CLARICORN: Combo Phono & Line Stage

hagtech · « **on:** 22 Oct 2004, 05:14 am »

Someone asked me not too long ago if a single power supply could handle both a Clarinet and Cornet2 at same time. Sure, why not. But the 370BX doesn't have enough heater to do the job. You may think it does rated at 2 amps, but that's an ac rating. When using rectified supplies for dc, a good rule of thumb is to have a transformer rated at double the current you plan to draw. Lots of losses with rectified dc.

The answer is to use a 372BX.

I made a prototype "Claricorn" using a big Lansing 19" chassis. Both boards fit nicely side by side. I used the power supply section on the Clarinet and left the Cornet2 side empty. Rest of circuits as-is, with the following changes:

1) Change R220 & R221 to 3.3k
2) Change R223 to 1.4 ohms
3) Change R313 to 2.0 ohms

Voltages work out pretty well. I connected output of Cornet2 internally to left-side input of Clarinet. This leaves two spare inputs. Also have to run wires for the B+ and H+ (and ground) between boards.

The back panel has split inputs, with phono way on the right.

You can get rack mount ears for this chassis for pro use.

jh

andrew · « **Reply #1 on:** 22 Oct 2004, 12:53 pm »

Hi Jim,

Looks good! Where did you buy the Lansing chassis from? Direct from Lansing or through a 3rd party? Oh, and what type/model is it?

Thanks,

JoshK · « **Reply #2 on:** 22 Oct 2004, 01:07 pm »

This was an idea I was thinking about too. 'cept I didn't figure on sharing the PSU but why not?

hagtech · « **Reply #3 on:** 23 Oct 2004, 02:39 am »

Chassis are only available direct from Lansing, 800-847-3535. This was P/N B2F12-V01B. Full rack width, 12 inches deep, side vents, black anodize.

jh

mgalusha · « **Reply #4 on:** 23 Oct 2004, 03:22 am »

Very nice! I've bought from Lansing a couple of times and have zero compliants about their product or service. Their site is: http://www.lansing-enclosures.com/

The chassis Jim used (and I use as well) is from the "gray box" series, style B.

BWentler · « **Reply #5 on:** 23 Oct 2004, 02:09 pm »

Could you install a power switch for the phono to allow the user to turn on/off the phono board when needed?

hagtech · « **Reply #6 on:** 24 Oct 2004, 05:30 am »

Well, I suppose it is possible. However, the common power supply depends on a constant load current for optimal operation and correct voltage & bias of tubes. If the phono is shut off, then the linestage ends up with too much voltage.

I suppose the Claricorn is only for systems that get a good percentage of vinyl play. Otherwise separate chassis is called for.

jh

hagtech · « **Reply #7 on:** 4 Nov 2004, 01:00 am »

In case anyone is interested, I just posted the ClariCorn for sale at Audiogon.

http://cgi.audiogon.com/cgi-bin/auc.pl?preatube&1100055516

Bidding starts at half price!

jh

coffeedj · « **Reply #8 on:** 9 Dec 2004, 06:24 am »

I've been running separate heater supplies for awhile on my amps, for the same reason that Jim mentions.

Since I separate my power supply from the main chassis I have a little more freedom. My solution is to use an 18V w/9V CT surplus transfomer that can handle 4 amps. I get these for $1 at my local Wacky Willies Surplus sales. The higher voltage and current rating lets me create DC heater current that is as clean as B+. Rather than a resistive drop I use an air coil, 12 ohms, making a kind pseudo PI filter. On the transformer side, I use a 3000uf, 35VDC cap, followed by ~1500uf 12V. Then a final resistive drop of 1 - 2 ohms depending on the number of tubes, and a 150,000uF cap. All these caps are surplus and around .50 to $1 each--they come out of old computer equipement. Makes a cheap and super DC heater supply.

ecir38 · « **Reply #9 on:** 16 Jul 2007, 12:27 am »

Jim, Would you possibly still have pics of this.

hagtech · « **Reply #10 on:** 16 Jul 2007, 01:22 am »

Ok, just fixed original post.

jh

ecir38 · « **Reply #11 on:** 16 Jul 2007, 02:45 am »

Thanks Jim, I am looking at building both and wanted to get a visual if I decide to go this route. Looks promising with less parts.

ecir38 · « **Reply #12 on:** 18 Jul 2007, 10:46 pm »

Quote from: hagtech on 22 Oct 2004, 05:14 am

I used the power supply section on the Clarinet and left the Cornet2 side empty. Rest of circuits as-is, with the following changes:

1) Change R220 & R221 to 3.3k
2) Change R223 to 1.4 ohms
3) Change R313 to 2.0 ohms

Also have to run wires for the B+ and H+ (and ground) between boards.

Jim, I think i am leaning more to the Claricorn and can use some clarification on a couple of things.

Digikey doesn't have a 1.4 ohm 5 watt resistor but they do have a 1.3 and 1.5. Would either of these be alright for R223?

I take it that both the left and right resistors need to be changed for R220 and R221.

Blue wire in the above pic goes from the positive for R313 to positive of R223.

Red wire in the above pic goes from the positive for R304R to positive of R220R(or R107 ?).

Black wire in the above pic ties the center terminal for V100 for both boards. I think this is used to help ground the two boards.

What size hookup wire are you using between the two boards?

I take that the heat sinks would be needed on the clarinet board.

Thanks and I look foward to this build in the near future.

hagtech · « **Reply #13 on:** 19 Jul 2007, 08:13 pm »

I forget what I did here. The blue wire is to connect heaters, brown (red) for B+, and then the black as return. This does create a loop with the signal input grounds, so this particular black wire may not be necessary. The 1.3 or 1.5 ohm values should be ok. 22 or 24 awg wire is fine. Heat sink shields are not as necessary as I thought they would be. Nice to have, but not mandatory.

jh