New Design, SE 6005 Directly Coupled Audio Amplifier

Audiolab 6000A Integrated Amplifier

drlowmu

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Jeff, Currently confined to a small room, my current speakers are L shaped single driver OB, 8" to 12", 95dB to 100dB, measured good from 70Hz to 16-17K for the most capable ones.

I have been curious about DC and IT coupled amps, latter coz of very minimal passive components count. DC because the idea of a capacitor shaping the sonics over the tube itself is unsettling for me and defeats the actual purpose of tube amps but its a necessary evil for maximum topologies.

Mine first ever was SE Pure Class A, no NFB 6BM8 SE with option to DC but sold it to a friend before I could try the DC option. Just finished the classic Mullard EL84 PP running in Triode mode.

Been always curious on 6B4G PP and one particular build based on IT coupled. For the IT build, acquired a couple of pairs of Sansui 1000A OPTs but the Lundahls are still fleeting....

Met a person from UK who has a very peculiar cascade DC designs for tube amps but recent health issues have been weighing him down.

Sent you a PM but not sure if I have all the parts needed.

My immediate next is a very simple tube rectified F2a SE amp, for which I have all the parts.

But would certainly like to build the DC 6B4G PP some day soon. The Russian tubes are on my mind though currently there seems to be a plethora of some fine American NOS tubes selling at great prices....

Sam.


I could not find the schematic of what you are building. Can you easily PM it to me?? I see Shindo's F2a amp uses a 6AW8A input tube.

A 6AW8A seems to be a triode and pentode in one tube. If this is what the F2A amp uses as the front-end tube, to get 10 Watts, ........you are starting a build at a distinct topology disadvantage. It is too complex !!

1) It is a three stage amp. ( the extra middle stage .......loses information ).

2) It has to split the signal's phase ( and later re-combine it ).

3) It does not use all triode tubes.

I just PMed you a simple design where 1/2 a 12AX7 is DCed to the grid of a single 6B4G ( a SE amp ).

So now, we have a KISS topology. Two stage, DC coupled, SE, and all triode tubes.

In my experience, nothing can touch this, IF ( a very big word ) it is done well. ( Sadly, it is usually never done well, highly compromised ). In all cases, I am assuming the very best build, in each topology.

The SE 2A3 type amp is only 2.5 Watts. If you want to hear the best sounding amps, it is only done with proper high efficiency speakers !!

An (above) post's two stage DC P-P amp, ( 12BZ7-6B4Gs ) should easily outperform any three stage P-P amp in existence. Easily,........IF done well. Because it is two stages, and Directly Coupled.

But a two stage DC SE amp will outperform any and all P-P amps, on efficient speakers. There...... you have it.

I should say, this is all " IME" and "IMHO". Were you able to follow my logic Sam?? Less is more, when done properly. Best wishes to all.

Jeff

PS: As for " DC VS Interstage Coupled ", DC wins, hands down. Re read J.C. Morrison, a bit earlier in this thread. He agrees.
 
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yogibear

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It’s a Klangfilm KL 204 clone with single EF12 at driver stage, UU5 tube rectifier. Very simple.

Have Monoblocks, with one channel had a transit damage hence decided to build a single channel first from a scratch. Don't like to see the amp sitting duck. Hence will try to make my first P2P ever. Minimal parts, SE tube rectified. It does make 10 wpc. Hopefully do next channel too if first is a success and with no issues. Have all spare parts.

Shindos is a PP. I will be replicating the SE. One F2a tube, one EF12 and UU5 rectifier, each channel. Have the ladder ones, UU5. Its a sight to behold, when the UU5 fires up.

My lowest is 1.5 wpc SE Tube 45. Drives my speakers to pretty high loudness under half of the volume. SE 6BM8 was just 2 wpc.

Tube mania has no limits...... Want to indulge in affordable tubes which don't cost more than the amp itself !

Have 95dB to 99dB speakers so they mate well. Did a mistake of selling the 100dB and 101dB drivers in past.... Telefunken Open baffle would have driven them to glory.....
 

drlowmu

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Yogibear writes :


My lowest is 1.5 wpc SE Tube 45. Drives my speakers to pretty high loudness under half of the volume. SE 6BM8 was just 2 wpc.

