August 2008

Executive brief:

What is Fetishizator?

Why do I write about the kindergarden electronics ?

How does lampizator compare to fetishizator?

I/U (wrongly called I/V) conversion of TDA1541A DAC signal

Have I finally found the Holy Grail of CD world?  Am I close ?

J-FET is a specific kind of low power field effect transistor hence my nick-name FET-ishizator. It is a bastard son of Lampizator.

Fetishizator is the World First fully transistor Lampizator.
As far as Lampizators go, noone before dared to push the boundaries of technology so far. Nobody went more close towards musical truth and engineering honesty. I am exploring the terra incognita. I am travelling alone to the dark side of the moon.

THE BIG QUESTION, which was bugging me ever since I opened the first CD and lost my DIY virginity, I was asking myself: why in the world all players use op-amps, some of them use tubes, but nobody uses TRANSISTORS ?????????????
A transistor seems to be a fairly innocent and transparent piece of silicon. It is no good for amps because it must pass many amperes, and tubes deliver high energy faster, but to amplify the 2 V signal of DAC - should be relatively easy.
Eventually I found in the Copland CD a nice discrete stage, quite complex to be honest but nevertheless great sounding. It was bettered by Lampizator though.  MARANTZ CD players have the famous HDAM (high definition analog module) which I immediately opened because it was concealed.
A quotation from my Marantz CD67 article elsewhere:
The output stage is original - Marantz TOP OF THE LINE HDAM to be found in all top players all the way to 8 000 Euro.
What is HDAM I really don't know. it is something MYSTERIOUS that is so cool they had to hide it inside shiny cans.
They hide it - I open - sez I.

HDAM outpud circuit in a can

tadadadadadadadadadada    drums rolling ...........
open kimono time !!!!


So the HDAM is an amplification stage consisting of 8 discrete transistors and 12 resistors and 5 diodes PER CHANNEL.
Very nice of Marantz to use discrete components not op-amps, hats off to them, but calling it a revolutionary proprietary high definition stage - is a BIT OF OVERSTATEMENT. Too much marketing BS for my taste.  To make things even worse - they still have one opamp per channel after DAC. And to make things EVEN WORSE THAN THAT - they have V out DAC type which requires neither conversion nor amplification, just a buffer.  Such output stage was an order of the day back in the times before opamps. Every kid in 1970 could do a stage like this on their first semester of electronics. So I do not consider it such a big deal.
Ken Ishiwata "invented " transistors in the same way I "invented " tubes.


I should patent SNIPIT and cover NOTHING - (air) - in the golden can and call it High Transparency Output Stage - HTOS.

Back to Fetishizator

As much as I liked the HDAM, (say in Marantz 7) I felt that they have overdone it.

If not HDAM, and not op-amp - what else can we do ?

opamp equivalent

This schematics above is just for your reference - op-amp  equivalent schematics.

Since I can't design transistors, I turned to the person of wisdom and experience: Mr Dietmar from Austria. He said that he feels a j-fet should do the job : shooting two birds in one shot: I/U conversion for TDA1541 and providing signal amplification.  Just ONE transistor replacing 27 transistors in average in an op-amp.

I took Dietmar's design, and I suspected it was again overdone for my taste. His schematics called for 4 amplification stages in series plus analog filter network.  I do not show original design because I went a different way.

As an experiment I built what Dietmar proposed and I listened to it for an hour - just two stages - Jfet SE amplifier and after - a FET buffer. Later - I built my own unauthorized variation - just one transistor.

One single ended pure class A zero feedback amplifier with field effect transistor (which behaves almost like a triode because the control pin - GATE - has high impedance. It does not consume current to drive the transistor. Gate behaves like a grid.

fetishizator J-FET
CORRECTION:  the j-fet on the schematics is really the "A" type. For the B - use 2k7 resistors in cathoides (ooops - in SOURCE)

I applied it to my best DAC - the TUBE-SATCH. I used TDA1541a/S1 dac and I took the supply from SATCH unused (well made indeed) supply block for the opamps - the 15 V DC.

I made special plugs so I can switch Lampizator and Fetishizator in 10 seconds.


The above prototype has two stages as per Dietmar's prescription, but only a half of it is used. I skipped the MOSFET buffer which was lowering just the output impedance.

The horror begins.

I spent whole night comparing my favourite discs and the bloody Fetishizator is so close to Lampizator that it totally scares me. One was winning, and another taking the lead many many times, like in today's volleyball game Poland Russia. When on jazz, pop, rock and fusion pieces the result was an equalizer, there was one area where the Fetishizator had a clear upper hand - that was ........................................................................... human voices. The transparent clarity and naturalness was absolutely mind-blowing.
The quality of TDA1541A was shining like never before. Naturally, the bass, especially lowest - was phenomenal as well. Space, 3-d, details, everything I can name is great.

This leaves me speechless. How is it possible?
And especially WHY NOBODY DID IT BEFORE? At least I haven't seen it done this way.

