Preferred coupling and tone capacitors for 5f6a build

[Mike_J]

I am rebuilding my 5f6a Bassman using a layout based largely on Doug's design. When I originally built the amp I used blue molded Ajax caps for all the .1uF positions. Somewhere along the way I put Blue Sozo caps in for all the .02 caps. As I mentioned in other posts I was never really satisfied with the amp as it was.


Size limitations in Doug's layout lean against anything as large as the blue caps except perhaps in limited positions. I have available the Xicon and yellow Mallory 150 series coupling caps which from a size point of view would work better. As I mentioned I have the blue Sozo caps for the .02 positions and yellow Sozo's for the .1 positions in the PI.


I am leaning towards the Xicon's for the V1 coupling caps and the .02 cap feeding the V3 grid. I have Xicon .1uF @ 250VDC caps I am going to use on the presence pot and in the PI section feeding the presence pot and resistor. What I am not sure of is the two .02 tone caps and the two .1 caps in the PI section. All things being equal it would be best to use the Xicon's or 150s in these positions because of size. However, usually all things aren't equal. Does anyone have experience with a 5f6a Bassman or early Marshall build using similar circuitry concerning the use of capacitors they consider better than others for these circuits? I need to modify the circuit board if larger caps will be used. Thank you for any suggestions you can provide.

[Mike_J]

Other .02 value caps I have found in my cap drawers are one Mullard yellow @ .18uF, many Auricap .02uF @ 600VDC, one yellow Jupiter Vintage Tone and many Astron PIO .022uF @ 400VDC. Also have Orange Drop PS series caps but they are quite large. Have read good things about the Mojo Dijons but have none of those. See Doug sells them in his store so easy enough to acquire.

[Mike_J]

Just found a pair of Xicon MPP .1uF @ 630VDC caps that some on one site liked for the PI caps. As an added benefit they fit perfectly on the Hoffman board.

[SILVERGUN]

Here's a thread that might provide you with some useful info:
Do capacitors sound different? (el34world.com)


The cap thing is a rabbit hole of epic proportions.

[sluckey]

I think Doug's boards are probably designed for use with those Xicons. M150s will also fit nicely, but those bigger caps look gaudy on a Hoffman board. I only use Xicons and M150s (trying to phase out the 150s) for all my stuff. My preference is the Xicons because of the physical size and also because they don't melt (like the 150s) if you accidently drag a soldering tip across the body.

[Mike_J]

Here's a thread that might provide you with some useful info:
Do capacitors sound different? (el34world.com)


The cap thing is a rabbit hole of epic proportions.

I read Willabe's post. Well done. I seem to live for rabbit holes. A modern day Don Quixote in search of the best windmill/capacitor.

[Mike_J]

I think Doug's boards are probably designed for use with those Xicons. M150s will also fit nicely, but those bigger caps look gaudy on a Hoffman board. I only use Xicons and M150s (trying to phase out the 150s) for all my stuff. My preference is the Xicons because of the physical size and also because they don't melt (like the 150s) if you accidently drag a soldering tip across the body.

Do you hear a tone disadvantage to using the Xicon's versus another cap?

[sluckey]

Do you hear a tone disadvantage to using the Xicon's versus another cap?

Nope. Doesn't mean you wont.

Xicons do the job and don't take up a lot of space. Very reliable too. I like designing layouts with small caps. I've never bothered to compare caps for tone differences.

[Mike_J]

Don't recall a lot of discussion concerning tone caps making a big difference on Willabe's post. The biggest differences seemed to be between polypropylene versus polyester caps as I interpreted it. The Xicon MPP caps are polypropylene if my research is correct. I am definitely sold on polypropylene for the pi section and based on the Willabe post is probably a good choice for the V1 coupling caps. Have some IC polyester caps that are the same size as the Xicon's that I could put in the tone section for comparison. I believe the yellow 150s are polyester as well as an alternative and would fit on the board as you mentioned. Wouldn't require modifying the board although I will probably throw in a couple extra turrets on the board in case I have to experiment with tone caps.


