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Old 22nd December 2002, 04:49 PM   #1
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Default Aleph-X: High-Power Version

I have read Aleph-X threats now for 8 hours and I have to admit that I am not yet through with everything. But even with extensive usage of the search functionality I have found some comments how to come to a high-power version of an Aleph-X, but I am not sure if they included all information to be considered. Therefore I would like to collect some of your experiences on that topic as I can imagine that there are some more DIYs out there who have planned to go for an Aleph 2, changed now there mind and want the same thing in terms of power, but with advantages of the Aleph-X.

Here now some thoughts / questions:
- Heatsinking: Also when utilizing now IRFP044 under very different voltages, we are in the same ballpark with the Aleph 2, right ?

- Voltages: Instead of 45 VDC, we are looking now for 15 VDC in the schematics I have seen. Will this hold to be true if raising the IRFP044 from 4 pcs/channel to 12/channel ( The Alephs raised voltages with growing number of fets ?)?

- Components to be trippled: When now coming from 4 044 up to 12: Will really only the fets be trippled or all components around them as well ( what my understanding is right now): In Grey's schematic this would be r7, r5, q1, q2, r6, r9. What about the circuit around the mpsa18 which drive q1 ? Will this drive as many IRFs as I put in parallel or has it as well to be trippled ?

- Are there any other issues to be considered, why in some threats is has been stated that the time is not yet there to go for a high-powered version ?

Regarding Components: What would be your recommendation: IRFP240 (which gives me the option to go back to the Aleph 2 if the Aleph-X is not my pair of shoes) or thhe IRFP044N (which cost me the same, but if have read somwhere the the N-Version is not that suitable for audio; the superior 044 VErsion is diffcult to get though).

Regarding separate PSU for the driver-stage: Do the same comments on the Aleph apply here (meaing not possible as part of the concept) or could this be an improvement ?

THanks & Best Regards
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Old 22nd December 2002, 05:57 PM   #2
Jens is offline Jens  Germany
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Blitz,

- Heatsinking: Also when utilizing now IRFP044 under very different voltages, we are in the same ballpark with the Aleph 2, right ?
> Yes <

- Voltages: Instead of 45 VDC, we are looking now for 15 VDC in the schematics I have seen. Will this hold to be true if raising the IRFP044 from 4 pcs/channel to 12/channel ( The Alephs raised voltages with growing number of fets ?)?
> Ill go for 22 VDC on 12 IRF240 <

- Components to be trippled: When now coming from 4 044 up to 12: Will really only the fets be trippled or all components around them as well ( what my understanding is right now): In Grey's schematic this would be r7, r5, q1, q2, r6, r9. What about the circuit around the mpsa18 which drive q1 ? Will this drive as many IRFs as I put in parallel or has it as well to be trippled ?
> Include r36, r38, r40, r41, q10 and q11. Only q1, q2, q10 and q11 are controlled by the circuits around q3, q4, q8 and q9 (MPSA18). <

- Are there any other issues to be considered, why in some threats is has been stated that the time is not yet there to go for a high-powered version ?
> Uplift the current sources, Ill go for some 7A all-in-all, using 0R39 source resistors <

Jens
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Old 22nd December 2002, 06:58 PM   #3
Cobra2 is offline Cobra2  Norway
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Default Re: High power A-X

A high power Aleph-X, Just what I also had in mind...

Can someone please post schematics on a few versions of this?
Something around 150W+ would suit me perfectly!

Arne K
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Old 22nd December 2002, 07:49 PM   #4
Variac is offline Variac  United States
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Default Lotsa conversions goin on with 700 bds out there!!

Blitz, you beat me to it! I think there are a lot of people out there with Aleph 2's or that they might want to convert or who just want a more powerful Aleph X.

In my case a have 24 IRF 140's, and 2) 37.5 volts toroids.

Cobra:
Because people will be converting from the Aleph 2 could we agree on 100w. ch for the moment? That extra 50 watts would hardly be noticed maybe?

Everyone: Does the standard Aleph X that you have been discussing have a lower voltage just because it is lower powered? or the the X use lower volts for the same output?
Can I use my toroids?

Thanks all
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Old 22nd December 2002, 07:53 PM   #5
grataku is offline grataku  United States
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Cobra,
nobody, that I know of, has drawn up the schematic for this yet, actually I did but that's besides the point. If you plan to be successful in your high power Aleph X you got to be ready to study the aleph, Zen4, and AlephX thread in detail and thuroghly understand what you dealing with and be ready to make mods when mods need to be made. Even though all the info you need are pretty much available, nobody besides Pass labs has built anything close to what you want.
Calculate all voltages and currents, size out all the components. If you have SPECIFIC question on points that you don't understand I think members will be happy to help out.
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Old 22nd December 2002, 07:58 PM   #6
Jens is offline Jens  Germany
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Cobra2:

To get 150W on 8 ohm, you need about 28VDC, 4,35 A current, 12 x Power MOSFETs and source resistors of 0R68 if Im not wrong on this.

Variac:

Compared to the Aleph, the Aleph-X used 1/2 voltage and double bias.

Jens
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Old 22nd December 2002, 08:05 PM   #7
Variac is offline Variac  United States
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Thanks Jens, that's the sort of concise reply that is soooo helpful
For me this is just for long term planning. Now I know to use those toriods in another project- unless I want 200w/ ch !!!!!
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Old 22nd December 2002, 08:15 PM   #8
grataku is offline grataku  United States
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Jens, the current you are proposing is really bare bones for 150W,
you are going to be short if your speakers impedance drop to even 6ohms.
Nelson uses 8amps and +-30V for 200W. I would plan for at least 6 amp bias xchn.
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Old 22nd December 2002, 08:16 PM   #9
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Default Choke-Input ?

Variac,

I have not yet simulated this in PSU-Designer, but I would consider a choke-input-setup, where you have a anyhow a much lower VDC compared to a pi-filter (in theory instead of VDC= VAC*1,414, it would be VDC=VAC*0,9). MArk Levinson has used this in his Cello-Amplifiers as it reduces power-supplier-noise (smoothes the spikes produced by a pi-filter)and gives nice regulation. The trick is to calculate the inductance correct, which is quite small here compared to tube equipment. So, in the case of 28 VDC with 4,350 A it would be 6,5 mH (more is no problem). If you still have to much VDC, have another RC-filter to follow (so you end up with an LCRC-Filter).

Best REgards
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Old 22nd December 2002, 08:34 PM   #10
Jens is offline Jens  Germany
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Mark:

100W on 8 ohm means about 23VDC and 3.55 A bias.
200W on 8 ohm means about 32VDC and 5A bias.

grataku:

I said 8 ohm you are right
150W on 6 ohm means about 28VDC and 5A bias.
150W on 4 ohm means about 28VDC and 6.12A bias.

Jens
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