The " PFA TRIPLE 6005 "..... DIY tube amplifier of 2022.

[Kannan]

the best sounding amps in THIS world are NOT ever made by EEs and pHDs particularly, but by JUST a few people world-wide, who LISTEN and build, and have a passion for it all. Never forget that !!

An absolutely forgettable and a totally unnecessary comment and most importantly a classic example of oxymoron.

1. You repeatedly keep stating in all threads that among your mentors are two ENGINEERS whose name I forget.
2. Next, an engineer need not necessarily have to have a backing of an engineering education. Many DIYers are not EEs or PHds but design proper amps as they have knowledge of circuits through expereince and hands-on learning.
3. All amplifiers and other audio components like preamp, DACS etc. are built on two facets, developed and built through engineering and then voiced further by listening.
4. Just because some do not agree with your design philosophies based on certain engineering standards, does not mean that you are wrong in your ways as the ultimate test are ears like you say and I agree with it, and the final goal of a system is to get the music to play the way one likes it if the skill sets are available to do that.
But again that design goal is purely yours and many may not agree with it as there is no universal constant as far as audio is concerned.
Kindly stop repeating your misplaced "My Way is Highway" philosophy and just accept that with humility and carry on with your journey without being condescending to others.

It does get tiring beyond a point. I diligently avoid your posts, but then you do need a wake-up call when you infringe on others sensibilities.

Have a great day.

 

[drlowmu]

Hello Kannan ,

The Electronic Engineer whose name escaped you was an audiophile - friend Dr. Charles A. Halijak, past Dean of E.E. at the University of Alabama in Huntsville. Specifically, I posted twice on HFV - his 1989 letter to me. " Figure of Merit of a Power Supply ".

After travelling over forty three years on an audio design path, I safely and securely have the right ( and duty ) to say .......some of my contents are literally " my way or the highway ". But today only maybe 2% of tube amps apply this approach. It is the polar opposite of what any EE learns in school about power supplies ( ie: Critical Inductance ).

( Here is some of audiophile Dr. Halijak's work : https://www.researchgate.net/scientific-contributions/Charles-A-Halijak-2017834553 )


Yes, I understand your above post. In several parts I certainly agree with you.

Listening to various tube amps at audio shows across the USA, designing and building amps for myself, I believe I have paid my lifetime's dues, to speak as I do.

I would agree, that the power supply alone does not make the world's best sounding tube amp, and that there are other considerations that can come into play. But then Kannan, I realize when you ( and others ) post, you likely have not heard what I am discussing, amplifier wise, even ONE time . I have to give that fact its proper due.

I appreciate you taking the time to post. You did so nicely . The truth is sometimes hard to understand and to accept, for all of us humans.

Feel free to ignore my posts. It does not bother me.

Best wishes to you.

Jeff

 

[RtoR King]

I though this bashing of EE's and professional electronics technicians was banned by the moderators in previous posts?

Perhaps it's time HiFiVision takes it's rightful place on the long list of audio forums DrLowMu has been banned from?

 

[drlowmu]

Goodness, I certainly have never ever even mentioned " professional electronics technicians " - anywhere.

As to EEs and pHDs, what I pointed out, about designing the best performing and best - sounding tube type audio amplifiers in the world,....... is totally true. It is hardly " bashing ". I believe there is little wrong with speaking the known truth .

There is just a small handful of people world-wide, people who primarily LISTEN and build, and who easily develop the best sounding tube amps. That is my long-term observation, my point and commentary.

Jeff

 

[RtoR King]

Goodness, I certainly have never ever mentioned " professional electronics technicians ".

As to EEs and pHDs, what I pointed out, about designing the best performing and best - sounding tube type audio amplifiers in the world,....... is totally true. It is hardly " bashing ". I believe there is little wrong with speaking the known truth .

There is just a small handful of people world-wide, people who primarily LISTEN and build, and who easily develop the best sounding tube amps. That is my observation, my point and commentary.

Jeff

So then no EE or pHD world wide is capable of designing a good tube audio amplifier?

