Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: tttubes on March 31, 2010, 08:33:52 AM

Title: Eros and a TVC
Post by: tttubes on March 31, 2010, 08:33:52 AM
Ok I've ordered a Eros and I guess I should have asked this first will the Eros be able to drive a Silk TVC trasformers I will be using mm cartridges with an out put of 2mv-4mv.

Thanks Jim 
Title: Re: Eros and a TVC
Post by: Doc B. on March 31, 2010, 09:24:20 AM
The cartridge output level will be fine for the Eros. Silk claim an inductance for the TVC that is equivalent to a 50K attenuator (450H). If that is true it should work well with Eros.
Title: Re: Eros and a TVC
Post by: tttubes on March 31, 2010, 09:35:24 AM
Thanks also I have a pair of audio note copper foil paper in oil .47mf caps could I replace the 1mf solens with them.

Thanks Jim
Title: Re: Eros and a TVC
Post by: Paul Birkeland on March 31, 2010, 10:38:31 AM
Yes, .47 is an acceptable value for what you're up to.  Also the 47k 2w and 75k .5w plate load resistors are good candidates for an upgrade.

-PB
Title: Re: Eros and a TVC
Post by: tttubes on March 31, 2010, 10:53:52 AM
Quote from: Caucasian Blackplate on March 31, 2010, 10:38:31 AM
Yes, .47 is an acceptable value for what you're up to.  Also the 47k 2w and 75k .5w plate load resistors are good candidates for an upgrade.

-PB

What would be good ones to get and how many.

Thanks Jim
Title: Re: Eros and a TVC
Post by: Grainger49 on April 05, 2010, 02:45:52 AM
Quote from: Caucasian Blackplate on March 31, 2010, 10:38:31 AM
  .  .  .   Also the 47k 2w and 75k .5w plate load resistors are good candidates for an upgrade.

-PB

Paul,

I started looking at the usual places for high tolerance resistors with these wattage ratings and found only one that would fit the 47k 2W rating.  Parts ConneXion has an Audio Note Tantalum for $14.  But I'm not sure the specs that are most important in this application.  Are we looking for linearity across temperature?  

Thanks,
Title: Re: Eros and a TVC
Post by: Paul Birkeland on April 05, 2010, 01:31:12 PM
Yeah, you can get in a lot of trouble blowing dough on four resistors, lol.  I might try these two sets in the Eros:

http://www.partsconnexion.com/resistors_amtrans_amrg_two_watt.html (http://www.partsconnexion.com/resistors_amtrans_amrg_two_watt.html)

(47k 2w)

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SM102J-75K-ND (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SM102J-75K-ND)

or

http://www.partsconnexion.com/product11679.html (http://www.partsconnexion.com/product11679.html)
http://www.partsconnexion.com/product11686.html (http://www.partsconnexion.com/product11686.html)
Title: Re: Eros and a TVC
Post by: grufti on April 05, 2010, 05:42:29 PM
Quote from: Caucasian Blackplate on April 05, 2010, 01:31:12 PM
Yeah, you can get in a lot of trouble blowing dough on four resistors, lol.  I might try these two sets in the Eros:

http://www.mouser.com/ProductDetail/IRC/GS3T0-47K-5/?qs=xiu8sNHfdiUb4WlW8fueUQ%3d%3d (http://www.mouser.com/ProductDetail/IRC/GS3T0-47K-5/?qs=xiu8sNHfdiUb4WlW8fueUQ%3d%3d)
http://www.mouser.com/ProductDetail/IRC/GS3T0-200K-1TR/?qs=dzepuz1rY1qPlPRAzkNmPQ%3d%3d (http://www.mouser.com/ProductDetail/IRC/GS3T0-200K-1TR/?qs=dzepuz1rY1qPlPRAzkNmPQ%3d%3d)

or

http://www.partsconnexion.com/product11679.html (http://www.partsconnexion.com/product11679.html)
http://www.partsconnexion.com/product11701.html (http://www.partsconnexion.com/product11701.html)


I'm lost when it comes to the 200K resistors. I don't recall seeing those in the Eros schematic/parts list. Did those values change at some point or should those two url's point to 75K resistors instead?
Title: Re: Eros and a TVC
Post by: Paul Birkeland on April 05, 2010, 06:39:45 PM
Sorry, I am thinking of another circuit that uses the 200k resistors.  I will edit the post above.
-Paul
Title: Re: Eros and a TVC
Post by: ssssly on April 05, 2010, 11:39:17 PM
FYI the Audio Note tantalums are magnetic.

Shinkoh tantalum are not.

Neither are Takman. And they are great sounding resistors as well. 
Title: Re: Eros and a TVC
Post by: Grainger49 on April 06, 2010, 02:03:44 AM
PB,

Like the carbon composition resistor is the choice for a grid/plate stopper, is there a better selection for the plate load resistors?  I see that all your suggestions are carbon film.  The stock 47k ohm resistor is a big 2W MF and the other is a 75k CF.  Both must passing some current!  Is carbon film better for this application than metal film or tantalum.
Title: Re: Eros and a TVC
Post by: Paul Joppa on April 06, 2010, 08:47:30 AM
For load resistors drawing DC current, the best are metal. Probably bulk metal film and (non-inductive) wirewound are the best, with quality metal film close behind. The stock 75K should be metal film, not carbon film - that's likely a misprint in the manual.
Title: Re: Eros and a TVC
Post by: Paul Birkeland on April 06, 2010, 09:04:21 AM
Quote from: Paul Joppa on April 06, 2010, 08:47:30 AM
For load resistors drawing DC current, the best are metal. Probably bulk metal film and (non-inductive) wirewound are the best, with quality metal film close behind.

I have tried metal film and carbon film in the Eros circuit with equal results.  Heck, the carbon film plate loads in the Seduction are even pretty quiet.  

The Digikey 75k thick film looks like an interesting option...
Title: Re: Eros and a TVC
Post by: Grainger49 on April 06, 2010, 02:41:24 PM
Thank you both!