LawrenceH

[quote name='Bill Fitzmaurice' timestamp='1385679948' post='2291209'] This is a chart of the Ampeg SVT driver, ported in blue, sealed in red, in the same net volume. Of course the gross volume of the ported is larger, to account for the duct, but the increased sensitivity makes that worthwhile. The ported does have a higher roll off slope below 30Hz, but that's hardly of any consequence. [/quote] Your own example is a good one for showing exactly what I'm talking about. Yes, the slope rolls off steeper below 30 just as physics says it must. With this particular example the increased sensitivity above that means the group delays between the two cabs will diverge at a much higher frequency ie the transient response of the ported cab will be poorer. The only way of getting it to perform equivalently, above 40-odd Hz, would be to reduce the cab volume. And you'd still see it peak abruptly below this.

[quote name='Bill Fitzmaurice' timestamp='1385678796' post='2291179'] That doesn't mean one cannot realize the same result with vented and sealed, just that one must possess the necessary design skills to do so. [/quote] Yes, it does mean exactly that. Unless the 'laws of physics' you so humbly equate yourself to are markedly different to everyone else's. You can get it the same in a limited bandwidth, which is what I said at the beginning. You can't get the final slope of a ported cab below resonance to roll off at 12dB/oct no matter how many magical beans you buy from mysterious old men you meet on the way to speaker markets.

[quote name='Bill Fitzmaurice' timestamp='1385672538' post='2291085'] You can. [/quote] No, you really can't and someone with a quote about the laws of physics in their sig should be clear on this. The sum of the driver/port below resonance will be a 24dB/oct slope. Always. All you can do is play with the knee, and push the 2nd-4th order transition so low that the peak is outside the effective bandwidth of the cabinet. Which is good, and still offers worthwhile benefits over an equivalent sealed cab in terms of size (although this can easily be eaten up by port size/length requirements for high power operation) and subsonic excursion. But it's not actually the same. [quote name='Bill Fitzmaurice' timestamp='1385672538' post='2291085'] I don't know why you'd want to, but it's not all that difficult, if the driver specs are amenable. [/quote] Because a lot of people like the sound of the transfer function of a sealed cab between, say, 0.5 and 0.7. If you're not concerned about cone excursion, then considering the sealed cab versus a (bandwidth-limited) identical ported cab, the former is extremely easy to build and avoids certain problems with port/room placement, port resonance and midrange leakage. These latter I'd agree can be made a very small problem, but a very small problem is still not as good as no problem, may as well keep it simple if it suits the application.

I am always puzzled when I see people say that you can design a ported cab to give the LF response of a sealed cabinet, because of the inherent phase relationship of the port and driver around and below resonance where it has to transition to a 4th-order rolloff. Closest you can do as far as I understand it is to tune very low so the more dramatic effects on system phase are out of bandwidth. Audibility is argued but a lot of us subjectively prefer the sound of a sealed box or these deep-tuned ported cabs, despite the fact that they don't make the most of the woofer in terms of raw in-bandwidth output level. In hi-fi, I also think mid-range leakage from ports can be a difficult issue to solve completely satisfactorily as well. For high power PA/bass, I think the cooling advantage offered by ports probably does translate to a real-world benefit. Based on spec alone I'd take the Barefaced over the Matamp any day of the week...but that's because the Barefaced uses much better drivers (sorry but the Matamp ones are nothing special AFAIK). Plus, I'm not absolutely sure but since the Barefaced driver has extension to spare, I suspect these cabs are tuned unusually deep so minimising the disadvantages of a ported cab wrt transient response. The Matamp versus another more run-of-the-mill ported cab...a tougher fight, I suspect I'd prefer the sealed cab.

