[gnnett]

Well, superb layout.
I even like the idea of output sockets close to the rear of the preamp "board".  My "Cornetto Split" C1 has input and output sockets on the top and while the input works well with the Bent Mu's, output locations are a little awkward. Damn it I'll pick up a sheet of 2mm teflon and build a batch of adaptors if no one makes them. My chassis Octal socket with short wires looks awful, but no one can see it.

Great work and looks like I now have a winter project.

Cheers

Grant

[flocchini]

One adapter source

http://cgi.ebay.com/Adapter-6SL7-6SN7-TO-12AX7-12AU7--tubes-SUB-_W0QQitemZ250546630488QQcmdZViewItemQQimsxZ20091212?IMSfp=TL091212044003r16981#ht_1572wt_1167

[danlaudionut]

New to this site from AA.
Just to add my 2 cents here.
I built the Octal Cornet with modifications.
I do love this guy - a real keeper 
PS is cLC with a 2K then 2-150V VR tubes
in a seperate chassis for the 300V B+.
I had some 1Hz voltage instability.
heard when the song faded out.
Cured it with an LC per stage.
Working great now.
Also used a choke loaded 6P5/6J5 GC
for the final stage instead of the CF.
The choke replaced the 220R on the
plate of the 6SN7 final stage.
A .68uFd Mundorf Silver/Oil to
the output RCA with 1Meg load.
I used a 40uFd GE MR to bypass the
15K cathode resistor on the final stage.
I used Riken for the gate stoppers.
Shinkoh for the series resistors.
Kiwame for the loads to grd and B+.
Mills for the cathodes.
Obbligato for the 47nFd caps.
Silver/Mica for the 1nFd cap.
K40Y-9 for the 1st PS cap.
60uFd GE motor run for the 2nd.
Magnequest BCP-15 for the choke.
Other BCP-15 with 100uFd Solen after
the VR tubes for the output stage.
Hammond 157G and 40uFd GE MRs
for each of the 2 other stages.
Filament was Hammond T16712
with UF4007 rectifiers and 680uFd
then the Bottlehead FC-1 CMC
finally about 20mFd of capacitance.
I figured that since I used your
schematic (well mostly) I should let
you guys share in my work.  aa

DanL

PS Teflon Octal Sockets used through out.

[GRD]

DanL,

Over The Top!!!!  To say I'm impressed is an understatement.  You must have the quietest and locked DC on the planet.  Cap and resistor component choices are localized based on the circuit.  Some real thought went into it.  Can you post some pictures? 

Grant

PS  And I got lost on "GC".  Can you provide a little more here.   I'm interested in how you replaced the CF.

"Also used a choke loaded 6P5/6J5 GC
for the final stage instead of the CF."

[danlaudionut]

Grant

Thanks for the praise.
I have been tinkering with it for about a year.
An old schematic is here -
http://www.integracoustics.com/images/DanL/OCTAL_CORNET.GIF
I haven't taken any photos of it yet.
GC = Grounded Cathode

DanL

PS Any one can email me for the recent schematic
Moniker at AOL DOT com

[GRD]

DanL,

Wow!!!!   Thanks. 

Grant

PS - and another question - the GE 97F between the B+ and the cathode of the final stage.  I've not run across this before.  What does it do (improve PSSR?).

[danlaudionut]

Grant

The 97F is an ultrapath capacitor.
It takes the cathode resistor AND the PS
capacitor out of the audio circuit.

DanL

[analog97]

Why are there about 56 resistors in the Cornet2 and only about 39 shown in the new layout?   

[tubesforever]

It looks like he is using less voltage to accomplish the same circuit.  So the drop down requirements are less.  I think the voltages are in the order of 220 on the B+ rail.  He used double drop downs to provide greater safety to the circuit if the power supply melts down.  Two series resistors do effect sonics.  So eliminating unnecessary resistors is the way to fly.

Analog97, the important thing is how many resistors are sitting in the direct signal pathway.  He has cut this down and it should make for better sonics.  If thats even possible .

I love the Cornet 2.  I suspect the Cornet 3 will be an instantaneous winner.

danlaudionut....You are an inspiration for diy.  And thanks for your help in sorting out some crossover issues I was working through last year. 

I would love to see pics of the work you have done.  Did you bread board the C2 hot rodded power supply and circuit?

[analog97]

Analog97, the important thing is how many resistors are sitting in the direct signal pathway.  He has cut this down and it should make for better sonics.  If thats even possible .

Thanks for your reply, Tubes!  I don't know how many of these resistors JH eliminated are in the "direct signal pathway".  If there is enough space on the new C3 board, I am gonna start shopping for some 2-watt Kiwame resistors and get ready for my next build.  As I write this, I am listening thru my C2/Clarinet/VPI MK-IV/PICCOLO/Denon 103/Parasound A21/Polk SDA 1.2TL's to Peter Gabriel's "The Car" and wondering....can it sound better than this?

[hagtech]

only about 39 shown in the new layout?

Maybe because I forgot to add the LED circuit.    And different power supply bleeders and surge removers.  Signal path is very similar.  I had to adjust all tube bias points for the lower B+, re-do all the EQ too.  I can only think of three resistors per channel removed from signal path (the 10k in 1st stage EQ, removed 220 ohm from plate of cathode follower, and combined function of 220 ohm output cushion into CCS). 

jh

[danlaudionut]

danlaudionut....You are an inspiration for diy.  And thanks for your help in sorting out some crossover issues I was working through last year. 

I would love to see pics of the work you have done.  Did you bread board the C2 hot rodded power supply and circuit?

