jose

Your policy about pre-orders seems to me quite logical and honest. I want to try one of your headphones. Will you do direct sales (through internet) or through suppliers?

I would like to think that yes ... I have it in my sights.

Happy Birthday!

They would be the first Grados to reach Mars

Offset around +-150mVdc and balance at 100mV in both channels. The resistive value (121R + 1K trimmer in parallel) after regulation is 79.9 Ohm in all channels. My amp passed from 18mA to 20mA BIAS. This works and I'm quite plaised. I could leave it like that but I'm thinking about how to do this mod something more "elegant" and at the same time I with this kind of trimmers but I dont´want to separate the pcb to heatsink because is a pain.

Different 121r and 1k trimmer in parallel. Ok, it's no nice but we haven't space on the PCB.

Nice Michael !!!! I am going to try the same Mod but changing 100r for 120r and add a trimmer of 1K in parallel. In theory the result should be "similar" but who knows. Without magic smoke, not can be glory ... I suppose

Thanks Michael!! Please, two sets for my if it´s possible.

The guy who sings the chorus is spectacular.

I guess you already had me in mind, right?

My amplifier was sounding about 5 hours continuously. I had no problem handling 18mA. Temperature with this heatsinks makes all measurements very stable. The body of the transistors was at about 40º after one hour and it remained in a range of about 40 ~ 45º all the time. I think it's right in choosing big heatsinks. As I mentioned, working with SE sources the amplifier goes perfectly, although with a balanced source the volume increases a little. I do not see anything wrong with modifying the BIAS. Maybe a trimpot could be added to future pcb´s ¿?. I will leave it at 18mA for the moment. What worries me a little is the offset. Although it´s stable (hardly varies ~ 0.7Vdc after being so long on) I don´t feel very comfortable with values of 14.5 / 9.22Vdc channel L and 13.76 / 11.88Vdc channel R maybe because I'm used to having levels close to 0Vdc.

Probably a minor work of Bruce but for me it has a very special meaning.

Thanks but my amps are very simple... besides this is a temporary wiring. It's all pretty chaotic. For the moment, I prefer to start with the values that Congo5 selected. Anyway, with these heatsinks, my amplifier stays moderately hot, so I rule out changing anything if it's not necessary.

I have not changed any value. I guess you mean R33 / 35 according to Dr. Gilmore's scheme ? Yes, 2K.

My CFA is already singing. Thanks to Kevin, Congo5 and Michael I´m using a SE source without problems (bridge "cold" channel to ground). My unicial assembly is a bit precarious but only because I wanted to check that everything works correctly. My "Mini BH PSU" to -407Vdc and + 404Vdc. Offset at the start with 14.5/9.22Vdc channel L and 13.76/11.88Vdc channel R. After one hour it is very similar on all channels. Balance 4Vdc and 2Vdc. I hope this is not worrisome. I am using "adequate" heatsinks ?. Temperature transistors after one hour of use is barely 40º. I guess that's why the offset remains so stable.

It reminds me of some of Fripp and Eno's songs.

I think so too. ♥️

Guys, yesterday I used my Shars Tap Holder with the CFA heatsink... incredible, in just 25 minutes I had finished screwing all the holes. All have been perfect !!!! Normally for this work I would need hours and surely some thread would be skewed. Great purchase and great discovery. Thank you!!!!!

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

I have to look at this but maybe with + rail of the GRVH (Split pcb´s) maybe I can get + 220Vdc

I´m not sure but I think that it´s not possible. Used a specific PSU is a better idea.

Maybe a GB?

Wow… descansa en Paz Luke

Yes, it is what I had understood. Interesting. It looks like it's the size of a SquareWave. Pcb´s should not be very expensive.