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05-31-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 26
Post ID: 7492
Reply to: 7480
I am semi-ecstatic; my vinyl will be back soon…
and I hope it will be up to the level … of FM in term of enjoyments. Anyhow, the phonostage is the already pack up in the chassis and running. I dropped the B+ supply to 270V and the R1 restore to 120K, keeping the 100V on the first plate. I can’t wait to listen this thing tomorrow, it shell be very-very interesting and long-expected.

EAR834PT.jpg


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-31-2008 Post does not mapped to Knowledge Tree
Reggie
Posts 13
Joined on 05-08-2008

Post #: 27
Post ID: 7500
Reply to: 7492
MFA Systems Phonostage

Hello Romy

This is my first post.

Did you take courses in electronics and mechanical engineering or have you learned yourself outside of a structured environment? I am very interested to become proficient in working on/modifying my own electronics. I would enjoy spending time at the workbench such as the one pictured above.  

Reading many posts on your site has caused me to think about my system. I'm facinated by horn systems and have heard several that were compelling in key respects, the ability to use a DSET such as your Melquiades amp being one. One the subject of a 'final' phonostage, my own is one of the three MFA Systems MC Reference prototypes built for CES in Las Vegas. This one, housed in an MFA Luminescence chassis is the ultimate of the three. It differs from the production version of the MC Reference in several ways. It is hard wired throughout and uses ECC88s, 12AX7s and 12AU7/AT7. The phono stage is battery-powered. I've included some photos for you to see. It is currently in need if repair. Bob Hovland took a quick look at it and identified two caps that needed to be replaced. they have been removed so you may notice them missing in the photo. This particular phonostage has the magic you talk about.

Romy I cannot upload the images. I tried using the 'insert images from gallery' button. Can you tell me how to do this correctly?
05-31-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 28
Post ID: 7501
Reply to: 7500
Good for them.

 Reggie wrote:
Did you take courses in electronics and mechanical engineering or have you learned yourself outside of a structured environment? I am very interested to become proficient in working on/modifying my own electronics. I would enjoy spending time at the workbench such as the one pictured above. 

Nope, have no structured training but juts a respect and discrimination to results, common sense and an opportunity of asking right questions. What I would like to note is that I have no specific pride of even interest in doing my own electronics and if I have somebody why would do it for me I would joyfully not have even a solder gun.

 Reggie wrote:
Reading many posts on your site has caused me to think about my system. I'm facinated by horn systems and have heard several that were compelling in key respects, the ability to use a DSET such as your Melquiades amp being one.

Reggie, I would disagree. DSET is not a key in horn systems. DSET is a way to fight with intrinsic limitation (or I would say complication) of SET topology. Horns by nature do not need DSET as they are harrow bandwidth devises…

 Reggie wrote:
One the subject of a 'final' phonostage, my own is one of the three MFA Systems MC Reference prototypes built for CES in Las Vegas.…This particular phonostage has the magic you talk about.

I never heard this phonostage but if it has that “it” then it is good for  them.

 Reggie wrote:
Romy I cannot upload the images. I tried using the 'insert images from gallery' button. Can you tell me how to do this correctly?

I really do not know – it looks like works top me. “Insert image from Gallery” is the yellow button right next to the printer buster in your reply interface. If you run some kind off the wall browser or OC then you can attach image to post.

Rgs, the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-31-2008 Post does not mapped to Knowledge Tree
Reggie
Posts 13
Joined on 05-08-2008

Post #: 29
Post ID: 7502
Reply to: 7501
Photos of the MFA Systems MC Reference
DSC01144b.jpg

DSC01145.JPG
05-31-2008 Post does not mapped to Knowledge Tree
Reggie
Posts 13
Joined on 05-08-2008

Post #: 30
Post ID: 7503
Reply to: 7502
A few more
DSC01146b.jpg

DSC01145.JPGDSC01150b.jpg
05-31-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 31
Post ID: 7504
Reply to: 7492
OK, it is over. Some preliminary follow ups.

