when can i pay? I have started thinking about the chassis. My plan i to make a 3 channel amp (stereo + sub) driven on one SMPS assuming that opc and Cristi finds a nice solution.
The problem in my case is cooling and power requirement, because i will probably go with the 100W option (~40VDC main rail?) if ocp makes measurements and tests on that. But i'm not sure that my speakers will be on 8 ohms so extra power in the supply would be nice. I don't listen to high volume so it might work without any problems if i'm lucky, even if i have three channels on the same supply.
modushop.biz
This is the chassis im looking at currently, the price is nice and my plan is to put the two stereo channels on one side and the sub channel + SMPS on the other. Will this structure and layout have enough heat dissipation to run passive? I really want to avoid fans or other noisy cooling.
The problem in my case is cooling and power requirement, because i will probably go with the 100W option (~40VDC main rail?) if ocp makes measurements and tests on that. But i'm not sure that my speakers will be on 8 ohms so extra power in the supply would be nice. I don't listen to high volume so it might work without any problems if i'm lucky, even if i have three channels on the same supply.
An externally hosted image should be here but it was not working when we last tested it.
modushop.biz
This is the chassis im looking at currently, the price is nice and my plan is to put the two stereo channels on one side and the sub channel + SMPS on the other. Will this structure and layout have enough heat dissipation to run passive? I really want to avoid fans or other noisy cooling.
I really like these cases but I'm making my own.If your running them at low power then I think they will be acceptable.
This will be used for my computer and with some luck the sub won't be required depending on the speakers. Still i want a clean amp at reasonable price, and to just buy one extra channel is equivalent to the price of a plate amp and i doubt that the sound quality (theoretical at least) is the same.
It is also about simplicity, just to solder one extra channel and drill a few holes to get a top quality amp doesn't sound like a bad deal. What are the main reasons to use a plate amp instead in your perspective?
Thanks, i have also been looking at these cases for some time because i like the clean look and they are fairly cheap compared to any other 19" case i have found.
They have two options, 300mm and 400mm depth so i can get another 100mm of heatsink on each side to increase the power dissipation a bit if required. I hope this is enough otherwise it could be possible to manually mount another heatsink on the backplate or internally if the holes are enough to provide any ventilation without fan.
Hi Guys!
Sorry for not popping in lately, I've been working hard to get the boards finished up and sent off.
They are officially done, and I'll be generating the Gerbers over the weekend. That means the order will be placed Monday, and I will be getting a 1 week turn on the board which puts me about a week behind the original schedule. Sorry for the delay, but I really wanted to make some more measurements on the balanced input amplifier before sending off any boards.
sooo... the low input impedance on the - terminal shouldn't be a problem, and the only downside will be reduced gain if you happen to have a very high output impedance source driving the amp. CMRR is around 87dB and it remains unaffected by source impedance. Distortion is also unaffected.
I tested with both a 50 ohm source and a 1000 ohm source, and performance was identical with the exception of gain which went from about 27dB to about 18dB when the source impedance goes from 50 ohms to 1000 ohms. That means the balanced input scheme gets the green light, and anyone planning to use the amplifier in this fashion should be good to go.
I've also revised the ground scheme to give a little more flexibility without impacting performance. The end user will have a few options with 0R resistors depending of how they plan to implement supplies.
I also measured with a regulated front end, and as you would expect, most of the 60Hz + harmonics noise is drastically reduced or eliminated. Again, I strongly suggest using a separate regulated supply for the front end if you want the best possible performance. I attached an RCF 10" midrange directly to the outputs with the regulated setup (it's 103dB 1W/1m) and I couldn't hear anything with my ear right against it. That sort of performance is exceedingly rare from any power amplifier.
Measurements attached.
Q&A time...
454Casull:
Not really, other than adding a resistor in series with your load. If you want a current output amplifier, this is probably not the correct choice.
coolfox007:
I put you down for 3 full kits (which include the boards) which is what you asked for a few pages back. I know you later asked for four kits, but I don't have enough PCB's.
Pleas confirm that 3 full kits is what you want.
