[anumber1]

Hello all,

I have built couple of Cornet2's now, one for me and two for friends.

My unit is basically stock with the standard resistors and just a few upgraded caps (Angela tin & poly film for C200, C206, & C208, Auricaps for C203).

At first I was "wowed" by the increase in resolution compared to my ARC SP-6a's phono section but after a while I am finding the sound seems a bit "hard" at times. Overall I still think that the Cornet2 is a complete winner, I would just like to lean it towards slightly warmer.

Confession:
I personally prefer a warmer tone.

Associated equipment is a VPI HW19 MkIII deck with an SME 309 arm, a Sound-Smith re-tipped Denon DL-103 (ruby cantilever, line contact stylus), CineMag CMQEE-3440A step up transformers wired at 1:36 (37.5 ohm load into 47k ohms of the Cornet), The Cornet2, ARC SP-6a preamp, completly rebuilt Heathkit W5-M amps and Altec Valencia 846 speakers.

In the Cornet2 I am using a 40's vintage RCA 5Y3, an RCA 5963 in V202, RCA triple mica, black plate 5751 in V201 and a 50's Mullard long plate ECC83 in V200.

Using the 5751 in V202 has helped quite a bit in gaining some of the desired warmth. I am wondering if changing the B+ bypass caps to Russian PIO types (K40s) will matter that much?

Another confession:
I dislike the thought of buying 1 mF caps that cost more than $10 each (and $10 is a stretch).

What brought on the restlessness pertaining to the sound of my Cornet2 is that a buddy brought over his DIY phono preamp that is based on the Perpetuum/Ebner circuit from the mid 50's (from near the dawn of the standard RIAA EQ curve). That unit was really sweet sounding. Very warm yet still as detailed as the Cornet2. It also has four chokes in the power supply and was about 4x the cost of the Cornet2 to build in parts alone.

Where Should I Start when it comes to upgrading caps in the Cornet2? Any tube rolling suggestions? Do resistors matter that much?

Thanks for any and all suggestions!

Al G.

[tanchiro58]

Where Should I Start when it comes to upgrading caps in the Cornet2? Any tube rolling suggestions? Do resistors matter that much?

Since I had a Clarinet which is different than Cornet before I suggest you need to swap all caps in your Cornet2 with any of NOS vintage caps (cheaper) like Vit Q, Gudeman or West-Cap in signal path... Rolling rectifier tube with Mullard GZ34 or Phillip Miniwatt 5Y3 and replacing Kiwami or Allen Bradly resistors which are more warmer and musical sounding. Good luck.

[anumber1]

I did try a Mullard GZ34 and unfortunately found it to make the Cornet2 really dull sounding (my ears). Yes it was warmer but "too far" to the warm side of things.

Where do you think Allen/Bradley carbon comps would be the best fit without sacrificing the wonderfully quiet nature of the Cornet2? I have a good stock of AB resistors and will be able to match them up well.

[tanchiro58]

Where do you think Allen/Bradley carbon comps would be the best fit without sacrificing the wonderfully quiet nature of the Cornet2

Try them out at the tube sockets of input tubes first. For the GZ34 was too weak (not enough bottom) for my Clarinet and I used the Phillip Miniwatt which is the best tube of my taste. My clarinet was installed with Kiwami resistors. Besides Audience Auricaps are also good candidates in signal path or output.

[WGH]

What is your heater voltage? I found this reply by JH while doing research, it is in regard to voltage in a Cornet, but I believe the Cornet2 circuits are very similar:

[Low heater voltage effects the]"Transconductance ... and affects the EQ.  Basically, the unit will sound a bit softer and more rolled off, similar to a tube end-of-life situation.  With the higher heater, you'll hear a bit more punch and top end.  My theory is that you have to get the tube operating in it's sweet spot.  And heater has to be good for the rest of the design to work.  B+ is not quite as sensitive in this design."

