Passinwind

[quote name='6v6' timestamp='1415269830' post='2598529'] [size=4]Ok, fair enough.[/size] [size=4]For me that devalues this thread quite a bit, because without specifics like schematics, it becomes a build commentary of an effectively private collaboration between you and [/size][size=4] Chienmortbb, rather than an actual build diary.[/size] [size=4]That said, I'm sure the other details you mention will be interesting. [/size] [/quote] This is Cheinmortsbb's thread and if he cares to post a schematic for whatever form his own builds eventually take (or even when he just gets to actually making smoke) we will jump off that bridge when we get to it. My boards and design are just a starting point, not a destination. I was deeply involved in the fEARful cabinet R&D and early build threads, and frankly, that just became so tedious after a while. I build stuff for myself as a hobby to satisfy my own quirky needs, try to help a few friends along the way, and have zero interest in being like BFM or Greenboy or Rod Elliot. I'm new to the Basschat culture and have not seen the cab build thread yet, so I'll take a look at it presently. I sort of envisioned any role I might have in this thread as teaching how to catch a fish, not giving everyone a fish -- things like modeling your own circuits in LTspice and laying out circuit boards in KiCad, for instance. I'm not looking to sell anything BTW, but if Chienmort gets something worked up that others really want to build, I could help make that happen via open share circuit boards available straight from my board fabricator. You guys do realize how crazy-expensive this kind of thing is to build though, right?

Audiokinesis Thunderchild 112 Acoustic-Friendly, homemade 500 watt amp.

[quote name='Oopsdabassist' timestamp='1415217438' post='2598076'] You came HERE? Are you mad? You know what its like here right? [/quote] At least all the beer doesn't taste like grapefruit over here.

[quote name='Chienmortbb' timestamp='1415144089' post='2597289'] [b]Passive treble control, boost/cut.[/b] [i]I believe that the The passive treble control is less noisy than an active one and more musical but perhaps Charlie could comment.[/i][/quote] This is something I first worked out in one of my tube preamp builds a few years ago, and it's the closest thing to 'secret sauce' in my designs. It comes from some very old tube gear design manuals, and the fact that it's passive is only half the story, because its placement in a different stage than the bass and mid controls keeps it from interacting with those controls in potentially undesirable ways, intermodulation distortion and slew limiting for instance. Moving it back in the signal chain a few stages also keeps the earlier stages from further amplifying treble boost noise and potentially reduces distortion generated in those stages. As always, the devil's in the details though. I spent many hours in LTspice trying to find a workable solution, and was kind of shocked when it turned out to sound pretty good. My intention is that you can turn it all the way up if desired, and it still sounds fine, with very minimal hiss artifacts. When cranked it actually redacts to more or less a classic CD horn EQ in the 4K-12K zone, which works well with my DIY cabs that use pretty much pro audio caliber compression drivers. Here are the frequency response models from treble control full-down to full-up: By standard marketing speak you might see this spec'ed as a +10dB shelving filter at 25K on the boost side, but as the graph shows, marketing speak often leaves a lot to be desired. [quote][b]Variable high pass filter, 2nd order fixed + 2nd order variable[/b] - [i]Think of a Thumpinator or FDeck's HPF. Has the dual purpose of controlling excessive cone movement below a cabinet's tuned frequency and also taking the "boom" out of those nasty rooms.[/i][/quote] Yes, both those purposes are part of the classic design brief. In my design I have also attempted to make the HPF and bass control highly interactive, but hopefully in an intuitive fashion. Here are some compound curves showing bass control boosted 1/8 turn clockwise and left there, then high pass control swept from full up (least cut) to full counterclockwise (most cut): As you can see, peak bass boost can move between 42Hz and 240Hz, and many other curves are readily obtained as the bass control applies various boosts and cuts. Again, I was a bit surprised that I just did the model on my computer, built the circuit, and it measured and sounded fine right off the bat. I made a bit of a mess with the first circuit board design, but I am still pretty new at that aspect and fortunately I have pretty decent board rework skills learned over the years through a series of day jobs fixing and modding audio gear and other electronic widgets. Hopefully the new boards are glitch free, they seem to be from the little bit of testing I've done on my bench. Having someone else build up some of my designs should be very useful in refining my craft, which is the main point of doing DIY builds in my case.

[quote name='6v6' timestamp='1415139554' post='2597224'] There have been references to your design but no links, for those of us who've not followed the TB threads closely (I had a quick look a the link from post #6 but didn't spot the schematic), can you share links to the design's you're referring to and have been collaborating on? [/quote] I'm not planning on posting an actual schematic at this time, but I will be happy to show build pics, component details, block diagrams, performance measurements, and modeled behavior of the various bits. Talkbass messed up their links quite badly with the software "upgrade" a few months ago, unfortunately. This thread shows the evolution from a modified ESP (Rod Elliot) board to my own basic preamp design: [url="http://www.talkbass.com/threads/oh-no-another-diy-rack-preamp-thread.600314/"]http://www.talkbass....-thread.600314/[/url] . The beginning of the thread linked above details the added daughtercard incorporating a variable high pass filter and a one band fully parametric EQ. So there are 6 basic modules available thus far:[list=1] [*]Input gain stage and active bass and midrange control, optimized for active basses [*]Parametric equalizer [*]Passive treble control, boost/cut [*]Effects send/receive/aux input [*]Variable high pass filter, 2nd order fixed + 2nd order variable [*]Final gain stage/line driver [/list] Some of the modules can be placed in varying spots in the signal chain, but my first build is in the order listed. I made the PEQ and HPF modules bypassable by switches on the front panel. I think Chienmort is contemplating using a switchable mid frequency as well. My website at www.passinwind.com has a basic overview of many of my more recent DIY builds as well, along with a few sound clips. There are also a few sound clips here: [url="https://soundcloud.com/passinwind/sets/diy-cab-preamp-demo-clips"]https://soundcloud.c...eamp-demo-clips[/url]

[quote name='VTypeV4' timestamp='1414892464' post='2594495'] I'm reasonably happy understanding valve gear and it's details but Switch-mode supplies, multi-vibrator circuits and Class D amplifier operation is somewhere just beyond me at this time. [/quote] There's a pretty good technical thread on Talkbass by Bobby Baldwin, an amp engineer at Peavey who actually designs Class D amps from a white sheet: [url="http://www.talkbass.com/threads/class-d-illustrated-lots-of-pics.1083366/"]http://www.talkbass....f-pics.1083366/[/url] I haven't taken the dive into that deep pool as far as DIY building just yet, but in time I hope to. I am definitely looking forward to seeing how Chienmortbb's builds evolve -- there are just so many compromises and tradeoffs involved with this sort of project, and at some point one just has to pay their money, make smoke, and see what happens. After I built my amp I revised both preamp circuit boards, and also designed a bespoke power supply, so it's not as if Chienmort will just be building up a known-good design from a blueprint, although we certainly both hope it will play out something like that. A good part of the end result will depend on his own choices and tweaks. I have tried to make my design pretty accommodating to modifications...we'll see how that goes.

Well, there goes the neighborhood. Plenty of familiar faces here, no need to leave on my account.