"HUGE " Mistake !! " MASSIVE " Change !!!

[Dale W]

If nothing else i'm honest an own up to my mistakes. I was so excited about firing up my tubes , and did not have a accurate multi meter at home so i never checked the bias and just ran with it .

Tubes and everything need to burn in and knowing that i was still very impressed with the amps last night " BUT " tonight i brought home my digital meter from work. Heres what i found.

Amp 1 - .17 on one tube and .93 on the other

Amp 2 - .23 on one tube and .51 on the other.

Now all 4 are set at .70 and the change is HUGE .

These amps kick out the bass like you would'nt believe and 7 to 8 o'clock on the volume pot is perfect. 11 is awsome and 1 o'clock is almost more than a lascala or my ears can take.

I listened to some audio research tube amps costing 10 times what these mark III's cost me and i allready prefure these amps. The research were hooked to some 2003 k-horns and i'm olny running my dynaco's on the lascalas right now.

Ethier craig or jeff or both did one hell of a job on the amps and pre-amp. Thay will both be getting a real good letter of recomondation from me.

[Deang]

Craig put these in triode?

How much power are you running now?

Watch your ears with those Scalas. If you're not careful, you'll end up like Craig -- calling your kid in to ask, "how does it sound"?

[lynnm]

Dale

Where did you get the 700 mv. bias value from ?

That value may be within tolerable limits but depending on the plate voltage setting it could be too high.

My advice would be to back them down to about 400 mv. until someone with more expertise than I advises otherwise. I fear you may be pushing those tubes too hard.

[Dale W]

Dean: yes full triode mod's / triode mod dropped me down to 30wpc from 60 in ultra.

lynnm: craigs instructions .70 vdc maximium

[NOSValves]

Lynnm,

Trust me on this .70 per tube is absolutely perfect for a set a KT-88s . Trust me this has been researched and will be perfect. That translates into 70 ma per tube perfect ! Although Dale you may be fine to turn them down since your not using the full volume of the amps set it at .60 and you will probably never tell the difference and your tubes will last longer.

Dale,

You should be spanked that was not good for those tubes but I'm sure they will be fine

Deanomiester !!!

Are we rethinking the Triode here ? It Rocks dude !! I have had nothing but great comments on a 299B being in triode and now Dale absolutely loves the Marks in triode. I told you to buy a set of these and quit messing with that SS rectified newer stuff but my good buddy Dean wouldn't trust me The Mark III's are just what Mark Deneen said they are incredible amps if modded right and by they way everyone Mark Deneen should be given equal billing on this setup he taught me everything I know about modding tube amps and always helps me along the way !!

Craig

[Deang]

I haven't said much about the Quicksilvers. I know I have this propensity for singing praises for something, and then as I spend more time with a piece -- I begin to zero in on it's deficiencies.

The Quicksilvers sound so good with the RF-7's -- I just don't want to mess with them. I only asked Dale if the Dynaco's were in triode or not because I was curious how much power he was running.

Regarding the SS rectification bit -- I mentioned to you before that Saul Marantz used it in the 8B. Anything done right -- sounds good. I appreciate the speed and drive it gives me.

http://www.aikenamps.com/UL.pdf

[sunnysal]

I am confused...I thought that all dynaco amps were designed to run a bias of 1.56v?...assuming you are still using 11.2ohms of bias resistors, or has this mkIII been extensively modified, tony

[NOSValves]

Sunny,

These are completely modded amps really the only original parts under the chassis or above are the transformers !! They are now using 1- 10 ohm 1% resistor per tube for biasing. The original design was done because common Multimeters were so far off they made it so the 1.56V of a D cell battery could be used as a point reference. So now to get proper bias you set each tube to .70 and your output tubes are balanced ! That is another benefit setting both tubes to 1.56 could end up with one being 95 and the other being 61 it depends on the tubes themselves. Almost every tube amp from every manufacturer from that era had real short comings in the Bias adjust setup. Scott, EICO, Dynaco, Fisher ....ect. I personally wouldn't own a self biasing amp from my experience with the way tubes differ in there characteristics there is just is no true match pair or quad out there !! I have biased many many amp and used matched quad in almost every amp and I have never seen a set that draws the same bias current on all for tubes after being perfectly balanced .

Craig

[NOSValves]

Dean,

Great link but keep in mind what the author ended the article with.

" This Author believes for sheer listening pleasure the Ultra-linear amplifier represents the best that can be achieved at the present state of art." Written in November of 1951

Tubes and designs have come along way since 1951

Craig

[sunnysal]

thanks craig, now I get it...tony

[Dale W]

Sorry about that craig, i know that was a foolish thing to do.

Man do these things ever sound "GREAT " . I spent 4 hours last night just enjoying the music instead of listening for faults.