Tube mania has no limits...... Want to indulge in affordable tubes which don't cost more than the amp itself !

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

Yogibear :

Tube enthusiast friends of mine will invariably call me, and ask me to design for them a two stage DC SE Type 45 amp. ( As though the Type 45 is the best output tube in audio .) I always dissuade them .

I explain, how in 2015-2017, I wasted TWO YEARS of my audio life, designing and building two DC DIY 45 amps.

My DIY designs ridiculously outperformed a friend's Yamomoto A-08 45 amp, embarassingly so - to the Yamomoto. But my DIY 45 SE DC amps' could not play full-range linearly, no matter how good was my circuit. The fault was never remotely in the circuit, but it was because of a design flaw in any Globe or ST Type 45 tube itself !!!!!!!! It simply flunks - playing the bottom end of a grand piano properly, the lower registers.

So Yogibear, this entire 6005 thread is my 2021 answer, to the shortcomings I easily heard, and do not accept at all, in the often-hyped Type 45 tube !!

To replace the ST 45, a ten dollar NOS 1950's 6005 TETRODE, ( which does play linearly, and has several other endearing qualities ) is used. 99 % of the audio world today that I survey, is unaware - has never heard - of what the 6005 tube can do, when optimized. It is superior in it's more modern tube design and construction than any vintage ST Type 45. It plays linearly !! The 45 can not. This will be much FUN - to build, to own, and to hear. Lead, and not follow.

Triodes like a 6B4G, and many 2A3s, can play a grand piano properly also.

Can you P.M. to me a schematic with some VDCs of the Klangfilm KL 204 clone?? Thanks !

Jeff
 
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yogibear

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I will share the Klangfilm schematic. My tube 45 SE beats Yamamoto as well. It has been reviewed well by others too.

I have EL34 SE, Tube 45 SE, 6AS7G PSE, EL84 PP UL, EL84 PP Triode, F2a SE, 6BM8 SE (third pending build), many half finished Class A SS with tube stage (pending PS builds…) I hope I have not missed any…

A few others I have not ever played but stored elsewhere and few more builds pending with all parts sourced, sorted out.

I cannot critically compare all until I finish my speakers and play them in a
larger planned room.

6005 will be soon some day too…We have a saying “until you die, you don’t know what’s dying”. So be it !!!

Here, Klangfilm schematic:

 
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drlowmu

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Yogibear :

Thanks very much for showing us the Klangfilm schematic. Interesting. 'Appreciated.

You probably know "exactly" how I would critique it :


" It is too complex, has too many un-needed parts in series with the signal path, which lose information."

Which parts to eliminate ?? That is easy :

a) The series " grid stoppers "
b) the two series coupling caps
c) the middle stage.

Jeff
 
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yogibear

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Yogibear :

Thanks very much for showing us the Klangfilm schematic. Interesting. 'Appreciated.

You probably know "exactly" how I would critique it :


" It is too complex, has too many un-needed parts in series with the signal path, which lose information."

Which parts to eliminate ?? That is easy :

a) The series " grid stoppers "
b) the two series coupling caps
c) the middle stage.

Jeff
Already trimmed and simplified. Each channel has now hardly 10 components total. PS is CLCRC and tube rectified.
 

drlowmu

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I have a lot of film caps and associated parts to add to this stereo amplifier build, so I must build "UP" in three dimensions, and not just lay out the amp in two dimensions, as most builders do.

Today I designed a simple "build module", which will allow for many parts to be positioned, in the vertical axis. It only takes one bolt to attach the module to the all-steel 14 gauge chassis. Uses Keystone 817s and a Keystone 1567.

012.JPG 004.JPG 011.JPG 009.JPG

Very simple construction.

Jeff
 

drlowmu

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09-13-2021 MINI UPDATE

Today was spent carefully building eight of the newly- designed " VAM"s or "Vertical Attachment Modules". A dozen parts, including 9 high quality film caps, are to be attached onto each module .

These eight VAMs will be used in two stereo amps.

005 (2).JPG



A single VAM feeds cleaned-up B+, to each channel's Input tube...powering the plate's resistor ( Ra, or R anode ).

