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zk1-betsy k's (Read 2438 times)
mkoepsel
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zk1-betsy k's
09/19/13 at 05:51:01
 
New here, first post.
I have some betsy k's in DIY MLTL enclosures. I previously used a RH-84 SEP amp with them. I liked the combo but, I'm wanting a SET amp.
I've read all the info on the Zkit1. It looks like it would work well with the speakers.
I have a few questions about the OPT's, Hazen Mod and Upgraded caps.
I read a post that stated the Hazen mod is on the new board. Is this correct?
Will the 6ohm 8k opt's be ok with the Betsy k's 8 ohm drivers? If not what should I use?
What upgraded caps are being used and where?

Looking forward to building the amp. Thanks for any info and help.

Mark
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Lon
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Re: zk1-betsy k's
Reply #1 - 09/19/13 at 11:59:34
 
Mark, no experience building and don't have an answer to your questions but wanted to say: Welcome.
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mboxler
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Re: zk1-betsy k's
Reply #2 - 09/19/13 at 14:43:01
 
Hey Mark

Welcome!  Here's what I know...

The Hazen mod IS on the new board, as well as the virtual CT for the AC heaters.  Hazen mod uses two of the 4 Cornell Dubilier Polyester Film Capacitors 400V .1UF in the BOM.

Not sure on the OPT's.  I'm using the 6 ohm OPT's into 8 ohm speakers...seems to work fine for me.

I believe Steve is now using the Jupiter HT-Series Beeswax Paper Aluminum Foil Capacitors for the coupling caps.

http://www.partsconnexion.com/capacitor_film_jupiter.html

They are $33.25 each (plus shipping).  I'm using them.  Can't remark on the improvement, but others may be able to discuss this further.  You can always try the Cornell Dubilier's first.  The upgrade is easy to do.  

Hope this helps.

Mike

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mkoepsel
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Re: zk1-betsy k's
Reply #3 - 09/19/13 at 16:42:52
 
Thanks for the welcome!
I saw the extra .1uf caps in the BOM. I was wondering where they went.  :-? Now I know.
Those jupiter caps are expensive. If I build this, I might use Russian k40's PIO caps.

On the PT, I wonder if I could use a real CT 6.3 instead of using the two resistors.

Mark
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mboxler
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Re: zk1-betsy k's
Reply #4 - 09/19/13 at 19:17:36
 
Yes you can.  Here's a link to an article that describes any small advantage a virtual CT would have.

http://www.valvewizard.co.uk/heater.html

Good Luck!

Mike
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mkoepsel
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Re: zk1-betsy k's
Reply #5 - 09/20/13 at 00:23:29
 
Hey that is a good link. Thanks! Both methods have their advantages.
I'm currently finishing up my Fender 5F1 clone amp. The zkit1 is next.
It takes Edcor a while. I'll get the PT and OPT's ordered.

I might simulate the PS in PSUDII. I'll see if I could add a LC section in the PS.

Mark
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mkoepsel
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Re: zk1-betsy k's
Reply #6 - 09/20/13 at 16:14:10
 
I have another question. On the Hazen mod the caps goes from pin 6 to pin 3 on the SV83. Does that sound correct? I looked all over the forum couldn't verify what's done.

Mark
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mboxler
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Re: zk1-betsy k's
Reply #7 - 09/20/13 at 21:10:16
 
Yes...between the cathode and the suppressor grid.

http://www.decware.com/newsite/paper145.htm

Again...the Zkit1 board has a place to solder the capacitor.

Mike
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mkoepsel
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Re: zk1-betsy k's
Reply #8 - 09/23/13 at 20:27:12
 
I have all the parts ordered. Just have to wait for edcor to build the transformers.

Mark
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mkoepsel
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Re: zk1-betsy k's
Reply #9 - 10/12/13 at 20:23:08
 
Edcors are here. Less than three weeks wait. Smiley  Bought some Russian k40 PIO.1u/400v coupling caps. I'm not going to use a choke with it. I saw somewhere here about using a 80u to 100u cap for the second cap in the PS. Can't find it again. I might add this mod.

Mark
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mkoepsel
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Re: zk1-betsy k's
Reply #10 - 10/24/13 at 02:44:51
 
Amp is finished and working great. Zero hum. I'd post a pic but, I don't have a photobucket account. Love the amp.  :)

Mark  
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« Last Edit: 10/24/13 at 03:54:14 by mkoepsel »  
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mkoepsel
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Re: zk1-betsy k's
Reply #11 - 10/25/13 at 02:19:19
 
Been letting the amp burn in. It just keeps getting better.
I bought a nos bugleboy 6DJ8. That really did the trick for me.

The amp works real well with the MLTL Betsy k's. Bass is tight and the speed of the amp is dead on.

MK
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mboxler
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Re: zk1-betsy k's
Reply #12 - 10/25/13 at 13:46:21
 
Congrats, Mark!

Other than the coupling caps, did you do any other mods?

If you have a picture, just attach it to your post.  The main issue is the file size.  I use Windows Paint to reduce the pixels, until the saved picture is below the 350 KB size.

Mike
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mkoepsel
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Re: zk1-betsy k's
Reply #13 - 10/25/13 at 15:28:55
 
Hey Mike,
The only other mod I made was a 100uf cap in the second PS cap. I'll keep trying on the pics. Still cant get it to work.

Mark

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« Last Edit: 10/25/13 at 15:30:07 by mkoepsel »  
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mkoepsel
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Re: zk1-betsy k's
Reply #14 - 10/28/13 at 18:03:50
 
Pic. I got it to work!  ::)

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