Do It Yourself

I built my original Dynahi 8 years ago and I'm going to re-case it to match my other builds and to fix some hum because the transformer is in the same case. I built a stereo version with two one channel boards powered by one PSU. I do not remember how I arrived at the value of the transformer I have now but I think it's 160 VA. The original BOM for the PSU says 250VA. Should I go up to the 250 VA spec'd in the BOM? Or is the 160 VA enough? I was thinking of trying to reduce the size of the transformer because of the hum but now I see I may have undersized it.

I'm building a Xono clone. I need to match 2SK170 JFETs and BC550 BJTs. I'm new to transistor matching - Google has left me a bit confused with the amount of "suggestions". Any clues as to the best / most convenient method, hopefully with a link to a tutorial?

Aside from Alps RK-50, are there any quality quad potentiometers? I'm just curious if there are any others out there.

Looks Like I'm gonna have to have a dig around in there to see if I can tell what's wrong and try to fix it. I hope it's simple like the jack connection. I'll pop it open and post some gratuitous pics in a bit...

Standalone HDCD decoder? digital in and out, nothing fancy. PMD100 chip inside. Any thoughts? Maybe even an upsampler too as another function...

so pars posted this. http://www.diyaudio.com/forums/group-buys/315474-pure-tube-es9038pro-9028-9018-akm.html#post5259820 all sorts of wrong. lets start with the fact that current output D/A converters really like driving a zero impedance. 27 ohms is not a zero impedance. So with +/-1.2ma you get +/-32mv and then you use the tube to amplify the crap out of it. Nope, definitely not the way to do this. All sorts of noise etc... a while back there was bakoon and audio-gd pointing fingers at each other as to who designed satri and when. so here is the satri version 4 circuit satriic.PDF and here is how audio-gd turns it into both the I/v converter…

I'm thinking of having some of the golden reference, dynalo, and alps quad pot boards made. The place I was thinking of using was seeedstudio.com Is there a better place for small runs? Their least expensive option is 1mm thickness, 1oz copper in green. Are those specs good enough?

Anyone got a black neutrix 4-pin xlr NCMX they can spare to send me? Cheers Pete

What can I use to get rid of nasty sticker/tape goo residue without harming a nice surface? The item in question is the VAC-1 (VDA-2, VHP-2, whatever) and I'm talking about the nice smooth finish on the front plate.

I know almost nothing about capacitors, but have it on fairly good authority that the frequency correction network on my old ESL63's uses an old Electrolytic-type capacitor which is not particularly good for this function, and should be replaced with a Polypropylene version at the same capacitance (220uF). Excepting the vast difference in size between these two types, what brands am I looking for? This cap is in the signal path, so quality is of the utmost importance. Voltage rating shouldn't be lower than 250V. It doesn't necessarily have to be a single 220uF cap - two 100uF caps will do the trick, and might be easier to place in the housing. Thanks for your help …

I recently got a Nugget B22 that had been around so I gave it a good tightening and put it to work. Sounds great no issues there. However I have noticed that like the consumer PC speakers I have at work, it picks up Blackberry traffic and passes it through to the headphone. Has never happened to my KGSS in the four years I've had it. So the question. What causes that and is there any way to fix it?

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 t…

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…

Ever made something real quick, going against your feeling that it might be a bad idea? Here is one I did today. It isn't as bad as it could be - it was plugged into a fused variac - but still...

Hi All... Anyone up for a group buy of IXCP10M90S ? This place below seems to have 146 of them and is in Florida. I know I need them for a bunch of projects and could wait but I'm thinking this might be good for everyone. Has anyone ordered from this place before? https://store.nacsemi.com/Products/Detail?part=IXCP10M90S&stock=XSJMZ0000019254&Mfr=IXYS&auth=n&utm_campaign=listing&utm_source=findchips&utm_medium=aggregator&utm_content=textlink&instock=y I'll run it like my others in the past. I'd say 7-10 people is all we need. I'm in for 30

I'm taking a Microelectronics lab course and we need to pick a particular not overly complicated circuit we think is interesting that is in the literature to build and test. If necessary, we are allowed to make use of the VLSI fabrication laboratory but have to design the layout ourselves. Any cool ideas people have for this project? Edit: Forgot to say that unless we provide the transistors/opamps/etc ourselves, we are using bog standard parts. 2N390x BJTs and ancient 4007 MOSFETs. Opamps are some newer version of the 1458.

"There is no innovation in stereo amp design in a sense that there isn't any room for it, its based on an hi quality op amp chip that takes and input signal and outputs an amplified signal, the basic formula is still the same in every amp the difference is the ratio of resistors and caps and inductors used (value ratio which influences RC and LC constants in the cir), quality of components and the op amp chip" That is a quote from a local friend. We were discussing the Eico HF-81. He basically doesn't understand how an amp with bad measurements could sound good. Basically, what is truly important in the sound of an amp? I'm not into this side of the hobby but I'm s…

I was looking around for something to bling my tubes around the base on the casework and found a nice and cheap way to do it for those little amps like the Starving student and CTH, EHHA and others with wee tubes. Looking around in Lowes hardware stores I found these solid brass Brainerd door viewers: If you unscrew the ends you end up with a pair of brass surrounds. One end fits the CTH and Ehha size tubes and the other fits the Starving student tubes so you'll need to buy two viewers to get a matching pair @ $7 or so each. When added to the case, you get this nice bling surround. They are pretty deep as you can see so you may need to trim them down depe…

Looks like Heath kit will be coming back to business. Source Has anybody played around with heathkit's stuff back in the day?

Just fyi: RadioShack Recalls Power Supplies Due to Electrocution and Fire Hazards

I have finished two stage CSG-ACLF-001 AC power filter for audio. I can send one for free to person which has audio experience and can test and write review. This filter decigned for DAC or Headphone AMP or other audio product with total power 150W. Voltage Rating 110-230V AC Dimensions W/L/H 30/60/27mm Earth leakage curent 0.8A Temperature Rating -25C +85C

Hello! I'm going to acquiere a stax srm-3 wired in 117v (originally 100v) Could you please tell me how can I switch it to 230v (France) ? Thanks you un advance!

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?

Does anyone have these issues in PDF format by any chance (I've read a few great articles but they were only pieces)? Thanks

So I have done a couple of soldering projects and both of them have not turned out so great. Just wondering if there is a good online guide or some place I can look to get some decent tips. I know a lot of it just has to do with practice, but I feel as though I am missing out on a lot of the subtle little things that will make soldering in general a lot easier on me. Any help is greatly appreciated.