My first approximation is in this way. If I see the left channel only, I may have a diff pair forming two sides. Through the one side, 2.272A flows in-between the rail voltages of +15 and -15V. Therefore, 2.272 x (15+15) = 68.16 watts to the one side. Then, 68.16 x 2 = 136.32 watts to the one channel.macka said:
What is your heat sink capacity per channel?
What is the heat sink temperature?
Bloody hot?
JH
JH,
Your calc is as mine.
Okay,
My heatsink per channel is 0.25 c per watt, A Conrad twin flange 150mm x 300mm x 48mm.
The temp on the heatsink was boody hot I reakon, mid to high 50's.
34 watts per devcie @ 55-58 could be pushing the reliability .
Some may think that to reduce the bias will reduce potential class A performance, a small say 25 % reduceion on burnt or waisted bias should not be a real issue and will reduce ripple and noise.
Alternatively I could double up on the power fets and lower the junction temp as a safe guard, and up the source resisters to 0.47 ohms. This should als0 improve the transconductance ands hence bottom end control a bit.
Ian
Your calc is as mine.
Okay,
My heatsink per channel is 0.25 c per watt, A Conrad twin flange 150mm x 300mm x 48mm.
The temp on the heatsink was boody hot I reakon, mid to high 50's.
34 watts per devcie @ 55-58 could be pushing the reliability .
Some may think that to reduce the bias will reduce potential class A performance, a small say 25 % reduceion on burnt or waisted bias should not be a real issue and will reduce ripple and noise.
Alternatively I could double up on the power fets and lower the junction temp as a safe guard, and up the source resisters to 0.47 ohms. This should als0 improve the transconductance ands hence bottom end control a bit.
Ian
Yeah haaaaaaaaaaa!!!
... just got back from a small hybernation - almost finished by x-bosoz while at it. Was so busy that I havn't looked at this tread for TWO WHOLE DAYS!!!
I consider myself a student to most what is said here and I find it really awesome - such a bunch of brainy people could only make things SOUND BETTER...
What a surprise to find out that my guess was closest. Mr Pass, I'll pay the shipping (if it's going to be heavy
). Times like this when I wish I was closer.......
Vossie
... just got back from a small hybernation - almost finished by x-bosoz while at it. Was so busy that I havn't looked at this tread for TWO WHOLE DAYS!!!
I consider myself a student to most what is said here and I find it really awesome - such a bunch of brainy people could only make things SOUND BETTER...
What a surprise to find out that my guess was closest. Mr Pass, I'll pay the shipping (if it's going to be heavy
). Times like this when I wish I was closer.......Vossie
Yes,
The freight on any solid metal object coming out the front door from this outfit is gona be Large .
These folks must be strong, they just don't understand the effect of gravity, I mean even the pre's are a body builders nightmare.
Perhaps this is why Mrs Pass (a fitness trainer we understand) has clients at the office at Foresthill.
Watch out for those muscles boys!!!
If you intend paying the freight bill cod, I would pass for a poster of the Diva if you live a long way away, you'll love it, Muhuhuhuhu.
Ian
The freight on any solid metal object coming out the front door from this outfit is gona be Large .
These folks must be strong, they just don't understand the effect of gravity, I mean even the pre's are a body builders nightmare.
Perhaps this is why Mrs Pass (a fitness trainer we understand) has clients at the office at Foresthill.
Watch out for those muscles boys!!!
If you intend paying the freight bill cod, I would pass for a poster of the Diva if you live a long way away, you'll love it, Muhuhuhuhu.
Ian
unusual question:
Hi all,
So we want to keep the chassis at 50 degrees C. How hot can the chokes and transformer go? I find that my power transformer (separated from chassis and sealed in a sand/resin filled factory metal enclosure) gets almost as hot as my chassis; 10 second touch on the transformer, and an uncomfortable 10 seconds on the chassis. I can't reach the chokes, but they're probably plenty warm as well. How hot to the touch can the chokes and transformer operate?
Thanks,
John
Hi all,
So we want to keep the chassis at 50 degrees C. How hot can the chokes and transformer go? I find that my power transformer (separated from chassis and sealed in a sand/resin filled factory metal enclosure) gets almost as hot as my chassis; 10 second touch on the transformer, and an uncomfortable 10 seconds on the chassis. I can't reach the chokes, but they're probably plenty warm as well. How hot to the touch can the chokes and transformer operate?
Thanks,
John
Re: unusual question:
JH
If the transformers and the chokes satisfy the required current rating, I forget their operating temperatures. Only concern might be the electrolytic capacitors placed near by because it is well known that electrolytic capacitor's life is mainly dependant upon its operating temperature. My rule of thump is keeping the capacitor¡¯s operating temperature less than 1/2 of the rated one (normally 85 degC).carpenter said:
JH
John,
Take a look at Plitron's site. They specify they design for for a 40deg rise over ambient at full load. This is also dependent on duty cycle but I don't believe this will have as great a role in audio as in other apps (like welding).
http://www.plitron.com/pages/technote.htm
Take a look at Plitron's site. They specify they design for for a 40deg rise over ambient at full load. This is also dependent on duty cycle but I don't believe this will have as great a role in audio as in other apps (like welding).
http://www.plitron.com/pages/technote.htm
I think you might be using an under-rated transformer if it is getting that hot. I tried checking a few other sites to see if the design to similar specs as Plitron and was not able to find any other thermal specs. I would guess that their design considerations would not be much different. Do you have access to a different transformer for testing purposes? Maybe just an EI with a higher rating to see if it has the same impact. Is your transformer case-mounted? Some of those potted transformers are designed to be mounted for sinking like a bridge rectifier.
