400W into 8ohm speakers:
400W into 8r0 requires an output of 80Vpk at the speaker terminals.
400W into an 8ohm speaker requires a peak current of at least double what an 8r0 resistor will draw and doing this while the voltage holds up near the 8r0 loading peak output voltage. Following Cordell's interviews, I changed my design method to require 3times the 8r0 peak current.
Allowing for an output voltage of -1dBv ref 8r0, we need 89% of 80Vpk and current equivalent to driving a load of between 2r7 and 4r. If you choose 4r then the peak outputs should be 71.3Vpk while delivering 17.8Apk.
For a BJT output stage, I would allow a loss through the amplifier of ~3V and assuming a 5V sag in PSU when delivering 400W then the PSU needs to be ~8V above that quoted peak value, i.e. +-88Vdc using at least 600VA transformer/channel and at least +-20mF/channel with >=100Vdc caps.
For source follower mosFET output stage, I would add 3 to 5V to that 88Vdc target, i.e. ~ +-92Vdc. Now, you will need to check that 100V capacitors can satisfy worst case operation.
400W into 8r0 requires an output of 80Vpk at the speaker terminals.
400W into an 8ohm speaker requires a peak current of at least double what an 8r0 resistor will draw and doing this while the voltage holds up near the 8r0 loading peak output voltage. Following Cordell's interviews, I changed my design method to require 3times the 8r0 peak current.
Allowing for an output voltage of -1dBv ref 8r0, we need 89% of 80Vpk and current equivalent to driving a load of between 2r7 and 4r. If you choose 4r then the peak outputs should be 71.3Vpk while delivering 17.8Apk.
For a BJT output stage, I would allow a loss through the amplifier of ~3V and assuming a 5V sag in PSU when delivering 400W then the PSU needs to be ~8V above that quoted peak value, i.e. +-88Vdc using at least 600VA transformer/channel and at least +-20mF/channel with >=100Vdc caps.
For source follower mosFET output stage, I would add 3 to 5V to that 88Vdc target, i.e. ~ +-92Vdc. Now, you will need to check that 100V capacitors can satisfy worst case operation.
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Last I checked "stereo" was two channels, so yes
I remember reading somewhere someone wanted stereo set or 4 channels just wanted to make sure it wasn't you!
Me! I'm after a complete stereo set
Understand your excitement but few members already in the Que for refused boards on this GB !
Let the Owen manage the list on the basis first come first serve I think is fair ?
Hi Guys!
It was a tonne of work getting the boards out last week, so I took a little break from the whole project which is why I haven't been on for a little bit.
The boards went out last week, and should be in sometime this week depending on how quick they ship them, and how fast they get here. I made a few minor changes to the way the Mute circuit is implemented, so I'll post up a screenshot of the finished board this evening so people have a final reference if they want to plan out their cases.
Another little bit of good news is that I ordered extra panels since the the price breaks worked out such that it wasn't really going to cost too much more for the extra panels over the 30 I originally intended to order. In the end I wound up with 50 panels, which is a total of 200 amplifier PCB's.
On that note, I'm going to re-open the group buy until the rest of the boards are gone.
Anyone who signs up from this point on will have to wait a little while longer for their boards since I plan on shipping out the original 120 boards first. The exception to this is if you already have an order and want to increase it. In that case you'll maintain priority.
I would also like to emphasize that you can add parts kits to any board order without a problem. I'll let people know when I'm closing the parts kit signup, which will likely be in two weeks.
Could everyone who was on the waiting list please re-confirm your order here before I add you to the real list? Just put up a post with exactly what you want, and I'll add you to the list.
Cheers,
Owen
It was a tonne of work getting the boards out last week, so I took a little break from the whole project which is why I haven't been on for a little bit.
The boards went out last week, and should be in sometime this week depending on how quick they ship them, and how fast they get here. I made a few minor changes to the way the Mute circuit is implemented, so I'll post up a screenshot of the finished board this evening so people have a final reference if they want to plan out their cases.
Another little bit of good news is that I ordered extra panels since the the price breaks worked out such that it wasn't really going to cost too much more for the extra panels over the 30 I originally intended to order. In the end I wound up with 50 panels, which is a total of 200 amplifier PCB's.
On that note, I'm going to re-open the group buy until the rest of the boards are gone.
Anyone who signs up from this point on will have to wait a little while longer for their boards since I plan on shipping out the original 120 boards first. The exception to this is if you already have an order and want to increase it. In that case you'll maintain priority.
I would also like to emphasize that you can add parts kits to any board order without a problem. I'll let people know when I'm closing the parts kit signup, which will likely be in two weeks.
Could everyone who was on the waiting list please re-confirm your order here before I add you to the real list? Just put up a post with exactly what you want, and I'll add you to the list.
Cheers,
Owen
I forgot to ask Owen if he will be willing to sell me some more transistors as well.
I'd prefer to parallel more than two output transistors in such a design going to higher power. Easier to ensure long term performance of such a worthy design. ANd doesn't hurt for cranking out the current from time to time either.
On the switching power supply front I would definitely be interested if they incorporated the refinements that Owen mentioned. Fixes many of the issues I have had looking at those supplies.
I'd prefer to parallel more than two output transistors in such a design going to higher power. Easier to ensure long term performance of such a worthy design. ANd doesn't hurt for cranking out the current from time to time either.
On the switching power supply front I would definitely be interested if they incorporated the refinements that Owen mentioned. Fixes many of the issues I have had looking at those supplies.
