Do It Yourself

As Luvdunhill has a limit of 100 total for his mini-GB, and the the count was well above 100 not counting myself and luvdunhill, I've got a quote from Trendsetter at 5USD/ea, at minimum of 100, I've decided to organize a GB for those who still wants the LSK389B at 5USD/each, state your interest here At this point in time there are almost 100. Please be aware that the GB started as for SOIC-8 package alone. I have added the TO-71 to the spreadsheet. 20160120: GROUP BUY CLOSED

A few of us over at another thread started by Blueman2 are contemplating getting SRX Plus PCBs fabricated. See this thread: http://www.head-case.org/forums/topic/12445-plan-to-build-srx-where-to-find-bom-boards/ Discussion of the SRX Plus design can be found here: http://www.head-case.org/forums/topic/11996-srx-revisited/ I've checked with PCBNET and we can get the cost the amp board to $25 if we order at least 15 boards. The board will be 2mm thick with 3 oz copper, the board size is 9.35" x 6.85" ( 2 channels on one board ). Kevin has recently updated the board with teardrops enabled. We have not decided on the PS to use yet. The SRX Plus needs a +/- 340VDC a…

I have a pair of 2n5457/5458 JFETs on a small board as part of a bias scheme for a 12AX7. The circuit also has a 9v battery. I cannot get the voltage dialed down, so I checked the JFETs. The resistance from gate to source (and gate to drain) read the same in both directions: roughly 1k ohm. These are dead, aren't they?

I was not really planning on going into work next week, but this has changed my mind. http://gilmore.chem....n.edu/ebony.jpg 1500 grams, 8 x 2.5 x 3.5 inches about 50 years old.

AKM post a pic, but still no details...

I was looking for sth DC coupled hybrid power amp for desktop speaker with no caps or transformers on either input or output. While searching on google, I wanted to find jfet/tube differential, tube voltage gain, MOSFET/BJT current gain design. Then I find this. http://tavishdesign.com/pages/direct-coupled-tube-headphone-amp any opinion? Though there's a cap on the input. Any other SE or balanced configuration will be welcome.

GROUP BUY CLOSED! 4. november 2015 Group buy for Mundorf caps (started in the Carbon GB thread by MWL168) https://docs.google.com/spreadsheets/d/1GWDWwLfsIDtwn1HB-x76lS6WyWwLd5lwsORFKiUuuEQ/edit#gid=2024111922 The amounts has been locked, and participants requested to state their location: country/state/postal, in order to estimate shipping costs. Estimated delivery is 43 for the lot and 46 for the remainder. Working on getting on delivery week. /20150916 Update: "680uF caps are comming 23/10 (according to FTCap). As soon as I have got those I'll post pics, and start shipping" 17/10-2015.

Hi Everyone, First of all, I'd like to thank you guys for all of the information you have posted on this site. Without all of this, I would probably be screwed, and not able to find enough information on how to make a Stax amp. I have been wanting a sizable upgrade from my pair of HD 595s and after getting the Fidelio X2s which I wasn't too impressed with, have decided to go all the way and get the STAX SR-407 . I decided that I would also like to take this as a learning exercise and build my own amp. I've built a Millet SS Hybrid before, and know my way around electronics a bit, although probably not at these voltages. I have been doing some research over this past …

Group buy from PCBNet (same as Carbon and Circlotron Group Buy) for boards > 40. State your interest here A table and a modular graphic for easier overview of the various Golden Reference PSU boards and their function: The color scheme is the same used in the modular picture below. Options, each representing a full PSU everything needed for an amp (in the spreadsheet one can choose either): Option 1: Contains HV+/-, LV+/- and PRO BIAS. Option 2: As Option 1, but “Split” into two separate boards, making mounting more versatile. (Skinny and FAT contains the same, but Skinny is rectangular shape wheres FAT is sqarish) Option 3: Separ…

