I believe "cascoding" is doubling, i'm still trying to wrap my head around AlephX let alone AlephJX myself, so keep a pound of salt handy. By doing this, you're able to increase the input stage bias to properly drive the outputs. It's been done, attached is the scheme used by Graeme aka 'gl'. Not sure if its an easy task with Peter's boards (if that's what you're using), but its doable. Everything you've ever wanted to know is found in the Aleph-X builder's thread sticky at the top of this forum....if your eyes glaze over, no worries, I've been around here awhile and I'm still not all the way through.
-john
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Hi a.wayne
What are you trying to achieve?
What version do you want to build?
I think you will be best served by sticking to the original Aleph J and using 3 output pairs, unless of course you have your heart set on the Aleph JX.
The JX really is an experimental design and it appears no one has built it yet and you are already looking at trying to modify an unproven design.
You are realy asking for trouble. That is ok of course as long as you like a challenge and are prepared to have quite a few headaches along the way.
What are you trying to achieve?
What version do you want to build?
I think you will be best served by sticking to the original Aleph J and using 3 output pairs, unless of course you have your heart set on the Aleph JX.
The JX really is an experimental design and it appears no one has built it yet and you are already looking at trying to modify an unproven design.
You are realy asking for trouble. That is ok of course as long as you like a challenge and are prepared to have quite a few headaches along the way.
Hello ,
I was looking at the Aleph J and took a look at the X . TO be Honest there is so much Aleph going around it get s a bit confusing to follow ..
I mean what is good better ,best , Aleph 1 ,🙂 Aleph f1,f2,f,3 ,f4,f5, , first watt second watt , 🙂 J with an X , maybe i will start a new thread to get feedback on the different builds , likes and dislikes etc ..
The standard won't work for me as I'm looking for " an amp so simple, even a cave man could build it" and my requirements are
75watt @ 8 ohm
150watt @ 4 ohm
300 watt @ 2 ohm
600 watt @ 1 ohm
Has to be stable @ 1 ohm ( yes , i 'm doing a likkle welding 🙂 )
Any info thrown my way would be absorbed ....
and appreciated .......
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Do you realy need 600W @ 1 Ohm?
I can't remember the specifics. I will have to check. But here is a guess, I think this design can output 1.5 x the bias current
I can't remember the specifics. I will have to check. But here is a guess, I think this design can output 1.5 x the bias current
Hello ,
I was looking at the Aleph J and took a look at the X . TO be Honest there is so much Aleph going around it get s a bit confusing to follow ..
I mean what is good better ,best , Aleph 1 ,🙂 Aleph f1,f2,f,3 ,f4,f5, , first watt second watt , 🙂 J with an X , maybe i will start a new thread to get feedback on the different builds , likes and dislikes etc ..
The standard won't work for me as I'm looking for " an amp so simple, even a cave man could build it" and my requirements are
75watt @ 8 ohm
150watt @ 4 ohm
300 watt @ 2 ohm
600 watt @ 1 ohm
Has to be stable @ 1 ohm ( yes , i 'm doing a likkle welding 🙂 )
Any info thrown my way would be absorbed ....
Most these amps are class a, 600 watts is not practical unless your water cooling and have 2kva transformers. Why dont you try a class ab amp?
just for fun I tried a config for an aleph x that can deliver 600 watts into 1 ohm on the spreadsheet that was posted on this forum, its one big amp🙂
Oh the fet count is a bit on the low side try 48 and it gets dissipation down to 32 watts per fet. I dare you🙂
Oh the fet count is a bit on the low side try 48 and it gets dissipation down to 32 watts per fet. I dare you🙂
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What about the wiring?
I am assuming you mean 600 Watts rms per channel. That is 1200Watts peak per channel.
You are looking at around 30A idling through your power supply wiring.
Assuming the Aleph J is capable of putting out a maximum of 1.5 x bias current then you need a bias current of 23 Amps.
To give you 75 Watts into 8 Ohms you need somewhere around +/- 35 Volt rails.
So that comes to around 1600W of heat to be dissippated.
So you are going to need 16 Conrad heatsinks per channel (the biggest ones) and at least a 3.2kVA transformer per channel.
Go For It
I am assuming you mean 600 Watts rms per channel. That is 1200Watts peak per channel.
You are looking at around 30A idling through your power supply wiring.
Assuming the Aleph J is capable of putting out a maximum of 1.5 x bias current then you need a bias current of 23 Amps.
To give you 75 Watts into 8 Ohms you need somewhere around +/- 35 Volt rails.
So that comes to around 1600W of heat to be dissippated.
So you are going to need 16 Conrad heatsinks per channel (the biggest ones) and at least a 3.2kVA transformer per channel.