A second set of VAMs will feed greatly cleaned-up B+ to each channel's output tube " G2" grid .

A " G2" grid exists in a 6005, which is a tetrode output tube. The G2 supply, ideally, has to be the most carefully executed in the amplifier. Sadly, it almost never is. ( However, this particular 6005's G2 B+ is quadruple series passively filtered. Each channels' G2 "VAM" provides two of four passive B+ filtering stages . I have never seen this done before in audio. I briefly heard this quadruple filter in the prototype, in about 3-2021, and loved it !! ).

It is commonly said, and commonly known, " the best way to run a tetrode ( or a pentode) is with a really superb G2 supply." But in practice, everyone I see " cheaps-out " and no one does G2's B+ really well.

All the modules' nuts were securely tightened. I used Loctite brand " Threadlocker " in lieu of lockwashers. This is a removable treatment, a blue liquid, # 242 .

The next task over the coming few days is to figure out how to best position, wire, and solder each part ( nine film caps, two small one Ohm filter chokes, and in some cases - a high-quality plate resistor ) to a VAM.

Once these VAMs are fully parts-populated, one needs to figure out how they should be best positioned, ( inside a space-restricted stereo amp.)


Monoblocks are much easier to build

I hope you approve of the term " VAM", as it was just made-up when posting here today. I thought it was a good honest description - ' liked it.

Amps ideally should be laid out in all three three dimensions, not just in two dimensions as we almost always usually see. Vertical is often not fully-considered . " To VAM, or not to VAM, that is the question ". .............................Shakespeare / Hamlet

Jeff
 
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drlowmu

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09 - 14 - 2021 MINI UPDATE

008 edited.jpg
009 edited.jpg 011.jpg


Next, finish building this first first ( ever ) VAM, and neatly duplicate seven more .,........for two stereo amps. Many others solder better than I. That is OK with me. " The bigger the glob, the better the job ". ;)

Thank you - for looking. I hope some of you enjoy this build.

Jeff
 
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drlowmu

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09-17-2021 MINI UPDATE

Finished today the first of the 6005 amp's four needed Vertical Attachment Modules, or "VAM"s.. This is a unusual double series passively filtered B+ assembly.

It is designed to " clean up " the B+ at the actual point of use. It is a low DCR ( about 2 Ohms total ! ) " Final Filter ". A single module will " clean up " the B+ to the Input tube, separately, at the left and right channels. ( Always remember this : If we lose ANY music information at the Input tube stage, it NEVER will get " made up ", later-on in the amplifier ! ) .

A similar pair of modules will "clean up" the ultra sensitive tetrode " G2" connection to the Output tubes', for the left and right channels.

This " VAM " consists of a 15 uF / 900 VDC 4 pin WIMA main filter cap, followed by a small round black choke, followed by four different ( each smaller value) film caps. This completes the FIRST, of two identical passive filter sections.

A duplicate second filter section - "starting with a second black round choke, etc., cleans up" whatever the first misses - to be bullet-proof under music's dynamic conditions. The smaller the film cap value, the higher-up it plays in the music spectrum. ( Multiple film cap bypassing, this is called. ) Parts values and film cap choices are solely determined by ear.

A completed VAM module could be EE notated as : C ( =15 uF ) / L1 / C1a, C1b, C1c, C1d / L2 / C2a, C2b, C2c and C2d.

Almost all Manufacturers and DIYers will not do all this extensive "final filtering", primarily out of sheer thoughtlessness ( their self- ignorance ) and secondly, out of their own cost-containment issues and limitations.

036.JPG 025.JPG 037.JPG 031.JPG 032.JPG 047.JPG

Three more VAMs to build for this stereo amp, and another four VAMs to build for a second stereo 6005 amplifier that goes to Hong Kong. These VAMs will get bolted to the side walls of the new stereo amp chassis, to better utilize internal chassis space.

I consider these VAMs mandatory in my SE DC amps - to achieve the best attainable resolution and dynamics. This double passive filter assembly puts quality film B+ storage caps within 1 /8 th of an inch from where they are being used .......... not four to eight inches away in the chassis .......as almost everyone else in tube audio design does !!!

