LawrenceH

Unfortunately the weather has stopped me properly testing this, so alas no freq responses/waterfalls, but I've managed to check the box resonance and play some bass/recorded music through it at reasonably decent volume. Shelf port makes the tuning frequency a bit sketchy but it has come out at 58 Hz, so not quite the figure of 55 I'd decided on but perfectly acceptable, reinforcing the upper bass but not giving that dreaded, boomy 'hump'. For testing purposes I used a mixer/DI into QSC PLX2402, a 'proper' PA amp. Incidentally this would make a fabulous amp for a truly high-powered rig that was still light enough for an easy load. Recorded music sounds solid enough, no tweeter means my perception is dominated by the lack of shimmery high end on full range material but it extends high enough for my purposes (much more than a 12" Ashdown blueline, for example) and it is definitely a lot less 'honky' than a Deltalite, sounds quite neutral. The bass is not dominant, there isn't any boom, but it is there and authoritative when the overall volume is turned up - I'd describe it as tight and punchy which subjectively matches with what the model would suggest. Bass guitar on recorded tracks sounded very good to my ears. I tried the cab both unlined and lined, using 1 to 2 inches of Monacor wool/poly wadding throughout except around the port. Testing this on vocal tracks, it surprised me how minor the difference was. I think this may be a combination of the braces and rough ply acting to make the inside a bit less regular, and the wadding not absorbing much below 1k. I suspect that lack of tweeter made a difference as well, I have found before that imperfections are a lot more obvious when you have full-range signal. On bass guitar it sounded very good. I was using a battered but good 80s Jap Fender jazz, and the growly loveliness of the tone came across well without over-emphasis of any part. I can imagine for some gigs, EQ-ing to replicate the tone of more typical bass speakers would indeed be useful as Phil suggested, but I think it will do well set flat for most of the time. Again, a nice tight sound. No boom, and at low volume this suggests real bass might be under-represented, but turning it up to (loud) rehearsal volume gives a (IMO) very well-balanced sound and just emphasises the importance of Fletcher-Munson curves when auditioning loudspeakers for gigging. A relatively brief burst of real power to get the cones moving by a good cm or more peak-peak was very impressive, and suggests that from the performance perspective this cab will easily manage what I want. Bass end didn't seem to be struggling either from fart-out or chuffing. Weight of the prototype is ~7.75kg, quite heavy really (eg half a kilo more than the Genz Shuttle even without hardware, though that's a 12l smaller cab). I hope to lose a fair bit of this with the poplar. Disappointingly several things got in the way that slowed me down and I'm back to Edinburgh tomorrow, so I won't get to the 'real' cabs this time. But I'm hoping to have the ply machine-cut for accuracy and progress further in the near-ish future. User 'Discreet' on here has given me some very helpful advice and suggestions for finishing. Obviously the prototype was a rough bodge with no aesthetic considerations at all but for the real thing I will take much more care. One concern is the softness of poplar compared to birch, so I may yet go down the carpet route to avoid obvious dents. I know from previous cabs that Duratex-type paint won't protect it enough. The polyurea spray is still a possibility. Further suggestions of what to do and what to avoid welcomed. What are other people's preferences aesthetically?

[quote name='pietruszka' timestamp='1325352409' post='1482463'] If the load isn't going to be even then how come 410's work with 115's? [/quote] I suppose they 'work' because the system isn't being pushed to its limits. But a 'typical' 115 will be less loud than a 'typical' 410, and when you crank it up it'll give up earlier as well so you can't get the most out of the 410 unless you bi-amp. If your amp isn't capable of pushing the speakers to those limits then it doesn't really matter. But with a powerful active EQ it'd be perfectly possible to push the Markbass 102 beyond its excursion limits with just 250 watts. The thermal 400w rating is not an issue. (IIRC Markbass use an OEM version of B&C 10HPL64s, and the STD box size is quite generous so these could over-excurse with probably quite modest wattage.) If you play something like a passive jazz without massive bass boost, then you may well be fine with the mismatch as Chris says. If you put the 210 on top then to you playing it will certainly seem much louder, since as well as the extra speaker-age the drivers closest to your ears will each be taking twice the wattage of those in the 410.

