Top ten ways to a better Aleph?

[apassgear]

Lesson learned.

Thanks AudioFreak I knew I was missing something, you are right all the way!!!

[apassgear]

Forgot to say that in addition to the inductors I also made the following additios to the Aleph 4.

Bypassed the CCS zener to the dif pair with a 0.1u and also added a 0.47u to each rail, all of these caps are Wima MKP 10.

All in all very worhtwhile mods.

Did some extensive listening yesterday night. As soon as the break-in was almost over (about 3 hours) everything came in very nicely. No problem with bass slam as I mentioned before.

Not to say that the sound is dry but it seems to me that some decay information is missing, think that this has to do with the low voltage I now have on the rails (32V down from 44V).

[apassgear]

Now having the LCRC PSU I plan to add jet another section to it not because I need it but to get the rail voltage up again, And also because I want the inductors in that position to protect the caps which are only rated to 50 V (63V surge).

So the next step is to add some caps on the front to end with a CLCRC type of filter (kind of overdone???).

One question, is there a way to calculate the amount of capacitance needed at the front to get a desiered voltage?

Happy listening!!!

[Coulomb]

Originally posted by apassgear
Now having the LCRC PSU I plan to add jet another section to it not because I need it but to get the rail voltage up again, And also because I want the inductors in that position to protect the caps which are only rated to 50 V (63V surge).

So the next step is to add some caps on the front to end with a CLCRC type of filter (kind of overdone???).

One question, is there a way to calculate the amount of capacitance needed at the front to get a desiered voltage?

Happy listening!!!

Your rail voltage is really a mathematical relation to your input voltage and the Recifier stage. Although adding an inductor pulls down the rail voltage, there is no way to boost it after rectification without affecting current flow.

Capacitors only store energy to release it on the next cycle, which gives you a clean DC rail and adds some energy (stored) to the circuit.

You can try using HEXFREDs instead of a bridge as they are more effcient, change your Transformer or insert a variac wired 0-140 VAC to boost your input voltage. As the transformer will work just as well with a slightly higher input about 5% you will get o higher output from it. This higher output means more energy for the Bridge to rectify. There is on caveat, that is less available current from the variac once you go above line votage to step up mode.

You will also need to make sure you get a 10 to 15 Amp variac for the job. It will need to stay in circuit all the time.

Anthony

[dshortt9]

There is a great free program for designing power supplies here:
http://www.duncanamps.com/psud2/index.html

[AudioFreak]

Originally posted by apassgear
Now having the LCRC PSU I plan to add jet another section to it not because I need it but to get the rail voltage up again, And also because I want the inductors in that position to protect the caps which are only rated to 50 V (63V surge).

So the next step is to add some caps on the front to end with a CLCRC type of filter (kind of overdone???).

One question, is there a way to calculate the amount of capacitance needed at the front to get a desiered voltage?

Happy listening!!!

If you keep the capacitance directly after the bridge the same as it was initially, you'll end up with pretty close to the original output voltage less the loss from the DCR of the inductor.

[apassgear]

Originally posted by AudioFreak


If you keep the capacitance directly after the bridge the same as it was initially, you'll end up with pretty close to the original output voltage less the loss from the DCR of the inductor.

Well, thanks again, that is what I thought.

[ThomasLMcLean]

There is a very good discussion of the elements of solid state power supply design in the Radio Amateurs' Handbook. You should be able to find a copy of it in nearly any library. It is published every year. A good chapter on solid state power supplies has been included in every issue for the last 20 years. I have recently checked out the issue from 1981 and found that it included a good explaination of the effect both capacitence and choke input configuration has on all of the other components, output voltage, and noise. It also includes all of the design formulias need to do a class A design engineering job.

The text is written for the amateur electronics DIY'r.

PS; I don't think the lower voltage is causing you a problem. I suspect that the output is simply much cleaner then your are used to hearing and, therefore sounds thiner then it did before.

In any case, good luck with your project.

Tom

[apassgear]

Originally posted by ThomasLMcLean
There is a very good discussion of the elements of solid state power supply design in the Radio Amateurs' Handbook. You should be able to find a copy of it in nearly any library. It is published every year. A good chapter on solid state power supplies has been included in every issue for the last 20 years. I have recently checked out the issue from 1981 and found that it included a good explaination of the effect both capacitence and choke input configuration has on all of the other components, output voltage, and noise. It also includes all of the design formulias need to do a class A design engineering job.

The text is written for the amateur electronics DIY'r.

PS; I don't think the lower voltage is causing you a problem. I suspect that the output is simply much cleaner then your are used to hearing and, therefore sounds thiner then it did before.

In any case, good luck with your project.
Tom

Tom,

Thanks for the input, I have a 1957 edition of the Radio Handbook (Spanish edition) which I just saw having a lot of information an the subject. This book has been neglected always since I also have the RDH last edition but havent looked either on the subject since I need some time to take a dip.

I guess your comment is right-on on having a much cleaner sounding amp, I have thought of this as having reduced considerably the IMD.

After the addition of the inductors it was as having a different and much better amplifier.

After this experiance, in my view PSU's for SS (and for that matter also vacumm) is a much neglected issue. Of what I'm sure is that I'll never do again a PSU without the use of inductors for which now I have several at hand.

[Lucas_G]

Originally posted by Mark A. Gulbrandsen
Use twice as much heatsinking as you calculate you will need, and then leave out R-19 from the circuit all together. This should give you the best sounding Aleph you've ever heard!! This will bias the amp all the way up...at least as high as Q-5 will allow.
Mark

Originally posted by Mark A. Gulbrandsen
Hi Klaus,

When I say R-19 I mean in the Aleph 2 and Aleph 5. Its a different R number in the 3 but the equivelent resistor in the 3 does the same thing. I think its alot higher value to begin with though. For the 2 or 5 I reccommend a 250K pot be inserted in place of R-19, and then you listen at different bias levels gradually working the bias up till you get the maximum drop across the source resistors. In my 2's thats just under .7 volts across the source resistors.
Regards,
Mark

Hi Mark,

I am still a bit confused here:
I have done the modification that WuffWaff did with his Aleph 5;
He wrote: "Since the last reports I changed the trimmers for R19 and R21 with resistors (49k and 390R) so now it runs at 2.4A bias and about 63% ac current gain (about 6.7A peak)."
Here is the thread: http://www.diyaudio.com/forums/showt...7253#post77253

So all in all he changed R19 from 221 K in the original scheme down to 49 K while also changing R21 to 390R.

This should have made for a higher Bias, or am I wrong?

Now Mark suggests leaving R19 totally out, which makes R19 getting to an infinitely higher resistance, which should make the bias lower....????????

How can this be explained?
Hopefully Mark and WuffWaff can help me out on this....


Mark, to what total bias does you Aleph 5 go when leaving out R19 altogether? How much dissipation does this bring per channel / per mosfet? Can you describe the change in sound?

All help appreciated...

Regards,

Lucas