Do It Yourself

Not sure which forum is the most appropriate place to post this topic. since it's technical in nature I chose this DIY forum. My question is - which Stax amps can one safely use the KT77 in place of the EL34 output tubes and why. Judging by the KT77 spec as stated on the datasheet, it should be compatible to the EL34 in terms of plate voltage and dissipation, etc.. But it has been stated by many that the KT77 should not be used in the BHSE. Can someone explain the technical reasons behind it? Also, what about using the KT77 in the Grounded Grid, Megatron and the DIY T2 and why. For me, it's both a learning exercise as well as a practical question - I've use…

I was adding a switch to my brother's NewClassD amp, but am having a curious situation. The switch was to go between SE->bal (4PDT), wired up basically like what Kerry did with the relays on the mini ss DYnalo: Everything ohms out correctly, but when I went to test it, the R channel works perfectly (in either position), but no sound from the L channel. I took it all apart tonight (not the switch and input wiring), but disconnected from the amp boards, etc. Everything once again ohms out perfectly, no shorts. L- and R- shorted to gnd when switch is in SE position, straight thru then not. The XLRs are the metal Neutriks like the NC3MD-LX-HE, etc. The only …

Do any DIY experts have any any intel on modding Stax cables to be removable at the earspeaker ala the Stax SR-L700MK2 ? I'm interested because I have a couple of worn out Stax, the cable is fatigued at the strain relief up top and is causing drop outs and static. I've seen youtube vids regarding this fix, but am leery that the connectors used may not be able to safely handle the voltages involved. The connectors are circular four pin mini bayonet style, gold plated pins with what appears to be a black phenolic plastic insulator around them. There is no mention of part numbers used, other than that MrSpeakers sells these connectors. On his website, he …

One of the tweakier things I've done. My twin brother is back in the states for a month and brought a couple of pairs of KZ ZS-6s with him that he has had for awhile. He had previously talked me into buying a pair of KZ ZS-10s, but I found them unlistenable due to their excessive high end. A few months ago, I had run across a post on diyhifi from Thorsten Loech (aka, Kuei Yang Wang) regarding some mods he had done to these. These are apparently a clone (looks-wise) of Campfire Audio Andromedas, which he apparently liked. Patrick (EUVL) on diyaudio also did this and seemed to like them, so WTF. Like I need something else to do right now. I sent a link to this to my brother…

Apologies if this thread already exists. I wonder if there are any experienced builders here, who would like to build an amp for me - for a good fee of course? I live in Finland, so EU location would be prefered. I am thinking about the current feedback amp, because I need to keep the physical size of the amp smallish.

Hi all, Im planning to build a blue hawaiii using the version 6s bipolar amp boards (kgbhver6sbipolar.zip) and the kgsshv dual 2 new power supply, (kgsshvpssicfetdual2new.zip) Gerber files are in https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k Has anyone tried this combination? will the psu provide sufficent current (the voltages are fine +-400V -+15V and 580V) Does anyone know what ratings I need for the transformer Im guessing for the secondaries 2x 6.3 5A (el34s draw about 1.5A each plus I want plenty of headroom) 2x 360V 230mA 18-0-18V 200mA Does the kgsshvpssicfetdual2new offer delayed start for…

Anyone has experience with the Ebay kits for the KGSSHV Carbon: https://www.ebay.com/itm/Power-supply-PCB-for-KG-Kevin-Gilmore-KGSSHV-CARBON-Electrostatic-amp-L9-50/123415369465 and https://www.ebay.com/itm/Kevin-Gilmore-KGSSHV-CARBON-Electrostatic-Headphone-amplifier-bare-PCB-L8-39/123327894674 The names contain "L9-50" and "L8-39": are these version numbers ? I'm interested in building a KGSSHV Carbon and any help is appreciated.

Anyone know anything about these? How would these compare to Amb's regs, or even the micro GRLV? Someone asked me about them. I'm normally very leery of the shit that Partsconnexion sells (Bybee? Burson? etc.). https://www.partsconnexion.com/BELLSPX17-85570.html https://www.partsconnexion.com/BELLSPX79-85599.html

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

I want to match some PRP resistors to 0.10% so I read tangent's blog on this and I need a meter with 10,000 counts or better. Is this worth doing or am I wasting my time? I was wondering what everyone else's experiences were?

Any of you ever across this stuff? Discrete opamps and 78xx/79xx Vregs? https://sparkoslabs.com/ Wonder if the regs are any good and how they compare to Amb's o78/o79?

