Passinwind

[quote name='Badass' timestamp='1433433948' post='2791068'] Has anyone made a passive / active D.I.Y. D.I. box? Or a valve D.I. maybe? [/quote] All of the above. Passive: just used one of the schematics on the Jensen Transformers website. Voila, Radial JDI clone. Active: threw a Creation Labs Redeemer buffer in a Bud box with a Jensen line transformer, compared well head to head with a J48, Countryman, etc. Tube: this started out as a DI project but somehow eventually morphed into a full blown bass preamp: [url="http://www.talkbass.com/threads/a-diy-tube-preamp-line-driver-by-passinwind.345415/#post-4388452"]http://www.talkbass.com/threads/a-diy-tube-preamp-line-driver-by-passinwind.345415/#post-4388452[/url] You could easily adapt one of John Broskie's smaller format kits into a really nice tube DI.

[quote name='Painy' timestamp='1438639398' post='2836099'] Just pondering recently if such a thing was available anywhere and wondered if anyone on here had ever seen or heard of one they could point me towards? [/quote] Craig Anderton published his design for one many many years ago, in [i]Electronic Projects For Musicians, [/i]which is still in print. I intend to take a stab at my own take on one pretty soon as well.

[quote name='Wolverinebass' timestamp='1438286729' post='2833336'] These days the fashion is to have a more DI authentic type response from one's cabs. So that the DI you take from your amp (I'm assuming a post EQ DI here) will be the same as comes out one's cab. My question is, does anyone actually make a cab or range of cabs which do this? If so, whom? Barefaced? Bergantino? Mesa Boogie? TKS? (just to name a few of the higher end brands) I'm discounting Markbass as their cabs have all sorts of weird notches and peaks in them and obviously Ampeg and Ashdwon as theirs are massively coloured. Okay if you like that sort of thing, but rather unfortunate if you don't. Do any manufacturers actually have anything that can deliver this boast or is it all just marketing pants and you should just use your own ears to determine if the "colour" on offer is the one you want? I'm curious to gauge people's opinions on this and if this claim whether justified or not plays any part in what cabs people buy for themselves. This is of course on the assumption that you could afford anything and didn't have to buy a 10 year old Ashdown Mag 4x10 for £50 off Ebay. [/quote] I like cabs and amps with minimal baked in voicing, but I also believe that everyone should use their ears and do what makes themselves and the paying customers happy. As a long time sound provider I would tell you that your onstage rig is never going to accurately portray what happens at FOH in a dance club over the course of a night around here, but in a jazz setting there is an excellent chance it will. So as usual, it just depends.

[quote name='alexclaber' timestamp='1437575024' post='2827200'] Class D amps are not digital: [url="http://www.hypex.nl/docs/papers/AES120_353BP.pdf"]http://www.hypex.nl/...ES120_353BP.pdf[/url] [/quote] They also do not have to use an SMPS and plenty do not. There is also a pretty nice technical discussion [url="http://www.talkbass.com/threads/class-d-illustrated-lots-of-pics.1083366/"]here[/url] that may clear a few things up, or not. ;^}

[quote name='JapanAxe' timestamp='1437338932' post='2825202'] The Behringer Ultra-G will take a speaker-level signal (jacks only) and send a balanced output, with or without 4x12 sim. There are two 20dB pad switches to bring the line level down to undistorted levels. [b]WARNING[/b]: Beware of doing this on a class D amp, as I think I am right in saying that this would cause a short to earth in the power section. Cue magic smoke. Likewise amps operating in bridged mode. I welcome better-informed comment on this! [/quote] Andy Field from Genz has mentioned those exact issues. Old Fenders just used a simple resistive tap to ground right off the transformer secondary lead for their line out jack, which works just fine for DI duty IME. Many non-Fender tube amps do use a grounded output config as well. And any amp will have some back EMF downstream of the power section, and the DI will potentially sound at least a different because of that -- not necessarily in a good way though. Harvesting that energy is part of the black art of Class D MI amp design, actually.

[quote name='MoJo' timestamp='1437245646' post='2824674'] It's one of those statements I've heard more than once, 'class D amps can be loud but they don't carry. You can't hear them at the back of the room'. Is this another urban myth. Volts are volts, right? [/quote] http://basschat.co.uk/topic/266141-wee-article-to-help-demystify-amps/

[quote name='AttitudeCastle' timestamp='1437238271' post='2824628'] Where do those who have them place them in the chain? I was thinking perhaps one at the very end of the chain to clear up clutter going into the speakers, but also one before my compressor, so the compress can squash less as there is less peaking down low. [/quote] It's one of those "just depends" deals. In my own designs I put it just after the EFX return, so I can use it with other preamps patched into the return and it also doesn't affect the EFX send. I know other guys who prefer one in front of the whole amp, somewhere in their floor pedal chain, or just in front of their power amp. Glad my little graphs were instructive. I do a lot of that sort of modeling and it's very easy for me to put something like that together. The Thumpinator's curve is likely to be a little different, the one I posted is just from [url="http://www.talkbass.com/threads/a-diy-500-watt-bass-head.1061473/#post-15624273"]one of a few different ones I've designed and built[/url], and at one particular setting that I actually use a lot..

