Nice work Veteren.
Much like another complex preamp I am working on, but not really much like this preamp/headamp that is the subject of the thread as the design goals are nearly entirly different. 🙂 Still its a great implementation of the PGA2311/10.
Keep your eyes open though, as there is something in the works which will have all the bling. 🙂 LCD/IR the works, but it also will cost quite a lot more than kooka does. 🙂
Also keep in mind kooka is designed for both high impedance sources and low impedance loads (thus the buffers) a PGA2311/10 on its own does abismally with either high source or low load impedance. So the kooka was designed to be very flexible and especially for the two major roles it plays:
1) Buffered preamp.
2) headphone amp.
The inclusion on this design of a purely tactile analog interface (single pot) is completely intentional. For those who want an LCD or some other UI it would be very easy to control the kooka from another controller PCB. Just ask me if you want to know how.
As I said at the beginning of the thread, this is my first serious attempt at any MCU controlled audio project. 🙂 So I have learned a lot from it.
So in short design goals for me were:
1) Low cost.
2) Smooth silent control with soft ramp up.
3) Very good digital side isolation with minimal induced noise.
4) Small size.
5) Simple UI (just one pot).
6) Flexbile application (no buffers, output buffer, input buffer or both).
7) Stackable (you can use a single kooka for a balanced channel).
8) Easily modable by DIY users. Adding LCD and IR to kooka would not be terribly hard at all, but adds pretty significantly to the cost and complexity factor.
So yes there are a number of very good PGA2311 designs out there, but they are typically at their core designed with a different set of priorities.
Attached is a sneak peek of the latest version of the kookaburra PCB. These PCBs will be ordered this week.
Kooka Version 1.1
BTW Bob, I have not forgotten about the active x-over. I am actually working on a prototype today based on the PCB designs I have previously showed you. Just ironing out details in the interface/controller PCB.
Much like another complex preamp I am working on, but not really much like this preamp/headamp that is the subject of the thread as the design goals are nearly entirly different. 🙂 Still its a great implementation of the PGA2311/10.
Keep your eyes open though, as there is something in the works which will have all the bling. 🙂 LCD/IR the works, but it also will cost quite a lot more than kooka does. 🙂
Also keep in mind kooka is designed for both high impedance sources and low impedance loads (thus the buffers) a PGA2311/10 on its own does abismally with either high source or low load impedance. So the kooka was designed to be very flexible and especially for the two major roles it plays:
1) Buffered preamp.
2) headphone amp.
The inclusion on this design of a purely tactile analog interface (single pot) is completely intentional. For those who want an LCD or some other UI it would be very easy to control the kooka from another controller PCB. Just ask me if you want to know how.
As I said at the beginning of the thread, this is my first serious attempt at any MCU controlled audio project. 🙂 So I have learned a lot from it.
So in short design goals for me were:
1) Low cost.
2) Smooth silent control with soft ramp up.
3) Very good digital side isolation with minimal induced noise.
4) Small size.
5) Simple UI (just one pot).
6) Flexbile application (no buffers, output buffer, input buffer or both).
7) Stackable (you can use a single kooka for a balanced channel).
8) Easily modable by DIY users. Adding LCD and IR to kooka would not be terribly hard at all, but adds pretty significantly to the cost and complexity factor.
So yes there are a number of very good PGA2311 designs out there, but they are typically at their core designed with a different set of priorities.
Attached is a sneak peek of the latest version of the kookaburra PCB. These PCBs will be ordered this week.
Kooka Version 1.1
BTW Bob, I have not forgotten about the active x-over. I am actually working on a prototype today based on the PCB designs I have previously showed you. Just ironing out details in the interface/controller PCB.
Attachments
There is a simple way to connect a (buffered) pre- and headphone amplifier 😉 Al-in-one can be made using WM8816 stereo digital potentiometer. Engineers from Wolfson equipped their chip only with resistors array and logic. Volume control take place in external operational amplifier. I made several tests using different op-amps. So, if You use hi output current one – like OPA552 – You will receive a nice headphone amplifier with volume control 😉
I called this WM-STAMP. Optoisolation and (+)5V power supply included 😉
I called this WM-STAMP. Optoisolation and (+)5V power supply included 😉
An externally hosted image should be here but it was not working when we last tested it.
Member
Joined 2002
Id really like to see a nice lcd pre amp /. source selector. I have a 200$ display red that i really want to use in a project. basically i'm looking to help / start a project that uses relay attenuation for the volume out put. Right now i'm using one of digi01's volume relay passively used volume pot's and it is working PERFECCTLY love it so much..
I'm willing to help and contribute.
I'm willing to help and contribute.
Member
Joined 2004
Input Source selection
Hi Jleaman:The pre-amp that I designed utilizes a pair of the Analog Devices SSM2404 switches for input source selection(pic controlled),they work flawlessly in this application as they are characterized for audio use.
Using two of these devices gives you the ability to switch 4 stereo input sources.
Regards Bob C.
Hi Jleaman:The pre-amp that I designed utilizes a pair of the Analog Devices SSM2404 switches for input source selection(pic controlled),they work flawlessly in this application as they are characterized for audio use.