I spent a bigger part of day today to finish the “End of Life" Phonostage, there were many things to do but it is now over. Done! Complete! Amen! I it closed up and sat in it’s permanent place.

EAR834PT.jpg

A few observations looking back. First, I spent a LOT of time trying to fine tune the RIAA curve. I use the test LP with 20-20K sweeps. I use Jim Hagerman’s contra-RIAA little tool, driving the RTA and scope from generator. I use my Wavelab’s phenomenal FFT meter driving the Phonostage into Pacific Microsonics analog-to digital (this A/D calibrated mind-bogglingly well). I usually use the Wavelab’s FFT and Phase meters to help myself to setup cartridges – very covenant. Anyhow, to my displeasure I learned that  the contra-RIAA devise was slightly off at HF, so I end up not to use it and used other means.

In the end of everything I was able to get very nice response. The response is nice and flat with 0dB at 18.1Hz and 0dB at 15.600Hz. It has plus 0.2dB from 1500 to 3500 which I feel is not a big deal. (Juts for my future reference: the values of the feedback capacitors have without de-soldering capS from the circuit are: 110pF= 136.2pF and 330pF=372pF)

 I found a very good grounding schema and the self noise this corrector of 26db+48dB=72dB gain is better than good – it has absolutely no noise. The previous adaptation had no problem but this one took noise even further – there is no difference for the system between CD input and phonostage input, and do not forget that we are taking about 109dB sensitive system.  I presume that my new construction techniques (mounting everything short point-to-point on a think copper plate that used as a ground terminal) do help. What I also detected over the second part of day playing the corrector that it looks like the gas regulation helps with good with electricity. Apparently the gas tubes shunt all power line dirt – a promising sign.

Sonic results. It is hard to say. I feel that there is no sonic difference between my former version and the new one, the new phonostage  is too fresh, the caps, the PS, the disturbed Dominus cables the total assembling - perhaps I need to return to the subject of sound after 500 hours. The new phonostage has the following changed compare to the former one:

1) Fix biasing on the second stage instead of the former automated
2) Different filament and anode PS, the anode supplies are gas regulated.
3) Better construction techniques  (the former version was my very first DIY Audio attempt since I began practicing the  US version of High-End Audio)
4) V-Cap coupling capacitors between the first and second stage
5) More immediate connection between the ET2 transformer and first grid

I did not study or observed the incremental changes, let see how it will turn out all together.

Preliminary conclusion: very good. It looks like the essence of the ET+834PT was not lost (that what I was afraid and this is why I built a new corrector and kept the original intact – just in case). The new corrector did not developed it’s full bass yet but I know the Nichicon caps and the disturbed Dominus – it shell come later. All together the sound as I expected – three is nothing alarming at this point. Some unique ET+834PT quietly are still there. For instance the ET+834PT is the only know to me phonostage that is capable to play  (if needed) without HF.  I mean any good phonostage I tried threw very high quality HF, demonstrating that analog HF might be very-very good. Only Boulder 2008 phonostage was a minor exception that was able to throw non-presumptuous HF up to a degree. The ET+834PT takes this approach to extreme – it has no HF at all and it pitch HF into the game ONLY when it is necessary. You listen it and it feels at beginning that there is not enough HF but you add .5dB and realize that it is how live Sound sounds. There is no HF in live sound; there is Space but no HF itself. ET+834PT does the necessary HF’ space tricks without actually making HF themselves. I can go on in many other specific distinctive characteristics of the ET+834PT but it is not my objectives at this point. The important is that the new procurator looks like preserve them all – God bless the smart Tim de Paravicini’s design of amplified Miller capacitance and feedback to high impedance.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-01-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,130
Joined on 10-12-2006

Post #: 32
Post ID: 7505
Reply to: 7504
"Lack" of HF, etc.

The "lack" of HF is definitely one of the wonderful things that makes one think of spending 30K on a phono stage.  Glad to hear you are "suffering" a similar "dirth" of HF [noise] with your DIY corrector.