I had a leather chair centered between the lascalas about 6 feet apart and as i leaned back and listen , the music was right inside my head just like wearing a walkman. Super clean crisp mids with soft gentle highs and bass coming at its leasure. I was hearing things in recording that i never new were there before.

I hated to shut them down and go to bed.

I might just be hunting for another pair of these in the future.

[NOSValves]

I'm really relieved that this has all came together so nicely after all the mishaps that happened actually getting them to you. You sure have me missing them things again and just when I have about forgot about them LOL !!! They are some amazing amps !

Craig

[NOSValves]

Dale,

The next time you spend about 4 hours or so listening to them when you get done before you shut them down set the bias. Then forget it for a few months I put allot of hours on those tubes and they should be well burned in so if you let the amps really settle in and set the bias when the amp is hot your all set and just check them every couple months.

Craig

[Deang]

"Tubes and designs have come along way since 1951"

I don't understand how someone with your knowledge can make that statement. I don't agree at all. Reinventing the wheel cannot be equated with "coming a long way". Consider the first triode amp was built in 1907, and that the Ultra Linear circuit that came about 45 years later, was at the time -- considered quite a leap in fidelity. So, what has happened since then, except the regurgitation and tweaking of circuits that have been around for 75 years or more. I would argue that any improvements in any of these designs are mostly due to better tolerances in manufacture, superior parts, etc, applies equally to all the old circuit designs -- including Ultra Linear designs.

I can't tell a hill of beans difference between the AE-35 DJH I had and the Quicksilvers. How can that be? Is my hearing THAT bad?

The "Author" of the .PDF document I gave the link for was David Hafler. It is a copy of the original paper appearing in the 1951 November issue of 'Audio Engineering'.

The following is from a small book put out by Sonic Frontiers called 'A Taste of Tubes'.

In 1934, W. T. Cockings seminal article on "quality amplification"

appeared in the British DIY publication, Wireless World. In it, Cocking

suggested that 5% distortion was too high for quality amplification.

He went on to state that "the aim being to reproduce in

the listeners own home exactly what he would hear if he were in the

studio."

This statement marks the conceptual origin of the era of high fidelity,

insofar as we are able to trace it. Cocking is recognized as the

harbinger of high fidelity not only because he was influential and

authoritative, but because his amplifier was to evolve, by deliberate

steps, into the famous Williamson amplifier.

After explaining his approach, Cocking compared triodes to pentodes

and found triodes preferable for their ability to damp a moving-coil

loudspeaker at resonance. He next compared push-pull to single-ended

operation and concluded that the latter produced objection-able

2nd harmonic distortion.

Cockings amplifier soon became known as "The Wireless World

Push-Pull Quality Amplifier". This seed-pod or germinal amplifier

was destined to become the touchstone of tube design for nearly

twenty years.

Williamson Stirs the Pot

In April, 1947, D. T. N. Williamsons article "Design for a High

Quality Amplifier" appeared in Wireless World. Williamson echoed

Cockings words when he summed up his analysis of the require-ments

for high quality amplification: "It appears then that the design

of an amplifier for sound reproduction to give the highest possible

fidelity should centre round a push-pull triode output stage and

should incorporate negative feedback."

Thus, the evolution of Cockings "Wireless World Push-Pull Quality

Amplifier," (as begun in 1934), ultimately culminated in the famous

Williamson amplifier of 1947. The distinguishing feature of each

incarnation of this amplifier was the use of triode tubes (actually,

KT66s wired for triode operation) in push-pull configuration. In

spite of their reduced power output, triodes were preferred over

pentodes because their distortion products were found to be less

objectionable. This meant that, to obtain a given power output, more

money had to be spent. Thus the identification of high fidelity with

higher cost began to take root in the public mind.

In 1946, Avery Fisher introduced the first commercial high fidelity

system. It included a 50-watt triode amplifier, Jensen co-axial speak-ers,

AM/FM tuner, preamp and phonograph. The $1,200 price,

however, put this model out of the reach of most music lovers.

Other companies like Altec-Lansing, Brook, Bogen, Bell, and

RadioCraftsmen also joined in the fray. T o s ave money, audio

enthusiasts could buy hi-fi components in kit form from companies

such as Heathkit, Eico, and, later, Dynaco. The kit-building craze was

fueled by the large numbers of post-WWII military-trained

electronics technicians.

The Pentodes Revenge

By 1949, Williamsons triode amplifier had become the prototype for

high quality amplifiers the world over. In the face of this enormous

interest, there arose a new generation of pentode amplifiers to chal-lenge

the long-standing triode tradition. The pentode movement

consigned to public address systems early on by engineers and audio-philes

alike was reinvigorated when new techniques were discov-ered

that caused pentodes to sound/perform more like triodes.