Using two of these devices gives you the ability to switch 4 stereo input sources.
Regards Bob C.
Member
Joined 2002
Member
Joined 2004
For Russ White
Russ: I am looking forward to seeing the successor to Kookabura..I just have a thing for Bling!..
You(Twisted Pear) do a fantastic job with all of your projects and I wish you even more sucess in the coming year.
Best Wishes Bob C. 🙂
Russ: I am looking forward to seeing the successor to Kookabura..I just have a thing for Bling!..
You(Twisted Pear) do a fantastic job with all of your projects and I wish you even more sucess in the coming year.
Best Wishes Bob C. 🙂
Member
Joined 2004
For Jleaman
Hi: I am not sure if I am allowed to answer your question,it seems like I am off topic with my post....I thought this was a public forum??
Regards Bob C.
Hi: I am not sure if I am allowed to answer your question,it seems like I am off topic with my post....I thought this was a public forum??
Regards Bob C.
HI Bob, I think Brian was just trying to say that since its a new topic (and a good one) that it deserves its own thread.
Thanks for everything.
Thanks for everything.
Member
Joined 2002
Member
Joined 2004
For Russ
Hi Russ: The information that was posted by me was not "Off topic" it relates directly to the pre-amp discussions that have been ongoing.The "Abrupt" posting by Mr. Donegan appears to be an attempt to tell me and others to politely Shutup...and go away.
Bob C.
Hi Russ: The information that was posted by me was not "Off topic" it relates directly to the pre-amp discussions that have been ongoing.The "Abrupt" posting by Mr. Donegan appears to be an attempt to tell me and others to politely Shutup...and go away.
Bob C.
Tom,
If you are still having problems with your kookaburra email me off the forum, perhaps you could ship it to me, I may be able to fix it quickly.
Cheers!
Russ
If you are still having problems with your kookaburra email me off the forum, perhaps you could ship it to me, I may be able to fix it quickly.
Cheers!
Russ
Member
Joined 2002
Russ White said:
That was the best response i have seen for customer service.. Id say that was a great idea this kinda stuff guys is what is going to keep people coming back here and want to do business with russ.
Good job..
Jason
Um, sorry if I came off that way (kids yelling at me while I type). Just meant what Russ said. We should start a new thread, as the discussions will get lost here, as the first 350 or so posts were about one design in particular. Didn't mean to sound abrupt or snide.
Member
Joined 2004
My 2 Cents
Brian: There are plenty of talented people who contribute in this forum.The pre-amps that were posted were exceptional examples of what the DIY community can produce.The free and open exchange of ideas is what drives this forum,No one should feel that the few postings were an attempt at thread Hijacking.
No hard feelings...Bob Cottiers
Brian: There are plenty of talented people who contribute in this forum.The pre-amps that were posted were exceptional examples of what the DIY community can produce.The free and open exchange of ideas is what drives this forum,No one should feel that the few postings were an attempt at thread Hijacking.
No hard feelings...Bob Cottiers
Dude, I'm not concerned about thread hijacking.
I just don't want ideas/suggestions lost in a giant thread that has been mostly about one particular design. That is all.
I mean/meant no hostility or ill will, and welcome the ideas and designs. Let's nip this in the bud and let it go.
Now that I have more then 30 seconds to type (son is napping)...
Bob: Do you use rotary encoders for both volume and source, or a pot for volume (like the kook) and a rotary switch for the source? Also, what kind of finish did you use on your cases?
Veteran: Your stuff looks very nice indeed! Good diversity of gear on your site.
I just don't want ideas/suggestions lost in a giant thread that has been mostly about one particular design. That is all.
I mean/meant no hostility or ill will, and welcome the ideas and designs. Let's nip this in the bud and let it go.
Now that I have more then 30 seconds to type (son is napping)...
Bob: Do you use rotary encoders for both volume and source, or a pot for volume (like the kook) and a rotary switch for the source? Also, what kind of finish did you use on your cases?
Veteran: Your stuff looks very nice indeed! Good diversity of gear on your site.
Member
Joined 2004
Brian: I use a pot for both volume and input selection,the input selection pot is divided into 4 quadrants,IMO this is preferable over a rotary switch(cheaper).
I use rub on poly for the cases.
I think this matter is cleared up.
Regards Bob C 🙂
I use rub on poly for the cases.
I think this matter is cleared up.
Regards Bob C 🙂
Thank You Brian 😉
There is also place for rotary encoder on my pga2310 module (ECW1J from Bourns) but I don’t like the way it works (this feeling, reminds me volume knobs in chip hi-fi systems 😉. I’m thinking that stepper motor may be useful in here.
There is also place for rotary encoder on my pga2310 module (ECW1J from Bourns) but I don’t like the way it works (this feeling, reminds me volume knobs in chip hi-fi systems 😉. I’m thinking that stepper motor may be useful in here.
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
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
Yes, and I also think that Wolfson chip is better. If You use a proper op-amps there are no problem to drive low impedance loads. I tested WM8816 with OPA627, 604, 134, AD825, 817, LM6171 (recommend this one)…
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