This is absurd!

 

[drlowmu]

So then no EE or pHD world wide is capable of designing a good tube audio amplifier?

This is absurd!

I am certainly not talking about a " good " tube amplifier.

I am talking about a handful of this world's best-sounding, and best-performing tube amplifiers.

Performing is NOT on an O'scope, but mostly as to how it plays back music.

Listening to design has been this way for decades now, and anyone with decades of great audio ( not electronics necessarily ) experience, easily knows this.

Jeff

 

[aeroash]

@drlowmu Let me try to simplify what most are trying to tell you.
The way you speak, you're not going to make any friends nor have respect, appreciation or admiration.

A simple change in language will be more effective for people to want to take notes and bring your work to light, if that's what you want, or else continue as is and keep pushing away well-meaning folks, up to you.

 

[Subbu68]

So then no EE or pHD world wide is capable of designing a good tube audio amplifier?

This is absurd!

EEs and PhDs can see what others cannot see in these "pro" designs, engineering wise and cry out in anguish and many a times in vain

@drlowmu Let me try to simplify what most are trying to tell you.
The way you speak, you're not going to make any friends nor have respect, appreciation or admiration.

A simple change in language will be more effective for people to want to take notes and bring your work to light, if that's what you want, or else continue as is and keep pushing away well-meaning folks, up to you.

And avoid sending unsolicited personal messages and advise on the forum that contradicts well established and proven EE theories

 

[drlowmu]

@drlowmu Let me try to simplify what most are trying to tell you.
The way you speak, you're not going to make any friends nor have respect, appreciation or admiration.

A simple change in language will be more effective for people to want to take notes and bring your work to light, if that's what you want, or else continue as is and keep pushing away well-meaning folks, up to you.

OK, That was VERY nicely written. Thank you.

At my advanced age, ( recently turned 78 ) it is a bit difficult, but certainly not impossible, for me to try to change how I present things.

But henceforth, I will TRY to write in a manner that is more acceptable to the majority, even if I am presenting a minority finding or point of view. I feel overall, the HFV Moderators have been superb, in allowing me to share my own audio adventures herein, and intuitively, I do think they sense my sincerity. ( The human-being aspect !! )

Actually, I would like people to engage me more-so, and try these things for themselves ( like an LSES power supply , 6 Ohm L1/C1/L2/C2 filtering topology, Direct Coupled two stage SE amps, be it 2A3, KT88, KT150, or multiple 6005s, two-way ALTEC / GPA speakers with a 15 inch and a 1 inch, and new high-performing wiring configurations ).

As for your own recent work with speaker wire, it would be very nice if we spoke, interacted, I get updated, and see if any suggestions need to be shared. You can implement that private Forum communication by initiating it on your end, easily. My hands are tied, as is.

Best wishes,

Jeff

 

[drlowmu]

EEs and PhDs can see what others cannot see in these "pro" designs, engineering wise and cry out in anguish and many a times in vain


And avoid sending unsolicited personal messages and advise on the forum that contradicts well established and proven EE theories

Dear Subbu68.

Seventeen years ago, on Audio Asylum, I introduced Dennis Fraker and EE Dean Dr. Charles Halijak's concept of using NON CRITICAL filter inductance in tube amp power supply chokes. Despite being chastised and thrown-off Audio Asylum, for introducing something " against the text books ", two EEs back then ( John Swenson and John L. Hasquin ) actually TRIED it, posted their results, and they both loved it.

I saved, and can thus send both those EEs' 2005-2007 published Forum complete postings, to you, or to anyone who so requests it from me, to read and judge, with an open mind, on their own. To learn - more about this.

The resulting increased musical enjoyment these two EEs received, has seemingly not been improved upon, since then, as their preferred approach. It goes 100 percent opposite what is taught in EE school. How can that be ???????

Who is crying in vain.? Please tell us, what really counts Subbu68,..... a textbook's formula ...... or the actual performance, ie: what we actually hear ???