[quote name='Iheartreverb' timestamp='1385564125' post='2289691'] I'm saying I dont want the max output (and gain it brings) but cant hear myself or be heard any other way. [/quote] You may fully understand this already but just to be clear, maximum output volume is not the same as high preamp gain. The amplifier section has a maximum output determined by a (fixed) gain multiplier and the rail voltage. You have no control over these and in terms of peak output it doesn't get louder than this whether the signal is clean or dirty. All you can change is the preamp signal and the degree of attenuation of the preamp signal before it hits the amplifier section. Sometimes you get a problem where the preamp peak clean output doesn't allow you to get maximum voltage swings from the amp even with the master volume (the amp input attenuator) on maximum (ie zero attenuation), but that's normally more of an issue with a separate preamp driving a PA-type power amp and this is the situation where a clean boost inserted at the right point in the signal chain can help. The preamp is normally where the obvious 'dirty' gain is, driving valves, FETs, whatever into saturation and clipping. Dirty sounds louder because the average (but not peak) signal level is increased, and it adds extra harmonics to the signal. A 'clean' compressor also increases the average signal level in relation to the peak, but in a way that doesn't sound so obviously distorted. The only ways you can get more peak volume are by using a more powerful amplifier or by adding extra speakers. But an 810 driven by a hundred plus watts should be capable of absolutely deafening volume, which is why people are suggesting you consider your EQ and that of the guitarists. Your ears hit their limits before that kind of kit will unless you're feeding it lots of subsonic signal. If the main signal content of the sound you like is in the same zone as the guitarists', then whenever you are playing at the same time you will get in each others' way. There is no way round this, but sometimes a small change of frequency centre is all that's needed, not necessarily anything like as drastic as switching to neck pickup alone. A pickup change, if it helps (and it may well), will do so by changing the sound of the bass much like EQ - a pickup is a filter, same as an EQ module. Hence in a studio, with powerful enough EQ and compression it's possible to get close to all sorts of pickup sounds and configurations with a single input signal, which is more-or-less how Line 6-type emulations work. It's a lot easier to troubleshoot this kind of thing in person so if you know anyone with experienced ears then get them along to a practice.

[quote name='Iheartreverb' timestamp='1385543610' post='2289398'] Yes the middle position is both pickups together although I dont blend them and just have all pots on full. [b]It's true that it sounds very guitar like at this point[/b] but this tone through a clean mid heavy amp is exactly how I want it to sound....just louder. [/quote] Worth quickly checking the pickup phase given the volume drop you describe...but I don't know why or how you expect this to cut through against two other guitars through thick-sounding setups. When two or more very similar sounds play together, then the brain really struggles to pick them apart and typically the one that is quieter (even by a tiny bit) and/or starts later gets lost. This is called frequency masking and temporal masking respectively, and is how mp3s are able to throw away 90% of the sound and still sound kind of good. When you mix a band live or in the studio and you want everything to be heard, then you have to find frequency pockets for each voice to sit in. Think of volume across the frequency spectrum like water in a bucket - once a 'bucket' is full, then it's full - you can't just add more water, you can get a bigger bucket but you just hit the same problem only everything's louder (wetter? ). [quote name='Iheartreverb' timestamp='1385543610' post='2289398'] Surely the only way for me to be heard isn't to play with the exact opposite to the sound I want? You wouldn't say this to a jazz or soul band..."yeah just grind the hell out of the amp". Plenty of bands I like achieve this balance and live this shouldn't be a issue as everything will go through a sound desk and pa so the mix will be there. Its just getting a practice tone right. [/quote] If you are playing a sound that's incompatible with the other sounds, then something has to give. And from a mix point of view I can only do so much with the sound a band gives me. If the sound is s**t to start with I can't magically undo that, only mitigate. Loud amps on stage make this problem a lot bigger because I can't suck bad sound out of the air. The bands that achieve the balance you describe normally do so by having instrument sounds that in isolation would each sound a little rough, dull or thin, depending on which area(s) of the spectrum they focus on for each. Heavy but very expensive compression is the other part of the solution in the studio, keep everything at practically identical volumes to minimise the masking effect. Take your example of a jazz band: jazz guitar voicings often leave out the root note entirely, plus they will comp on a rhythm with lots of gaps, Leaves plenty of room for other instruments to fill up both in terms of frequency and in terms of time. [quote name='Iheartreverb' timestamp='1385543610' post='2289398'] Is there anything else that could help such as a clean boost in my chain that will increase my input before power amp? [/quote] Without hearing you these suggestions are all guesses, based on previous experience of common problems - but if the problem is a mix issue then by going louder you will just shift the problem to another instrument, and probably break each others' ears in the process. Unless you're saying that your output is so weak that you can't get the amps close to maximum output even with the master volume on full, then all a clean boost will do is make it easier to overdrive the preamp section that you say you're trying to avoid doing.