I wasn't going to say anything, but I wondered up until I saw this "finished product" photo if you planned to run the 12AX7s horizontally...  That would have been "interesting"...

My "modern" Teflon composite caps did not take long at all to establish themselves; nothing like the "premium" electrolytics, which not only take a long time to sound decent but they also "revert" if you don't run them for a while.

Do I remember that Tim d' P. also likes to use one twin triode tube for two channels?  I am "iffy" on this conceptually; never tried it.

I know you are all stoked with FM benefits for some time now; but surely the musical treasures on vinyl are enticing, not to mention the potential?

I have also read your thoughts on VTA/SRA, but if your corrector is "articulate" then you must be pretty much stuck, needing to get it fairly close?


Best regards,
Paul S



06-01-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 33
Post ID: 7506
Reply to: 7504
“End of Life" Phonostage: what is next?

OK, here are some follow up thoughts after the completion of the project. I am sure I will burn it for a month or so. I think everything will be fine, I do not expect any issuers technical or sonic. The way how the entrance to the corrector done it is very easy to replace the 4 cable from 4 arms without replacing the cables. As I told I did found a very interesting “second phonostage” (very convent one) that I was planning to use with my other arms but if it is so convent to flip the cable I wonder if I go for the second phonostage. I still have my former 834PT and the 7788-7721 phonostage available, all performing perfectly fine … later on I will decide if I willing to use them.

There is one area that I would like to explore with my “End of Life" Phonostage after it will settle down. The very smart fist stage in there will be stay as is, also I have no interest to experiment with second stage. The last stage is just a cathode follower. In my ultimate buffer experiment I never was able to get a good transparency from tube buffers, so I am intending to put there (as an experiment) a transistor instead the last 12AX7. I am not planning to change anything but juts to take a male 9-pin tube socket, solder in there a transistor that is able to care 300V and juts plug it and play. It is possible that with SS output buffer I might get different result. What kind result I would like to get? Sonically I can’t at this point to identify what I would like to get but measurements –wise I would like to drive the low range to sub 8Hz at 0dB. It is not that my hands are itching but I feel that at line level SS buffer shell do better than a tube…. If someone know any good sounding low power (5-15mA) transistor at 300V-350V then please let me know. So far I was proposed MPSA42, ZTX458 and suitable but too powerful MJE340. As a reader of my site suggested:

“The NPN will reduce the output impedance => will affect the Riaa feedback increasing the gain by ~1db@20Hz and ~0.5db@50Hz (in your setup will be quite noticeable). A quick and dirty remedy is to add a resistor (1k5-1k8) in series with the emitter of the NPN. Although this could be useful to reveal the sonic properties of the NPN it may also defeat the trouble”

I still consider the options how to make the experiment with buffers substation clean and methodologically kosher. Sine I have absolutely no knowledge at SS any recommendation are welcome via the site or direct emails.

Rgs, Romy


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-01-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,130
Joined on 10-12-2006

Post #: 34
Post ID: 7508
Reply to: 7506
Hybridizing

The SS out does calm/quiet/clear things considerably, but there is a price for that clarity, as I have reported.

You probably already looked into JFET?

Do I "remember" that you had a stash of exotic adjustable air-core caps?  As you can tell from the question, I have not tried to run the math, but would the "trim-able" cap give you enough range to dial in the network?

The last time I ran into this, I think wound up with Audio Note tantalum R, which can do "hard" better than wire or carbon comp.  Vishay was "too much" there, as I recall, like on plates.

Best regards,
Paul S

06-01-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 35
Post ID: 7509
Reply to: 7508
I love it!
I actually woke up today at 6AM, check all settings on my arms (after a few month of not working), demagnetized the needles and was spinning records all mooring. One of the benefits that I got with new phonostage is that the grounding patters for all arms are identical and I might absolutely painlessly to flip between the arms. This morning I play mostly mono records driving from SPU Mono. I just love the result, I truly do. Funny-funny I removed yesterday my reference for this phonostage, selected by years of use, Telefunken –Sylvania-Telefunken tubes combination and put there cheap and no particularly good sounding 12AX7 (for a next 30 days I am not planning to shut this thing down). The corrector still sounds very pleasant and very much listenable and extremely peaceful for my iterated and sick audio mind. Very cool!

