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Coupling Caps for a 300B SET

69.17.141.46
Posted on January 2, 2020 at 09:00:50
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 Any suggestions for replacement caps for this type of amps? Good reliable ones that are not too expensive. I like neutral sound or close it. Less than $100 each is what I can afford.
Thanks I'm advance

 

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Value? (NT), posted on January 2, 2020 at 11:16:02
jeffreybehr
Audiophile

Posts: 5707
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since: December 13, 2004
 .

 

Which 300B SET amp? nt, posted on January 2, 2020 at 12:09:37
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 04:14:38
Stuben
Audiophile

Posts: 669
Location: Guber Ohio
Joined: December 30, 2005
 For bang for the buck, Russian PIO have been my go to for a few years. The price is going up.

Stuben

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 05:46:43
RPMac
Audiophile

Posts: 377
Location: So. Mississippi
Joined: January 3, 2005
 FT-3 Teflon

 

RE: Value? (NT), posted on January 3, 2020 at 08:15:22
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 Value is 1uF 450V minimal.

 

RE: Which 300B SET amp? nt, posted on January 3, 2020 at 08:17:56
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 Emotive Audio Caeli. I'm using a KR300BXLS ....rectifier is 274B

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 10:54:54
pcuser
Audiophile

Posts: 28
Location: Sofia
Joined: February 9, 2008
 Miflex KPCU01-1U/600
Jensen Copper Foil, Paper in Oil or Jupiter Copper Foil Paper & Wax Capacitors are better, but the price...
1uF is to large for Coupling Cap?
FT-3 is worse than Miflex for me.

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 11:39:10
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 What is in there now?

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 14:25:40
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 You're the third person who mentioned that 1Uf is too big. I'm not an expert but I'm suspecting you correct.

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 14:27:08
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 Whats in there now? Solen Silver teflon. 1uF 700V.

 

cathode follower, posted on January 3, 2020 at 14:28:47
RayP
Audiophile

Posts: 727
Location: Maryland
Joined: June 30, 2005
 I see from the manufacturer's website that the 300B is driven directly by a cathode follower so presumably the capacitor is between the input tube and the cathode follower. Do you have more details about the cathode follower? Perhaps you can use a smaller cap than 1 uf.

ray

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 14:31:11
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 Do you know the resistance value of the grid resistor on the cathode follower stage?

That is what determines the needed value of the coupling cap.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Maybe you could post some pictures of the bottom of the amp, posted on January 3, 2020 at 14:33:12
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Maybe you could post some pictures of the bottom of the amp, posted on January 3, 2020 at 15:21:32
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 My technician has the amp right now and he thinks that there are other folks that work on it. There are a few things that were done on it that could be better.

 

RE: Maybe you could post some pictures of the bottom of the amp, posted on January 3, 2020 at 15:29:37
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
 Hope your tech actually knows what he is looking at. I've seen a few Emotive amps, and the build is usually a bit unusual.



Dan Santoni

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 15:59:27
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 What don't you like about them? I used Rel Teflon's in my Sira preamp.

 

RE: Maybe you could post some pictures of the bottom of the amp, posted on January 3, 2020 at 16:09:16
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 I find it hard to believe. Did you ask Fred?

 

RE: Coupling Caps for a 300B SET, posted on January 3, 2020 at 18:39:31
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 There's nothing about the amp that I don't like. I just want to try different caps, different flavour.

 

RE: Coupling Caps for a 300B SET, posted on January 4, 2020 at 07:36:21
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Unless you are going to try VCap CuTFT or Jupiter Cooper/Wax, I wouldn't bother.

 

RE: Coupling Caps for a 300B SET, posted on January 5, 2020 at 09:02:44
mg16
Audiophile

Posts: 1022
Joined: October 18, 2001
 Very happy with Audyn plus ,from Hifi Collective, caps in my 300B monos.
mg16

 

Try 0.47uF Jupiter Copper or VCap TFTF sale, posted on January 6, 2020 at 17:35:29
Jon L
Audiophile

Posts: 6062
Joined: April 6, 2000
 "Unless you are going to try VCap CuTFT or Jupiter Cooper/Wax, I wouldn't bother."

I fully agree with this assessment.
I also do not believe 1uF coupling caps are necessary and would look at the much cheaper 0.47uF caps. Jupiter copper foil/wax 0.47uF/600V runs $99, under your budget, and VH Audio is having 40% closeout on the TFTF teflon caps, which I personally would pick for 300B SET tube amps over CuTF...

 

RE: Try 0.47uF Jupiter Copper or VCap TFTF sale, posted on January 7, 2020 at 06:58:06
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since: September 9, 2000
 Yes on the Teflon's in a 300B. I have the CuTFT in my 801A. I had REL Teflon in my old 845.

 

RE: Try 0.47uF Jupiter Copper or VCap TFTF sale, posted on January 7, 2020 at 07:27:09
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 From a 1uF to .47uf ..... what sonic difference should I expect? Will I have any issues?

 

RE: Coupling Caps for a 300B SET, posted on January 7, 2020 at 16:08:17
GTCharlie
Audiophile

Posts: 983
Location: Philippines
Joined: December 9, 2004
 Assume say 470k.... a 0.22uf would do very well

 

RE: Coupling Caps for a 300B SET, posted on January 8, 2020 at 06:07:05
audiophilewannabe
Audiophile

Posts: 640
Location: toronto
Joined: July 19, 2004
 470k? Or 470Vdc

 

470,000 ohms (nt), posted on January 8, 2020 at 06:27:21
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007

 

RE: Coupling Caps for a 300B SET, posted on January 9, 2020 at 23:40:22
GTCharlie
Audiophile

Posts: 983
Location: Philippines
Joined: December 9, 2004
 That's in answer to an earlier question. But just an assumption.

Thats the resistor from thr grid of your driver tube, to ground

 

RE: Try 0.47uF Jupiter Copper or VCap TFTF sale, posted on January 11, 2020 at 17:53:16
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 You have to know the value of the grid resistor for the next stage to determine if the .47uf cap will pass all the bass frequencies vs. the 1uf cap.

Did you ever look at the unit to try to determine the value of those resistors?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Coupling Caps for a 300B SET, posted on February 18, 2020 at 19:04:37
Retsel
Audiophile

Posts: 1238
Joined: April 17, 2000
 If you want to save money, you could parallel your current coupling cap with a TFT cap which is 10% of the value of the current coupling cap. This is not as good as replacing the entire capacitor, but it will get you a good part of the way there.

I have heard that grid chokes make a large difference, although I have not tried this myself. You may find it more impactful to experiment with grid chokes, although their design and use is complicated.

Retsel

 

Yep - Russian teflons. FT-2, FT-3, K72,, posted on March 21, 2020 at 14:04:14
andy evans
Audiophile

Posts: 4378
Joined: October 20, 2000
 I bought a stack of these Russian teflons back in the day and I've never used anything else. FT-2 are useful to parallel up since they're the smallest. Very clean sound.

Better than any polypropylenes I've used. I have very limited experience of boutique paper in oils, though the vintage ones I tried were nowhere near as good. Polystyrenes were a bit more light sounding and I prefer teflon to silver mica, good though that is.

 

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