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Old 30th March 2004, 07:45 PM   #11
Stocker is offline Stocker  United States
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Default Is this a stupid question?

Instead of a 150lb. amplifier with multi-henry chokes-

-could a gyrator be used instead?

circuit complexity goes up but that has to be weighed ( ! ) against the cost and mass of all that copper.
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Old 30th March 2004, 11:26 PM   #12
Nelson Pass is offline Nelson Pass  United States
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Default Re: Is this a stupid question?

Quote:
Originally posted by Stocker
Instead of a 150lb. amplifier with multi-henry chokes-

-could a gyrator be used instead?

circuit complexity goes up but that has to be weighed ( ! ) against the cost and mass of all that copper.
If you're going to increase the complexity, the next step up would
likely be an Aleph current source, which tracks against current,
essentially "ghosting" the load. That system would run at twice
the voltage and 1/2 the current, giving roughly the same efficiency
as a coil.
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Old 31st March 2004, 09:48 AM   #13
hacknet is offline hacknet  Singapore
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sounds like something i would like....

i`d try implimenting these current sources, lets see how far i get
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Old 31st March 2004, 09:58 AM   #14
hacknet is offline hacknet  Singapore
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i did look at the aleph current sources. it looks very much like those on the zen v2. is this correct?

if it is, i`m actually running into a problem. i don`t have enough heatsinking and enough budget to get another pair to do the job....

i did a rough calculation and found my zen lite`s mosfets to be dissipating roughly 25w since the source voltage is 12v and the current drawn is 2.1 ampere. the heatsinks get very hot. too hot to touch. i don`t know if these are because of the bulbs dissipating 240w in that small area or is it because of the fets.

my heatsinks are 9'' by 5" by 1.5" fins. can anyone help me determine if my heatsinks are big enough for a current souce?

i am using a 50v trans at the moment i have another 24v 12ampere trans waiting to be used. could the calculations be done for a 35v supply? thankyou for the help!
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Old 8th April 2004, 04:41 PM   #15
Tyimo is offline Tyimo  Hungary
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Default need some answers

Hi!
I try to ask one more time: would the attached circuit work as it is?
-and if : would a 2X16V -400VA transformer enough for two channel?
-what is the max voltage for this amp?
-what typ of the zener?
-is it possible to use IRFP240 instead of the BUZ900 without any change?
-needn't I adjust somhow the circuit? There isn't any trimmer..
Thanks!
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Old 8th April 2004, 04:59 PM   #16
Fuling is offline Fuling  Sweden
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It *should* work as it is, but I think the power supply has to be regulated to avoid drifting bias.

16VAC gives ~22,5VDC after rectification (minus diode losses), which is a bit low if youre going to regulate it.
I guess the circuit will work just as fine at slightly lower rail voltage, though.

Id use a 12V zener.

IRFP240 should work fine AFAIK.

Id replace that 4k resistor with a 4,7k trimmer in series with a 2,2k resistor.
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Old 8th April 2004, 05:18 PM   #17
Tyimo is offline Tyimo  Hungary
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Thanks Fuling!!!
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Old 8th April 2004, 05:45 PM   #18
Fuling is offline Fuling  Sweden
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Youre welcome.

Ive spent a lot of time philosofing about similar circuits, and what did I come up with?
Getting high input impedance, low output impedance, stable bias,
low parts count and so on at the same time is not easy. Maybe not even possible.
Sacrifices has to be made somewhere, and its up to each designer to decide what to sacrifice.

The major drawback (according to me) in this schematic is the low input impedance. It cannot be "fed" from a CDP though a passive attuenator.

Ive chosen another path towards nirvana, which is choke loaded Mosfet followers.
A 30 W balanced version is soon to be ready and Im making plans for a bigger project in the future.
Not quite as elegant but way easier to mess around with.
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Old 19th January 2017, 02:23 PM   #19
oks81 is offline oks81  Norway
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Old thread, but I had to give choke load a shot
Look at drawing.

Bias is about 1,4A and stable.

Sounds nice, but I do only use it from 600Hz and up on JBL horns.

Tried it on some small bookshelf speakers.
It played bass fine on the small speakers, but with the small 28mH chokes thinking it won't play lower than 45Hz or so...?

Also have som low frequency hum, but no problem on the horns.


Gain is also a bit low.

On the positive side it does not dissipate so much heat

Any tweaks to make it better is welcome!
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Old 19th January 2017, 03:00 PM   #20
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