Aleph 30: project completed

[AndreaFx]

Six months ago I decided to make this amplifier

Given my limited technical bases (i'm not in the field of electronics) and my character "precise" I bought the PCB ready on www.chipamp.com
The same site provides the entire shopping list to be done where there is more comfortable.

I'm worked mainly in the evening and some weekend stealing an hour here and the hour of my little free time.
The total expenditure was around 500 € but wishing you can safely spend half if not less.

Here are some photos stepper
(WARNING! To view, copy and paste the link in a new Explorer's page)

- Power Supply
http://andreafx.altervista.org/Temp/10042008141.jpg
http://andreafx.altervista.org/Temp/10042008143.jpg

- Amps Boards
http://andreafx.altervista.org/Temp/27042008145.jpg
http://andreafx.altervista.org/Temp/27042008146.jpg

The back-and heatsink
http://andreafx.altervista.org/Temp/15062008164.jpg
http://andreafx.altervista.org/Temp/15062008165.jpg

- Assembly cabinet
http://andreafx.altervista.org/Temp/26062008166.jpg
http://andreafx.altervista.org/Temp/26062008167.jpg

Amplifiers completed
http://andreafx.altervista.org/Temp/29062008168.jpg
http://andreafx.altervista.org/Temp/29062008169.jpg
http://andreafx.altervista.org/Temp/29062008170.jpg

The general start for me was a really exciting time and hear the first notes out of the 2 small AP, repaid all the sweat poured.

This is the fourth amplifier that i realize, the first of a certain thickness, shortly starting with the brother Aleph P. ..... Stay Tuned


I attached the amplifier directly to the CD (which has the volume control) taken by the RCA.

I noticed a strong background noise if I link negative signal to earth (with the switch). The background noise disappears when I delete the link to the detriment of gain.
I's normal?

Sorry for my bad English

Andrea

 

[Magura]

Pics not working


Magura

 

[AndreaFx]

Pics not working


Magura

(WARNING! To view, copy and paste the link in a new Explorer's page)

You do it?

 

[AndrewT]

Hi,
what is that band around the top of the toroid?

Is it a shorted turn?

 

[AndreaFx]

Hi,
what is that band around the top of the toroid?

Is it a shorted turn?

Sorry but i don't understand the terms "shorted turn"

I use the bracket (aluminium) around the trafo to stabilize them in vertical position. There's not enought space to place orizontally.
Under the bracket and trafo i put a neoprene sheet do reduce the mechanical hummm.

I know that is not the best position because the bracket warm a lot during normal use of the amply

There are other problems with the bracket?

 

[AndrewT]

Hi,
the clue is that the bracket got warm.

Remove it before you switch on again.

The bolt and the aluminium act like a single turn around the toroid and pulls enormous current making the bracket warm, but much worse it causes severe overheating of the primary and risks damaging the toroid beyond repair.

There must be numerous warnings about shorted turns in the Pass Labs section!!!

 

[Alain Dupont]

AndreaFx,

The aluminium braket could lead to a shortcut!
If the bolt and braket on the top of the toroid are connected without insolation washers...

Nice job!

Regards.

Alain.

 

[AndreaFx]

Thanks guys for the information

The "shorted turn" can caused problem at the sound quality or only at the trasformer?

I use the rubber under the insolation washers on both sides of the trasformer.
I can use another rubber upon the washers?

would prefer not to cut the bracket........if possible!

 

[Alain Dupont]

AndreaFx,


I understand your concern for handling the toroid weight.

If this is not creating a shortcut ; otherwise it could load the toroid real badly...

A shortcut of one turn of heavy aluminium and bolt would lead to

dozens of amps and could destroy the toroid...

Neoprene washers are fine, but they must wistand heat ; use the same
Neoprene as the big insolation washer sold with the toroid.


Regards.

 

[AndreaFx]

Ok Alain i try to do as you are suggesting, thank you

 

[AndreaFx]

If I link the trafo in this way? It's Okay?

The shorted turn it's deleted?

I found another small (I hope) problem and i need help.
When i power on the ampli with the source detached, all it's ok, but when i attack the RCA cable (source is off) a noise (like Zzzzzzzz) coming out from the speaker.
which may be the problem? A ground loop?

 

[Alain Dupont]

AndreaFx,

Yes that's much better ; the shortcut while mounting the toroids verticaly is common,
but not often explained on manufacturers sites...

Probably ground loop,
Check if all your masses go to the same point, and if it's separated from the chassis.
Check if cables cross the power supply 60 Hz primary cable at right angle.
Are your Input RCA jacks insolated from the chassis...
Try rotating the toroid, and see if there is a position where the buzzz is lower

Take care, and good luck with your projects.

Alain.

 

[AndreaFx]

Thanks Alain

-All the masses go to the same point, of course! But i read ever that the masses be united with case........it's an error?

-The primary cable is separated by all cables

-The input RCA are insolated from chassis

-I will try some test with toroid this week-end

 

[Alain Dupont]

AndreaFx,

Masses !!! The best way to get humm ...

You have to read some nice explanations about ground-loops:
http://www.passdiy.com/pdf/articles/ground-loops.pdf

And take a look at this one, just the first schematic...
Chassis, Earth, Ground...
http://www.passdiy.com/pdf/a75p2.pdf

Regards.

Alain.

 

[AndreaFx]

I've eliminated the shorted turn with the cut of the bracket. Now the temperature it's ok!!

For the noise, i do some tests.......the problem disappear only when disconnecting the earth from power cable

There're another method to resolve the problem now that I know the reason?

 

[AndrewT]

For the noise, i do some tests.......the problem disappear only when disconnecting the earth from power cable

What if the power amp alone is connected to the speakers and the input has a shorting plug fitted?

 

[AndreaFx]

What if the power amp alone is connected to the speakers and the input has a shorting plug fitted?

What is a shorting plug? How can I build?

 

[AndrewT]

shorting input plug = RCA plug with a shorting wire link between the pole and the barrel.

Alternatively you can make up a set of input plugs. zero ohms, 50r, 100r, 200r, 1k0, 10k. A pair of each value labeled and put on the shelf for future testing.

 

[AndreaFx]

shorting input plug = RCA plug with a shorting wire link between the pole and the barrel.

Alternatively you can make up a set of input plugs. zero ohms, 50r, 100r, 200r, 1k0, 10k. A pair of each value labeled and put on the shelf for future testing.

Oooook all clear, tanks........i can try to connect positive and negative input with a wire for a test.

After i report here the result, ok?

 

[AndreaFx]

This is the layout of my mass........it can help for the problem solution?