EAR834PT.jpg

 Paul S wrote:
Do I "remember" that you had a stash of exotic adjustable air-core caps? As you can tell from the question, I have not tried to run the math, but would the "trim-able" cap give you enough range to dial in the network?
Paul, it has nothing to do with math. It is one of the unlikeness of the Paravicini’s design. He runs feedback not to cathode but to high impedance of plate. So it is very high impedance and very low capacitance feedback (contrary to usual RIAA feedback with low impedance and high capacitance). Moreover he uses current feedback (cathode resistor) on the fist tube to raise the first stage plate impedance. Then he unites the miniature capacitance of the feedback with Miller capacitance of the first stage and et then let the combined capacitance to be amplifier by the second stage. Very slick, pay attention that the first stage Miller capacitance, the minute values of the feedback caps and the capacitance of the entire assembly are no consider in this design as parasitic but actually used for a purpose. In a classic RC design you would need relatively large caps to write the RIAA cure and you will be way beyond the range of no dialectic caps (air or vacuum). In the 834P design the feedback caps are very small values: 110pF and 330pF that allow using “nothing” as dialectic in the caps. The only thing that I would consider from here is to use doted symmetric air caps where the signal does not go over the movable contacts or the body of the cap. The only place where I see such air capacitors was inside my Rohde & Schwarz Tuner

“Rohde_Schwarz_caps

but I clearly understand that I will never found such caps…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-03-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 36
Post ID: 7526
Reply to: 7509
If I may be a litt;e suggestive.....
I have some ZVN0545A mosfets here for exactly that purpose of replacing cathode followers. You may like to try this starting at 2mA (250V supply, 125k biasing resistor). Did you or Dima try Soviet SSG silver-mica for the first coupler? I am using 0.175uF items for excellent results though I haven't compared to teflon.

The 834P circuit is not designed for low distortion (probably why Guy dislikes it) but for "listener-friendly" natural harmonic decay. I guess that accounts for the magic and I too have a corrector for life, though now with vintage moulded silver mica caps in place of the air vanes. My shipment of tuning caps from Ocean was destroyed by our paranoid customs!!!

Brian.
06-03-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 37
Post ID: 7527
Reply to: 7526
Mica, distortions, MOSFET and the Ocean State.

 Brian Clark wrote:
I have some ZVN0545A mosfets here for exactly that purpose of replacing cathode followers. You may like to try this starting at 2mA (250V supply, 125k biasing resistor).

Brian, and how do you find your MOSFET behaves compare the 12AX7-based cathode follower?

 Brian Clark wrote:
Did you or Dima try Soviet SSG silver-mica for the first coupler? I am using 0.175uF items for excellent results though I haven't compared to teflon.

Nope I did not try them. I have 5-6 different versions of silver-mica though and I prefer air caps. I do not know what Dima tried. He has the same corrector with Ocean State’s air caps only in place of the first 12AXy he uses Russian nuvistors

 Brian Clark wrote:
The 834P circuit is not designed for low distortion (probably why Guy dislikes it) but for "listener-friendly" natural harmonic decay. I guess that accounts for the magic….

This is big question but I would have a lot of to say. I do not think that 834P circuit is designed for any specific distortions.  I understand “distortions” differently.  You might read my Macondo Page that gives an idea how I see distortions….

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-04-2008 Post does not mapped to Knowledge Tree
deemon
Posts 23
Joined on 05-25-2004

Post #: 38
Post ID: 7529
Reply to: 7526
SSG
Brian , I never tried SSG cap in phonostage . SSG has a good reputation ..... but I'd prefer teflon for coupling . Mica caps , even good ones like SSG , seems too "bright" for me , but teflon sound pretty neutral .
06-04-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 39
Post ID: 7530
Reply to: 7527
Of mosfets, caps and distortion.
 Romy the Cat wrote:
Brian, and how do you find your MOSFET behaves compare the 12AX7-based cathode follower?