And this:

"5Y3 has more voltage drop and results in a little softer sound, perhaps warmer.  Not bad, just a little different.  That's the beauty (and curse!) of rolling tubes.  You can fine tune the sonics for your personal taste.  You can make the Cornet aggressive or laid back, punchy or neutral, and can even tilt the tonal balance. 

There is no magic combination that works for everyone.  But certain trends are apparent.  The X7s work the tone and smoothness.  U7 the dynamics and slam.  Y3 the weight of tone and bass.  Tube dampers almost always help."

I used stock resistors in my Cornet2, there is a post by amandarae regarding his Cornet2 experiments:

"On the fourth week, I change all the stock resistors in the signal path with Rikens.  I run it for about a week and then listened for improvement.  IMO, there was none whatsoever."

Wayne H.

[hagtech]

anumber1,

It seems like you have too much front-end gain.  I'd start there.  Try reducing the trannys to 1:10.  Maybe even 1:20.  I think that will take the edge off.  To compensate, add some resistors in parallel with the 47ks.  Or just change out the 47k for something lower.  Like probably 4.7k.  Maybe a little up or down from that to tune the top end.

An interesting side note - playing with cartridge loading lately, I find I like it lower with SS phono and higher with tubed.

jh

[anumber1]

Hmmm,

Thanks for the prod Jim! The CineMag CMQEE-3440A transformer has three taps; 1:36 (37.5 ohms into 50k) 1:18 (150 ohms into 50k) and 1:9 (600 ohms into 50k).

Specs for the transformer may be found here: http://cinemag.biz/mic_input/mic_input.html

I have a switch wired so that I can select between the 1:36 tap and the 1:18 tap but have never added an 18k resistor to the 1:18 tap to make the loading equal between the two taps.

With prior experience telling me that I like the sound of the 1:36 tap better with phono preamps that have lower gain than the Cornet2, it didn't even occur to me that all of that transformer gain may be the "problem".

The "Hardness" is not a glaring fault, instead it is more of a personal taste/system synergy thing as I am a fan of the warm side of neutral.

I will try the 1:18 tap with 18k in parallel with the 47k resistor in the Cornet and see if that does the trick.

Thanks to everyone for the help!
Al G

[amandarae]

Hello Al,

I have my Denon retipped 103R(SME 3012/TD 124MKI) on the 1:18 taps of the Cinemag.  I am tracking at 1.5 gms and sounded very good.  At present, I backed up the VTF to 1.35 to 1.4 thereabouts and settled with it.  The Soundsmith website mentioned that with the Ruby cantilever, you only need to set the VTF from 1.0 to 1.5.

When I first got my Denon retipped, I set tracking to 1.8 and sounds very harsh/hard to me.  I left it there for three weeks and finally, when I had enough of the harsh/hard sound, I lower the VTF to 1.0 gms and heard an improvement right away.  After that, I listened with different force settings (1.2, 1.3, 1.4 and 1.5) varying the VTA for each setting until I come up with the current setting that works for me that I mentioned above.

I believe you when you say that a 5751 tube will tame the sound a bit.  It does because it varies the IRAA EQ curve (Rp of the tube).  But that should not be the solution to the problem.  In the first placed, the Cornet never sounded hard to me on my other cartridges (Koetsu, Benz, Denon 103/304, Shelter).

I hope you will find what's causing this "hardness" very soon.


rgards

[anumber1]

Ha! Thanks for the tip re: VTF!

I was tracking heavier than I thought at about 1.9 grams (by my Canrong electronic scale). I reset the tracking force to 1.5 grams and find the sound to be much more refined, the "hardness" tamed.

Since resetting the VTF I replaced the 5751 with a Dutch Amprex ECC83 and now have both resolution and warmth back.

I am left wondering how my tracking force got almost half a gram heavier tho. I had just remounted the cartridge on that arm a week ago. Perhaps it was too heavy from the start!