Go For It
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Wrong
P=vi
Prms= Vrms x Irms = (Vpk/1.414) x (Ipk/1.414) = (Vpk x Ipk)/2 = Peak Power/2
Since 1.414 x 1.414 =2
Transposing then gives:
Peak Power = 2 x rms power
P=vi
Prms= Vrms x Irms = (Vpk/1.414) x (Ipk/1.414) = (Vpk x Ipk)/2 = Peak Power/2
Since 1.414 x 1.414 =2
Transposing then gives:
Peak Power = 2 x rms power
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I think its Pavg=Vrms X Irms. Pavg is different Prms, but Prms is not really valid.
You still havent shown how I got 2 billion PMPO🙂
You still havent shown how I got 2 billion PMPO🙂
A.Wayne,
The standard Aleph J which If I am not wrong here was an Aleph 3 which Nelson Pass changed to JFET frontend and tweaked a few minor details. This design has always been a sweet spot in the Aleph line and should sound very good in the stock J configuration. Peter added the X layout for us to use and experiment with. It is a proven design but has not been implemented in the J as yet.
For your load requirements I believe you might consider using an output transformer on the 2 and 1 ohm loads. The standard wall outlet will not even come close to SAFELY handling the amp load you are trying to use in class A. There currently is a thread going in the First Watt F5 thread which is discussing this same load on the house wiring. Things are trying to catch on fire. I have a Leach amp design which I routinely run on 2 ohms which has 10 output devices but is not biased in class A after about 1 amp output. It gets a little warm at times but has not let out the smoke yet.
Look through the owner and service manuals at Pass labs and see which designs are rated for this kind of power and try to build one more suited to your own requirements. I think any of the Pass amps will be a great amp project.
In one of Nelson's reviews he is quoted as saying it will handle 2 ohms and not even burp. That does not mean it will not get very hot.
Tad
The standard Aleph J which If I am not wrong here was an Aleph 3 which Nelson Pass changed to JFET frontend and tweaked a few minor details. This design has always been a sweet spot in the Aleph line and should sound very good in the stock J configuration. Peter added the X layout for us to use and experiment with. It is a proven design but has not been implemented in the J as yet.
For your load requirements I believe you might consider using an output transformer on the 2 and 1 ohm loads. The standard wall outlet will not even come close to SAFELY handling the amp load you are trying to use in class A. There currently is a thread going in the First Watt F5 thread which is discussing this same load on the house wiring. Things are trying to catch on fire. I have a Leach amp design which I routinely run on 2 ohms which has 10 output devices but is not biased in class A after about 1 amp output. It gets a little warm at times but has not let out the smoke yet.
Look through the owner and service manuals at Pass labs and see which designs are rated for this kind of power and try to build one more suited to your own requirements. I think any of the Pass amps will be a great amp project.
In one of Nelson's reviews he is quoted as saying it will handle 2 ohms and not even burp. That does not mean it will not get very hot.
Tad
The standard won't work for me as I'm looking for " an amp so simple, even a cave man could build it" and my requirements are
75watt @ 8 ohm
150watt @ 4 ohm
300 watt @ 2 ohm
600 watt @ 1 ohm
Has to be stable @ 1 ohm ( yes , i 'm doing a likkle welding 🙂 )
Any info thrown my way would be absorbed ....
Ok you say you want 75W @ 8 Ohm. That is achievable.
However you need to be a bit more realistic in your requirements. I am fairly sure you dont listen to music @ 75W into 8 Ohms.
Most music falls below 10W into 8Ohms when listened to at home.
So if you have some very difficult speakers then work on this.
10watt into 8Ohm
20watt into 4Ohm
40watt into 2Ohm
80watt inot 1Ohm
You can still have your 75W into 8 Ohm, but since you probably won't be listening at those levels then I think 80W into 1 Ohm is a good compromise.
You are still going to need big heatsinks and a big Toroidal.
I would probably consider an Aleph 0, or an F5 (cascoded input).
According to Wiki I think you are right.
I always thought Pavg = Prms
I don't care about pmpo, in fact if you gave me the formula I would try very hard to forget it.😀
Read this
http://www.hifi-writer.com/he/misc/rmspower.htm
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Hello,
Thanks and advice noted , i will give the other pass Amps a look ...
OK,
So the monster class A is out and while i do agree somewhat with your assessment on listening , 80 watts would be way 2 small , 160 @ 1 would be the min for good dynamics ..
Now ... Aleph J or F5 ?
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That is a tough one.
F5 is simpler to build (less parts, no caps).
The Aleph 0 is a push pull design like the F5 but has some single ended bias, so it acts like a Single ended amp for a few watts before it operates like a traditional push pull circuit.
I have built the F5 but not the Aleph 0, so I can't really say.
Nelson will have to help out here in terms of the listening experience.
F5 is simpler to build (less parts, no caps).
The Aleph 0 is a push pull design like the F5 but has some single ended bias, so it acts like a Single ended amp for a few watts before it operates like a traditional push pull circuit.
I have built the F5 but not the Aleph 0, so I can't really say.
Nelson will have to help out here in terms of the listening experience.