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turion64

turion64

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JLesterP said:
I agree, OPA1656 is cleaner and clearer sounding.
Just need to tame it with ELNA Silmic II or other compatible caps, otherwise it will sound sharp.

I ordered small quantity on digikey, it is out of stock on Mouser!
Click to expand...

1656 are out-of-stock here in USA for both Digikey & Mouser as of yesterday.

I’ll try putting the Silmic’s back (pre-3255 only) to see what is sounds like with the 1656s

Pete
 
D

Deleted member 148505

Hot air is not needed, you just need to put solder blob on the cap and drag it back and forth until the smt cap dislodges.

Regards,
Lester

stef1777 said:
Hello!

I confirm better without the feedback caps. How small are these capacitors!! Impossible to use air flow. Too close from the op-amp sockets. :D

No yet back with PFFB. Ive to change the green 22uF caps for Elna first.

Cheers,

Stéphane
Click to expand...
 
turion64

turion64

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stef1777

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github.com/stefaweb/Q17-Amplifier
JLesterP said:
Hot air is not needed, you just need to put solder blob on the cap and drag it back and forth until the smt cap dislodges.
Click to expand...

This is what I did, also using small tweezers. It's fast and it doesn't heat up the pcb.

On the other hand, I had to resolder the Elna on the top of the PCB because the spacers I used are too short. The caps did not hold out. I still have the four 22uF in front of the opamps to change. I would do that tomorrow by handing over the PFFB bridges to try.
 
turion64

turion64

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turion64 said:
I have WIMA 1uF caps pre-3255 right now but I’ll put back the Silmic IIs later today to hear the difference. I’m also running OPA1656s.

Cheers, Pete
Click to expand...

So I didn’t have 22uF Silmics but I did have 10uF ones that I had burned in on the 3e Audio board. I put them in pre-3255. Using 1656 at this point. Your "bloomy" sounds returned. Overall a warmer, more lower frequency oriented sound. Upper end frequency "airiness" is diminished but if you prefer this type of "bloomy" sound (not a negative thing) it’s perfectly good.

I’ll test nichicon UES bi-polars (10uF) in this position next.

Pete
 
D

Deleted member 148505

Hi Pete, Now is a right time to enable pffb while Elna Silmic II is soldered.
Although your preference might be the WIMA.

There might be more mods along the way. But so far removing the caps is the best :).

Thanks,
Lester
 
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D

Deleted member 148505

stef1777 said:
This is what I did, also using small tweezers. It's fast and it doesn't heat up the pcb.

On the other hand, I had to resolder the Elna on the top of the PCB because the spacers I used are too short. The caps did not hold out. I still have the four 22uF in front of the opamps to change. I would do that tomorrow by handing over the PFFB bridges to try.
Click to expand...

Hi Steph,

You don't need to remove the 22uF green muse caps near the input terminals. They are good already, unless you want to replace them with larger poly caps.

Regards,
Lester
 
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stef1777

Member
Joined 2004
github.com/stefaweb/Q17-Amplifier
Too late.

I replaced them with Elna Silmic II too. I've avec un bag of them from another project. ;)

I also added a shield around the power plug and twisted the 48v wire.

PFFB is back.

I've also to short input signal wire and to modify the speaker output with a protection board but still waiting for it.

I'll let you know the new sound signature.

Cheers,
 

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D

Deleted member 148505

I'm comparing them right now, Muse BP has more air.
After the removal of feedback caps, I can confidently say that PFFB is better sounding compared to non-pffb.

ELNA Silmic II near TPA3255
Nichicon Muse BP near input terminals.
OPA1656

Also I'm using 2.2ohms on RA7, RA8 (please do not use 0 ohms, this resistor is the secret to stability)
 

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J

jimk04

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I hope to get my JLE 3255 in my system soon. Just have the 1800ufs to solder and the heatsink to attach before wiring up.

What mods that have been talked about here should I do from the outset. ?
Some will be subjective I understand but which are deemed to be essential developments to the board?
Remove these tiny feedback caps?
I shall run it with the 49860 and provided caps for now.
Where is the pffb jumper/solder blob?
Thanks in advance!

And what sort of cap should I use Lester for that modification you emailed me about.?

Cheers
 
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