# Keantoken's CFP cap multiplier

#### rensli

##### Member

There is a good reason why i want to try them:

With a CRCRC (R= 1 oHM) TOTAL 2 ohm per rail combination before LM regulators i had more AC trash on the reg´s output than with 470m Ohm resistors(total 920m Ohm per rail).

#### sikahr

##### Member
Put k-mult after 317/337, and add bleeder resistors after k-mult, ask Kean how much mA is optimal for k-mult. Your trafo secondary mA rating is how much ?

#### rensli

##### Member
I leave 470m OHM resistors in place then ?

Xformer is 170mA AC per winding totalling 2x170mA.
2x18V AC, after rectification without load = ~31V DC

I will use ~2k ohm as a bleeder to get current close to 10mA on both rails + opamps will draw ~35mA, it should do the work i guess.
EDIT: Keantoken specifies that these filters wont do any good if current is less then ~25mA.

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#### TNT

##### Member
Paid Member
100mA is best bang for the buck.

//

#### sikahr

##### Member
Add bleeders for desired mA, and then adjust CRC this way: voltage drop on 317/337 3-5 V, rest on CRC.

#### rensli

##### Member
Build the positive side for prototype. Transistors used: BD138G and BC549C and 1000uF 0.06R ESR capacitor instead a 820uF.

On turn on, LED flashes once and than slowly vanishes away.

Seems it works correctly, output impedance is low due to zero voltage variations if load current is changed from 45ma to 140mA.

Voltage drop is 2.05V when the load is given, without load the drop is 1.6V.
Small meter shows current sinking from output "mA"

INPUT ~17V, output ~15V.

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#### keantoken

##### Member
Looks good. Oddly, this is one of the threads that often skips sending me notification emails.

#### PinkPanther-2

##### Member
Can we use Oscons in K-Multiplier, intended to supply a RIAA preamp, or this will colorate the sound? I have several Panasonic SEPC 470uF/16V and I will try to use them.

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#### keantoken

##### Member
Those I know who have tried them with the KM liked the result, and there is no technical reason they would be incompatible.

#### RCruz

##### Member
Paid Member
I do like Oscons, principally on analog amps

#### alexkosha

##### Member
Did anyone try Panasonic FRs in KMs or in general raw DC PSUs? I used then in my 2 analog build and they sound nice, however I did not compare them to anything else in the same builds..

Sent from my iPhone using Tapatalk

#### triode_al

##### Member
I got the excellent Dirty boards. Allow stuffing and resting.

When I stuffed one board, I omitted the R1 47 (or 100 ohms) resistor: still it worked well, but of course not as low a output impedance as with 15 ma extra though the BC337.

The config without a R1 is the same as I have in my LeMonstre power amplifiers...

albert

#### rensli

##### Member
I have build another one(positive), with random 1N4148 diodes, 1000uF 200mR caps, Q1 BC337-40 PH59 and Q2 FairChild BD-140-16.

Everything is stock(default dummy load ~25mA):

across 3 1N4148 i get 1.7V drop
When working with 29.80V input, across R2(1K) i get 38mV drop.
Output - input voltage differential : 2.04V(takes a ~minute to settle down)

Applieng 160mA load to the output increases voltage drop on R2 to 43mV.

Is everything working correctly ? Going to adapt them soon in preamp psu circuits

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#### keantoken

##### Member
Sounds good so far. It passes all the tests except the test that's left, which is how well it blocks input noise. This might be a problem with the BD140.

If you don't mind, please post the following measurements.

1: Get your most sensitive voltmeter (mV accuracy at least) and set it to ACV. Twist the probes together and put the negative probe at the ground pin of C1. Put the positive probe on the negative probe, wait for the measurement to settle and record the value.

2: Put the positive probe at the input of the KM and measure the ACV.

3: Put the positive probe on the output of the KM and measure the ACV.

#### rensli

##### Member
I made some measurements. All info is on the photos.

1. First two pics are comparison between BD140-16 and BD138G builds.
2. Rest of the pics are taken on AC mV range set to manual.

• DC measurements are accurate..
• AC measurements are questionable or not, you decide please.
Forgot to add: AC mV measurements are taken with BD140-16 % BC337-40. There is little or no difference at all @ noise compared to BD138G % BC549C.

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• NO POWER AC.jpg
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#### keantoken

##### Member
The AC voltage with both probes shorted to ground should be nearly the same whether or not the PSU is on. It should be almost nothing. With this inconsistency I can't trust those measurements.

#### rensli

##### Member
Yep, i re-checked PSU on or OFF, tried LM317 based PSU, same results(ACmV increasing when PSU turned on)