[quote name='Iheartreverb' timestamp='1385505508' post='2289200'] I'm already using a compressor quite high, this focuses my otherwise very low output. With that you said about finding a place (tone/frequency) to be heard, that's what I've done. Neck pickup, gain. But this isn't the overall tone I want, as described [/quote] It really does sound like a mix issue with the guitars sitting in your space in which case it's not you, it's them - but possibly also a preference for quite a mid-scooped sound from the Ric if the middle position corresponds to two pickups blended (I'm not familiar with Ric settings)? Mid-scooped basses are another challenge to fit into a mix because the mid-range is where most of the character of the sound is. The neck pickup alone, especially into a typical Ampeg-style 810, gives you a lot of upper-bass/low mids, this region typically gets wiped out when you blend pickups with upper-mids/treble becoming more prominent instead. I notice you're boosting your mids a bit already, what is your amp? It may be the frequency centre is not very suitable, or if it's a Fender-style tonestack then you will still effectively be cutting mids with this setting. Regarding the compression, do you have much control over attack/release settings, and can you change where it sits in the signal chain? With enough control a good compressor can be something of a magic wand. I'd suggest experimenting with a far more hyped, aggressive version of the sound you like in isolation, exaggerating any clanky upper mids and making sure the compressor is keeping their level up for longer - it's amazing how in context something like this will sound 'smooth and rounded', whereas what really sounds 'smooth and rounded' listening in isolation just gets totally buried.

412s can get very loud, but it's not just a volume thing. The Marshall sound is dense and can cover everything from around 100Hz right up to 4kHz, ie all over the bass guitar. You need to find the tonal gaps in there (if there are any) and boost those, or (better) get them to cut a hole somewhere for your bass. Often guitarists boost the bass/low-mids too much to get that thick chunky sound, great on its own but wipes out the bass in the mix, and it sounds better overall if they get a tone that's a little thin on it's own. When I do sound, Marshall-type driven guitar tone gives me the biggest difficulties with the mix 9 times out of 10. Especially if there are two of them, and especially especially if the guitarist comes with ego attached, which with Marshalls they usually seem to :/ Also, those Marshall overdrives give a very compressed tone. You may want to compress the bass to match, or you'll find the note decays too fast in comparison.

It's arguably worth it if the amp is quite low power compared to the speaker thermal handling, and you're just after a little more clean headroom where a couple of dB can make all the difference. That said there isn't an obvious 4 ohm equivalent of the 15" driver in your cab. Faital 15PR400 is probably closest but is still a dB or so quieter per watt in the low mids and is voiced differently, lacking the upper-mid 'bump' of the current driver so it'll sound a bit smoother, but a little less prominent in the mix. If you like the current sound but want more heft, adding another Compact is definitely the best solution.

[quote name='stingrayPete1977' timestamp='1384876866' post='2281753'] I have noticed that the resident experts on here are quick to tell everyone not to use mismatched cabs even though a 1x15 and 2x10 was a very popular rig for a long time yet the most popular mismatched rig I see now is normally some kind of Barefaced mountain of various cabs piled up with some on their side etc? [/quote] That's a different issue, we're talking running in series here - the impedance curve mismatch between the dissimilar drivers will Mess S**t Up. I agree that the theoretical problems of running different speakers (in parallel) can be overstated compared to real world situations. Sometimes it messes up the bass end, but even then you might not notice! The room will often do a lot more 'damage' to that region.

