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71.50.30.115
Operational as of 12-01-2016. Mu of 100 Driver tube. L1 is 10 Ohms and L2 is 6.1 Ohms DCR - as B+ filter series-resistances to Finals. Bare chassis is 12 gauge steel, welded corners, weighs 32.5 pounds on its own. 10, 12 and 14 AWG Military Spec wire used, sometimes in mutiples, and the direct couple, easily seen, is made of three twisted 18 AWG pure silver wires.One new experience so far : I will NEVER build a shared-channel-power-transformer amplifier again ( for my own use ) after hearing this dual-mono power supply and filter approach.
Have fun, I am.
Jeff
Edits: 12/02/16Follow Ups:
.
They are purely experimental.They are VERY low in ESR and have a VERY high peak current capability, which I THINK the DHT Finals tube "loves" to see in this L.S.E.S. circuit.
I had them, all year, in my 2016 Type 45 amp. They bypass my WIMA DC LINK main caps. The Hockey Pucks although massive, are not over 10 uF.
I use double 12 AWG ( 9 AWG ) and double 14 AWG ( 11 AWG ) to wire them up, and the larger ( discontinued) XLO copper - direct gold plated spade lugs. The cap uses a 10 mm metric bolt for an AWESOME terminal connection, and I add copper washers, to snug it down. Besides being super low in ESR, these can do PEAK currents nicely. Maybe 60 A. as I recall.
Anyway, when I took out ( disconnected ) ONLY one - the C1 bypass ( as in L1/C1/L2/C2 ) in mid 2016, on my Type 45 DC amp, I thought the dynamics on my VOTT A-7s just DIED, ( leaving only one, at C2, as a bypass).
So I now have them installed experimentally, in each dual mono filter, across C1 and C2's " main " filter caps in this 12-2016 build.
Rest assured, I will take a 13 mm wrench, and disconnect them from C1 and or C2 as a bypass, and LISTEN to ALL of that, in early 2017.
Jeff
Edits: 12/02/16 12/02/16
.
Look at photo.The Gray Hockey Puck is bypassing my main WIMA DC LINK MKP-4, a 20 uF "C1" cap. Then it goes to L2, the green-framed second choke. L2 goes to Blue Hockey Puck, which is bypassing my main WIMA DC LINK 40 uF "C2" cap, ( and there is also a round DynamiCap 4.0 bypassing each WIMA DC LINK C2 cap. )
So, my C2 is composed of (1)a WIMA DC LINK, (2) a Hockey Puck, and (3) a DynamiCap 4.0 E, easily the best sounding 4.0 "I" have EVER heard !!
Got it ?? The Hockey Pucks ( Gray and Blue ) bypass my main WIMA C1 and C2 - leading to each JJ 2A3 -40 Finals tube ( via the SE output transformer, Magnequest DS - series output transformer, red TCSS lead. )
Edits: 12/02/16
Hi Jeff,
have you ever considered the poly phase rectification scheme ?
Thomas Mayer discussed in Sound Practices - Issue 16.
With 3 times the ripple freq the AC resistance is 3 times higher for the choke and three times smaller for the capacitance when compared to a single phase supply.
This translates into 9 times the efficiency for a single LC stage & 81 times less ripple for a LCLC filter ! (verbatim)
Cheers Johno
I read the article. It seems like it was just an experiment. I assume Thomas doesn't use that any more. It employs a odd ball technique.Personally, Johno, I will never use a 10 HY high DCR choke in a DHT amp !!
My highest HY choke ( in the amp above ) are the two green ones, and they measure 1.4 HY at 6.1 Ohms. L's gotta be "about 10 Ohms", or less. I always do L1/C1/L2/C2, as my favorite and best-performing B+ topology to the Finals.
The very first thing that Mr. Robert Fulton taught me, in 1982, about DHT ( 2A3 ) amps was that they are " direct access to the music devices " , and as such, all chokes have to be 20 Ohms or less in DCR.
L1 in my amps, ala Dennis Fraker's L.S.E.S., is never L-Critical....LOL. They don't need to be !! Proven 100 times over. To HECK with old theory, what works best, is REALLY what counts the most.
Jeff
Edits: 12/02/16 12/02/16
Jeff,
what AC level of hum do you have across a 8 ohm load with inputs shorted using a DVM ?
Cheers Johno
Hi Johno,
After ten minute warm up this morning, about 11.5 to 13 mVAC , inputs shorted, at speaker terminals, using Fluke 8060A DMM. JJ 2A3-40, AC heating.
I have 515B ALTEC woofers, horn loaded in VOTTs, in a small living room.
Had to put my head IN the horn section, while standing at the speaker, to hear it.
Jeff
3mV noise from my previous 845 SET amps were loud enough to hear from 6ft away on my 100dB+ 8ohm nominal load speakers at night.
My current amps have about 0.5mV or less which quieted down my speakers at night.
Something's odd with your numbers and your speaker efficiency.
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
I have only had this amp for a couple of days, only been on five hours for listening. and so, it could be a measurement problem. I am not too worried about this at the moment, it does not seem to bother me right now, and I have other things to work on.
I will re-look this over in January. As best as I recall, I had 4 or 5 mVAC on my 45 amp, and it was audible to me in October, 2016.
I do not want to throw out the baby with the bath water. Its easy to build a DC supply for a 2A3, and get low numbers, but AC heating will typically sound better.
Jeff Medwin
I think Tre has nailed it down, His speakers present a "suck out" at or around those freq.