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

A couple of days ago, when I found out what was the best 10 uF film cap ( from someone very experienced in such matters ), I sent you a private message. I had just been reading the one day-old-post on Audio Asylum ( Tube DIY Forum ) on the ACA, Nelson Pass' low budget amp, and how to improve it. One AA post reminded us all that the circuit starts with as he said " a nasty " cheap 10 uF electrolytic coupling cap, in series with the input signal, which needs to be replaced.

Subbu68, this above ACA circuit information, seemingly to me, does not at all ................" contradicts well established and proven EE theories."

When I found out what was the best 10 uF film cap, and was specifically advised " it is really the only one to buy in 10 uF ", I sent you by HFV private mail, the A.A. ACA article, and a precise description of the ideal 10 uF cap, and where to obtain it.

I never heard back from you, with any decent " Thank You " for specifically thinking of you, and offering you this new information. I HAD NOTHING TO GAIN, we never speak, I WAS TRYING TO HELP YOU.

Instead, I see here today, public Forum condemnation,....... for informing you privately.

BTW, I totally understand how you came about to do this. I do not condemn you in any way.

My post today at least represents publicly, my side on these two matters you have brought up. Take a moment and think about both these things that seem to bother you, from my explained-herein perspective please. Thank you very much Subbu68. Peace between us !

Who wants to review EEs Swenson and Hasquin's AA posts on tube amp power supplies ?? Hopefully, any and ALL of the FMs who are the least bit critical of me !! HFV PM me and I will cheerfully send them to you.

Have a nice day.

Jeff

 

[drlowmu]

GOODBYE to 2021 HFV Stereo Single 6005 AMP, S/N #1.

I was, uniquely for me, commissioned in 2021 to build the single - 6005 stereo amplifier, subject of the HFV amp build thread that was started that year. I built two, one for me and one for my client. He sought from me a " special one Watt SE tube amplifier ", to power his high efficiency Lowther drivers in his Beauhorn enclosures.

As of 1-12-2023, as seen in a post only several entries above, I got the 6005 amp's design optimized to a satisfactory to me ( goose bump ) level.

What may be fine for Lowthers, does not apply to my own high efficiency speakers, and what many of my audio friends run as speakers. This would typically be - various ALTEC LANSING two-way systems, with typically a 15 or 16 inch and a 1 or 1.4 inch compression driver. It takes muscle to control on a truly ideal basis, any 15 or 16 inch ALTEC or GPA woofer !!! Especially so, when the driver is mounted inside a Voice of the Theatre A7 horn-reflex combined / enclosure.

On 12-12-22, I changed my home's system from Stereo to Mono, to seriously evaluate a new 16 inch driver. I have suspected that my stereo single-6005 tube 2 Watt per channel amp did not have enough power - to ideally operate the new driver ( rated 104.5 dB in my enclosure !!!! ). I crudely externally paralleled both channels, to hear a " 6005 DOUBLED ". Why not hear it, .........I have been planning a " TRIPLE " for a year !!!

The DOUBLE could be converted to a SINGLE, in ten minute's time. After A-Bing this, there is truly no contest. The paralleled 6005s transformed the music's delivery into my room. All the more incentive to build two monoblock TRIPLE 6005 amps. I expect these TRIPLES to easily become an end-game amplifier.

I decided yesterday, that I would not resell my SN #1 stereo single amp, unless to another Lowther Beauhorn owner. I usually don't sell my builds to others. I will DISASSEMBLE it - and re-use parts and assemblies I already like, inside the new TRIPLE 6005 monoblocks.

Fortunately, the 2021 Single Stereo 6005 amp was designed by me in a modular circuit function manner. I can easily unbolt the circuit modules from the Stereo Single amp, and apply them to the Monoblock TRIPLEs. We see this modular aspect more clearly in the denoted photo below :



From the top, left side:

1) D.F.F.F. Xs 2 for Ra, stands for " Dennis Fraker Final Filter, two L/C filters in series, specifically to power the PLATE resistor ( "Ra", IN RED ) of the Input tube. The most sensitive circuit location in the amplifier.