Thanks
Mike

[Mike_J]

Do you hear a tone disadvantage to using the Xicon's versus another cap?

Nope. Doesn't mean you wont.

Xicons do the job and don't take up a lot of space. Very reliable too. I like designing layouts with small caps. I've never bothered to compare caps for tone differences.

I haven't played in a band in over 40 years. If I was used to the impact the blending of a band with an amplifier has I would probably be much more practical about relatively less important tone factors than capacitors. Always looking for the magic ingredient that in the long run probably doesn't amount to a lot. There has to be something that makes that rare amp sound so good. Reality is the amp was probably recorded right before it blew up. When my daughter was young I had an amp that sounded really good. My daughter who is now a mechanical engineer was in the room with me while I was saying how great I thought it sounded. A few seconds later poof goes the tubes, smoke billowing out of the amp. Any time I said anything good about an amp after that she came running in with the fire extinguisher.

[Colas LeGrippa]

If you bother about the tone and not the space and if you have extra bucks, go for Jensen paper in oil. My prefered ones. I don t know if Doug carries them, but there are copies out there in the net with very good performance too.
Even in a guitar amp they worth extra $

[Mike_J]

If you bother about the tone and not the space and if you have extra bucks, go for Jensen paper in oil. My prefered ones. I don t know if Doug carries them, but there are copies out there in the net with very good performance too.
Even in a guitar amp they worth extra $

I have some Astron .02uF @ 400VDC CPO4A1 PIO caps that I haven't used because I am concerned they might leak DC. Would probably try these first before buying anything new. Do you have a preferred spot in the circuit for the Jensen PIOs? Also, couldn't I test for DC leakage by testing a new cap by lifting the side of the cap opposite the plate and testing it for DC voltage? Then connect the Astron to the same place and see what kind of reading I get. If the readings are similar the cap is probably good? I probably have ten or more of these and would like to know if any are useable. They aren't real large either.

[Mike_J]

Started looking into oil filled caps. It sounds like Jupiter PIOs may be becoming discontinued. On one site someone suggested Audio Note caps as a good alternative. Looking into these caps their silver foil .022uF @ 600 VDC caps are reasonably priced at US$ 214.50 each. Will never know how these caps sound. Ignorance is bliss or at least somewhat less expensive.


Decided to look at CE to see if they have any oil filled caps. Turns out they do. Their .02uF @ 600 VDC oil filled caps are polyester film and foil but not sure what kind of foil. Think I might prefer tin foil over the silver since it might be more in line with the original 59 Bassman caps. These caps sell for $2.79 each and have a nice red band to mark the outside foil. Has anyone had any experience with these MOD caps?

[Colas LeGrippa]

I paid 30 bucks for Jensen caps. To try them.
I wouldn t have paid 215 $ for a single cap.
Better off with orange drops at 2.50.
Everything is matter of good sense. I know my amps sound right , but are the Jensen caps really responsible for that ? 
I am planning to build another Lil' Gripper this week, this time with orange drops. I ll see the difference then.

[Mike_J]

If what I read is correct and they are discontinuing the Jensen PIOs you may want to stock up. I would be interested in seeing how the MOD caps compare to the Jensen's. Can't beat $2.79 per cap. They aren't paper in oil. The Dielectric is mylar/polyester not paper but they look well built.

[tubenit]

It is a VERY subjective thing regarding caps and tone.  What I've personally settled on is Orange Drop PS caps.  IF I can't get those, my second choice is Orange Drop 715 caps in the preamp to the LTPI and from LTPI on using Xicon or  Mallory's (or the equivalent).   OR my 3rd choice is a mix of Orange Drop, Xicon and Mallory caps.

with respect, Tubenit

[Colas LeGrippa]

Angela sells pio caps for cheap too.
If ever they become discontinued, I ll unwrap one and check how they are done.
I have already assembled a .022 cap with alu foil and wax paper, but too big to be used in an amp. The trick is to wrap them ultra tight and I didn t find the method yet to achieve that. I may use myv sewing machine. Ok goodbye I talk too much....

[Colas LeGrippa]

.......'cause I aint got no friends