[quote name='pietruszka' timestamp='1325351128' post='1482441'] And will the 210 be working harder than the 410 and be more prone to 'farting'? [/quote] Yes, to avoid this you'd need the 210 to be 16 ohms which probably isn't available unfortunately, though perhaps you could source OEM replacement drivers of the correct ohm rating and drop them into the 210 version. Alternatively a 4 ohm 210 cab could be rewired to 16 ohm but this will alter the cab freq response. Before doing this, it might be worthwhile checking the nominal impedance of a single driver in your 410. If they use the same drivers in the 410 as the 210 4 ohm version, then you are sorted. If not, then it could still be done but will sound a little different.

Some pics, prepare to recoil in horror at this cruel parody of woodwork...however the dimensions are within a couple of mm and it'll be more or less airtight apart from the port. The empty box, waiting for glue to dry. I've used some standard wood glue, alongside that horrible (but useful) sticky expanding PU stuff that BFM recommends for the more dubious cuts and the bracing. The shelf port is designed to slide out for trimming/replacement if necessary since I don't trust the box sims for accurate length calculations. [attachment=95969:DSC00955.JPG] Bracing from offcuts, I may add to this, every addition makes a very noticeable difference to panel resonance based on tapping. I've got a lovely C major triad going between the side and two of the top spans currently (perhaps not so ideal!) The unbraced panels rang like a xylophone. Also, I definitely need more practice cutting these baffle holes. Oh how the American DIY builders must laugh, with their enormous 'shops equipped with routers, table saws, belt sanders etc etc. [attachment=95970:DSC00959.JPG] Would you like a little plywood to go with your big airy voids, sir? Actually not as bad as some visible in those braces! Somehow though, despite all the air this cheap ply is quite heavy. [attachment=95971:DSC00960.JPG] Recycling! There are quite a few bits like this...PU glue is good for cheapskate panel bodging. [attachment=95972:DSC00961.JPG]

Phil, that is a fab offer thanks! Basschat is awesome. Prototype is all cut and glued now, but for the poplar I'll think about the options and may possibly take you up on it (if I get that far before I have to head home again). Am in Newton Abbot so Chard is do-able. My dad and I have built a few cabs in the past but usually got the cutting done on his trading estate and/or used mdf which was much easier to work with, hideous allergic responses notwithstanding. I don't think it helped that the ply we used cost £6.19 per sheet from Trago Mills...as you're in the Westcountry I'm sure that'll give you a fair idea of the quality we're dealing with I will put up a couple of build pics if I can for the comedy value.

[quote name='norvegicusbass' timestamp='1325113337' post='1480036'] I fitted new flat strings to my bass and have noticed a distinct metal on metal sound as the string comes in contact with the fret. [/quote] If this is only apparent at the moment of pressing the string down and perhaps the instant you pluck a note, then it might just be because the strings are brand new - if so, as the strings age this will become far less apparent, AFAIK a lot of flats players prefer the sound of older strings. Jamerson kept his on for years IIRC!

There is no way you will have blown all 8 of the drivers...I'd guess they'll be wired parallel too in which case even if one failed the rest would still output. I'd start by assuming it's a problem with the input socket or attached cabling, and rule that out before looking further.

Great band, though Chris I'm afraid the bassist is a great slap player in the Larry Graham mould! Unfortunately the Future Now album is hard to get, not issued on CD I don't think. Universal is a wicked track [media]http://www.youtube.com/watch?v=GH-9lEAjWgQ[/media]

Woo! Finally am getting going on this. Have cut the panels for a prototype from cheap nasty ply, using a circular saw which seems to wander a little so tolerances are less than fantastic to put it mildly. Two cheapy B&Q saws were tried and rejected because the bases were too flimsy and bent pretty much as soon as they were used in anger, this is their third cheapest, not great but will do. Anyway, right angles are for losers. Just off to look for a jigsaw blade as recommended by Phil now, apparently they've got them in stock locally. [quote name='dood' timestamp='1324582636' post='1476007'] I'm interested in this thread as you have chosen Celestions speakers - There doesn't seem to be many DIY builds favouring these. [/quote] I think that's as much to do with the relative dominance of US-based builders on the forums as anything else, the Eminence have represented amazing value for money over there it just doesn't make sense to try anything else. Unfortunately though these Celestions are coming in so expensive even here now with the neo price hike. There's still a few available at old prices (cheaper than you can get a deltalite) but not for long I shouldn't think. Lightweight drivers are becoming a truly premium item again sadly.

