Thanks dsavitsk, helps a lot.

Cool My preference obviously goes to the string of LEDs, what's not to like about much more lighting ?   I didn't pay attention when I picked the schematic from nutshellhifi. I didn't mean doing someting ultrapathstyle, rather having the primary of the output transformer going from one...

Thank you both for your answers.   By biasing current I meant the current going through the tube, but I admit that the question was ambiguous. I am still stuck with calculating it ; if I say Vbe of Q3/Q4 is around 0.7V and forward voltage of D12/D13 around 1.8V I get I_bias=(1.8-1.1)/402 since...

Hi   I have been looking at the schematic for the Torpedo (quick link : http://www.diyforums.org/Torpedo/schem/TORPEDOschem.gif)  and there are a few things I can't figure out. First is the bias current : is it only 2 or 3 mA ?  Second is the biasing method : does it serve a purpose to have...

Does anyone other than me have issues with the headband size adjustment ? I feel it is to loose, which means that I can't properly adjust it to the size of my head, when I choose a step that fits, it eventually gives up and the headband gets to large. Is it  a natural thing for the hd-25 or is...

Thanks 00940 but I am still looking to build something around the parafeed topology

Buy a pair of cheap transformers from radioshack and manage the wire so that if you fail hard (everybody does from time to time) no loose wire will go close to your DAP. The transformers themselves are not very good but they will let you see if the Cmoy is working or not.   While you are at...

They look good and would be perfect for the job but shipping only is twice or three times the price of a pair so it looks like a dead end ... I think I will be trying a pair of cheap toroids from Mouser.

Quick question : are the edcors xsm10K-600 built to be used in SET amps with DC accros the primary ?

Look for a hackerspace around your place ...

Wait for dsavitsk   In the meantime you can have a look there : http://www.head-fi.org/t/625157/lespressivo-tube-amp I understand we have basically the same goal ...

So what does the output stage look like ? I guess a white cathode follower or a srpp stage is out of the way now ... Simple cathode follower with two 6H30 per side ? edit : the heater-cathode voltage breakdown is pretty high with the 6H30, I may be wrong.

I am pretty sur you can pull off a gain stage + white cathode follower  tube amp using only 3 12AU7. But if you feel too limited by these tubes, you only have to buy other types (lots of very cheap options on ebay) and play around with these. I don't know how tight your budget is, but unless you...

Quote: I don't really understand this. The way I see it, he is building a capacitance multiplier. Helps filtering and adds a little bit of delay for the high voltage to rise more smoothly, no regulation. It wouldn't be very expensive to implement a simple regulation (just as you described)...

Quote:   From headwize. This is supposed to be the "reverse-engineered version of the EarMax". Remember that you will also need two heater supplies, but it is already the cas with your first schematic ; on the picture above it seems that they are left floating, doesn't seem like the...

Quote: I guess you want a lot of space between the conductors and thinner wires in order to reduce the cable's capacitance. I don't know how stax does it. Another option is to use a spare cable from koss, they are quite cheap.   BTW  you are not supposed to match the capacitance of...

You should find graphite pretty much anywhere. It is used to lubrificate doorknobs and is not expensive at all (~5$). Maybe grinding pencil leads would work, but you should be careful not letting bigger bits go through.   Quote: What you have to worry about is not resistance. Most...

Quote: I have read another time the way you put the diaphragm's movment into equation, and I still don't see how you can account for coating both sides of the diaphragm. The only change it would induce is a better symmetry but that is 5µm of diaphragm thickness regarding to the 500µm of DS...

Well yes but the parameter that you can easily control and impose to the headphone is not the charge, it is the voltage. You have to see an electrostatic speaker as a capacitor, but since the diaphragm is mobile, the capacity is not constant. Once you have imposed the voltage, you can deduce the...

Quote: The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.

Quote: No I don't. It would be a balanced amp with RCA inputs and 6,35 jack output   I forgot to look at Edcor's, thank you very much. And they can provide for every iron needed in this project.

I have been looking at the balanced version of the l'espressivo ( as attempted by fallen angel there ) but I am not too sure what input transformer should be used. It has to be cheap from input to output, and seeing what options I have retained for the rest of the build, the input transformers...

That's funny you ask, I spent half an hour worrying whether I screwed up my last cell, then I realized the diaphragm wasn't electrically connected to the spacer. So I put a tiny amount of solder on the other stator, the one on which the diaphragme isn't glued on, so this blob of solder insure...

I saved your picture with the uhu por tube a while back but didn't remember it until now ... Have you tried the two other type of glue I mentionned as well ?

I have a question about the type of glue that can be used to attach the diaphragm on the stator. I have been using epoxy glue but it is hard to do something clean. I was thinking of trying super glue, which is more liquid but I am not sure if it is a good idea. Any input ?   Quote: I...