Digitally controlled preamp/headphone amp

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#381
Thanks Damian

I would probably use 627 or AD8610/20 as I have them, LM6171.. you recommend this one because of it's soundquality or ability to drive low imp. loads? (just checking, haven't looked it up).
And if I was to build one it's gonna be a preamp.

So.. it isn't so hard to make a 5.1 preamp with the 8816 i guess?
three chips and your ready to go. It's that damn code...

Cheers
 
#382
Performance of LM6171 is very good (sound quality and output current that this chip can deliver).

There are three jumpers on my stamp pcb (J2,J3,J4) for addressing which give us up to 6 channels (3 boards, all of them connected with the same 10 wire cable). 5.1 either balanced preamplifier can be simply made 😉

Programming is the best part 😉
 
#385
ps caps

replaced the 4 panasonic fc 50v 220uf with 4 jamicon 470uf 85' 25volt caps. I don't know if the increased uf is a big factor but in my experience panasonic fc are not to my liking although everyone else thinks the opposite. To me these cheapy jamicon caps have a more neutral sound.

doggy🙂
 
#386
Re: ps caps

doggy said:
replaced the 4 panasonic fc 50v 220uf with 4 jamicon 470uf 85' 25volt caps. I don't know if the increased uf is a big factor but in my experience panasonic fc are not to my liking although everyone else thinks the opposite. To me these cheapy jamicon caps have a more neutral sound.

doggy🙂
Click to expand...


Using 470uf is fine in fact use as big caps there as you can fit if you like. 🙂 Those caps are not a big factor in performance as they are in front of the VREGs. The VREGs will pretty well dictate impedance and such.

Cheers!
Russ
 
#387
Kookaburra's Rockin'

OK, Russ finally helped me figure out what I had done to fudge up my Kookaburra. I had wired up with the little tranny wrong. I assumed I was to parallel the outputs and apply to the circuit. What really needed to happen was to put each tranny output on each rail with the grounds of each connected to the middle AC input. Boy do I feel stupid!!!

But Russ provided some of the best service I've ever received. He helped debug my unit and because some nodes were slightly buggered up by my ham fisted soldering, he even replaced the whole board at cost. Now that's going above and beyond.

The version I have now has the input opamp stuffed. Not sure if this allows better interfacing to my CDP or not.

Sound:
I've got this little Kookaburra hooked up with a very nice VHAudio Flavor 4 PC going into my awesome Mauro MyRef. Rev. A. The sound I'm getting is simply wonderful. I feared the little preamp would be a tad analytical, but it's quite musical. Very clean sounding, but with just the right amount of warmth and body. Synergistically, the Kookaburra seems to go great with the Mauro. Considering it's about $600 worth of amp/preamp gear feeding the very latest Merlin VSM-MM with SuperBAM, it's amazing the sound I'm getting. Can't believe it's so good.

Thanks for all the hard work Russ/Brian. May TwistedPear continue to prosper. You contribution to DIY has been great.
 
#388
Here is what i use for a Volume ( pot )
 

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#390
finally found some time to get started on my kookaburra. i soldered the opamps and they look o.k. but how can i be sure i haven't fried them before adding the rest of the parts? i'm not sure but i had the iron on them a few times and i'm not sure what would be too long with these opamps. i took a few photos but they don't look great. i will try to put them up as soon as pbase cooperates with me.

thanks,
larry
 
#391
#392
tobias_svensk said:
Hello Damian, have you compared the sound of your PGA2310 against the WM8816 (with a good opamp) ?
I have both chips but haven't built anything yet (noob on that programming 🙂)but it feels like the Wolfson would be better.

Thanks
/Tobias
Click to expand...


Hi guys. I have built a PGA2311 control unit for my preamp using a PIC16F88 as the controller. I'm really interested in the WM8816 as well, where are you purchasing/sampling yours from? The big plan is to use this to feed an AD815 opamp. Right now the PGA2311 is working with an OPA627/BUF634 combo, it sounds pretty darn good...but I want to see what a digital pot without an internal opamp will be like.

As for the programming end of things, don't let it scare you. :xeye: Get yourself a copy of Picbasic and order a few PIC16F88 samples from Microchip, build a little JDM programmer, and go for it. All of these volume control IC's use SPI for communication it's really easy to work with. If you are interested I can post the details and source code for my own project. I'm working right now on adding a source selector using SSM2404 chips, and an interface using a QT510 wheel (like the iPOD). Just the one microchip is able to do it all with 16 i/o lines...there will likely be 2 to spare when I am done.

G.
 
#397
wiring trafo to powercon jack

another newb question just to make sure i get it right and don't kill myself in the process. for 230v i wire the two inside primaries together (red and black) and the two outside together(yellow and violet)?

my powercon jack has live, neutral and ground -- do the inside primaries go to live and the outside to neutral or does it even matter? and ground?

almost there!
 
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