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71.0.213.17
Mounted 20 A. IEC, two A.C. switches, thermistor, and Silicone II attached all four VISHAY DC LINK caps. I wired ( with 12 AWG, yellow ) L1/C1/L2/C2 for each channel. Used 10 AWG copper with silver wire ( blue ), to execute a neat star ground. Made a 10 AWG bare wire buss bar, extending either side of star ground. Fun to do.Jeff Medwin
Edits: 12/28/14Follow Ups:
Seriously, that is some beautiful work. Ah, life of a retiree, maybe one day......
Edits: 01/02/15
Jeff,
I see that you have connected the two pins together in the DC link caps. Are these caps capable of Kelvin connection as recommended by Morgan Jones? Other manufacturers of 4 pole caps mention that separating the in and out current paths, reduces mains borne noise etc. This means using the first set of pins for input from rectifier and another set to supply the audio circuits. Any experience in this regard?
Cheers!
Quoting SY over at DiyAudio,
"In terms of electrical connections, this is outlined in great detail in Valve Amplifiers, 4th edition. Basically, it's a Kelvin connection, one set of leads go to the supply, another set go to the load- they connect right at the cap foils, reducing the effect of ESR from the leads on coupling of ripple and signal between stages. "
How much effect will the ESR of the leads have on the "coupling of ripple and signal between stages"?
To me, this sounds like a solution looking for a problem.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
None, does it apply to these VISHAYS, or, are the extra pins for PC Board stability ???
I don't know. Thanks for your post.
Jeff
Work of art Jeff. Looks very nice!
I'm excited for you on this build!!
You could have saved yourself a load of wiring by placing those 4 polycaps together a lot closer to the 2A3 . I also notice that you have bridged the internal cap connections . I'm not 100% sure about this but these may be separate for a reason , such as forming a kelvin connection which reduces ESR . These are intended for high current pulse operation after all
Al
You may be right Al but, I think 4 pins is just used for PC board mounting stability. See this diagram on the Vishay tech sheet:
I'm not saying that applies to the VISHAY DC LINK caps but I would guess it does.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
If I did it the way you suggest, I'd need longer choke leads.
I am also allowing room between chokes and caps, so their fields do not interact with each other. Notice I also put a 90 degree orientation turn of L1 to L2, on each side of the chassis. The fold in the 12 gauge steel also helps, less radiation of the iron into the top plate !!
Stereo chassis, such as this one, are a mess, fraught with wiring and layout compromises. Monoblocks are so much better IF you know how to properly lay it out.
Jeff Medwin
Longer choke leads but you are using crazy-thick wire and you'll lose a lot of other wire in the process . For low noise the 0V bus would follow signal . I would star each set of PSU caps and bus to the next star . You'll keep the ripple current of the first caps further upstream . Just a thought :)
Al
Nice work. Why not "better" terminal strips?
Thanks. I tried.Certain electronic parts I just really "like" building with.
I don't think any different terminal strips would make an electronic or audible difference, so I use these, manufactured by Cinch.
I don't use them a lot, but I DO like using them here or there, neatens the build. Rats nest can be more electronically perfect, so I build a slight trade off, but wired in three-dimensions.
The seven 10 AWG to #6 ring terminals on my star ground are Thomas and Betts, I learned to use them at Dennis Fraker's suggestion, they sound "decent", and are made well.
This amp is to be for my use - going forward and LONG term, and I get to do whatever I like in there, but I gotta live with it. I "re-do" things when building, if I have the slightest doubt. For example, one yellow twisted wire pair in there, between the rectifiers, I fit and refit, shaped, NINE times 'till I was satisfied. In the end however, it makes me happy, just to LOOK at the finished piece, and know I did it.
Jeff Medwin
Edits: 12/28/14
What is your experience with on turret boards, if you have tried them? I don't need the long explanation, just your experience.
Observe, before you think. Think before you open your yap. Act on the basis of experience.
Zero.
Jeff Medwin
"The seven 10 AWG to #6 ring terminals on my star ground are Thomas and Betts, I learned to use them at Dennis Fraker's suggestion, they sound "decent", and are made well."
Dennis Fraker sounds nuts.
Yes, yes he does.
But some people think that using vacuum tubes is nuts.
Tube audio is a spectrum disorder.
