Tweeter Clone

[Zero One]

Just for interest here is my latest clone module, hopefully optimised for tweeter use. It will be totally enclosed in a copper case around the circuitry tomorrow once tested, it is as small as I can make it, virtually all P2p SMDs, LM1875 chip, 12V battery supply, gain of 15, 47uf caps with a bank of 10 snubbered 10uf caps per rail, (off board and not shown).

The watch is shown for comparision.

Input/powerwiring is foil wrapped and earthed to the groundplane which is insulated from the heatsink, and the output runs under the heatsink and up through a hole just under the output tab on the chip. I am absolutely determined to kill any chance of oscillation in the search for the "tube clone sound".

[Zero One]

Here is another pic a bit easier to see.

[Nuuk]

What is that yellow cap ZO?

[Zero One]

Hi Nuuk

The yellow cap is a .1 uf bypass on the input 2.2uf input cap, to help keep the highs all sweet, the main input cap is SMD, I could have used a chip cap, however I,m a little dubious about using chip caps in the signal path, hence the MKT.

[Nuuk]

If you are going for the 'ultimate' tweeter amp, you can get away with a much lower value input DC blocker and go for a good quality polyprop, or even paper-in-oil type.

IMHO, polyester types in the signal path are lo-fi rather than hi-fi!

What's a chip cap?

[Zero One]

Hi Nuuk

Yep I agree entirely I will be using a better grade cap, this is a prototype to test a few things, in fact the final modules will only have a small blocking cap, and be fed via an active crossover, so only 6000 Hz and up will be going to the module.
Chip caps are non polarized SMD caps that look, well like a tiny tiny brick, pretty poor quality apparently.

Heres and update, I finsihed the module today with its little copper coffin all around the module and it is running right now, but in full range mode (ie driving my full range speaker set-up) with 3200uf off baord caps and the sound, very very nice, somewhat smoother than the other clone module on the other speaker, nicer mids/upper.

Currently its running on 12smps, but going on my expereince from a couple weeks back I feel the 18v battery set-up with the 100uf cap banks be nicer still once hooked up for tweeter use.

And thanks for your interest and comments, how low do you think I could go on the blocking cap value.

[Circlotron]

"that look, well like a tiny tiny brick,"

I think chip caps look like a little bed with a pillow at each end

[Zero One]

Yep and just about small enough for an errant flea to get a kip on when he gets a bit tired.

[Nuuk]

And thanks for your interest and comments, how low do you think I could go on the blocking cap value.

It takes two to Tango so it depends also on the resistor (input to ground) involved! I'm not sure if there are any other factors affecting how low you can go. But based purely on theory, you could go to something like 10 nF (with 51K).

[Zero One]

The resistor to ground on the input is 1M does that help?

Just put the little fella to sleep after running for 7 hrs, not even warm to touch...lovely