Do It Yourself

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…

I've just stumbled across this http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/Analog.html are there other sites of a similar intent that you can recommend. (This is to save me trawling through threads at HF. )

Of course it's not an exact clone due to several changes, but I was wondering what opinions of the project might be. Check it out here/. I'm considering taking that and doing some mods to it or taking the Buffalo and building a DAC around that, or maybe even the PCM1794 or PCM1704. I'm just throwing this out here to see what kind of opinion I get.

Hi guys, I've recently been thinking about having a DIY DAC built, but the only one I know is the Alien USB DAC (or Guzzler's for that matter). What other DIY USB DACs are around? And secondly, how good is the Alien DAC? Cheers, Nanoha

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 didn't find anything in search, which was surprising. Maybe I suck at searching. Anyway, a couple q's for those that own one or more: 1) How do vintage ones hold up? How often do they need recalibration? I'm not talking about serious vintage, with 50 tubes inside, but 1970s to 1980s solid state stuff. 2) Specific brands to look for/avoid? 3) What's the cheapest decent digital oscilloscope that can be hooked up to a PC? This or something close to it is what I'm used to using in the labs (yes I know it's a couple thousand... used): Digital Phosphor Oscilloscopes: TDS3000C Series > Data Sheets : Tektronix Specifically TDS3012B. 4) How useful/not useful has i…

just curious, has anyone tried using other tubes in the Blue Hawaii than the 6CA7/EL34? I ended up with a set of boards, and was looking at some datasheets over the weekend. I started looking at the 6BG6GE, 3D21A/WB/7403, 12E1, EL360, 6146, etc.... I started looking more at the 3D21A, but noted that the one major concern is that the transconductance is about half that of the EL34 which means that the gain will probably be about 6dB lower than the EL34, and depending on headroom in the cathode drive circuit this could result in significantly higher distortion. (Also, I might not get enough voltage swing without making other changes that would raise the source impedance …

ok, I need a quick sanity check. Amplifier input impedance is somewhat arbitrary for the Pass F4, but let's assume 47k, which is the default. Output impedance of my preamp is 100k, with coupling capacitor. My soon-to-be speakers have a f3 of 40 Hz and the driver I'm going to use in my future-to-be speakers has a fs of 48 Hz (it's a 15 cm driver), f3 undecided. I'm considering a 3uF capacitor with a small bypass, maybe 10nF. So, I'm getting 1/(pi*47k||100k*3uF), or fc = 1.66Hz. Opinions?

I'm getting ready to build up one of Colin's tooleaudio I/V stages to put into my Rotel RCD-991. This is a dual PCM-63P player with pcm100 filter. I have currently been listening to it modded with THS4031s for the I/V stage and AD8599s doing the buffer/bal conversion. stock output stage: U302 is the single I/V opamp, U306 is the buffer/conversion opamp (dual) and U304 is an anti-aliasing opamp (socketed now, but not populated. I am trying to decide whether to Retain the AD8599s as buffers/conversion Replace the AD8599s with different opamps Use transformers? If so what? Other? I want to retain the muting relay functiona…

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…

I normally use FMs in most cases, but I see that they have come out with the FR series which are supposedly lower ESR, higher ripple current and longer life? Anyone use these, or are FM good enough? Or other? Use for now would be in PSU filtering for an I/V stage.

I have a strange question. I'm running to an issue paralleling four 2SK170/2SJ74 JFETs where the noise from the degeneration resistors is something I'd like to overcome. I'm wondering if anyone knows of a scheme where at most a single sources resistor is used (i.e. all the sources are tied together before this) and some sort of a a servo arrangement is used. I'm looking for a way to avoid super tightly matched devices as well. I understand the scheme used in the Xono and say the Vendetta phonostages, as well as a number of the Borbely designs, but these aren't exactly what I want. Feedback is acceptable as well.

The speaker protection i have uses 2 relays for stereo channel (1 relay for each channel). But I'm thinking of using it in "mono-mode" and shorting the R+L input and R+L output to make it more "robust". Will that work? (this would mean I would need 2 devices for 2 channels.) Thanks again

Am I the only one to whom this is new? Parts Connexion

For those interested in another solid state circuit; http://www.diyaudio.com/forums/pass-labs/248112-pass-stat-headphone-amplifier-concept.html#post3753546

I'm considering getting a few Pass Pearl phono PCBs made up. Is there any interest here?

I noticed a channel imbalance in my Pearl phono. It appeared out of the blue, was working fine up until a few days ago. Anyone have any suggestions where to begin trouble shooting? Does anyone still have the schematic/build PDF? Pass DIY site only has the Pearl 2. It is the phono, I've isolated every other component including the cartridge. And I'm getting perfect channel balance with another stand alone phono.

Does anyone have or know where I can find a board that would let me mount a single or side by side Amveco PC mount low profile toroidial transformers? I'm just looking for a board that would have AC in and out going to terminal blocks and allow the use of standoffs. Amveco PC mount low profile 50VA toroidial transformers https://talema.com/wp-content/uploads/datasheets/70000K-72400K.pdf If not, I'd gladly pay someone for their time to lay out a board for me. Something like the pic in here

Has any one of you done something like this, accommodating a pair of RCAs and a pair of XLRs, with the appropriate switching for these? I know I'll get told to just use the Neutrik or whatever RCA->XLR adapters for this, but I was thinking about doing up a PCB with a pair of something like the Neutrik NC3MAV/FAV and a pair of RCAs. Has anyone ever used the vertical Vampire RCAs (pcb2f/s)? They don't list any dimensions or PCB layout for these, but just wondering height-wise if these could work well? I had thought I would probably use relay switching instead of a mechanical switch, as the 4PDT are a PITA to wire up, but I suppose just going into a board with c…

I had a problem with the last amp i built with pcb mounted sockets where the tubes werent straight (probably because the sockets werent parallel to the board. anyone have any tips on how i can get the sockets all mounted level so the tubes can stick out straight?

I was thinking of getting some to case up my b22. Mailed perforate.com a hell lot of times and still no reply. anyone know where to get them?

I got a set Sony ECR-500 Electrets from Fungi recently and decided to have a play Insides of ECR. Stripped and cleaned. Getting ready to whittle Whittled! Testing for fit. Parts for assembly. Cable in and felt lining. All assembled. Last shot. Fun little project for the weekend and sounds great.

Saw some talk about this and decided to make a new version. use either the tube unbal/bal to bal board, or the solid state version result is about 125 watts rms into 8 ohms at thd of .005% will definitely drive 4 ohms with suitably large power supplies. transistors are standard pinout, so pick your favorite output transistors. the to220 transistors are mje15034/mje15035 perfect for so many things, including esl boost transformers. pioneera09.pdf

just a general question on tubes. Is there any rule of thumb regarding plate voltages for any given tube? I mean, if a tube is rated for 450V is it best run at the upper end or kept a bit lower? I know little about tubes and what is the best way to run them. Is there a benefit to running higher or lower voltages?

I recently sold my Stello DP200 to laxx, and upon taking delivery, he told me that there is a problem: the headphone jack does not work. He tells me that he feels no physical resistance when plugging the headphones in, and there is no volume. The Stello is supposed to mute the pre-amp outs when headphones are plugged in, but laxx tells me that even with phones plugged in, the pre-amps still work. My first thought is that in the shipping process, the headphone jack became dislodged from the chassis such that it no longer grips the headphone plug completely. Does this sound plausible?