Romy, I have yet to try. Only got them on recommendation very recently. They're cheap enough to try in a B9A plug-in without altering anything in the circuit, though perhaps a good idea to add a carbon comp resistor on the gate. I'll try and find one of those plugs in the garage and give it a go.

I have 5-6 different versions of silver-mica though and I prefer air caps. I do not know what Dima tried. He has the same corrector with Ocean State’s air caps only in place of the first 12AXy he uses Russian nuvistors


Yes but you can't use an air-cap as a coupler in that circuit. The SSGs are a whole lot cheaper than VenHaus's V-Caps.

I do not think that 834P circuit is designed for any specific distortions.


Whereas I do. deParavicini's worked on designs in Japan over several years and became familiar with the  research going on there in the Seventies which culminated in identifying the HD decay-spectrum as a key indicator for "musicality". I.e. a monotonically decreasing level as order increased such that each HD  component masked the following component. This occurs naturally in a single triode operating under normal conditions. When I simulated the 834P circuit two things were obvious - the level of THD was high but the aforesaid decay spectrum approximated that of a single triode valve.

For what it's worth and acknowledging it is part of a bigger picture of course.

Brian.
06-04-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 40
Post ID: 7531
Reply to: 7529
USSR SSG
 deemon wrote:
Brian , I never tried SSG cap in phonostage . SSG has a good reputation ..... but I'd prefer teflon for coupling . Mica caps , even good ones like SSG , seems too "bright" for me , but teflon sound pretty neutral .


Hello Dima. In my application it is the first-stage coupler followed by an oil-type in second coupling position. This seems to work very well. However, I might try SSGs in both positions to hear if brightness prevails to a distracting degree. It would be interesting to hear SSG vs VCap. The Ven Haus should be the clear winner but just how clear would be .... interesting.


Brian.
06-04-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 41
Post ID: 7532
Reply to: 7529
USSR SSG
 deemon wrote:
Brian , I never tried SSG cap in phonostage . SSG has a good reputation ..... but I'd prefer teflon for coupling . Mica caps , even good ones like SSG , seems too "bright" for me , but teflon sound pretty neutral .


SSG vs V-Cap would make for an interesting comparison Dima. Of course we would expect the V-Cap to be the clear winner but maybe something valuable would be learned? Especially for poorer aspirants.

I have yet to try SSG in both coupling positions since the largest single value I have is 0.2uF and I believe that is the largest manufactured.


Brian.
06-04-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 42
Post ID: 7533
Reply to: 7532
Question for Dima re 2nd stage biasing.
Dima, did you & Romy experiment with contact-potential biasing of the second stage before settling on fixed-biasing? My Spice files are on my old computer and effectively lost else I would run simulations out of curiosity.

Brian.
06-04-2008 Post does not mapped to Knowledge Tree
deemon
Posts 23
Joined on 05-25-2004

Post #: 43
Post ID: 7534
Reply to: 7533
Fixed bias
Do you mean a battery bias , Brian ? We didn't try it because of 1 V bias voltage - I don't know if the battery with this voltage does exist . I know only 1,5 V and 1,2 V cells ...... maybe using some chemical reactions we can obtain 1 V or little less , but I don't know how to do it ..... Anyhow , if we use a battery in the grid chain - we still need a resistor ( 2 M ) after the coupling capacitor , and we must add 2 contacts of the battery socket and the battery itself . But the fixed bias , as I think , is a more suitable solution in this case - we have the most simply sound chain from the plate of V1 to the grid of V2 , and the short grounded cathode of V2 . I think that it's the best idea ...
Dima
06-04-2008 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 44
Post ID: 7536
Reply to: 7530
The stunning sound of the phonocorrector.

