Cornet3 Prototype

hagtech · « **on:** 3 Dec 2009, 01:16 am »

The EQ came out perfectly. Wow, I was a bit suprised. I nailed the calculations without having to make any changes at all. Did them several times for various B+ voltages and conditions. Ended up coming full circle after many paper revisions and it's pretty close to the original. B+ value is lower due to the inductively rectified power supply, so tubes are operating at a new bias point. Less voltage and less current, but with slightly more headroom. It also cuts the strain on the cathode follower's cathode-heater dc voltage down to 120V. That means more 12AU7 should have less trouble. I did try ac heaters, but no way can that be done. Final unit is very quiet. I can't do a full sonic comparison at the moment as I've sold off all my Cornet2 inventory (that which was in stock).

Anyway, I'm done with this unit. It's proved it's point. I'm selling it. If I do make a CORNET3, it will be in a different chassis, a 13.5 x 5 x 2 format with wooden sides. I'm hoping the magnetic orientations will allow internal CineMag step-ups. Sort of like this graphic:

Selling the prototype on Audiogon:

http://cgi.audiogon.com/cgi-bin/auc.pl?preaphon&1260410401

jh

roger15ohm · « **Reply #1 on:** 3 Dec 2009, 02:32 am »

Dear sir,

Is it possible to use the Cornet 2 board on this schematic? Is the power supply much different?

many thanks,

Wan.

PatOMalley · « **Reply #2 on:** 3 Dec 2009, 05:47 am »

This is beautiful. This is front page headline news for me.

Is this coming in kit or finished only form?

hagtech · « **Reply #3 on:** 3 Dec 2009, 08:57 pm »

Quote

Is it possible to use the Cornet 2 board on this schematic?

Sure - the chokes will have to be mounted off board.

jh

hagtech · « **Reply #4 on:** 3 Dec 2009, 08:58 pm »

Quote

Is this coming in kit or finished only form?

Haven't decided yet.

jh

GRD · « **Reply #5 on:** 3 Dec 2009, 11:54 pm »

Looks like this design is a "bridge" between the Cornet and Trumpet. Using LCLC for the B+ should make a very good B+ DC source - actually, best-in-class. Since the B+ becomes the output eventually, as described the C3 has an extremely clean power supply and should exhibit the best the design can offer. Considering the feedback on the current C2 design , this looks very promising.

Grant

roger15ohm · « **Reply #6 on:** 5 Dec 2009, 12:58 am »

Possible to have the schematic? Many thanks.

Bobzilla · « **Reply #7 on:** 5 Dec 2009, 04:24 am »

Jim,

As I'm just beginning to populate my previously purchased Coronet PC board, this would be a GREAT time to introduce this new schematic!

(It is the season for giving ... just a thought ...)

Bob

hagtech · « **Reply #8 on:** 7 Dec 2009, 04:14 am »

Still making changes. The EQ values and tube biases are good, though.

www.hagtech.com/pdf/sakuraschem.pdf

jh

roger15ohm · « **Reply #9 on:** 8 Dec 2009, 06:36 am »

With 2 chokes i believe it sounds more smooth? Huge decrease in B+ = less noise (quieter). Wow.... What are the changes you plan to make? Otherwise i thinnk i will stick with this one.

hagtech · « **Reply #10 on:** 8 Dec 2009, 11:01 pm »

Quote

Huge decrease in B+ = less noise (quieter)

Why would that be the case?

jh

roger15ohm · « **Reply #11 on:** 9 Dec 2009, 12:51 am »

Just some very basic knowledge when performing hard soldering before in diy project and some reading, that i am not sure about too. Just mark me if i am wrong. Missed a question mark after that sentence.

Bobzilla · « **Reply #12 on:** 9 Dec 2009, 02:16 am »

Jim,

Two questions come to mind:

Are the CineMags required for the general purpose phono preamp or just for those using low output moving coils?
Do you have a source for those chokes?

Many thanks for sharing the schematic so early in development!

Bob

Brinkman · « **Reply #13 on:** 9 Dec 2009, 03:39 am »

Quote from: Bobzilla on 9 Dec 2009, 02:16 am

Do you have a source for those chokes?

Hope you don't mind me chiming in here, but the chokes are Hammond 155Js, available from Parts Connexion for about $18 each.

Bobzilla · « **Reply #14 on:** 9 Dec 2009, 05:06 am »

Brinkman,

Great info, thanks!!

Bob

hagtech · « **Reply #15 on:** 10 Dec 2009, 01:20 am »

You can order CineMags directly from www.cinemag.biz.

The more I look at the layout, I don't think they're going to work. The spacing from the power tranny is pretty good, but the 1st choke in the power supply shoots too much magnetic field, too easily coupled not just into the step-up trannys but also into the input wires. I think it might end up an MM design only. The 47k input impedance solves the cable coupling problem. Either that, or use a much bigger chassis. That's one drawback of the choked supply - more stray magnetic fields!

jh

gnnett · « **Reply #16 on:** 14 Dec 2009, 08:12 am »

Jim

As one of a handful of Cornet 1 split users, I think you should consider this as an option to address this particular effect of the power supply chokes.

Regards
Gn

tubesforever · « **Reply #17 on:** 14 Dec 2009, 09:12 am »

Jim I think its time to consider a two component phono section. The power supply in a separate case, and an umbilical to feed the MM or MM/MC stage.

I love my Piccolo. It sounds better than a Cinemag with PRP resistors and Black Gate caps. Why not let folks build in either a Cinemag or Piccolo into the phono stage board, free from the EMI coming off the Hammond transformers?

Selling two boards is not a discouragement to diy folks. In my line of thinking its genius. Its how a phono stage should be done. You will be elevating the C3 to a higher eschelon of equipment and that is a good place to go with your Hagerman brand. You could go with a torroidal transformer. That would be a welcome improvement.

Heck I will be among the first to build one. That's for damn sure!

Happy Holidays Jim!

flocchini · « **Reply #18 on:** 14 Dec 2009, 03:20 pm »

I really like the separate power supply concept. My C2 (hybrid octal - love the 6SN7) and the Piccolo is such a great combo. It would be a great experiment to try to improve it. C3 hybrid octal - hmmm

Best and happy holidays.

Bob

Bernie · « **Reply #19 on:** 14 Dec 2009, 05:26 pm »

Hi Jim, I also would like to join the seperate power supply club. I believe when a very good amplifier circuit design is implemented, a well designed power supply with limited compromises, is the device that adds the ultra magic to the sound quality. I hope and trust that you can find it within your self to offer a seprate outboard power supply for the cornet 3. I'm sure it will take a lot to largely improve on the CORNET phono stage without having to break the bank, but I hope you will go for it. Let's really kick it up.

Bernie.