Best coupling caps for a bf fender circuit

[CaseyJones]

As Ken would say, "Use your ears."

I accord to this!

I'm not exactly sure what you're saying (maybe you want to run it over with a Honda?!) but I take it you agree.

You're right up to a point and you're wrong beyond that point. I don't care who you buy your parts from, it's mandatory to check each component for spec and value on the best instrumentation you can get. If you don't all your ears will tell you is that no sound at all is coming from your amp or it's making a loud buzz.

We get capacitors every day that are either wide open or dead shorted. They aren't old dead parts out of old dead amps, they're new caps fresh in the poly bag from reliable vendors.

I can do without the hassle of guesswork while chasing after an elusive fault. I'll trust my instruments to tell me my parts are good then I'll trust my ears to tell me what to do with them.

[LeftyStrat]

In my admittedly small sampling of Sozo's, my entire batch was at the lower edge of the tolerance band (5%). Whereas my sampling of Mallory's showed them to all be within 1% of the stated value.

Not sure if this has anything to do with it, but might be worth investigating.

If oxygen in copper can have an affect on sound, surely a 4% difference in capacitance must have an affect.

[novosibir]

If oxygen in copper can have an affect on sound, surely a 4% difference in capacitance must have an affect.

It's not (only) the difference of the capacitance, what makes the difference in the amp's tone! It's rather depending on some other physically parameters and maybe even some not measurable characteristics (sounds esoteric?) of the caps, what's making the difference!

Keep in mind, that we in our 'real world' don't have anything perfect! And thus also caps aren't only 'capacitances', they additional do have a certain amount of inductivity and some serial resistance. Moreover, these 'parasitic' attributes aren't frequency constant or do have any linearity - no, they change with frequency and signal level and cause a funny mixture of phase shifts, dependuing on the frequency and on the applied signal level.

Therefore it's impossible to determine the characteristics of coupling caps simply with some additional specs like i.e. 'ESR', 'leakage current', 'tangens delta', aso. Better think about a coupling cap rather like a living animal, then you'll be much closer than any physicist

And better trust your ears more by choosing caps, than any spec's sheet or laboratory equipment

Just my 2 flints

Larry

[CaseyJones]

In my admittedly small sampling of Sozo's, my entire batch was at the lower edge of the tolerance band (5%). Whereas my sampling of Mallory's showed them to all be within 1% of the stated value.

When we get a batch of caps in we grade them. We'll go through 1000 and sort them as low spec, exactly on spec and high spec. For our application high or low doesn't really matter so much as each channel in the final assembly being closely matched.

Not sure if this has anything to do with it, but might be worth investigating.

If oxygen in copper can have an affect on sound, surely a 4% difference in capacitance must have an affect.

Oxygen free copper is a material that was peddled to audiophiles as value added. I suspect that cable construction has more effect on tone than grades of material, the trick is to reduce capacitance in coaxial cables. It's one of those deals, multiple variables at play, which are the significant variables?

And better trust your ears more by choosing caps, than any spec's sheet or laboratory equipment

O.k., fine. Take them out of the bag and use them! We do in fact screen and spec ours and we do in fact get duds. I'd prefer to spend an hour clipping caps to our LCR meter rather than spending an hour scratching me arse chasing after a cap that was faulty to begin with.

[sebastian]

I hear big differences in the sound,changing coupling caps!!
I use ONLY new caps,and the differences remains.
Marshall use to put Arcotronics R60 in 2203x and newer plexy's.For example changing this caps with some better caps like Vishay Roederstein or others (Some Wima,some Cornell Dubilier ecc ecc) change the sound of the amplifier.Changing all caps in the signal path (leaving the same values,changing only the brand) the amp sound more different from the original (a bit lifeless,dull).
A economic cap like Vishay Roederstein ERO MKT1813 make a marshall sounds good and very '70 and '80 style.(Marshall use them in the HW line of amps),without spend a large amount of money in sozo ecc ecc.
Other good caps but with a different sound are Wima MKP10 and FKP3 (more scooped and dynamic feel,more modern,similar but less ice picky than Orange drops 715P).I don't like very much the sound of Cornell Dubilier PVC line,that are very dynamic,fast and clear,but a bit thin on distorted channel;strange because Soldano use them in SLO100 amps.... .
Also the electrolitycs that decouple anodic lines of preamp and the main electrolitycs change the sound in different ways....

[CaseyJones]

I hear big differences in the sound,changing coupling caps!!
I use ONLY new caps,and the differences remains.
Marshall use to put Arcotronics R60 in 2203x and newer plexy's.For example changing this caps with some better caps like Vishay Roederstein or others (Some Wima,some Cornell Dubilier ecc ecc) change the sound of the amplifier.Changing all caps in the signal path (leaving the same values,changing only the brand) the amp sound more different from the original (a bit lifeless,dull).
A economic cap like Vishay Roederstein ERO MKT1813 make a marshall sounds good and very '70 and '80 style.(Marshall use them in the HW line of amps),without spend a large amount of money in sozo ecc ecc.
Other good caps but with a different sound are Wima MKP10 and FKP3 (more scooped and dynamic feel,more modern,similar but less ice picky than Orange drops 715P).I don't like very much the sound of Cornell Dubilier PVC line,that are very dynamic,fast and clear,but a bit thin on distorted channel;strange because Soldano use them in SLO100 amps.... .
Also the electrolitycs that decouple anodic lines of preamp and the main electrolitycs change the sound in different ways....

