Do It Yourself

Had a few transformers from ToroIDY with two 115V primarys I needed to serialize, unfortunately no markings of the phase. Hook'ed up one of the secondaries to a function generator, and serialized the two primaries. Having two free leads and two connected leads (CT) Measured the voltage V1 from CT to one lead, and V2 from CT to second lead. Finally measured the voltage V3 from lead to lead. If V1 + V2 = V3, then the two windings are in phase. If V1+V2 ≠ V3, the the two windings are out of phase. Are there an easier way of determine the phase of transformer windings?

Hey, I was thinking about using the 220 taps on the primary side here in the US in order to half the voltage on the secondary side of a transformer. Can anyone think of any reason not to do this?

Anyone ever try something like this? https://audioxpress.com/files/attachment/2685 I wanted to see if I could find something passive that would take an unbalanced signal from a preamp and convert it o a balanced output. Is this worth trying? Or would I damage the balanced amp?

Has anyone ever looked at, or used these On Semi parts? Look interesting to me. (Mouser part numbers below): 863-MPSW56RLRAG 863-MPSA56RLRAG 863-MPSW06RLRAG 863-MPSA06RLRAG The "W" devices are rated to 1W @ 25C in free air.

I'm sorta intrigued by this unit: anyone know much about it? Also, anyone heard the AVC TVC units from Diy HiFi (i.e. Django, etc.) 50/50% Permalloy Core Autoformer 28 step (Pair) | Diy HiFi Supply Of course there is the S&B, Sowter, and Jensen (and probably Lundahl) .. any others to consider? This would be used in conjunction with an active preamp. What is the general consensus of TVC used in this type of situation?

I could use some help with a problem I have in my father's amp. It is an integrated tube amp, Sonic Frontiers SFC-1. The amplifier has a "direct" toggle switch, which sends the signal directly from the RCA input to the volume pot,and then has 4 inputs which go through an elna selector switch and a balance control. When using "direct" nothing is wrong, but when using any of the other 4 inputs there is audible distortion in the music. I went through the tubes, checked and replaced each one with some older ones and they seem to be fine, the situation continued. I've inspected the solder joints in the rca's and the elna switch andthey seem ok. the balance control is i…

I need help putting together a simple TTL converter circuit to raise three DSD / SPDIF3 signals up to TTL level. I'm tapping the lines off a TI DSD1608. Here's what I have so far. Specifically, I was looking at a single TI SN74HCU04D for all three signals. Any recommendations on the cap here? I was thinking all surface mount here, but whatever the consensus is for the caps, I'm fine with. I'm thinking of adding a regulator as well nearby, like a National LP2985 5V regulator, or similar. Currently, these SPDIF3 lines won't leave the single box player, but perhaps down the line I'd route them to an external box via BNC cables. Either way, I'm assuming a single buffer…

http://cgi.ebay.com/OLD-Fluke-407DR-Plate-Filament-Rack-Tube-Power-Supply_W0QQitemZ160184703511QQihZ006QQcategoryZ58287QQssPageNameZWDVWQQrdZ1QQcmdZViewItem If you have room for this thing...

I am in need of a preamp with some gain and I was thinking about a DIY tube preamp. Doesn't need to have crazy high gain as the power amps will have voltage gain as well. Right now what looks attractive is the K&K Audio active output stage. The level 2 kit comes with most parts including the OPTs. Looks like a fairly good design to me? If not any other suggestions? Preferably something that is well documented.

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?

This is for use on my balanced beta22, the zobel networks described at amb`s beta22 site are: 22Ω 2W 5% metal oxide power resistor and 0.047

So I don't make mistakes in my latest build I was wondering what is reccomended most. Should I twist the AC power leads on a torroid being used in a DAC? Should I twist the DC power hookup wire that will go from the PSU to the DAC board? I'm assuming I should always twist the signal wires...

Twisted Pear Audio Looks like a new round of boards will be available for purchase this weekend. Get 'em now while you can.

I'm about to start fiddling with wires as I build up to making myself some cables (balanced interconnect and a balanced headphone amongst others). 26 awg spc solid core wire electrical insulating tape rather than heatshrink (I found a heatgun a bit expensive for learning) a hand drill for twisting the wire Is there an optimal number of turns per inch to twisted pair and starquad cable when used for balanced headphone based audio ? I am aware that cable capacitance can increase with density of wire present at a point (so less turns might be better) and that the common mode noise rejection will cancel interference only if it affects both wires equally (ergo mo…

a couple cool projects have popped up recently, one by Papa himself and one by John Curl's number one fan, Grey: http://www.diyaudio.com/forums/showthread.php?s=&threadid=120673 http://www.diyaudio.com/forums/showthread.php?postid=1484933#post1484933 Just figured someone around here might be interested!