Overall, on a second day I decided I am staying with 6N2P tube stage because it sounds better to me as a whole, especially the rhythm and pace and energy is better by a small margin,  but the call is very close. I could live with the transistor.
For people who hate tubes or for those who do not appreciate them - the Fetishizator is an ideal choice.
After a week, I took the DAC to the friends house and tried it in a VERY sophisticated 70 000 Euro system and then I heard clearly that the 6n2P tubeis better without a doubt but J-FET sounds VERY nice indeed.
Probably a better choice of transistor, operating point and supply voltage - j-fet would sound even better. My prototype Fetishizator is a first beta version I ever tried.

Fetishizator Discrete Output Stage for I out DAC types.

All current output DACS like TDA1540, TDA1541, TDA1541A, Burr Brown PCM63, PCM58,  PCM1702, PCM1704, PCM1794, and Analog Devices AD1862  and many more - should benefit greatly from substitution of the typical op-amp with the Fetishizator. The difference between FET and tube is a question of taste and preferences, but Fetishizator against op-amp this is a knockout.

Benefits of using Fetishizator:

Down sides of Fetishizator

Not much of a downside, is it ?

After some thinking I decided to propose a new device: The world first opamp substitution Fetishizator - a funny way of mounting the Fetishizator on the opamp SOCKET to make it a 1:1 replacement for opamps in i/U conversion applications which is the FIRST opamp after the DAC chip.

OP-AMP Fetishizator a'la Fikus

In 95% of players, the first opamp after the DAC will be a double op-amp like 5532.
What we do,
  1. we remove the opamp,
  2. float the leg 1 (output) to isolate the feedback circuit (R and C from input to output)
  3. solder the new socket in place of opamp
  4. build the Fetishizator on the second socket
  5. plug the fetishizator in
  6. Install new solid RCA's
  7. wire the pin 1 to the RCA, mount the CAPACITORS (like a 2,2 uF MKP) directly on the RCA's.
  8. Wire the RCA ground to the PCB ground
  9. upgrade the capacitor supplying the leg 8 with 12 V DC with a better one like Blackgate, Tantalum or Oscon.
  10. Voila - It should work.
jfet Fetishizator
The J-FET is A type here. For B type - use 2k7 resistors instead of 820 Ohms.

This is the opamp base version of fetishizator - quick and dirty version without attention to neat soldering.

For the single opamps - like BB OPA-604 or AD825 - build a modified version.
If the DAC is wired to the second opamp  inside the double unit (pins 6 input, 7 output) - adapt the schematics accordingly. Some designers do so because the second half of opamp is easier to wire depending on PCB layout.
On my drawing I have both sides populated, but usually one double opamp serves one channel so you build a half of fetishizator only, one half per channel.

If you don't trust the existing power supply to the 12V pin (pin 8) (it may be contaminated with noise from clock, from DAC, from motors) you can float pin 8 and build your own supply of 12 V DC (or 15 V DC). That is probably a good thing to do.

fetishizator PSU

A DISCLAIMER: Users of transistor amps may be careful because the FET is transparent up to 700 MHz so it will amplify the inaudible noises which may upset your amps. I do not see a problem in my vintage system but your mileage may vary. Especially that if we use NOS mode and no analog filtering at all - noises may creep inaudibly.

A small note on me going "full circle"

Some readers who followed my other projects may be surprized, or even puzzled by the fact that Doctor Lampizator llikes the transistor. Some people may think that it is a joke.
Well, so what ?
Tubes are not a religion. Not for me. Tubes are not a dogma. I always claimed, that I like them as long as they do provide sonic edge. I could not care less if my best sounding device is a tube, a transistor, an op-amp, parrot guano or gaslight. Or Pentium processor.
I am looking for simple and elegant ways of achieving my target - uncompromised sound.
I insist - uncompromised - without any  limitation to low price, diy, budget or things like that. If money could get me sound, I would take a second job and save money for the Mark Levinson CD. But the key to pereformance is simplicity. Both tubes and transistor like J-Fet allow for ultimate simplicity - one acive device between I Out dac and amplifier.
So do not get me wrong - I am NOT CONVERTED to NORMAL CD players without tubes.
The J-FET is actually a STEP FURTHER - one step deeper into the world of simplicity occupied by tubes. I have to refine the circuit to match the tube quality, this one is not equal to best SRPP tubes.

At the same time - the J-FET experiment answered my question why nobody has done it before in HIFI gear?
Such a simple answer: FETISHIZATOR  including a high end power supply costs 2 Euro 25 cents (stereo) with premium parts.  So even after adding mohogany cheeks it is hard to justify a high price tag to the CD player.

I am planning many interesting experiments with the Fetishizator, and of course I will publish the results.

THE LATEST AND BEST design of Fetishizator 2,0 by Mr. Dietmar from Austria (DOWNLOAD PDF)  - he really tested it well and it is supposedly the ultimate Fet stage for I OUT DACS.
I have not yet formed my opinion about it so I publish it as Dietmars own proposal. I will try it asap. By clicking on the above link you will download PDF file with all info necessary to create fetishizator. File is over 500K in size.

Below I publish for quick reference the schematics from the PDF file.


Please note the TRIPLE caps are just bypasses to achieve beter timbres. You can use one cap if you want. At least to start. All cap values can vary significantly, especially up.

Meanwhile I remain,
Yours truly -  Doctor Lampizator in the state of Bliss.

Parts for this project