Jeff I think its time to get your large fultons back and build a higher power SE amplifier
Lawrence
There is something wrong with the numbers.
11.5 to 13 mVAC is going to be loud on a 515 no matter what type of box it's in.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I am quite puzzled by this. I just tested with 98dB speakers, and 12 mV ac or so as a background hum is almost intolerable to my ears. There must indeed surely be some mistake in the measurements Jeff reported. I cannot believe anyone could put up with that level of background hum in a supposedly high fidelity amplifier.Even 1 or 2 mV is still enough to be irritating, I think. There is really no excuse for having any perceptible level of hum in an amplifier. And claims that killing the hum necessarily kills the music are really just hogwash. If an amplifier needs added mains hum in order to make it sound good, then there is something fundamentally wrong with its design or implementation.
Chris
Edits: 12/04/16 12/04/16 12/05/16 12/05/16
is it a 120Hz or 60Hz?
I have 0.25mVrms @ 100Hz (in EU) on my latest 801A direct coupled amplifier ... just finished yesterday (well ... I am missing the definitive 4pin sockets actually). I love direct coupled amps
:-)
in my fathers amp I think little bit of both 60 and 120 cycle.
no direct couple for me as I am trying to preserve "dynamic transconductance" and this can only be done with plate choke/grid choke RC couple system this combined with lower power supply DCR works is what I am doing
Lawrence
Jeff, something must be off here as I can hear on my fathers less eff altec 98db watt/mtr speakers 5mv hum! and this is a few feet away.
so at 12mv it should be very loud with your higher eff horns.
what am i missing here??
Lawrence
I agree, the hum should be loud even if the 515 was in a bass reflex box (which it, kind of, is).My point is, I don't think the horn has any effect at 60Hz and very little (if any) at 120Hz.
"The A-7 horn is a 110Hz exponential with a half size mouth according to Bruce Edgar and the few FR plots I have shows it unloads at 175Hz."
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/03/16 12/03/16
drlowmu,
Thanks for posting your latest Fraker-inspired circuit.
The layout and wirings are beyond what most here have done, myself included.
I'm actually trying an L1 = L2 L input supply with the 2H/300mA/21 ohm Edcor chokes for SE 6CB5 triode stereo circuit.
2H is non-critical with the B+/current draw I am using.
The power output is about the same as a conventional SE 2A3.
Also breaking in some passive 2nd order x-overs for my Altec horns.
Great fun!
dt 667
You are absolutely correct, in that Dennis Fraker prefers to have L1 equal to L2 in his LSES supply.
So.....I am taking liberty with L1 = 480 mHY and L2 = 1.4 HY.
Both of my L1 and L2 chokes only total 16.1 Ohms of series resistances, which I really like a lot.
Thankfully, there are various choices we have today, in stock under 11 Ohm chokes, of various millihenries.
Yes, I will vary the L1 pick according to the power transformer's high voltage secondary, so as to obtain a certain desired B+ VDC at C2. The smaller the mHY, the less it acts as a choke input filter, ( so the higher the C2 VDC ) and we can BEAUTIFULLY see and apply this in one's PSUD 2 simulations.
Instead of 21 Ohm Edcors, I would suggest people try the Hammond 159Y which is 600 mHY at 11 Ohms. Its probably beefy enough to do two channels of SET 2A3 Finals filtering, and its way-cool for only one channel.
PSUD this L with your Power Transformer first, as your C2 VDC will be higher due to .6 HY versus 2 HY !! Stock Hammond choke leads can be upgraded, as we always like to do now a days, to a 14 or maybe 12 AWG Mil Spec wire.
Did you notice, all the primary leads on my Hammond P.T.s are double 12 AWG mill spec wired, ( equals 9 AWG ) grey, black and white leads.
Think about it, if we do 10 AWG in a custom power cord, why in the world would we stand for 22 AWG primary lead ins ?? Everything matters. Its fun to hear.
How do you like the listening experience with two 21 Ohm chokes, versus what you did before ?? Was it worth it to do in your opinion?
Jeff
"You are absolutely correct, in that Dennis Fraker prefers to have L1 equal to L2 in his LSES supply."
That is why my LCLCRC filter uses L1=L2.
My filter is: 2H/300mA/21 ohm -> 10uF -> 2H/300mA/21 ohm -> 50uF (to finals) -> 10k R dropper -> 20uF//200k bleeder( to driver stage).
No problems @ 100mA total current draw for SE 6CB5 stereo circuit.
DF is correct about 2 LC section (L1=L2)to finals being a great sounding filter.
dt 667
schematic?
op points?
Thanks for looking !!When I said the Type 45 ( NOS ) variety ( not the costly EML, never heard them ) had a broad mid range suck-out to my ears, I was not kidding. LOL, no one up here believed me.
The new JJ 2A3 -40 "eats" my NOS 45 amp.... for lunch.
Jeff
Edits: 12/02/16
Looks Great Jeff! now your next build should be dual mono but separate chassis this could be even better! separate ground etc..
I also stick with my observations about the 5ar4 will wipe the floor with 5u4g I have used them all!!
and you know the one to use too, try them if you can.
There are no shared grounds in this dual mono amp.As previously stated to you, my SET DHT experience with cathoded 5AR4 rectifiers, versus directly-heated 5U4GBs, conflicts, and is at-odds with what you are trying to suggest to me.
Low Mu
Edits: 12/02/16
suit yourself ..and yes if your grounds are tied to one point(star ground) they ARE tied together
more observations on this new improved dual power supply amplifier?.
Lawrence
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