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O2 Amplifier Kit & PCB Groupbuy, Worldwide

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#443
pby said:
Iirc carbon film has a higher thermal coefficient which means its more likely to drift out of spec when it gets hot.
Click to expand...

You are correct, and issues did start to arise after 10 or so minutes of play. I have swapped the resistor for the spare 40k metal film and it's working fine.

Also only running off very cheap 9v batteries, can't wait to hear it go when I get some decent batteries.
 
#444
Do the batteries make a difference? How does one distinguish between good and bad ones?

I do recall from diy stompbox projects that some people favoured zinc acid batteries for their properties as the juice ran out, but that is presumably not an issue for a headphone amp.

Regards, Chris.

PS stompboxers also like carbon resistors for a more 'authentic' sound.
 
#445
I also was missing a 33k resistor so raided my supplies. IMHO I can't see that having a carbon film or metal film would make much difference since R9 is just used to set the threshold for cutting off the batteries as they go flat. It is not in the signal path. The voltage across the LED, which is the other reference point, is far more likely to drift with temperature. Cheap 9v batteries are also likely to be far more variable.

Regards

Paul
 
#448
Received parts 2 days ago, checked everything seems to be there exept R9 33K.

thanks for the quick shipment.

However i somehow seem to have damaged Q1 or Q2, all though, i have been very carefull with them (keep in esd bag, soldering as short as possible).

Have you got spares of those and maybe R9?

Just let me know cost including postage to the Netherlands and i wil transfer via paypall

Regards Florus
 
#454
Hi Jokener,

I just finished checking the parts.

Resistors
I have received some resistors that are not in the BOM:

  • 1 x 2.7M
  • 1 x 330K
  • 1 x 40.2K too many (4 instead of 3).
I have not received 1 x 33K (R9).

Capacitors
I have received 6 (instead of 4) 0.22uF 63V MKT/MKS (C10, etc.).
I have not received C6, C7: 1.0uF >=25V MLC 5mm LS

The rest seems to be complete and thanks for throwing in the extra pcb. Not sure yet if I will use the blue or black!

The 33K resistor should not be a problem. I should be able to get one at the local Jaycar shop. The capacitors are a problem. I just checked and they do not have 1.0uF MLC. They only seem to have tantalum.
1uF 25V Tag Tantalum Capacitor - Jaycar Electronics
Would this work (if they have it in stock)?

Albert
 
#455
albertNL said:
Resistors
I have received some resistors that are not in the BOM:

  • 1 x 2.7M
  • 1 x 330K
  • 1 x 40.2K too many (4 instead of 3).
I have not received 1 x 33K (R9).

Capacitors
I have received 6 (instead of 4) 0.22uF 63V MKT/MKS (C10, etc.).
I have not received C6, C7: 1.0uF >=25V MLC 5mm LS

Albert
Click to expand...

Hi Jokener,

same accounts for my order, you might want to check your pre-packed kits.
I will source the missing parts locally.

Stefan
 
#456
The 40.2k resistor and the 2.7M resistors are suitable for R9, it depends witch version of the O2 you're building, the low power or the normal, these are the old values, witch are fine too according to Rocket Scientist, if you don't believe me check at his blog, under O2 details.
 
#459
swalter said:
Hi Jokener,

same accounts for my order, you might want to check your pre-packed kits.
I will source the missing parts locally.

Stefan
Click to expand...

My kit was the same but the only part you need to source is the 33k R9, which used to be 40k which is supplied.

There is an inconsistency between the BOM and the circuit diagram I have. I used all 6 of the 0.22uF caps. C6 and C7 are 0.22uF on my diagram but 1.0uF on the BOM.

My amp sounds great. I went for 2 x Gain on low and 5 x on high as the source is my Colorfly.

141502903.jpg


141502904.jpg


Cheers, Tony
 
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