transconductance amp

[Pars]

I could probably be into trying one of those with my orthos. See if it can unseat the DynaFET...


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[jose]

 

1 hour ago, Pars said:

I could probably be into trying one of those with my orthos. See if it can unseat the DynaFET...


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I have my doubts about that ... However, the interesting thing (for me) is to try it.

[sbelyo]

anyone have a pair of these boards?

[jose]

First, thanks to Dr. Gilmore and Soren!

My amp is working and everything is OK. It's perfect with low impedance and miserable sensitivity headphones. 

B: +/- 29Vdc

~2.1/50=41mA (L) 43.2mA (R)

~2.2/562=3.7mA (L) 3.9mA (R) 

Voltages are a bit lower than Congo5 but I think it´s correct.

I start working on the chasis now. I´ll install a switch to select the gain as I did in the SquareWave.

P.S. I know I have to put a photo to fulfill my part of the deal. I'll place it this weekend. ? 

 

 

Edited April 5, 2019 by jose

[jose]

After 1 hour voltage on 562r fall to 1.9Vdc.

[samsie]

This was completed an hour ago.  It worked though I did not do any measurement.  I tried it with my only planar Hifiman HE6.  The volume was a dummy.  I used a preamp.  I could not afford a decent volume control for individual headamps.

Edited April 15, 2019 by samsie

[A_Zero]

Could anyone repost the schematics? Have never been able to visit gilmore's website...

[jose]

Find "currentsource" here

I´m working on a F2J. It will be very interesting. I had not had any experience with this type of amplifier until now.

I don´t think that it´s a "definitive amplifier" (I'm in love with the balanced Dynahi) but as an alternative it's not bad for the planars.

 

[A_Zero]

9 minutes ago, jose said:

Find "currentsource" here

I´m working on a F2J. It will be very interesting. I had not had any experience with this type of amplifier until now.

I don´t think that it´s a "definitive amplifier" (I'm in love with the balanced Dynahi) but as an alternative it's not bad for the planars.

 

Thank you very much sir, thats one big treasure of schematics

[jose]

Just now, A_Zero said:

Thank you very much sir, thats one big treasure of schematics

You have to thank Dr. Gilmore and everyone who has worked on it.

[jose]

On 2/29/2016 at 10:39 AM, wink said:

More realistically 2.27/35 = 0.0649A = 64.9mA.

 

Please guys, could you explain this to me?

I understand that 2.27volt. goes through 50r. Why replace it with the impedance of the headset?

Gain selector is quite a hit. I'm enjoying it enough!!! 

F2J and the KG Transconductance Amp have a very similar behavior; they shine with impedances between 30r to 75r from there they lose a lot.

[jose]

I forget to hang some photos of this amplifier.

Sorry, I did not have any GRLV at that time ready.

 

 

[somerset]

I came across this amp and I'm wondering if this can run a pair of fullrange fostex horns (96db and 8 ohms min).  Apparently they thrive being current driven and aside from Pass F1/2, pickings are really slim. As my Chord Mojo2 can run them quite appreciably loud (from a battery no less). I'm looking at headphone amps.. Any advice appreciated!