My transformer is call a "buck boost"
It's designed for indoor/outdoor use; hence the painted steel casing. It's rated at 500 v/a 16v/16v. With the choke filter and the stereo load it's voltage ends up being 11 volts per rail per board. I run the transformer through two dual bridge networks; one pair of bridges per channel.
It's designed for indoor/outdoor use; hence the painted steel casing. It's rated at 500 v/a 16v/16v. With the choke filter and the stereo load it's voltage ends up being 11 volts per rail per board. I run the transformer through two dual bridge networks; one pair of bridges per channel.
I have one of those as well, a little higher voltage though (60VAC). From a remote radio transmitter station the Navy decommissioned. I bet yours is painted machinery grey too. Anyway, It certainly sounds up to the job, rating wise. How much a drop in voltage does it go through between loaded and unloaded? I drop of more than a volt that increases to a couple as the heat goes up could mean some bad wiring (cracks in solid wiring start acting as resistors if there more than a few). Test the resistance through(not across) each of the windings when its cold then again after it heats up. I have tried testing the insulation resistence of a transformer before and found one that would start to short out to ground as it warmed up. I used a megger to test it, something not very common in the DIY community. I can't really think of any other possible problems if your boards are stable and your transistors are behaving.
Grey told me that he was leaving the forum, for good.
So I don't know that it matters.
Whoever didn't like Grey's wordy posts and spent the days dotting all the i's and crossing all the t's on what he was saying should feel free to step up to the plate and provide, for starters, the tube X-preamp that I, a few other people here, have been waiting for.
So I don't know that it matters.
Whoever didn't like Grey's wordy posts and spent the days dotting all the i's and crossing all the t's on what he was saying should feel free to step up to the plate and provide, for starters, the tube X-preamp that I, a few other people here, have been waiting for.
Pass DIY Addict
Joined 2000
Paid Member
Yes, it's a shame, but.......
We're all grown-ups here. If we post in such a way that a moderator thinks we need a time out then we can either act mature and take the time out to ponder and understand all sides, or, we can simply grab our marbles and go home. Frankly, I think Grey did what he wanted to do. Don't we all? I don't think he was "chased" away. Part of the maturing process is learning to deal with group situations. It isn't always fun, but in the end it is rewarding.
John
We're all grown-ups here. If we post in such a way that a moderator thinks we need a time out then we can either act mature and take the time out to ponder and understand all sides, or, we can simply grab our marbles and go home. Frankly, I think Grey did what he wanted to do. Don't we all? I don't think he was "chased" away. Part of the maturing process is learning to deal with group situations. It isn't always fun, but in the end it is rewarding.
John
Grey's gone!?! Man, that really sucks. Even as a late-comer, I feel that Grey was THE most prolific contributor to the audio side of this forum. I am very sorry to hear he is gone. Anyone who had problems with technical posts needs to put up or shut up. Even my limited knowledge can recognize the difference between a legitimate critical post of his design and outright attempt at instigating an arguement to satisfy the challengers insecurities. I felt his "Stranger" posts were a great way to deal with people who haven't thick enough skin to take his suggestions or felt their unfounded bitching went unheard. Granted, Grey wasn't innocent nor is he all-knowing, and I feel his leaving doesn't speak much for his own maturity. Unfortunately, he did spend a lot of time defending his AlephX design from immature attacks and silly attempts at dragging the thread through the mud. Sure, everyone has a right to contribute an input, but build the thing first, try your variations and make an honest post. Don't attack the man. Grey was very generous for allowing the rest of the people in this forum to benefit from his hard work and inventiveness. I sorry to vent but I have been growing tired 
of reading posts of people whining about crap. Hey, OT posts can be humourous and fun but promoting a negative environment doesn't do anyone any good.
of reading posts of people whining about crap. Hey, OT posts can be humourous and fun but promoting a negative environment doesn't do anyone any good.
We'll have to carry on.....
Grey gave us some wonderful gifts. With or without him, we must carry on. Every time I listen to the AX I smile and think of my good fortune and truly enjoy the blessings of having participated with this forum. This is an excellent place to grow. Mind you, I'm a carpenter not an EE. If I can grow, anybody can.
It doesn't make me feel better to blame someone for Grey's leaving. I choose not to do so. In life, we do as we please; that is unless you're placed in a situation beyond your control. That's another topic.
Grey gave us some wonderful gifts. With or without him, we must carry on. Every time I listen to the AX I smile and think of my good fortune and truly enjoy the blessings of having participated with this forum. This is an excellent place to grow. Mind you, I'm a carpenter not an EE. If I can grow, anybody can.
It doesn't make me feel better to blame someone for Grey's leaving. I choose not to do so. In life, we do as we please; that is unless you're placed in a situation beyond your control. That's another topic.