If I remember Nelson’s story correctly the ESS company drug policy was “share”.
Jim has sent more kits off to the store and more are in the works. This has proven to be more popular than I expected.
It is a nice phono stage especially with the chassis from Gianluca and the communities design involvement and hard work.
Jim has sent more kits off to the store and more are in the works. This has proven to be more popular than I expected.
It is a nice phono stage especially with the chassis from Gianluca and the communities design involvement and hard work.
For all lovers of the Cascode, I dare to repeat what I have already said: use GR, dont use BL Grade. You could also try a tiny bit: R2=12.7kOhm and R3=8.2kOhm ... otherwise you may well question the function of Q5 and replace it with a wire bridge. Apart from that, the imponderables with the four favorite jFet are natural.
Please pay no further attention
😉.
Please pay no further attention
😉.
I used an octet of 2SK170s with a matched IDSS of 7.4 mA...how would I know if this is a problem? I also put matched ZTX851s in both the Q5 and Q8 position because I had them, and as that was the original design.
Whenever Q5 is approaching saturation - but as we know, it does so very, very late. However, it should remain operational and do so quietly with a VCE >>1.2V.
The reason I dared to use 2SK170 BL was because Wayne also did that. Like Wayne I have also 9V across R1 and I use ZTX851 both places and 12 mA in total. If Q5 is saturated or not I did not measure as I did not know it could be a problem. The BL's I used was measured to about 7 mA Idss.
In all these cases Q5 is saturated and possibly already reverse biased - now you can desolder this transistor with a clear conscience and replace it with a wire bridge.
I recommend building the kit exactly as Wayne Colburn designed it, using his exact circuit schematic and his exact component values.
Listen to your pure Wayne-P3 for several weeks. Then, if you still have a powerful urge to tinker with the circuit topology or parts choices, go right ahead. You'll know how the Wayne-P3 sounds, you'll know exactly what you love about it and exactly what you think can be improved. Make your modifications and listen again; has the sound changed? Do you still love what you used to love about Wayne-P3? Did the changes improve what you used not to like about Wayne-P3?
It's quite probable you'll enjoy the Wayne-P3 so much that you cannot tolerate the idea of taking it out of your music system for a few days. So you'll abandon any thoughts of modifications, especially when you consider that (a) after the changes the sound might get worse instead of better; and (b) perhaps you might break something when making the changes.
Listen to your pure Wayne-P3 for several weeks. Then, if you still have a powerful urge to tinker with the circuit topology or parts choices, go right ahead. You'll know how the Wayne-P3 sounds, you'll know exactly what you love about it and exactly what you think can be improved. Make your modifications and listen again; has the sound changed? Do you still love what you used to love about Wayne-P3? Did the changes improve what you used not to like about Wayne-P3?
It's quite probable you'll enjoy the Wayne-P3 so much that you cannot tolerate the idea of taking it out of your music system for a few days. So you'll abandon any thoughts of modifications, especially when you consider that (a) after the changes the sound might get worse instead of better; and (b) perhaps you might break something when making the changes.
The pure "Wayne design" is using 2SK170BL and 2 x ZTX851 ?
The pure "kit design" is using 2SK209GR and 1 x ZTX851 and 1 x ZTX457 ?
Which of these are "most Wayne"? ....both?
The pure "kit design" is using 2SK209GR and 1 x ZTX851 and 1 x ZTX457 ?
Which of these are "most Wayne"? ....both?
I didn't know that was tinkering, although I was fearful of frying the 2K209s as I had never done surface mount soldering before. And I had the 2SK170s from John LaGrou, which I thought were appropriate for the circuit.
Even though I am working from home, I had to pull off the cover and measure the voltage across R1...an unfluctuating 8.5VDC. 11 mA.
Even though I am working from home, I had to pull off the cover and measure the voltage across R1...an unfluctuating 8.5VDC. 11 mA.
In MEPERs and my defense, the schematic in post #1 also has 2SK170s and uses two ZTX851 in each channel.
Wayne has "approved" using the 2SK170BL several times and I also think that when P3 was born it was the intention to have 2SK170 in the kit (but not 100% sure about that but from memory I think Wayne wrote that.....maybe search back in this thread to confirm). Reason that there are not 2 x ZTX851 in kit is because they were difficult to get.
I think you should not do anything at this point other than enjoy the sound of P3.
But interesting to learn a bit more about the cascode circuit.
I think you should not do anything at this point other than enjoy the sound of P3.
But interesting to learn a bit more about the cascode circuit.
If this is the last time you will ever build a phono preamp and you have the engineering skills to redesign the circuit, then go ahead and create/build your ultimate project. If you want to build an excellent-sounding phono preamp now/soon, and can accept that the circuit works with a wide range of devices as initially shown by Wayne, then build the kit as supplied.
Personally, I have never seen anything that was the "best", "ultimate", "final" audio design. Have fun building this, and be confident it will sound wonderful. You can always make changes later.
Personally, I have never seen anything that was the "best", "ultimate", "final" audio design. Have fun building this, and be confident it will sound wonderful. You can always make changes later.
Certainly that advice will help other people; I built what I thought was the circuit as designed. The question is, is there any reason to change what I have already built? And how to test it to see if there is a problem?