luvdunhill

Here are the resistor lines I'm currently considering. Any opinions on which might be the lower noise and lower distortion resistors? http://www.irctt.com/pdf_files/PFC-COM.pdf http://www.farnell.com/datasheets/3698.pdf http://www.farnell.com/datasheets/43145.pdf By the way, this statement is more or less "Due to special technology used to produce tight tolerance, low TCR at high values the RP73 resistor is not individually part marked"

yay! my jig shipped from front panel express, so I may send that down your way soon as well, if you don't mind. Do you happen to have 3.5mm and 4.5mm drill bits? oh, when placing the devices on the heat sink, you'll want to place them so the long side of the board is oriented along the long side of the heat sink. You can center them, or actually mount the devices an inch or two down from center. This seems to work better in my experience and thermal simulations. I cannot wait to see them mounted with stand offs and what not. Also, those orangish Bergquist pads I sent are decently hearty, but try not to torque down and untorque the devices too many times. If a tear or some other sort of rip occurs in the pads, it will be bad news ... things will burn and you'll be unhappy. So, just treat them as fragile and try not to modify things too much once they get situated. Once the devices heat up, then they will sorta melt and form to the heat sinks. You can lightly sand the semiconductors (!) and the heat sinks as well before mounting the devices. I use 600 grit sandpaper. After your done sanding, clean the area to make sure no aluminum shards are hanging around.

I'd recommend prototyping with the actual passive parts that are going to be provided in the kit. So, it would be helpful to have a BOM I think. I believe both you and Jacob may be working on one?

looks great Steve! The thermistors should be placed as close to the devices as you can. I wouldn't worry about the heat shrink myself, except on perhaps the thermistors. Here's how NP did it: yup, no stinking capacitors in the F5 Does this mean my package arrived?

I'd assume it is, because one can build a ground channel. 6 channel beta22 buffer FTW!

I sent something else down your way instead

serious fracking hail outside right now. golf ball sized at least!

they will return the headphone with the Koss cable. From their standpoint, it is damaged and requires repair.

Hey, I was wondering if anyone might know of other attenuation curves, other than the standard log? What I'm thinking of is something that uses multiple logarithmic slopes, but I cannot really expect this to be a novel idea on my part. I have an idea that I'm working out, but was wondering if there was anyone else that has gone down this path? My one requirement is constant input impedance My second question has to do with SMD resistors. I'm looking at the Vishay Dale TNPW and Susumu RG/RGH (due to vanishingly low tempco values), but was wondering if there were other lines out there you guys might be aware of. I'm focusing on thin film resistors at the moment (unless there is a reason I shouldn't?). My requirements are <1% accuracy and a large number of values under 1K and the ability to buy in quantities <= 10 or so. The large number of < 1K values requirement is probably the most stringent. Anyways, any recommendations here? Any other resistor lines that I should consider?

ooh looks nice!!! good job! I believe there is an error in the schematic posted at Headwize?

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wait, the resistors got hot... ya.... I mean, how hot did the heat sinks on the psu get

try to stick that resistor we were playing with on the end of it for a while and see how it goes...

ummm.. that will be interesting.................

well, 1001 is another way to say 1K. 1002 would be 10K 1003 would be 100K and 1004 is 1M and 2201 would be 2.2K (see the pattern?) I think you might have both CMF55 and RN55 resistors perhaps ("commercial" and "mil-spec" resistors, respectively)? I'm not really sure myself ... they could be older resistors that use this different naming convention. Anyways, sorry I should have caught this based on your previous PM.

not directly related, but I'm messing around with my first input transformer tonite for single-ended to balanced conversion and balanced input isolation. I like what I hear so far, much better sounding than the IC solutions I've played with. I'll report back once I get the Sowters in house (I have a pair of Cinemag on loan). I'm interested in seeing if the center tap on the Sowters provides any benefit over the pair of resistors after the Cinemags. edit: one note so far, seems the input impedance really needs to be < 600 ohms. So, I'll throw that out there as the one constraint I've seen so far.

heh... I'll be a bit of a tease.. try measuring them with your meter and tell me what you get

er, 100 ohms? I don't think there are any in the circuit. Ya mean the 10 ohm striped resistors?

Sorry Steve... I forgot to talk about mounting those. In general, I'd recommend leaving some leg on top of the board, meaning not to squash them down close to the board. The reason being that you want to keep these things cool. Most people press them down thinking that they are keeping the signal path short or something. If I would have remembered to mention this to you, you could just have clipped them off of the top of the board and easily removed the legs and then remounted them. I usually leave ~0.25"-0.5" or so on top of the board, and when I'm feeling fancy put a bit of small teflon tube around the legs to protect them from accidental bendage. I'd try what Colin recommended, as that's what I do. It seems counter intuitive, but adding solder usually makes board rework easier. So, add a lot of solder, then work the tip (actually, more like the side of the tip, as you have more contact area this way) of the iron so it comes in contact with all three leads (if possible), or at minimum the solder pools. Play with aligning the iron this way before you turn it on, so you get an idea of the angle needed. Then once you've heated things up, reach around and pull the device out from the other side of the board with your fingers. Then clean up the holes with the solder-wick. The trick with the solder sucker is that once you heat the solder up, you have to quickly put it down on top of the solder pool and pull the trigger. It takes a bit of coordination to do. What I do is put one edge on the board and then use this contact point like a pivot and then once the solder is heated up, pivot down so as much of the nozzle is on the joint, hit the button and then remove it from the board... heh, pretty hard to describe. In short, it's harder than it seems

A pair of custom Sowter input transformers.

Is this a pretty decent deal?

seems to be much, much faster. I can definitely notice an improvement.

with all due respect, this conversation doesn't belong in a intro to DIY thread. I'd excise it if I could. This is way down in the weeds.. you new guys need to get your hands dirty and start to form your own opinions on what makes a difference

not trying to start anything, really.. but.. would you say these differences are relatively similar to how Senn lovers perceive differences between the HD-650 and HD-600, i.e. much much closer than they are different?

Steve: I'm sorta out of commission until later today, hopefully I'll survive some fireworks at pabbi1's house.... I'll give you a ring when I'm on the road back to Austin. With regard to IEC w/fuse and power switch, new it's hard to find something under $10 or so. One option is the below surplus part, which also includes a EMI/RFI filter... kinda like an integrated power conditioner. Since you have some mad square hole cutting skills, you could go this route. I've purchased several of these in the past: DELTA LINE EMI FILTER 6 AMP 06AK2D Lightly Used - eBay (item 330084141165 end time Jan-31-09 10:03:28 PST) Problem is, shipping nails you on these, unless you get 3 or so. The deal is, new these are probably >$25 each when purchased new. Anyways, this is one option. I'm sure others around here will have some good choices. If you like the one I used on your Pearl, it is Digikey part 486-1084-ND for $10.01. The deal with this, is it uses dual fuses. This is easily fixed with some solder, or actually using two fuses. A single fuse version of this would be more suitable in some senses.