I suppose some view it that way, but if asked, there are reasonable explainable engineering differences that lead people down this path.
At least that is how I got here. I did some research, tried some things out to get a feel for what are tangible changes, even if slight.
Of course anybody who has done any researching on the web has no doubt had to wade through countless threads peppered with wild proclamations based on drlomu's ears.
It is frustrating to an amateur (His target audience), to try and sort out who has the good information, it creates a lot of confusion and wastes a lot of time.
So while it may seem harsh, it's not very kind to play games with people who want to learn either.
It's all marketing, and I do agree that if he has so much to contributed maybe they should have a forum for his clergy. Like a subforum in ISO or tweaks etc.
Although realistically I don't think his builds are a good example if just for the fact of gluing capacitors and not using grommets etc.
He should have some beginners teach him how to build and amp.
Silicone has very good holding power to glass, due to molecular compatibility, It's the "Sil" in Silica and Silicone.
That does not however make it a universal adhesive. Most would tell you that they have experienced silicone coming off of other materials after some time. Some materials you can instantly peel the silicone off.
Be assured that there has been no checking into the compatibility to the silicone, powder coat and the Vishay caps Dennis invented.
I doubt he even sanded the surfaces.
In a recent preaching, he specified using GE II silicone, I would imagine because it sounds best.
So I would like to proclaim that gluing of capacitors is very poor practice.
Sure it could be done, but you've got to be sure it will hold, perhaps polyurethanes, epoxies etc would be more suitable.
A few people have commented on "rats-nest" wiring, and gluing-in of capacitors.I have found, through experimentation, listening, and measuring hum & ripple VS overall transparency in amps, that where ground points are located VS other components in an amp are critical.
As many here know, I use as little capacitances and reactances in an amp power supply as I can comfortably get away with, and you're likely to find these components mounted in odd places all-over the amp..
This isn't rocket science-- a battle has been raging for decades over whether a vacuum tube cathode should be bypassed or not, and if so, how much bypassing can be gotten away with before the capacitors literally devour all of the music, since even the world's best caps are electronic garbage-- they're non-linear filters and energy traps.
So are inductors, and that is why I try to minimize their values and maximize their energy pass-through capabilities. People have commented on load VS measured distortions in vacuum tube loading. TRE has commented-- and he has reason to do so.
It has been noted that lighter loading allows vacuum tubes to produce less overall distortion-- up to a point. It has been noted that a 2.5K load on a 2A3 tube, for instance, produces more measured distortions than a 5K load, etc.
With resistors, this is certainly true, and is why I like large resistances for plate resistors-- to allow good voltage swing without having to heavily-drive the resistor and to obtain lighter loading on the tube.
Inductors are not resistors. They have iron and many turns of wire in them. They are also (like capacitors)-- at best-- they're non-linear filters and energy-wasting traps.
Upping the turns-ratio in an output transformer-- if all else is equal-- greatly lessens the quality of that device. While it will load the output tube less, and the tube will show better distortion figures, it will also trap-out more musical information because of its increased turns-ratio, and usually-- with smaller diameter primary wire-- the smaller this wire is, the lower the quality of the device if it has to handle tube plate current-- only up to a point for sure, but it IS a factor that must be considered. Does the 2.5K transformer outperform the 5K, all else being equal? It sure does, and it is a large factor, but in some cases, one might prefer the 5K.
Why would one guy want higher distortion figures, but enjoy better dynamics, musical flow, and immediate musical "attack" response-- not to mention greater transparency-- with the 2.5K? Well, he probably likes marching bands, good Rock bands, Country & Western, Grand Piano, Big Orchestras, etc. He can still get voices "perfect" by careful wiring and superior parts choices, and placement.
Another may prefer the 5K. Why? If he likes quiet music, devotes time to appreciating smooth renditions of voices, and simple Jazz bands, he will appreciate the more laid-back feel of all that extra wire in the output transformer primary, the transformer's increased inductance, and the blunted attacks of more lively music's transients when he does play it-- which may not be that often-- the more relaxed 5K transformer may be something he LIKES-- as long as he doesn't try to replicate the Eagles Blu-Ray-- their "farewell" in Melbourne, Australia. Someone trying to do that might load the 2A3 at 2K! Yes, the tube LOVES it....