2) D.F.F.F. Xs 2 for G2, stands for " Dennis Fraker Final Filter, two L/C filters in series, specifically to supply B+ to the 6005'5 G2 or Grid #2, the second most sensitive circuit location in the amplifier.

3) The encircled " 6005 Rk Bypass " film cap components ( to which is NOW also added a better-wired 5 uF GTO cap ) optimizes the Final's tube cathode resistor, and it's music signal return path to ground. In almost all tube amps, this circuit area is overlooked unconsciously, never optimized. A single electrolytic :-( Rk cathode bypass capacitor will be commonly be seen there. How sad to me this fact is, versus what is possible.

I started ordering some truly "yummie" new parts for the TRIPLE circuit's needs yesterday, and in a month, the above pictured SINGLE Stereo 6005 amp will cease to exist in my home. Thanks for looking. The die is cast.

Jeff

 

[RtoR King]

"Who wants to review EEs Swenson and Hasquin's AA posts on tube amp power supplies ?? Hopefully, any and ALL of the FMs who are the least bit critical of me !! HFV PM me and I will cheerfully send them to you."

This was already vetted on another forum. IIRC the Kilpsh forum. There is no record of Swenson or Hasquin possessing an accredited EE degree. And I don't believe they ever personally stated that either. This seems to be your claim in an attempt to put some credibility to your questionable technical claims. An informal inquiry to the university you claim Hasquin attended yielded no results. Swenson also has a business building audio accessory products, that have been tested, and produce little to no benefit as advertised. See the ASR reviews.

Dr. Halijak does seem to be quite legitimate. His papers are rather advanced the topics and quite impressive. Which brings up another quandary. Where is this paper in non critical inductance you claim he wrote? Based on the highly advanced electronics research he did publish, I just don't picture him playing around with 1930's audio amplifier designs.

 

[drlowmu]

It is really nice to have you here today to provide a counter point. You are almost the perfect example.

Perhaps you and your friend should spend more time learning about audio and music, perhaps even listening to it, rather than trying so diligently, and so unsuccessfully to disprove or discredit me, in any far-fetched manner you can.

Degrees from a college are not important, the PRIMARY thing that counts is audio performance when listening.

I wouldn't care if a monkey developed it ! If there is a better way, I want to know it - and employ it if possible.

Dr. Halijak had Stancor build for him, for his personal use, 1 HY., 8 Ohm audio chokes, on a custom basis.

Have you ever studied "Critical Inductance Theory"? Do you even know what that specification means, in relationship to Critical Inductance textbook theory ?

The 1989 letter to me, entitled " Figure of Merit of a Power Supply" I have taken the effort to post in it's entirety, twice on HFV. Why, because I totally understood ( from building and listening ) its extreme importance .

You never seem to address the message, and only concentrate your time on the messenger.

What is there to gain, to learn, and to advance in our audio understanding - from what you posted today ?

Jeff

 

[RtoR King]

DrLowMu,

As long as you keep posting these unproven outlandish requirements for building a great audio amplifier, you are going to get push back.

1) The need for heavy gauge hookup wire in front end signal circuits. You have claimed hundreds of amps are required for rise times. If such phenomena did exist it is easily measured.

2) The need for expensive RF capacitors to support these "hundreds of amps". If you like to use them fine. But people here should realize they are hardly required for good, even great, performance.

3) The need for critical identical wire lengths to eliminate timing skew? In a modern PC, yes this is critical, But an audio amplifier? Absurd!

4) It has been explained to you many times by many people why your amplifiers sound "fast". And if you like that, fine. But a properly designed audio amplifier is not supposed to alter the signal in any way except gain. There are a plethora of effects processors, both hardware and software based to add gimmicks to music.

The list could go on......

Then you say engineers do not have any listening skills? How can you make wide broad statements like that? Where is the data to back them up?

May I suggest you study some basic electronics and physics. You got the music part down. Now try to learn why you hear what you hear and why faithful audio reproduction follows a different path.

 

[drlowmu]

The more you open your mouth, the more you become the PERFECT example, to those of us who build and listen at high performance levels.

