Passinwind

[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.

[quote name='Chienmortbb' timestamp='1435392793' post='2808298'] Phil, you have no need to apologise. Life gets in the way sometimes and you are offering your collective expertise free to the community, Having started on an amp build I have had the same problems and it always takes longer than you think to get it right. However it is no cheaper to build your own amp but it is possible to get a self build speaker at close to half the price of a commercial offering. Arguably time better spent than my amp build. [/quote] I've only built amps with unique feature sets not found in commercial offerings, so what it cost was sort of moot. But even with cabs, if you mentally pay yourself a reasonable labor wage DIY building is pretty much always a losing proposition monetarily, in my experience. Since I don't enjoy woodworking particularly, using a proven design such as the one in this thread will eventually be is a pretty nice hedge against huge budget bloat, and the design efforts are much appreciated.

[quote name='wateroftyne' timestamp='1435400215' post='2808398'] I don't think the Crown or D&B stuff uses the same ICEPower module as the lightweight heads being discussed here. Until that changes, I think there's a lot of truth being spoken here. [/quote] Not all bass amp makers doing uber-lightweight small heads use the same ICE modules either though (although many do), and even among the ones who do, IME they don't all sound the same. So my take is that implementation is everything, same as it ever was. I didn't really like very many old school amps back when they were contemporary, don't really like too many new ones either. Yet I sound just like me through just about anything. Doesn't keep me from still trying to improve the sound reinforcement aspect though -- maybe I'll get it right in the next forty years!

[quote name='Bottle' timestamp='1433608550' post='2792510'] Coming together nicely [/quote] Indeed.

A few recent DIY builds: Music Man Stingray 2-band preamp with many component mods and my own layout: DIY 500 watt bass amp: Tube bass preamp: 1/2 rack width bass preamp and matching 700 watt power amp module: These are all hobby builds, nothing to sell here. Maybe someday though.

[quote name='EBS_freak' timestamp='1431727496' post='2774506'] I know there are loads of channel strips and the like about... but this relatively cheap effort from Rolls, seems to be incredibly flexible on the tone shaping front. Anybody ever used one with their bass? [/quote] Not the Rolls unit, but I've used similar analog parametric EQs from Ashly, Symetrix, Rane, DBX, and Orban, for starters. In most cases they've tended to work best with a dedicated preamp in front of them. I also have used my Rane RPM26z, which is digital and IIRC can do up to 150 bands of fully parametric EQ.

[quote name='Wilco' timestamp='1431372012' post='2770675'] Don't think I've explained myself clearly enough! I use the B115d as a monitor in a full band set up. I'm thinking of using it just as an amp for the acoustic bass, but would it not need a passive DI box between the instrument & the B115d? Also, how well would that set up work at modest levels? [/quote] A passive DI box reduces level quite substantially; what you want is a preamp, which you may or may not already have in your bass? Many outboard preamps already have a DI function as well, should you want to also send a feed to the front of house mix. I have no experience with the B115D, but various QSC and Mackie powered speakers have often worked really well for my electric upright, although always better with a little more drive than my onboard preamp can readily provide.

[quote name='Wilco' timestamp='1431370133' post='2770643'] Resurrecting an old thread here, so apologies if there's been anything since. I've just bought an electro-acoustic fretless from Haimsey on here, & already own a B115D as a monitor. I don't need deep bottom end, but clarity. Should I need to raise the volume a little (not in a full on band setting, but with couple of acoustic guitars & vocals), a passive DI box in between the two should be job done shouldn't it? [/quote] Pretty much every active cab I've encountered already has a line level output jack for daisy chaining multiple cabs.

Which model did he clone? AFAIK Francis has still never released the V3 schematic?

[quote name='Chienmortbb' timestamp='1430915283' post='2765856'] Stevie Rod has some good articles on valves and valve amps and links to some good resources. They are all worth a read. I think this is an excellent project. Has given me a few ideas although I am trying to resist feature creep, Now back to my project. [/quote] There are definitely some things in there that could integrate well with the boards I sent you. Personally, I'm glad that Rod didn't post that until after I tried my hand at something like a white sheet design, although I already did lift a few ideas from some of his articles that are not full on "projects" per se. For those of you who haven't seen it, this is how my second version of the preamp design Chienmortbb is using came out, shown in one stacking configuration with the matching 700 watt power amp module: :

[quote name='Bobzilla' timestamp='1429605678' post='2753004'] So I would need a dual sweep for the frequency (guessing because it is the resistors either size of the boost/cut pot that determine the frequency, dual sweep for bass/'treble, dual sweep for mid and volume, so three dual stack potentiometers? Have I got that right? [/quote] You would need dual stacked pots for many of the more common sweepable tone control configurations, which generally split the bands up into separate sections, both to minimize interactivity and to improve headroom. Have a look at Rod Elliot's new bass preamp project for a different approach though: http://sound.westhost.com/project152-1.htm . The tradeoff here is more opamp sections in lieu of a dual pot -- as usual, there's no free lunch.

