Yes.
suppose using a 500VA toroid on the KSA, and the total power taken from the transformer for bias and front end supply is 150 watts.
Sout/Snominal= 0.3, which gives around 93% efficiency.
150/0.93~ 161 watts.
Energy loss at 30% output is 11 watts.
A toroidal transformer can deliver twice the nominal power, the power factor can therefore be 2. The efficiency is greatly reduced beyond Sout/Snom= 1, internal losses would become very high and the transformer would have serious heat problems. Fortunately, the output voltage would drop too for a lengthened output period, thereby limiting the output power.
The efficiency lines for a 300VA and a 1000VA toroidal transformer show that the power losses for an output of 150 watts is about the same for both transformers. The graph also shows that using a 160VA transformer on the Krell would not be wise, the efficiency would be too low to deliver enough of the goodies. On a 150 watts class B amplifier it would still be acceptable efficiency wise.
suppose using a 500VA toroid on the KSA, and the total power taken from the transformer for bias and front end supply is 150 watts.
Sout/Snominal= 0.3, which gives around 93% efficiency.
150/0.93~ 161 watts.
Energy loss at 30% output is 11 watts.
A toroidal transformer can deliver twice the nominal power, the power factor can therefore be 2. The efficiency is greatly reduced beyond Sout/Snom= 1, internal losses would become very high and the transformer would have serious heat problems. Fortunately, the output voltage would drop too for a lengthened output period, thereby limiting the output power.
The efficiency lines for a 300VA and a 1000VA toroidal transformer show that the power losses for an output of 150 watts is about the same for both transformers. The graph also shows that using a 160VA transformer on the Krell would not be wise, the efficiency would be too low to deliver enough of the goodies. On a 150 watts class B amplifier it would still be acceptable efficiency wise.
OK, so this has me wondering.
On my first KSA50 I used a single 30-0-30 500vA toroid. On the second one I used two 28-0-28 400vA transformers and seperate bridges, mono block style except all in one case.
I can't hear any difference between them at all. I saw a post where someone used a 1.2KvA transformer and claimed a big improvement in sound. Just where is it that one should hear the difference when beefing up the PSU?
I use old JBL's and they are pretty efficient. It seems to me that the music will get too loud to enjoy, long before I'm taxing the transformers.
What do you think?
Blessings, Terry
On my first KSA50 I used a single 30-0-30 500vA toroid. On the second one I used two 28-0-28 400vA transformers and seperate bridges, mono block style except all in one case.
I can't hear any difference between them at all. I saw a post where someone used a 1.2KvA transformer and claimed a big improvement in sound. Just where is it that one should hear the difference when beefing up the PSU?
I use old JBL's and they are pretty efficient. It seems to me that the music will get too loud to enjoy, long before I'm taxing the transformers.
What do you think?
Blessings, Terry
JBL -ah ha!
Hi still4given
so......you are a JBL-fan. Me to.
A big transformer could feed the ampli with considerably more current. therefor the improvements will be most noticeable when driving low impedance speakers (4 ohms and lower)
If for example driving 2 ohms impedance speakers and your PSU could deliver 28.28V peak in 8 ohm and 2 ohm respectively you will need >14A from PSU. Now, a small toroidal transformer of 160 or 300VA could only deliver 2A or 3.8A DC if not being over stressed.
A 1000VA of 2x28V could deliver at least 13A DC to ampli. But when using a transformer with 28V instead of 30V it will give PSU some improvements in current capability.
Regards 😎
Hi still4given
so......you are a JBL-fan. Me to.
A big transformer could feed the ampli with considerably more current. therefor the improvements will be most noticeable when driving low impedance speakers (4 ohms and lower)
If for example driving 2 ohms impedance speakers and your PSU could deliver 28.28V peak in 8 ohm and 2 ohm respectively you will need >14A from PSU. Now, a small toroidal transformer of 160 or 300VA could only deliver 2A or 3.8A DC if not being over stressed.
A 1000VA of 2x28V could deliver at least 13A DC to ampli. But when using a transformer with 28V instead of 30V it will give PSU some improvements in current capability.
Regards 😎
Hi,
I have finished (well, almost) one of my 2 KSA-50 monoblocks. I didn't plug it in, since I am still missing the driver board heatsink, and I am not sure if the signal ground should go to the amplifier board, or straight to the star ground.
