What exactly is the impact of using different caps? When would you use a certain type?
Can someone point me to some resources or elighten me?
A specific question: what would be the difference using a Mylar cap when a Tantalum cap is recommended?
Hold that thought... I shall return to this shortly, but first....
Biggest thing to make note of is which caps are polarised (i.e. have a positive and negative leg). You could use an electrolytic of the same value in place of a tantalum because they are both polarised and it would still work, but you couldn't replace that same cap with a ceramic as it is not polarised.
Alan, technically this isn't true... you CAN indeed use non-polarized or bipolar caps in places of polarized ones... in fact in many case it is preferential... the problem comes down to SIZE and COST! Polyester caps in an equivalent value/voltage range to an electrolytic are normally 10 times the size, making it impractical to use and costly, though it will prob. sound better (read do less damage) as the dielectric absorption of eletros doesnt sound great, which is why many 'boutique' designs avoid these in the audio path.
The important thing to note is that when using a polarized cap you need to make sure the orientation is correct, otherwise at best the cap fails, at worst it causes damage to the rest of the circuit (exploding caps are not only scary, but burnt electrolyte smells horrible!).
Matt's your guy for that (although it may not be in his own best interest to give out info he's worked hard to acquire). I'm a little out of my depth here, but I think tantalum is often used to replace the lower value electrolytic caps in the signal chain and poly or mylar caps to replace ceramic. Metal film resistors are used to replace carbon comp. Also, with the overdrive circuits it seems that the chip choice is an important one if you are chasing a hifi sound.
Let it be known that I have no secrets, much of what I know was thought to me by my mentors who had open book policy, I will always endeavor to offer the same to those that ask ?
Your assessments are correct, tants are often used for not only tonal reasons, but longevity, the one problem is when they die they short out, which is not fun, typically electros go open circuit under normal dielectric break down.... In Horowitz and Hill's "The Art of Electronics" they detail the pros and cons of each (a great book for all electronic fiends).
An interesting aside, South Africa has some of the largest tantalum deposits in the world... we mine it here but all the processing happens abroad, and we buy them back for 100 times the price ?
Ceramics are generally best used where tone is not a major concern. I tend to use them in feedback loops, preventing oscillations etc. And when using ceramics best to go with the better quality NPO types.
Polys generally sound better in the audio path, but then you get poly's and you get POLY's. My preference are the German made WIMA's. I love the way they sound... and no snake oil here... you CAN hear a difference... I once built a mic pre with WIMA's in one, Panasonics in the other and no other changes, very different freq response both on paper and to the ear... WIMA's have a nice top end clarity to them, and are a choice of many boutique designers. Other nice brands are Epcos, Panasonic, Cornell Dublier, Sprague etc.
RE electros I like Rubycons. I use the YXF range, they are high temp, long life, low ESR types, designed for Audio applications. Nichicon and Panasonics are also good bets... I tend to stay away from the Jamicon/Hitone chinese variants, esp. in the audio path.
RE metal vs carbon film resistors... metal is cleaner, so in some circuits like overdrives/distortions it will clean up alot of extra noise, that may or not be a desired effect.
I hope that helps! Just yell if you have any more questions.
Cheers
Matt