The point here is that there are reasons for what people believe and do, and for them, they are valid.
When I look at an amplifier-- I think it should be a perfect "slave" component. What I want it to do is play anything I can throw at it perfectly-- musical taste/preference has zero influence on me.
I want it all-- everything better than ANYTHING..
That's where rat's nest wiring comes in in a big way. It's those grounds and circuit paths. In general, they're better if they're shorter, but not always. And when that occurs, you have a compromise that you have to figure out before you can proceed any further.
The question is which conductors need to be short, where are the ideal grounding points, and what compromises must be made in this "ideal" landscape, in order to accommodate minimal hum-- many of the things you do to reduce it will impact musical performance-- and NOT favorably..
Which compromises will you tolerate and which ones will you rule-out? Longer wires COST-- in many ways. They can also aid in balancing-out hum at the expense of true musical transparency. If you can't stand hum, how far are you willing to go to reduce it? If you love musical attack, transparency, dynamics, etc., how much hum will you tolerate in order to create ideal circuit paths?
If you change a grounding point by 1/4 inch, then it's YOUR design!
The Rat's Nest. WHY? It's because if you parallel capacitors (such as on a cathode bypass), all of them must ground-- and connect at their "hot" ends-- at the same exact points, NOT 1/4 inch-- or more-- away from where you started connecting those caps together.
WHERE are you going to put all of them? Well, now we're into deep chassis and 3-dimensional wiring and component placement, not neat-looking pictures, as those are only 2-dimensional, and cannot show how one can neatly separate components vertically as well as horizontally-- allowing adequate room to mount them where they belong sonically.
And that brings us to G.E. Silicone 2. A comment was made regarding gluing-in capacitors. The first thing to understand is that this need WILL arise should one decide to do 3-dimensional wiring.
All those component mounting devices-- while neatly military-looking-- are stealing a LOT of your music. I know-- I spent years in military electronics and I know what "neat" is. Unfortunately, military-style construction, while pretty, super-serviceable, and making nice on-line 2-dimensional pictures-- all things that the military-trained technician needs-- will absolutely steal-away most of your music.
You're going to need to mount critical musical components where they belong magnetically, statically, and separation-wise from wiring and other components. If you hope to do this by using a lot of hardware, it will look good and sound deficient!
G.E. Silicone 2 is the rescue. I've used this in over 250 chassis to date since 1989. NOTHING has ever come loose-- even with FEDEX and UPS.
It is important to mention 3 things here:
(1) Silicone 2 is TOXIC. It is not "vinegar" based-- it is based on a toxic, somewhat odorless solvent. Use it, and then put that chassis outside for 3 days-- let it cure. DO NOT breathe it!
(2) It just doesn't "let go"-- if you wish to remove a component glued with it, you'll have to cut it with a sharp knife.
(3) Silicone 2 should be RUBBED INTO the pores of the two surfaces you're going to join with it. (don't use your bare fingers-- toxic!) THEN, if you're mounting capacitors, etc., with it, build-up a "pad" of it for the cap (or whatever )to sit upon. Twist the component around a bit-- to make sure the glue connects well to both surfaces which are already glue-prepped... You need about 1/3 inch separation of the component, so don't squish-out the glue stack.
This method is how you can place components exactly where they belong in 3-dimensions. It won't take pretty on-line pictures, but it will allow maximum performance and fairly easy component removal, should repair become necessary.
Remember that this kind of construction can take place only in a deep chassis, but the musical rewards are a'plenty.
---Dennis---
Edits: 12/29/14
"I've used this in over 250 chassis to date since 1989".. are you trying to indicate people have purchased ~250 of your amps ?... 25yrs... 10 amp builds a year.... I call BS....
"... While it will load the output tube less, and the tube will show better distortion figures, it will also trap-out more musical information because of its increased turns-ratio..."So this "trap[ing]-out more musical information" doesn't show up as increased distortion?
In other words, I think you are saying that even though there is more measured distortion with the 2.5K load, there is less "trapping" and with a higher impedance load there is less measured distortion but more "trapping" and "trapping" isn't distortion, it's something else.
Do I have that right?
If I have that right and trapping isn't distortion then what is it?
Can you tell me, in technical terms, what this "trapping" is and how it can be measured.