[quote name='BH12neil' timestamp='1324947529' post='1478738'] I have just taken delivery of a GK 1001RB-II amp and two GK cabs; a Neo 212II and a Neo 115III. I've wired them up for the first time using the speakon cables provided to find that there is a gentle hissing/hum coming out of both the cabinets, its not loud but it is irritating. I have changed all the leads over in all the various conatations and have tried setting up in the full range mode, none of these actions has illiminated the noise. Now I am new to this sort of kit and I don't know whether this low level noise is normal or whether somewhere along the line there is a problem with either the cabs or the amp. Common sense tells me that the cabs should be silent but perhaps this is not the case. BH12neil [/quote] Background hiss/hum are from the amp, not the cab - though cabs that are more/less sensitive at different frequencies will hide or emphasise it more (typically, cabs with horn-loaded tweeters will hiss more). Hum can be due to mains interference, proper shielding of the bass guitar electronics and in the amp design can help here as can positioning of the kit in relation to interference sources like dimmer switches. If turning the volume down on the bass guitar itself helps, then shielding may improve things. Very well designed/built amps will have much lower self-noise but in general upgrading to more powerful/more sensitive kit you will hear the background noise more. However the output will be correspondingly much louder as well so it doesn't really matter in most live contexts.

Typically reconing involves replacing the entire moving assembly including the coil, so if reconing parts are available then it should be repairable.

[quote name='henry norton' timestamp='1324479462' post='1474770'] Pilot holes can help but aren't essential and just add another process that can go wrong. [/quote] If you don't have a good way of centring the bit, definitely agree! You could try making a 'pilot pilot' hole with the screws (held centred through the body) then deepen this with your pilot bit held straight.

[quote name='Ben Jamin' timestamp='1324250627' post='1472327'] Yeah I've heard they were quite good, but I wasn't sure if it was just a brand-fashion thing 'cause they're all colourful and stuff I'll give them a proper look, thanks! [/quote] I would not trust a pair of headphones designed in consultation with anyone whose mixes sounded like Dre's!

Sounds a bit trite writing this, but a sturdy workbench, clamps and plenty of padding!

Careful, this isn't a US standard, but 'American Traditional' series which was a cheaper US-assembled-from-Mexican-parts bass. The ad copy is accurate about this so fair enough.

As long as you wire the speakers series-parallel to give a total nominal impedance of 8 ohms you should be fine in terms of load.

Hah, thank goodness for stupidity! Hope it all comes back intact

[quote name='klaw123' timestamp='1324396180' post='1473811'] Hi, I have checked the port information, there is a shelf inside which runs down the centre of the cab as a [b]partition in the vertical[/b], it's depth is approx 41cm. [/quote] If I understand correctly (that this runs perpendicular to a horizontal port slot) then this is not contributing to port function. A port shelf would extend the depth of the slot you see at the front. If that slot is just the depth of the baffle you can assume a tuning around 50Hz as I said and the BL10s will work ok in terms of T/S spec. Looking at the response chart for the BL10-200X, it has a peak between 2 and 4k with extension on-axis up to 6k. That doesn't tell you how clean they are, but based on that response I'm sure it'd fall within the accepted range of 'a warm sound with plent of clarity'! Apart from the cost as JT says, might be worth checking the weight of the original drivers compared to the alternatives, you may not like it if it turns out they add a collective 6kg to the cab! If that's an issue then the lightweight neo green label equivalent, BN10-200X, can still be had for under £60 in a few places and will also work in your cab.

[quote name='Ou7shined' timestamp='1324334891' post='1473258'] Perhaps a slight additional tightness to the top end although as with all these things nothing that would be noticed in a band situation. [/quote] Cheers for the info. I switched a BBOT over to a Fender 'deluxe' bridge on my Jap 75, which although not the latest HMV unit was substantially thicker than the thing on there before. My subjective impression was that it made a small difference to the note definition, 'tightness' as you say, but I've never had a BA bridge to hand to try out, and don't fancy forking out to satisfy idle curiosity!

