Keantoken's CFP cap multiplier

If I may... There are plenty of 2SA1930 in Mouser or DigiKey. And 2SA5171 I acquired from eBay guy. Please see attached picture.
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I used already 3 of them and seems they are original Toshiba made transistors. No issues what so ever...
I'll send you guys a link to that eBay source.


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keantoken, i finally had time to test your circuit in real action.

Yesterday, i was modifying the Texas tidu34 volume control. Got it sounding just right with LM317AT+LM337AT. Using Thailand NE5532 and OPA2134 from texas.

Tidu34 controls the volume for naim NAP140 clone amplifier.

The i had an idea to try you K-multiplier:
1. Took a transformer 14VA
2. Built PSU filter with LOW ESR 470uF electrolytes.(CRCRC, R= 330mR)
3. At the last electrolyte from Filter-Bank, installed there k-multiplier.

Output before k-mult = 16V +/- VDC
Output from k.mult = 14V +-/ VDC

While soldering stuff together i was listening to LM regulator PSU.

Cut the power off Tidu34, replaced LM regulator psu with filterbank + k-mult.

Turn on and WoW, everything is sooo different... soundstage/dynamics/acoustic are completely new story lol.... how is it possible :D

First i tought, its the filter in AC 230V line, today i removed the AC filter, sound is still same :)

I miss that relay switch to compare between different amps and speakers(and also switch between PSus)... i will get on it and then will tell the difference lol :D
 
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Some fotos:

Filter capacitors are all the same brands in LM and k-mult filter-bank.
All samwha-s, dirty cheap. Capacitance amount is also the same 2200uf + 2x 470uF.

Sound still so different :D
 

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Hi all!

I'm new here, and I have a problem with K-multi (positive version).
I've built the K-multi width BD140-16 and 1 piece of 1N4148 diode.
And I've put in the LED in opposite direction (but theoretically it should not make any difference).

In addition I use a 10nF X7R between the B-E leg of the BC337, and I use one 100nF X7R parallel to each elektrolite capacitor.

The input is voltage came from a stabilizator circuit width LM1084.
This is it's output characteristic measured by Scope.
The output is 12v 1,2A (load resistance was 10 ohm 20W).
After I connected the K-multi to the stabilizator circuit I got the following result measured by Scope.

Can anybody tell me why is it have 25MHz sinus noise on it.
 
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It seems up to now, the K-multiplier presupposes a power supply with C-filter to smooth the DC input voltage (so an elco of significant capacitance after the bridge rectifier). In terms of function a K-multiplier might be seen as a substitute for a choke. So, the K-multiplier as an electronic choke. Would it be allowed to use a K-multiplier as a choke-input filter? That is, a K-multiplier right after the diode bridge, and the smoothing C after the K-multiplier?
I only ask whether it is technically allowed, not if it would be the optimal place.
 
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Joined 2003
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Yes, I am aware that a large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. I notice that in the choke input filters for my tube amps. But its peak would diminish fast as soon as current is drawn. Is it an option to simply add a zener of appropriate voltage between the rectifier and the K-multiplier to tame the peak?
 
Hi all!

I'm new here, and I have a problem with K-multi (positive version).
I've built the K-multi width BD140-16 and 1 piece of 1N4148 diode.
And I've put in the LED in opposite direction (but theoretically it should not make any difference).

In addition I use a 10nF X7R between the B-E leg of the BC337, and I use one 100nF X7R parallel to each elektrolite capacitor.

The input is voltage came from a stabilizator circuit width LM1084.
This is it's output characteristic measured by Scope.
The output is 12v 1,2A (load resistance was 10 ohm 20W).
After I connected the K-multi to the stabilizator circuit I got the following result measured by Scope.

Can anybody tell me why is it have 25MHz sinus noise on it.

Sorry I missed this. Can you tell me why you made those changes? If anything the 10nF cap should go on the B-E of the BD140. And I think I have seen more than one KM using the BD140 that oscillated.

The KM should have capacitors close to both the input and output, but 100nF film caps are unnecessary and sometimes will even cause oscillation.
 
Yes, I am aware that a large inductor right after the rectifiers can see extreme ripple and negative voltage at the input. I notice that in the choke input filters for my tube amps. But its peak would diminish fast as soon as current is drawn. Is it an option to simply add a zener of appropriate voltage between the rectifier and the K-multiplier to tame the peak?

The KM would have to turn on and off to charge the reservoirs, and a zener does not store power and so cannot support the input voltage of the KM when input is low. A zener to reduce the positive peaks would either short the rectifier or it would go across the KM, effectively bypassing it and ruining the goal of filtering.
 
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Joined 2003
Paid Member
Another question to explore the versatility of the K-multiplier, when allowed.
The current capability of the K-multiplier is limited to about 1A. Earlier you mentioned it is hard to design for more current.
Would it be feasable to increase the current capability by putting two K-multipliers in parallel?