[orpheus]

I have been thinking about building a balanced preamp, but there aren't many options available. Tube preamps rarely have balanced outputs, and when they do, they are very expensive.  My amplifier has a balanced input, and I like the idea of a balanced connection between the preamp and amplifier.

Would it be reasonable to make a balanced Clarinet?  I assume I would need to use two boards, using one channel of + and - instead of L and R on each board.  Would any modifications to the board be necessary?  Could one power supply be used, or would two be necessary or so much better as to make two worth the cost?  How would unbalanced sources be connected to such a contraption?

Would it be possible or beneficial to build a balanced Coronet in a similar fashion?

Thank you for your suggestions.  Perhaps someone else has already considered this possibility. 

-Aaron.

[Ferrstein]

Dualing Clarinets would be very cool!  The problem with that topology is that it doesn't take advantage of the differential balanced input... just the balanced input.  In other words, you don't get the noise rejection you get by summing up the signal at the input of the preamp.

I have a rather strange application where I run two amplifiers out of phase (I have direct-drive Acoustats, with one amp powering the front stators and another powering the rear stators with a 180 degrees out-of-phase signal).  I, too, want to use my Clarinet as a preamp but I need a balanced output.

What I've done is purchase some Sowter 8920 transformers.  These can be setup to provide about a 15k input impedance (a bit low for the Clarinet on a long cable run, but doable nonetheless).  The trannys then put out two signals that are 180 degrees out-of-phase.  This can of course work as a balanced output. 

Hope this helps.  I believe either Sowter or Jensen also make transformers that can sum a balanced input for use with the Clarinet if you so desire.

[hagtech]

Yes, ferrstein is right.  The only way to make a CLARINET balanced is to add an output tranny.  You might want to try a 2:1.  Or get one of than many good 1:1:1:1 from lundahl, sowter, jensen, or cinemag.  Put the primaries in series, drive it with the CLARINET output.  The secondaries also in series with the center tap grounded.  Works like a charm.  I believe Audio Note does it this way.

Trying to run dual CLARINETs is useless, as you end up with two completely uncorrelated signals.  On the other hand, I would make more money.

jh

[randytsuch]

Yes, ferrstein is right.  The only way to make a CLARINET balanced is to add an output tranny.  You might want to try a 2:1.  Or get one of than many good 1:1:1:1 from lundahl, sowter, jensen, or cinemag.  Put the primaries in series, drive it with the CLARINET output.  The secondaries also in series with the center tap grounded.  Works like a charm.  I believe Audio Note does it this way.

Trying to run dual CLARINETs is useless, as you end up with two completely uncorrelated signals.  On the other hand, I would make more money.

jh

I am sure I oversimplifying this, but I was wondering why you could not run dual Clarinets, one for the left side, and one for the right?
I would use one to drive right low and right high.  The other would be used for left low and left high.

Of course, balance would probably have to go away, the input switching gets much more complicated, and you need a 4 gang volume pot, so basically the whole front end of the clarinet would be changed/not used.  You would have to add you wire in your own input selection, and the 4 gang pot, then just use from C302 on.

Is there a reason this would not work?

And speaking of balanced Hagtech things, I was considering at some point building a balanced castanet.  Again, I would use one castanet for left, and one for right.  I was thinking I could rewire the output transformer, and drive both ends of the input side, one with the high signal, and the other with the low signal.  On the output, I would just lift the transformer from ground.  I know this is an expensive proposition, which is why I can't do it at this time, but I thought this would make an outrageous balanced tube can amp.

Randy

[hagtech]

Is there a reason this would not work?

Sure it would work.  But I can't understand why anyone would choose to do so.  It's like going to the movies, you and your girlfriend each take separate cars.  Yeah, it works, but really, it's better if you both take one car.  Unless your wife sees you.

Dual CLARINETs is like strapping two motorcycles side-by-side, trying to make one machine.

some point building a balanced castanet

The CASTANET output already is balanced, sort of - just disconnect the 0 ohm tap from the ground plane.  Add the common mode connection by a resistor to ground on each lead.

jh

[randytsuch]

Is there a reason this would not work?

Sure it would work.  But I can't understand why anyone would choose to do so.  It's like going to the movies, you and your girlfriend each take separate cars.  Yeah, it works, but really, it's better if you both take one car.  Unless your wife sees you.

Dual CLARINETs is like strapping two motorcycles side-by-side, trying to make one machine.

I was trying to answer Orpheus' original question, if you could build a truly balanced clarinet.  And, I think you can, using the method I described.

For Orpheus, since he does not have a balanced source, I would agree that it may not be worth the effort.

BTW, I like the wife sees you joke.

The CASTANET output already is balanced, sort of - just disconnect the 0 ohm tap from the ground plane.  Add the common mode connection by a resistor to ground on each lead.

jh

Yeah, but does not help what I am trying to do.  I would have a balanced source, based on a squeezebox.  I would want to feed that balanced source to a fully balanced headphone amp, one that has basically the same circuit for the negative and positive feeds from my balanced source.  I have yet to try balanced, so I have don't know if would be worth the cost and effort, but it is something I want to try out, and was wondering if I could do it with a Castanet.

Orpheus/Aaron
If you think I am starting the hijack your thread, let me know, I am will start another thread, if needed, to discuss the possiblity of a balanced Castanet.
And, if you are interested, I did find a link the other day to an article about building a balanced phono amp.  I could find it again if you are interested. 


Randy

[hagtech]

I had to think about this one.  It does appear you can make a fully balanced in-to-out CASTANET with the dual monoblock approach.  You could simply re-wire the tube output through the 3.3uF so that one phase is as shown on schematic, and then return the primary to the other phase, rather than the cathode.  You could improve upon this by inserting some sort of CCS and make the tubes into a differential pair.

jh

[Yoda]

The CASTANET output already is balanced, sort of - just disconnect the 0 ohm tap from the ground plane.  Add the common mode connection by a resistor to ground on each lead.

jh

What value resistor would be reasonable?

[tubesforever]

Jim,  the Clarinet is a stand out piece in my audio system.  While no line stage could be perfect, it really delivers magic with every source I throw its way.

Could you develop a new product in dual boxes, power supplies in one and balanced SRPP typology in the other?

Knowing the success you achieved with the Trumpet, I figure it would be possible with a Clarinet 2!

I would love to build a fully differential balanced line stage. 

I also need a DAC that accomplishes SACD, DVD-A and Redbook CD. 

[analog97]

Could you develop a new product in dual boxes, power supplies in one and balanced SRPP typology in the other?

Knowing the success you achieved with the Trumpet, I figure it would be possible with a Clarinet 2!

I would love to build a fully differential balanced line stage.

I also need a DAC that accomplishes SACD, DVD-A and Redbook CD.

Poor Jim!!  He likely has a plate that is full beyond imagination.  My hope is he's working on a 100+ watt tube amp.   

[tubesforever]

Not speaking for Jim, I remember him saying that amplifier circuits are out there, work great and why does he need to enter a congested marketplace.

I admire his foresight and agree with his philosophy. 

He did build a low wattage zero negative feedback amp.  I just think he pulled it from current offerings.

I need to build some horns next.  I want to have 100+ db with a single watt driving the beast.  That would run with Jim's power amp.

Cheers!