Caps and resistors for HiFi

[überfuzz]

Hi!

I'm in the process of designing and later building a HiFi amp. I've only built guitar and bass amplifiers prior to this build. Well, HiFi is kind of 'out of my jurisdiction'. What passive components should I opt for in this solid stage HiFi amp?

[Leo_Gnardo]

Well, HiFi is kind of 'out of my jurisdiction'. What passive components should I opt for in this solid stage HiFi amp?

Hardly 'out of your jurisdiction.' Need your amp be solid snake? How much power do you need? IMHO the power amp section found in most classic Fenders makes a fine hi fi amp. One of the drawbacks of most amps found in hi fi is too much gain. If you have a strong enough preamp, you don't need a hi sensitivity power amp. Takes a couple of volts (about a +12 dBm signal) applied to inverter input to run those Fenders to full output, almost any signal source can do that. If you find you need more, simply add a single triode to boost your signal. And you can add a switch to use or bypass that, you're building your own. Same with the feedback loop. You can switch it in or out, or add a pot to vary to your ear's content.

Simplicity yields clarity.

If you really need oodles of power & want to go solid state, I'm sure the suggestions will start to roll in any second now...

[überfuzz]

Hardly 'out of your jurisdiction.' Need your amp be solid snake? How much power do you need? IMHO the power amp section found in most classic Fenders makes a fine hi fi amp. One of the drawbacks of most amps found in hi fi is too much gain. If you have a strong enough preamp, you don't need a hi sensitivity power amp. Takes a couple of volts (about a +12 dBm signal) applied to inverter input to run those Fenders to full output, almost any signal source can do that. If you find you need more, simply add a single triode to boost your signal. And you can add a switch to use or bypass that, you're building your own. Same with the feedback loop. You can switch it in or out, or add a pot to vary to your ear's content.

Simplicity yields clarity.

If you really need oodles of power & want to go solid state, I'm sure the suggestions will start to roll in any second now...

I see that my opening post was unclear regarding what im going to build. It's for a preamp in a mic. A common source gain stage is just about all it is going to be. A grid and a cathode resistor, and a Miller capacitor is what im looking for.

[Enzo]

AMps are amps, why would you need any other kind of parts for a hifi than a guitar amp? The preamp will differ, because the goals are different.

[überfuzz]

Well, to be honest, i never got the "right capacitor resistor" thing. If anyone could shed some light on this id be all ears.

[Justin Thomas]

I think everyone is saying "use the exact same parts in your hifi that you would in your guitar amp." Come to think of it, I doubt very much that any commercially made (yet highly regarded) mic preamp uses more expensive parts than any homebrew guitar amp. I mean, what's the going rate in Orange Drops & Mallory 150s vs. what's in any commercial piece of gear?

Justin

[überfuzz]

Hm.. When you put it that way.

Maybe i could mess around with different kinds of components later on when the mic is done..? For curiosity..

[Leo_Gnardo]

Well, to be honest, i never got the "right capacitor resistor" thing. If anyone could shed some light on this id be all ears.

No worries, in a mic pre you need low noise. Metal film resistors, there you go. I'd overspec as far as power goes, because heat also brings noise. 1 watt metal films are cheap enough. Good film caps too - I happen to like Mallory 150 but you can select any OD or go up the expense- & hipster-acceptable chart with Sozo or Jupiter or Russian teflon or whatever. The Mallory's sound clean & clear to me in both solid state and tube equipment.

Miller capacitor? I'm unsure what you mean by that. Why not post a schemo of a mic pre along the lines of what you'd like to try.

[Justin Thomas]

I was thinking that some $.05 Panasonics or Nichicons would work just fine... Mallories & Spragues cost too much, let alone all that other junk! :O

Justin

[Mick Bailey]

AMps are amps, why would you need any other kind of parts for a hifi than a guitar amp?

You Sir, are clearly not a True Believer. In fact, hifi needs parts of a specification exceeding those required for space exploration. It is so and can never be otherwise.

[Enzo]

I'm a damned pagan heathen.


Now that I read post #3, I am asking is this a little circuit INSIDE a microphone? Which is different from a "microphone preamp".

[Chuck H]

The real difference won't be the components. Rather, it will be in the design. And it won't take much research to narrow the circuits either. It's not as if this hasn't been done before. That you are stepping up to this at all is indicative that you can handle it. As mentioned, use metal film resistors. Over spec. I'll endorse Hammond iron for it's relative affordability and performance. Caps are caps, but use polypropylene and mica because of it's good rep and more consistent performance across operating temperatures. Research negative feedback, local and global, for distortion reduction. I've only ever THOUGHT of doing this though. But these are the things I thought about

[überfuzz]

Okay, it's a inside a mic pre preamp..? It's just a common source gain stage thats going to buff the signal some 25-30 dB.

[Mick Bailey]

I see quite a few internal mic preamps and they don't use anything special, just good quality components. SE tube mics use 1W metal film resistors and film caps, and stock low-profile electrolytics. Rode uses largely SMD where possible in their SS condenser mics.

A consideration is to build a transformerless design with SS - lower noise, flat response, cheaper, more space.

[J M Fahey]

Parts are parts, what matters is what they *measure* (how many pF is this 100pF cap? , how many Volts does this 160V cap stand? , how many ohms does this 10k resistor have? and so on).

Which is *amply* covered, way over engineered in modern parts by any serious manufacturer.

Parts are made by the hundreds of millions, price competition is cutthroating, and the only way to get sales is to make a good, consistent and cheap product.

Consumer products manufacturers can't waste time selecting and testing parts to pick grain from chaff so *they* (who are Techs and Engineers) demand perfect parts which can be trusted blindly.

Such parts are currently available by the zillions *only* because of fully automated (and that's an understatement) robotic machinery of - truly - NASA quality (whatever that means).

Look at a cream of the cream exotic parts "factory", fabled Audio Note in Japan, creators of the famous silver foil (not silver mica) capacitor, silver resistor, silver wound transformer, machined-from-a-solid-silver-block tweeter horn ... fwiw I would NOT buy a silver condom from these guys
Audio Note Factory Tour [English]

this is Mr Kondo holding a handmade Silver foil capacitor which according to him took 3 weeks to make:

A brand-new capacitor that costed almost three working weeks
using this machinery:


of course, Audio reviewers all over the World are *ecstatic* about its quality and sound while everybody and his brother despises "capacitors made in India in a sweatshop"

Ok, look at the machine used in India by generic capacitor maker Epcos (ex Siemens, now part of TDK):

please click the image so it opens full size and details can be better seen.

And this is the sweatshop in Bawal, India:

again click to open full size.

by the way, THIS is one of the many places where good paying US jobs went; what's perfect for Ayn Rand Foundation members, of course.