[quote name='Chienmortbb' timestamp='1437117598' post='2823644'] Sure to some the idea of the sound or response changing if the cabinet is rotated is ridiculous but allegedly many silly things change the sound of a cabinet. To me it appears that there will be very little change but if the driver is closer to the floor then there will be a change, albeit quite small. The question is clearly prompted by the idea that tall is better than wide for bass drivers, when used in multiples. On a final note, having read many forums/ threads on speakers, there are more daft answers than daft questions. [/quote] It's really worth getting Vance Dickason's book and reading up on baffle step, he provides polar graphs that are pretty helpful. This bit of free software may provide some food for thought as well: [url="http://www.tolvan.com/edge/help.htm"]http://www.tolvan.com/edge/help.htm[/url] . You need more complicated software to get the polar models, which are what you really want though. The reality is a whole lot more complicated than what The Edge shows you. Boxsim is free and goes a good bit deeper, and if you're really masochistic Akabak goes further still. Note that all of this is independent of multiple drivers and their mutual coupling issues. And in the case of the cab in question I would expect the difference to be pretty minimal.

[quote name='stevie' timestamp='1436972126' post='2822470'] The interesting thing about this Beyma driver is that it offers the best of both worlds. It goes as low as the Kappalite LF (in this cabinet) with comparable excursion capability, but its response is well behaved up into the midrange and HF. Despite the fact that it has a much longer coil than the Kappalite HO, its response actually extends higher. I've scoured the spec sheets for a comparable chassis from other manufacturers and I can't find one, even at a higher price. The downside is that its thermal power handling is lower and it's 1.5kg heavier, but that's not much of a price to pay for the huge difference in price - at least on this side of the pond. [/quote] One of the biggest driver suppliers for DIY'ers in the US is already a Beyma dealer and they are typically quite responsive to requests for stocking things they don't currently carry. Assuming this design gains traction, I'm pretty sure they would take a good look at doing so in this case. How that pans out for pricing remains to be seen though, I might ask them just for the heck of it. The SM112 is listed at $170 on that site at the moment. For myself, I can probably get Eminence drivers at wholesale, but I'm already pretty well set with my current 112 cab in any case. I'm always happy to see more well thought out DIY designs floating around though.

[quote name='Phil Starr' timestamp='1436947628' post='2822190'] They are quoted at £202 which is about $300US over here the Beyma is around £80 at the moment, a big saving. If we could have the Eminence at around £100 I think we'd have gone for that, the mid rise it shows would have given a more 'commercial cab' sound but with better bass handling than a lot of commercial cabs. [/quote] I imagine I'd like the 3012HO a lot in the right implementation. I've played through a couple of different cabs with OEM Eminence drivers that split the difference between the HO and LF models and they are both really nice. My Thunderchild cab is one of those, the Baer ML112 the other. Roger Baer's OEM driver is the closer one to the HO.

[quote name='Phil Starr' timestamp='1436914138' post='2822101'] This design might work quite well with the Eminence 3012HO which is prohibitively expensive over here but which might be cheaper in the states. We did have plans to try one at one point. [/quote] Listed price online is ~$190 USD at the moment, so maybe $150 or so from the right dealer.

[quote name='AttitudeCastle' timestamp='1433456766' post='2791331'] I'm really curious about these, as I really notice on EQ's with 20-30Hz controls when they are wound down, but they aren't designed to do exactly what the thumpinator does. [/quote] Not in the least. Here's a comparison of cutting about 8db at 20 hz with a fairly typical amp's tone control and using a high order HPF set at 32Hz:

[quote name='stevie' timestamp='1436892396' post='2821809'] It's my own design - which means it's not necessarily helpful for comparison purposes. It's also a work in progress. The main component is a BMS 15N620 in 4 ohms (I believe Passinwind has a cab with something similar) It's all good, clean fun, but I hate doing the woodwork...... Phil has said he might build me a cab for this design in poplar ply - which could be interesting. [/quote] My cabs use the BMS15N630, they are 8 ohm drivers. I have used a lot of BMS compression drivers in various builds too, they are especially nice. When I started building cabs with dedicated mid drivers Audax came up a lot and I would still like to try them. I settled on readily available B&C 6MD38s as used in some EAW PA cabs, and still have a pair of those in my PA tops. I also don't really enjoy woodworking all that much. I have a luthier friend who has lots of cab building experience, and a well equipped shop quite near me that I could use for free, or maybe a six pack. I am stubborn and have always just built outdoors with rudimentary hand tools -- not so smart. The Beyma S212 is not readily available in the US through any of my usual channels, FWIW. If I were building this design I wouldn't let that stop me though, there's always a way.

