questions on aleph 2 parts

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MEGA_amp

MEGA_amp

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I just recently received my aleph 2 PCBs from Kristijan.

Going over his parts list I have a few questions:
The R values for the main board are listed, is there a general wattage rating for the resistors i'm looking for, for the main PCB components? I saw somewhere that all resistors are rated at 25W unless otherwise noted.

per Kristijan's schematic:

1. R1=4,75 K?

is this 4 watts 75,000 ohms? 4.75 K? his notation is confusing me

2. D1-D5= zener 9,1 V

9.1 V? wattage?

3. What voltage is recommended for the caps on the main PCB?
C1=1 nf
C2-C4=220 uf
C5=10 pf
C6=1 nf

4. what will yield the best sound? Bulk Metal Foil, Thin Film, Metal Film. Or is the type non-important?

5. Do any resistors require tolerances of 1%?


Thanks in advance
John
 
E

elizard

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Joined 2003
MEGA-amp said:
Going over his parts list I have a few questions:
The R values for the main board are listed, is there a general wattage rating for the resistors i'm looking for, for the main PCB components? I saw somewhere that all resistors are rated at 25W unless otherwise noted.
Click to expand...

that's 0.25W (1/4Watt) .. 25watt is a slight overkill :)


MEGA-amp said:

per Kristijan's schematic:

1. R1=4,75 K?

is this 4 watts 75,000 ohms? 4.75 K? his notation is confusing me
Click to expand...

That's 4.75Kohms
the ',' in europe is used as a '.' in US/Canada is generally

MEGA-amp said:

2. D1-D5= zener 9,1 V

9.1 V? wattage?
Click to expand...

this is my guess only, but i'm guessing its just a standard zener diode, so whatever wattage they are

The rest of the questions I don't have an answer to, except one last one.
I don't think any resistors REQUIRE a 1% tolerance, however if you can afford 1% resistors i think you'll be graced with a (possibly ever so) slightly better amp.

edit: you can refer to http://www.passlabs.com/pdf/aleph/a2srv0.pdf for more info of course

another edit: the only resitor's wattage you need be concerned about are the 0.47ohm and the 1ohm ones, those i believe are 5watt wirewounds if i'm not mistaken.
 
BobEllis

BobEllis

Member
Joined 2003
Re: Re: questions on aleph 2 parts

elizard said:

the only resitor's wattage you need be concerned about are the 0.47ohm and the 1ohm ones, those i believe are 5watt wirewounds if i'm not mistaken.
Click to expand...

THE RESISTOR POLICE ARE COMING TO GET YOU, ELIZARD! BAR THE DOORS! :D

Some say that you should use thick film resistors here, but I plan to use cement wirewounds. Maybe when I have silly money I'll try something exotic, but for now I'll worry about choosing the best sounding transistors.

As for capacitor voltage ratings, I'd go slightly above the rail to rail voltage for the 220uf (eg. 25 volt rails, rating > 50 V) for teh others the dc potential across them is small, so virtually anything will do.
 
moe29

moe29

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Joined 2002
the lowest values you'll be able to find for the small caps will be
well within tolerences (1nf, 10pf) The 220uf cap = 50v (Digikey part# P5572-ND)

Zeners = 1watt (Digikey part# 1N4739ACT-ND)
NTC (for power supply inrush limiting) KC006L-ND
10PF cap 399-1806-1-ND
.001uF P4785-ND

(i'm sure there are better sounding parts that could be substitued
for the above, but you can get all these at one place, and they work!)

m.
 
moe29

moe29

Member
Joined 2002
...i think i need a LearJet.

the only Black Gate cap i see on Percy Audio that fits would be a
220uF 160V NH for 29.95 USD a piece. Times 6 for stereo Aleph 2
would be $180.00 ..... YIKES!!! :bigeyes:

or are you just talking their Standard Polarized line, which would
be 220uF 50V for $6.95 USD for $42.00 total.

You can get 10 of the Panasonics i posted for $4.10 USD.

I'd try them first and see how things sound.

Pass Labs uses the same Panasonic resistors in their Amps, they
can't be that bad.

the above caps and resistros sound great in my Aleph 2's.

...go figure.
 
jewilson

jewilson

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Joined 2002
Seeing how that this cap on the inverting balanced input, I would not use just any old cap there Moe. However, the 220uf for the bias could be a Panasonic, it’s not that important since it not in the signal path. If the PCB had room I would use and Black Gate and parallel with a Polypropylene 2uf on the input only.

I just hate to use parts that know I will remove later, just cost more time and money.
 
moe29

moe29

Member
Joined 2002
Jim,

C5 is the cap you are saying should be Black Gate right?

what you're saying makes since - and i'm not saying that Black Gates
don't make any difference sound wise... Just hard to reccomend
them for a first time build. (i'm assuming this, becuase of the
questions from the original post)

I guess i'm just always for getting the circuit built first, and then
doing upgrades later.
 
Magura

Magura

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Joined 2003
class-a-labs.com
True, but in the end i understand the question being that he dosnt want to spend un-nessecery money, not that he dont want the best possible....maybe im wrong.

In the end of the day its terribly expensive to upgrade half of the amp by buying better parts (that could have been bought in the first place) within the first 2 weeks.


Magura
 
T

tomchaoda

Member
Joined 2003
Where can find these parts?

I can not find the thermostatic switch rated at 75 degrees C used in Aleph 2 and 5 in either Digi-key or Mouser! Does anyone has the part number to order?

Also, I like to use the copper plate to connect the large filter cap. Local Home Improvement store does not have it. Anyone knows where I can find them (in US)? (like a 2mm thickness used in the photo)

Thanks

Thomas
 

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moe29

moe29

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Joined 2002
The point i'm trying to make is you do not need to build
an Aleph 2 with exotic and expensive parts for it to sound good.

The Aleph series was Class A pretty much across the board - no
matter who was reviewing.

My Aleph 2 sounds great and compares nicely to my production Aleph 3...
sans exotic parts.

First time builders shouldn't be lead to believe that their amp
will be second rate if they don't use exotic parts. And where's the
fun of experimenting if you use exotics right off the bat? You have
nothing to compare to. Someone certainly isn't going to take out
Black Gates to see if it sounds better with Panasonics! ;)

(sorry if i'm going on and on)
 
T

tomchaoda

Member
Joined 2003
Parts found!

:knight:

Thanks for all info regarding parts question I posted earlier. I also find them and would like to share with you.

For the 75C Thermostatic switch, I find one I like in Digi-Key.

Digi-Key: #317-1001-ND

Mouser has Vishay Thermal switch rated at 70C or 80C, but not 75C. However, they do not have them in stock!

For the copper flat sheet:
for 1 mm (~0.04"), they have it in Thompson Emanel, link here:
http://www.thompsonenamel.com/products/metals/copperflatsheet.htm

For 2 mm (~0.09"), I found it on eBay, but it is not cheap! But I like 2 mm for better conductance.

FYI

Thomas
 
Magura

Magura

Member
Joined 2003
class-a-labs.com
Re: Parts found!

tomchaoda said:
:

For the copper flat sheet:
for 1 mm (~0.04"), they have it in Thompson Emanel, link here:
http://www.thompsonenamel.com/products/metals/copperflatsheet.htm

For 2 mm (~0.09"), I found it on eBay, but it is not cheap! But I like 2 mm for better conductance.

FYI

Thomas
Click to expand...


You should rather use 2 * 1mm than 2mm for better conductance....wich is though irrellevant in this case, since 1mm * 25mm copper bar is more than overkill already :D

Magura
 
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