In this article we will finally make some REAL progress in dealing with a transport digital signal S/PDIF going to the DAC.
Did I  mention a green marker pen - ? NO
Do you think it is about VRDS clamp system? NO
Is it about belt drive transport ? NO (oh I am sure the belt helps a lot !)
Is it about the air pump suspension ? ? NOOOO.
Do you suspect it is about WADIA 10.000$ bargain transport?
Anybody? Golden cones? Silver/gold digital cables with plugs machined from one block of solid beryllium?

I have read hundreds of reviews of transport players, some of them costly toys for boys. I read in Stereophile, in Hifi Choice, in FI, in What hi-fi, in various Polish rags - and NONE of them, I repeat not a single article if memory serves me showed the scope trace.  The most basic fundamental test - see on the scope if square looks like square.
But NO. Nobody did.
If they didn't, I did. I took the scope and looked at over 10 different players, most of them costing A LOT of money back then when they were new.

I analysed over 25 schematics and I reached the conclusion that all these player's digital trace  and all schematics of outputs look BAD. Some of them better than others, some - so-so, and some just plain bad.

What particularly annoyed me is that the signal trace is so sensitive to small changes of the load - resistance, capacitance and inductance. That's why digital cables sound different from one another - because the transmitter is not optimized. It is weak. Its output impedance is 10 times too high or even more.

THIS IS ALL WRONG. No amount of "price" no wooden cheeks, no marble slabs and no siltech gold cables can make wrong S/PDIF signal good again.

Only dealing with the problem can do it. Thinking can do it. Engineering can solve a lot of problems. Lets try to design the damned S/PDIF from scratch.
In fact, perhaps the transport engineering and marketing has the HIGHEST content of bullshit from any other hi-fi product.  And almost no practical information.


(a disclaimer for people who take things too seriously: this is a funny experiment done just for fun and I do not suggest that you should do the same although you may.)
Ladies  and gentlemen (what Ladies ? Women don't come to these pages anyway) this is the WORLD'S FIRST - THE REAL DEAL - DIGI-LAMPIZATOR.
This is purely my own invention, my dearest baby. This is my greatest contribution to Hi-Fi so far.

MY REASONING was this: if all the problems which distort the signal on the way to the DAC are arising from too weak generator - the Philips SAA7220 chip - leg 14th, why not make what an engineer should and add a buffer. The chip will be happy working into virtually no load at all, just the grid. The square will be perfect as hell. Then the tube will have infinitely better output impedance (single hundreds of  Ohms)  and it will send the signal nice, pure, sharp , stiff and INDIFFERENT to cable and  plugs. No more bullshit about "quality" of transport and cable - costing a fortune. The quality means sending a proper signal not deploying voo-doo and mythology. To have a world's best transport does not mean buying Wadia, Levinson or Theta. It is about making a good player - a great transport by adding a DIGI-LAMPIZATOR.

I took the tube which is good for high frequencies - the Russian 6N14P, which has a frequency response good till 200 MHz. Our signal needs circa 20 MHz bandwidth so the tube is ten times "too good" for the job. Any other radio tube is good, The parameters like amplification etc. do not matter because it is a cathode follower. The audio tubes are no good because the frequency range is too low. There are tons of these tubes around and they are dirt cheap because nobody needs them today. I paid 1 Euro for 5 tubes brand new NOS. TV tubes are good too.


I created a simple mono triode amplifier in cathode follower.
The anode supply is circa  90 V as should be, the heaters are just 6,3 V AC, no rectification. The cathode is a 75+75 Ohm resistor divider (150 Ohm cathode load. Output is a 1,5 V DC square from 75 Ohm resistor. Fully aligned to 75 Ohm characteristic impedance of the S/PDIF format (and cable).
After assembling the DIGI-LAMPIZATOR I connected the leg 14th of SAA7220p/B to the tube grid directly. I added a 15 K resistor to ground the grid and to load slightly the transmitter chip.

BINGO. The square wave is PERFECT. It beats the stock signal without sweat. The difference on the scope is night and day. There is no ringing, no rolloff, all is just excellent. Forget about the expensive transports. I have yet to see the output trace as clean as this one!