 Brian Clark wrote:
Whereas I do. deParavicini's worked on designs in Japan over several years and became familiar with the  research going on there in the Seventies which culminated in identifying the HD decay-spectrum as a key indicator for "musicality". I.e. a monotonically decreasing level as order increased such that each HD  component masked the following component. This occurs naturally in a single triode operating under normal conditions. When I simulated the 834P circuit two things were obvious - the level of THD was high but the aforesaid decay spectrum approximated that of a single triode valve.

For what it's worth and acknowledging it is part of a bigger picture of course.

Brian, that is very interesting and I did not know it about Paravicini. Was it intentionally or now is a different matter… Whatever it is it works…

I am going tell you, Brian, and to other something ease that might blow your socks off, if you are associated or talk with Paravicini then feel free to forward this message to him. So, what would it be?

Well, the “musicality” and “humanity” of this Paravicini-based phonocorrector (whatever reasons are) turned out to be so astonishing that it becomes dazzling. Do you know that my new 834PTF phonocorrector has an ability to actually override the musicality of amusical medioum and to recover/recuperate the poisoned Sound? Do I sound too hallucinogenic, do I? The reality is that I am not hallucinogenic and that I very clearly, cognitively and rationally see the things. Let me to explain.

First of all what I’m saying does not mean to convince anybody. It is internet, my site, and I can run my month on any subject with any degree of credibility and trustworthiness. However, I do not think I was ever was spotted lying or to be deceptive (I can testify that I was stupid in some occasions but it was not deliberate and was just due to ignorance). So, I’m not lying now – the “End of Life Phonostage” does have some internal magic that makes Sound passing via the phonocorrector more interesting in comparing to (are you ready for this?)… the sound that did not pass via the phonocorrector. OK, now I shell make a long Mahler’s after-Allegro-Maestoso pose…


























One of the many reasons why I do not write audio-reviews because the task to convince the Moronic audio public is too simple. In my personal audio life I need to convince myself – a way much more complicated and much difficult task. If you read my post “Reviewing preamps by imbeciles”:

http://www.romythecat.com/Forums/ShowPost.aspx?PostID=2589

Then you understand my attitude toward to the way how I see preamps. OK, why a phonocorrector shell be different? I use the same demands to RIAA corrector as I have to preamp. So, for a few years I practice the to run the inverted RIAA curve to phonostage and evaluate how the anti-RIAA-phonocorrector tandem competes with sound to the original source that I use to feed the anti-RIAA network. There is always a very specific differences but if you trained to do it and well understand the permanent limitations of your anti-RIAA network then you can say a LOT about the sound of a tested phonocorrector.

So, since end up the “End of Life Phonostage” I spent some time to listen it after the anti-RIAA. I always burn in phonostage with anti-RIAA sound as feeding phonostage with straight 3mV not RIAA sound obliterate lower basses for next 3-4 days. So, I am running the following chain:

88/24 files from DAW - Linx16 - Lavry 924 – Placette Active – Melquiades – Macondo (with Dominus Rev B everywhere)

Against the following chain:

88/24 files from DAW - Linx16 - Lavry 924 – Hagerman’s iRIAA (600R in -60dB out) - End of Life Phonostage - Placette Active – Melquiades – Macondo (with Dominus Rev B everywhere but using Proteus between Lavry and Hagerman’s filter)

EAR834PT.jpg

What do you think the difference in sound is? There are some very minute issuers here and there - it would be hard to comment about them to readers who not tuned to those evaluations BUT the shocking reality is that I generally prefer in term of “musicality” and “humanity” the sound that actually passes through the End of Life Phonostage. It acts as “harmonic’ catalyzer” – very pleasant effect indeed. Perhaps it injects some fat second harmonics into sound but it does NOT sound like ONLY that. I do not know what it does but the effect is there and it is very very very very positive. I would also say that the air-caped 834PTF is insultingly transparent in this test. I can only assure that 100% of people out there would listen that sound coming via the anti-RIAA-phonocorrector tandem with no clue that they were listening the RIAA double-inverted sound. So, whoever Paravicini did with his “HD decay-spectrum as a key indicator" looks like works…

Rgs, Romy the happy Cat

EAR834PT.jpg




"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-05-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,130
Joined on 10-12-2006

Post #: 45
Post ID: 7537
Reply to: 7536
More on this, please

My first thought is that anything a component adds or subtracts, it adds or subtracts similarly to/from everything, like putting the same amount of pepper on all food or salting and watering down all soup to taste +/- the same.