Some great discussion here! Best thread on speaker design I've seen in ages. I agree with others about the limitations of bracing, and the limited utility of pole cross braces. Pole braces are good as an easy fix for limited bandwidth subwoofers and not much else IMO as they only effect certain types of modal vibration. There are some models using FEA that have been discussed online, they have their limitations but they're useful for visualising the different bending modes that contribute to various resonances and making the point that braces themselves must be sufficiently stiff to be useful. See here if interested: [url="http://www.audioholics.com/loudspeaker-design/detailed-look-proper-loudspeaker-cabinet-bracing/finite-element-analysis-part-i"]http://www.audioholics.com/loudspeaker-design/detailed-look-proper-loudspeaker-cabinet-bracing/finite-element-analysis-part-i[/url] Also it's nice to see the distinction being made between the effects of adding rigidity and damping, and the effect of varying Q regarding the latter (eg uneven panel sizes). I like to see in terms of energy conversion efficiency. With increased rigidity you are increasing the overall energy converted to sound, whereas increased damping is converting more of that energy to heat. I'm not sure where the practical limit sits, but conceptually I favour stiff and as light as possible, to maximise sonic efficiency and reach a point where the resonances are at a high enough frequency that first there is a lot less overall energy to excite them and second damping becomes more effective. Stevie, I'd be very interested to hear more about your K12-alikes. I'm a big fan of those speakers, on another thread a while back I speculated that the moulded cabs sound decent (IMO) because the Q of the material is lower than eg wood - but that alone won't compensate for the loss of efficiency and so I'd guess that the wood ones sound 'tighter' and measure louder. I've also been building some PA cabs, using 9mm birch ply and quite extensive shelf and column bracing. I hope that these will still be pretty stiff (I couldn't lift them if they were 18mm birch! I want to try birch-faced poplar or similar), will get to the point of testing in a couple of weeks.

Glad to hear it has worked out ok, sounds like your experience has been similar to mine. For the stains I'm not sure, but something like xylene might clean them up a lot without having to take any material away- bit late now though sorry!

[quote name='Phil Starr' timestamp='1384328395' post='2275202'] Thanks Lawrence, I've pretty much decided to take your advice and I've started a test with one of the smaller dinks using my daughter's nail varnish. I think I might try superglue as well. Can't believe i'm experimenting on a £1000 bass! [/quote] Haha I only did it myself because I knew I could reverse it if it all went belly-up! Good luck

[quote name='Phil Starr' timestamp='1384246544' post='2274302'] Mine is definitely Poly of some sort, acetone doesn't touch it at all. You can get the poly lacquers easily enough from car parts shops and also Axminster Power Tools which does a good mail order service. The trouble is knowing which poly finish you are dealing with, Some are two part some single part, some solvent based and some water based. I'm guessing polyester polyurethane and acrylic. The other problem is that they vary in solids content and they are shy about this too. Nitro cellulose is good because the lacquer redissolves in the solvent and then cross links with the new lacquer so it is a complete repair. I'm guessing there is no way of cross linking polyurethane with new polyurethane, polyester with polyester or acrylic/acrylic. That is assuming I can find out what finish I have, I guess an email to Fender might tell me. Having said that I've successfully drop filled dinks in furniture with poyurethane varnish, which is slightly yellow due to the alkyd resins in the varnish. [/quote] Acrylic redissolves like nitro (at least, the rattlecan stuff does) - Fender stuff is definitely a 2-part catalysed finish that you can't redissolve, very nasty to spray but tougher than the poly you can buy in consumer cans or 1-part varnishes (or any other finish for that matter barring probably epoxy) The superglue on mine glossed up fine with wet'n-dry up to 1500 followed by rubbing compound, though I imagine the drop-filling with varnish would work at least as well, especially if you want a bit of yellow tint. If it were me I'd just go with whatever I had a pot of to hand!

