I’ve spoken to Kiat Low, good friend of mine, and owner/CEO of Duntech Audio. The Duntech Senators measures 90.5dB efficiency during their extensive testing. As is traditional from the earliest days when Dunlavy started Duntech, they slightly under report specs (not over). Stereophile and others, will do independent measures.
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I tried a sub with them, but I preferred the sound without the sub. They don’t really lack bass.
If you don’t miss bass (even if others might), perfect!
I also think a sub would probably harm their strengths.
Did anyone catch one of the latest Ask Paul sounds like the BHK 600’s are actually BHK 650’s! Gotta have that extra 100 watts over the M1200’s!
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Yes, I did notice that.They should make nice updates for those Aspens.
The video I saw with the aspen FR30’s looked like they were hooked up to M1200’s
Absolutely, but I don’t think it will be long before you see either Paul with the new setup in the sound room, or promotional photos with them advertised as a system. I suspect many people planning on purchasing the speakers will look to seeing what they can really do.
Hi paul
The input vaccuum tubes would be remain the same 6922 ?
In another thread (BHK 600 or Whatever) a link was posted to an Ask Paul video which he had the input board for the 600/650 sitting in front of him. He didn’t speak to the tubes but it looked like three tubes, one or two appeared to be small input tubes, probably 6922 or equivalent, the third was larger. Here’s a link to when he starts talking about the input board. At about 3:20 he gives a good view of the rear where the tubes are.
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I seem to recall at some point Paul referred to tube rectification so that may be the third tube.
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That was my first thought, but just by the size of the tube. I don’t recall Paul mentioning that, probably my bad memory. Paul was so against tubes a few years ago and now he is (potentially) using tube rectification? That would be kinda funny and ironic. We’ll learn soon enough just how the circuit differs from the “little” BHKs!
I suspect BHK is driving this, although Paul has certainly come a long way on tubes, at least in the input stage (even the M1200’s use them). I assume the tube rectifier is only for the input stage.
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From the FR 30 thread there has been some discussion regarding the BHK 600 including Paul revealing that the BHK 600 will utilize JJ EZ81 rectifiers. Reference line 111 from FR 30 in Da House:
The major differences are the addition of a vacuum tube rectifier (as opposed to the solid state versions used in the 300s), a massively bigger power supply and companion increase in output MOSFETS, construction techniques required to beef up the supply. The circuitry and biasing schemes are the same. The sound is not.
Release date has been pushing probably due to refining the design around parts availability, a guess on my part. Considering initial release was to be summer 2021, then pushed to end of year 2021, this thread lines 4, 90, 100, 123, 136, 151 and 164, I’d like to think the design is more or less locked down. Maybe final voicing with the Aspen (FR 30). Sharing details regarding the design would whet the communities appetite regarding a new product. Especially a novel concept regarding tube versus solid state rectification. As far as reducing noise associated with solid state rectifiers it does make sense, but tube rectification brings its own set of limitations. From the JJ EZ81 specification sheet the rectifier plate current is limited to 180 mA, so it is of interest as to how this is implemented in a 600 WPC at 8 ohms mono block amplifier. My guess is a novel power supply in the BHK 600 series.
I note, @vkennedy61 asked questions regarding the BHK 600, line 146 of this thread, but received no response. Hopefully PSA has progressed sufficiently on the project that the design is locked down and that they are in a position to share more fully the BHK design innovations.
The intent is to satisfy community curiosity regarding a new product, no point in pursuing release dates, or pricing at this stage.
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In general I’d agree, but aren’t we putting the cart before the horse?
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For sure, but if I had intention to purchase the 600’s and had desire to roll tubes, I might think about sourcing some ahead of time. I also like the RFT 6CA4
Jim McShane had a stash of the RFT 6CA4/EZ81 not sure if he has any remaining they were $22 when I bought two last year
Best,
-JP
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About when the 600 goes to the market? 
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Along with a great tribute to Bascom H. King on this weeks hifi podcast Darren talks about the upcoming BHK 600 amplifier.
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What’s your take away? Did he say when? Or listening impressions? I know you like listening to that podcast, but it’s a bit long winded for me. There are gems in those chats, but lots of asides that aren’t really up my alley.
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I need a TLDR!!! Or a TLDL(listen).
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