This one’s in the books. Thanks for the outstanding build guide and support throughout this thread. Won’t be able to render an opinion on sound until I build my F5 (next project) but a quick listen on some computer monitors sounded great. Biased at ~9-12mv DC offset on each channel. I’ll drive myself crazy trying to get it any closer to zero than that.
Regulated PSU is a generic 317/337. Transformer is the Antek AS-0520. 24/-24 into the amp board.
Stepped attenuator is a 10K sold by Allo. Because I was building in a Pesante 3U, C3 size wasn’t an issue. I decided to try out these giant Obbligatos, which I thought would be fun at ~$12 a pop. JFETs are LS Matched BL from the DIY Audio Store. Switches are the ones that 6L6 used in this build guide. I only need one set of inputs for this project, but I have the option of adding some more this way.
Regulated PSU is a generic 317/337. Transformer is the Antek AS-0520. 24/-24 into the amp board.
Stepped attenuator is a 10K sold by Allo. Because I was building in a Pesante 3U, C3 size wasn’t an issue. I decided to try out these giant Obbligatos, which I thought would be fun at ~$12 a pop. JFETs are LS Matched BL from the DIY Audio Store. Switches are the ones that 6L6 used in this build guide. I only need one set of inputs for this project, but I have the option of adding some more this way.
Attachments
Look thisCoupling Capacitor Calculator by V-Cap
Interesting, using an F5 with an input impedance of 100,000 ohms the calculator says I need an output cap at .8uf.
8uF vs 10uF vs 12uF won't make any difference.
And yes, you can also use something around 1uF, but then you're limited to amplifiers with 100K (and above) input impedance.
In a low voltage situation like this, you can find every opinion on what type of capacitor should be used, from electrolytic to hand-wound angel-wing gossamer with stardust. That said, if you're going for something around 10uF then there's little reason not to use a film of some type (polyester or polypropylene), and if you're going for 1uF, then there's little reason not to use a polypropylene film.
And yes, you can also use something around 1uF, but then you're limited to amplifiers with 100K (and above) input impedance.
In a low voltage situation like this, you can find every opinion on what type of capacitor should be used, from electrolytic to hand-wound angel-wing gossamer with stardust. That said, if you're going for something around 10uF then there's little reason not to use a film of some type (polyester or polypropylene), and if you're going for 1uF, then there's little reason not to use a polypropylene film.
There is quite a selection on Parts Express starting at $1.81. The best V-Cap is $364 each for 2
. I wonder where you start to get diminishing returns
There is quite a selection on Parts Express starting at $1.81. The best V-Cap is $364 each for 2
The best V-Cap is $364 each for 2
Well, i buy Audyn Q4 series
Wow - I'm genuinely impressed at the HP engineer so may years ago who designed that PSU to gracefully operate whilst being hooked up inside-out like that. (I have one of those, BTW, they are awesome...
)Please attach your green wire to the INSIDE + and -, take your output from the outside + and -, and attach your ground wire to either of those inside posts with the green wire. Leave both of the posts marked GND alone, as you already are doing.
I'm a skeptic. That being said, I have collected all the parts to do a shoot-out between Jantzen Cross Cap, Mundorf EVO Oil, Mundorf Supreme and Jantzen AlumenZ. My best guess is that I'll have a hard time telling the difference between them, but I remain open to being wrong....
(That test will be run in a cross-over for a tweeter in a 2-way speaker. I'd be even more skeptical that I could tell the difference between those when used as a coupling cap.)
(As another data-point, the Pass HPA-1 gets rave reviews for use as a pre-amp. It uses an Elna SILMAC electrolytic bypassed with a non-audio-grade MKP to couple its output, and another non-audio-grade MKP at its input. Just saying....)
My BA3 preamp uses 10uf silmicII caps at the output.. When I use polypropylene or polyester cap, sound became disturbing at high frequencies...
No. Whenever I use bypass caps at some point, it makes component to sound worse.. Subjective point of view.. I don't have any measurement or data to support my claim ofc.
Heh, yeah I tried bypassing various projects over the years, including the BA-3, always sounds the same: like $%it. False "air and detail". Overly bright. I use to always buy botique caps, now I just buy these: incredibly low ESR: Very transparent product.
940C6W3P3K-F Cornell Dubilier - CDE | Mouser
I dont work for CDE or Mouser
So, please skip the flaming.Cheers,
Greg
Heh, yeah I tried bypassing various projects over the years, including the BA-3, always sounds the same: like $%it. False "air and detail". Overly bright. I use to always buy botique caps, now I just buy these: incredibly low ESR: Very transparent product.
940C6W3P3K-F Cornell Dubilier - CDE | Mouser
I dont work for CDE or Mouser
Cheers,
Greg
+1 on the CDE polypropylene. I used these in a recent recap of my Audio Research / Dynaco ST-70-C3 with excellent results.