Notice the build, how none of the nine capacitor bodies touch each other. They are positioned such that their fields do not interact negatively with each other. The Devil is in the Details.
 
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drlowmu

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09-23-2021 MINI PHOTO UPDATE

027.JPG 028.JPG 001.JPG 019.JPG


LOL, on second look : .....( above ) ..........guess it really should have been Labeled " Ground Wires, White ".


021.JPG 024.JPG


Ran out of solid silver-content hook up wire, so the eighth module awaits more 19 AWG " Wonder Wire " arrival.

' Been busy building - the last few days. 'Happy these are finished .

MUCH MORE ..... TO DO !! Parts are on hand.

Just the thought of what these B+ filters do musically, enables ( and actually encourages ) me to " hang in there" and patiently construct them.

Eight VAMs ( Vertical Attachment Modules ) are used as part of the final filtering for two stereo 6005 SE DC amps presently under construction. These modules double- L/C- filter the B+ voltage to the Input tube's plate resistor, and another module double-filters the tetrode Output tube's internal grid ( G2 ).

Thank you - for looking.

Jeff
 
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drlowmu

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MINI UPDATE 09-24-2021

Early today, the final ( eighth ) VAM ( Vertical Attachment Module ) was completed.

I have spent time today experimenting with a new needed module, the Cathode resistor ( Rk is the E.E. term ) bypass capacitor module, ( RkM is the new term, ( while we are naming MODULES - in this amp's design. )

A cathode ( "k" is the E.E. term ) resistor ( "Rk " ) in my amplifier has added to the Rk an all-film bundle of multiple caps, five usually.

A separate " RkM " is needed for each channel's Input tube ( 6N23P ) cathode resistor and for the Output tube ( 6005 ) cathode resistor.

Here pictured below, is what I have experimentally put together
. It covers the "main" bypass cap ( 15 uF WIMA / 900 VDC / 4 Pin , a lovely sounding cap by-the-way ), and the next two smaller caps of the paralleled bunch. ( three total - of the five used ).

There now is a need to "stare" at this assembly for a day or so, and determine if there is a better way to execute the design. If not, four RkMs get built, one each in the stereo amp's four signal tubes.

In another post, I will discuss the " ins and outs " of a vacuum tube's cathode resistor, and how it can be bypassed effectively. Allow me time to show this arrangement, posted below, to my Audio Mentor - and make a final design decision.

002 edited 9-24.jpg 009  edited 9-24.jpg 003 edited  9-24.jpg 005  EDIT USE.jpg



The single-bolt chassis-mount allows for placement precisely where it is best in the chassis, and it allows for angling precisely. Good layout and chassis wiring is ultra critical for high performance, especially in a Single Ended amp.
 
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drlowmu

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09-25-2021 PROGRESS REPORT

An hour after posting, and trying to visually imagine the " experimental "RkM " bolted to the bottom of the audio chassis, lightning struck, and a solution was discovered - precisely what to do.

It is no longer " experimental ". I was so happy.

That bundle of three film caps ( 15uF, 0.68uF and 0.22uF ) was too large and it sat too low in the chassis.

The RkM's large size and lowness to the chassis, would cause it to interfere with other needed circuit wiring ( such as the filament wiring and the direct coupling wiring ), all occurring at " tube socket " pin height - estimated to be about one half inch off the chassis floor.

All that was needed was to transpose the same triple large cap assembly from the shortest Keystone Board Bracket ( #1567 ) to their tallest one ( #1569 ). Now, the entire film capacitor bundle can be positioned ABOVE existing components, and at more positions on the chassis floor, and at any angle required.

The vertical axis, nicely ............. to the rescue !


KEYSTONE 1567 ETC..JPG


A hole needs to be drilled 1.5 inches below the #1569's stock top-most bracket hole, to maintain the #1567's 1.5 inch bolt-on spacing. That is all . ( The "S" dimension in the datasheet .)

The remaining smallest two ( of five) bypass caps, ( their uF size-selected for augmentation of music's lower-highs and highest-highs ), gets soldered directly at the " point -of-use " right across the tube's cathode resistor, at the tube socket. Close to zero lead length, ..... which is electronically ideal.