GROUP BUY CLOSED 4. NOVEMBER 2015 For gauging interest. This GB is intended to be add-on to the MWL168 Carbon Group Buy for anyone interested in building a Circlotron. In addition to a full Carbon, two dual HV900 boards (circlotronhvpowerdualnewer2.ZIP) and two output & driver boards (kgsshvcarboncirclotrondriverv2.ZIP/kgsshvcarboncirclotron.ZIP) are needed. Currently investigating a quote form PCBNet for: circlotronhvpowerdualnewer2.ZIPkgsshvcarboncirclotron.ZIPkgsshvcarboncirclotrondriverv2.ZIPFurthermore FTCaps has been asked for delivery of the 470uF/550V caps required by the HV900 supply. The main difference between the 680uF/550V(76mm) cap and the 470uF/550V(6…

I've decided to get serious about learning electronics. Tangent suggests this: The Art of Electronics 2/eby Paul Horowitz and Winfield Hill Cambridge University Press, 1989 1125 pages, hardcover ISBN 0-521-37095-7 Would you agree with this or would you suggest something else? I also plan on getting the Tube Amp text that Birgir recommends. I just need to find it again someplace in the DIY threads. Edit: Would it be "Valve Amplifiers, 4th Ed" by Morgan Jones Birgir? Or maybe "Building Valve Amplifiers" also by Morgan Jones?

Hopefully I'm at the right place this time. I want to build a kevin gilmore blue hawaii amp. As a starting point I found the original http://headwize.com/?page_id=751 and the more recent http://gilmore.chem.northwestern.edu/BlueHawaii-T2-Servo-v1-2.zip (needs LTSpice). Is there a recent version without servo, with PCB's and all that? CCS is yet partly diskussed, has someone experiance with "mu follower Output" to decouple the complex loads partly from the tubes (see schematic)? What about a PS if no 500V pnp is found? From the PSRR viewpoint I'd start with the concept: "care about higher harmonics, PSRR can start to decrease at a cut-off in the 1 kHz region. And: …

GROUP BUY CLOSED 13/10-2015 Probing interest for doing GB on EL34(6CA7) NOS tubes. EL34(6CA7) XF2 MINIWATT NOS MADE BY MULLARD BLACKBURN UK Matched QuadsMade in 1966-68, at Mullard, Blackburn UKThe code on the tube is xf2 B7L3 showing this is manufactored by Mullard.Tubes has been tested on an Avo 163, and matched in quads. Price: 147USD/tube (depending on the exchange rate) ....we may obtain a small discount if reaching 40 in total The supplier guarantee that the tubes are original and is able to exchange a tube that turns out to be bad with a similar xf2 Mullard as he have several in stock. Show your interest in the GB sheet: https://docs.google.com/spreadsheets/d…

Hey guys, I finally found a good home in a small space for the Moth Cicadas I purchased many moons ago, and the room is conducive enough that I can really notice a bit of variance in the drivers. I have a set of unused spare drivers I'd like to sub in, to see if they are more to my liking. The only trouble is, I have no clue how to remove the old drivers. The cicada enclosure is ported, but the port is too small to fit a hand in, so I can't push the driver out from the back. It fits in the cabinet pretty snugly, so I don't have enough room to fit a spudger in around the edge and pry it up. Furthermore, being paper cones, I run the risk of damaging the old driver is I …

We're doing a quick moving T2 board set group buy; there are two members and we have a quote for two more (but will go ahead regardless). Specs are ... FR4Blue solder MaskWhite silkscreen2.36 mm thicknessENIG3 oz cuIPC-class 2100% e-TestedThe buy consists of a set of the full sized boards; one power supply and one amplifier board, $225 for the set + shipping and PayPal fees. Post interest here and we will close the buy in one week. If we have more then 4 participants the price will be lower.

Maybe keeping such things in one place will prove helpful? Maybe not. Anyway, to get the ball rolling, does anyone have a technique for removing a snapped off 4-40 tap from extruded aluminum side rails? Maybe the sort of kit one uses for removing stripped screws would work, but there is no head, essentially. Any other thoughts?

