[soren_brix]

@soren_brix I actually have already purchased the article, just needed to ask questions about what I was reading. I have one more question, regarding the use of a trimmer pot: Do I want to use its center lead? Thanks for your help.

You might have spend a lot of money on parts and really, really wants to go through with this - however, you questions so far all points in the same direction: don't!

 

[Muffinhead]

You might have spend a lot of money on parts and really, really wants to go through with this - however, you questions so far all points in the same direction: don't!

I appreciate your concern. I'm a stubborn person, however, and will complete or attempt to complete this project by any means necessary. I'm no expert, as has bern stated many times, and would like to ask questions here, as dumb as they seem. I need not be lectured about my acknowledged lack of knowledge.

 

[JimL11]

I am sorry, you are right. I think he was referring to space charge within the plane in which the thin coating is laid down:



So I presume temperature, humidity and moisture are not enough to charge air surrounding that coating plane.

More humidity in the air can lower the ionization point, but Stax designs the phones so as not to have ionization regardless of atmospheric factors. The problem with ionization is that it produces sparks, which is not good for the health of the diaphragm.

 

[DJ The Rocket]

if you remove the grill of the L700 (the grill help greatly to create the illusion of forward sound) the sound-stage will be less forward and more to the sides of your head ... much more like traditional headphones with little increased details/depth too. But I prefer the sound with grill on bcz voices are projected forward and better bass (maybe)

I'm not sure what you mean by "grill." I'm looking at an L300 though, is this something unique to the higher models? Or do you mean that vertical strip of leather covering a fraction of the drivers?

I completed the O2 project.

That's awesome! Do you feel that the experience taught you useful lessons to apply to your bigger project? That was the reason I brought it up, after all, and if it wasn't good advice I'd like to understand where I went wrong

I know I personally had a list of new conceptual insights and improved practical techniques after my first PCB build.

 

[Muffinhead]

I'm not sure what you mean by "grill." I'm looking at an L300 though, is this something unique to the higher models? Or do you mean that vertical strip of leather covering a fraction of the drivers?



That's awesome! Do you feel that the experience taught you useful lessons to apply to your bigger project? That was the reason I brought it up, after all, and if it wasn't good advice I'd like to understand where I went wrong

I know I personally had a list of new conceptual insights and improved practical techniques after my first PCB build.

Yes, it was great advice to get the O2. The most important thing I learned was to look closely at which components have a polarity which needs to be paid attention to. It also taught me how to read resistor impedance values and better soldering skills in general. Much appreciated.

 

[ahmedie]

I'm not sure what you mean by "grill." I'm looking at an L300 though, is this something unique to the higher models? Or do you mean that vertical strip of leather covering a fraction of the drivers?

this is the grill picture im talking about, https://stax.theshop.jp/items/7561129,(i like the sound with grills though for forward image) Btw i have both l300 and l700. You can also swap left cover and attache to the right driver and vice versa which change the presentation for less width / more depth (I like this mod on l300 but not l700). I can post pictures of my moded L300 (damp back of driver with transparent foam similar to the one on older lamda ) or L700.

 

[Muffinhead]

OK, here's the MOSFET circuit I completed today. I would like to use two 9v in series to adjust the current-is this OK, or is the current from this source not sufficient for testing? I am aware of the long exposed leads and will cut or insulate them before installation in the chassis.

 

[DJ The Rocket]

Well, yes and no. The stators form a capacitor - two fixed plates in space, and the musical signal is imposed across them to cause the membrane to vibrate, so in that sense the capacitance is integral to it. But in terms of drive requirements, see below

Thanks for your (and everyone's) help! I wouldn't say I completely understand it yet, but getting there is going to take more effort than asking a question on a forum. I do understand it better than I did before, my mental picture has more detail and fewer fuzzy parts.

Boldly we barrel toward the next misunderstanding, right?

this is the grill picture im talking about, https://stax.theshop.jp/items/7561129,

Ah, somehow the ",(I" got stuck to the end of your URL but I got it off, yeah that's the part I thought. Google translates it as "Net Holder." I hadn't thought to try reversing my Net Holders, interesting idea

You might have spend a lot of money on parts and really, really wants to go through with this - however, you questions so far all points in the same direction: don't!

I can't speak for everyone, but I gave up trying to warn him off long ago. Way I see it, all that's left is what in other contexts is called "harm reduction"

 

[JimL11]

OK, here's the MOSFET circuit I completed today. I would like to use two 9v in series to adjust the current-is this OK, or is the current from this source not sufficient for testing? I am aware of the long exposed leads and will cut or insulate them before installation in the chassis.

That looks correct. Two 9V batteries in series should supply enough voltage and current to adjust the current sources, and you can connect a third 9 volt battery in series to confirm that the current does not change as you increase the voltage. I would put a 100 ohm 1% resistor in series with the batteries and measure the voltage across that to measure the current - you should get around 0.49 volts = 4.9 mA across that resistor when the current source is set correctly. Then if you like, you can measure the resistance of the resistor plus pot and substitute the closest 1% resistor to set the current permanently.

