Yet another Aleph 5.

[PKI]

Greetings!
I am starting my Aleph 5 project, I've read many topics on the forum about it, however, I have some questions and really appreciate if you help me with them.
I attached the diagram of the amp. Ti will be in mono-block form factor.
1) Transformer: Are avel 625VA 25V good choice for the amp?
Avel Y236850 625VA 25V+25V Toroidal Transformer 122-675
or it is better to go with 30V and have a bit bigger rails?
2) PS caps: Is there any difference in how many caps to use?
I mean have two 60k uf caps or four 40k uf caps? Assuming that parameters of each capacitor are equal(not capacitance of cause). So only total capacitance or how you construct it?
3) Outputs: I am going to use pcb from kk-pcb.com, however, they are for a stereo amp, so can I put my output transistors on heatsinks(see pic) and use wires to connect them to pcb?
Thanks!

 

[6L6]

Yes, you can attach Fets to heat sink and wire them to pcb. I am going to have to in my build as well. There are many examples of aleph on the web where you can see it done that way.

Capacitor-- how many can you fit in your chassis? That is how many you want. More capaance is better.

 

[PKI]

Thanks!
But let say I can spend up to $150. So I can buy 4x47kuf now and thats it, or I can now buy 2x60k uf now and some day upgrade for another two of them.

 

[PKI]

Guys, do I need inductors if I'm only using four 60k uf capacitors?

 

[KatieandDad]

Its perfectly OK to mount the MOS-FETs to the heatsinks with remote wires.

My Aleph 4 started with CRC but ended up with CLC.

 

[PKI]

But you have a bigger capacitance of you psu? I am not strong in inductors, what should I look at? AC/MC, current, voltage? Thanks.

 

[AudioSan]

But you have a bigger capacitance of you psu? I am not strong in inductors, what should I look at? AC/MC, current, voltage? Thanks.

you don't need inductors. use 0.5ohm 25W power resistor insted.
a minimum of 4 caps is a must.
if you mount the fets with wires, make sure to move the gate stoppers over to the fets to(221ohm).

 

[PKI]

...gate stoppers over to the fets to(221ohm).

Do not get it, sorry :-(.

 

[a.wayne]

Its perfectly OK to mount the MOS-FETs to the heatsinks with remote wires.

My Aleph 4 started with CRC but ended up with CLC.

Difference , improvements ....... ?

 

[Marra]

Do not get it, sorry :-(.

Solder the gate stopper resistors to the mosfet not on the pcb.

 

[PKI]

Guys, when F5 Turbo is here, maybe it is better to build it instead of Aleph 5. As I understand it could be better for 4-6Ohm 89db speakers. What do you think? I really appreciate any info. I've been reading an searching a lot and there too much info on powering difficult speakers and sound quality (and tonal difference), when people compare F5 with Aleph.

 

[6L6]

That's a white wine vs. red wine question...

An Aleph 5 is a 60W amp. That should be more than enough for an 89db speaker. Unless you like to listen really, really loud. As in ear-ringingly loud.

 

[PKI]

That's a white wine vs. red wine question...

An Aleph 5 is a 60W amp. That should be more than enough for an 89db speaker. Unless you like to listen really, really loud. As in ear-ringingly loud.

Thanks! And which is which?

 

[6L6]

The F5 is the red. The Aleph is the white.

No, wait, I mean the Aleph is the red and the F5 is the white.

Um, well, maybe it's the other way around...

 

[PKI]

Is +/– 30V Ok for a transformer output for Aleph 5, or it is better to go with +/– 25V which is closer to original specs?

 

[PKI]

I am asking because I found on the forum that for 7-8 Ohm speakers it is better to use +/–25V and +/– 30V for 4 Ohm loads. However, I do not understand why? Is it because increasing the rail you increase power->heat dissipation->(to maintain given Temp)-> you have to reduce current(bias?)?

 

[Zen Mod]

maybe it's otherwise ?

lower voltage for lower ohm load ?

 

[PKI]

Oh, yes, other way, my mistake, sorry.

 

[AudioSan]

I am asking because I found on the forum that for 7-8 Ohm speakers it is better to use +/–25V and +/– 30V for 4 Ohm loads. However, I do not understand why? Is it because increasing the rail you increase power->heat dissipation->(to maintain given Temp)-> you have to reduce current(bias?)?

it is because with 25V you get higher amps. thats what you need to drive low impedance loads.

 

[PKI]

Colleagues, final thoughts before heatsink ordering: correct me if I am wrong:
Aleph 5: approx. 150W/Ch -> 20C/150W≈0.13deg/W for one ch. heatsink, right?

I was trying to go with one h-sink per channel, but it is difficult to get one with adequate size. So it will be "stereo" chassis made of four 0.20deg/W h-sinks.