Please note : conventional tube amplifier builds we see, most of the time, pay considerably less attention to the Rk and it's capacitor bypass, or, they usually find several more nasty-sounding ways to avoid the task. There is no free lunch.

We usually see a " quality " electrolytic. How can any " quality electrolytic " compete with a carefully-chosen bundle of film caps, selected by ear ???? Well, ....it can't.

Realize, the Rk bypass cap is IN THE AUDIO CIRCUIT, in a similar fashion as a series coupling cap !!

Would we use a " high quality electrolytic" as a coupling cap ? Of course not !! Never. We would instead use an expensive film cap, as good as we can afford if we sought highest performance.

However, 99.99 percent of amps one sees, uses an electrolytic Rk bypass caps, a " quality one" .... without much additional thought of how to execute the circuit better.

Parts quality in a simple two-stage directly-coupled amp, ( an amp that is being built for all-out audio performance ), is critically important. Nothing can be taken for granted, ALL is audible. Every resistor, and every run of wiring in the amp, must be selected not only to be electronically sound, and also be carefully selected by ear, for optimal sonic performance. Yes, every single inch of wire !! And the amplifier MUST also be laid out intelligently, if you want to " boggie on a world-class basis " when hearing your favorite music played back to you.

The Rk of my 6N23P Input / Driver tube does not dissipate a whole lot of power when in use. A small fraction of a Watt. This allows the use a really nice-sounding quality Rk, among the best ever manufactured. It is a Caddock TF020. Here is the write up....sounds delicious in writing, and it is awesome / lovely to hear. Would you pay $6.50 USD for a single 0.33 Watt resistor? I will .

Available from Michael Percy Audio in the USA, here is his Catalog description :

Caddock TF020  .33 Watts.JPG




...................................... Caddock TF020 photo.JPG


By the way, I would highly recommend M. Percy as a source for better parts, and I believe he ships Internationally. Decades of quality service, and a great person to deal with. Add him as one your quality parts supplier !! A+++. Download his 2-2018 catalog.

Thank you for looking and following along. This is so much fun.

Jeff
 
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yogibear

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09-17-2021 MINI UPDATE

Finished today the first of the 6005 amp's four needed Vertical Attachment Modules, or "VAM"s.. This is a unusual double series passively filtered B+ assembly.

It is designed to " clean up " the B+ at the actual point of use. It is a low DCR ( about 2 Ohms total ! ) " Final Filter ". A single module will " clean up " the B+ to the Input tube, separately, at the left and right channels. ( Always remember this : If we lose ANY music information at the Input tube stage, it NEVER will get " made up ", later-on in the amplifier ! ) .

A similar pair of modules will "clean up" the ultra sensitive tetrode " G2" connection to the Output tubes', for the left and right channels.

This " VAM " consists of a 15 uF / 900 VDC 4 pin WIMA main filter cap, followed by a small round black choke, followed by four different ( each smaller value) film caps. This completes the FIRST, of two identical passive filter sections.

A duplicate second filter section - "starting with a second black round choke, etc., cleans up" whatever the first misses - to be bullet-proof under music's dynamic conditions. The smaller the film cap value, the higher-up it plays in the music spectrum. ( Multiple film cap bypassing, this is called. ) Parts values and film cap choices are solely determined by ear.

A completed VAM module could be EE notated as : C ( =15 uF ) / L1 / C1a, C1b, C1c, C1d / L2 / C2a, C2b, C2c and C2d.

Almost all Manufacturers and DIYers will not do all this extensive "final filtering", primarily out of sheer thoughtlessness ( their self- ignorance ) and secondly, out of their own cost-containment issues and limitations.

View attachment 62055 View attachment 62056 View attachment 62057 View attachment 62058 View attachment 62059 View attachment 62060

Three more VAMs to build for this stereo amp, and another four VAMs to build for a second stereo 6005 amplifier that goes to Hong Kong. These VAMs will get bolted to the side walls of the new stereo amp chassis, to better utilize internal chassis space.

I consider these VAMs mandatory in my SE DC amps - to achieve the best attainable resolution and dynamics. This double passive filter assembly puts quality film B+ storage caps within 1 /8 th of an inch from where they are being used .......... not four to eight inches away in the chassis .......as almost everyone else in tube audio design does !!!

