Just a sneak peek of the discrete front end to go into my HGF once I get them hauled back up to Skunkworx and disassembled. Nothing wrong with the onboard solution, but I just like to try stuff.. Those sticky-up adapter cards are loaded with Tantalum Nitride 1206 SMD's by TT Electronics. Passive's don't matter dum dum! (I know, but there it is..) Mark Levinson ad copy touts these things in critical spots (Levinson? never heard of 'em..) So the rest of it is quad K170's with zener referenced cascode on the input, bootstrapped VAS (flying rails), onboard RC rail filtering w/low ESR caps, 12db (4X) gain, blah, blah.. If it's crap EZ enough to switch back..
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I have had the amp cooking for a few 8 hour runs, heatsinks get warm but not toasty, bias at 1.5A, offset solid at a few mV. I did have a nasty experience the first time I hooked it up. I had been given a balanced dac for the test rig and initial offset was 8V DC, I shut it down and started to look what I could have done with final wiring to mess things up and something made me check the dac output (yes, I should have checked it before using it but it came from a trusted source and was said to be working), the dac output is seriously borked, luckily no obvious damage to the amp. Set up with my normal trusted SE source and it sounds amazing in the test rig. Plan to move it into my main system and let it sing for a while.
Thanks for a great project and look forward to playing with all the possibilities with this design.. dB
Thanks for a great project and look forward to playing with all the possibilities with this design.. dB
cranked through a few favourite test tracks and am suitably impressed - easily holds its own against my reference build - fully balanced 50W class A (M2OPS) which I have found does the best job of driving the maggies out of all the amps I have built thus far ( M2X, F4, SissySIT, Aleph 30, LuDef, XRKs 100W A/B, Baby Huey-PP EL84 )
It plays plenty loud but I keep things turned down typically for mid 60dB and spikes up to 80, really exceptional spatial separation, good heft to the bass, layering etc - all the things you look for in high end audio technicalities. I had this FW clone chassis from an amp that was damaged in shipping a friend had bought. I added the momentary switch for the soft start circuit.
this amp will remain in the system
..dB
It plays plenty loud but I keep things turned down typically for mid 60dB and spikes up to 80, really exceptional spatial separation, good heft to the bass, layering etc - all the things you look for in high end audio technicalities. I had this FW clone chassis from an amp that was damaged in shipping a friend had bought. I added the momentary switch for the soft start circuit.
this amp will remain in the system
..dB
They are 4ohm, 86dB/500Hz /2.83v
https://magnepan.com/collections/floor-standing/products/magnepan-7
So not the easiest load but the HG doesn't seem to mind them at all.
https://magnepan.com/collections/floor-standing/products/magnepan-7
So not the easiest load but the HG doesn't seem to mind them at all.
But they are literally like a resistor to an amplifier. And phase is flat as a pancake.
See measurement of Magnepan LRS by Stereophile below:
The .7’s probably measure very similarly. All you need is an amp with some current capability and you’ve got it.
Best,
Anand.
This is one of the things that has attracted me to planars for the past decade or more, and why the F4 worked so well ( my preamp just couldn't swing enough voltage - yes, I could just have built another preamp but then I would have missed out on trying some other splendid designs ) . Having built all the amps I have, this is the amp I would recommend someone to try if they were wanting to build "just one" FW styled amp ( if that is ever possible ) . That said, there are several amps that have caught my attention that I have not built, the Alpha Nirvana being one. This is what makes DIY in PASS-land so much fun ..dB
My discrete FE is not beating (subjectively) the OPA551 built into the ZD25-Mini at this time. It's certainly not "bad", but will need some further thought and a re-tool before attempting a rematch. The Holy Grail Follower is a great amp all the way around, sounds fantastic. I'm putting together some active rectifiers just to push the PS rails up a bit. Not a huge thing, just trying to squeeze all I can out of this power supply.
Correct.
The whole idea of the ground loop breaker is to that advantage of the differential inputs to the opamp to help remove ground loop noise. There is an increase in the common mode noise when both channels use the ground loop breaker, increasing the ground noise.
I will attempt to create a more complete explanation for a future posting.
Correct.
Emphasis added is mine in the quote.
Are you asking if you should place a jumper / short between the pads for those components? Maybe not, but just being sure.
There are two external alternative connections for the RCA (or XLR) ground:
- GND: Direct connection between the RCA ground and analog ground of the ZD25-Mini.
- GNDR: Ground loop breaker connection the RCA ground and analog ground of the ZD25-Mini.