together, but there is at least one component missing from this discussion. The "source". I am very curious what was being used as a "source" component. I suspect others might want to know about all the cabling too. Oh, and preamp too, if there was one.

I have been very interested in trying Omega's new Super 3 Bipole with the new hemp dirvers. 6 months away though. Arg!! I am going to go crazy having to wait 6 months.

-Richard- · « **Reply #32 on:** 17 Dec 2005, 11:48 pm »

Hi Jeff,

There is no need to wait 6 months...since Louis is designing his new Hemp
drivers to fit into the cutouts now being used by the Fostex drivers in the all new
Super 3 2V Bipoles...it should be a simple matter of droping them into place
once they are ready...

According to Vinnie Rossi, whom I trust completely...the Super 3 BP's even with
the Fostex drivers are extraordinarily special...and I am very excited about
receiving my pair within the next few weeks...

Call Louis...a lovely chap to work with believe me...it was Louis who told me
about Roger and his new SET amps...

Warm Regards -Richard-

JoshK · « **Reply #33 on:** 17 Dec 2005, 11:51 pm »

Roger,

I'd probably try my best to make it out there to attend. BTW, I was born in Lompoc and my mother grew up there. I am a Cal Poly alumn, so I do know the area. Wish I living out there again.

BrianB · « **Reply #34 on:** 18 Dec 2005, 07:18 am »

Hi all,

This is my first post on Audio Circle. I have known about this site for a long while, but an audiophile friend finally convinced me to register...

Being the U.S. importer for Yamamoto Sound Craft, one of the first things I did after registering was conduct a search for "Yamamoto" - and this thread appeared at the top of the list I got back. So I figured I'd start here.

Let me begin by saying that I was immediately intrigued by the topic of this thread, as RAM Labs called me last week to ask whether I'd be interested in selling Music Reference amps and preamps in my little shop. In fact, I am VERY interested, as I've always been impressed by Roger Modjeski's designs. And so I was grateful for Richard's detailed description of his experience with RM-245.

That being said, I would like to comment on the following passage from Richard's initial post:

Quote from: -Richard-

I was thinking about the Yamamoto A08S because of the raves Srajan and Jeff Day said about it. MOVE OVER Yamamoto. Here is a true legend of American audio, Roger Modjeski, who has developed a SET amp that delivers TWICE THE POWER from the same tubes and gives enormous control over biasing and even negative feedback, or no feedback, as desired...for less than the Yamamoto... and does not use a rectifier tube. And Roger’s circuit design has good control over damping which means good control of the speaker and a very low noise floor.

It is important to point out that the Yamamoto uses the 717A tube which will become increasingly hard to find. The 80 which is their rectifier tube, it is already expensive and becoming rare. This constitutes built-in obsolescence. And I like the design of Roger’s new SET’s much better.

Richard, given that you seem to be arguing against anyone purchasing a Yamamoto A-08S amplifier, I'd like to make the following points:

1) Shigeki Yamamoto is rapidly becoming a "true legend" of Japanese audio.

2) While Roger's design is VERY IMPRESSIVE in its ability to safely deliver twice the typical power of 45/2A3 amps, power is not everything - at least not in the world of SET amps. In my opinion, tonality is the most important ingredient of an amplifier's presentation. And I'm betting that both the RM-245 and the A-08S have exceptional but rather different tonalities. In other words, if you have the right speakers, the choice between these two amps may boil down to personal taste more than anything else.

3) Yes, the A-08S uses tube rectification, but is this really a bad thing?

4) I'd be willing to wager that the DC-heated A-08S is at least as quiet as the RM-245, if not more so...

5) Please note that Yamamoto Sound Craft has an exceptionally large inventory of 717A driver tubes and 80 rectifier tubes that are available to all A-08S owners. In other words, if you purchase an A-08S, you need not worry too much about tube availability.

6) We are currently selling 80 rectifiers to A-08S owners for $40. Does this price fall in the range of "expensive" in your opinion?

For the record, I am NOT arguing against the purchase of a Music Reference amp here. In fact, there are few companies that I would recommend more highly! But I DID want to set the record straight regarding Yamamoto's offerings.

Cheers,
Brian
Venus Hi-Fi

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-Richard- · « **Reply #35 on:** 18 Dec 2005, 08:36 am »

Hi Brian,

I would like to welcome you to Audio Circle...

However for the record...I am not pleased with your shameful self-promotion
of the Yamamoto amplifier on this thread which is devoted to exploring the
amplifier designs of Roger Modjeski among other things...to bring his
Revolutionary Single Ended Triode amplifiers to the attention of AC members
who might find it of interest in their search for musical nirvana...

