inter board connections
Hi Pinkmouse,
Thanks for altering your board layouts.
3 queries;
1. The power ground on the driver and input boards get connected to the signal ground but where? and do you use a resistor?
2. The NFB line from the output feeds through the driver board & then on to the input board. Would it be better to have separate connections direct from the feedback tapping point to the 2 boards? any comments?
3. Can I presume the feedback tapping point is from the output next to the Thiel network and not on the common trace between the output emitter resistors?
Hi Pinkmouse,
Thanks for altering your board layouts.
3 queries;
1. The power ground on the driver and input boards get connected to the signal ground but where? and do you use a resistor?
2. The NFB line from the output feeds through the driver board & then on to the input board. Would it be better to have separate connections direct from the feedback tapping point to the 2 boards? any comments?
3. Can I presume the feedback tapping point is from the output next to the Thiel network and not on the common trace between the output emitter resistors?
Re: inter board connections
Hi Andrew
All the grounds are run separately back to the star ground. I don't currently use a resistor, as there is no need on my test setup.
I have just run it through both. I honestly don't know if there would be any benefit to running them back separately.
On my test setup, I run a rail between the outputs, and connect the feedback to the end, next to the connection to the speaker cable. It would be quite reasonable to run it from the zobel in the final version. Again, I am not currently using one, it is one of the things I will be testing once the board run is underway.
Hi Andrew
AndrewT said:
All the grounds are run separately back to the star ground. I don't currently use a resistor, as there is no need on my test setup.
I have just run it through both. I honestly don't know if there would be any benefit to running them back separately.
On my test setup, I run a rail between the outputs, and connect the feedback to the end, next to the connection to the speaker cable. It would be quite reasonable to run it from the zobel in the final version. Again, I am not currently using one, it is one of the things I will be testing once the board run is underway.
GeWa said:
Still very busy at the moment, but I'm proofing the Gerbers as we speak, finalising a few things so they will be ok for manufacture.
As for outputs, I'm very happy with 1302/3281s. The faster devices may need checking for stability. If someone wants to send me a couple of pairs of each I'll check them out.
Ok
The KSA 50 that I posted pictures of uses these outputs. It has been running for 2 months. No problems. I allready sent my extras to HArai. Sorry.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=53160
K-amps said:If I didnt have enough devices, I'd try the 4281/4302's. High gain and very fast. Ingredients for a smooth sounding OP stage.
The KSA 50 that I posted pictures of uses these outputs. It has been running for 2 months. No problems. I allready sent my extras to HArai. Sorry.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=53160
2 of my toroids arrived!!
I picked up a nice 17kg package today
2 800va toroids! Here's one of them with a 160va toroid next to it! They weigh in about 8kg each so are heavy heavy
I'm currently running 470mv (millivolts!! Not making the same mistake as last time!) bias and the hottest output is sitting at 53deg with a 20deg ambient! Perfect! Going to wind the bias up more later! So far sounds good but no conclusive listening has been done yet as it's "not time" to crank it up
Runs perfectly at that level, getting about +-36vdc
Aaron
I picked up a nice 17kg package today
2 800va toroids! Here's one of them with a 160va toroid next to it! They weigh in about 8kg each so are heavy heavy
I'm currently running 470mv (millivolts!! Not making the same mistake as last time!) bias and the hottest output is sitting at 53deg with a 20deg ambient! Perfect! Going to wind the bias up more later! So far sounds good but no conclusive listening has been done yet as it's "not time" to crank it up
Runs perfectly at that level, getting about +-36vdc
Aaron
Attachments
Coulomb said:
You'll have to ask the Sales and Marketing department. I'm just an engineer.
Seriously, we will probably set up a wiki to gauge approximate order numbers, but I think Mark is planning to get some extras in for latecomers. Brian has also offered to tweak his PSU board for the project, so we may also have a wiki for that to see if it works out out worthwhile.
Then you guys are going to have to decide what we make next!
jacco vermeulen said:Finally you're a Fat Amp Aussie, Aaron !
What is that sleeving in the resin core ?
(those are the only trannie's i enjoy touching)
There's an alloy sleeve through the middle of the resin core for bolting it down
Thanks for the comments, will post any more progress up
Aaron
So i've setup the single channel so far (p/s for the second one is being setup as we speak ) to 500mv bias per device (5 pairs, 37vdc rails!), good for 4 ohm
I'm currently sitting at about 35deg above amibent for the outputs... (thats the device base at the cover junction)... 20deg here at the moment... I'm thinking that's a good temp to stop at as 65 deg on a hot day is ok, much hotter i think will be too hot... The cooling setup isn't perfect yet, going to work on it this weekend and make a "test case" out of some timber just to hold the sink up so it can be fan cooled properly
I think with an 800va toroid and 37v rails i should be able to run 2 ohm quite well... maybe even 1 ohm???? Not sure... Any ideas?
Aaron
) to 500mv bias per device (5 pairs, 37vdc rails!), good for 4 ohm I'm currently sitting at about 35deg above amibent for the outputs... (thats the device base at the cover junction)... 20deg here at the moment... I'm thinking that's a good temp to stop at as 65 deg on a hot day is ok, much hotter i think will be too hot... The cooling setup isn't perfect yet, going to work on it this weekend and make a "test case" out of some timber just to hold the sink up so it can be fan cooled properly
I think with an 800va toroid and 37v rails i should be able to run 2 ohm quite well... maybe even 1 ohm???? Not sure... Any ideas?
Aaron
Hi,
5 pairs should be OK into 2r but I would think that 2 ohms reactive should only be driven by non clipped music type signal. As for 1r I doubt it and 1 ohm reactive, no way.
Those reactive loads will seriously heat the outputs and heatsink and very soon get you into trouble with reduced SOA due to Tc derating.
driving 1 ohm reactive, using my graphical predicter indicates maximum dissipation of about 23.2A at Vce of 37v giving 858w or about 86w per transistor. Pretty dam hot in a few mins (or could that be 10s of seconds?).
5 pairs should be OK into 2r but I would think that 2 ohms reactive should only be driven by non clipped music type signal. As for 1r I doubt it and 1 ohm reactive, no way.
Those reactive loads will seriously heat the outputs and heatsink and very soon get you into trouble with reduced SOA due to Tc derating.
driving 1 ohm reactive, using my graphical predicter indicates maximum dissipation of about 23.2A at Vce of 37v giving 858w or about 86w per transistor. Pretty dam hot in a few mins (or could that be 10s of seconds?).