With my resent battle with Shelter and the off the FM session analog renaissance I am playing a lot of records and there is one observation I would like to make. I feed all my 3 “better” tonearms into the “End of Life" Phonostage and I can’t not to mention how beautifully the Phonostage behave and sounds, in fact it is beyond beautiful, it is truly extraordinary.

I usually is very bitchy about the performance of audio elements, would it mine or others. I know well where my own audio element slips. However, with the “End of Life" Phonostage I have literally no single point where I would have an issues. It just does phenomenal Sound and it turned out to be phenomenally friendly and accommodating in my setup. As far as I concern the “End of Life" Phonostage is truly deserves it’s name…

drdna wrote:

What specific objectives did the air caps address in the circuit? You refer to the tempted virtue sound but I am unsure as to the goals that you were trying to achieve with this circuit alteration?

 I what wrote about the air caps in the thread: “Where are our good phonostages?”

The genuineness of this Paravicini circuit is that he use feedback to plate – or to vey high impedance – and in this situation it revilers very small values of capacitance to write the necessary RIAA curve. In fact the curve is written not by the feedback but by the Miller capacitance of the tube. The 12AX7 was designer as audio tube, it is a radio-frequency rube  and therefore is has very high Miller capacitance, the capacitance the otherwise conceded as parasitic but the smart Paravicini put it actually in the beneficial use. So we have a circuit with “hidden RIAA”.

Now Paravicini adds the very light touch of capacitance into feedback to make the Miller capacitance to work what it shell work. The values are very small s the capacitance in feedback sort of multiply the tube’s own Miller capacitance. The series capacitors in feedback, regardless of value and types are very bad. In fact a feedback cap is the more auditable them loading, coupling, cathode or any other cap. The coupling cap for instance is charged with DC on both sides and the AC. What cap is? It is the sequence of conductive and non- conductive surfaces where non- conductive dielectric acts as an abrupt termination of AC flow. However, the dielectric is not a perfect dielectric and has some free electrons in itself that can care the signal.  This abrupt termination induces a microscopic force in the dielectric that make the dielectric to move, and by virtue of it creating variable reflections of transmission termination. So, that coupling cap has already charged or pollarded with DC on both sides and the cap’s conductors have already biased or physically oppressed the cap’s dielectrics. In case of cap sitting in feedback there is no DC (in second cap) and the dielectrics are not damped. Furthermore the re-polarization of dielectrics does not happen at non-auditable frequency but at very much auditable frequency – the frequency of the correction. I do not even mention that dielectrics experience different behavior of  electro- mechanic induction at different frequencies…

 So, how to create a better condition on this situation? The concussion is to get rid of dielectric all together. The non-dielectric caps: air or vacuum are very large for a given value but in this Paravicini case the values of the caps are so small (100pf and 300pf) that the air caps could be called for the duty.

I do not say the in the “End of Life Phonostage” the air caps is something that made all sound. The ET SU-2 transformer I think is the very heart of this Phonostage and 80% response for the corrector’s sound. Still, I think the air caps were very contributive as well. I did not listen the “End of Life Phonostage” with mica caps but I did listen and did “evaluate” the vintage mica, the polystyrene and air caps in context of my 7788-7721 phonostage.  (It uses the absolutely the same Paravicini’s ides of feedback only uses7788 pentode in input and has just two stages). The result was very superbly convincing and perfectly proved the theory about the fundamental advantages of air caps.

Paul S wrote:

Romy, doesn't Tim de P also use this cool Miller capacitance idea in his never-mentioned "high end" tubed corrector?  Also,  do I remember reading that he runs both channels through the two halves of the same twin-triode 9-pin tube?  Is this something you changed when adapting two units for stereo?  BTW, I have never heard the P88, or whatever he calls it.

Well, it was a long debate in the past if to keep my “End of Life Phonostage” as it use to be: six tubes, having 3 halves running right and left channels and keeping other halves half “cold”. I eventually decided to go for just 3 tubes running right and left on the opposite halves of the same twin-triode. I very careful considered the cons and pros and consulted with many people. I still do not know if my decision was “correct” but below is my rational. Subjectively I think that I did detect some very negligibly minor advantage of six tubes version but it was so none-conclusive and so non indicative that I discarded it as a margin of the experiment.

For using halves of the same twin-triode:

·  Less costly tubes.
·  Less inner chassis hit.
·  Less filament AC inside the phonostage chassis
·  More compact and elegant layout
·  Inability to reuse the tubes buy flipping them to another side when the current cathode is gone
·  The tubes of the right and left channels come from the “same barrel” (gas contamination, cathode poisoning etc)

Against using halves of the same twin-triode:

·   Alleged crosstalk

I truly do not know any other considerations then crosstalk and here how I thought:

According to the papers the crosstalk in the twin-triode is around 90dB-100dB. It is VERY high number; do not forget that cartridges have 20dB-30dB. The numbers of crosstalk are mystery for me and I was not able to see how extra 10-20dB of improved crosstalk do better for imaging subjectively. I figured that 90dB-100dB if electrical separation in twin-triode is too high do not worry about it. The 100dB of separation even my Macondo can’t handle as my horn pick the pressure from room and have their diaphragms to act as microphones. I have my amps off and might talk at my room in normal voice, having the channel loudness-to-pick- modulation meters on Macondo running a full scale…

So, I think and feel  that in practical application the theoretical crosstalk in twin-triode is way offset by the advantage I enumerated above.

