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-   -   Aleph 30 completed and listened (http://www.diyaudio.com/forums/pass-labs/126210-aleph-30-completed-listened.html)

N-Well 11th July 2008 12:37 PM

Aleph 30 completed and listened
 
Hi,

Some pics of my last bass amplifier (and my whole system by the way).
Very nice sound , tube like but with punchy bass as well, . To so far a very good compromise. I used to have before a DIY class T amp in the bass, was very punchy but voices were not nice at all
, i got tired of it..

http://picasaweb.google.com/Platesur...ey=m_4hban5g8k

I questionned myself now on the fact I put some wirewound resistances (6 X 0.47ohm in parallel) in the set in serie with the load , at the output of the amp. could it be a problem due to inductive part of these components ?


have a nice day.
nwell

Zen Mod 11th July 2008 01:22 PM

Re: Aleph 30 completed and listened
 
Quote:

Originally posted by N-Well
.....

I questionned myself now on the fact I put some wirewound resistances (6 X 0.47ohm in parallel) in the set in serie with the load , at the output of the amp. could it be a problem due to inductive part of these components ?

......


nope - that inductivity is negligible ........... at least enough negligible ;)

zeonrider 11th July 2008 01:34 PM

Hi!
 
2 Attachment(s)
Nice work, spagheti I, like it!!

Look yelow skribe.

Regards zeoN_Rider

AndrewT 11th July 2008 01:49 PM

the pic says the item on the left is the soft start. Looks to me like a Halogen Bulb used as the resistor.

N-Well 11th July 2008 02:12 PM

Yes the Holgen is used as a resistor !

CL60 would have been simpler ... we have a say over here... why doing things simpler when one can do it complex !
what is nice about it is the big Flash at start up...

nwell

AndrewT 11th July 2008 02:48 PM

but the tungsten filament has a positive temperature coefficient instead of the Thermistors negative temp coef.

N-Well 11th July 2008 03:33 PM

The inrush current limiter works this way:
When the tube lights up, its resistance increases a lot rapidly, once le bigs caps are charged ( 700 000 F total at 24V), a relay shorts the tube (about 2 to 3 secs after power on).

nwell

AndrewT 11th July 2008 03:59 PM

Quote:

Originally posted by N-Well
The inrush current limiter works this way:
When the tube lights up, its resistance increases a lot rapidly, once le bigs caps are charged ( 700 000 F total at 24V), a relay shorts the tube (about 2 to 3 secs after power on).

nwell

it's back to front.
High resistance at start up to max attenuation of starting peak (surge).
Falling to a lower resistance as the caps charge up and eventually allowing full voltage on both the primary and secondary sides of the transformer.
This requires a neg temp coef.

Mooly 11th July 2008 05:15 PM

Listen to the man !!! It is back to front -- yes. Two soft start circuits in one day Andrew !
"When the tube lights up it's resistance increases a lot rapidly"
Why do you think that is ? Tell you what, and I have tried this, put a 240volt 500 watt halogen across a 12 volt battery and it glows the resistance is so low.
Nice amp though ;)

Forgot to say, the main problem is that your compromising your amps max output. The more power delivered to the load, the hotter the filament gets, so the supplies drop.
Then again this could be the latest in protection circuits and AGC
:)

N-Well 11th July 2008 09:12 PM

The halogen tube is shorted by a relay 2 or 3 s after power on,
meaning the amp is supplied with AC on directly, no issue
with Amp load or what so ever.

Yeah, I know, not ideal. The truth is ... I did not have the patient
to ... order CL60 to digikey US. could not find anywhere else
to buy those from France at decent price... and since I had this soft start device to recyle...


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