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KT-600 with film cap power supply suggestions

107.2.64.57
Posted on December 18, 2014 at 08:08:50
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002



With all this talk of tube preamps and film power supplies, it is time to get my Lafayette KT-600 power supply updated.

I'm looking for suggestions on film caps for C1 and C2. These 475v can caps are currently
C1a 30uF, C1b 20uF, C1c 40uF, C2a-C2c 40uF and C2d 25 uF/25v.

I've updated the selenium bridge but now want to get B+ updated.

My uncle built this in 1959. I think it cost him $79.

I thought either Eli or Mikey had a mouser link to film caps but I couldn't find it. Any help would be grateful.

Thanks

looking for some jazz and a little libations - js

 

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RE: KT-600 with film cap power supply suggestions, posted on December 18, 2014 at 08:57:58
Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014
 Perhaps these where the ones you were looking for.


WIMA DC Link
http://ca.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=175171925

And the less expensive Panasonic DC Link.
http://ca.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=142971265

Cheers.

△This message will self destruct in 10 seconds△

 

RE: KT-600 with film cap power supply suggestions, posted on December 18, 2014 at 10:20:52
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 First things 1st. Get the wretched 1/2 wave rectifier out of there! If a quad of Cree C3D02060F Schottkys will mechanically fit, look no further. If space is a problem, use 4X UF4007s. Either way, full wave bridge rectify the B+.

Put a CL-130 inrush current limiter between the bridge and the PSU filter. Use a 100 muF./400 WVDC cap. as C1A. A top notch 'lytic is fine here. Film caps. after the choke will give you maximum bang for the buck. It looks like C2B does not directly feed any tube plates. So, another GOOD 'lytic will be fine. Where a PSU cap. feeds 1 or more plates, use a metalized polypropylene film part of adequate WVDC, such as Solen.

BTW, try for 105o C. rated parts, when buying capacitors.

edit: grammar


Eli D.

 

RE: KT-600 with film cap power supply suggestions, posted on December 18, 2014 at 21:07:54
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002
 Thanks Garg0yle and Eli.

I dug through my parts box and found 8 UF4007, a few CL-40 and some Sprague Atoms electrolytic caps still in mouser bags.

C2b does feed the plates for the line stage before the tone stack. My schematic is from Sams and the link below might be the original Lafayette. C1B might be good for a electrolytic.

BTW, I did find the McIntosh Amplifier Clinic graph for the pre dated 8-14-65, original Lafayette receipt dated March 30, 1960 at a cost of 79.50 and a few other gems.

Thanks again.

looking for some jazz and a little libations - js

 

Ive been in South Fla visiting my daughter and sister., posted on December 19, 2014 at 21:28:41
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 I got here on the 16th and I ended up in the emergency room at Mt Sinai on the 17th with a 102.6 temp due to a respiratory infection and an infected kidney stone. I have the infectious bug that has been all over the news…This is why I haven't answered.
Anyway,the KT600 is a hell of a preamp and I would put in a 120uf low ESR 105 degree cap that Eli suggested. You can also try a 50@500v panasonic poly if you want along with a Schottky diode.You have room in there.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Ive been in South Fla visiting my daughter and sister., posted on December 20, 2014 at 05:30:28
geoff
Audiophile

Posts: 3499
Joined: April 5, 2000
Contributor
  Since: September 10, 2003
 Man, what a year you've had, health-wise! It's fortunate that you are with family. Take it easy.

 

RE: KT-600 with film cap power supply suggestions, posted on December 20, 2014 at 08:36:56
rickl
Audiophile

Posts: 583
Location: Twin Cities
Joined: February 7, 2002



Wow Mike. This is not that important. Please get well.

To help you get better, here is the McIntosh clinic scan for the pre.
looking for some jazz and a little libations - js

 

AA Man of the Year..., posted on December 20, 2014 at 08:40:37
onemug
Audiophile

Posts: 1276
Location: So. California
Joined: April 19, 2003
 You are definitely in the running. Get well soon.

 

Thanks onemug and Geoff., posted on December 20, 2014 at 17:08:15
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 I have certainly had a very tumultuous two years because I actually passed a stone back in March of this year. My daughter lives two hours from my sister and you are right,family makes all t5he difference and my mom is down here visiting as well as she stays down here for four months as well.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Ive been in South Fla visiting my daughter and sister., posted on December 22, 2014 at 09:07:23
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 Wow Mike, that is quite an ordeal. I hope you are feeling better soon!

Dave

 

Eli, I keep reading divergent views for the film cap..., posted on December 22, 2014 at 14:45:28
gkargreen
Audiophile

Posts: 1562
Location: DC
Joined: February 5, 2005
 position if using only 1 (or 2). I have read that the film cap should be the first (input) cap, someone else the last cap in the filter, and you are saying somewhere in the middle?

 

RE: Eli, I keep reading divergent views for the film cap..., posted on December 22, 2014 at 16:34:21
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Let me clarify
I stress the film cap in the first stage when you are coming off a rectifier tube. If you are coming off sand diodes,you want a low ESR high ripple current electrolytic such has a 105 degree Panasonic or Nichicon or CDE. You can use a film cap but keep in mind that you usually need a higher value capacitance and that can take up some real-estate in the amp or preamp. Anyway,you can use the film caps downstream even if you use an electrolytic.

"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Eli, I keep reading divergent views for the film cap..., posted on December 22, 2014 at 17:10:19
gkargreen
Audiophile

Posts: 1562
Location: DC
Joined: February 5, 2005
 thanks, Michael, so if I am using a tube rectifier, first cap should be film/foil, whereas if it is a sand rectifier, use a 'lytic cap, correct?

 

RE: Eli, I keep reading divergent views for the film cap..., posted on December 22, 2014 at 18:37:10
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 The generalization is flawed. Consider a choke I/P filter. A large value, low ESR, 'lytic after the I/P choke is fine, regardless of rectifier technology. Remember that per older additions of the ARRL Handbook, LCLC is the way to go. A cap. that feeds small signal tube plates is an excellent candidate for metalized polypropylene film. Save the film and foil parts for signal path duty.

Given the intolerance of vacuum rectifiers to large valued cap. I/P filters, a MKP part as the I/P cap., when vacuum rectification is employed, makes sense. Dielectric absorbtion and other losses have to be minimized. Whatever energy is stored needs to be available.


Eli D.

 

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