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In Reply to: RE: LOL, Didn't last long, under two months posted by deathtube 667 on January 16, 2017 at 14:57:18
DF helps me a lot!!!
re: a 7B4, a very nice, transparent tube, but I am using a different driver, experimentally to me, but precisely sounding as DF suggested it would, and it is doing just fine.
Recall the experimental " Hockey Puck " caps in my 12-2016 amp ? The experimental use will continue in the 2017 build, and DF has not yet gotten the time to evaluate that quite yet. I use them experimentally in my 800 HZ VOTT A7-800 12 dB DIY speaker crossovers also.
Jeff
Follow Ups:
Jeff -
you helped design a great power transformer with heyboer. they were able to add 2.5V center tapped filament to the secondary for me... they're actually nicely priced for such a robust massive transformer.
I think the design could be revisited with sony6060s idea of using M6 and shrinking the monster down.
in my opinion you got some of these things right "the first time", the heyboer power transformer being one of them.
those hammond 159ZA are great chokes BTW - I've had them as the first element after the rectifiers with over 80mA and no buzzing.
"those hammond 159ZA are great chokes BTW - I've had them as the first element after the rectifiers with over 80mA and no buzzing."
Rage,
How did you use that 159ZA choke?
Can I assume it was a flywheel filter and not LSES (L1=L2)?
dt 667
no it wasn't flywheel, although I experimented with that then also.
seems like I Was using the 159 as input choke, followed by 50uf, then a triad c40x, then 50uf, then another triad c40x...
it worked well... around that time jeff started telling us that 3 LCs was bad so I started reducing.
my recollection is that with 80mA and a KT120 in an SE amp that "LSES" wasn't clean enough.
my current main rig is l-critical choke input class A push pull... with ~ 700uF of film caps... big heavy choke, too much capacitance, wrong wire in single runs, constant current sinks, cree diodes, the jeff anti-thesis... ;)
have to build both sides to compare after all!
The NICE thing is, Rage and I do different things, but we remain trusted friends. We respect each other. One huge advantage I have is I get to spend about three days every year in Denver, RMAF, listening to, sometimes even exhibiting, Dennis Fraker's set up.
This year Dennis got a rave review from Herb Reichert / Stereophile, as one of Herb's two most favorite rooms to visit and hear, among 100s of rooms at the Show.
Guess what guys, in Denver - 2016, we were all listening to LSES, ( L1 = L2) chokes measuring LESS THAN the Hammond 159ZA is speced, both in HY and DCR / Ohms, and no caps over 50 uF. Sorta cool for me to know ( below the deck ) what I am hearing, experience the combo on differing program material, and HEAR how it can perform.
Since the show, DF tells me he has gone BEYOND that pair of amps he demoed, from his recent telephone descriptions to me. Much Fun !
Have a great day. My upcoming JJ 2A3-40 monoblocks will be using custom Partridge output transformers, tiny things, with a primary DCR of only 35 Ohms !!! versus the Magnequest DS-050's 360 Ohms of primary DCR. THAT change, with the LSES supply, should truly be nice to listen to.
'Next up, need to source Midnight Blue Wrinkle Powder Coat. EZ.
Jeff
I've thought about your new driver tube Jeff and I like it quite a bit.
Still laugh that Douglas suggested it ~ 4 years ago? Kind of funny how these things come full circle sometimes.
I'm going mono blocks with you... looking forward to having my DC2a3 up and running again..
There is something to be said for the ultra simplicity of the circuit. I came to appreciate it more after building a handful of push pull amps.
I really enjoy both PP and SE, particularly the direct coupled SE stuff.
I added a C40X LC section to the end of a flywheel filter and it seemed to buck down the ripple at C2 lower than C3 for some reasons.
Jeff told me that 2 LC section to finals were best as per DF, but we use other finals than JJ 2A3-40's.
Always a challenge to get a good balance of operating parameters.
What final tubes do you use, and at what current, and what is the filter's total current / and accurate supply schematic of your amp??
JM
look at jeffs original documents where he quotes jlh and pasternik (spelling) - triad c56u and two triad c40x is great budget low dcr supply. I thought the flywheel c56u worked better with more current across it as well.
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