....so I bought one of these. They popped up on Massdrop while I was talking to Kevin who immediately called BS on this. My curiosity peaked, I had to get one. Here is the product page: https://www.bursonaudio.com/products/supreme-sound-opamp-v5i/ BS meter is tingling so I waited for it to arrive: Nice enough box and here are the internals: I forgot to take a picture of the top but it looks exactly as it did on the page. Here is the bottom though: The potting compound is pretty soft so here is what I found: So... the only thing in there is an opamp with the top markings sanded off and one small cap. There is noth…

I am moving Kerry's mini GRHV\GRLV GB discussion to its dedicated thread here. I also included JoaMat's mini T2 here to see if we have enough interest for a GB. The table will be updated periodically as more people participate. Apologize if I missed someone or something - just let me know so I can correct the data. I put down one set for those that have not decided on the number of sets they want. The plan is to have assembled GRHVxxx boards, rest of boards will be PCB only. See discussions on the PS in this thread. mini T2 build discussion in this thread. Construction notes: R3 and R2 determine the regulated voltage for GRLV. The …

planning to build an electrostataic amp for my SRM L700. I have built several amps for my Moving coil earphones (HD650, K601, K702...), but never built an electrostataic one, I read some topics about it, also some diagrams of amps , there are still some questions need your help. 1. Never saw the full differential structure (for example, opa1632, lme49724) used in the electrostataic amp, why? 2. The electrostataic earspeakers have much larger impedance than moving coil ones, the only capacitive impedance is isolated by the output resistor (usually 5.1k), so...the electrostataic amp works like without loads? 3. Why the output resistor is usually 5.1k ? …

I am starting this thread for all that are or will be building JoaMat's mini T2 to share information, ideas, thoughts and experiences. The attached schematic is an updated one .The resistors in the BOM are thick film ones and can be replaced with thin film ones for likely better outcome. The power supply requirements for this amp are +400VDC, -460VDC (EL34 output stage), +220VDC (6922/6DJ8 front end), +15VDC, -15VDC (servo, cathode current source) and 6.3V filament supplies for the 6922/6DJ8 and EL34 tubes that can either be AC or DC. I also plan to use the +15VDC for the CPC1117N high tension delay. EDIT (Feb. 2020): updated schematic and BOM (Thanks Joa…

I know some of the newer and cheaper Chinese digital scopes are all the rage (Keysight, etc.) I am toying with buying a refurbed Tek 2465A, completely working, for a decent price. I know these have a proprietary IC in them, that if it fails, turns these into a doorstop (though I seem to recall this IC being available now...). Good idea or bad? For some reason, I've always wanted one of these... Flail away.

I'm just finished school about to be working as an electrician and my teacher swears by butane soldering irons. She's had the same one for 20 years. It looks like they can be used for melting heatshrink too. Does anyone have any experience with these?

Hello, I would like to inquire about "caps in the bias supply" for Stax headphones. Spritzer and others said several times that "caps should not be used after the ballast resistor" (for example here: ) In this quoted case it refers to a cap in parallel after the ballast resistor. In other places the same is said about the cap in series, after the ballast ( What problems does the cap cause exactly, in that position? May I ask an opinion about the attached "blinker" circuit (with a series cap...), of which I read a long time ago; I have used one like this for a long time "without adverse…

I have question about how to hold a rubber sealing ring in place when closing two halves of an electronic component. I'm trying to assemble a backup controller for my ebike. I want to match up the good front from one controller with the good back from another. There is a rubber seal to go between them. The problem I'm having is that the seal won't stay in its groove dry. Would it be ok to use something like a bit of Vaseline to hold the ring in place? Maybe something else?

I came home from out of state on Sunday and noticed my preamp display was awry (L-R arrows flashing, mute on, front panel non-responsive). Last night I took a look at it and it seemed to return to normal upon running signal thru it (CD->pre->headphone amp). This is a Classe CP-50, probably mid-90s vintage. From reading the owners manual, the display I was seeing is what is supposed to be there after a power outage, but I thought after 45 seconds or so it was supposed to go back to normal? At any rate, I have it open now and think I will recap it. Most, if not all original caps are Nichicon VX(M), 85C, standard series, 2000 hour life (from what I can tell). This…

If I take say 1 120 Ohm 5 watt wire wound resistor for each channel that's sufficient for a dummy load correct?

I was just wondering how this amp would work as a headphone amp. It doesn't have a headphone jack but the speakers are connected with rca plugs into rca jacks on the back of the amp. It is rated at 1.2 watts at 1000 Hz with 10% distortion. I read that it puts out .75 watts per channel with very low distortion into 8 ohm speakers. My question is how would it work to connect headphones directly to the speaker jacks with an adapter? Would any modifications need to be made? These little amps actually sound really good with small bookshelf speakers and are dirt cheap. Thanks a lot, Gene PS I have asked this same question on several forums this morning. Sorry if …

OK, so I did something stupid and accidentally shorted the secondaries of an Avel Lindberg Y23 transformer for two seconds. The voltage seems fine after I corrected the error. Do you think it survived, and or what's the harm in using it?

Has anyone built this balanced beast and tried it out?Rightmove Kijiji Quizlet

Hey all , so this is my first post here so sorry if its not up to par. Recently i bought a Srm-006t amp 404 signature combo . I loved the sound but it seriously lacked volume . I replaced the tubes with a new set of EH tubes .. but aside from a uptake in tone .. I didn't get any extra volume . I started searching Google for mods to this energizer and came across a post by Kevin about a cascade mod for this amp and mention of an article in Audio Express July 2017 edition by James Lin. In the thread i was reading i saw that a board had been designed (im really not a fan of point to point electronics) and messaged Kevin Gilmore about it , He said he was all out…