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Headamp Blue Hawaii Special Edition - Page 380

post #5686 of 5700
Quote:
Originally Posted by arnaud View Post
 

Regardless, you seem to have missed to point of the conversation Eric ;)

 

He's off to buy a Krell.

post #5687 of 5700
Krell??
Actually, redesigning a normal speaker or dynamic headphone amp to run electrostatics is a none starter right?
30 volts output needs to be 500 volts, then the bias current supply. Seems like ots not possible.

Better to build a DIY KGSS?
post #5688 of 5700
Sorry, typo, I meant KGST
post #5689 of 5700

Although it would be financially insane to do so, you could take a pair of

krell master reference monoblocks and use them as a really great electrostatic

amplifier. Although not the voltage champ compared to purpose designed

electrostatic amps, they easily do 800+ VPSS. (+/-220V power supplies)

And the fact that that ground is exactly in the middle makes adding

a bias supply trivial.

 

I did try my fpb600 amp which is about 300 VPSS, and it did sound

really nice. Not a lot of volume, but what was there was sweet.

 

Taking a higher voltage high impedance tube amp and using it

to drive a step up transformer is all sorts of wrong. The impedance

of the headphones looking back thru the transformer at high

frequencies is very low and the current is very out of phase.

post #5690 of 5700
Quote:
Originally Posted by kevin gilmore View Post
 

Although it would be financially insane to do so, you could take a pair of

krell master reference monoblocks and use them as a really great electrostatic

amplifier. Although not the voltage champ compared to purpose designed

electrostatic amps, they easily do 800+ VPSS. (+/-220V power supplies)

And the fact that that ground is exactly in the middle makes adding

a bias supply trivial.

 

I did try my fpb600 amp which is about 300 VPSS, and it did sound

really nice. Not a lot of volume, but what was there was sweet.

 

Taking a higher voltage high impedance tube amp and using it

to drive a step up transformer is all sorts of wrong. The impedance

of the headphones looking back thru the transformer at high

frequencies is very low and the current is very out of phase.

 

This may be true with a 1:50 Transformer (Wee Box) but less true with a 1:5 transformer (AudioValve Verto Box), with a Stax Headphone (sensibility 101 dB / 100 Volt RMS) driven by the OTL RKV-II Amp (with internal resistance (output impedance) 0.01 Ohm, and output voltage : 80 to 100 Volt RMS)

 

show you the excellent transmission properties of the VERTO used on a STAX headphone connected to the output of the RKV Mark 2 as driver.

show you a triangle signal by 10 kHz  

 

Link : http://www.audiovalve.info/rkv/audiovalve%20rkv%20mark2.php


Edited by eric65 - Yesterday at 8:17 am
post #5691 of 5700
Quote:
Originally Posted by eric65 View Post
 

 

This may be true with a 1:50 Transformer (Wee Box) but less true with a 1:5 transformer (AudioValve Verto Box), with a Stax Headphone (sensibility 101 dB / 100 Volt RMS) driven by the OTL RKV-II Amp (with internal resistance (output impedance) 0.01 Ohm, and output voltage : 80 to 100 Volt RMS)

 

I'm sorry, but this is absolutely impossible. Not even a 6c33 can possibly approach .01 ohm output impedance.

No need to argue any further, you have your opinion, and I have mine.

post #5692 of 5700
Quote:
Originally Posted by kevin gilmore View Post
 

 

I'm sorry, but this is absolutely impossible. Not even a 6c33 can possibly approach .01 ohm output impedance.

No need to argue any further, you have your opinion, and I have mine.

 

SPECS: OTL mode: (RKV-III amp, OTL mode)

  • power output:  5,8 watt - 220 ohm load - ( 1% THD )
  • max. output voltage 100 VAC / 2kohms load
  • bandwide: 10 - 150.000 hz ( 100 ohms )
  • Ri: 0.01 ohm
  • THD:  configure - LM 351 - 3V - 1 kHz
  •      100 ohm load 0,014%
  • THD:  configure - LM 351 - 3V - 10 kHz
  •      100 ohm load 0,014%