[quote name='wateroftyne' timestamp='1383909931' post='2270641'] Not a fan, then? [/quote] Not got anything against them as I've not heard them, and the design is pretty tried and tested so I fully expect them to work well. Just that those driver combinations won't tread any new ground beyond where fEarfuls and indeed earlier generation Barefaced cabs could go (assuming I'm right - Eminence are listed as the driver suppliers so I think I am, and I'm not aware of Eminence moving to a new gen design) and indeed borrow an awful lot from them, so I find it funny that people are getting so excited about them. The Aguilar cosmetic clone does seem a little cheeky too. Of course there might be voicing differences but these are likely fairly minor because the drivers themselves limit your options in terms of sensible crossover points. If that still sounds too negative, let me reiterate - I expect these cabs to be very capable performers and for some the cosmetic options might make all the difference

I should say too, although I've stripped a polyester-coated alder body successfully using gentle heat, I definitely wouldn't fancy stripping a urethane-coated maple neck - hard to do mechanically without tearing into the maple and the polys are very resistant to chemical stripping in my experience. A job for a pro I reckon

The Fender finishes are typically a catalysed polyurethane (or polyester for cheaper instruments). As such you can't repair them like with nitrocellulose where you just add more and the fresh solvent does the work of blending it in, because the curing is irreversible. However I had quite good success making repairs on a dinged polyurethane-coated natural ash finish Fender by just flaking away the damaged area with a razor blade and then filling with superglue, before sanding and buffing. It was near-invisible in places but on the neck there was a slight yellow tint which the glue didn't replicate, at least not consistently (some did darken up a little, I think moisture is a relevant variable here). However the feel was perfect once rubbed down, which probably mattered more for the back of the neck, and the difference was fairly subtle. Superglue is soluble with acetone, which does nothing to a catalysed poly finish so you can always try it out reversibly. Bear in mind it'll eat through nitrocellulose and acrylic happily, as well as neck binding, so worth a quick double-check!

I'm sure they are great cabs. The options with mid driver look suspiciously like eminence alphas/alphalites. Guessing it's kappalite LFs for the neo woofer options too... is it 2009 again?

This Celestion might be worth a look for a screw-on solution, it's pretty new to their range which might be a good thing in relation to previous generation units: http://www.thomann.de/gb/celestion_cdx1_1010.htm It's another with a polyester diaphragm, from what I've read these reportedly sound a bit less harsh than a lot of titanium designs when driven hard, certainly that correlates with my subjective impression of the 18sound - n of 1 though!

[quote name='Phil Starr' timestamp='1383780972' post='2269185'] We always had limited gain before feedback too because of the peaky response. It is standard practice in hi-fi cabs with 2nd order crossovers to reverse the tweeter because of the phase shift in the crossover, so I tried it and yes it sounds better both in an A/B comparison and in a live performance. What did you do about inductors? I found them hard to source and expensive and in the end had them wound by IPLacoustics. [/quote] I will have to check the wiring in mine - perhaps they are already wired that way! I've quite often used them alongside other people's monitors and they have almost always given fewer feedback issues, and by ear the response isn't so much peaky as one broad midrange hump. You are convincing me that I should measure them properly when I get the chance. Inductors were Jantzen from audio-components.co.uk, there were other sites that listed cheaper but the postage for a small order was prohibitive. I used air core on the high-pass which was around 0.5mH, and 'p-core' for the woofer at 1.5mH. £20 for 2 of each, and another £30 for the other bits so £25 per crossover. I wish I had a better source of these bits!

[quote name='Phil Starr' timestamp='1383724992' post='2268072'] Thanks for this Lawrence, one I hadn't looked at. It has quite a droop in the upper frequencies but that could help in a monitor. You are happy with the sound and clean mids are what a decent monitor needs more than extreme highs. [/quote] The extreme top end of one of mine (10k and above) is quite ragged, doesn't give a smooth roll off at all, I did wonder about sending it back but it really doesn't seem that important live. I often just filter out everything in the monitors above 10kHz anyway and no-one ever notices! I used series-parallel resistors in the crossover to balance it up as much as possible, I like that way of doing it because resistors are cheap [quote name='Phil Starr' timestamp='1383724992' post='2268072'] Did you see my post about the yamahas? I've reversed the polarity of my horn drivers in my S112's which has knocked the nasty mid peak back a bit, really cleaned up the vocals and tamed some of the feedback problems. [/quote] I didn't see this no, I'll have a look. I have the IV series and I don't think the drivers are deltas, maybe betas? Been a while since I had them apart though - classic chipboard construction IIRC but with a lot of wadding for a commercial cab. The mid-bias is colourfully present but they have always been good performers in terms of volume before feedback, and the region where the boost is seems to be both quite broad and quite useful for a lot of vocalists to hear themselves. I built the new monitors with a similar form-factor to the Yams as I find it a useful one, but using braced 9mm birch. At some point I might scrap the Yamaha cabs and recycle the drivers, if this happens I'll measure them and tweak the crossover accordingly. The current one looks pretty cheap and cheerful; even with a 2nd order and no Zobel or resonators, and being a bit stingy on component ratings, my design was not that cheap unfortunately. But whatever compression driver you choose you face this same problem in my experience. Time alignment is a bloody pain as well with deeper PA horns in passive designs. Active DSP all the way (if only)