But of course you would not stay happy if this were the case...

So, what is it?

Are we talking about the sort of "re-constituting" and noise dampening that the step-up transformer does, or is this some other form of addition/subtraction that turns insipid, poorly-recorded rock and roll records into angelic soul singing?

Most important, how does it do with a variety of LPs?

I think there is a critical difference between making the best of musical content and simply making music.

I have to admit that although I always long for the latter, I am wary, weary and suspicious even of the notion, so I always wind up with my best version of the former.

Best regards,
Paul S

06-05-2008 Post does not mapped to Knowledge Tree
guy sergeant
United Kingdom
Posts 258
Joined on 08-03-2004

Post #: 46
Post ID: 7538
Reply to: 7537
Interesting development!

Perhaps if you build another phono corrector you could play your TT through that, then through the inverse RIAA then through the EoL corrector then the linestage & power amps etc.

Will you be listening to all of your line level sources via the inverse RIAA and EoL corrector from now on?

06-05-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 47
Post ID: 7540
Reply to: 7538
One-Story Jack
In the absent of any counter hypothesis I stick to mine. By introducing a relatively high level of harmonic distortion at the beginning of the amplification chain with "natural" decay structure the result that reaches our ear/brains is most pleasing, at least as long as we are attending to the music and not analyzing the sound with technical ears that register the sin of commission that has been committed ;o)

Although homogenizing to an extent, for record collectors this is a very nice situation since it allows us to tolerate less than perfect pressings and enjoy the performance without undue distraction from the imperfections in the reproduction. For those who are focussed on the technicalities of reproduction rather than musical content it is not acceptable I guess.

12AX7 vs 6DJ8 anyone?


Brian.
06-05-2008 Post does not mapped to Knowledge Tree
Brian Clark
Ongar, UK
Posts 78
Joined on 10-02-2004

Post #: 48
Post ID: 7541
Reply to: 7534
Nature's Bias
 deemon wrote:
Do you mean a battery bias , Brian ? We didn't try it because of 1 V bias voltage - I don't know if the battery with this voltage does exist . I know only 1,5 V and 1,2 V cells ...... maybe using some chemical reactions we can obtain 1 V or little less , but I don't know how to do it ..... Anyhow , if we use a battery in the grid chain - we still need a resistor ( 2 M ) after the coupling capacitor , and we must add 2 contacts of the battery socket and the battery itself . But the fixed bias , as I think , is a more suitable solution in this case - we have the most simply sound chain from the plate of V1 to the grid of V2 , and the short grounded cathode of V2 . I think that it's the best idea ...
Dima


Sorry Dima, missed your posting first time round this morning.
By "contact potential biasing" I meant the technique that Thorsten likes for 2nd stages - no biasing resistor in the cathode circuit but a very large resistor (10MegOhms upward) for the grid return. This exploits the Volta potential between two differing metals (those of grid wire and cathode surface) in a vacuum to produce a constant small biasing voltage sufficient for the relatively low signal level encountered in this position.

OK as long as grid current doesn't flow of course so not suitable for just any old valve under any old conditions.
However I do note that Thorsten didn't employ this technique when modifying the 834P circuit so I guess there must be good reason in this particular application.
I must ask him.

Brian.
06-05-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 49
Post ID: 7543
Reply to: 7536
The signal passing via the 834PTF-Air…

Will I be listening to all my sources via the inverse RIAA?

Well, the question was sarcastic but it has some rational grains.  If the signal passing via the 834PTF-Air does receive some positive attributes despite of the presumed nastiness of the dual-RIAA filtering then can we found some lessons in this fact?

