ZM, I have a need smaller summer amp, a mini version. What is the lowest rail voltage you would recommend? I'm afraid that I do not know what voltage the cascode needs.
On second thought an Xj is probably best as a large amp. Please do bother to take the time to work out how to politely tell me how dumb this idea is.
cascodes (one being for input LTP ,second one for emiter follower in-between LTP and OS) aren't in least amount critical for adaptive biasing
though , no matter what amount of outputs one intend to use , I think that lowest practical figure for dissipation is around 200W per channel .
Reason is simple - Aleph OS is strict A class jobbie (unable to do Klunk!, to transcend in AB class) , so even with smallest rails (say 18Vdc , lower than that starting to deal with nasty capacitances in output mosfets) there is finite practical minimal Iq ,just to avoid situation of Iq being grossly limiting factor for maximal power
as far as I'm able to comprehend , that would be +/-18Vdc rails , 5 mosfets per quadrant (so 20 per channel) , source resistors 1R , Iq aroundish 500mA per vertical pair, sum Iq aroundish 5A
thingie pretty much able to squeeze out 65W/8R and 40W/4R
hope I worked enough , to politely say how dumb you are
though , no matter what amount of outputs one intend to use , I think that lowest practical figure for dissipation is around 200W per channel .
Reason is simple - Aleph OS is strict A class jobbie (unable to do Klunk!, to transcend in AB class) , so even with smallest rails (say 18Vdc , lower than that starting to deal with nasty capacitances in output mosfets) there is finite practical minimal Iq ,just to avoid situation of Iq being grossly limiting factor for maximal power
as far as I'm able to comprehend , that would be +/-18Vdc rails , 5 mosfets per quadrant (so 20 per channel) , source resistors 1R , Iq aroundish 500mA per vertical pair, sum Iq aroundish 5A
thingie pretty much able to squeeze out 65W/8R and 40W/4R
hope I worked enough , to politely say how dumb you are
Thanks ZM. Such a complete effort from you deserved a least a witty reply from me. I thought and thought and thought, but I think my voltage is a too low. I couldn't think of anything. Still dumb but I now know the right questions and answers. I used to know this stuff but LTSpice has been doing my math for so long I seem to have forgotten how to do it myself. I have to do a little homework to figure out how to work it out myself, but with the answers in hand this will be easier. Time to pull out Bob Cordell's book and do some reading.
what Donut rails you have ?
usually , multiplying them with 1.25 will put you in ballpark of resulting DC rails
we can go from there
regarding LTSpice , I'm often relying on it too , but I'm cozy enough only with sims already proven in vivo
this thing (BJX) I simulated from here to Tajikistan and back , confirmed with measurements, so it's easy to change few thing here and there and have recipe for new iteration
usually , multiplying them with 1.25 will put you in ballpark of resulting DC rails
we can go from there
regarding LTSpice , I'm often relying on it too , but I'm cozy enough only with sims already proven in vivo
this thing (BJX) I simulated from here to Tajikistan and back , confirmed with measurements, so it's easy to change few thing here and there and have recipe for new iteration
I am really just at the thinking stage. I think I need a low power amp for the two months of summer that is too hot. I was thinking about a mini Aleph J, but cascodes have been tempting my interest for sometime. It looks like a mini Aleph J or Babelfish J with 18V (was 15V) rails will fit that need. We do get 3 very cold months and I will save the X format for a big winter amp. Always need to have a few more amps. My real problem will be justifying it as I have been convinced, in part by some posts by some Serbian guy, to build some Altec (GPA) 604 speakers and they are very efficient. I may have to organize a neighbourhood street party to justify them. I will move my summer amp questions over to your Babelfish J thread.
if that's the case (Sissy Altecs) , you don't need big power/big dissipation amp
though - if you enjoy in building , that's reason good enough per se 🙂
I agree , there is something seductive in big cones backed up with special big amps
though - if you enjoy in building , that's reason good enough per se 🙂
I agree , there is something seductive in big cones backed up with special big amps
Wooo !!!