Hey everyone, I am in the process of developing a headphone for the Brazilian market, and thought I could use some help of the many knowledgeable people here, especially regarding the acoustics. Some background info on it: it's not going to be a high-end headphone, but one that has style, nicer choice of materials and decent sound quality, compatible with the $150-200 price that we hope to sell it for when it's done. I think something like an M50 but more stylish and with better materials would be a good analogy for what we're trying to achieve. I'm not sure it's possible, but that's our goal. The problem is that we're just a group of 4 people, with no enginee…

Yet Another Group Buy: Keithley 2015 THD Multimeter Except I won't participate as I have one already. The person I bought it from (in Korea) has many more for sale. Shipping is separate, so presumably you could buy them in lot and have them shipped individually to everybody from the source, pretty convienant. Pricing: (Used and functional units) more than 3 : USD $270 eachmore than 5 : USD $250 eachmore than 10 : USD $220 each It needs a central person to manage the money and information. If there is interest in a Group Buy and a leader who wants to take it, I'll forward the contact information. Please indicate your interest (how many) and whether you'd be willing to l…

I have a Quattro I and II with different issues, appreciate anybody who has repaired CDP's. I haven't opened these up yet, doing some research first. Quattro I. Has tracking issue. Has trouble tracking some disks randomly (some 20% of the time) Quattro II. Sticking/opening drawer issue. Possible to replace the drawer mechanism? Any replacement drawer pointers? Thanks much -

so this has been kicking around for a while, decided to publish. take my ubaltobal converter, cut it in half, and then take the top piece, replace the input transistor with a tube... high impedance input... DC coupled, no negative feedback, less than .01% thd, 10db gain... just add a high power bipolar output buffer, and cheap tube hybrid with lots of plankton. work in progress http://gilmore.chem.northwestern.edu/tubehybrid.pdf 100 volt power supply real simple with TI TL783 high voltage regulator +/-30 supplies with lm317/lm337 with boosters cheap!

I need a caliper for my guitar experimentation. Is there a better value out there than this one? I see this one on Amazon -- any good?

Hi: I just placed an order to have 10 sets of KGST boards made. A few of them are already spoken for but I should have 5 sets available to those interested. Here are some details: 1. The amp board is KGST6S4CASCODE (120mm x 135mm), the PSU is KGBHULTRAMINPSV4 (105mm x 134mm). 2. The boards are all 2mm thickness, 2oz copper, green silkscreen with white lettering. I wanted the thicker board that can better sustain the mounting and dismounting of the tubes. 3. I am using a PCB fab house in Taiwan which was recommended to me but I have no prior experience with them. 4. JimL has traced the cascode CCS part of the KGS…

I was inspired by Frank Cooter's PTP wiring amps he took to the LA meet. So inspired in fact, that I was thinking on building Kevin's KGTT. Besides him and Kerry (and probably Birgir), is there anybody out there who has built it and could post pics of their builds? My first clumsy attempt at a layout looks bad and it won't improve until I get all the components and have an idea of their size and shape. Hopefully it was done right A wood case, which I have never done, also sounds interesting. KGTT Layout a.pdf

I have have an old Dynalo power supply that I never got working properly, but I'll make another attempt. It's headamp.com PCB layout and I've used the parts list that was suggested at that time, except for the 5 uF caps. The suggest 5 uF caps were Epassives MKS4475J63-6, but I don't think these are available anymore. Instead I used Solen caps. Maybe that was the problem. Anyone here built the Dynalo power supply and could share a parts list? In particular, info on the 5 uF caps would be helpful. I'll also try some high slew rate caps. Digi-Key has Cornell Dubilier 940C6W4P7K-F with a slew rate of 105 V/us. These are quite large and won't fit the board properly, so thi…

http://nervenet.info/HT_delay/ I bought 2 of these to delay the HV startup of the megatron, I'll let you guys know how they turn out. Seems like a pretty nice drop-in