Not yet. I haven't bought any "expensive" caps yet. I am obsessing over this right now. I don't want to spend $100 now and wish I spent $200 later, if you know what I mean.
If a small valve cap (.022 to .1 uF) could be at the output of second stage and a DCB1 as the output from the available Hypnotize supply, I would be dollars ahead. I am looking for a cheaper solution that sounds the best.
Rush
Try the trick I suggested then. If you can make the output cap a small cap between 2nd stage and buffer with an adjustable minus supply and DCB1 like buffer then you will be able to spend much much less. Try it conceptually with a regular cap first. And you can optimize the uF value too, before spending.
I found a drawing buried in this thread that showed a B1 cap coupled out, so I modified it.
See if this would work.
Question is where to break the ground as the supply for the B1 will also be used for my crossover or it could be from my Mesmerize which ever you think best. Now that I am thinking about it the Mesmerize is closer to the phono and may provide less chance of grounding issue.
Thanks Salas, maybe others will appreciate this exercise as well.
Rush
Attachments
Yes, that picture shows a riaa completed single supply system handing over to symmetric PSU buffer through AC coupling. It should work. You got many things in one box and me to predict best grounding is impossible, you should just try it and see if it will do best to locally break and star away or not.
V12R
Back to the V12R
I decided to use a 30kr for vref so I will need 1.15mV to get the desired 35Vout.
So if I am correct Rs = Vp/Id * (sqr(Id/Idss) - 1) than admiting I use a 8mA Idss k170 and admiting it's Vp = -0.45V, I will need a Rs = 243ohm.
If my calc is correct, I can use a 500ohm fixed resistor // 20kohm trimmer to set the voltage to 35V.
Please let me know if I am in the right direction....
PS: In reality I would not need a 20k trimmer but that is the only one I have got now.
Hi Salas
Back to the V12R
I decided to use a 30kr for vref so I will need 1.15mV to get the desired 35Vout.
So if I am correct Rs = Vp/Id * (sqr(Id/Idss) - 1) than admiting I use a 8mA Idss k170 and admiting it's Vp = -0.45V, I will need a Rs = 243ohm.
If my calc is correct, I can use a 500ohm fixed resistor // 20kohm trimmer to set the voltage to 35V.
Please let me know if I am in the right direction....
PS: In reality I would not need a 20k trimmer but that is the only one I have got now.
I hope to take my Salas RIAA build to Burning Amp! I just have to get it into a box in the next 3 weeks....
I have a small collection of good load R's so we can tweak on the spot.
I'd like to try the B1 buffer above, too. I'm coupling the Salas to a Lightspeed attenuator. It's input impedance is quite low (8-10Kohm). So any chance to save on big $$ caps is worth trying.
I have a Hypnotize board here- but IIRC the L&R grounds are tied and my Lightspeed's are not. Potential for ground loops. Ahh, if I can make the time, try it and see....
-Kent
I have a small collection of good load R's so we can tweak on the spot.
I'd like to try the B1 buffer above, too. I'm coupling the Salas to a Lightspeed attenuator. It's input impedance is quite low (8-10Kohm). So any chance to save on big $$ caps is worth trying.
I have a Hypnotize board here- but IIRC the L&R grounds are tied and my Lightspeed's are not. Potential for ground loops. Ahh, if I can make the time, try it and see....
-Kent
Find it with a trimmer first because it will deviate from theory with available Vds, warm up, your measuring accuracy, things like that.
You can combine what you got in one unity gain control box. Phono-selector switch-hypno-LSPD-output. I don't know how well that combo will drive low gain amps though. It would take a standard 28dB amp for fair dynamics. In general I think 33dB total is needed from line level to speakers output for 90dB class speakers and 20-40W amps. Tube amps are usually sensitive enough for such chains. Or a 12 to 16dB line level preamp for circa 20dB gain amps and usual direct radiating speakers.
I read it now and I liked what he says about Russian Teflon's resolution that we used many times here as frugal inter-stage solution. He also says silver in oil is all rounder as we also said yesterday. Weird what he says about the Jupiter though. Wasn't compressed when I had the chance to install it. I talk the newer harder shell guise. Subjectives....naaah, so uncontrolled, but we all got a little chef inside us it seems.
I read it now and I liked what he says about Russian Teflon's resolution that we used many times here as frugal inter-stage solution. He also says silver in oil is all rounder as we also said yesterday. Weird what he says about the Jupiter though. Wasn't compressed when I had the chance to install it. I talk the newer harder shell guise. Subjectives....naaah, so uncontrolled, but we all got a little chef inside us it seems.
I bought a couple of Mundorf .1 uF silver and oil. When they come in I will install and do the DCB1 at the output of the second stage. I will try to ground at the phono board first and go from there.
There is a thread for the metal can Russian Teflon caps where he cuts the can off and wraps them in tape and epoxies the ends. Says it makes them sound better and they get smaller.
Also on the gain front. I have 90 db speakers and an F5 with standard gain and with the DCB1 I can't max out the volume without bringing the family down on me. Even when I am by myself I can't listen that loud.
Maybe my room is small, 17 ft x 13 ft with 8 ft ceiling.
As always, thank you for your help,
Rush
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Even from phono as source? Max SPL maybe not needed but dynamics can still express fuller if system gain is spot on IMHO. Not always a priority if listening near to the transducers for some. F5T is 7dB more sensitive than normal F5 BTW.