[quote name='Beer of the Bass' timestamp='1429012302' post='2746956'] I'd be curious to see whether anyone thinks this idea has legs or if it looks like an exercise in futility! [/quote] I'm not positive, but I think those are the same drivers my friend Duke LeJeune used in this experimental 4 X 6 cab last year: I played my EUB through it pretty happily, but to me it seemed better suited for acoustic upright. He has now done a similar one with four of the eight inch Faital 8PR200 drivers, which strike me as much more BG-friendly. I'll be interested to hear how the P.Audio choice works out for you, as I could often use something smaller than my 112 cab at quasi-acoustic jams and the like.

[quote name='Bobzilla' timestamp='1429261613' post='2749712'] I want to build my own pre-amp for a bass-build. I'm good enough with a soldering iron to do it, and its a nice little project for me. I've got a design for a MM 2EQ, but I want 3EQ, and if possible sweepable midrange so I can pick the frequency to cut/boost. So, what designs out there? I want full boost/cut control, not just a boost function. And [b]for the mid I am planning on using a concentric stack pot[/b]. [/quote] You just made doing a swept mid frequency a much taller order, since a dual section pot is often required just for the frequency sweep. Concentric pots like that do exist though.

A 1:1 compressor ratio = no compression. Try the -10dB back panel setting first off if the lowest (most sensitive, -48dB) compressor threshold setting isn't working at all.

[quote name='karlfer' timestamp='1428997267' post='2746717'] the cab doesn't deal with 30 hz, what is actually happening if I cut or boost the bass rotary on my amp ? [/quote] In many common tone controls the peak or shelving frequency varies a lot depending on how much boost or cut you apply. Here is a set of frequency response curves for various settings of one of my preamps. Many manufacturers would call this a 35Hz +/- 12dB bass control (I didn't show all of the cut side), but as you can see that doesn't tell you the whole story by a long shot.

[quote name='Byo' timestamp='1428534438' post='2742297'] That looks amazing! Nice setup too! What is the preamp by the way? Never seen it before but looks supah cool. I guess that I will stick to using my Markbass Little Rocker 500 power section as it makes no sense to spend so much £££ on a power amp. Really interested on your class-D DIY amp, did you use any specific schematics? [/quote] The preamp is a DIY build as well. There's a whole thread on it [url="http://www.talkbass.com/threads/a-diy-1-2-rack-bass-preamp.1135423/#post-16982343"]here[/url], although I kind of hate just posting TB links on this forum and would be more than happy to discuss anything about it here. Here's a front panel closeup showing the control labeling: The power amp box just uses the ICEpower 700ASC module, their current latest-greatest. That still required a fair bit of work to implement, even so. I do intend to do a ground-up Class D build eventually, but that will take some [i]serious[/i] work. The Markbass power sections sound good to me, and the form factor isn't really any worse than any of my alternatives. Funny how we would have to pay more for less in this case, no?

[quote name='Byo' timestamp='1428496135' post='2741777'] Thanks Passinwind, already saw those but they are way out of budget! Lol. [/quote] Yep, there are a couple of running threads on Talkbass and many people want a cheaper solution, but the supply/demand equation seemingly works against that. So naturally, I just built my own. The first used a plate amp similar to the Bag End amp that sifi2112 mentioned -- still more money than just buying any number of bass amps and using only the power amp part, and only a little smaller than a rack mounted pro sound amp. It ended up living in a standard rack anyway, LOL. I am currently finishing up this newer one, which does 700 watts at 4 ohms and weighs about 7 lbs: This will fit side-by-side in a standard rack with a similar sized preamp, or can be stacked on top of smaller cabs, like so: Frankly, I just don't see the market demand being high enough to get the cost down far enough to make business sense, but as DIY'ers can get away without certifications and warranty obligations (at least here), it didn't work out too badly for me.

[quote name='Byo' timestamp='1428362377' post='2740659'] Hi all, Just wondering if, as I have not found much on the net, there are any small and portable class D amps similiar in format to the SWR Amplite. All I seem to find are 1-2 space rack PA amps. I am tinkering with the idea of going for the BAER tube DI thru a class D into a portable cab (Barefaced 2x10's possibly), but knowing me, I will end up going back to my Markbass Little Rocker 500. If anyone knows about a class D similar in format and size to the Amplite, let me know! [/quote] Demeter and Jule Amps both make them, but IIRC both are larger and/or heavier and also considerably more powerful than the Amplite.

Just finishing up yet another DIY amp rig, this time in 1/2 rack width format that can be stacked a couple of different ways or racked side by side in a 2RU effects rack: The lower box has one of the new 700 watt @ 4 ohm ICEpower modules in it, which I'm really enjoying so far. The cabinet is an AudioKinesis Thunderchild 112, acoustic-friendly version.

[quote name='Passinwind' timestamp='1425755465' post='2710451'] I'm just about to order the permanent front panel, which will look a lot like this, in blue anodized aluminium: [/quote] And as it turns out, it actually does look a lot like that, although the blue anodized aluminium stock is a rather different color than the Front Panel Express CAD software might lead one to believe: