PSA - Mainly UK. KoT diodes

[SillyOctpuss]

For my PedalPCB brethren in the UK Bitsbox have got some Panasonic Ma859s in stock which they're selling for £0.46 each at the moment. Obviously expensive for a silicon diode but an absolute bargain compared to the prices being charged for Ma858 these days.

I bought a few in my last order to check them out and spent last night shooting out MA856 (I have a few left from the last batch I bought a LONG time ago), MA858, Ma859, BA282 and some regular 1n4148s.

Genuinely couldn't hear a difference at all in any of the three panasonics. The BA282 were near as makes no difference though seemed little cleaner/clearer and the panasonics seem a little more compressed/fuzzier round the edges.

The 1n4148s were definitely quieter and meant cranking the volume and tone a bit to balance them out then there wasn't a whole lot of difference tbh.

My personal favs out of last nights testing were the BA282s so that's what I currently have in my KoT build.

I'm going to do some recording where I'll reamp a dry guitar track to remove the variable of trying to play the same thing each time for each diode to see if I can hear any difference across different gain ranges.
If anyone is building a KoT at the minute and wants some diodes in the right FV range then the ma859 from bitsbox and ba282s from smallbear are definitely the cheapest way to do it at the minute.

 

[Cybercow]

In my testing of MA856 diodes, I found that the 1N4001 and 1N914 do the same job as the MA856 - as indicated in the attached curve-trace study.

 

[SillyOctpuss]

In my testing of MA856 diodes, I found that the 1N4001 and 1N914 do the same job as the MA856 - as indicated in the attached curve-trace study.

View attachment 14269

That doesn't make any sense the FV of MA856 is considerably higher than 1n914 and 1n4001. They should be reading around 790mv at 1ma. You have them plotted just over 600 at 1ma. Do you still have the MA856 you tested?

 

[Cybercow]

That doesn't make any sense the FV of MA856 is considerably higher than 1n914 and 1n4001. They should be reading around 790mv at 1ma. You have them plotted just over 600 at 1ma. Do you still have the MA856 you tested?

Whether it makes sense or not, when looking at the datasheets for all three of those diodes (MA856, 1N914, 1N4001) the Fvd is 1V. To do the curve-trace tests and plots, I used a Peak Atlas DCA75 with the software supplied with that unit. I ran several tests, and on average, they are as indicated in the plot.

And yes, I still have that specific, and other, MA856 diodes.

I'm of the opinion that the folks who built the original KoT simply used what they happened to have on hand when the MA856 was readily available.

 

[SillyOctpuss]

Whether it makes sense or not, when looking at the datasheets for all three of those diodes (MA856, 1N914, 1N4001) the Fvd is 1V. To do the curve-trace tests and plots, I used a Peak Atlas DCA75 with the software supplied with that unit. I ran several tests, and on average, they are as indicated in the plot.

And yes, I still have that specific, and other, MA856 diodes.

I'm of the opinion that the folks who built the original KoT simply used what they happened to have on hand when the MA856 was readily available.

I don't disagree with your opinion on why analogman used the ma856 but it does have a higher FV than 1n914 at 1MA which your curve trace disagrees with. That's why I said it doesn't make sense. At 1ma ma856, 858 and 859 all have a FV between 0.75 and 0.8 whereas your trace has it closer to 0.6.

Where did you get your MA856 diodes? Im not trying to be confrontational I just don't understand why your curve trace is showing completely different figures than I'm used to seeing for that diode.

 

[SillyOctpuss]

This is a curve trace from FSB which shows figures which match the readings I get from ma856 and 858

 

[Cybercow]

Remember, the Fvd specification stated for diodes is typically the "MAX" value. It can actually vary from batch to batch for the same diode type. Even the 1N34A (which we all know should have a Vfd of about 0.34v) is specified at 1V for Vfd. Such component variances and tolerance ratings are why no two identically built pedals will sound "exactly" alike.

 

[SillyOctpuss]

Remember, the Fvd specification stated for diodes is typically the "MAX" value. It can actually vary from batch to batch for the same diode type. Even the 1N34A (which we all know should have a Vfd of about 0.34v) is specified at 1V for Vfd. Such component variances and tolerance ratings are why no two identically built pedals will sound "exactly" alike.

I understand there are part tolerances but still think your figures are too low for an ma856. It's closer to a 1ss133 which looks just like an ma856 but has pretty much the same fv as 1n4148 and 1N914.

 

[Cybercow]

I understand there are part tolerances but still think your figures are too low for an ma856. It's closer to a 1ss133 which looks just like an ma856 but has pretty much the same fv as 1n4148 and 1N914.

Well, they're not "my figures", they're from a Peak Atlas DCA75 trace-curve. Electronics is not an 'exact' science per se, Rather, electronics is a fickle mistress.

Here's a photo of the MA856 diodes I got . . . .

 

[SillyOctpuss]

Ma856



MA858 next to ISS133 to show the size difference between them and the lack of a mark on the cathode lead



These were disappointingly sold to me as MA856 from a trusted retailer who later admitted they were 1ss133 when I sent them some pictures and FV readings

MA858 with MA859 next to them you can still see the mark on the cathode lead and the size are the same



According to my callipers the MA series diodes are 2.1mm x 1.6mm and the 1ss133 come in at 2.7mm x 1.8. The MAs measure from around 0.75 (MA856) - 0.79 (MA858) - 0.82 (MA859) and the 1ss133 come in closer to 0.65.