[Marco audio]

The parts look nicely done. Go for it!

Thanks for encouragements Chinsettawong,
I saw your beautifull pieces with wonderment: you're an artist !
I'm building now the spacers.
To follow...

 

[Marco audio]

I want to built the OTL tube amp too(in order to learn).
Due to an order error ,i have 4 6p7s tubes (instead g807 for my plasma speakers).
This tube can handle a 500v anode voltage.
So i wonder if i can use them for the output stage of the amplifier.
A 24Kohm anode resistor and around 550v at entrance.Grid bias -22.5v
Am I wrong ?Could it work ?
Regards

 

[chinsettawong]

Sorry, I can’t help you with the amp design. Maybe someone will shim in later.

 

[lkos98]

@Marco audio
Wow, 94x71 is equal to a circle 92 mm diameter. You should have amazing bass response. Please share it once you finish the phones.

 

[Marco audio]

@Marco audio
Wow, 94x71 is equal to a circle 92 mm diameter. You should have amazing bass response. Please share it once you finish the phones.

In fact i have designed my speakers with the step of the grid.
Now i'm starting to build the spacers with 0,8mm fr4 plate with one side coppered.
Mylar jig is builded.
I Have now 2um mylar film and Licron crystal.
Regards.

 

[Marco audio]

Hello,

Difference between stators load In the same speaker.

There is few differences between the both stators of the same speakers :
-spacers should be lightly different as well as grids sizes .
Conductive coat is on one side of diaphragm.
Theorically it goes loads différence :
how many Ohms could it have ?
please.

Regards.

 

[Ulfar4]

It is not about Ohms, it depends on capacity. You should get about 100pF to 150pF on headphones. When you have bigger active area, capacity will increase.

 

[Marco audio]

Thanks for reply.
You mind a différence of 50pf between both stators of the same speaker or 50pf for the both speakers of the headphones ?
My question was for one speaker and his both stators.

 

[Ulfar4]

It is for one speaker, stator to stator, but I thought about it as complete speaker with cable. Without cable it will be less than the 100pF I mentioned above.

 

[Marco audio]

It is for one speaker, stator to stator, but I thought about it as complete speaker with cable. Without cable it will be less than the 100pF I mentioned above.

Thanks a lot !
I understand now why there is an adjustable entrance voltage for each power stage tube on some schematics.
Regards

 

[Tjj226 Angel]

I want to built the OTL tube amp too(in order to learn).
Due to an order error ,i have 4 6p7s tubes (instead g807 for my plasma speakers).
This tube can handle a 500v anode voltage.
So i wonder if i can use them for the output stage of the amplifier.
A 24Kohm anode resistor and around 550v at entrance.Grid bias -22.5v
Am I wrong ?Could it work ?
Regards

If you want an OTL amp, then I highly recommend you triode strap the pentodes. Pentodes have a lot more noise than triodes do, so its not a great idea to use them in an OTL configuration.

Ideally I would recommend you just spend extra money and get proper low noise triodes. I would go so far as to put a few triodes in parallel to reduce the output noise even further.

If you are considering a simple OTL push pull amp with a bipolar PSU to directly drive your ESL headphones, then I would go buy a bunch of 6bq7a tubes. They are cheap as dirt, they sound great, and you can afford to parallel a few of them to keep the noise pretty darn low.

 

[Ulfar4]

I am using floor cleaner for coating but I found out that after few months or half of the year approximately, it is starting to go bad and I need to recoat membrane. I am thinking about buying Licron spray. Will this spray do the trick for long term stability? And I am able to purchase LICRON 1756-8S, but I do not know if it is the right type.

 

[Marco audio]

I am using floor cleaner for coating but I found out that after few months or half of the year approximately, it is starting to go bad and I need to recoat membrane. I am thinking about buying Licron spray. Will this spray do the trick for long term stability? And I am able to purchase LICRON 1756-8S, but I do not know if it is the right type.

Hello Ulfar4,
Thanks for your reply.
I have readed In post on facebook group that Licron is not so good:
Performances decrease quickly.
Expérimentéd diyers use elvamid and colloïdal graphit.
Oh a propos i have a Pdf from Philippe Higara. Hé use colloïdal graphit and vynil cleaner(near glue for wood?).see p116 or 8/11.
Regards

 

[Marco audio]

PS:The amplifier from Philippe Higara

 

[Azrael3000]

It's been a while since I have been on this thread but for both me and my friend Benny life happened (in many good ways fortunately) and so we did not have time to start with Mk2 of both our headphones and the guide we wrote. I have started to educate myself in electronics and have now reached a stage where I start thinking about an amplifier build for the old and to be built headphones. I don't want to make it too complicated as I'm still learning, so the two options that seem most sensible to me right now are the ES HPA-1 (or 2) from Tubecad or as a solid state alternative the CFA from Kevin Gilmore.
Does anybody here have any experience with these amps in terms of difficulty to build, performance or even a comparison between the two? Obviously tube and solid state are going to be different, so any general recommendations are welcome too or even name dropping of other amps that would be suitable candidates.

Thanks,
Arno