Capacitor test

[Darkbluemurder]

Bob, thank you very much. That sounds like a fertile area for experimentation as I have quite a few Xicons in many values.

[Darkbluemurder]

BTW: Where can you get ceramic caps in the values of 270pf to 330pf? Neither AES nor TAD nor Tubetown stocks them.

[skyboltone]

BTW: Where can you get ceramic caps in the values of 270pf to 330pf? Neither AES nor TAD nor Tubetown stocks them.

http://www.mouser.com for sprague branded ceramics. Not many values between those two though. Put them in series to net the value you want.

I like your idea of the fixed resistors for the OD trim etc. I am using some precision 1/2" cermet pots for both trimmers. These came to me surplus from a Tektronics yard sale.

I don't like the idea of my signal going through those little gizmos; at least the ones I've been able to source.

[tictac]

This is an interesting thread, I was hoping someone would bring this up.
There was alot of talk about how great the PS series caps sound. I was using the yellow polyester caps that Randall Aiken was using in my ODS, (and I liked the tone) but I ripped them all out and put in the PS orange drops hoping for even more improvement. The results I had were the tone had a harsh character, especially in OD mode.

So I decided to put polyesters back into the amp but since I had good sucess with Sozos in another amp I decided to try them. Now i've got sozo's in the preamp and 716 orange drops in the PI and the smooth, sweetness is back.

Interestingly, I was using the Blue Xicons in the PI and TS when I first built the amp and they sounded good as well. I've been using the Blue Xicons for about 12 years now and I've always liked them.

Not sure why the PS caps didn't work well in my amp. Could be a combination of a higher B+ (485V) than what most cloners are running. (although V1 & V2 voltages are in the 200V range as suggested by the forum). And I'm using Solen filter caps although I've never heard anyone say Solens make your amp brighter but I have heard comments about them taking the grainy, gritty, tone away in some Marshall style amps. personally, I like em.

These amps really are as been mentioned, a SYSTEM in which everything coutrubutes in a greater or lesser degree to the overall product; TONE.

TT

[Bob-I]

This is an interesting thread, I was hoping someone would bring this up.
There was alot of talk about how great the PS series caps sound. I was using the yellow polyester caps that Randall Aiken was using

What caps are those? I'm interested in alternatives.

(and I liked the tone) but I ripped them all out and put in the PS orange drops hoping for even more improvement. The results I had were the tone had a harsh character, especially in OD mode.

Interesting... I still have 2 PS caps in my amp and a mouser order. Once I get that I'll finish up with all xicon MPP caps.

So I decided to put polyesters back into the amp but since I had good sucess with Sozos in another amp I decided to try them. Now i've got sozo's in the preamp and 716 orange drops in the PI and the smooth, sweetness is back.

I've never tried the 716's. I found that the PI caps made a big difference so if this is smooth, it sounds like they're a good alternative.

Interestingly, I was using the Blue Xicons in the PI and TS when I first built the amp and they sounded good as well. I've been using the Blue Xicons for about 12 years now and I've always liked them.

Me too. they're small, inexpensive and sound good.

And I'm using Solen filter caps although I've never heard anyone say Solens make your amp brighter but I have heard comments about them taking the grainy, gritty, tone away in some Marshall style amps. personally, I like em.

Also interesting. Grainy is good

[tictac]

Sorry Bob I don't know how to do those quote thingys but I'll try to respond the best I can.

The yellow caps I was talking about were the ones Aiken was using. I traded a bunch of silver-plated blue teflon wire to him for a bunch of 2W metal film resistors and poly caps he was using. The caps are similar to the Mallory 150's (except a bit fatter) and probably sound similar.

The 716 series orange drops are 715's (polypropylene) with copper leads instead of steel. The polypro caps are said to be a bit more neutral sounding than polyester which is why alot of the medium grade HiFi caps are polypro as well.

I think the smoothness of the tone is due to the Sozo's, also a polyester cap like the mallorys but with a diffrent construction method. They're suposed to be a replica of the Mustard colored polyester caps used in early Vox & Marshall amps among others.

I saw some pictures of an ODS Gil had built with caps that looked similar to the Xicons except they were red. Maybe 1000V rated? Not sure exactly what they were but they were not orange drops.

TT

[glasman]

I saw some pictures of an ODS Gil had built with caps that looked similar to the Xicons except they were red. Maybe 1000V rated? Not sure exactly what they were but they were not orange drops.

TT

I think I remember Gil saying that he used PP and MPP Xicons. They are a reddish-brown in color. I think (maybe Gil will chime in) he used NTE in an amp or two but thought they were a little bright sounding.

IMO, The XICON MPP and PP or Spraque PS series are the way to go in this type of amp.


Gary

[jelle]

Hi,

I've made a list of different caps and their composition.

715P "orange drop" polypropylene/foil steel leads
716P "orange drop" polyprolylene/foil copper leads
225P "orange drop" polyester/foil steel leads
418P "orange drop" polyester/foil steel leads
PS "orange drop" polyester & paper (dual dielectric) steel leads
"Musterd caps" polyester

I've tested the 715's and I did not like it. For me it was harsh sounding, and it was lacking colour.

Then I found out that HAD used 6PS series which are polyester. At the local radio shack I found WIMA MKS caps which are metallized polyester. They are cheap and small. Now I am really happy with the sound. The WIMA, Mustard and yellow tubular caps sound very similar to me, adding colour to the sound in a similar way. But the 715 and 716 sound like a piece of wire to me. Probably great for HiFi.

Maybe the 225P and the 418P series will work good too.

The sound is as much in the schematic as in the parts and layout......

Just my two cents,
Jelle Welagen,
The Netherlands.

[Darkbluemurder]

I now replaced the 715 Orange Drops with Xicon MPPs in the overdrive channels of my modded Fenders (tone stacks and coupling caps). Both times the result was the same: the tone became noticeably clearer, less mushy in the low mids and bass and a more open sound. The amps also seem to have a quicker attack now. In the Concert this allowed me to raise the cathode cap in CL2 from 2.2uF to 2.88uF (a 2.2uF e-cap in parallel with a 0.68uF Xicon MPP) without any ill effects. Good change.
The amp still has some of the original 418 Orange drops which I will leave in for now.

In the Concert I also changed the treble cap from a 330pf silver mica to a 250pf ceramic in parallel with a 82pf polyprop. I am not sure whether I keep it. The silver mica was definitely clearer and the treble control seemed to have a bigger range.

Now I have got quite a bunch of 715 Orange Drops as replacements ...

[fabiomayo]

I'm curious, anyone tried paper-in-oil capacitors in this design?

[tonelab2]

I once pulled apart an old 0.1uF 'Mustard Cap' and discovered that they are film and foil . Aprox. 1 metre(40") of polyester and foil neatly rolled. Foil caps in general are larger than metallized caps.
Which may or may not account for a difference in tone

[keithrick]

On a whim I switched out some of the PS series for MPP and I noticed an improvement in tone as well.

Thanks for the thread Bob. I had the same harshness in the OD channel you mentioned that I was able to reduce with the Xicon MPP's. I had tried everything including treble bleed, tubes and manipulating voltages on VI and V2 and come to find out I am just not a PS cap guy!