Hi Phil, I don't know about screw-on drivers, but I recently salvaged a pair of decent Celestion cast woofers from PA cabs we built in the late 90s and recycled them into sealed box stage monitors - for tweeters I used the 18sound XD125 (as used in fEarfuls) because they are dead cheap for comp drivers+horn, and was very pleasantly surprised with the results. Tried them out doing sound for quite a big-name vocalist who has discerning ears and they were enthusing about their monitor mix afterwards. They are MUCH nicer sounding than both my dog-eared Yamahas (Eminence ASD1001s into Yamaha custom CD horn - mid-biased so they cut through well as vocal monitors but it is a coloured sound) and my JBL Eon G2s (JBL 2412H-1" I think? A bit trashy up top), and a definite step up from the ubiquitous Em APT80. I went with an acoustic crossover of ~2.4k, 4th-order LR (electrically 2nd order asymmetric) - a bit higher than the ideal for 12" woofers so the response pinches in a little around 2k horizontally, and gives an alarming notch in the vertical polars. In practice thanks to the steep slopes the subjective sweet spot is quite wide (ideal dispersion characteristics of stage monitors is a whole other topic, I notice that many high-end designs use relatively narrow-directivity horns, something I'm not a fan of for smaller gigs). I did use measurement and modelling software to design the crossovers and they measure pretty flat throughout the crossover region; if I redesigned the crossovers for the Yamahas it might be a fairer comparison, but I can say overall they are very smooth-sounding speakers, relatively free of coloration in the vocal range. If I hadn't already had the woofers I'd have gone with 10s or even 8s, I think this tweeter would make a superb little vocal PA cab coupled to a mini woofer. One final thing - my understanding is that mating drivers, especially screw-ons, with random horns can cause issues due to resulting abrupt discontinuities in the flare profile. Apart from price this is the other reason I chose a driver+horn combined solution.

The main thing to watch for when using a decent power amp is that your preamp is up to scratch in terms of output level - pro power amps are designed for pro output level, they usually state the input sensitivity as part of the spec. Strangely, lots of bass preamps don't seem designed to match these. If you get it right then a pre+power amp combination beats most dedicated bass amps IMO.

The Bose system is a nice concept but if it's similar to their previous products, and user reports suggest it is, it is let down by component quality/power when you take it beyond a certain point. The HK elements system is an equivalent but made with good components, and the Fohhn Linea is the idea taken to the ultimate quality and power level. But you will still get feedback beyond a certain point with speakers firing into the mics, directivity control and high fidelity reproduction help a lot but they can only do so much, they're not magic - a conventionally-placed front-of-house system with high quality side-fill monitors is probably a better solution for those cases.

Alex I vented at you a while back for talking in marketing-speak rather than the more expansive discussions of old. I'm really pleased to see these new gen cabs announced, and REALLY pleased to see a decent discussion of design elements and philosophies on your site, which actually openly encompasses the limitations of the older designs. E.g. the reasoning for the change to high-quality 2-way is something I definitely agree with. My experience has been that other drivers had become available off-the-shelf that usefully surpassed the performance of the Kappalite series, but it looks like you have an OEM model that leapfrogs these nicely. I've not previously thought BF (or any manufacturer) worth it for me compared to DIY, but that's not the case any longer. I think I'll be buying one at some point (though if you wanted to sell me a driver even at a nice premium I'd be a happy customer ) EDIT: Also, the price looks very fair on these, I'm really impressed all round