You are sadly ill informed and you have terribly misquoted me SEVERAL times in your posts today.

All my statements are PROVEN, re-read Herb Reichert's RMAF show comments , year 2016. Read what Herb wrote about my audio Mentor, Dennis Fraker of Serious Stereo. I build similarly as my teacher, but never ever as good, as he does.

Besides being ill-informed, you are a waste my time, and so, I shall henceforth try to ignore you.

I hate to see you smearing me and worse yet, mis-leading good audio people, but you HONESTLY do not know any better, than to do what you do. As I pointed out, you are THE near-perfect example. How are we going to reconcile Herb's 2016 RMAF Serious Stereo write up, with ANY and ALL that you misrepresent to HFV FMs here. ??

I say, hearing is believing !!! You have never heard my builds. ZERO experience. What did LLiu so intelligently describe to us all this past month, about hearing my SN#2 6005 SE SINGLE amp after three weeks on his speaker system this last month??? Post #38, 12-11-22 in this thread.

The " PFA TRIPLE 6005 "..... DIY tube amplifier of 2022.

05-28-2022................... A Conceptual PRIMER , On SE Tube Amplifier Power Supply Design The power supplies shown in this and last year's 6005 amp build, each have what is called " L.S.E.S." passive power supplies. This is an acronym standing for " Low Stored Energy Supplies ". In both...

www.hifivision.com

Jeff Medwin

 

[drlowmu]

PSUDING - NOT Bread-Boarding - the new 6005 TRIPLE CIRCUIT

I have intently spent the last two days at my desk, doing many PSUD power supply iterations, to design the new DC TRIPLE 6005 as I wanted it to be. PSUD software is good enough so as to eliminate the need to bread board the Directly Coupled amp, and I can proceed with all my designing without soldered resistor substitutions to obtain desired voltages.

In a DC amp, all the tube's operation points are related to all the other tubes in the circuit, and if you change ONE resistor value, to some degree, everything in the circuit's operation changes !!!!

How to design a DC amplifier circuit?

Well, you start with defining precisely how you want the first tube, the Input / Driver tube to operate, in terms of it's plate voltage, and current draw. One uses tube graphs to determine an ideal operating point. This is a critical decision. In a two-tube Direct Coupled circuit, the Input tube has the highest gain, often by several fold, thus ALL aspects of its operation are critical - to the amp's overall performance.

An example of a Driver's tube operating point might be expressed as “ 10 mA. of current draw with 180 VDC on the tube's plate, at idle ”.

Next, we address the Output tubes ( aka Finals Tubes) circuit operating points, so many Milliamperes ( current ) at some target voltage. Output / Finals tube operating voltages are typically expressed as “ Plate of the tube - to the Cathode of the tube”. Or as, Plate to Cathode Voltage “ across ” the tube, or simply denoted P-K .

An example of a Output / Finals tube operating point ( 6005 ) might be : “30 mA. at 225 VDC P-K .”

From accessible published tube graphs, we may interpret that the Finals tube requires -15 VDC of “ tube bias ” at this desired Operating Point. This is simple now !!

The 6005 will have a VDC of 180 on the control grid ( the Driver tube's desired plate @ 180 VDC ) and it will require 15 volts more, or 195 VDC , to be sought on the Final's Cathode, to obtain -15 VDC of self-bias at the control grid ( G1 ) .

Realize, this is a TRIPLE 6005, so we are dealing with 30 mA. times three, or 90 mA. TOTAL output tube stage current draw.

Use Ohm's law : 195 VDC divided by 0.090 A. provides us with a triple 6005 Cathode Resistor Value of 2,166.66 Ohms. Select a “standard” power resistor value of 2,200 Ohms, close enough, ...... only about a 1.5% difference. Rk = 2.2K.

The entire DC amp “ rests ” upon this Final's Rk resistor. It dissipates ( Ohms Law ) 0.090 A. times 195 VDC or 17.55 Watts !!!!! , continuously. I use four times over rated resistors, so a 100 Watt Rated ARCOL HS ( a pulse-designed wirewound chassis Power Resistor ) will be an smart, reliable choice. It sounds good BTW !!

