Starting a Cornet2 and Introduction

galyons · « **on:** 13 Feb 2009, 12:49 am »

Hi!
I'll start off by thanking the regular posters to this forum. A special thanks to Tubes4ever for some personal attention and feedback! I have learned much from lurking on the site. I have ordered the "kit" to build a Cornet2. This will be my second of Jim's products. I built a Piccolo and hardwired it into the phono section of my current preamp. Great board. Great sound! The Piccolo really cleaned up the noise floor and increased clarity, dynamics and extended the frequency ranges. I have modded my amps and preamp with Russian PIO & Teflon caps, pulled a lousy motorized, remote controlled volume pot and replaced it with a Dact stepped attenuator. So....the adventure in music continues!

Off on the adventure to build a C2. Everything has been ordered and I have received the DigiKey and Parts Connexion orders. The board will likely be here tomorrow or Saturday. The AES order , the vendor closest to me, but so far, the slowest of the bunch. I have some additional caps making the long journey from the former Soviet Empire. I will, again, use most Russian PIO & Teflon, caps, Kiwame, PRP and Mills resistors. I plan to pull the Piccolo from my pre and reinstall in the C2.

I am building my own case. I started today cutting all of the component pieces.

Thanks again for everyone sharing their cumulative wealth of knowledge!

Cheers,
Geary
SF East Bay Area

taskerc · « **Reply #1 on:** 13 Feb 2009, 03:31 am »

Welcome and enjoy the C2 Geary! I have the C2 and a piccolo and I must say they are very, very nice together. My system is hanging together better than I ever remember and for the first time in a while, I am not thinking about "the next upgrade".

Chris

galyons · « **Reply #2 on:** 13 Feb 2009, 06:00 am »

Thanks Chris!
I am really looking forward to the day that "I am not thinking about "the next upgrade". Seems like I "upgrade" one item and it magically highlights several others that need attention! Oh well, spending is good for the poor economy!

Cheers,
Geary

tubesforever · « **Reply #3 on:** 13 Feb 2009, 08:14 am »

Or you end up like me knowing that I need a bigger room.

I so totally agree Geary.

When your system opens up then you begin hearing the weak links. At least with DIY if you buy the right kit, you can tweak for decades and generally end up happy in the end.

Here is a big thank you to Jim H who continuously amazes me with his great products, his great support, and his unending tolerance while answering our diverse questions.

galyons · « **Reply #4 on:** 17 Feb 2009, 02:50 am »

Last week ended in a flurry of deliveries from the usual consumers of my discretionary income. I have almost all of the parts in. I started populating the board today. Got all the way down the "to do" list, sockets, quick connects, resistors, diodes, IC's, to the large electrolytic caps. The C2 PCB is a real joy to work on, especially after building a Piccolo with non-spec'd parts. All of that beautiful green real estate to landscape!

What is the latest recommendation on the rectifier tube. I have several 50's ish 5Y3's, (RCA, GE 5*, Sylvania, etc.). but seems that there are a variety of theories ranging from "Build it the way Jim said" to rolling in 5A4's. ( I have some nice Mullard 5A4's also!). Those of you that have used the Bendix 6106, I would appreciate your thoughts on it's contribution to the overall voicing, as well as the long warm-up ramp.

Cheers,
Geary

GRD · « **Reply #5 on:** 18 Feb 2009, 12:55 am »

My opinion only.

I own a few of the 6106 and have tried the various older RCA 5Y3's, 5V4's and a newer 5AR4. Each sounds different. The 5V4 and 5AR4 are "brighter" (a little more high end - maybe more B+?). The 5Y3 is more muted in the high-end, but I like it's balance. The 6106 is a little more muted in the high end than the 5Y3 (softer sounding than the 5Y3). It's all so system dependant, and all the other tubes add their flavor also. Even the source material makes a difference - bright records sound better with 5Y3 or 6106. Duller records benefit from the AR4.

That said, the 6106 is a beautiful tube and a real throw-back to 50's over-the-top engineering. Warm up time is like 30-40 seconds and it continues to warm up for a couple more minutes.

galyons · « **Reply #6 on:** 18 Feb 2009, 06:28 am »

Thank you GRD. I am more a mid range guy. Voices, strings, woodwinds and brass need to have the proper timbre. I will give up ultimate extension at either extreme for luscious mids. Interesting that, to you, the 6106 is softer, more muted than the 5Y3's. I've never heard one, (the 6106), and especially not in the C2 circuit.