 

link : http://www.audiovalve.info/rkv3/audiovalve%20rkv%20mark3.php

post #5693 of 5700
Quote:
Originally Posted by eric65 View Post

SPECS: OTL mode: (RKV-III amp, OTL mode)
  • power output:  5,8 watt - 220 ohm load - ( 1% THD )
  • max. output voltage 100 VAC / 2kohms load
  • bandwide: 10 - 150.000 hz ( 100 ohms )
  • Ri: 0.01 ohm
  • THD:  configure - LM 351 - 3V - 1 kHz
  •      100 ohm load 0,014%
  • THD:  configure - LM 351 - 3V - 10 kHz
  •      100 ohm load 0,014%

link : http://www.audiovalve.info/rkv3/audiovalve%20rkv%20mark3.php

You seem to be pushing audiovalve gear eric65, are you on commission ?
post #5694 of 5700
Quote:
Originally Posted by David1961 View Post


You seem to be pushing audiovalve gear eric65, are you on commission ?
No, I'm independent.
Just sharing idea and experience with members of the forum (Head-Fi and HCFR)
post #5695 of 5700

so lets look at the schematic for a few minutes...

http://www.jogis-roehrenbude.de/Verstaerker/PCL805-KH-Amp/Schaltung.jpg

and of course the new one is balanced so its going to have twice

the output impedance.

 

See that output capacitor, C26...  its outside the feedback loop.

Now the lowest impedance electrolytic I have been able to find

(and you probably not want to listen to it) is 130 milliohms.

So that Ri is clearly immediately shot in OTL mode, which is the mode

you are supposed to use when you drive the electrostatic transformer.

 

but wait, there is significantly more.

http://frank.pocnet.net/sheets/010/p/PCL85.pdf

The resistance of the plate is roughly 10K

So even with all the feedback in the world maybe if you are lucky

you will get the output section impedance down to 500 ohms.

My best guess without actually building and measuring it is

closer to 2500 ohms.

 

now you are going to drive a 1:5 transformer into 120pf  with that.

reflected input impedance at 20khz roughly 2600 ohms at 90 degrees

phase.

 

plus the extra power for the self bias...

 

There are better ways.


Edited by kevin gilmore - Yesterday at 12:00 pm
post #5696 of 5700

The discussion becomes very technical, and unlike yourself and Mr. Becker (rkv father) of the AudioValve company, I am not a specialist.


I however hit a word on the HCFR Stax thread (followed by Mr. Becker) concerning your critics about the PCL805 tubes for audio application, in particular for the electrostatic headphones (via the 1:5 of the Verto transformers).http://www.homecinema-fr.com/forum/post178195460.html#p178195460
 Maybe Mr. Becker will be able to give us here on this thread (or HCFR) his vision of things, and its practical application in its draft Verto.

 

Verto box which by the way, coupled with the RKV amp, operates both electrostatic headphones (output number 3: Stax), Orthodynamic headphones low impedance (output number 2 : 32 Ohm) and headphones or speakers high performance 8 Ohm impedance (output number 1 : 8 Ohm).

 

(NB : BHSE amp (a very good electrostatic amplifier) has only one output (the one for Stax Headphone)).


Edited by eric65 - Yesterday at 1:51 pm
post #5697 of 5700
There's a saying, Jack of all trades, master of none.
post #5698 of 5700
Quote:
Originally Posted by David1961 View Post

There's a saying, Jack of all trades, master of none.

More down to Earth, there's also a question of price (of money):
Make your choice...

 

see the link (in french) http://www.homecinema-fr.com/forum/post178189887.html#p178189887

 

 

PS : Sorry, you can use your favorite translator

post #5699 of 5700

I tried this many years ago, and nothing would prevent you from doing

the same thing now. A srd7 or wee wired in reverse being driven from

a BHSE (or really any other electrostatic amp) would generate a very

low output impedance with more than sufficient power to drive any

dynamic headphone you want to drive, he6 included.

 

With the appropriate transformer into 50 ohms on a BHSE you should

be able to do about 8.5 watts pure class A. With slew rates far in excess

of virtually all dynamic amps including futterman clones with a solid state

front end and massive amounts of feedback.

 

As far as price, I really don't care about price, I care about quality.

I own BH,BHSE,T2,ES1,ES2,Megatron,KGST, KGDT,GES and that is just the tube

electrostatic amps


Edited by kevin gilmore - Yesterday at 4:24 pm
post #5700 of 5700
Quote:
Originally Posted by eric65 View Post
 
Quote:
Originally Posted by David1961 View Post

There's a saying, Jack of all trades, master of none.

More down to Earth, there's also a question of price (of money):
Make your choice...

 

 

I already have the BHSE which is what this thread is mainly about.

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