What do we want to “ see ” as the 6005's PLATE VDC ?? We know this has to be 195 VDC ( Ek ) plus 225 VDC ( P-K ) , or 420 VDC on the plates ( Ea ) . Another precise VDC design goal, nailed down. Ea = 420.

We are close to defining it all. What about the Input/Driver tube's Plate and Cathode Resistor values.??

As a rule of thumb, twice the plate's voltage ( 180 VDC ) should be the B+ voltage that feeds the Input Tube. 180 VDC times two is 360 VDC B+, feeding the Input stage.

We can refine the Input tubes 360 VDC value, to FIT existing standard Plate Resistor values ? For sonic reasons, I may choose doubled-up and matched to 0.1% Roederstein Resista MK-8 resistors, available from Michael Percy. Ohms Law, 180 VDC drop at 10m mA. is 18K , the value for “Ra” of the Input tube. But two in parallel, requires use of a 36 K Ohm pair. What ohmic value is available, in 2 Watt MK-8s ???

Percy carries a 38.3K MK-8 Roederstein Resista Resistor. Closest value. At 10 mA. of driver tube current, two 38.3Ks become a 19.15K ( Ra ). It would drop 191.5 VDC across said paralleled resistor combo. This means we simply re-adjust our precise B+ goal ( to feed the front end ), from 180 VDC Xs two or 360 VDC to 180 VDC plus 191.15 VDC , or to : 371.5 VDC sought as a PRECISE B+ , to feed the Input / Driver tube.

For the driver tube's cathode resistor, use Ohms' law, and select the highest quality resistor you can afford, and that you have personally evaluated sonically ( eg : Caddock TF-020, etc etc. )

The 6005 is a beam power tube, hence it has a separate G2 connection, which I might run at, say, 5 VDC less than the 6005's operating plate voltage. That is simple to define : from prior 420 VDC ( Ea ) minus 5 VDC is G2 VDC equals 415 VDC .

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So, in all the above, I have shown DIY HFV FMs how to design your own Directly Coupled tube amp. It is my absolute favorite amplifier circuit topology.

I spent the past two days at my desk, with PSUD, experimentally adjusting the filtering which me and my mentor might use ( double shunting and Double Dennis Fraker Final Filtering ) to get the precise voltages I would need to have, for an ideal VDC operation. I often employ the three Manufacturer's R types, as mentioned in this write up. They are some of our sonic favorites, that I depend upon to provide natural-sounding high fidelity sonics.

After a ( common to the entire amp ) dual 5U4GB - L1/C1/L2/C2 input filter, with two 6 ohm DCR chokes ( wow-wee, 12 ohms total DCR !! ) two different sets of PSUD filter designs need to be developed.

Four filter stages go to the ultra sensitive Driver tube's Ra, and four are used for the Finals tubes' ultra sensitive G2 B+ supply.

As of last night, both my final PSUD chosen B+ "quad filter " choices made me happy. I will wait a few days, and review the work all-over again, to be sure there were no errors.

I will name this amp “ The Dennis Triple – FSHS ”. He is encouraging me to build it. It has design aspects similar to what impressed Dennis immensely at a Los Angeles audio show, many years ago. It was a tiny 417A, DCed into a Eimac TL-304 four-75 Watt per section ( 300 Watt ) transmitting tube, using four 5U4GB rectifiers. Single ended. A one-time design and execution back then, by the highly-capable Mr. Craig Uthus.

Please notice, how the Eimac 304TL and the 6AQ5/6005 tubes each have symmetrically shaped ROUND plates !!

Jeff Medwin

PS, Voltages mentioned herein serve only as examples, and are NOT necessarily actual VDCs employed.

 

[LLiu]

..... what an exotic tube, VT-129 304TL ! The art of living is about compromise, I'm always prepared to compromise a little bit of refinement for POWER! Excellent descriptions of your work, as always, will follow this thread with keen interests.