So I've been looking at a bunch of tube/solid state hybrid dynamic amp schematics, and every one of them is some form of bad, or really bad. (one person/ex company in particular) Low voltage plate, capacitve coupling of a high impedance source into a low impedance, poor balance etc. There had to be a better way. true balanced input. dc coupling. low impedance output. no feedback. proper use of a tube (pure transconducance) etc so I came up with this, work in progress. 4 x 3 inches ubaltobaltubeschem.PDF

just got this for free from the good folks upstairs. nothing beats a free soldering iron (the one i have a cheap one from home depot) but is it any good? has a nice little slider for temperature control. cant find too much info on it online so i thought i would ask. the guy who runs the electrical engineering labs is cleaning house so is giving away a crapload of stuff (transformers/old drivers/test equipment/anything under the sun). i already called dibs on anything audio and surprisingly he hasnt had any requests for the stuff i put my name down for so should be nice. he used to work for bendix back in the day and has some 600 tubes in pristine condition he is t…

I met Per Lundahl at Capital Audio Fest last year, and in trying to figure out what I could use I'd have for Lundahl transformers I asked about winding something that can drive e-stats, planars, low impedance, speakers from separate taps. I had also just bought a bunch of 6336B dual triodes, so thought that might work. The transformers came and many months went by but finally rigged something up. Basically right now it's just 6336B with both triodes in parallel, running about 200mA with a B+ of 260V. There's an e-stat output that steps up, and also 50 ohm and 6 ohm outputs. The grid voltage is set by a bunch of 9V in series. The black box in the middle on top o…

Anyone interested in a Universal Signal Isolator shield for the Arduino DUE? http://www.dimdim.gr/arduino/universal-signal-isolator-shield-for-the-arduino-due/ Found this while looking up how to add a display to my dac. I'm looking to order some boards so I thought I would see if there is any interest here

9 years ago i started tinkering with the idea of a board to upgrade both of my SRD-7 to SRD-7 MkII, and then eventually a lot of stuff in my life went sideways and the project got shelved with a lot of other stuff. It did not work! it kind of worked. I screwed up something in the way the voltage multiplier was hooked up to the extent that there was only 26vac across the zener. I re-drew it yesterday. It's possible that aliexpress 1n4007 diodes were a factor. I'll use uf4007 sourced from mouser for the next revision. I know this shouldn't be hard. I'm kinda dumb for a smart guy. Sometimes i get a brain cramp. At the time, 9 years ago, my only high-bias stats we…

I have a few uses for a simple, regulated power PCB that supports a number of different ~25VA PCB mount transformers with a bit of filtering on each side of the transformer. I'm trying to nail down the schematic a bit and wanted to see if there was any advice out there

To all the owners of a transistor amplifier V3.0 from http://www.high-amp.de out there in the world. Here is a support how to update your amplifier to the version 4.0 that will be coming out soon. The items below are refered to the following schematic: http://high-amp.de/html/transistor_v3_schematics.html - replace the four resistors R07x and R08x with 51K/1W resistors to increase the current in the second stage to 4mA - replace the two resistors R11x with 200 ohm resistors to increase the current in the last stage to 15mA - replace the resistors R56, R57 by a constant voltage source as shown below (one per chanel) - If you are using the 2SC5466 in the last stage r…

Below is -=Germania=-'s handy work for your viewing pleasure. The unit is an opus dac with usb receiver and a 41hz amp 6 t-amp. The big pictures are of the power supply to the amp that is now making a ticking sound. The front LED is no longer being powered. There is also a low hum from the unit, but I can't tell which board it is coming from. I have a multimeter and soldering iron, so if theres something uncomplicated to try, I am game. I built my power conditioner, so I'm not a total noob, but I never learned how to read circuits. Biggie.

hi! i'm new here.. i'd like to ask for some help. diagnosis and repair.. i have a A4tech hu-200 usb headphone. now it only plays the right channel.. but before that happened i noticed that the audio is like panning from left to right til it could only be heard in the right. i researched about repairing headphones and all i saw is that the problem could be a loose wire or something similar but when i open my headphone there were no loose or broken wires. what could be the problem? and how do i fix it? i don't wanna send it to a repair shop cause i wanna see if i could repair it myself.

I'm thinking about using the 4 gang ALPS pot for my dynahi. I want to mount it on a pcb but I don't see any available so I thought if I took two epsilon 27 boards I could make one. The first board would fit the front, the second board looks like it would need the front trimmed off to fit the back section. The grounds are tied together on those boards so I'm not sure how that comes into play since I've never wired a pot for balanced audio before. How do you wire a volume pot for balanced audio and do you think this would work?