series resistors parallel caps

[a_e_a]

hey guys
i read somewhere that in place of a single resistor you put 2 of half the value (making it the same amount of resistance) in series it can make the tone a little more open. Also wondering if doing something similar with 2 half value caps in parallel in place of a single cap would make a difference tonewise.

Anyone here try things like this? Would mixing types (carbon comp with a metal film etc) make the best of both worlds?

Now I am still fairly green (having only done one build so far) but I am just interested in peoples takes on trying different things. Obviously I am going to try lots of things for myself but just want to pick peoples brains.
Sorry if its been talked about before or if its a stupid question but thanks anyway

[Gaz]

Where did you read that? Sounds pretty nuts to me, and you'd probably have to do it throughout the amp to hear anything. More "open" sounding is silly - I don't even know what that means! I think you're right that you'd have to use two different type (metal film and CC), but since metal films are so relatively transparent, I feel like all you'd hear would be the CC. Optimistically you could get some added stability and noise reduction from adding the metal film, but that's just mad science to me!

Caps, I think, are a different matter, although still yield subtle results. Ken Fischer has famously used poly caps in parallel with a ceramic caps to couple gain stages. Personally I can hear the tone of both types in an A/B comparison, and would like to believe I can hear them summed together as well, but again it's subtle. IMHO, in a live context, these subtleties get completely obfuscated by the din of the band (see: heavy-handed drummer).

[a_e_a]

Hey I am not sure where I read it as I have been going through so many sites to really learn more before I go about my next build. I think it was someones blog somewhere?
I would figure it would be a subtle difference if any and probably a higher cost too but again just trying to get as much info and experiment as much as possible. thanks for your answer

[overtone]

"Open" is really rather poetic.
My advice is to rig up a simple A-B testbed for these notions so that you can make your mind up yourself. You can sort out which ideas cut it for you and which are worth spending time on. The key is knowing your goal, where you want to get to and in which situations the amp is to perform in. Will it cut it? Later on you can use such an A-B test bed and your experiences to hone your amp voicing skills.
Good luck.

[Gaz]

Nice advice, Overtone.

[tubeswell]

i read somewhere that in place of a single resistor you put 2 of half the value (making it the same amount of resistance) in series it can make the tone a little more open. Also wondering if doing something similar with 2 half value caps in parallel in place of a single cap would make a difference tonewise.

Anyone here try things like this? Would mixing types (carbon comp with a metal film etc) make the best of both worlds?

Resistance in series adds up. e.g.: 2 x 10R resistors in series is the same as 1 x 20R resistor. But the power rating sums up. So if both 10R resistors were 1W resistors, then they would offer 20R resistance at an overall 2W power rating (so they will be able to dissipate twice as much heat as 1 x 20R 1W resistor). This would make using the 2 x 10R 1W resistors potentially quieter than using 1 x 20R 1W resistor - where the resistors affect/are in the signal path, and depending on how much voltage the resistors are having to drop.

Capacitance in parallel adds up. So the frequencies passed through 2 parallel caps of the same value would double in wavelength (i.e.: get lower/bassier) because of the increased capacitance. This would certainly change the tone (where the caps affect/are in the signal path) all other things being equal. (However, if 2 x 100Vcaps were in parallel, they can still only cope with 100V altogether. Whereas if 2 x 100V caps were in series, they could cope with 200V altogether, but their overall capacitance would be 1/2 of what a single same-value cap is. e.g.: 2 x 50uF 100V caps in series adds up to 25uF 200V, but the same 2 caps in parallel is 100uF 100V)

Now if you have a resistor of a given value and a cap of a given value in parallel, they produce a frequency boost roll-off point of a certain value. If you double the resistance and 1/2 the cap value, you will get the same frequency roll-off point. Similarly if you 1/2 the resistance and double the cap value, you will get the same frequency roll-off point. Whereas if you keep (say) the resistor the same, but double the cap value, you double the bass frequencies that are able to be bypassed, and so on.

[Super_Reverb]

hey guys
i read somewhere that in place of a single resistor you put 2 of half the value (making it the same amount of resistance) in series it can make the tone a little more open. Also wondering if doing something similar with 2 half value caps in parallel in place of a single cap would make a difference tonewise.

Anyone here try things like this? Would mixing types (carbon comp with a metal film etc) make the best of both worlds?

What happens when you series and parallel components is you obviously change the primary component value by well established physical principles, but you also change parasitic or secondary effects. For example, when you parallel caps, you may reduce the overall series resistance, which affects its filtering and AC transmission characteristics.

The most important principles are good components usage, good circuit design, and sturdy construction. Once you have these understood and mastered, a builder can grow in his hobby/business through experimentation and other development activities.

If you make a circuit change, you should be able to hear a difference. You can't really say something is better or worse in an amp, ifn you can't hear it.


cheers,

rob