How do you choose type of cap for an amp build?

[BlueX]

I'm making parts list for my second amp build (18W), and I'm down to caps and resistors. However, I don't understand which type of cap to put in different positions. Value (Farad) and voltage rating I get from the layout and schematic.
- Type: Axial, radial, aluminium, ceramic, polyester, polypropylene, polystyrene, silver mica, ...
- Position: Reservoir, filter, coupling, bypass, tone/bright, ...
Is there any guidance on how to select type for position? (I also want to have some vintage vibes)

When I search on this topic I get info related to general electronics, including HF, which might not apply to guitar amps. I also find info on e.g. temperature dependent characteristics, but don't know if that's relevant here. I would appreciate any input, or directions to informative text (that I don't find).

Some background: My first amp build was a kit. For this second project I want to build a 2CH/Tremolo/Tone 18W. Most kits (I found) are Lite or TMB versions, so I started to make a parts list myself.

 

[Jon Snell]

Axial and radial depend entirely on the build and can be both electrolytic and poly etc. PCB build usually use Radial as both leads at at one end and ease of fitment. Radial means lead out of both ends, usually used in hand wired turret or tagboard type builds.
The type of capacitor; rule of thumb, smoothing DC use electrolytic. Signal and coupling, use poly/ceramic/silver mica etc.
A lot of builders think that the more they spend on components, the better the sound. I dissagree and put it down to lack of design knowlege or too much money to spend.

So, electrolytics for decoupling and smoothing, Ceramic/Paper/Poly/Mica for coupling and filtering of signal lines.

Edit: More info added.

 

[Marcomel79]

What amp are you building? PCB or turret board?

 

[BlueX]

What amp are you building? PCB or turret board?

Turret board

 

[Marcomel79]

Then you want to use axial caps. Last build i used metalized polyester, Vishay Rorderstein MKT 1813, rated 630V. The same Marshall uses forr their handwired series.
Filter caps i used F&Ts. Mains, Screen and PI rated 500V, preamp rated 450V. Bias and bypass caps i used generic ones. For an18W i got bias caps rated 63V, if i was building from scratch, id go for 100V for peace of mind. 63V for bypass. Silver mica 500V for tone stack and treble peaker. Little ceramic 1Kv for bright cap. Youre gonna hear different things from different people.....

 

[BlueX]

Then you want to use axial caps. Last build i used metalized polyester, Vishay Rorderstein MKT 1813, rated 630V. The same Marshall uses forr their handwired series.
Filter caps i used F&Ts. Mains, Screen and PI rated 500V, preamp rated 450V. Bias and bypass caps i used generic ones. For an18W i got bias caps rated 63V, if i was building from scratch, id go for 100V for peace of mind. 63V for bypass. Silver mica 500V for tone stack and treble peaker. Little ceramic 1Kv for bright cap. Youre gonna hear different things from different people.....

Any reasons for your choices, if I may ask?

 

[Marcomel79]

Any reasons for your choices, if I may ask?

I saw the coupling caps being used by Marshall. F&T filter caps are very good quality, most people here use them. As for silver micas, youll get mixed responses.
Bias and bypass caps depending what supplier had in stock....

Btw, im also still learning so dont take my advice as gospel....

 

[john l]

I split the diffference between silly and practical. Since mustards and polycarbonate chicklets hog the spot light some of the later makes Marshall used in the cascaded JMPs have gone relatively unnoticed and remained cheap and somewhat available. My favorite of these, despite being a radial make, utilizes long leads and can be used in place of an axial. I save my stash of mustards for restorations and keeping my own amps up to snuff.

 

[matttornado]

Mallory Caps are great in Marshalls and are affordable. I used orange drops too with a few repairs because that's what I had lying around and they work and sound great too.

 

[paul-e-mann]

I'm making parts list for my second amp build (18W), and I'm down to caps and resistors. However, I don't understand which type of cap to put in different positions. Value (Farad) and voltage rating I get from the layout and schematic.
- Type: Axial, radial, aluminium, ceramic, polyester, polypropylene, polystyrene, silver mica, ...
- Position: Reservoir, filter, coupling, bypass, tone/bright, ...
Is there any guidance on how to select type for position? (I also want to have some vintage vibes)

When I search on this topic I get info related to general electronics, including HF, which might not apply to guitar amps. I also find info on e.g. temperature dependent characteristics, but don't know if that's relevant here. I would appreciate any input, or directions to informative text (that I don't find).

Some background: My first amp build was a kit. For this second project I want to build a 2CH/Tremolo/Tone 18W. Most kits (I found) are Lite or TMB versions, so I started to make a parts list myself.

I'd take look at the bill of materials from a few kits and see what they use. It wont explain why but you'll at least get the right parts so you can start building.

 

[BlueX]

I've currently got F&T Al/electrolyte, Mallory 150M axial and Orange Drop radial polyester, and CDE silver mica tone caps in the parts list I'm building (18W/2CH/Trem/Tone).

Noticed that Valvestorm has informative parts lists, or checklists, for their kits. As you said, no explanation why but good hint to what goes where.

Mallory Caps are great in Marshalls and are affordable. I used orange drops too with a few repairs because that's what I had lying around and they work and sound great too.

I'd take look at the bill of materials from a few kits and see what they use. It wont explain why but you'll at least get the right parts so you can start building.