Notice the build, how none of the nine capacitor bodies touch each other. They are positioned such that their fields do not interact negatively with each other. The Devil is in the Details.
MINI UPDATE 09-24-2021

Early today, the final ( eighth ) VAM ( Vertical Attachment Module ) was completed.

I have spent time today experimenting with a new needed module, the Cathode resistor ( Rk is the E.E. term ) bypass capacitor module, ( RkM is the new term, ( while we are naming MODULES - in this amp's design. )

A cathode ( "k" is the E.E. term ) resistor ( "Rk " ) in my amplifier has added to the Rk an all-film bundle of multiple caps, five usually.

A separate " RkM " is needed for each channel's Input tube ( 6N23P ) cathode resistor and for the Output tube ( 6005 ) cathode resistor.

Here pictured below, is what I have experimentally put together
. It covers the "main" bypass cap ( 15 uF WIMA / 900 VDC / 4 Pin , a lovely sounding cap by-the-way ), and the next two smaller caps of the paralleled bunch. ( three total - of the five used ).

There now is a need to "stare" at this assembly for a day or so, and determine if there is a better way to execute the design. If not, four RkMs get built, one each in the stereo amp's four signal tubes.

In another post, I will discuss the " ins and outs " of a vacuum tube's cathode resistor, and how it can be bypassed effectively. Allow me time to show this arrangement, posted below, to my Audio Mentor - and make a final design decision.

View attachment 62298 View attachment 62299 View attachment 62302 View attachment 62304



The single-bolt chassis-mount allows for placement precisely where it is best in the chassis, and it allows for angling precisely. Good layout and chassis wiring is ultra critical for high performance, especially in a Single Ended amp.
Those Wima red bricks look like “candies” to me. Would not mind hoarding a few sacks of them if a deal happens !

BTW in audio signal path, how do the Wimas compare to the Russian PIO and Hybrid PIO ?

I need to do a comparison myself between a few caps, someday.
 

drlowmu

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Those Wima red bricks look like “candies” to me. Would not mind hoarding a few sacks of them if a deal happens !

BTW in audio signal path, how do the Wimas compare to the Russian PIO and Hybrid PIO ?

I need to do a comparison myself between a few caps, someday.

Yogibear,

A " deal " happens on WIMA caps, well selected ones, every single day of the year, at their retail prices !!!!

They are industrially priced, not " audiophile " priced.

They will often outperform the usual Russian surplus caps DIYers use IMHO.

When you say " audio signal path " I am not sure precisely what you mean. Are you referring to a coupling cap?? If so, I have little experience as I try to avoid coupling caps in designs whenever it is possible. Hence, direct coupling, ...... ( a few runs of Cardas 19 AWG solid silver wire, outperforms every coupling cap - and every interstage transformer, ever invented. That should be evident to people. )

In general, some Manufacturers use WIMAs as coupling caps, but I personally feel WIMAs are not good enough in that position in a circuit.

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

IMHO, every cap in a SE amp is IN the signal path, because you certainly can hear every single one of them in any position - if you build transparent quality SE amps.

Notice, I only employ film-type caps, no electrolytics.

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

I use selected WIMA DC Link film caps, as power supply caps - in most cases. I prefer to augment ( bypass ) the WIMAs powering the output stage with ultra-high peak-current industrial pulse-duty caps, capable of 1,500 Amperes PEAK Instantaneous. This large round grey-colored 5 uF bypass capacitor is called a GTO cap. It does a wonderful job. It totally defines the leading edge of music transients, which is totally missing with all other caps I know of. So much FUN to hear, really fun !!

Specifically Yogibear, to filter the output stage I use a L1/C1/L2/C2 topology, and C1 and C2 get GTO bypassed. Leave C1 or C2 UNbypassed, ( missing either GTO ), and the amp dies, is boring, .... no fun at all to hear IME.

In Rk bypass duties Yogibear, WIMAs are NOT nearly as good as Mundorf Supreme Silver and Oils, but at a mere fraction of the cost, the WIMAs can be a useful choice.

In power supply positions, certain WIMA DC LINK sizes and uF values are superior sounding - than other WIMAs !

