DIY Audio General - stuff you're making, tips, advice sought, etc

BTJ3000 Phono prototype werkz!

Gain

Frequency response

Distortion

0.06% @ 0.25V out

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Sounds good in pictures.

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Just got to see if the foo one measures as well :grinning:

It will measure the same, lol

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All that matters :ok_hand:

I’ve bought the component parts to make a 4w fender tweed style guitar amp. A very simple circuit that even I should be able to assemble without buggering it up. 1 input and a volume pot.
It uses a single 6V6 power tube and a single ecc83 in the preamp - should breakup and distort nicely.
The real challenge lies in the wood and metal work to make an attractive-ish chassis / case. Sketched some plans and ordered the aluminum pre cut to size which turned up today.

(If this goes to plan, I may up the anti and build a bigger amp with a 3 band eq and gain / master volume controls)

Should keep me busy for a few weekends. Will post a few pics as i go.

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https://www.youtube.com/watch?v=7D_GFwvHWUU

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Can someone @coco @AmDismal check my homework please?

Have built one of the crossovers as per the Nelson Pass design and think it is ok but not sure if there is a way to test it before connecting the drivers?

(Yes I know it’s a bit heath robinson but tidiness has never been my strongpoint)

top circuit is woofer
middle is tweeter
bottom is midrange

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Wrong post

The wiring looks ok I think, but I’m not sure I would have had them in that order, with the tweeter in the middle. Label them well!

I would suggest getting a cheap car speaker for a fiver that you can test it on. Although to be fair even the tweeter is fucking indestructible unless you put 100W at 50Hz through it for half an hour.

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Nylon bolts ftw

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It means the inductors will be closer to their intended values.

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yep assumed that you were saying the metal of the bolts would be acting as a metal core and skewing the values.

Yes, they’ll all be high.

I must’ve missed the post. What speaker system are these for?

I’m guessing the inductors are sufficiently separated not to be talking to one another. Obviously, in a more limited space, you can orient the coils so any cross coupling is minimised. Not sure whether this layout needs such measures.

JBL L300, it’s the Nelson Pass design.

The inductors are 16cm and 6cm apart which I hoped would be enough.

Wiring looks ok, as Guy says, nylon bolts to avoid messing up the inductor values.

Make sure nothing can short.

I’ve used 1.5mm solid core out of lighting cable and all the junctions are soldered to copper nails into the wood. I’m going to hot glue the caps and then put them into Tupperware boxes.

Stands are being made at the moment by a local chippy in black American walnut and I’ve redone the covers with JBL blue cloth.

Coming together slowly :slight_smile:

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Good stuff Chris
Always fun to see someone falling further down the rabbit hole :grinning:

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Hacked about with some aluminum this afternoon. Metal work, even with thin stuff is always time consuming.

!

Not too bad given the how shit my pillar drill’s chuck is shit and the fact I’ve no idea how you’re “supposed” to do this sort of thing.

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