Pair of 10ohm chokes in Seduction Power Supply - beneficial?

[HF9]

Would a pair of 10ohm chokes in the Seduction power supply be beneficial at all? Something like a pair of TRIAD Magnetics C40X?

[Grainger49]

This is a good idea.  I think that the resistors in the Seduction power supply are 1000 ohm resistors.  So the replacement should be something like the Hammond 155J which folks used in the old FP 2.  The 155J has a DCR of something like 1025 ohms.

[HF9]

Thanks Grainger,

I had wrongfully assumed the two 10 ohm wirewound resistors hiding under the caps in the circle below were the ones to be replaced. Perhaps someone could confirm

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv213%2Fhighflyin9%2FDIY%2FSed-Circle.jpg&hash=e55e8d7d9757db9a240a72cbde0c98697987e13a)

[Doc B.]

Correct, those 10 ohm resistors are not the ones to replace. They are part of a reverse recovery spike filter along with the two film caps, that block the reverse recovery spike of the UF4007 rectifiers. The 1K dropping resistors between the + terminals of the filter caps are the ones to consider for replacement with the 155J or other choke with a 1K ohm DCR.

[Grainger49]

Look between T25 and T15 or T15 and T12.  You will find the resistors of the CRCRC smoothing filter.  The ones you are looking at are before the rectifiers.  They are a bit beefier. IIRC because they are on the AC side of it all.

Dan, are you saying to replace the last resistor with a choke?  That is what I have done in some builds, and have seen some other opinions.  I think PJ says to replace the first resistor with a choke.  (I am not trying to start a fight with the brains of Bottlehead here, just asking)  

I had used the logic that the component nearest the audio circuit was more important.

[Doc B.]

I'd put it in place of the first resistor. It would be educational to model it in both positions in PSUD

[HF9]

Thanks gentlemen. Now comes the choice of whether to mount them on the bottom of the plate with standoffs or the top of the plate after some sanding, painting and leather wrapping

[Grainger49]

You might try Paul Joppa's excellent suggestion about using a scope and a choke to verify which position (physical position for mounting the choke{s}) would have the least inductive coupling.  I don't know which thread it was in.

[ssssly]

Why not just replace them both?

[mchurch]

I am a newcomer I just finished my Seduction Build and I found this topic of interest. I just finished adding two chokes using Hammond 155J. There is a difference in the sound performance for the better to my ears. I can't actually describe it but it is better. I mounted them like the PT-1 on stand-offs. It was a very easy and economical tweak. If I keep at this I will run out of space. I am going to listen and let it break in a bit and then I will adding some different caps in some points to see the effect.

As I side note, the performance of this Pre-amp far exceeds my expectations and allows me to try many things without buying a new pre every time. I previously used a Conrad Johnson preamp with a phone stage and Seduction far outclasses it in the detail and low noise floor. My next project will be the extended foreplay followed by two pairs of Paramounts.

Mike