Starting a Cornet2 and Introduction

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tubesforever

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Re: Starting a Cornet2 and Introduction
« Reply #20 on: 8 Mar 2009, 07:48 am »
Well at least the C2 is playing with the other children.  I was using the 1.25 ohm 12 watt wire wounds with 6.00 to 6.10 v at the heater.  With the Stealth Hexfreds I am just running a straight wire to achieve 6.0 v at the heaters.

The rectifier you select will bump up or down your B+ so don't touch your step down resistors for a while until you find a rectifier that does what you like for your system.  Then solder in the step downs that center your voltage points.

I think a slow on rectifier is best.  The Bendix 6106 has a nice slow smooth start up.  Get one of these if you can.

I don't know what is going on with the Piccolo.  Perhaps Jim has some ideas on where to look first when he is back from skiing in Colorado. Did you try all the potential gain steps to see if any of them provide output?

Two things to check....did you get the electrolytics properly oriented?  There is a square hole and a round hole for each cap.  You need to orient these to the proper polarity. 

Second the board needs a ground source.  I had to connect the earth ground point of the Piccolo to my earth ground star point on the C2.  If you have it hooked this way now, try lifting that ground because you might get ground from just the neutral RCA links from some posts I remember reading. 

I hope some of this helps. 

galyons

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Re: Starting a Cornet2 and Introduction
« Reply #21 on: 8 Mar 2009, 05:14 pm »
Well at least the C2 is playing with the other children.  I was using the 1.25 ohm 12 watt wire wounds with 6.00 to 6.10 v at the heater.  With the Stealth Hexfreds I am just running a straight wire to achieve 6.0 v at the heaters. 

Are you hearing a sonic benefit with the Stealth Hexfreds?  Seems the diodes followed by the caps tank should take care of the possible ringing of the diodes?


The rectifier you select will bump up or down your B+ so don't touch your step down resistors for a while until you find a rectifier that does what you like for your system.  Then solder in the step downs that center your voltage points.

I think a slow on rectifier is best.  The Bendix 6106 has a nice slow smooth start up.  Get one of these if you can.

I am using a GE brown base 6087.  It has a nice slow 20-25 second warm-up.  I bid a on couple of the 6106 on ePay, but got sniped both times.


I don't know what is going on with the Piccolo.  Perhaps Jim has some ideas on where to look first when he is back from skiing in Colorado. Did you try all the potential gain steps to see if any of them provide output?

Two things to check....did you get the electrolytics properly oriented?  There is a square hole and a round hole for each cap.  You need to orient these to the proper polarity. 

Second the board needs a ground source.  I had to connect the earth ground point of the Piccolo to my earth ground star point on the C2.  If you have it hooked this way now, try lifting that ground because you might get ground from just the neutral RCA links from some posts I remember reading. 

I was using the Piccolo, hardwired, in my Rogue preamp to step-up the signal before the factory phono board. It worked great and sounded fine for over a year.  I had to float the grounds to avoid hum. The only change I made was to take the zero gain to 6dB. There is no change, now, when the gain switch is changed.

I tried the star ground on the C2 and floating the Piccolo, neither made a difference.

I spoke to Jim last week. He suggested starting at the power input and testing voltages, per the schematic. I did and everything tested fine. Anyone know the pin voltages on the SMD's?

Cheers,
Geary

« Last Edit: 8 Mar 2009, 09:03 pm by galyons »

galyons

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Re: Starting a Cornet2 and Introduction
« Reply #22 on: 13 Mar 2009, 04:55 am »
I am a happy camper!  The Cornet2 is marvelous.  I have burned it in for about 48 hours. (Variable volume output CD player on repeat).  My current phono preamp is the board internal to my Rogue Audio preamp.  Firstly, the C2 is quieter, by far, than the Rogue board. The C2 tube rush level is below the level of the preamp linestage. Bear in mind that I am running a .65mV MC into the C2. Every critical evaluation point is better with the C2, with the exception of soundstage depth. Timbre, micro and macro dynamics, instrumental "air", quality and depth of bass.  I need to work a bit on the treble extension, may be tubes or my final output cap array. Too early to tell.

So....what did I put in?