IanAS and maxw:
You guys are still on the waiting list. Ian, you were bumped in favor of someone who wanted full kits. You'll be bumped again for maxw since he too is looking for full kits. I don't mean to be unfair, but preference is given to full kits orders.
Boscoe:
A month is fine, but please don't leave me high and dry when the time comes. I've adjusted your order to be 6 boards and 6 kits as you requested.
ouimetnick:
Prices are listed on the first page of this thread. You're looking at $156 for all the boards and parts for a stereo pair. The GB is currently full but I can put you on the waiting list.
Qrikard:
Very nice cases! The price is pretty fair too. That should be perfect for a stereo 100W/ch setup. Do they have a C/W rating for the sinks?
Cheers,
Owen
Sorry for not popping in lately, I've been working hard to get the boards finished up and sent off.
They are officially done, and I'll be generating the Gerbers over the weekend. That means the order will be placed Monday, and I will be getting a 1 week turn on the board which puts me about a week behind the original schedule. Sorry for the delay, but I really wanted to make some more measurements on the balanced input amplifier before sending off any boards.
sooo... the low input impedance on the - terminal shouldn't be a problem, and the only downside will be reduced gain if you happen to have a very high output impedance source driving the amp. CMRR is around 87dB and it remains unaffected by source impedance. Distortion is also unaffected.
I tested with both a 50 ohm source and a 1000 ohm source, and performance was identical with the exception of gain which went from about 27dB to about 18dB when the source impedance goes from 50 ohms to 1000 ohms. That means the balanced input scheme gets the green light, and anyone planning to use the amplifier in this fashion should be good to go.
I've also revised the ground scheme to give a little more flexibility without impacting performance. The end user will have a few options with 0R resistors depending of how they plan to implement supplies.
I also measured with a regulated front end, and as you would expect, most of the 60Hz + harmonics noise is drastically reduced or eliminated. Again, I strongly suggest using a separate regulated supply for the front end if you want the best possible performance. I attached an RCF 10" midrange directly to the outputs with the regulated setup (it's 103dB 1W/1m) and I couldn't hear anything with my ear right against it. That sort of performance is exceedingly rare from any power amplifier.
Measurements attached.
Q&A time...
454Casull:
Not really, other than adding a resistor in series with your load. If you want a current output amplifier, this is probably not the correct choice.
coolfox007:
I put you down for 3 full kits (which include the boards) which is what you asked for a few pages back. I know you later asked for four kits, but I don't have enough PCB's.
Pleas confirm that 3 full kits is what you want.
IanAS and maxw:
You guys are still on the waiting list. Ian, you were bumped in favor of someone who wanted full kits. You'll be bumped again for maxw since he too is looking for full kits. I don't mean to be unfair, but preference is given to full kits orders.
Boscoe:
A month is fine, but please don't leave me high and dry when the time comes. I've adjusted your order to be 6 boards and 6 kits as you requested.
ouimetnick:
Prices are listed on the first page of this thread. You're looking at $156 for all the boards and parts for a stereo pair. The GB is currently full but I can put you on the waiting list.
Qrikard:
Very nice cases! The price is pretty fair too. That should be perfect for a stereo 100W/ch setup. Do they have a C/W rating for the sinks?
Cheers,
Owen
Attachments
The links are at the bottom of the first post.
http://www.diyaudio.com/forums/atta...e49830-lateral-mosfets-class-ab-worksheet.pdf
http://www.diyaudio.com/forums/atta...e49830-lateral-mosfets-class-ab-worksheet.pdf
Thanks for making me aware of the existence of that nifty "little" chip. Having gone through the datasheet, I really love how NS deviced the MOSFET driver stage. I'm going to have a go at it in the simulator with a discrete arrangement, although I have no doubt that a discrete version would perform worse - the bias diodes for the shunt transistors in each driver rail sit on the same slab of silicone and are tightly thermally coupled. If one's to try this in a discrete setup one can't omit this thermal coupling.
Unfortunately the group buy is already closed, see for example this post, so you will have to go on the waiting list. Owen has the details of course, but FYI.
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