I believe I am in exactly the same situation as you, preiter, as I have No.34 (complementary bipolar) plus a bag of IRF250s which Nelson thoughtfully encouraged me to take. If you PM me, perhaps we can arrange to test all our mosfets together and get closer matching pairs.preiter said:
I'm also curious as to what would be the likely power possible from these 4 pairs per channel comp bipolar versions, as I haven't quite made up my mind what to build from the chassis.
I have built the NP matcher as described and used it to match a big bag of 240/9240 devices. it works well.
Out of a batch of 20, I was able to find several pairs that were within 1-2 numbers of each other. some sets of 3 and probably 3-5 that had numbers just totally out of range.
For an amp where you need 6 devices matched, you are going to need quite a few to choose from to get them within 1-2 numbers of each other. Not sure quite how tight they need to be? If 3-5 numbers from each other is ok, you probably could find that in 20-25 devices.
Zc
Out of a batch of 20, I was able to find several pairs that were within 1-2 numbers of each other. some sets of 3 and probably 3-5 that had numbers just totally out of range.
For an amp where you need 6 devices matched, you are going to need quite a few to choose from to get them within 1-2 numbers of each other. Not sure quite how tight they need to be? If 3-5 numbers from each other is ok, you probably could find that in 20-25 devices.
Zc
When you said that you wanted an amp for each tweeter I was thinking historically. I thought that you wanted a 60 watt tweeter amp for each speaker. , but you want a separate 60 watt amp for each of two tweeters on each speaker, ie 120 watts per channel assigned to the tweeters, since now Linkwitz uses a forward and back facing tweeter.
It seems more likely that your tweeters were running out of excursion not that the amps were clipping. Of course you can make what you want, that's what DIY is all about, and we all want some headroom, but could someone tell me how much power a dome tweeter like that can draw before melting? It just seems weird to me to have 120 watts for the tweeters and 120 for the bass drivers. On the other hand the tweeter amp distortion will be lower, maybe that's what you are after too.
Again, no worries, but shoehorning 2 60 watt class a amps and say, an 80 watt for the mids into that case is like a 200 watt class A amp,, (single ended?) that seems to be a lot of heat to get rid of to "save the MOSFETS"
Variac,
Keep in mind when I wrote about time I clipped the tweeter amps, I was playing some music at concert levels. SPL was about 105-110db(A) peak 8' from the speakers. The midrange amps were clipping too. The Halfers I was using at the time had clip indicator LEDs. (It was Bjork, BTW. I haven't found any other music with such broadband energy. It was an experiment.)
Each Orion tweeter can handle 90w continuous and 200w peak.
I can't do the heat calcs to verify this, but I would expect that the heatsinks can drain off the 530 watts from the power tranny less a bit
going to the speakers. The heatsinks aren't very massive but they have a large surface area and they're black. I would think Nelson designed the case and heatsinks to handle his SE designs. The A5 is one of the efficient ones.
- Eric
Keep in mind when I wrote about time I clipped the tweeter amps, I was playing some music at concert levels. SPL was about 105-110db(A) peak 8' from the speakers. The midrange amps were clipping too. The Halfers I was using at the time had clip indicator LEDs. (It was Bjork, BTW. I haven't found any other music with such broadband energy. It was an experiment.)
Each Orion tweeter can handle 90w continuous and 200w peak.
I can't do the heat calcs to verify this, but I would expect that the heatsinks can drain off the 530 watts from the power tranny less a bit
going to the speakers. The heatsinks aren't very massive but they have a large surface area and they're black. I would think Nelson designed the case and heatsinks to handle his SE designs. The A5 is one of the efficient ones.- Eric
Here is a thread turning out to be rather relevent for some of us here:
http://www.diyaudio.com/forums/showthread.php?postid=1654234#post1654234
I know that AR2 and I are interested in an Xed, Aleph5 JFETed amp. Maybe others with IRF 250's will be interested. From what I have read here maybe also Eric, preiter, tosh, dw8083, and Fast Eddy..
In other words just about everyone might be satisfied with it.
Don't get me wrong though, an F-4 is stilll a great choice, and a lot less trouble to make with the cases the way most of them came.
