Silver RKV MkII (first pic)
Feb 23, 2004 at 1:00 AM Post #31 of 56
Link to the silver version doesn't work
frown.gif
 
Feb 23, 2004 at 11:54 AM Post #32 of 56
Quote:

Originally posted by Sugano-san
No, it's not. It's a ladder type stepped attenuator.


thanks sugano san,

normally, a 4 deck stepped pot is a balanced pot. it seems this is a custom made pot then.
 
Feb 23, 2004 at 11:56 AM Post #33 of 56
Quote:

Originally posted by Sugano-san
No, it's not. It's a ladder type stepped attenuator.


sugano san;

what is so special about your ladder type stepped pot? how does it differ from for instance the dact pots? the dact only needs 2 decks for stereo, the 4 decks are for balanced pots. i am curious if these are even better.
 
Feb 23, 2004 at 12:07 PM Post #34 of 56
Quote:

Originally posted by tourmaline
it seems this is a custom made pot then.


No, it's not. I know of three different technical approaches to stepped attenuators: series, shunt and ladder. Ladder is the best. I am not an engineer, so I simply copied the following explanatory text from the Goldpoint Comparison Page:

"In a ladder type stepped attenuator, the rotary switch is used to select an input-to-output resistor and an output-to-ground resistor, forming a separate voltage divider for each switch position.

The total series resistance for each two resistor set in a ladder attenuator is equal, so the signal source sees a non varying impedance.

Having only two resistors active for any chosen switch position results in the lowest possible resistor noise, and makes it easy to achieve matched channel-to-channel signal levels.

Goldpoint Ladders are the best 24-position ladder attenuators available anywhere."



advantages + Only two resistors active per switch position.
+ Very precise signal level tracking.
+ Non varying input impedance.
+ Low resistor noise.


Click on the link provided above to find out more details. I trust this is helpful. I am not familiar with DACT products.
 
Feb 23, 2004 at 1:18 PM Post #35 of 56
Quote:

Originally posted by tourmaline
what is so special about your ladder type stepped pot?


I found this definition in the Tube Audio Glossary. It may be helpful.
 
Feb 23, 2004 at 3:35 PM Post #37 of 56
Tourmaline, see www.goldpt.com for their stepped attenuators. One difference between the Goldpoint and the DACT is that the DACT uses surface mount resistors while the Goldpoint uses Dale/Vishay or Roderstein resistors.
 
Feb 23, 2004 at 4:02 PM Post #38 of 56
Interesting link Canman.

IMO the 'usual' serie attenuator are better 'cause of only one contact in the signal path.
Ladder model allow more precise attenuation from step to step ( you can play with 2 resistors value) but the signal path is a 'little' more complicated with 2 switch contact.
 
Feb 23, 2004 at 5:30 PM Post #39 of 56
IMHO, one more contact switch will harm the signal far less than going through 8 or 10 resistors, how good they are.

And ladder and series can be configured to have exactly the same steps. Actually, you don't "play" with two values in ladder type. The values are linked in a simple relation in which their sum must be constant to preserve a constant input impedance.
 
Feb 23, 2004 at 6:34 PM Post #40 of 56
Quote:

Originally posted by 00940
IMHO, one more contact switch will harm the signal far less than going through 8 or 10 resistors, how good they are.


Hmmm...that leaves room to debate i think
wink.gif


Whatever you choose, the difference ( if there's one ) must be very small.
 
Feb 23, 2004 at 6:58 PM Post #42 of 56
Quote:

Originally posted by 00940
Sugano-san I noticed the caps were changed in your RKV. Which brand is used now ?


Hi Ben, I already tried to e-mail you, but "colorado" appears to be disabled...

Anyway, the caps have not been changed (not to my knowledge anyway, and certainly not by me), and I have no idea what the brand is...

--Gioacchino


edit/P.S.: The plastic foil was removed from these caps, that's probably why they look different.
 
Feb 23, 2004 at 7:08 PM Post #43 of 56
Quote:

Originally posted by Sugano-san
Hi Ben, I already tried to e-mail you, but "colorado" appears to be disabled...


Oh, you're right, i forgot that
redface.gif
This account no longer exists.

Strange, from your pics, the caps looked slightly narrower. Anyway, if I were you, i'd consider to have the output caps changed. BC caps are not exactly the best you can find.
 
Feb 23, 2004 at 7:13 PM Post #44 of 56
Quote:

Originally posted by 00940
Anyway, if I were you, i'd consider to have the output caps changed. BC caps are not exactly the best you can find.


I have no idea what BC caps are, but I will certainly consult you when the time has come. Thanks a lot for your observations!
 
Feb 23, 2004 at 8:09 PM Post #45 of 56
The BC series are made by Philips. They're "good" quality electrolytic. Pretty good but not outstanding. They are 4 of them in a RKV : two for the power supply and two as output caps, on the signal to block DC. They are those big blue caps (the stripped ones in yours).

I'm not a specialist, I just spent some times hunting similar caps for my amp. I settled down for Audyn MKP 220uF, but they're physically too big to fit into a commercial rkv. There are tons of persons far more qualified than I am here, like Carlo, Jeffreyj and a lot of others. There is a post about this quest for good output caps here : http://www5.head-fi.org/forums/showt...=impedance+rkv and another one here : http://diyaudio.com/forums/showthrea...135&highlight= .

I was going to use a pair of Rifa PEH169 220uF ( http://www5.head-fi.org/forums/showt...ghlight=peh169 ) but I was lucky and scored a pair of those big audyn on ebay.de. If you're interested in these rifa, I'm keeping them on a shelf. You can have them at the price I paid them.
 
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