 

[drlowmu]

The EIMAC 304TL was a tube that my Audio Mentor, Dennis Fraker, actually worked with as a trained / specialized electronic technician in the U.S.A. Coast Guard, during his years of service. The "T" must stand for Transmitting and the 'L" for low mu. EIMAC also made a 304TH high mu version, and also a single 75 Watt round plate tube called an EIMAC 75TL, which was popular and good sounding in audio, years ago.

All these EIMAC DHT tube designs featured symmetrical to each other, round - shaped tube internal parts. No rectangle-shaped or square-shaped tube plates with CORNERS for the electrons to bounce around in willy nilly, or should I appear learned and say asymmetrically.

Hence EIMACs ( symmetrical and round ) are generally speaking, intrinsically better sounding than a 2A3, Type 45, 300B, KT88, etc. shaped tubes. Manufacturers are hesitant to design and build audio amplifiers around EIMAC triodes because it is a single tube Manufacturer, long out-of-business, representing a dwindling and increasingly scarce tube supply.

With a 6AQ5 and it's military version, a 6005, we have a similar shaped tube internally, only it is a Tetrode / Beam Power Tube with a small 12 Watt single ROUND plate ( grid and cathode ) , and it has very closely spaced elements. Its certainly not as large as any standard 75 Watt round plate by EIMAC . Lots of these 6AQ5/6005 tubes were made and never used.

Many tube manufacturers produced these tubes, over a number of years, for various industrial end users. Sonically, because of it's internal design ( symmetry and close spacing of elements ), it puts any EL-84 tube to absolute shame when both types are optimally implemented.

In my mind, and not yet tested, I guess and think it puts the best 2A3 amps I have built to shame. These 6AQ5/6005s sound best on speakers when operated with a separate and highly stabilized G2 supply, ie : as a Pentode .....and not Triode-connected ......or U.N.L. - connected . ( U.N.L. is a " Jeffism " standing for Ultra Non Linear , instead of U.L. tube operation ). Sometimes U.L. tube operation is OK, but often it is questionable to me.

To obtain life-like realism in an audio amp, I feel it is urgent to get really good high frequency response through the amp's circuit, and all the way to the actual speaker drivers. ( Recall, the TRIO speaker wire formula adds a 14 AWG to the two 12s ) . This wide band performance is what keeps our attention, a sense of amazement, and a true sense of " you are there " where they recorded the piece. Conventional 20 hZ to 20kHZ amps are BORING for me to hear, strictly mid-fi, after hearing in my home an amp with great highs on a wide band implemented audio system.

The 417A input tube DCed to a EIMAC 304TL amp, that impressed Dennis Fraker so in Craig Uthus' display, had good highs ( and lows ) !!! Described to me as " fantastic " you-are-there multiple layering of the recorded venue.

I believe the 417A is a RF tube design, a quite tiny tube envelope with the shortest of lead lengths for superior high frequency ( RF ) response.

Well my friends, in December 2022 I changed the planned front end tube on my "6005 TRIPLE " design, from a standard audio-type tube, to a RF /Communications / industrial ( O-scope ) tube. A tiny thing built with great stability and precision of design and manufacture. Hence, this week's extensive PSUDing, to optimize operating voltages and determine resistor values needed - precisely. In a month or two, I will swap out many of my present STEREO SINGLE amp assemblies, to help DIY execute " The Dennis TRIPLE - FSHS " newest 6005 monoblocks. Kindly stay tuned.

Jeff

 

[raj12345]

Can u share the schematics of this beautiful amp ?

 

[drlowmu]

Can u share the schematics of this beautiful amp ?

No, not at this time.

Look at my previous amplifier design / DIY build threads however. There are LOTS of very clear schematics and information posted. And just yesterday in Post #59, I provided a verbal description, for interested FMs to develop their own DC SE amp in a logical, orderly way.

If you get " into it" and put forth some effort, you can PM me IF you get stuck.

You will get much more satisfaction out of it, if you do not copy circuits verbatim !! Try to learn, understand them.

Jeff