Mostly a Tubesforever close cousin! (Thanks Jim!):

Kiwame 2w resistor, power path
PRP 1w resistors signal path
Russian KBG PIO 2uF bypassed by K40Y9 0.1uF for C200 & C206
K40Y9 0.1uF for C203, C102, CC211 (Yeah I know, overkill on these last 2, but I have'em in stock!)
K40Y9 0.047uF & 0.001uF for the RIAA caps
Sprague Vitamin Q 1uF with a Russian Teflon TF1 .022uF bypass. ( may need to take the Teflon to 0.1uF!)
GE 6087 Rectifier ( I tried a JAN CHS 5Y3 and it blew the 12AU7 upon switch to red. Perhaps the U7 was weak, but out came the 5y3 and back went the 6087!)
I burned in with  newish EH AX's & AU, but tonight tried RCA clear top AU and Siemens ECC83's, ( 1 is Halske, the other does not have the etched factory code, ( silk screened "221" on each side of the top, 2 top seams), not sure what brand  it really is, but the combo was very nice.

I got the bottom on the case and shields built and installed for the tranny wires. Virtually zero hum, or other noise.  The front panel was rough cut today.

I will try to post pictures.

My thanks to all for the input and support!

Cheers,
Geary






tubesforever

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Re: Starting a Cornet2 and Introduction
« Reply #23 on: 13 Mar 2009, 06:42 am »
Be patient with yours.  Everything is new right now.  And even new tubes take some time to take on a consistant voice.

I was very inpatient with mine.  After just two or three weeks I was ordering different caps.

Luckily for you, your caps are amazingly good caps.  I would try the 0.10 FT3 caps because at 1.22 uf at the final cap you are changing the frequency response to have less highs if I remember right. 

A Mundorf SIO will give you deeper, wider and taller sound staging.  The K40Y9 caps just do not go quite as wide and deep in sonics at least not in my system. 

Mullard 50's issue 12ax7 tubes will do space really well.  If these are  a bit pricy, then try out some Groove Tube Mullard reissues or the New Sensor Mullard reissues.  These are nice sounding 12ax7 tubes.  Pay extra for section matching.  It will be worth it in the end. 

My C2 is more forward sounding than either my Bedini 6677 preamp or my Precision Fidelity C7.  However it is a heck of a lot better in low bass response and it is a great deal more dynamic. 

I will give away a little depth to get the overall sonics of the C2.  BTW the Manley Steelhead, the Pass Xono, and the Wave Light line-phono stages run 6k to 10k dollars and they are just as up front.  What's interesting to me is that these high dollar Class A recommended pieces totally lack the SET midrange magic of the C2.

You also asked about the Stealth Hexfreds and I want folks to know that I would not use them again nor would I recommend them to others.  They did not sound any better or any worse and Jim tells us the Shottke's he specified actually ramp up a little slower preventing damage to the tubes at start up.

Just stay or go with the recommended Schottke diodes.  They sounded equal to the Stealth Hexfreds. 

Please be patient.  The sound does mellow, get widere and deeper, and just sound a little less edgy.  During the break in time it is a good time to buy up some tubes to roll later. 

Congratulations Geary!  You are definitely in for a major treat.

Cheers!

galyons

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Re: Starting a Cornet2 and Introduction
« Reply #24 on: 13 Mar 2009, 10:04 pm »
>snip
I would try the 0.10 FT3 caps because at 1.22 uf at the final cap you are changing the frequency response to have less highs if I remember right. 

Jim, the FT1 caps are 0.022uF.  The Vitamin Q's matched at 0.0978uF so I got a perfect 1.0uF with the FT1 0.022uF @ C208.   I have some FT2 0.1uF, but the lowest measured capacitance that I have a matched pair of is 0.10uF. So, I would be at 1.078 or 8% high. But, that is within the 10% +/-spec of the typical film cap, so, that may be my strategy.


Mullard 50's issue 12ax7 tubes will do space really well.  If these are  a bit pricy, then try out some Groove Tube Mullard reissues or the New Sensor Mullard reissues.  These are nice sounding 12ax7 tubes.  Pay extra for section matching.  It will be worth it in the end. 

I have pairs of the "Rodeo Drive Boutique" AX7's >>> Bugle Boy, Siemens and RCA Black Plate, but no Mullards or Telefunkens.  I have been on the hunt for Mullards.  The AX7's may be different, but I could hear no difference between Siemens ECC801's and Tele's 12ax7/ECC81 in my Rogue phono stage.


Please be patient.  The sound does mellow, get widere and deeper, and just sound a little less edgy.  During the break in time it is a good time to buy up some tubes to roll later. 

