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Post by kepa1 on Oct 8, 2008 19:59:43 GMT
Hi all, First, I hope this post is not irrelevant. Well, I upgraded my XPre quite a long time ago including swapping the 1n4007 diodes to byw 98 200. These REALLY improved the sound but are quite bigger and I had to put them under the PCB, enlarging the existing holes. Now and then resoldering them is needed because there is very small contact with the traces; unless I get buzz in the speakers. So the idea is to put the much smaller UF4007 instead, which might be a downgrade but anyway... If anyone has them in stock I'd buy 5 of them (can't get them in France). Trade is possible, just ask! Thank you Alain, Paris  |
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Post by PinkFloyd on Oct 9, 2008 11:31:03 GMT
Yes... I keep these  |
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Post by kepa1 on Oct 9, 2008 12:44:50 GMT
PM done to PF!  |
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Post by kepa1 on Oct 9, 2008 12:45:48 GMT
err, that smiley looks insane, doesn't it?
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Post by kepa1 on Oct 12, 2008 13:26:42 GMT
Hi guys, Though its Sunday, I hope someone can hear me; please heeeeelllpppp  |
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Deleted
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Post by Deleted on Oct 12, 2008 22:13:12 GMT
kepa1
Have you tried looking for UF4004 ? You don't need the 1,000V rating of the UF4007, and the UF4004 is faster at 50ns compared to 75nS reverse recovery time.
SandyK
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matt7941
100+
Mmmmmmm... Pork scratchings.....
Say cheese!!!!!
Posts: 215
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Post by matt7941 on Oct 13, 2008 9:26:29 GMT
Hi Alain.
If Alex is right, which lets face it he always is, I just happen to have 5 of the UF4004 diodes just hanging around in my parts box. If you PM me with your address you can have them for free.
Hear from you soon,
Cheers
Matt.
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Deleted
Deleted Member
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Post by Deleted on Oct 13, 2008 10:03:52 GMT
matt
Alain had previously installed the larger BYW98-200 diodes, which are rated at 200V, so the UF4004 will have even more leeway.
Alex
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Post by dejanm on Oct 13, 2008 13:40:33 GMT
Hi,
I have a question concerning Ultra-Fast diodes, used for rectifing purposes. The question is actually simple: why is ultra-fast diode better than the slow one ? Why for example is 50 ns better than 200 or whatever ? The point is that both values, slow and fast, are still much faster than 50 or 60 Hz demands for rectifing are.
Is this settling time, which is longer in case of ultra-fast diodes, really so audiable ?
BTW, I am also exchanging these 1N4007 with SF4007 (which are very similar to UF4007) but I am not sure whether it does make much sense ...
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robertkd
Been here a while! 
Electronics Engineer from sunny Queensland
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Post by robertkd on Oct 13, 2008 15:02:40 GMT
Is this settling time, which is longer in case of ultra-fast diodes, really so audiable ? that's an interesting question, the fast recovery devices are used in SMPS where the faster transition to "off" means less energy loss in the circuit and lower EMI noise. I wonder at improvements based on substitution in mains frequency derived circuits, whilst sure the conduction will stop faster compared to conventional devices, I guess it depends on conduction angle but in a well designed conventional PSU would this matter? |
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Deleted
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Post by Deleted on Oct 13, 2008 20:36:02 GMT
RobertKD One way to find out for yourself for only $4. Grab 4 x UF4004 next time you are in a Jaycar store and fit them in the PSU PCB for the SC HA.  Alex dejanm As Robert says, it is the lower EMI noise. They are even more effective in Switchmode PSUs because of the much higher voltage levels involved. My Oppo DV981HD CD/DVD-A/SACD player was quite noticeably improved after fitting the BYV26C (30nS) in the HV section. Alex |
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Post by kepa1 on Oct 14, 2008 8:45:21 GMT
Thank you Matt for your kind offer, I just PMed you. And let me tell you again that the BYW 98 200 upgrade I did was a really convincing one, much better (and cheaper) than replacing the wall plug by a toroid transformer. I'll try to report possible changes after the UF4004 are installed. |
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Post by dejanm on Oct 14, 2008 12:59:55 GMT
RobertKD One way to find out for yourself for only $4. Grab 4 x UF4004 next time you are in a Jaycar store and fit them in the PSU PCB for the SC HA. Alex dejanm As Robert says, it is the lower EMI noise. They are even more effective in Switchmode PSUs because of the much higher voltage levels involved. My Oppo DV981HD CD/DVD-A/SACD player was quite noticeably improved after fitting the BYV26C (30nS) in the HV section. Alex SandyK, You probably meant this: www.powerint.com/community/papers-circuit-ideas-puzzlers/circuit-ideas/careful-rectifier-diode-choice-simplifies-and-This snap is really an issue .... |
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Post by kepa1 on Oct 20, 2008 9:43:55 GMT
Hello Matt,
I confirm the reception of the pack; thank you very much for your kind help. I'll report the results as soon as possible.
Alain
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matt7941
100+
Mmmmmmm... Pork scratchings.....
Say cheese!!!!!
Posts: 215
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Post by matt7941 on Oct 20, 2008 11:12:57 GMT
Alain
No need to thank me I just hope you enjoy the results. Good to hear that you received them ok.
Take care.
Matt
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Post by kepa1 on Nov 5, 2008 15:07:39 GMT
Hi there,
Just a quick note to let you know that I had trouble getting rid of the BYW diodes and putting the UFs. In fact most of the PCB tracks are damaged and I had to do some hard wire soldering. Unfortunately, the only sound at the preamp outputs is shhhhhhhh. As soon as I have more time, i'll try to complete the work.
Thanx again to you all
Alain
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Post by kepa1 on Nov 9, 2008 18:03:05 GMT
Thank you. Now, this is what happens when you have two left hands (I need to double check that soon!) :  |
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