Here are some pics of the KSA-50:
Paul
I have finished (well, almost) one of my 2 KSA-50 monoblocks. I didn't plug it in, since I am still missing the driver board heatsink, and I am not sure if the signal ground should go to the amplifier board, or straight to the star ground.
Here are some pics of the KSA-50:
Paul
Attachments
And finally, this is the back, also done by Front Panel Express. The two empty holes are meant for 1/8 jacks for a trigger input and an output, but that will only be done after I get it powered up.
If anyone sees anything that looks wrong, please let me know.
Thanks.
Paul
If anyone sees anything that looks wrong, please let me know.
Thanks.
Paul
Attachments
Great work Paul! Why not just mount your drivers and bias sense to the bottom of the chassis?? The chassis is PLENTY of heat sinking for them. Solder them to the driver board so they come down from the bottom of the PCB and towards the edge of the PCB. This way you have access to the mounting holes in the devices.
Mark
Mark
Re: 6000?
I was not getting emails.... just came to visit the site and saw 3 pages more than I left ;-)
lgreen said:
I was not getting emails.... just came to visit the site and saw 3 pages more than I left ;-)
Thanks Mark.
The drivers mounting you suggest is a good idea, I just wasn't sure if I would have enough heat dissipation. I'll take the driver board out tonight, and mount them the way you suggest.
That should also avoid the headache of adding another heatsink in that tiny space 🙂
Paul
The drivers mounting you suggest is a good idea, I just wasn't sure if I would have enough heat dissipation. I'll take the driver board out tonight, and mount them the way you suggest.
That should also avoid the headache of adding another heatsink in that tiny space 🙂
Paul
Excellent work Paul, I really look forward to seeing them finished. Those power resistors look familiar. 😉
Mark !
Wandering if you receive e-mails from me or a spam filter is just throwing them away in to the "basket"? Do you have a more reliable e-mail address?
Looking forward to hear from you.
Regards 😎
Wandering if you receive e-mails from me or a spam filter is just throwing them away in to the "basket"? Do you have a more reliable e-mail address?
Looking forward to hear from you.
Regards 😎
Hi Floodttroem,
You have e-mail! I do weekly service trips on occassion (more than not lately) and on this last one had no e-mail acccess with over 200 to reply to do when I got back
. That takes some time!
Mark
You have e-mail! I do weekly service trips on occassion (more than not lately) and on this last one had no e-mail acccess with over 200 to reply to do when I got back
. That takes some time!Mark
MJ15003/4-To 3 mounting idea:
Hi folks
I thought it could be interesting to some of you to share an idea for how to mount To-3 devices on heat sink for to not get a to small internal space inside amp. for transformer, caps and driver boards.
I should appreciate any comments what so ever to this issue.
Regards 😎
Hi folks
I thought it could be interesting to some of you to share an idea for how to mount To-3 devices on heat sink for to not get a to small internal space inside amp. for transformer, caps and driver boards.
I should appreciate any comments what so ever to this issue.
Regards 😎
"For Low Distortion Complementary Designs"
Thats what OnSemi says about MJ15003/4. Also this transistor pair has a much better hfe spec than the MJ15024/25. (15 to 50 min). But MJ15024/25 could withstand higher voltage rails in a high power amp design like those intended for PA applications.
This is OnSemi Data sheet specs. But I have no experience by my own to those MJ15024/25.
Regards 😎
Thats what OnSemi says about MJ15003/4. Also this transistor pair has a much better hfe spec than the MJ15024/25. (15 to 50 min). But MJ15024/25 could withstand higher voltage rails in a high power amp design like those intended for PA applications.
This is OnSemi Data sheet specs. But I have no experience by my own to those MJ15024/25.
Regards 😎
Hi Flod,
try a 50 by 50 by 6mm aluminium angle.
Mount one face with bolts and heatsink compound to the heatsink. The other face can be fixed as your pdf showed to the PCB and To3 inserted from the other side.
try a 50 by 50 by 6mm aluminium angle.
Mount one face with bolts and heatsink compound to the heatsink. The other face can be fixed as your pdf showed to the PCB and To3 inserted from the other side.