My previous prime pre had a 5AR4 and swapping other rectifiers was not beneficial, though there was a big difference, (improvement), in going from the stock Sovtek to the various NOS 5AR4 I had on hand.

Cheers,
Geary

amandarae · « **Reply #7 on:** 18 Feb 2009, 07:51 pm »

Hello Geary,

Please include the RCA 5Y3G-ST to your tube list for the rectifier section. I thought the Mazda 5Y3GB is a very nice tube on the Cornet 2, but the RCA IMO is much better. Using this tube, from my notes, B+ is about 335V on my unit. I also have the 6106, Mullard and Amperex 5AR4's, Metal base Mullard 5AR4's, and 5Y3's from Sovtek, Sylvania, Crossley, NU etc.

They are the pairs (bottom) besides the Cunninghams and the Mazda 5Y3GB. The Cunninghams and RCA Victors are great too!

regards,

Abe

galyons · « **Reply #8 on:** 19 Feb 2009, 05:59 am »

Abe are the ST coke bottles taller that the run-of-the-mill 5Y3?
I dug out my tube stash.

I currently have:
JAN-CHS 5Y3GT Green Label Sylvania 1963?
RCA 5Y3GT 1958
GE 5-Star 6087/5Y3GTB 1959

Cheers,
Geary

amandarae · « **Reply #9 on:** 19 Feb 2009, 06:39 am »

Quote from: galyons on 19 Feb 2009, 05:59 am

Abe are the ST coke bottles taller that the run-of-the-mill 5Y3?

Cheers,
Geary

Hello Geary,

With the Sovtek 5Y3GT as the basis for the height (3-5/8 " ), the Coke bottle ST's (NU, Tungsol, RCA, Crosley, Sylvania, Cunningham, and Radiotron) are an inch taller at 4-5/8" with the exception of the Mazda 5Y3GB which is a little shorter at 4-1/2" tall.

regards,

Abe

galyons · « **Reply #10 on:** 19 Feb 2009, 07:00 am »

Quote from: amandarae on 19 Feb 2009, 06:39 am

Quote from: galyons on 19 Feb 2009, 05:59 am
Abe are the ST coke bottles taller that the run-of-the-mill 5Y3?

Cheers,
Geary

Hello Geary,

With the Sovtek 5Y3GT as the basis for the height (3-5/8 " ), the Coke bottle ST's (NU, Tungsol, RCA, Crosley, Sylvania, Cunningham, and Radiotron) are an inch taller at 4-5/8" with the exception of the Mazda 5Y3GB which is a little shorter at 4-1/2" tall.

regards,

Abe

Thanks Abe,
I am enclosing the tubes in a DYI case. Don't ask! I have a steady stream of kids in the house and do not want to worry about curious fingers. The upside is that I have lots of "landscape" horizontally for the big caps. But, I won't have enough depth for the ST's. I am mounting the tranny to the side of the case. I have approx. 5.5" total height, so I allowed 3.75" for the Tube side and 1.75" for the component side, including the PCB thickness.

All of my 5y3's measure, in the socket, at 3 1/8" to 3 3/8" height above the board.

Cheers,
Geary

jameshuls · « **Reply #11 on:** 19 Feb 2009, 06:08 pm »

Having tried all the usual suspects (and many others) in the C2 rectifier position, I eventually settled on a 1959 Svetlana 5C3S (analogous to the 5U4G) as the most musically satisfying. The various 5Y3GTs I tried out seemed stunted in comparison. Even a Mullard GZ34, a highly regarded tube (and hyper-priced to match), was outclassed by the tall Russian beauty. They can be had fairly cheap (I got 2 for $22) from those excellent Russian NOS ebay dealers (see link below to the dealer I got them from). However, it is quite a tall tube, so it may not fit in your custom case.

http://cgi.ebay.ca/RARE-1959-SVETLANA-5U4G-5C3S-BLACK-PLATE-TESTED-2_W0QQitemZ130285077480QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item130285077480&_trksid=p3286.c0.m14&_trkparms=72%3A1215%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

amandarae · « **Reply #12 on:** 19 Feb 2009, 09:08 pm »

Quote from: jameshuls on 19 Feb 2009, 06:08 pm

Having tried all the usual suspects (and many others) in the C2 rectifier position, I eventually settled on a 1959 Svetlana 5C3S (analogous to the 5U4G) as the most musically satisfying. The various 5Y3GTs I tried out seemed stunted in comparison. Even a Mullard GZ34, a highly regarded tube (and hyper-priced to match), was outclassed by the tall Russian beauty. They can be had fairly cheap (I got 2 for $22) from those excellent Russian NOS ebay dealers (see link below to the dealer I got them from). However, it is quite a tall tube, so it may not fit in your custom case.

http://cgi.ebay.ca/RARE-1959-SVETLANA-5U4G-5C3S-BLACK-PLATE-TESTED-2_W0QQitemZ130285077480QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item130285077480&_trksid=p3286.c0.m14&_trkparms=72%3A1215%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

Hello,

What works for you, works for you. I have no problem with that and in fact I am happy that you like how your preamp sound. But I have a concern.