You own an audio store and you sell the Yamamoto...

Two Channel forum is not the place to advertise your products...
there is a manufactures forum for that...which you can apply for by getting
signatures of AC members who find your conduct, products and ethics worth
their while enough to sponsor you...

When I discussed the Yamamoto's built-in obsolescence it was to alert AC
members of the risks they take in purchasing this foreign product...
I did not discuss the issue of repairs should that become necessary which
is yet another important consideration...

We American's have magnificat designers in our midst that deserve our attention
and our support...and Roger Modjeski is certainly one of the most important of
these innovators in the world of audio...

We are being inundated by a plethora of Asian products that have had the effect
of sweeping our own cultural hero's from our attention...which is most unfortunate...

I am trying to correct, in a very modest way, this horrible imbalance and
unfortunate trend...

I am ready to state in no uncertain way that I support American amplifier designers
first and foremost...

When it becomes clear what Roger is offering us...what I think are beautiful designs...
twice the power from the same SET tubes...more control over how those tubes are
integrated into the synergy of ones audio system...superior technical support...
and the chance to own an amplifier made by an American legend...his Revolutionary
new SET tube amplifiers will find an appreciative audience...

Warm regards -Richard-

audiojerry · « **Reply #36 on:** 18 Dec 2005, 03:15 pm »

Welcome, BrianB.
Richard got the ball rolling by posting an excellent, informative, and fun-to-read review, which has fostered a lot of interest and high quality contributions from others, including Roger Modjeski. This is why AC is such a great place to visit. The sharing of information and the respectful exchange of ideas and differing viewpoints are extremely important assets of AC, and it bothers me when attempts are made to suppress it.

Richard, I enjoy reading your posts and appreciate your willingness to share your views so eloquently, but I strongly object to your attempt to control the content of this review.

I may be wrong about the rules of posting here, but I believe BrianB was very polite and respectful in his reply to your critical comments, and I believe he had the right to defend. He said nothing critical of Musical Reference, and was trying set the record straight about Sound Craft.
It's fine if Richard wishes to take a patriotic stance, but I believe most of us are able to make our own decisions based on the information that's presented. If BrianB or anyone else wants to provide additional relevant information, we should all welcome it.

On the other hand, if things start to turn into a political debate, then a new topic should be initiated elsewhere. BrianB's comments were very approriate to the topic.

I, for one, appreciate learning more, and welcome differing and opposing views, as long as we keep things respectful. Let's continue trying to encourage the exchange of ideas and trying to attract contributions from a continually growing circle of interesting members.

BTW, there is more info about the Yamamoto on Six Moons:
http://www.6moons.com/audioreviews/yamamoto/a08.html
Decide for yourself it you want to make use of it.

srayle · « **Reply #37 on:** 18 Dec 2005, 05:50 pm »

Hey Y'all,

Yikes! what an interesting and spirited thread!

Brian B., welcome, I've had a few consultations with you about audio, and had a chance to audition the wonderful little Almarro A205A integrated thanks to the tryout program you've got going thru audiokarma.org.

I think your response in defense of the Yamamoto's fine qualities and your clarification of tube availability was appreciated by those following this thread and debating the merits of Roger's amplifier designs and Yamamoto's. To me, pasting that large high resolution picture of the amplifier made the post feel like a sales promotion. The same post without the picture might be seen differently, as more informational and less promotional. My two cents...

audiojerry · « **Reply #38 on:** 18 Dec 2005, 07:46 pm »

Quote from: srayle

To me, pasting that large high resolution picture of the amplifier made the post feel like a sales promotion. The same post without the picture might be seen differently, as more informational and less promotional.

Very good point, srayle. I agree.

-Richard- · « **Reply #39 on:** 18 Dec 2005, 07:53 pm »

Hi Srayle,

Yes...you have captured perfectly the impression I had when I saw that giant image
of the Yamamoto attached to Brian's post...that was the first time the Yamamoto
looked ugly to me...and it set me off a bit...

However I am grateful to Brian for helping me to flesh out feelings I have about talented
American designers and innovators which I feel are overlooked and unappreciated
because as a culture we spend enormous energy on movie stars and athletes...

I had never actually put those ideas into words before...feelings which audiojerry
characterized as patriotic...well perhaps they are...if by patriotic one means
a profound appreciation for the talented men and women that are part of ones
own culture...

Of course audiojerry you are right...information should never be suppressed...
when I wrote that post it was late at night...the playground of the spirit world...

Warm Regards -Richard-