Diode Upgrades

[themystical]

Has anybody tried any diode upgrades with the X-Cans. There seems to be a bit about on the net regarding schottky's and ultrafast slow recovery ones and just wondered if anybody had any experience?

[kepa1]

Hello,

First post here so congrats to the forum owner!

I'm Alain from Paris, France and the proud owner of an X-Pre (similar design to X-10D) since the early 90's. I gradually modded it including caps, trafo, etc.

I did the diodes upgrade on the X-Pre and this was a real improvement too. I'd say it is as important as replacing PS caps. I chose BYW98-200 diodes which have a strong reputation as far as audio is concerned and bypassed them with 103 ceramic caps just for the fun of it!

I strongly encourage you do the same. 1N4007 diodes are general purpose and their strong Amp rating is not relevant here. Besides, BYW98 or other rectifier diodes are pretty cheap.

Just be sure to respect polarity and to manage the little size of the PCB holes : you may enlarge them with a driller or solder diodes on the surface of it, or consider diodes with little legs.

As for me, I was wondering how to post in this forum, I couldn't find the right place (?).

I'm about to change the 10µF polar caps near the tubes (C105 on the PCB) as it seems to be a critical component. Black gate should be the best alternative.

I'm also interested in replacing the actual X-Pre pot with the bigger Rk27 ALPS pot, I think someone did it before, including making a large hole of the X-ponent panel

[rickcr42]

There seems to be a bit about on the net regarding schottky's and ultrafast slow recovery ones and just wondered if anybody had any experience?

check your pc board pad spacing before ordering shottkeys to make sure they will fit !

Most come in a TO package (and with TWO rectifiers inside)





and SMD




and the normal IN400X style rectifier casing.

[imghttp://www.opamp-electronics.com/~opamp/catalog/images/1N5817_1A[/img]

hell all kinds of packaging



really sucks to accidently order the wrong part,something everyone who does DIY work has done at least once

higher voltage ratings are usually best in replacement parts and especially so in a DC rectifier that gets stressed out every time you turn the power switch to "on" (filter caps are a dead short at turn on).

You also need to consider the difference between the RMS and peak operating voltage + headroom so it is always best to go for the highest voltage rating that will fit the pcb or you will need to make a daughter board for the new rectifiers

[themystical]

Thanks for the response Alain/Rick. The BYW98's are listed as "fast" recifiers on the RS website which also has an "ultrafast" category and their is laso the issue of the recovery characteristic .... fast or slow. Sonically what was the improvement you got Alain and have you tried out any other diode types??

[kepa1]

As said above, improvment is REAL, better dynamics and image is what I'd say.

BYW are a good choice but there may be others (I just didn't compare). Just be sure to chose radial types and why not do a comparison yourself? Theses are pretty cheap.

Here is how I fixed them on the PCB:



Alain

[sometrolls2]

Would you advise going throughout both boards with replacements, as with caps?

Both the BYW98 and ultra fast cost little, so there is a large low cost choice, what should I look for as the key values?

[rickcr42]

I mostly go with vacuum tube rectification (even sounds good with solid state,see Stefano Perrigini DAC Glass Audio magazine article digilander.libero.it/paeng/a_24_bit_audio_dac.htm ) because there are ZERO ultrasonic harmonics unlike silicon rectifiers-a real plus with digital audio that has problems in this area already but silicon rectifiers do/can/may have an apparent tighter bass than a VT so is used often with tube gear.

When I DO go with silicon I have used the UF Series for years preceeded by a Johm Camille/Buddah/Bottlehead snubber.

[PinkFloyd]

MF use the 1N4007 why not try the UF4007 (ultra fast variants of the 1N4007) easy to get hold of, cheap, and they'll fit spec sheet here www.vishay.com/docs/88755/uf4001.pdf

[rickcr42]

original snubber

diyparadise.com/ps_snubber.gif

www.cognitivevent.com/images/fp_snubber.jpg

V2

www.audioasylum.com/forums/bottlehead/messages/106676.html

[rickcr42]

www.siteswithstyle.com/voltsecond/foreplay_filament_snubber/Foreplay_filament_snubber.html

[PinkFloyd]

May well try the 10R resistor too at some point.