Are you using 370BX power transformer for your Cornet II? If not, do you have a separate heater transformer for the rectifier?

You see, if 5C3S is the same as the 5U4 tubes, is it safe to say that it draws the same current as the 5U4 which is 3A?
If you are using a separate heater transformer rated at 3A, then there are "no worries" as they say but if you are using the Hammond 370BX where the heater current rating at the 5.0V taps are rated at 2.0 Amps, then I am a little surprise how it works.

This is the main reason why I cannot use the 5U4 tube in my preamp because I know it will load the transformer and possibly burn the 5 Volts(YL-/YL/BLK/YL) taps.

regards,

abe

jameshuls · « **Reply #13 on:** 19 Feb 2009, 09:55 pm »

Well, my C2 has only the 370BX transformer. I can't comment on why this tube is working, only that it is. Perhaps, in my ignorance, I have fooled my transformer into thinking it is a 370EX

galyons · « **Reply #14 on:** 20 Feb 2009, 05:09 am »

Thanks all for the input on the tubes. Looks like I will be a bit limited to the "short guys" in my rectifier rolling. I think I would like to try a 6106 along with my current stash.

I made headway today on the case. I am still waiting for a couple more parts to finish the board. The spec'd IEC inlet/switch is no longer a stocked item at Digikey. The replacement I ordered is a bit different, it is screw mount. I did not realize that one side of the switch pins are ganged to the inlet prongs. Shouldn't be a problem, I assume, as the gangs can be cut or just not use the jumpers as described in the assembly manual. I am a bit lazy, so I try it leaving the gangs in place.

Cheers,
Geary

tubesforever · « **Reply #15 on:** 22 Feb 2009, 08:04 am »

I have been enjoying the Bendix 6106 that ScottRT recommended as well as a Mullard rectifier I am using today. They are sonic equivalents and the Bendix 6106 is not terribly expensive. A slow start up is easier on the ol tubes! The Bendix does start up just right!

Cheers!

galyons · « **Reply #16 on:** 27 Feb 2009, 04:00 am »

I have finished the board, with the exception of the LED. The case is taking more time than anticipated. More planning and less "Let's get it on!" would have reduced the redo/redux! I will try to post pics, but can't seem to find the digicam!

Cheers,
Geary

Mr Ed · « **Reply #17 on:** 1 Mar 2009, 12:08 am »

Hi Geary

Dont do like me and put the LED backwards...mine goes green then red

I am really happy with mine and just added ft3 bypass caps, still burning them in.

Let us know when its up and running.
Ed

galyons · « **Reply #18 on:** 6 Mar 2009, 07:44 am »

Good news!
I powered C2 up today and all seems well. I have to work on getting the H+ dialed in. I am way off with the stock resistor @ 5.67v. I calculated that I'll need to go to 1.25 ohms. I parallel until I can order the proper Mills. I am about 10% down on the B+ test points, but may be my rectifier.

Case needs to top and bottom finished, but I can start the burn-in by the weekend! I'll post later about the "brain farts" that created, at this point, not humorous delays!

Cheers,
Geary

galyons · « **Reply #19 on:** 8 Mar 2009, 12:51 am »

The Cornet2 is working well. I have a bit of hum, but I will trace it out once I get the top and bottom on the case and I am not running a .65mV MC directly into the C2. So why would I run the MC directly into the C2?

Well... (S#!T), my Piccolo seems to have taken a crapper. I changed the zero gain to 6dB by changing the 2.2k in place of 4.75k resistor at the R2A position for each channel. Always on was already configured. Had the Piccolo nicely installed in the C2 case with wall wart power, but nada, none, "just hum the tune if ya' know it" at the output. I pulled the Piccolo and ran the I/O wires directly to the C2 chassis RCA's and she sings! She sings pretty well for carrying a much lower than spec cartridge signal.

I have checked all of my Piccolo voltage points and they test with the specs on Jim's schematic, but signal does not pass from the inputs to the outputs!

I work on it again tomorrow. Any thoughts or ideas would be most welcome!

Cheers,
Geary