In fact the lesson is not such a major discovery as I would like to convince myself.  Passing the signal via the “starving” 834PTF-Air turned out to be very educational but I head the same effect from other electronics. The Lamm L1 has remarkably similar effect but the Lamm L1 X factor also included the geometrical poisoning of imagine in a very unique way. The 834PTF-Air does not do it. I have now at home one 16-bit DAC that it trying to compete with my Bidat (it is an evolution for a company and I would like to keep the name private). The contested DAC is better then Bidat …but… the Bidat does have that “it”, that second harmonic dirt, that sets all bets off, making sound much more acoustic-like.

So, what the positive deference between the straight run from my a sources and the signal passing via the 834PTF-Air? I bought yesterday the 2007 Live recording of London Symphony with Gergiev conducting Mahler Sixth. An interesting performance, not perfect but very interesting. What could be more full-range then this! For a save of musically I would go for New Philharmonia with my beloved Barbirolli  -  he owns the M6 and this recording is the only M6 that I might listen for pleasure. For sake of lower levels of pleasure the Gergiev would do… Anyhow, I was experimenting with it running the 834PTF-Air in and out of the loop and it is VERY interesting….  I can get the “interesting” difference only via the immediately switching via the Placette’s remote control using the short-term memory. The difference within long- term memory in very complicated subject with this particular case (there are reasons). So, switching from the 834PTF-Air engaged to direct feed wants make you to vomit. I am not kidding! The sound feels like you Earth suddenly lost effect of gravitate and everything collapses. I make a pose,  listen a direct feed and then turn on the feed with anti-RIAA and 834PTF-Air in the signal path. The sound becomes VERY unpleasant very large but fat, chubby and imbalanced. The domination of the second harms oink is practically unbearable for the short-term memory. However, then mind, not actually not mind but senses and feelings begin to recognize an interesting save net – the sound got suddenly attached by with second harmonics but   at the same time got more dynamic (here is where ET2 does its amassing duty). So that enormous size of sound and it’s ability to flow slaw like a value river (slow is big plus in my book) but at the same time compensated with larger dynamics and ability to accelerate across range more rapidly and more “intelligent” make awareness very fast get use to this new Sound and to embarrass it very-very quick. Literally after 10 seconds I experience no discomfort. I do admit that there is some “coloration of harmonic saturation” but I did not detect so far that this coloration interferes with my listing experiences; I might recognize it later on….

Well, concluding, the saga with the ET2+ 834PTF-Air or as I call it the “End of Life" Phonostage turned out to be very educational. I would certainly do not support and would not advocate the idea of “Injection Channel” on the level of electronics  but  those observations of my make me to this about a lot of things. Why not to introduce the necessary but very defined “Injection” by the driver stage of the DSET for instance where it would be possible to introduce  a warmth of a given charnel by using the idea similar to 834P? It would problem imposable in 2-stage power design. There are many other applications…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-06-2008 Post does not mapped to Knowledge Tree
guy sergeant
United Kingdom
Posts 258
Joined on 08-03-2004

Post #: 50
Post ID: 7544
Reply to: 7543
Apologies!
While the question was somewhat facetious there was supposed to be a serious point behind it.  I experience a similar 'effect' with a linestage I sometimes use. It is quite easy to hear what this stage contributes and initially it is too different to take it seriously.  However, the 'conditioning' or 'shaping' this stage applies is very seductive, I do soon hear past its interpretation and it does, particularly with my digital source, make the music seem more involving & (curiously) the power amplifiers seem more powerful. Learning about this effect & trying to identify what exactly has happened to the sound has been very educational.  It goes right against the virtuous principles of what's normally perceived as high fidelity, but asks the question whether, if the resulting sound is an improvement, (ie subjectively more enjoyable) the means used in achieving it are so important. I suppose that depends on what an individual's idea of improvement actually involves.

Active Line stages in particular have often been a puzzle. The output from your DAC ought to be relayed best directly to the input stage of your power amp, yet its not uncommon to hear an attenuator of some kind coupled with a gain stage actually 'improve' things.  
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