Rectifier swapping

Simply said: change out those Vishay block rectifiers(!)

I was not satisfied with my last two First Watt builds... something just wasn't right... they seemd to be more dry and uninvolving than earlier builds.

Then I saw a review and picture of Gamut D200i, which is a some $12000 unit using the same type of rectifier I had on my two first builds. The sound of the Gamut was stated as 'tube like', 'enveloping'. So I though I'd try the older rectifiers in stead of the Vishays I currently had in.

Changed the Vishay rectifiers out and put in DC Component rectifiers in (KBPC3510) ... Woohaa(!).. what a difference... incredible(!) The annoying highs were gone, the soundstage came together much better, was more structured and enveloping, the bass was more devoped and less thumping... simply put, quite a bit more engaging. Also could turn the volume much louder without the sound getting irritating... This same phenomena was valid with two different amps.

Don't know what it is with the Vishays (GBPC3502) :confused:... sounded kind of like they were not letting the current run through freely, so the amps weren't running at their full potential. Go figgure...

It's easy to try. Have a go and tell me if you don't agree... ;)
 
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Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
Recovery softness factor S=(tb/ta) is not specified on the datasheets of 35 ampere bridge rectifiers, and very likely is not tested. What you do not measure you do not control; perhaps mfr1 and mfr2 happen to accidentally make rectifiers with different recovery softness factors. If so they wouldn't even know it because they don't measure it, because their customers don't demand it.

Not saying this is THE explanation; it is merely one possible explanation. One which happens not to include psychological terminology such as "confirmation bias".

Of course the not-controlled aspect also suggests that different units from the same manufacturer (with different date codes, for example) might easily exhibit very different softness factors, so that two apparently identical units from the same mfr could color the sound differently. Wouldn't that be a tweaker's paradise: testing and sorting bridge rectifiers by ear!

In post#1 it appears that mfr1="Vishay" and mfr2="DC components". The 35A,50V bridge from mfr1 results in a less pleasing amplifier sound than the 35A,1000V bridge from mfr2.
 
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I thought the Vishay was a type 3502?

The vdrop may be spec'd the same max, but that's not to say they're the same actual.

Supply bridges are typically 2 uSec product. However, the TRR waveform can be all over the place, even within a manu's product line. The range is probably from soft, making 1/4 amp at 500 nSec to 1 ampere out to 1.999 uSec then snapping off in 10 picoseconds.. :eek:

Seriously, I've seen quite a range on standard stuff like this.

As to vendor to vendor differences, it could be TRR, junction capacitance, BVR of the dice... even die to case capacitance can be quite different due to internal construction geometry...some manu's use discrete leaded diodes internally, some use just the moly/die stack mounted horizontally..

John
 

Russellc

Member
Paid Member
2003-03-06 12:59 am
midwest
I thought the Vishay was a type 3502?

The vdrop may be spec'd the same max, but that's not to say they're the same actual.

Supply bridges are typically 2 uSec product. However, the TRR waveform can be all over the place, even within a manu's product line. The range is probably from soft, making 1/4 amp at 500 nSec to 1 ampere out to 1.999 uSec then snapping off in 10 picoseconds.. :eek:

Seriously, I've seen quite a range on standard stuff like this.

As to vendor to vendor differences, it could be TRR, junction capacitance, BVR of the dice... even die to case capacitance can be quite different due to internal construction geometry...some manu's use discrete leaded diodes internally, some use just the moly/die stack mounted horizontally..

John

I've used the 3502 rectifiers in a few builds and noticed no such hardness. I've used others, MURs and so forth, but not a big difference. I will try some of these and see if I note any difference.

Russellc
 
I've used the 3502 rectifiers in a few builds and noticed no such hardness. I've used others, MURs and so forth, but not a big difference. I will try some of these and see if I note any difference.

Russellc

Ah, don't get me wrong..I'm not speaking of things that made an audible difference to anything I've done. Just speaking about the differences in the diodes.

If it's anything at all, it's probably in the ground loops..


John
 

Russellc

Member
Paid Member
2003-03-06 12:59 am
midwest
Ah, don't get me wrong..I'm not speaking of things that made an audible difference to anything I've done. Just speaking about the differences in the diodes.

If it's anything at all, it's probably in the ground loops..


John

Say, I am finding this number in Mouser,even Amazon, but it doesn't appear to be the same manufacturer......does that make a difference? I'll keep looking for DC.

Thanks,

Russellc
 

Dennis Hui

Member
Paid Member
2002-08-27 7:19 pm
Toronto, Canada
Say, I am finding this number in Mouser,even Amazon, but it doesn't appear to be the same manufacturer......does that make a difference? I'll keep looking for DC.

Thanks,

Russellc

Hi,

I believe the part number itself is somewhat generic and is made by many
manufacturers. (KBPC3510 KBPC package, 35A, 1KV)


Cheers,
Dennis
 
Back in '81, I was a test engineer for the largest diode manufacturer on the planet, we shipped 4 million diodes per day. And surface mount didn't exist.

I also handled customer returns, I had to verify the failure noted by the customer, such as HTRB, leakage, breakdown, etc.. Once I verified some parts as failing HTRB, which was the most difficult test.. then about 6 months later, I got the exact same batch from another customer, failing some other test. I ended up seeing those parts three times as customer rejects.

I asked the sales guys what was going on. Turns out, they have a list of customers, hardest to please at the top, with easier to please further down the list. They would go down the ladder three times max, and if the parts were rejected three times, they would collect them in a 50 gallon drum with a large plastic bag liner, and sell them to a single, bottom feeding customer. The customer would derate voltage, current, and put them in blister paks to hang on the wall. No testing.

EVEN DIODES WITH THE MARKING BAND ON THE WRONG END!!

Be wary of your vendor..

John