Tubes

I don't know about inspiration but
I guess you could call it persistance  aa

I will try to get some pics hosted.
I don't know the C2 design as I only
started with the Octal Cornet cicuit.
Then I modded it to LCLC PS.
It had some low frequency oscillations
as well as some hum problems.
Then I went to a seperate PS chassis
and that eliminated the hum but
the low frequency oscillations persisted.
Then I went to VR tubes and that
didn't cure the problem in fact
it made much worse.
So I tried an LC after the VR tubes
(one per channel) and it was still there
but less than the VR tubes alone.
I concluded it must be motorboating
at about 1Hz so I tried  LCs per stage.
Decoupling each stage from each other.
I slapped in the extra Magnequest choke
that I removed when I went to VR tubes
and I had a monster 100uFd Solen just
sitting around and I decided to use that.
So I have 1 Hammond 157G and
a GE MR 40uFd Cap for both first stages.
And another one for the second stages.
And the MQ BCP-15 and 100uFd Solen
for both final stage's  filter.
cLC then VR tubes and three LCs worked.
Now all is fine and sounding great. 

DanL

[JayB]

I vote for the Piccolo/C3 in one chassis and their power supply(s) in another. How about a phase switch? Include all of the option discussed on this thread. If you don't want them then you wouldn't hook them up. It would just be nice to have the options available.   

[Brinkman]

I vote for another differential phono stage such as the Trumpet; this time implementing the lower B+ tweaks he's applying to the Cornet3.

[tubesforever]

Brinkman and I must think alike....

However, I see the need for a common grounded C3 and a true balanced phono kit.   

I salivate the most thinking about a Trumpet like kit.  My plans in the future are to run fully balanced line stages and amps.  I would like my phono stage to reject common mode noise as well.

However most diy types are going to be happy as can be with a common grounded phono section.  The deserve what the C3 can deliver.

So JH can you swing both designs?

[Bill Epstein]

I wonder if some of us here are unaware of the ultimate cost of combining the Clarinet and Cornet in a single box with separate power supply? It's one thing to take Jims boards and/or schematics and build, as Danlaudionut has, their 'dream' Hagkit, quite another for Jim to produce it.

I vote for the Piccolo/C3 in one chassis and their power supply(s) in another. How about a phase switch? Include all of the option discussed on this thread

Not to pick on Jay, it's a good idea, but this product already exists at a pretty fair price, a used CAT SL-1 Mark III! It's not balanced but in many ways is still a benchmark. That pretty fair price, BTW, is about $3000 for one more than 10 years old!

I'm all for a balanced phono stage; back in my reviewer days I had the priviledge of auditioning the AQvox 2Ci and balance wiring my then SL-1210 table to take advantage of the AQs balanced configuration. You think you've heard quiet? Fuggedaboutit!

[poty]

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

Is it possible to get what exactly p/n is the CineMag? I followed you link and found some CMQEE-3440A - is it correct?

B+ value is lower due to the inductively rectified power supply, so tubes are operating at a new bias point. I'm hoping the magnetic orientations will allow internal CineMag step-ups.

Just thinking... If the small decrease in B+ affect the bias point, so it maybe necessary to make the B+ more stable with some stabilizing circuit? Like that on danlaudionut... It would help to get most from the layout.

... CineMags ... 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.

I think in that way I agree with JayB (originally this idea comes from tubesforever) about incorporating Piccolo as MC stage. It helps to get variable loading and variable gain too. It eliminates a lot of problems with magnetic fields. It gives flexibility and simplicity to the "main" C3 scheme (eliminates volume control and loading switch). For purists there can be separate "pure 47 kOm MM" RCA jack.
I vote strictly FOR the design with separate power supply (as suggested by tubesforever and supported by flocchini, Bernie and others)!

Dug open my old notes for variable EQ...
The problem is switching into position will cause a huge "tic" or "thump" in the output.  I thought of maybe keeping the unused positions charged up with a 1M bleeder, but this would only screw up EQ in the bass region.

I think there is no problem at all. You can connect the bleeder as soon as the circuit is not connected to the signal path. And disconnect it (the bleeder resistor) with help of the second pole of the switch just when the circuit is connecting. Then you don't want to get volume to minimum while switching the EQs. And it helps not to use potentiometer in the signal path (switched resistors are the best!).

I vote for another differential phono stage such as the Trumpet; this time implementing the lower B+ tweaks he's applying to the Cornet3.

The cartridge itself is not balanced, so the signal should be artificially converted for phono stage. The only way is a transformer, but there is additional inductance involved and nobody knows which is better - good unballanced phono stage or several addition non-linear parts in the signal path.

[Bernie]

Has it been decided that Jim is going to offer a Cornet 3 half kit for sure?

Bernie.

[hagtech]

I think there is no problem at all. You can connect the bleeder

I don't like this.  It's not about bleeding to ground.  You have to bleed to the signal path that's in action.  I don't want to put any extra parasitic RC time constants onto a live EQ.  Sorry, I'm a bit anal about that sort of thing.

Has it been decided that Jim is going to offer a Cornet 3 half kit for sure?

If anything, it's a long time away.  I just can't get to it right now.  Can you imagine - I have a C3 board prototype mostly stuffed with parts - and it sits in a box.  It feels very ignored and abandoned.  Poor thing. 

jh

[poty]

I don't like this.  It's not about bleeding to ground.  You have to bleed to the signal path that's in action.  I don't want to put any extra parasitic RC time constants onto a live EQ.  Sorry, I'm a bit anal about that sort of thing.

Why do you think I offer to bleeding to the ground?    And - NO - you do not have to bleed to the signal path either. You know very well the voltage on the anode of the V3A - 120V (it is mentioned on your scheme). You can get the voltage with very simple resistor potential divider between the plus condenser armature of the C10 (left side of the R18) and the ground. AND the circuit will NOT be in the LIVE signal path.

Meanwhile there is a difference in EQ circuit values between your post #44 and the scheme on post #54. Which is the right one?