To save people the trouble : for a 50 uF supply cap, use a DC LINK MKP4, 800 VDC rated with four pins, NOT two pins. In smaller uF sizes, the 15uF WIMA DC LINK MKP4 with a 900 VDC rating, and four pins, is THE one to use and listen to !! It is wonderful-sounding, ..... highly recommended.

COST : Mouser shows the preferred 15 uF WIMA part at $5.00 to $6.00 USD. The 50 uF part is about $16.00 USD. Previous to the discovery of this 50 uF cap, from 1989 on in SE amps, my Audio Mentor used 47uF plus 47uF high voltage Blackgate "WKZ" Electron Transfer caps, which are no longer made.

In 2021, we sell off surplus NOS stocks of 47uF + 47 uF Blackgate WKZs on eBay, for $450 to $700 each, and replace them ( happily ) with two $16.00 USD 50 uF WIMA DC LINKS. Overall, performance-wise, we prefer the WIMAs !!

So there you have it Yogibear.

Please keep in mind,

1) our amps are thoughtfully wired with silver-content Military Spec wiring, etc etc, which helps us hear things that lesser wiring obscures.

2) each amp's two chokes to the output stage totals only 12 Ohms in DCR, and

3) we use dual directly heated ( instantaneous response ! ) tube rectifiers.

Hari Iyer's mono amps, now playing in Mumbai, are similarly constructed to this standard. He seems to be happy.

Jeff
 
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yogibear

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I have two 220uf / 63 volts electrolytic caps in my current build. How do I go about substituting them with Film caps ? And those are not part of B plus PS.

I can try, compare between the two monoblocks and hear it out myself.
 

drlowmu

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Yogibear,

I don't like what you suggest.

I really don't think you can take one or two things that I discuss, and try it out successfully on an A-B basis ( to come to self-made conclusions.) Our amps are likely totally different from each other, starting with vast differences in our` basic power supply.

You use some sort of vintage UU tube rectifier, maximum rating is 125 mA. and it is indirectly heated.

Since 2019, my amps use two tube rectifiers ( directly heated - which beneficially is " instantaneous sounding " ). My rectifier tube choice is 250 mA. rated, and capable of 4.7 Amperes peak currents. ( GE 5U4GB data sheet. )

There are numerous other differences - I would surmise :

The comparative DCR of our filter choke(s) , ( my two chokes total 12 Ohms ) , the layout and wiring details ( and hence, transfer efficiency ). 1,500 A. GTO caps in the filter to the output stage. The use of cap coupling VS Direct Coupling.

An amplifier's performance is the sum total of ALL aspects that comprise it.

Subbing-in a few film caps, into a non-B+ position, possibly may be misleading and a waste of a person's time and money.

Jeff
 
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yogibear

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Jul 31, 2014
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Yes, all that I can do with the present schematic is play with some different caps at the most, since both channels need to be alike and stay put with the schematic.

It has to be a different, DC amp to learn further and hear and understand it myself.
 

drlowmu

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Oct 28, 2020
Messages
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Warrensburg, Missouri
09-27-2021 MINI PHOTO PROGRESS REPORT

The finalized / vertically - elevated " RkM " ( cathode resistor bypass modules, holding 3 of the 5 film caps ) are fully developed.

Eight "RkM"s, enough for two stereo amps were constructed, finished today. The remaining two smallest film caps, for the highest frequencies, get attached to each tube's Cathode resistor directly ( Rk ), at the tube socket. This remaining two film cap bypass is ideal - done at the point-of-use, with almost zero lead length.



003 (3).JPG 004 (3).JPG 010 (2).JPG

Am not sure if a third Keystone 817 terminal strip will be needed, but photo above shows it.

Below, eight RkMs for two stereo amps . Mirror - imaged, back row versus front row.


017 (2) EDITED.jpg
020 (2).JPG


The " VAM " and " RkM " assemblies will nicely resolve previously- experienced space and parts access problems, when employing multiple film bypass capacitors. Especially in a stereo amp chassis. These two different modules enable parts to be easily accessible and serviceable.

It is a joy to have developed these two simple "Module " solutions.

NEXT : On to determining the best tube socket orientations, and overall chassis layout. Stay tuned.

Thank you very much - for looking.



Jeff
 
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