cornet 2 mod question

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beachbum

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cornet 2 mod question
« on: 31 Dec 2012, 01:59 am »
Hello all on the verge of building Jim's fine phono  amp. I would like to add the flexibility of multiple loading and capacitance values. Using the front panel location with rotary type switches for ease of changes. Ive read through several pages and haven't come across anyone trying this. Any thoughts or if any of you have how did it work out.  Thanks.Mike
« Last Edit: 31 Dec 2012, 03:31 pm by beachbum »

ptmconsulting

Re: trumpet 2 mod question
« Reply #1 on: 31 Dec 2012, 12:24 pm »
Are you confusing a Trumpet (which was never available in kit form) or a Coronet 2 (which always was available as a kit)? I believe the easiest way to do this would be to combine a Coronet board with a Piccolo board in the same case.


beachbum

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Re: cornet 2 mod question
« Reply #2 on: 31 Dec 2012, 06:00 pm »
ptmconsulting thank you for picking up on my mistake and your suggestion on my question. Mike

el34

Re: cornet 2 mod question
« Reply #3 on: 31 Dec 2012, 06:42 pm »
Now I'm confused, are you talking about cartridge loading?  I added variable resistance loading on the input of my Cornet at one point, I had 100k or 150k resistors or so in parallel with small trimmers of the same approximate value.

beachbum

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Re: cornet 2 mod question
« Reply #4 on: 1 Jan 2013, 05:07 pm »
Happy New Year to all.

Yes El34 that was what i was getting at. It seams you moved away from variable loading did it not work out.

With several MMs in my collection having flexible cartridge loading and capacitance settings would make fine tuning a snap and enhance musical satisfaction. Mike

el34

Re: cornet 2 mod question
« Reply #5 on: 1 Jan 2013, 11:27 pm »
Happy new year back atcha, and to the rest of the board.

I took out the variable R loading because I couldn't hear any difference, until going so low the input tube was affected.  But, I was working within the philosophy of make the C as low as possible first (I installed low capacitance cables to the turntable) which pushes the resonant frequency up.  I calculated it was around 17k or 20k or so, probably beyond what I can hear anymore.  Otherwise there were no issues with it.  Lately I've been experimenting with improving RF noise filtering on this and my other gear, which has been worthwhile, especially for my phono premps (lowest signal level of all gear.)

hagtech

Re: cornet 2 mod question
« Reply #6 on: 3 Jan 2013, 06:53 am »
RF is a tough problem!  I have 94.7MHz in my backyard (so it seems).  It shows up on most oscilloscope traces whilst probing.  I can hear it on all of my phono preamps if I touch the right parts on the inside.  My Tivoli radio tunes to it about every 3rd station... 

But if I can make a phono pre quiet here - it will be quiet anywhere!

jh

el34

Re: cornet 2 mod question
« Reply #7 on: 3 Jan 2013, 07:07 pm »
Hi Jim,

I didn't mean to imply I'm picking up radio stations, I'm not.  The Cornet is very quiet.  Just that I found the attention to the quality of shielding on the input connectors, and adding some extra power line filtering gave me a little extra smoothness in the highs.