hybrid common cathode amplifier?

[mwmitchell]

Have any of you tried this?

2 triodes, cathodes direct coupled to a MAT-02 device(dual matched bipolars), the MAT-02 share an emitter resitor to a -15 v supply (Allen Wright?).

The grids of the triodes are biased for the MAT-02 device and a.c. coupled to ground.

both plates have same values for plate resitor, however one is a.c. coupled to ground.

read if interested (it is interesting!):
http://www.glass-ware.com/tubecircui...lifiers_3.html
for more info on common-cathode amplifiers

what I'm trying to do is use this as a microphone input amplifier, balanced to unbalanced (next stage would be an eq circuit).

so, this is kind of a grounded grid amplifier, but kind of a common-cathode as well (?).

Could this circuit possibly work well? (Sorry, I can't try it - no power supply at the moment).

Thanks for any info!

-Matt Mitchell

[halojoy]

I was at your lnik.
Nowhwere I found the mic-pre-amp
using the low noise MAT-02

So, You have no Drawing of the Circuit
you think about.
Makes it Hard or Imppossible to Discuss.
---------------------------------------

My solution is, Exclude the tubes,
and use low noise Bipolar Transistors,
Will get more High Fidelity and less trouble in construction.
----------------------------------

If you want Tube sound , with distortion.
Use your Hi-Fi recordings,
but add that distortion with Tubes
when your PLAY your material.

If you add distorsion form the beginning,
then you have no choice later.

Choice between Hi-Fi or Tube-distortion.

/halojoy - waits to duscuss, til you present your idea
in a better way - with at least a principal Schematic

[mwmitchell]

OK, sorry about that. Here is there circuit I was talking about. I have no idea if this will work (no values really, just the basic idea)

Thanks!!

- matt mitchell

[NickC]

looks like a cascode long tail pair( differential input)stage ala allen wright style. which comprise of both grounded grid for top stage and common cathode for bottom stage.
can work for balanced to unbalanced or vice versa
best part about this circuit is u can apply feedback to the tube grounded to ground thus allowing the other tube to just to do the voltage work.
i think allen uses this work his pp1 amp but is configuration is for unbalanced to balanced(push pull)

[halojoy]

Originally posted by mwmitchell
Have any of you tried this?

2 triodes, cathodes direct coupled to a MAT-02 device(dual matched bipolars), the MAT-02 share an emitter resitor to a -15 v supply (Allen Wright?).

The grids of the triodes are biased for the MAT-02 device and a.c. coupled to ground.

both plates have same values for plate resitor, however one is a.c. coupled to ground.

read if interested (it is interesting!):
http://www.glass-ware.com/tubecircui...lifiers_3.html
for more info on common-cathode amplifiers

what I'm trying to do is use this as a microphone input amplifier, balanced to unbalanced (next stage would be an eq circuit).

so, this is kind of a grounded grid amplifier, but kind of a common-cathode as well (?).

Could this circuit possibly work well? (Sorry, I can't try it - no power supply at the moment).

Thanks for any info!

-Matt Mitchell

thanks Matt

Sorry that I personally knows so little about tubes.
But in this circuit MAT-02 transistors
are setting the performance, while the tubes
are cascoding and providing an output.
Will you use FEEDBACK?

[reinhard]

Nothing more than a differential cascode, will work.
Reinhard

[mwmitchell]

I would use feedback if it helped the circuit out sonically. Can you tell me more about how I would use feedback here? the grounded grid?

Also, can anyone tell me how this circuit rates as a balanced to unbalanced conervter?

Thanks for all of the help everyone!

matt mitchell

[halojoy]

I would think it is a Good circuit
WITHOUT the TUBES

I am not so sure about the good of feedback here
or how to make it.

/halo is somewhat confused by this idea

[Brett]

Originally posted by mwmitchell
I would use feedback if it helped the circuit out sonically. Can you tell me more about how I would use feedback here? the grounded grid?

Don't use feedback, it doesn't need it. I use exactly this circuit with an MAT02 and 6DJ8 for a 300uV phono cart. It's very linear and gives about 60dB of gain and sounds stunning. You'll need a buffer line driver for the output. One of the simpler VSE circuits will do, as would a simple common cathode differential with an output transformer like a Lundahl LL1660.
Allen Wright uses them as mic preamps too, and so will I eventually for the Studer tape machine I'm building.

Also, can anyone tell me how this circuit rates as a balanced to unbalanced conervter?

Never done it, but I expect it's quite good, just make sure that both outputs see the same load, and just tap off one for the phase you want. You still need the buffer as the output Z of a cascode is quite high.

[Brett]

Originally posted by halojoy
I would think it is a Good circuit
WITHOUT the TUBES

Huh?
It's an excellent circuit. Period.