[quote name='4 Strings' timestamp='1324394867' post='1473798'] That's not it at all, Alex. The difference isn't before sounding dirty, the valve amp is incomparably louder. I know what you mean about clean, I only mentioned it as I was not comparing dirty/clipped/overdriven sounds. I'd love to know the reason why. [/quote] Unless you measure the distortion you can't necessarily tell though, especially on a signal like guitar - a 'clean' sound on a valve amp won't necessarily measure as clean. It could just be the gain structure being different where 1 amp is set up to give more output power at lower settings (similar idea to '11 -it's one louder') but I'm assuming you don't mean that. Voicing has a big impact on perceived loudness. EDIT: beaten to it!

[quote name='EdwardHimself' timestamp='1324318723' post='1472989'] sorry I don't have anything to add to this thread, but HULL!!!!! [/quote] I don't know, they've got The Deep, and, err, um... ...do aluminium suppliers count as 'attractions'?

[quote name='Phil Starr' timestamp='1324300026' post='1472684'] Hi Lawrence, you've probably cut your speaker holes by now [/quote] Not at all, thanks very much for the tips! Head down to Devon on Weds and will get going once Christmas is out of the way. Regarding the flattish response, yes that was deliberate based on the fact that I use passive jazzes which themselves tend to have pickup resonance peaks around the same frequencies as a lot of these drivers. I like the sound of the basses (and further tweak them based on how they sound) through semi-decent headphones. My aim is to have a solid tone but one where the 'cabinet' sound isn't dominant, so switching basses will result in a more useful tonal change. As an example, rather than use the speaker for that peak I could switch the pots on, say my jazz with Model Js (internal parallel wiring) from 250 to 500k and the Hi Z resonance peak will increase in magnitude but I won't be stuck with it for my other basses. I really want these cabs to function as acceptable 'all-rounders'. In terms of low(ish) bass, I think there is leeway in the design to tweak the tuning slightly higher to firm up the response around 100Hz (which at the mo is a couple of dB down) at the expense of lower down, I'll see how I get on. For comparison I can very easily change to an Eminence Deltalite in this cab which will do roughly the same thing as well as add that peak. What I think is notable is that multi-driver cabs without horns will typically roll off in that 1-2k-plus region anyway due to reduced coupling once driver spacing gets significant v wavelength. Looking at online graphs of an Ampeg fridge and a fair number of 'classic' cabs, they all peak in the mid-bass/low mids as you'd expect. If I was building a pair of 2x10s to use together I'd likely choose a driver with more of a rising upper-mid response at the expense of low-mids to counter this, for a similar overall voicing.

[quote name='Mr. Foxen' timestamp='1324326723' post='1473109'] Will need the depth of the port, there's probably a shelf inside. [/quote] Might not be with a port that size, if it's about 140 litres inside then tuning should be around 50Hz just with 18mm baffle thickness. Those Celestions should work just fine in that cab, but you'll get port chuffing long before the speakers themselves run out of capability at 50Hz. In practice this might not be an issue, depends on your bass/sound and this would likely have been an issue when you pushed the cab before anyway. Most significant issue is probably how similar the freq response of those speakers is in the mids/highs to what you had before, but it's hard to know without a response chart for the old speakers.

[quote name='Ou7shined' timestamp='1324291704' post='1472520'] The big drawback with the BBOT is that it allows very little lateral correction as your saddle grooves are pre cut and not adjustable. [/quote] The old spiral groove bridge saddles were better in this regard. Out of interest, did you notice a tonal difference on the 70s RI after the change?

[quote name='LawrenceH' timestamp='1324329834' post='1473175']Headless bass necks are light and stiff, these resonant frequencies are correspondingly higher, in the case of the ones causing dead spots hopefully nicely out of the way of the fundamentals! [/quote] Oh yeah, thinking about it I realise that I didn't explain this fully at all. The dead spot should be a function of the fretting position along the neck in relation to the mass distribution, so even if you kept the overall mass constant, altering its distribution would alter the way the resonance interacted with the string. Chopping off the headstock should tend to shift dead spots further up the neck.