I don't suppose you have a parts list for the DX PSU? Also, what's the size of the pcb?
Can I use NJW1302 as the output? MJL21193 is back ordered at Mouser.
I can wait if the later is preferred ....
Thanks!!
I can wait if the later is preferred ....
Thanks!!
The circuit and BOM are on Greg Erskine's website.
Greg's Web Site
The circuit board is any size you can squeeze it onto. I used 7in x 4in perfboard with point to point.
For the inductor he says 40 turns of 1mm wire (13mH). Would be a lot easier to buy a ready made one.
A Mundorf 12mH BL100 air-core inductor (1mm enameled copper) is massive 77mm x 28mm! (and expensive at £28 each)
Would it be ok to use an iron-core inductor for this?
I think that is a typo - micro Henry is the typical value of a small hand would air core inductor like this. 12mH is a huge inductor but if true - an iron core would make a lot more sense. Here is one but 20ga wire.
12mH 20 Gauge Laminated Bar Core Inductor
12mH 20 Gauge Laminated Bar Core Inductor
Output devices
hi PCHW,
Go for a output device with an Ft of 10MHz or less.
The NJW1302 is a 30 MHz transistor, the MJL21195 is better suitable.
hi PCHW,
Go for a output device with an Ft of 10MHz or less.
The NJW1302 is a 30 MHz transistor, the MJL21195 is better suitable.
I asked Carlos and all he said the value wasn't critical. But I'm sure you're right and it's a typo.
I know I can use Piersma Circlophone board without a preamp but just wondered if anyone is using a preamp or buffer with it? and If so, what are you guys using?
It doesn't need a preamp as my phone can drive it fine. However, I did try it with an Apex PX6 preamp and that sounds very good.
Here is the PX6 preamp implemented on a redacted FX8 PCB and driving a Pass ACA amp.
I have also tried it with a very simple class A JFET preamp and that worked well but has a max input signal of no more than 1.4v otherwise it clips.
http://www.diyaudio.com/forums/solid-state/289905-do-you-think-jfet-bjt-pre-amp-will-work-ok.html
Here is the PX6 preamp implemented on a redacted FX8 PCB and driving a Pass ACA amp.
I have also tried it with a very simple class A JFET preamp and that worked well but has a max input signal of no more than 1.4v otherwise it clips.
http://www.diyaudio.com/forums/solid-state/289905-do-you-think-jfet-bjt-pre-amp-will-work-ok.html
In both my builds, I just took some enameled wire and wound it around a 10R 3W resistor, worked fine and no audible difference between the in total four inductors I made. Probably would measure wildly differently, though. In short, not a critical part (as made very clear by the schematic).
The preamp boosts gain but otherwise sounds transparent. Does not add or take away from the already good performance without preamp.
I was using the Circlophone to test the functionally of the preamp. So when I very good I was referring to the preamp. The main Circlophone amp sounds excellent in both cases.
I was using the Circlophone to test the functionally of the preamp. So when I very good I was referring to the preamp. The main Circlophone amp sounds excellent in both cases.
Forgot to say that I use a Cambridge audio dacmagic that has an output impedance of 47ohm (Specs here)
Does anyone have a TINA model of the JFET Circlophone that they can share? I am getting ready to transcribe the schematic to TINA myself, but figured I would ask if anyone has done it already.