Quads Potent Pentode Recipe

Three companies in particular stand out for their achieve-ments

in pentode amplifier design. In 1945, Peter Walker of

Quad found a way to dramatically reduce the high-order pen-tode

distortion products. Taking a clue from Blumlein, Walker

found a way to turn the high pentode gain into local feedback. To

obtain this feedback, Walker incorporated a tertiary cathode winding

within his output transformer.

This technique produced local feedback in accordance with the AC

impedance of the cathode winding. This more sophisticated form of

feedback provided a greater benefit than loop feedback alone, since

there was only one high-frequency pole to create phase shift. Unlike

loop feedback, the cathode feedback remained effective at the fre-quency

extremes, thereby reducing the high-order distortion products

associated with pentodes at no expense to power output!

McIntoshs Pentode Pie`ce de Resistance

In 1949, Frank McIntosh and Gordon Gow took Walkers technique

a couple of steps further in their 50W-1 amplifier. First, they

increased the number of turns in the cathode winding (Fig. 7) to

obtain correspondingly more local feedback.

Second, the plate and cathode coils were wound adjacent (bifilar) to

one another to create a "unity coupling" between the two windings.

This reduced transformer leakage reactance by a factor of 3-to-1,

thereby extending transformer bandwidth and reducing phase shift.

The reduced phase shift translated into more effective loop feedback

at the frequency extremes, enabling McIntosh to claim the lowest dis-tortion

across the widest spectrum of any known power amp.

The editors of Audio Engineering hailed the McIntosh as "the first

major change in years in amplifier coupling circuit principles." No

mention, however, was made of the Quad amp.

Hafler and Keroes Go Ultra

In 1951, David Hafler and Herbert Keroes approached the pentode

from a different angle. They returned a portion of the plate volt-age

to the screen-grid (Fig. 8). This local feedback loop became

known as the "ultra-linear" connection. It soon formed the basis

of the Acro Ultra-Linear amplifier. Keroes, a transformer expert,

knew that the screen-grid was a non-linear input terminal where

feedback is concerned. Nonetheless, he found that the tapping

point could be adjusted to enable linear feedback action. This nar-row

window of operation was claimed to provide "ultra linearity."

In their own words: "We have achieved a new tube type without

designing a new tube. This tube is neither triode nor tetrode, but its

improved linearity over either of those types justifies the designation

ultra-linear." In reality, this statement applies as much to the Quad

and McIntosh amps as it does to the Ultra-Linear amp.

Nonetheless, because the Quad amp was little known in the US, the

ultra-linear technique became widely adopted. During the Golden

Era alone, more than twenty different manufacturers adopted the

technique including Marantz, Harmon-Kardon, Fisher, Scott, Eico,

and Dynaco. Indeed, the very name, "Ultra-Linear", was to become

generic; in that it ultimately came to refer to the technique itself,

rather than to the amplifier that inspired the name.

[NOSValves]

Well really both of you are reading things into my statement that just are not there maybe I should of worded it differently !! I didn't mean to say that there has been major leaps in tube circuit design but there have been major circuit tweaks found since 1951 such as running these ultra-linear circuits in Triode. But that article leaves much to be explored beyond staight ultra-linear operation. I personally think to my taste every amp I have wired into triode sounds leaps and bounds better. This option isn't covered in the article at all. This is why Dean brought this article up about Triode versus Ultra-Linear. That article does not cover a Ultra-Linier circuit wired in triode. It is just comparing a Triode Tube circuit to a Ultra-Linear. Does this make any sense with my point ?

Craig

[Deang]

I think wiring Ultra Linear in Triode just gets you closer to the 3rd order distortion faster.

I think at this point, I have just decided I am more interested in keeping the amps in Class A as much as possible, as opposed to triode operation. I don't know how much Class A power I have, but I bet I'm in it most of the time.

[Dale W]

Dean : I truely hope your search for the holy grail of sound from a tube amp is found some day. You sure seem to be trying hard enough to find it.

I wish you were close enough for me to lend these tiny dynaco's to you for a week or so. For what they are and what they cost there sound is unreal.

I know a lot of you set guys are useing way less power than the 30wpc offering i have and even my lascalas cannot take eveything these mark III's have to give.That being said and your taste for volume and heart pounding rock music at times , i think even you would have to be impressed by there power. Then again the pantheon pre-amp probably helps the chain in my system as well.

Good luck in you search dean : DALE

[Deang]

Bad verbiage on my part. I simply meant rewiring, so a beam or pentode tube behaves as a triode.

As far as the Quicksilvers go -- I have no idea where Mike Sanders got the circuit for these. They do sound very good however.

[Deang]

So Mark, you tell me -- what the hell are we looking at here?

I paid extra for the duct tape.

[NOSValves]

Dean,

Get a schematic it would make this much easier !! I wan't to see one for that amp there has to be one out there somewhere !!

Craig