Correct me if I am wrong, nobody ever did something like that before.
The cost of the tube plus socket plus 3 caps is in total in the single Euros. The transformer adds 20 Euros. But this makes ANY PHILIPS / Marantz or Grundig CD PLAYER WITH SAA7220 AN ABSOLUTE CHAMPION OF TRANSPORTS. Add one  os-con in 5V power supply of the SAA7220p/B  chip, add a super-clock- and you have the best transport that any money can buy.
Some people asked me why is DIGI-Lampizator necessary if in the Transport article I demonstrated that resistor tweaking and transformer removal can give already grat results. The answer is that this signal was good without load. Any different cable, different dac, longer cable etc would distort the signal again. Because it was produced by the source which has high output impedance, low damping factor and no possibility to hold square stiff.
The lampizator makes signal stiff  - will be MUCH more tollerant to variances of what is AFTER the output.

I will play a little with the system and I will optimize the circuit and I will post then the final version and the sound description. I will compare two identical players, one modded and one stock.
The first impression, before comparison to stock player, is very good. It is easily the best transport I ever had at home. Difference is audible.
Things became more solid, the sound is very tight and lively, but the most shocking aspect is the hallucination thing. The accoustic of recorded event  more that ever before produce believable realistic soundscape.
My guess is that because the datastream is mono, carrying left and right information alternating in the data packets L and R , The timing to send them both to stereo DAC is critical. When the timing is really perfect, the sound of L and R becomes better synchronised. Our brain is fooled better - it can detect time differences between L and R  as small as single milliseconds - thats how we can "see" with our ears where the fly flies with eyes closed. Left and righ ear detect differences in timing of sound arrival to our ears. With precise digital signal - time allignment of L and R is much improved. The pleasure of listening increases by a factor that is easy to detect in few seconds after hitting PLAY.

I will go to friend's house and compare my transport with world's best machine in my opinion - Audiomeca Mephisto (also employing Philips CDM mechanism, although only low model number 4.)


My schematics - first revision but already working very well.


The test drive before making everything nice and neat. (short leads are critical)


Signal tapping from the SAA7220p/B chip - leg 14-th.

Original signal from Grundig 9009 Fine arts and the sameone  -really  identical - was from Marantz CD94 MK2. Both have Philips CDM1 mk2 mechanisms but very different schematics. Both use SAA7220p/B for  S/PDIF.

The best trace by far was from Sony 555 ESD but that is a really good machine all around.
I have over 15 different traces waiting to be posted here below when I crop the jpegs.

Digi-Lampizator trace of the same machine pictured above - the Grundig Fine Arts 9009. Just look at the level of improvement.
pp voltage level is 1V

Try to beat that! Anybody? Hey CEC are you there ?  Accuphase ?

FInal word and conclusion about digi-Lampizator:

This experiment was fun. Tube can work as digital transmitter. System is very stable and provides a lot of pride of ownership.
WHAT WE ACHIEVED SO FAR: We learned, that REGARDLESS OF THE PRICE - be it 20 Euros or 2000 - all players have basically the same kind of S/PDIF output. They use same cheap transformer for separation which corrupts the signal and which is unnecessary.
Regardless of the price, all players can become good transports if the signal is cleaned up. The super-clock will help to avoid jitter - data timing problems, as well as it eliminates the high frequency modulations of signals, power supplies and earth in the player. Superclocks are good to have.
On top of that the  digi-Lampizator gives us clean and stiff signal, no more problems with cables distorting heavily. This output will drive any cable, even a totally wrong lamp zip cord. No more need for exotic silver Gucci cables. Of course Gucci cables are nice to have.
The combination of clock, stiff S/PDIF buffer and some anti-vibration measures give us all we need to have good transport. Adding a super DAC with lampizator takes us to Nirvana right away (source wise of course)

A side comment - Sony and Kenwood have best stock form signal traces - no wonder - they use transistor buffers doing just what my buffer does. But having tube output is so much more cool !!!!

but for those pragmatic people I have a solution! here comes ...


As usual with transistor technology, I referred to someone else who knows this "sand" technology well.
Mr. Dietmar  suggested his beloved J-FET to act as my tube - as a cathode follower.

This circuit is easy to build and easy  to fit inside CD player. It will remove the load seen by the output chip S/PDIF (making trace much sharper) and it  will make output impedance significantly lower. The circuit will drive any cable and any DAC out there without sweat.
Remember to use twisted pair from CAT5 cable or just screened coax to take the signal to the output socket.

Here is the schematics:




Transport article: HERE

SAA7220p/B datasheet: 

CD clock article: HERE


This is interesting "digital with tubes" clock for CD from great company Prima Luna:

The "must read" link from Holland - Marantz and Philips information page


LampizatOr shop with pars and kits for DIY projects
Lampizator finished products (not for DIY)
Amplifiers page
DAC pages
Music server and transport page
SILK AC filter