Dumble Bargain
Moderators: pompeiisneaks, Colossal
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
Anyone notice the larger (3A?) diode in the bias circuit? I wonder if that was done for tone? I know there has been a discussion regarding diode type (fast/soft...) having an impact on the tone.
Ian
- martin manning
- Posts: 13549
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
1 others liked this
Re: Dumble Bargain
Most people believe solid-state rectifiers sound different from vacuum, but in cases where solid state and vacuum are compared in the same amp, the difference is has been found to be minimal if anode voltage and bias setting are controlled. Differences between solid state rectifiers of the same type (or current rating in the same type) are likely to be extremely small, and in the case of push-pull output sections will tend to be cancelled in the output transformer. I don't see debate around solid state rectifiers in a quick search, other than the noise reduction potential of fast recovery diodes.
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
So if there is no impact to the tone/sound/feel of the amp, why would he have put a different diode in that position?
Ian
- martin manning
- Posts: 13549
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Dumble Bargain
Who knows? Why use a high current diode in a low current (bias supply) application? Some Hi-Fi types have claimed different brands of tube rectifiers have different sound, but I'm not aware of any such claims around high-current solid state rectifiers.
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
I would love to know. I have not heard a difference between 3A and 1A diodes but I can definitely hear a difference between standard (1N4007) and fast recovery diodes. I can also hear a difference in the resistors in the bias circuit so maybe HAD could hear/feel something with that diode. I highly doubt he would just randomly use a larger diode in that position.
I happened to be watching this and it piqued my interest:
I happened to be watching this and it piqued my interest:
Ian
- martin manning
- Posts: 13549
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Dumble Bargain
What part of the 1:32:24 was it that piqued your interest?
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
The video is disabled??ijedouglas wrote: ↑Sat Mar 19, 2022 11:42 pm I would love to know. I have not heard a difference between 3A and 1A diodes but I can definitely hear a difference between standard (1N4007) and fast recovery diodes. I can also hear a difference in the resistors in the bias circuit so maybe HAD could hear/feel something with that diode. I highly doubt he would just randomly use a larger diode in that position.
I happened to be watching this and it piqued my interest:
Dumble also used this diode STK-9010 1000V 3A in the Silver Alligator in the mains bank and 1N4007's in the bias? This is what I've found on FRED's
https://ampgarage.com/forum/viewtopic.p ... es#p408589
Tony
You do not have the required permissions to view the files attached to this post.
" The psychics on my bench is the same as Dumble'"
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
Yeah, just click on it and it will take you to YouTube.
I think the link you provided that was the discussion I was referring to. Any idea why he would use a 3A over a 1A when they are both way over spec'd for the job at hand?
Ian
Re: Dumble Bargain
NoAny idea why he would use a 3A over a 1A when they are both way over spec'd for the job at hand?
" The psychics on my bench is the same as Dumble'"
- martin manning
- Posts: 13549
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
1 others liked this
Re: Dumble Bargain
I thought you meant there was something specific about rectifiers in that YouTube that drew your attention to the bias diode.
HAD seems to have used replacement parts that were available from local electronics shops, or possibly from surplus shops. Maybe it was just something he had lying around, and he put it in that important location thinking that it would probably never fail?
Fast recovery diodes are required for high-speed operation in SMPS, typically 500-1000x higher than the 60-120Hz in a linear power supply. No reason not to use them at low frequency in pursuit of noise reduction, unless you are a volume manufacturer trying to pinch pennies. Here is a trace showing the reverse-bias switching transient: https://ampgarage.com/forum/viewtopic.p ... 6&p=187281 At low current, the reverse flow isn't visible at all at 100 Hz, very obvious at 10 kHz.
Re: Dumble Bargain
" ... FULL RIVER CAP.CO.,LTD (MIEC) was established in 1979, more than 40 years experiences in this area, we specialize in producing aluminum electronic capacitor, major products are middle and high voltage capacitor, MIEC is able to provide fast, flexible and innovative approaches to meet the needs of the market. ..." https://www.miec-cap.com/index/index.php
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
Based on the listing description, the amp was brought back to HAD after he bought it in 1988 to have the tremolo circuit installed. HAD also seemed to use the MIEC caps in later (5th gen on) amps. I don't think we should be trying to date the amp based on those MIEC caps The TVAs do seem to be original though.Max wrote: ↑Mon Mar 21, 2022 1:02 pm" ... FULL RIVER CAP.CO.,LTD (MIEC) was established in 1979, more than 40 years experiences in this area, we specialize in producing aluminum electronic capacitor, major products are middle and high voltage capacitor, MIEC is able to provide fast, flexible and innovative approaches to meet the needs of the market. ..." https://www.miec-cap.com/index/index.php
Ian
Re: Dumble Bargain
And what exactly do you mean by "original" in this context?
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Dumble Bargain
"original" would mean originally installed in the amp when it was built. Pure conjecture but a good chance don't ya think?
Ian