Well, you could, but you would have to remember that the sub level was tied to the center channel level, but sure it would work, and it would ony take 3 PCBs.rabstg said:
One other thing to remember is that the pots would not have to be panel mount mechancial pots, they could be digitally controlled pots, and that opens the door to remote control, or rotory encoder with push button, or just buttons, any combo really.
On our stereo in the lounge room when we use the remote to turn up or down the volume, the dial also moves accordingly. I have to say, it's one of the coolest things to have, and I absolutely love it.
How would I be able to add that to a kookaburra?
Sorry I'm absolutely new to all this (not electronics, but audio gear), and this will probably be my first amp/preamp building project, so apologies for the probably silly questions. 😵
Cheers,
--Nathan
How would I be able to add that to a kookaburra?
Sorry I'm absolutely new to all this (not electronics, but audio gear), and this will probably be my first amp/preamp building project, so apologies for the probably silly questions. 😵
Cheers,
--Nathan
Wow I can't believe I missed this thread on such a cool topic, made even more cool for me since I just designed a (and partly built so far) an 8 channel, 6.1/2, preamp with 8 digitally selected inputs (this option I am still testing but for now I think it sounds OK). Option to sum mains for the sub or run stereo and even run summed front / rear and a digially contolled volume control using the Intersil X9C303 controlled by rotary encoders for both volume and input.
I am using the $2.03 Panasonic EVE version from Digi-Key, it's quite nice but I can only get the detented version in low torque. Still looking for a supplier of the detent-less low torque for volume to emulate the feel of a pot better.
Funny thing is I abandoned using a micro and built it all out of individual gates, works well but is complex... maybe the micro was a better choice seeing this design
MunkeeVegetable not 100% sure but in my experience the volume control you described is a pot with a built in motor to move it. it's neat and all but a) they are damned expensive and b) the motor would draw a fair but of currrent might be too much for the regulators. Otherwise it behaves just like a normal pot.
Anyone care to tell me if using the digital pot directly in the signal path of something like a OPA604 will degrade the sound considerably?
Right now I have it set up as the ground path for a voltage divider so the audiable signal never flows through the pot just a single 33K fixed resistor.
I am using the $2.03 Panasonic EVE version from Digi-Key, it's quite nice but I can only get the detented version in low torque. Still looking for a supplier of the detent-less low torque for volume to emulate the feel of a pot better.
Funny thing is I abandoned using a micro and built it all out of individual gates, works well but is complex... maybe the micro was a better choice seeing this design
MunkeeVegetable not 100% sure but in my experience the volume control you described is a pot with a built in motor to move it. it's neat and all but a) they are damned expensive and b) the motor would draw a fair but of currrent might be too much for the regulators. Otherwise it behaves just like a normal pot.
Anyone care to tell me if using the digital pot directly in the signal path of something like a OPA604 will degrade the sound considerably?
Right now I have it set up as the ground path for a voltage divider so the audiable signal never flows through the pot just a single 33K fixed resistor.
To use a digital pot as a volume control, you really need to impliment a wheatstone bridge for it. Dallas Semi has a good paper on this. Search their site for DS1802 (one of their volume controls), paper is about implimenting digital pots as volume controls.
Anyway, we are using the venerable PGA2311PA, which is very good, very clean, and, of course, very expensive. Highly recommended though. Use the PA version.
Anyway, we are using the venerable PGA2311PA, which is very good, very clean, and, of course, very expensive. Highly recommended though. Use the PA version.
Thank you 😱 I can't believe I did that... For now I will continue with my current design, with the wheatstone bridge. Cost is a factor due to needing to build 8+ of these boards.
I think the DS1802 is pretty cheap. You can get them as samples. Oh, if you want to try the PGAs, you can get 5 of them (stereo) as samples.
so for a nice stereo/5.1 preamp one would need:
3 kookaburra boards
one of those nice input selector boards
hook up all 3 boards to one volume pot, use the switchboard (sic) to select the stereo signal going to one of the kookaburra's.The front channels of the 5.1 input are routed through this board aswell. The remaining four 5.1 signals go directly to the other two kookaburra's. That, or use the +V of the relays on the switchboard to switch these four channels aswell.