Is it a frequency response issue and/or a phase thing or is this what you meant when you said that an amplifier can "delay parts of the music"?
BTW I never said that a 2.5k load was too low for a 2a3. I said that a 2.5k load was too low for your 2a3.
A 2a3 running 60ma with 250 volts across the tube would be perfectly happy with a 2.5k load.
A 2a3 running 43ma with 250 volts across the tube wants a 3.9k load.
In both instances if the "proper load" in increased a little the distortion will fall even more with a little loss in maximum power.
So when you said "It has been noted that lighter loading allows vacuum tubes to produce less overall distortion-- up to a point. It has been noted that a 2.5K load on a 2A3 tube, for instance, produces more measured distortions than a 5K load, etc." I get the impression that you don't understand there are two things going on here.
The proper load (for the operating point) is one thing. Increasing the load above the proper load is another thing all together.
Thing 1. A 3.9k load is the proper load for your 2a3 (43ma/250 volts).
Thing 2. A 5k load would lower the maximum power (which neither you nor I care about) and lower the HD at all power levels up to the (now new and lower) maximum.Thing 1. A 2.5k load is the proper load for a 2a3 run at 60ma/250 volts.
Thing 2. A 3k load would lower the maximum power and lower the HD at all power levels up to the (now new and lower) maximum power level.
Before you start thinking in terms of "lighter loading " you need to first determine the proper load for the operating point that you have chosen for the tube.
43.ma at 350 volts (which the JJ's can do) would call for a 6.2k load.
2.5k can be "lighter loading " if the operating point calls for less and 5K can be "heavier loading" if the operating point calls for more.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/29/14 12/29/14 12/29/14 12/30/14 12/30/14
Yes, the 3.9K load, in this case, would be more ideal distortion-measurement wise. It would also yield max. linearity.
I chose the 2.5K load for several reasons, but chief among them was a tighter grip on the output tube, which is audible as faster speed, and greater control of the "attack" of a musical sequence. The trade-off is higher measured distortion artifacts, which, in this case, I dealt with elsewhere in the design.
It was a design choice, not an absolute, as you're pointing out.
Happy New Year, TRE-- your discussions are getting better with each post, and I'm sure people appreciate your efforts.
---Dennis---
I submit to you that what you are hearing as "faster speed, and greater control of the "attack" of a musical sequence." is just added distortion.
HD adds high frequency content that is not part of the original input signal.
Adding high frequency content is often misinterpreted as "faster speed" so there's nothing unusual about you doing that. I run into people that do that all the time.
Humans, and human hearing, are easily fooled by such things.
It takes a trained ear and a conscious effort to stay on track and still, one can be fooled. This is where measurements can help as a reality check.
BTW "more ideal distortion-measurement wise" and " max. linearity." are one and the same.
Happy New Year!
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Good cop, bad cop. They are just tricksters trying to sell amps to unsuspecting audiophiles enamored with phony esoterica.
'So I would like to proclaim that gluing of capacitors is very poor practice.'
I use double sided foam tape with acryllic adhesive for flat/light things .
Is that bad ?
:)
Al
I'm guilty of using Velcro...I'll keep you posted as far as reliablity
Stuben
A DIYer attaching capacitors using unconventional means is somewhat assumed, along with the risk.
On the other hand a self described manufacturer asking $15,000 for some amps should maybe consider mounting the capacitors on a $2 PCB as it was they were intended to be mounted.
I suppose the argument is going to be that it sounds bad blah blah even though a simple PCB would be able to have nice wide, low impedance traces to attach to.
I think you'd have to observe it over several UPS or FEDEX package drops, and have some of it in smoker's rooms for a while. Another test is in areas where someone is working on an auto, or fuel or oils are stored.
If it's still solid, and not starting to melt or let go-- after 10 years or so, one could conclude it's OK..
Sonically, you can probably do worse.
---Dennis---
.
I was hesitant to make that proclamation as I was aware that you also glued yours.
I gave the benefit of the doubt that you chose your adhesives with consideration. You seem reasonable enough.
In the past I have experienced commercial cable stays coming loose, not to say that some other foam tapes aren't better, just don't be too surprised if it lets go one day. Heat cycling is probably the culprit quite often.