Zen, congratulations .. great job .. super X !!! I do not know if I have the skills to achieve but, if I wanted to try to realize for myself; can you lure me to the pcb? I had made a toroidal 1000w 2x18 and I have 16 capacitors 47000uf 63v coming from an Aleph 2 .. I could reuse here? thank you 🙂🙂
Zen, congratulations .. great job .. super X !!! I do not know if I have the skills to achieve but, if I wanted to try to realize for myself; can you lure me to the pcb? I had made a toroidal 1000w 2x18 and I have 16 capacitors 47000uf 63v coming from an Aleph 2 .. I could reuse here? thank you 🙂🙂
I did replied in X thread , but anyway , pasted here :
- first you need to be 158% sure that , even if you aren't able in this very moment , you'll work to be able to make them
only then you can proceed
with these changes I made in schematic , setting procedure is so simple , that 7-year old can do it and nothing is even remotely critical
however , assembly is still thing for either 77 yrs old , or 27-37 years old, but with very strong Zen
if you're sure that you need 100W/8R , I told you what's the price - 350W of heat per channel
I already started on pcbs for smaller iteration - having "just" 20 mosfets per channel , not 40 as shown in my blog/thread , possible to squeeze in damn big case , as stereo amp
in any case , I can order pcbs if anyone want them , but they can't be cheap (single number quantity) nor I have intention to keep them cheap ..... knowing that anyone who buys them from me will chip hardly in my next year's time , rightfully demanding and expecting support from me
- first you need to be 158% sure that , even if you aren't able in this very moment , you'll work to be able to make them
only then you can proceed
with these changes I made in schematic , setting procedure is so simple , that 7-year old can do it and nothing is even remotely critical
however , assembly is still thing for either 77 yrs old , or 27-37 years old, but with very strong Zen
if you're sure that you need 100W/8R , I told you what's the price - 350W of heat per channel
I already started on pcbs for smaller iteration - having "just" 20 mosfets per channel , not 40 as shown in my blog/thread , possible to squeeze in damn big case , as stereo amp
in any case , I can order pcbs if anyone want them , but they can't be cheap (single number quantity) nor I have intention to keep them cheap ..... knowing that anyone who buys them from me will chip hardly in my next year's time , rightfully demanding and expecting support from me
I'm finishing up building my new speaker., Ekta Grande, that year 4 ohms of impedance, x I was looking for amplifying with high power, do not want to do by amping, and I have the hifi2000 5u x 400, in which I mounted my previous aleph 2I did replied in X thread , but anyway , pasted here :
- first you need to be 158% sure that , even if you aren't able in this very moment , you'll work to be able to make them
only then you can proceed
with these changes I made in schematic , setting procedure is so simple , that 7-year old can do it and nothing is even remotely critical
however , assembly is still thing for either 77 yrs old , or 27-37 years old, but with very strong Zen
if you're sure that you need 100W/8R , I told you what's the price - 350W of heat per channel
I already started on pcbs for smaller iteration - having "just" 20 mosfets per channel , not 40 as shown in my blog/thread , possible to squeeze in damn big case , as stereo amp
in any case , I can order pcbs if anyone want them , but they can't be cheap (single number quantity) nor I have intention to keep them cheap ..... knowing that anyone who buys them from me will chip hardly in my next year's time , rightfully demanding and expecting support from me
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this one is having 100W/8R and 80W/4R
smaller one (5 mosfets per quadrant , 20/channel/heatsink ) can be approx. 65W/6R and 40W/4R , with 200W of heat/channel
nature of the Beast , not being able to go Klunk! in AB class
even with 2 cases as yours , you can't cover 350W per case
not even with 5U/500 from Modushop
so - either custom made ones , or going to some amp capable of AB class function , tossing them (channels) in 2pcs of 5U/400
smaller one (5 mosfets per quadrant , 20/channel/heatsink ) can be approx. 65W/6R and 40W/4R , with 200W of heat/channel
nature of the Beast , not being able to go Klunk! in AB class
even with 2 cases as yours , you can't cover 350W per case
not even with 5U/500 from Modushop
so - either custom made ones , or going to some amp capable of AB class function , tossing them (channels) in 2pcs of 5U/400
then I have to make a top range AB with many muscles on 4 ohms or do the amp with maybe a 30-50w on the medium high and an AB on the middlebass ... any suggestions?🙂
of amps known around .....
mucho cojones: BA3 Balanced , uP amp (Frenchy one) ..... from top of my head
of smaller ones ...... any of (bigger) Alephs (make it as J) , bigger F5 .....
mucho cojones: BA3 Balanced , uP amp (Frenchy one) ..... from top of my head
of smaller ones ...... any of (bigger) Alephs (make it as J) , bigger F5 .....
Zen Mod,
would you please advise about dissipation capabilities of Modushop heatsinks 5U/400 (2 pcs of 210 x 200 each side) and 5U/500 (2 pcs of 210 x 250 each side) - what Is nominal power per channel that they do without problem
eyeballing ...... taking in account previous experience with several 4U/400 and one 5U/400 ....... say that 5U/400 is good up to 110-120W , while 5U/500 is good for 140W per side maybe even few watts more