This way you have a single 5.1 input and 2 stereo inputs.
Take a good dvd player (panasonic?) with 5.1 outs and hook it up to the 5.1 input. For stereo stuff, use anything you like (say the same dvd player with a nice reclocking dac or something).
This gives you a nice and compact stereo/5.1 setup. Be that sacd or movies or whatever.
Or, better still...
Get/build a remote control board which allows you to change the volume and switch the inputs.
Russ, I think you said:
what about a 6ch kookaburra? 😉 Shouldn't be too much work as the basic system is finished!
Great project!
3 kookaburra boards
one of those nice input selector boards
hook up all 3 boards to one volume pot, use the switchboard (sic) to select the stereo signal going to one of the kookaburra's.The front channels of the 5.1 input are routed through this board aswell. The remaining four 5.1 signals go directly to the other two kookaburra's. That, or use the +V of the relays on the switchboard to switch these four channels aswell.
This way you have a single 5.1 input and 2 stereo inputs.
Take a good dvd player (panasonic?) with 5.1 outs and hook it up to the 5.1 input. For stereo stuff, use anything you like (say the same dvd player with a nice reclocking dac or something).
This gives you a nice and compact stereo/5.1 setup. Be that sacd or movies or whatever.
Or, better still...
Get/build a remote control board which allows you to change the volume and switch the inputs.
Russ, I think you said:
what about a 6ch kookaburra? 😉 Shouldn't be too much work as the basic system is finished!
Great project!
matjans said:
Thanks man. 🙂 Its been a really fun project, at first I was very worried how it would turn out, but it performs much better than I had hoped. 🙂
Keep watching I have something in the oven you will want to see, but have a few othe things to finish up first. 🙂
Cheers!
Russ
matjans said:
Texas Instruments actually manufacturers a sister-device, the PGA4311 which allows 4 channels. It's a 28 SOIC.
jackinnj said:
Exactly! 🙂 The 7.1 Pre I am currently working on (almost done) uses two of them.
Cheers!
I can't wait till we can buy the kits!
I have my toroidal and enclosure sitting here waiting. *Bounces excitedly*
After exams, this preamp is miiine! MINE, I SAY! BWAHAHAHAHA
*Scampers away with evil grin*
--Nathan
I have my toroidal and enclosure sitting here waiting. *Bounces excitedly*
After exams, this preamp is miiine! MINE, I SAY! BWAHAHAHAHA
*Scampers away with evil grin*
--Nathan
Well I received the beta kit yesterday and assembled last night. With a few minor hang ups took about an hour and a half. In all went pretty smooth. Great quality kit. I hope to be up and running this weekend. I may need a little help with the transformer hookup and with the jumpers at the input. Brian and Russ are you going to make a assembly guild? If so I can provide a little input on that. I'll keep everyone posted on the progress. 😎
bender460 said:
Hi Bender,
Great you can shoot me an email if you have any specific build input.
I will see about a build guide. I think I could throw one together. 🙂
As far as the jumper for omitting the input buffer it simply goes where R4 and R5 go neer the input buffer, only you put one leg of the 0R resistors(jumpers) in the jumper pads PAD1 and PAD2.
here is a PIC:
Attachments
FWIW I would use the input buffer in most situations, it does just seem to make the thing sound better overall. You can use just about any unity gain stable SOIC dual opamp. A good relatively cheap choice is the OPA2227, or you could spring for another AD8620, you could even use two of either one. I have actually built one with both buffers being OPA2227 and one with both being AD8620, they both sound awesome, and you would be hard pressed to distinquish between the two.
Cheers!
Russ
Cheers!
Russ
Hi there Russ. From your previous posts that is what I thought on the jumpers thanks for clearing that up. An assembly guild is just a thought. I would put myself at a medium level builder. The guild would have only saved me from searching this thread once. So really this thread is a good guild by itself. 🙂 But for a real novice 
We are actually thinking of chaging the op-amp included in the kits to the OPA2227, and including both. This would help keep the cost reasonable,as the 8620s are pretty pricey. Anyone have an opinion about that?
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