Krell Current Audio Signal Transmission C.A.S.T. - Current mode Technology = CMT - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th February 2010, 06:41 PM   #1
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
Default Krell Current Audio Signal Transmission C.A.S.T. - Current mode Technology = CMT

Regarded Krell's very special connection technology I read this:

CAST (Current Audio Signal Transmission) is the name Krell has given to its novel analog connection scheme. In an ordinary audio system, signal is transmitted in the voltage domain and every component and connecting cable operates as a separate entity that interacts with the other system elements in its own peculiar way. Put as simply as possible, CAST takes advantage of Krell's Current Mode Technology (CMT) to transmit signal as current. This has several advantages -- for one thing, it causes the entire chain of CAST components to behave as if they were a single global circuit. Rather than dictating that the preamp's output be low and the power amplifier's impedance be high, which creates a situation where the interconnecting-cable's impedance can affect (even distort) the signal voltage operating the amplifier, CAST transfers current from a high-impedance source to a low-impedance load, minimizing (if not outright eliminating) the cable's effect on signal transmission. And, if you're using a CD player, the signal can be taken straight off the DACs without going through a I-to-V conversion stage. Krell claims CAST is responsible for a 6dB noise reduction alone.

For me it seems like high impedance output stages connected to low impedance input stages in common base resp. common gate - but what about the details?
Who knows more about the basic circuits concerning this connection in current mode?
  Reply With Quote
Old 15th February 2010, 07:20 PM   #2
diyAudio Member
 
Join Date: Oct 2004
Hi Tief,
I open my Krell KPS 25sc and see the board and cabling of the cast ouput.
Rubén
  Reply With Quote
Old 15th February 2010, 07:54 PM   #3
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by tiefbassuebertr View Post
Regarded Krell's very special connection technology I read this:

CAST (Current Audio Signal Transmission) is the name Krell has given to its novel analog connection scheme. In an ordinary audio system, signal is transmitted in the voltage domain and every component and connecting cable operates as a separate entity that interacts with the other system elements in its own peculiar way. Put as simply as possible, CAST takes advantage of Krell's Current Mode Technology (CMT) to transmit signal as current. This has several advantages -- for one thing, it causes the entire chain of CAST components to behave as if they were a single global circuit. Rather than dictating that the preamp's output be low and the power amplifier's impedance be high, which creates a situation where the interconnecting-cable's impedance can affect (even distort) the signal voltage operating the amplifier, CAST transfers current from a high-impedance source to a low-impedance load, minimizing (if not outright eliminating) the cable's effect on signal transmission. And, if you're using a CD player, the signal can be taken straight off the DACs without going through a I-to-V conversion stage. Krell claims CAST is responsible for a 6dB noise reduction alone.

For me it seems like high impedance output stages connected to low impedance input stages in common base resp. common gate - but what about the details?
Who knows more about the basic circuits concerning this connection in current mode?
Standard industrial practice is to have a 4-20mA current loop for instrumentation in very noisy environments with long cable runs.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 15th February 2010, 09:07 PM   #4
knutn is offline knutn  Norway
diyAudio Member
 
Join Date: Mar 2006
Location: Oslo
Many years ago I made what I called my active passive preamp. I moved my symmetrical JFET input transistors to an enclosure of their own (no power supply is needed!) and the connection to the power amp was done by XLR connections. So the result is high impedance drain output and low impedance common base input in a symmetrical manner. As suggested, the idea is not new; I think it was used in early data communication.
Click the image to open in full size.
  Reply With Quote
Old 15th February 2010, 10:37 PM   #5
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Hardly novel - Sony used it in it's first ES series (the 1980's one) with the name ACT, Audio Current Transfer. Essentially a current output with a resistor I-V conversion scheme at the input terminals.
  Reply With Quote
Old 23rd February 2010, 08:58 PM   #6
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
Originally Posted by ilimzn View Post
Hardly novel - Sony used it in it's first ES series (the 1980's one) with the name ACT, Audio Current Transfer. Essentially a current output with a resistor I-V conversion scheme at the input terminals.
That means, Krell did only invented the name for this newly.

But "Current Audio Signal Transmission" (C.A.S.T.) sounds more special in
advertisements than SONY's "Audio Current Transfer", which sounds rather commonly.

Independend of this - thanks to all for the advices.

Is this type of signal transfering in fact recommended ?
I have never check out this.
  Reply With Quote
Old 13th September 2010, 04:16 PM   #7
diyAudio Member
 
Join Date: Dec 2009
Has anyone done a DIY Krell CAST cable ? I need to know the pin configuration, and the type of cable to use (cable characteristics and impedance)

By the way, the connector is made by Lemo (lemo.com)
  Reply With Quote
Old 7th April 2012, 01:12 AM   #8
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
I have a very nice sounding krell cdp, which has among others a cast output which should be the current output of the dacs.
Which would be the best way to design a preamp input stage to take benefit from this?
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
UC3846 current mode control vs. SG3525 with average current mode control mflorin Power Supplies 35 7th June 2014 09:06 AM
Gain Module with Current Transmission Technology audio-gd Solid State 3 16th September 2013 09:34 PM
Krell CMT, what is it? lumanauw Solid State 2 31st May 2007 04:41 PM
How do I turn an high current signal into a line level signal?? sardonx Tubes / Valves 8 27th August 2005 12:16 PM
Current Mode vs Voltage Mode G-Daddy Solid State 11 27th March 2002 07:11 PM


New To Site? Need Help?

All times are GMT. The time now is 01:10 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2