Patient my @$$!  I about "lost it" getting through the first 50 hours of burn-in!  I am burning in the Siemens now. They are NOS.  Initially, the sound was dry, flat and uninvolved, poor mid's and rolled off at both ends!   (Not exactly encouraging out of the box!)  I will give a serious listen after they have about 50 hours on them.


Cheers,
Geary

tubesforever

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Re: Starting a Cornet2 and Introduction
« Reply #25 on: 13 Mar 2009, 10:18 pm »
Geary,

I just put FT-3 back in the incoming circuit position.  That is the .10uf caps that sit up and down near the B+ bypass caps.

I had been running a Vitamin Q there for a few months.  The soundfield opened up a lot.  Smokiness has diminished and dynamics are improved.

If you have an extra set of the FT-2 in 0.10uf I would put them there to try them. 

They might do the same for you that they did for me!

tubesforever

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Re: Starting a Cornet2 and Introduction
« Reply #26 on: 14 Mar 2009, 06:32 am »
For Clarification:  I am recommending Teflons in C-203.  If you have FT-3 or FT-2 caps you will not be sorry you tried the teflons at this position.

Geary,  I like the FT-3 caps because of their huge surface area.  Just try an FT-3 0.10uf cap in the final output cap position instead of the FT-1 0.01uf.

Even at 1.1uf you should hear much better warmth and more natural highs.  I have to think the 0.01uf teflons are a bit bright.

What I love is the clarity and the dynamics.  They just seem to open up the 1.0uf caps so they sound more life like without destroying the overall solid and effortless presentation of the classic SET circuit.

Of course all of this is system dependent.....but I think you will enjoy teflons in the incoming and outgoing signal path positions.

Cheers!

BTW I received the 1.0uf PIO today.  They look like a Mini Me version of a motor run cap! 


galyons

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Re: Starting a Cornet2 and Introduction
« Reply #27 on: 14 Mar 2009, 11:27 pm »
Thanks Jim!

I am at 100 hours burn-in.  The Siemens AX's have 48 hours on them.  The combination is quite stunning.  As you, Guru that you are, predicted, everything has opened up and settled in.    My neighbor called to complain, the back of my concert hall is now sitting in his front room!! :wink: 

The base is solid and more impactful than the Rogue board.  Female voice is natural sounding.  The air around the instruments is creating a much more 3-D sonic signature.  The Siemens tubes are extended at both end, neutral in the middle.  I may try an RCA black plate AU insted of the cleartop.  Cleartops can be a bit crisp and analytical.

I will still try the Amperex & RCA, as well as source some Mullards. I tend toward a warmish mid, but I could happily live with the current tube mix.

I will keep the caps the same for , at least, a few weeks.  But, I like your idea of the FT2 0.1uF at C203.  That may be the first cap change I try.

Back to the music!  :thumb:

Cheers,
Geary

galyons

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Re: Starting a Cornet2 and Introduction
« Reply #28 on: 18 Mar 2009, 05:24 am »
Just an update on voltages, after about 100 hours.

GE 5* 6087 giving a B+ of 336VDC
1.25 ohm 12 watt Mills giving a H+ of 6.2VDC.

I have a Bendix 6106 0n the way.  I am guessing that it will be in the same B+ ballpark as the 6087.  What have others experienced?

Cheers,
Geary
« Last Edit: 19 Mar 2009, 12:21 am by galyons »

pretzel_logic60

Re: Starting a Cornet2 and Introduction
« Reply #29 on: 18 Mar 2009, 10:06 pm »
Speaking of tubes here I'm in the market for some more myself, both the ax and au. I have some older tele and mullard ax7s but believe they are close to worn out, they came with equipment I've bought over the years and are staticy, at least teles are. The Mullards have completely lost their markings and through 2 moves can't tell them apart, I had some au7s as well.

But what are a couple of the better vendors these days for decent NOS or even new tubes such as Jim mentioned above. I've looked at Tube Depot and Tube World, they have a nice selection but expensive, of course tubes have been going up in price a lot. The thing about tube world is they are the cyro treated, at least the early long plates and I don't need that. Tube Depot had some 70's Mullards but still over a hundred bucks each. I suppose e-pay is worth a look as well.

Brian

WGH

Re: Starting a Cornet2 and Introduction
« Reply #30 on: 18 Mar 2009, 10:28 pm »

But what are a couple of the better vendors these days for decent NOS or even new tubes such as Jim mentioned above.


Jim McShane always has some affordable NOS tubes, all his tubes are tested and he is a good guy to buy from.
http://pages.prodigy.net/jimmcshane/