 

[Muffinhead]

That looks correct. Two 9V batteries in series should supply enough voltage and current to adjust the current sources, and you can connect a third 9 volt battery in series to confirm that the current does not change as you increase the voltage. I would put a 100 ohm 1% resistor in series with the batteries and measure the voltage across that to measure the current - you should get around 0.49 volts = 4.9 mA across that resistor when the current source is set correctly. Then if you like, you can measure the resistance of the resistor plus pot and substitute the closest 1% resistor to set the current permanently.

Thank you very much. Your article stated that you could use a 261 ohm resistor + 100 ohm trimmer pot instead of using a different resistor for each CCS; this is the option I took. So,does that mean that each CCS uses the pot + resistor combo? And one more pretty stupid question: I can't, for the life of me figure out how I'm going to attach the DN2450 assembly to the perfboard, and the perfboard to the heatsink. From what I've read, the 10m90s bears the brunt of the voltage coming from the B+ rail, so that means that the DN2450 doesn't generate a lot of heat. right? In that case, is thermal conductivity of the mounting surface a big issue? Again, much appreciation for your guidance.

 

[Muffinhead]

Thank you very much. Your article stated that you could use a 261 ohm resistor + 100 ohm trimmer pot instead of using a different resistor for each CCS; this is the option I took. So,does that mean that each CCS uses the pot + resistor combo? And one more pretty stupid question: I can't, for the life of me figure out how (or where) I'm going to attach the DN2450 assembly to the perfboard, and the perfboard to the heatsink. From what I've read, the 10m90s bears the brunt of the voltage coming from the B+ rail, so that means that the DN2450 doesn't generate a lot of heat. right? In that case, is thermal conductivity of the mounting surface a big issue? Again, much appreciation for your guidance.

 

[soren_brix]

10m90 goes to a proper heatsink, use nylon screws (not metal) and the Aavid 4170G alu oxi pad for mounting and thermal paste (regular white stuff and not anything else).
dn2540 doesn't need any additional heatsinking.
mount the 10m90 + resistors + DN2540 on a small piece of vero board (resistors on top with dn2540, and 10m90 underneath, mounted directly onto the sink, with its legs bend upwards to reach the vero board.
Vero board mounts onto the sink using standoffs. short wires from vero board to plate. wires needs to be rated for 400V.

 

[JimL11]

Thank you very much. Your article stated that you could use a 261 ohm resistor + 100 ohm trimmer pot instead of using a different resistor for each CCS; this is the option I took. So,does that mean that each CCS uses the pot + resistor combo? And one more pretty stupid question: I can't, for the life of me figure out how I'm going to attach the DN2450 assembly to the perfboard, and the perfboard to the heatsink. From what I've read, the 10m90s bears the brunt of the voltage coming from the B+ rail, so that means that the DN2450 doesn't generate a lot of heat. right? In that case, is thermal conductivity of the mounting surface a big issue? Again, much appreciation for your guidance.

Yes, each CCS needs a 261 ohm resistor plus trimmer pot. The DN2540 does not need additional heat sinking so it can just sit in the open. Because you soldered the gate resistors to the transistors, it becomes a little trickier to arrange, but OK. Here is one way to do it. The 10M90S and DN2540 will be next to each other, with the 10M90S on the left and the DN2540 on the right, at the edge of the perf-board - this allows the 10M90S to be attached to the heat sink. The DN2540 will be close to the heat-sink but not attached to it.

If you use perf-board it can be attached to the heat-sink using a couple small L brackets at each end with one screw into the heatsink and one screw through the perf-board.

First, bend the gate resistor on the DN2540 up until its distant lead is pointing in the opposite direction to the leads on the transistor. Then bend the distant lead back over so it is pointing in the same direction as the transistor leads. Now you can insert the distant end of that resistor along with the transistor leads into the perf-board at its edge

Next, bend the gate resistor on the 10M90S so that the resistor is lying across the transistor and pointing towards the DN2540. Insulate the distant lead of the resistor - an easy way to do this is strip some insulation from an insulated wire and slip it over the resistor lead. Insert the 10M90S into the edge of the perf-board next to the DN2540. Notice that the far end of the 10M90S gate resistor is close to the far right lead of the DN2540.

Now, you can solder the distant end of the 10M90S gate resistor to the far right lead of the DN2540 above the perf-board.

The 261 ohm resistor and trimmer pot can be inserted in the perf-board directly in front of the DN2540, then wire everything up on the underside of the board. I suggest you make a drawing of all the parts and draw in the connections before you proceed.

When everything is connected you should have two free leads - first, the middle lead of the 10M90s, which will go to the B+ lead of the plate resistor, and second, the lead where the gate resistor of the DN2540 gate resistor is soldered to the adjustment resistor and pot. That will go to the tube plate. You will solder wires to each of those. Use different color wires so you know which lead is which. When you are done you should have an assembled heat-sink with 8 wires, 4 of one color and 4 of another color, which will replace the 8 plate resistors you removed earlier.

 

[Muffinhead]

@JimL11 Thank you, that answers every possible remaining question I could have about the project. I'll finish it over the next couple of days and let you all know how it goes.

 

[SilverEars]

What is the difference normal KGSSHV and Carbon?