Nothing fancy.
A PC-scope and a soundcard. ARTA software. Well, Victor generator for the 1kHz tests...
But anyways,
all you really need for audio is a good soundcard.
Something with 192kHz sampling rate at 24bits. Asus has one, for example, and so on...
Final schematic and THD here.
Attachments
Make one of these Electronic Equiptment - DIY soundcard scope probe
Connect it across a 4- or 8-ohm resistor on the output of your amp. Feed your amp a nice 1KHz sinewave. Adjust the pot so that you send no more than a 1V signal to the computer input.
Plug into your computer mic input and use a FFT program like this audioTester OR This SignalScope for Mac
Online Tone Generator http://onlinetonegenerator.com/
Connect it across a 4- or 8-ohm resistor on the output of your amp. Feed your amp a nice 1KHz sinewave. Adjust the pot so that you send no more than a 1V signal to the computer input.
Plug into your computer mic input and use a FFT program like this audioTester OR This SignalScope for Mac
Online Tone Generator http://onlinetonegenerator.com/
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I have a front end board I'm making for the CSX2 that might be useful for someone wanting to prototype this circuit. Info is here:
http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-129.html#post4580241
http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-129.html#post4580241
LundahlF6 PCB
Is there any interest for a Lundahl PCB?
PCB size 250*50mm
and follows the diyAudio Store universal mounting specitication.
Symmetrical output stage. Select the side you want to use for the OPS mosfets, or why not USE BOTH SIDES for a double output stage!
Takes LL1517 or 1527 (and what not) or even the Jensen 123.
Diamond buffer, but JFET buffer also still possible.
I am aiming to bellow 10€/pc, but that will depend on the quantity as known..
Is there any interest for a Lundahl PCB?
PCB size 250*50mm
and follows the diyAudio Store universal mounting specitication.
Symmetrical output stage. Select the side you want to use for the OPS mosfets, or why not USE BOTH SIDES for a double output stage!
Takes LL1517 or 1527 (and what not) or even the Jensen 123.
Diamond buffer, but JFET buffer also still possible.
I am aiming to bellow 10€/pc, but that will depend on the quantity as known..
Is there any interest for a Lundahl PCB?
PCB size 250*50mm
and follows the diyAudio Store universal mounting specitication.
Symmetrical output stage. Select the side you want to use for the OPS mosfets, or why not USE BOTH SIDES for a double output stage!
Takes LL1517 or 1527 (and what not) or even the Jensen 123.
Diamond buffer, but JFET buffer also still possible.
I am aiming to bellow 10€/pc, but that will depend on the quantity as known..
Any chance you have a trimpot on output stage
Yes, some options to choose from.
Not possible, unfortunately. Has 4 degeneration resistors. You must play with the resistor values instead.
Uses the original F6 circuit where the capacitors are connected after the degeneration.
5U is not optimal. Use 4U.
Noted...
Yes, you are right. The 5U is pretty bad for the current F6 designs.
Unless you do some serious redrilling...
12 holes for this PCB.
I use 2.8mm drillbit. M3 stainless steel screws. Using oil and working the screw in to the hole slowly, back and forth...
Fill the hole completely with oil. Makes the job much easier. Oil forces all the dirt out.
You will get the drill chart with the PCBs.
...as always...
LOL!
Pretty low distortions from that poor layout, though?
Or what do you think?
Never buy my PCBs if you like high distortions.
Anyways,
the 5U is excellent for a F5t.
4U is perfect for all the poor F6ses,
if one wants to use a predrilled case, that is...
I like your work a lot Palstanturhin!
Just a quick question, is there any reason for using BD139/140 on the first stage of your diamond? I mean instead of say something like the BC550/60's or KSA992 or so (i.e. with more hfe)? It probably won't make a huge audible/measurable difference I guess...
Looks like you had them to hand (along with the 4k7 resistors)
Just a quick question, is there any reason for using BD139/140 on the first stage of your diamond? I mean instead of say something like the BC550/60's or KSA992 or so (i.e. with more hfe)? It probably won't make a huge audible/measurable difference I guess...
Looks like you had them to hand (along with the 4k7 resistors
)
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Thanks man!
Just a quick question, is there any reason for using BD139/140 on the first stage of your diamond? I mean instead of say something like the BC550/60's or KSA992 or so (i.e. with more hfe)? It probably won't make a huge audible/measurable difference I guess...
Looks like you had them to hand (along with the 4k7 resistors
It does make a measurable difference actually.
Audible? I doubt...
But you talked me into it now.
Now I just have to prototype that too...
Meanwhile, here is a list of the suitable Lundahls:
LL1517
LL1524
LL1585
LL7401
LL1591
LL1527 +XL
LL1570 +XL
LL1581XL
LL1528
LL1530
LL1571
LL1935
and LL1540 (I will test this one myself)
Some require removal of the extra pins before fitting...
You may want to get some transistor sockets to experiment with other popular drivers for the 2nd stage as well.....!!! Eg MJE340 and MJE15032 etc. Sorry 
I know I was the one originally suggesting the LL1540 however from your findings it may not be such a good idea as it has high winding DCR...
I know I was the one originally suggesting the LL1540 however from your findings it may not be such a good idea as it has high winding DCR...
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according to my experience with xformers , that can be just list of candidates
after thorough listening tests , of course each type demanding load/compensation optimization , list will be shorter