Do It Yourself

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.

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 -

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…

Now, Kerry is currently about to test the latest revision of the Kevin Gilmore Digital Attenuator, and since a few people have asked for a Group Buy we hereby probe the interest. Kerry is mostly inclined for the 50k version. Please put your request into the referenced Google spreadsheet. The information in the sheet in rgrds to price is from the former group buy and only to give an idea of where we might end with this group buy. As last time we will investigate cost of fully assembled boards as well as bare boards (with stencil) if people wants to DIY. https://docs.google.com/spreadsheets/d/131vk972PEIm-J4r5IbZT7IP7CAqoMfP4j0RfE0J0xeM/edit?usp=sharing Let me kno…

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?

I'm happy to report that the goldenreference low voltage dual power supply works as designed, and tests less than 1 microvolt of noise. Going to have to take it to work and put it in a screen room to really measure the noise. http://gilmore.chem.northwestern.edu/goldenreferencedual.jpg however there is one silkscreen error seen by the extra + near the 47uf cap on the right side. I will update the files shortly. All 4 of the 47uf caps need to have their plus sides pointing to the left. very happy with this

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…

Hope you guys don't mind, but I'm taking the liberty to collect some info, links etc. here. 900V floating supplies 350V/us the cole slew (couldn't resist) seems to be happening in bits and pieces in multiple threads on multiple forums and there are some implementation issues which seem to be worth discussing...namely fitting all of this somewhat daunting amplifier into one case. I guess at some point Kevin decided to split the input and output stages- output board output schematic The output stage features the floating supply floating supply fboard floating supply schematic the input/driver board As of today the aim is to fit this all in …

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

EDIT 8/4: attach updated GB details and remov outdated chart EDIT 7/31: attach updated GB details and remov outdated chart EDIT 7/27: attach GB details and remov outdated chart EDIT 7/23: attach PCB cost quotes and limit first time poster to 4 set of amp boards max. EDIT 7/19: proposing use of HV Carbon V5 board to replace both V2 and V3 boards. See posting # 190. EDIT 7/13: attach snapshot of final order entries and board count. EDIT 7/12: This GB is officially closed as of 7/12/2015. Due to the changes Kevin made to the PS boards, it'll take a few more days for these boards to be checked before I officially request quotes from the …

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 …

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…

What's the polarity of the Turbulent Labs driver? Is the green dot + or - ?

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…

There seems to be some consensus on the voltage requirements for electrostatic headphone amps. Nearly all of the commercially available designs put out between 1000 and 1600 volts peak-to-peak, a range of about 4 dB. The legendary Stax SRM-T2 was specified to put out a bit more, close to 1800 volts peak-to-peak, which is 1 dB higher. This would be equivalent to almost all loudspeaker amplifiers putting out between 50 and 125 watts, with the T2 being like a 160 watt amplifier. However, there hasn’t been much discussion on the current demands for electrostatic headphone amps. Output stage currents in commercial amplifiers have run between 2 mA/channel (Koss ES950) a…

Yet Another XLR Question... Building my first balanced amp, some connection questions: What do you do with the shield? Reading the RANE app notes seems not appropriate for parts of this, since I am using 4-pin XLR, and the 3-pin standard has pin 1 as ground. I am reworking the previous 4-conductore rewiring my phones right now, and chopped the previously wired 1/4" plug cable part way to wire in a 4-pin female/4-pin male (the male will be the main phone connector into a 4-pin female on the amp), turning this cable portion into an adapter for when I want to use the phones from an SE amp. The main cable terminates at the phones in a 4-pin mini XLR, in which the …

never mind

I've got a couple normal bias Staxen I'd like to build an amp for, any ideas for any simple mods to make a normal bias KGST? Edit: apologies if this is a simple mod, I've done searches but what comes up is for going the other direction (normal->pro)

Staxen amps (at least the Mafia versions) use either el34 or 6S4 (with the Megatron including some 12's ...) I sold my tube tester years ago after getting out of SET's and such. What do you all think about testing these tubes? Is there a simple test rig, perhaps even 'in circuit' we can use to test the tubes without having to deal with a full blown tester?

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'd like to call into question some do's and don't I've heard about building Stax amps. I'm an engineer who works on scientific instrumentation and have heard a few things I don't understand based on my experience, so thought it's worth a discussion here. Please correct me if my thoughts on these issues is incorrect, from an engineering perspective. High Voltage resistors are necessary In general HV boutique resistors are really only needed when there’s a large differential voltage. Let's take a high quality but not HV resistor, the KOA Speer which range from 250V-1kV working voltage http://www.koaspeer.com/catimages/Products/MF-MFS-RK/MF-MFS-RK.pdf Take…

I ordered some of those teflon 9 pin sockets off the eBay user many here have used. They look fine but I've not used 9 pin teflon before, at any rate getting a tube in one is extremely difficult. I can remove an individual pin and put it on pretty well, but leveraging all nine into the socket is a nightmare, I can't imagine trying this with a soldered socket. At least when unsoldered the pins have a little play to align themselves. Other experience? Do I actually need to pull all the pins, try to use and pre stretch them before use? Ugh ...

Hi: I am organizing a mini group buy of HGSSHV PCB boards. I intend to move very fast so please read this post carefully if you are interested. I'll be using the kgsshvampv16mini.zip for the amp boards and kgsshvpsminifinalstn9360.zip for the PSU boards. The amp boards are the one-board-per-channel, off-board heatsink version. Both amp and PSU boards have provisions for current production parts. See here for the Gerber files and the KGSSHV thread for more information. I plan to use SeeedStudio to fabricate the PCB boards. The boards will be 2 layer, 1.6mm thickness, 2oz copper, HASL surface finish and standard green color PCB. Each set of the boards includes …

Does anybody have a source? All I see so far is chassis mount.

Hi all, As part of my home theater build, have decided to go for 3 way actives for front LCR… so, need to build 9 power amps for fronts and 8 amps for surrounds… to pair up with my Sherbourn PT-7020A pre/pro. I needed something as easy, but more powerful. This is when I and my friend John found the datasheet of TDA7293. This IC can run up to 100V, low distortion, and can easily be paralleled. Having built single chip amp and extensive listening TDA7293 is my favorites for IC power amp applications. I have been looking for a source of PCBs using parallel TDA7293s… there are not many out there that you can buy. We then decided to do our own PCB. Our schematic is almost…