Mark
http://www.diyaudio.com/forums/showthread.php?postid=1654234#post1654234
I know that AR2 and I are interested in an Xed, Aleph5 JFETed amp. Maybe others with IRF 250's will be interested. From what I have read here maybe also Eric, preiter, tosh, dw8083, and Fast Eddy..
In other words just about everyone might be satisfied with it.
Don't get me wrong though, an F-4 is stilll a great choice, and a lot less trouble to make with the cases the way most of them came.
Mark
I'm not at all sure what I'm interested in. This will be my first discrete transistor amp, so my confidence in adapting circuits is not high.
My test equipment consists of a cheap voltmeter, so something that doesn't require a lot of debugging would be a big plus.
I don't have any experience with different varieties of class-A amp, so I don't have preferences regarding sound. My primary concern is that the design is something that I can get working.
My test equipment consists of a cheap voltmeter, so something that doesn't require a lot of debugging would be a big plus.
I don't have any experience with different varieties of class-A amp, so I don't have preferences regarding sound. My primary concern is that the design is something that I can get working.
I just read a LOT of the Aleph X building thread and the implication is that it isn't the simplest Pass type amp out there (technically that particular board was designed by Grey Rollins mashing up two Pass concepts/designs, with some input from others) Pass has a similar product.
is the Aleph J X'ed? I think not. If so it might be a better starting point? I find that Nelson's designs tend to work well as they are based on projects that must survive in the commercial world..
On the other hand, if lots of us in this area work together on the same design with the same slight mods, matching parts, checking boards, using someones scope (!) that is a HUGE help. Then factor in Nelson's help and Grey, Zen Mod et al and that is a pretty impressive group watching our backs. Especially if all the amps are basically the same..
AND we have the boards it seems, a shame not to use them IF they are not sub-optimal in some way..
I think we need an opinion on this scheme from the Supreme Leader -NP
Mark
is the Aleph J X'ed? I think not. If so it might be a better starting point? I find that Nelson's designs tend to work well as they are based on projects that must survive in the commercial world..
On the other hand, if lots of us in this area work together on the same design with the same slight mods, matching parts, checking boards, using someones scope (!) that is a HUGE help. Then factor in Nelson's help and Grey, Zen Mod et al and that is a pretty impressive group watching our backs. Especially if all the amps are basically the same..
AND we have the boards it seems, a shame not to use them IF they are not sub-optimal in some way..
I think we need an opinion on this scheme from the Supreme Leader -NP
Mark
Say, ya know? Even us old hands need to be reminded about capacitors and higher power supplies.
I was about to fire up my F4 prototype (NP's gracious gift from BAFest) after installing a different transformer, hooked it through the diode bridge and connecting the caps, soldered leads, etc ... well it works! just fine and voltage across the caps is a healthy + / 0 / - 67.1 VDC with no load.
I turned it off .... and out of curiosity measured it again ... ... still hot after three minutes ... ... still hot after ten minutes ... ... now still hot (+/- 50 VDC = greater than 100 volts across the +/- rails !) after twenty minutes ... = good caps! = still too high a voltage to touch ...
As any fan of Uncle Tom Edison will know, any DC voltage above about + 30 volts leaves a very, very nasty burn = branded as a fool forever ... like me.
I was about to fire up my F4 prototype (NP's gracious gift from BAFest) after installing a different transformer, hooked it through the diode bridge and connecting the caps, soldered leads, etc ... well it works! just fine and voltage across the caps is a healthy + / 0 / - 67.1 VDC with no load.
I turned it off .... and out of curiosity measured it again ...
... still hot after three minutes ... ... still hot after ten minutes ... ... now still hot (+/- 50 VDC = greater than 100 volts across the +/- rails !) after twenty minutes ... = good caps! = still too high a voltage to touch ... As any fan of Uncle Tom Edison will know, any DC voltage above about + 30 volts leaves a very, very nasty burn = branded as a fool forever ... like me.
Tosh said:
Whenever you guys want to have a matching party you let me know. We could do it in my studio. I am centrally located in the city for anyone coming from east, north or south Bay and there is plenty of room for all of us. Ideally on the weekend. If this sounds good to you, I suggest who ever wants to participate let me know and I will inform everyone else. That way we could coordinate the date that works for anyone. which is usually hard to do.
So send me an email if you are interested.
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