[quote name='Chienmortbb' timestamp='1436883217' post='2821675'] You spotted the deliberate mistake.Actually I cannot find that value at the moment so I am going through my stash to find it. [/quote] That particular value was used because I have a stash of ultra low noise resistors found on eBay that happened to be 18.7K ohms. I bought 100, at something less than 5 cents apiece. There are many great deals out there on oddball values that get surplussed when a production run ends. I would leave that one in there and stick with the gain staging arrangement as-is in that spot. A pot would vary output impedance along with gain, which may or may not actually matter to you, probably more so if using an output transformer. On my newer build I didn't bother with an HPF bypass. I used that position for an active/passive switch instead, making the front end impedance switchable from 18.7K to 330K. Doing it that way keeps the 330K resistor out of the circuit when not in use, cutting thermal noise a little. Little things add up though, and it could be that the switch wiring will be noisier than that resistor. This is stuff that's pretty specific to your build though. The effects I use are mostly time domain ones, which a parallel config usually works a little better for IME. I also like to use the EFX return as a mixer, adding another bass preamp or even a vocal feed for quick and easy monitoring at rehearsals. Could be handy for piping in canned music as well. The way I have set the board up allows both series and parallel operation if you want maximum flexibility. Series loop normalling jacks are a notorious failure point though, FWIW.

[quote name='Chienmortbb' timestamp='1436874748' post='2821527'] Ironically the omissions make for a more satisfying build. I am studying the circuit diagram/schematic more closely than I would if documentation were 100% and learning more as I go. The Pre amp board is now complete apart from the wiring. Some of the components are now mounted off board as the preamp was designed before the HPF/PEQ circuit and taking components off board allows us to configure the circuits to the best arrangement. Below is the picture of the completed board. It still needs to be wired but I will leave that until the front panel is complete. As you can imagine I am taking more time and care over the front panel as it will be on show more than the back panel. [/quote] Nice job. Are you using a pot for setting final stage gain where R24 would go? And I also agonize a lot more about front panels than the back ones.

I can tell you're making real progress now by all the emails asking for clarification of my shockingly shoddy documentation. There are so many little details that I've just taken for granted, things I've changed eleven times then changed back, and so on. As you say, I have been using this design pretty happily for a couple of years now though, so hang in there. My latest tangent is an onboard preamp based on a simplified version of that board in your last post. Just bass, mid, and treble controls, with mid frequency switchable to three frequency centers. It was a challenge to make it small enough to fit in my target bass, but it is done and I should be auditioning it in the next day or two.

[quote name='mrtcat' timestamp='1436209773' post='2816054'] Agree in terms of the tech but have they seen such a significant size reduction in cabs? Actually I guess all the skinny column speakers and 12inch subs would suggest that they are leading with that too. [/quote] That was my thinking, but things like powered 12s and 10s on sticks actually work pretty well for a lot of people these days too. Or to look at it another way, big old stacks for front of house may still be fairly big and heavy, but that are a lot more capable than they used to be, and the amp racks are a lot lighter. In any case, I can often do fine with a 33 lb. 1 X 12 on my gigs that used to require a 2 X15 rig, and I'm not complaining a bit!

[i][b]Bass world surely leading the way?[/b][/i] IMO, hardly. Pro sound reinforcement pretty much drives the bus and we get crumbs eventually.

