Double CLC power supply for Aleph 1.2,s

[daly2k]

Has anyone built the Aleph 1.2"s? I built a pair back in 2001 and they have worked fine ever since. I am planning to bi-amp a set of line arrays that I have finished. With the Aleph's I still get a very small amount of 120hz hum in the speakers with my ear plastered right up on them. They are line arrays and I am estimating they are 90+db efficient. They are dead quiet from the listening chair.

I was thinking of adding a second set of Inductors to the power supply. I have 8-75watt-7500uf caps per side. I put the first set of Inductors (air coils) after the first 4 caps. I can't remember what the Inductor ratings are but I think they are 1 or 2 mh.
Can anyone help me here or do I need to find my old textbook and do the math again? I would put them after the first two caps.

I have a 2kva transformer and the politically correct hexfred diodes with snubbers in each mono amp.

Has any body done this? Would it work to further reduce the residual hum? The reason for this is that I want to use the Alephs to drive 12 ribbon tweeters per side (Fountex 5" ribbons) that will be digitally crossed over at 2500hz at 96db. As you can guess the tweeters may not like 120hz as they spec out at 1500hz. I am planning to put a 40uf cap in series with the Aleph outputs as a protection from dc offset and any turn on thumps that might occur due to a bad switch or something; since replacing 24 tweeters at $100 bucks is not good.

I am going to use my A-75 for the mid bass drivers.

Man it is hot here today. thanks, dave

[Zen Mod]

www.duncanamps.com

download more then useful proggie called PSUD (for designing PSU) and play with ...... you'll learn and see what you want

[daly2k]

Mr. Zen Mod thanks for the tip, I will look into your site. dave

[apassgear]

I have used 15mH similar as yours on an Aleph 4 with good results but the best is to have them at the input which I now use and is a complete different animal, dead quiet and free of diode grunge.

The drawback over an LC is you will have to deal with a drop on rail voltage.

[wuffwaff]

Hi,

8x 7500uF doesn´t seem to be very much for an Aleph 1.2. Is this per rail or total per amp?
I would try a bit more caps, especially after the inductors.

William

[jasonlky]

From reading the Pass literature, the production version of the 1.2 uses 4 x 25,000uf caps per mono. So I'd agree with wuffwuff that you should first try to beef up your capacitance, at least double what you already have. And the bypass these electrolytic caps with a poly cap or two.

[Zen Mod]

Originally posted by apassgear
I have used 15mH similar as yours on an Aleph 4 with good results

EI cores?
if yes,give us some data-can be handy for future....

[apassgear]

Yes, home brewed, gapped EI 100's M15 coiled with 14 Ga., 15mH, 4 Amps

Also did similar one's (about 8 of them) for another forum member plus 5mH's on same core with 12 Ga good for some 8 Amps for Aleph's 1.2

Regulation on rails seemed like active on the scope, I was surprised to say the least. Not to mention the effect soundwise.

Ended using the coils on an LC configuration and almost sure I could reduce capacitance to 1/2 with no ill efect.

[Zen Mod]

Originally posted by apassgear
Yes, home brewed, gapped EI 100's M15 coiled with 14 Ga., 15mH, 4 Amps

Also did similar one's (about 8 of them) for another forum member plus 5mH's on same core with 12 Ga good for some 8 Amps for Aleph's 1.2

Regulation on rails seemed like active on the scope, I was surprised to say the least. Not to mention the effect soundwise.

Ended using the coils on an LC configuration and almost sure I could reduce capacitance to 1/2 with no ill efect.

hehe
welcome to the tube world...where filament chokes were common

my Babelfish (still waiting for my "free" time) will have 800VA donut with 50K-9mH-5oK in CLC ;
I have pair of those 9mH chokes from ancient PS-es for cinema projectors-they were used for smoothing current feeding sound bulb (6V,5A) .
EI72 core,height of stack is 30mm ,gap ~ 0,5mm,filled with 1,2mm dia wire (~16 Gauge?)


according to my conversion-your 14 gauge is around 1,6mm dia?

ya know that I'm in Europe (at least geographically) so I'll be thankful if you write for me exact height of lam stack for EI100,just because I really dunno where my tables are and I'm pretty sure that I realized somewhere in the past that there are at least few standards for package heights........

can you write down also AC voltage ,current and LC values,and also DC output value-can be handy as hard fact

TIA

btw-how's your origigi NS10 project?

[apassgear]

Here ya go Tooboy, from my RDH tables,

16 Ga = 1.29 mm
14 Ga = 1.63 mm
12 Ga = 2.05 mm

Used Standard stack from this side of the world which is about 22mm.
Standard stacks, as you imply, are more a manufacturer standard, since I wanted to use the sh**** metal bracket I used what I could source locally.

Now, from memory, used around 0.5 mm physical gap which translates to 1mm effective on a EI core, I did played safe, didn’t care using a bit more copper, calculations gave about ½ of that gap as I remember.

I’m not quite sure to understand your other questions but let me try some answers:

DCR is almost non measurable with my bridge. I did take measures but don’t have at hand the notebook, they read something like 0.008 ohms.

For the Aleph 4 I use only one +/- PSU for both channels. Rails are around 48V.

The LC for that setup is 15mH plus 160mf on each leg with small MKP’s bypass. The trafos are a couple of 750 VA EI 150’s with a stack of 90 mm, home brewed of course. Secondarys were coiled with 12 Ga, a tight fit to say the least.

Changing gears now, I did received from our friend Steen a full set of PCB’s for the NS10 plus a lot of other beautiful toys he managed to stuff on a big box. F2 completely stuffed, ZV9 Veteran’s plus the one we design for a more audiophile components like BG and MKP’s. Waiting to put my hands on those as soon as I get rid of some work.