To close the book on the correctors subject I put some comments in a dedicated page in “My playback” section.

http://www.goodsoundclub.com/EndOfLifePhonostage.aspx

Here is a Thai guy looks like built my “End of Life Phonostage”

http://www.kaponk.com/node/715

I do not see nether input choke or air capacitors in correction chain. The most important I have no idea what step-up transformer he used and what kind sound he is after. I am sure he can read schematic and to solder but it not so important skills. I do not read Thai but from I understood he did not talk about sound of this thing in his article.

It is always there is something that poisons everything. It is last night in my Boston apartment, a night before the final big move and I was in the middle if heavy packing. Suddenly as lighting stroke me: I was moving my moved audio equipment from one bedroom to another bedroom, letting the carper guy to do his job, as suddenly I realized that I did not move my End of Life Phonostage. All my equipment was sitting in one bedroom and all of it has one way or another some kind of handles. The End of Life Phonostage has no handles of any kind and I do remember that whatever I moved I used handles. I dropped everything and rushed to my new place and for sure I did not see my phonostage.  I do distinctly remember that I move it, right on the seat of my car, driving very gently in order do not fuck up the air capacitors, and now it look like it gone. If it so then it is VERY sad!!!

I heard that during the move the things walk. Over the last 2 week I have contractors working in my new place. I do feel very confident and comfortable about them, still where the hell my phonostage? I am sure no one need it beside me, particularly without power supply, still the bedroom is the only room where all equipment sits and the phonostage is not there.  If it were lost then phonostage itself is not a big deal but it had the Expressive Technologies SU2 transformer in it and this is non-replaceable. This feeling of lost phonostage really poisons my entire getting new house ceremony and I am very upset…

Is it God punished me for the overly ambitions name of the phonostage – “The End of Life Phonostage” or is it some kind of sarcastic message of him for my arrogant treatment of the phonostage as the last statement of pnonocorrector?  I do not know.  I was driving back to Boston to continue packing and was thinking that I would need a new phonostage – I so do not want to deal with phonostages anymore…

Anyhow, I got home and I am not in the mood the pack. A few thousands LPs left to be packed but I have no feel to touch the vinyl.  Fuck it, I will ask the movers to pack it tomorrow, I am in the moaning for my “The End of Life Phonostage”…

Romy the Cat wrote:

...This feeling of lost phonostage really poisons my entire getting new house ceremony and I am very upset… Is it God punished me for the overly ambitions name of the phonostage – “The End of Life Phonostage” or is it some kind of sarcastic message of him for my arrogant treatment of the phonostage as the last statement of pnonocorrector?  The Cat

Dear Romy,

I truly am sorry to hear about your loss. You certainly do not deserve this. If it is any consolation you might like to check out

the following website for an insight into the Bent transformers in relation to Expressive. Not sure how much credence you give to the 

info but you have  to start somewhere.

http://www.high-endaudio.com/RC-Step-ups.html

regards,

Gordon 

Reggie wrote:

Hi, Reggie here. Sorry Rakesh, but I have to say; what a smug tosser's answer. What the heck does God and Starving children have to do with his phonostage? Is he supposed to feel guilty for being upset about it being gone and why would you laugh about it?? Really Sorry Romy.. Hope you find it. Really I do...

AlexBerger wrote:

Hello Romy, I just have build the postage used your "End of Live"  scheme and Altec step-up transformers. http://picasaweb.google.com/alex.berger73/Phonostage# I have original EAR. After of 100 hours of working, the new Phonostage  sounds more dynamic, transparent with much better separation. One problem is 100Hz hum. I did hitter supply filter with too weak ripple filtration: C-L-C (13200uF-3mH-6600uF). Now I going to rebuild  hitter supply. Is any difference in sound of semiconductor stabilization filtration, C-L-C-L-C or L-C-L-C filtration.

Alexander, are you sure that it is 100Hz hum but not 120Hz hum? Even I do not like and tend do not use CLC supply for filaments but your hum most likely is NOT due you your PS. The 13200uF-3mH-6600uF is enough to drive the ripples low and kill the hum.

It is VERY difficult to debug any devise “over the phone” in search of hum. Hum is most likely some kind of ground loop and you need to find it yourself. Pay extra attention to the wiring diagram of the old Altec step-up transformers. I have some of them (Altec and EV) and they are in my view need to use extra shielding and they are very difficult to make them to be quit.

What you need to do for sake of simplicity is take a wire of 2 feet long and begin to short different sections of your new pnonocorrector grounds. Soon on later you will find the location that after they were shorted minimize the hum. This will give you an answer where the hum comes from. I would do it separately for the pnonocorrector and then what I find the absolutely silent configuration, only then I would put the transformer to the game.

Also, considering the proximity of the air caps to the filaments I would VERY strongly advise to use twisted pair for filaments. The twisted pair is very singly but it is VERY effective as it is self-shielding. You can detect if the hum come from air caps by disconnecting them. Also use the “disconnecting trick” to see if the problem comes from the filaments. When you turn off the corrector off then it will be still a second or two operational. You will be able to hear how the hum will change in the moment of disconnection. Remember, what you disconnect the B+ still there and the tube is still hot but there is no filament voltage…