Great. So measure them. Some brands are exactly on spec, some brands are plus 20% and never on spec, never under.

In the studio we'll split hairs between one mix and the next, it's all relative. What sounds good only sounds good until we hear something better. We measure what we can so we have a degree of repeatability.

[Analog Assassin]

I once bought a bunch of 418p's from Dan Torres to upgrade my old Marshall 2203's coupling caps, once the caps were in my sound was ruined.

Frank

I know what you mean. I put some in my super reverb and the sound became sterile. It was harsh, colder, I didn't care for it at all. I put in the yellow Mallory's and instantly the sound had depth.

[Analog Assassin]

Hey, anyone tried high-voltage polystyrene caps in the tone stack (treble)
They sound clear but smoooooth. Mica, by contrast, has a 'bite' to it.

[sebastian]

I once bought a bunch of 418p's from Dan Torres to upgrade my old Marshall 2203's coupling caps, once the caps were in my sound was ruined.

Frank

I know what you mean. I put some in my super reverb and the sound became sterile. It was harsh, colder, I didn't care for it at all. I put in the yellow Mallory's and instantly the sound had depth.

Also Mallory PVC series in marshall amps sounds bad(too much mids and few bass).PVC series sounds very well in Fender twin applications,because they have good mids.
All the Marshall that I have tweaked with new caps,sounds great with Vishay roederstein MKT1813,with Mallory 150,with Wima MKS ,with Vishay MKT1822,with some old Plessey/Arcotronics MKT 1.50 and also with Samwha MPP (standard in late '90 marshall amp as JCM600,6100,valvestate,JCM2000).Sounds bad with the standard grey arcotronics and with PVC Mallory (thin)

[Andy Le Blanc]

My favorites are jensen aluminium and oil..... what ever you choose keep
in mind that the interior of an amp will get hotter than you think....
you can can also parallel caps of differnt types to augment the sound of
the amp towards the tone your after...... the best caps for a black face are the caps that were used in a black face.....
so if you can scroung up a beater .....or a couple yard sale specials that happen to have the same vintage
youll be in a better standing than other wise...

[Trace]

If you're blueprinting a vintage amp, you have to ignore the value designations and measure every single component. The difference between 100k and 78k in some places makes much more noticeable difference than what the composition is.

I couldn’t agree more, well said.

Heck, take a pile of 250k pots and measure them some time. They will be all over the place.

This is very true. We just went through 50 dual ganged 1M alpha pots and we were only able to find 4 that metered out the same. This does take into account that only 2 read at 1M. Over the past 8-10 years quality-control and consistency in pots in general has been poor at best.

Another interesting thing to try is wire your guitar without volume or tone controls, and then use a substitution box to select the resistance from hot to ground. Find what sounds best for you and then try to find a pot closest in value (by measurement, never trust what is stamped on the outside).

Excellent point and along similar lines, try wiring your guitar with no pots at all. Granted this will not for regular playing or gigging but it offers a very cool tone for recording (yes this is stepping outside the box--ha, ha).


Have a great Tuesday evening!
Trace

[Trace]

In the studio we'll split hairs between one mix and the next, it's all relative. What sounds good only sounds good until we hear something better. We measure what we can so we have a degree of repeatability.

If you do not mind my asking, who do you work for?


Many thanks
Trace

[Trace]

I know what you mean. I put some in my super reverb and the sound became sterile. It was harsh, colder, I didn't care for it at all. I put in the yellow Mallory's and instantly the sound had depth.

What kind of Super Reverb was it IE: black face, silver face, reissue? What kind of transformers are in the amp?


Thanks
Trace

[Analog Assassin]

I know what you mean. I put some in my super reverb and the sound became sterile. It was harsh, colder, I didn't care for it at all. I put in the yellow Mallory's and instantly the sound had depth.

What kind of Super Reverb was it IE: black face, silver face, reissue? What kind of transformers are in the amp?


Thanks
Trace

It's a blackface I rescued. It had been modded and I restored it to original values. I kept the blue caps, but I changed out the large ceramics and the big brown caps. I've kept all the original caps, although some that came with the amp do not look stock.
The power transformer was stock, the output was made by Pacific.
The orange drops were the 418p type, which are supposed to sound warmer than the 715 type. Switching to the mallorys seemed to give it a warmer, rounder sound, richer with more depth.

[Trace]

It's a blackface I rescued. It had been modded and I restored it to original values. I kept the blue caps, but I changed out the large ceramics and the big brown caps. I've kept all the original caps, although some that came with the amp do not look stock.
The power transformer was stock, the output was made by Pacific.
The orange drops were the 418p type, which are supposed to sound warmer than the 715 type. Switching to the mallorys seemed to give it a warmer, rounder sound, richer with more depth.

The reason I had asked was that in the black face era Leo used to buy from 3 different transformer companies and the results would naturally vary. We see our fair share of Fenders and we stock/use different caps depending on what the transformers sound and feel like.


Have a great Wed morning!
Trace