Fidelity Research FR-64 vs. FR-54

bdp, Inside the chassis of each of my Beveridge amplifiers is the inscription, done in magic marker: "RM 1979".  Knowing that Modjeski collaborated with Harold Beveridge back then, I have always assumed that he is "RM".  With the help of an EE who owns a pair of Model 2 speakers, I/we have made quite a few improvements to the circuit, but there is only so much you can do, because the input stage is amazingly complex to begin with and for good reasons.  He usually sends me long and detailed email instructions, and I print them out to have them at hand before doing anything new or trouble-shooting.  I zapped my finger-tip once with 1600V; you don't forget that experience.  When the speaker is fully assembled, the panels sit directly on top of the amplifier providing a direct connection between the two. The amplifier section effectively is the base of the speaker, for each channel. No loose speaker wires allowed.  I bought a copy of the schematic from RM, a few years ago when I first acquired the Bevs.

There's at least one company (in Europe) that markets a ESL direct-drive amplifier which they claim can drive the Sound Labs, which is no mean feat, since the SLs require at least 5kV on each stator (and no one outside of the SL factory really knows exactly what the voltage needs to be).  Ralph Karsten says he can make one, too. I am tempted. Maybe in my idle retirement years I will try it.

Dear @thekong :  """  Makes no sense to me that you ask for some tests in my audio system when I have to prove you or any one else nothing at all.  """

I told you ( and every one. ) those because what I'm doing in this thread was and is only to share my first hand experiences, not to convince any one of something.

I repeat, only sharing my experiences as always did and do.

Regards and enjoy the music,
R.

Dear @lewm : """  you have never heard my Sound Lab speakers or any Sound Lab speakers that have been dramatically altered as have mine... """

Sorry but that is not the main subject through my posts here but only a part of. I think you are missing the whole and main subject.

Anyway, you already know ( because I posted over the forum more than 3-4 times. ) that the only ESL speakers I could live with could be the Soundlabs. As you know a close friend of mine owns the top of the line here in México city an he received as 3 months ago  his originals speakers that he send it for an up-date and he made it some tweacks on it but I'm not sure exactly what he did it and is not this the main subject.
I explain all those for you be aware that I know very well Soundlabs as my friends's modified ones. No, not exactly the same you own but it's not so important as you think.

There are several critical issues that I touched in my posts in this thread and the more important relationed with your main system are:

- first that the analog and/or digital signal pass through several tubes when one tube destroy the audio signal integrity in higher way than a bipolar transitor several ones/tubes is something catastrofic for say the least.

- that main system have not an adequated system bass management and with out it any single system is totally incomplete. Home audio MUSIC belongs two both frequency extremes and very special on that accurate " bass management ".

OTL designs can't help becaus etubes are there. All your ESL modifications can't honor MUSIC till those tubes disappears from the audio signal and till you have that accurate/adequate system bass management.

There are other issues but is useless to continue speaking about till things changes in those both critical subjects that are indisputable/incontrovertible.

Regards and enjoy the music,
R.

Makes no sense to me that you ask for some tests in my audio system when I have to prove you or any one else nothing at all.

Dear Raul, of course you have no obligation to prove to me, or anyone else, it is your system after all! Only that you always claimed to be willing to learn that I thought you would be interested in a simple test, which would take you less time to carry out than writing the response, to prove to YOURSELF whether airborne feedback was causing any problem in your system.

Well, after all those distortion talks, I suppose it feels better living in the comfort of the pipe dream believing all is well in your system, than to venture into the potential horror of finding out airborne feedback is indeed causing distortions. The true horror was, of course, the claimed highly trained ears couldn’t even detect that!

""" I suppose if you play the Telarc 1812 at 109db peak, you probably could feel the pressure on your chest. """

that stament you made it confirm you understand it because in my today enviroment I don’t feel the pressure in my chest ! ! !

That is interesting, playing Telarc 1812 at 109db peak (yes, those cannon shots) without feeling the pressure on your chest! That really gives me a better picture regarding the performance of your system, thank you! Yes, you are right, I don’t have that in my system, I can’t imagine that, but then, I also don’t want that !

Interesting enough, you posted the following in another thread:

Dear @enginedr1960: Yes, always near field live MUSIC is the perfect REFERENCE for audiophiles…..

https://forum.audiogon.com/discussions/my-personal-experience-with-direct-drive-versus-belt-drive

Do you really believe your chest wouldn’t feel the pressure if you were standing close to those live cannon shorts during the recording of the Telarc 1812?

If you think the talk of airborne feedback is nonsense, then please take a look at what a true expert, Mr J Carr, who you like to quote to support your position on the FR64S, had to say (emphasis by capitalization by me) :

BTW, I wouldn’t recommend combining the phono preamp together with the power amp. THE SOUND OF THE TURNTABLE IS TOO MUCH AFFECTED BY VIBRATIONS TRANSMITTED THROUGH THE AIR AND GROUND. FOR TOP PERFORMANCE THE TURNTABLE SHOULD BE IN A SEPARATE ROOM/CLOSET ISOLATED FROM THE VIBRATIONS AND AIR PRESSURE FROM THE LOUDSPEAKERS. If you were to go with a combination phono/preamp/power amp together with the turntable in an isolated room, the speaker cables would likely need to be v-e-r-y long.

https://forum.audiogon.com/discussions/best-phono-preamps

Of course, if you are happy with the current performance of your system, then by all means enjoy it!

Best regards,

Dear @thekong : Look, I never said that air borne does not produce vibrations/distortions. In the other side, I already did it that test.

Now, it's precisely that good or bad system's bass management and the way is handle for who determines how those bass waves arrives to your seat position.

The bass waves of fundamental notes in the 1812 cannon shots  ( 8hz-16 hz. ) through a home system can't impact your chest because are not " builded, yet. . Are to big waves ( a little different in an open enviroment as how those shots were recorded. I have not this live experience, so I can't tell you about. ). These big waves normally came from the floor up and depending of that system/room handling is how you will feel it. If you can feel it in your chest then what you are feeling could be some of the overtones distorted by that bad system/room management. Those overtones came developed from the fundamental notes. Maybe your system can't even ( electronics. ) reproduce those frequencies or your speakers and that's why you can't live today my experiences.

I don't want to go deeper in this important regards till you can mimic ( more or less. ) my system/room experiences I shared here.

Opinions has no real value with out first hand experiences on what other people shares.
You, me and every one need to have facts on hand not theories or just opinions on what we think about. Where are those facts?: FIRST HAND EXPERIENCES IN SIMILAR CONDITIONS.

Regards and enjoy the MUSIC not DISTORTIONS,
R.