[quote name='Dan Dare' timestamp='1435921751' post='2813615'] As stated above, BBE + Peavey into the 2x10 [b]makes the right noise, but not at any volume[/b]. [/quote] That's the exact same experience that many of us have had with most Fender all tube amps used for bass. An inherently scooped tone stack wants lots of power, and even then, the natural loudness curve that our ears work with are just not the greatest fit for that when we turn things up. So exactly which Fender sound are you looking for? My benchmark would maybe be Phil Lesh ca. 1970, how about yours? The preamp Chienmort mentioned was based on [url="http://sound.westhost.com/project27.htm"]ESP Project 27[/url], not all that different than the BBE Bmax or Bmax-T. In my experience the Alembic F2B or F1X models do cop the sound just a little better, especially the F2B. I owned an F2B for a little while but didn't really find it to offer much over my solid state one once I turned up though. I modded one channel of my F2B to actually be able to boost mids and the guy who bought it greatly preferred that channel by itself, even though my intent was to mix the two channels -- go figure. In any case, I'd start with an 8 X 10, not a 2-by. For me a really robust 2-15 would do better, and there are at least a few relatively lightweight modern production ones that have the right vibe. I'd leave that alone until you sort everything else. IMHO, lots of power is going to be key, and I'd set 500 watts as the lowest workable figure if given modern solid state power amp sections. Best of luck getting what you want and need.

[quote name='Phil Starr' timestamp='1435832015' post='2812787'] Oh, someone asked the weight of the cab. It is 14.2 kg. [/quote] Nice. My Thunderchild 112AF is 15 kg (w/ two tweeters no less), makes for an easy one hand grab.

And the beginnings for a few different onboard preamps: 3-band board, based on the half-rack preamp in the last few pictures above: 3-band, kind of a hybrid of Music Man and Bartolini NTMB circuits, done both through-hole then with many surface mount part subs: Should be building up the first one in about a week's time or so. Edit: and here it is:

[quote name='Chienmortbb' timestamp='1435690807' post='2811548'] Two more questions then. Is there such a think as void free ply. I mean can you order bios free or do you just have to purchase and hope. Secondly what is a void? I can only imagine knit holes or possibly where two sheets of veneer have not been lined up properly before the adhesive sets. [/quote] I should really know a lot more about this subject than I do, given that plywood production was the #1 industry in my little hometown until very recently. The company that makes the [url="http://www.columbiaforestproducts.com/product/europly-plus/#"]sheets I used in my last few builds[/url] have a pretty comprehensive online guide to grading: http://mydigitalpublication.com/publication?m=29753&l=1 The Europly that I used was a little different than the newer spec, with alternating layers of alder and birch. Pretty heavy, but a total joy to machine and quite attractive for natural finishing. Expensive as all get out too.

[quote name='alexclaber' timestamp='1435674910' post='2811291'] I bet it's that same thing I referred to earlier, about many lightweight amps not being able to deliver full power for long enough. So you get the attack of the note at full loudness but you don't get the WEIGHT of the note because the amp has run out of power by the time that comes through. [/quote] Much as with speaker cabs, amp designers walk a tightrope of compromises to meet particular market slots. The commonly used ICE 250ASX2 can make full rated power of 500 watts bridged (8 ohms) for about 50 seconds at room temperature, yet it can only make 180 watts continuously without eventually shutting down. That's with a sine wave though, and that's not our game here. Duty cycle of the bass signal and cooling management are key factors in real world performance, and those modules were just never made with bass instrument amplification in mind. Yet many people love these amps, partly because not all of us need or crave a lot of low end energy in the lowest audible octave or two. The newer ICE modules don't need a fan at all and are predicated on a much more reasonable 3:1 duty cycle rather than the 8:1 figure that is pretty standard in home hi-fi and general purpose sound reinforcement apps (ie non-subwoofer duty). Many of us who do crave more beef down low have resorted to using multiple kilowatt pro sound amps regardless of class of operation or topology of power supply, and that can still be a mixed bag IME. And then again, as with speakers, transient response matters a great deal, so much so that the front side of the note may be more important to many than the sustain/backside aspect. IOW, there's more than one way to run an amp out of gas. Looking forward to seeing what you come up with Alex.

[quote name='wateroftyne' timestamp='1435472945' post='2809009'] . The TC was - IMO - dreadful (and I'm sure that uses a B&O derivative?).[/quote] Derivative, yes, but AFAIK not an actual ICE module. Unfortunately a lot of the online tech info on those amps disappeared after the power management/ratings debacle. Not my cuppa at all in any case.

[quote name='wateroftyne' timestamp='1435470758' post='2808998'] I was under the impression most of the amps we're discussing here use a similar variant of the B&O module. [/quote] Not really, at least in the case of Markbass, Acoustic Image, Ampeg, Carvin, Peavey, T.C., Ibanez, Vivid, Hevos, Jule Amps (non-Demeter versions), Bergantino, and the earlier Euphonic Audio, Aguilar, and Tec Amp Class D amps. But in any case, perhaps you'll get on better with the newer ICE modules that were designed more specifically for bass instrument applications -- I know I do. I also like the older ICE ASP series modules as used in the Bergantino IP powered cabs a lot, but AFAIK nobody was using those in commercial bass heads until very recently.