It couldn't hurt to have piece of plastic below the terminals for piece of mind.
Happy New Year.
Good advice.
---Dennis---
!
The Mind has No Firewall~ U.S. Army War College.
I suspect the GE Silicone is to deal with the microphonics of solid mounting the capacitors.
I've used epoxy quite a bit with mounting capacitors. I've found about a 50% success rate.
Lots here use "goop" and claim it works well.
I think assuming a good bond that GE Silicone 2 would be OK. I was thinking of epoxying my caps in my latest build underneath but was concerned with the rigid mounting.
I still really like oilers mounting with real brackets. The new small polys from Vishay/MKP/Panasonic are intreging though..and cheap!
He built his first RADIO station, and operated out of his home in Billings, MT. when he was 16 years old. What were we doing at that age ??
He knows more about tube audio design and how to CONSTRUCT, the sounds of parts, where and how to ground a circuit, how to intelligently trade-off opposing realities, easily, than anyone I have met. I know a LOT of good audio people, and consider them as friends. Dennis and his latest amps totally SMOKES em all.
What he knows, and can do in his head, is astounding to me.
Jeff Medwin
I smell BS here. Don't forget that broadcast engineering is my profession.
My FCC rules are a little rusty but how can a 16 yr old-minor hold a station license? What were the call letters? You know the FCC has records of station ownership since 1934 on public display.
Or was this one if those two tube AM wireless microphone kits of the 1960s?
Most likely it was not a registered station. The kids would come home after school and broadcast all over the neighborhood. What were you doing at 16?
Jeff Medwin
I was one of 4 people who started our AM high school radio station when I was 14. It was a fun school club activity.
Hell, that is better than me at that age. As I recall, I discovered sex, problem was, I was all alone when engaging.
Jeff Medwin
.
I built a tv camera. Made it color at age 17/18.
All based on the project in Radio Electronics
1974.
And no, I'm not a genius! (or at least not arrogant enough to claim that)
I think the color tv thing is fucking cool gusser!
.
Have Fun and Enjoy the Music
"Still Working the Problem"
Yeah look up the construction articlle.
Search Radio Electronics color tv camera $400.
Dennis didn't claim anything special, I did, unsolicited, of he !!!
Regards,
Jeff
The arrogance is yours!
I'm my observation Dennis is much more of a gentleman on this forum.
Yes, Dennis is an all around good guy Gusser. No doubt, the arrogance is mine, I will lay claim to it, I have no problem you calling it that way. Members "read' each and every one of us here, usually correctly !! Thank goodness.
Happy New Year .
BTW, the Japanese firm that did the new KC Symphony Hall ( Helzberg Hall ) ALSO did your hall in LA for acoustics. However, we made improvements over Walt Disney Hall, since the KC job was done later.
The Architect at Helzberg Hall was Safdie Associates, a 77 year old fellow named Moshe Safdie, an ex Israeli, based in Canada. Our stage is Alaskan Cedar, the floors where 1600 patrons sit is 2 inch thick oak, and the walls are 3/4 inch Douglas fir. The plaster ceiling is 3 inches thick. The complex ( two venues ) cost $419 million and Moshe Safdie, who enjoyed a fabulous designing career, did a wonderful job.
Genius? You cheapen the meaning of the word by linking it to Dennis Fraker. Like I said why don't you and Dennis patent and then license your findings like Gordon Rankin has done in the digital realm. Has allowed his technology to reach a much wider audience and I am not sure Gordon is a "genius". As for genius, lets leave it to people like this:
Taylor Wilson from your post-- (provided URL) says he wants to save our Seaports from nuclear catastrophe. Fukushima, anyone?
If any of us can help Taylor get this done, that would be good.....
Anybody-- could Taylor, if given enough help, find a way to negate/discharge nuclear materials that have escaped into the Sea?
(The Sea itself will negate contaminants over time-- Taylor may be looking for a faster way....).
One thing people could do is to grow one's own fruits & veggies, and use this to help facilitate repairs inside one's body to save it from nuclear-induced rapid aging. Also, meats should be cooked at the lowest practical temperatures, and the percentage of live, uncooked foods increased.
---Dennis---
Really who cares. lol.
I had a one when I was 14.
Very nice work and well thought out.
Keep posting the build as you progress.
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