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O2 Headphone Amplifier GB

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#443
steve jones said:
Oliver,

In an email to me you quoted a price of 5.20 GBP and that's what I paid via Paypal. On the spreadsheet now my total is 5.28 GBP and unpaid. Should I send you another Paypal payment to cover the difference?

Thanks for all the efforts to get this GB moving.
Click to expand...

I'm sure I can cover the 8p myself. The change is in the fact that I had slightly understimated fees (but as you can see, not by much). I don't know why you are marked as unpaid on the spreadsheet - I must have forgotten. I'll update it in a min.

jesusio said:
I'm going to have to cancel, I apologize for any inconvenience. Thank you.
Click to expand...

Not a problem.


Everyone else: thanks for the payments and new orders. I'll be updating the spreadsheet asap.
 
#457
timpert said:
RS components seems to have no supply problem for the volume pot. But their stock might also diminish quickly.

What do you think of the other taper, the 15A instead of the 3B? Part number is RK09712200HA.
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I haven't tried the other taper but it should be fine (some might even prefer it). They're both designed for volume control use. The big difference is the 15A is only at about 18% voltage at half volume--that's 15 dB down from max. The 3B is at 50% at 50% or 6 dB down. Put another way the 15A will be more "touchy" at high volumes (small changes of the the knob make big changes in volume) but less touchy than the 3B below about 70%.

I'll add a note to the O2 Details article on the tapers and pot options.

I've revised the board (not published yet) to also use 15 mm shaft length pots if you cut off the 0.8mm "nub" on the front (which is easy as it's a brittle casting). I avoided the 15mm pot initially because it does require cutting off the "nub" to work with the 2mm panel and push-on knobs. But now the PCB has both footprints (15mm and 20mm). So this allows use of:

Alps RK09712200MY (15mm long "D" shaft 3B taper)
Alps RK09712200MC (15mm long shaft 15A taper)
Bourns PTD902-2015F-A103 (15mm long "D" shaft)
Bourns PTD902-2015K-A103 (15mm long "star" shaft)

And the 20mm shaft pots:

Alps RK097122008T (20mm "D" shaft 3B taper)
Alps RK09712200HA (20mm "D" shaft 15A taper)
Bourns PTD902-2020F-A103 (20mm long "D" shaft)
Bourns PTD902-2020K-A103 (20mm long "star" shaft)

And, if all else fails, you can use a 20K version of the above but the noise performance will suffer a bit:

Alps RK09712200MT (20mm "D" shaft 15A taper 20K)
 
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#458
RS components have over 400 of the RK09712200HA in stock. Also their stock of the originally specified RK097122008T is over 400. So there is an alternative source.

Anyhow, I often prefer a somewhat more relaxed start of the taper, where the big changes occur at the last part of the throw. So I think I'll be going with the 15 taper.
 
#460
Thanks for all the payments so far.

Paypal have seen fit to verify my identity (great timing, eh...) so I'm trying to get that sorted out asap. I can still receive payments fine but I haven't tried withdrawing money yet - if they are blocking that then we'll have to wait until my identity is proven.

Bloomin' paypal...
 
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