stevie

[quote name='oldslapper' post='1046545' date='Dec 3 2010, 04:46 PM']Stevie.........Dorset bass bash next summer...... [/quote] I do hope you're going to organize another one. I'll be there!

[quote name='Phil Starr' post='1044858' date='Dec 2 2010, 11:37 AM']I'm sorry to disagree with you but this is a bit silly.[/quote] It's not only silly - it's complete bollocks. The output from the vent is delayed in time compared with the output from the front of the speaker cone. Thus, a reflex speaker cannot by definition have a transient response as good as that of a sealed speaker - because that delay is always present when there is output from the port. [url="http://en.wikipedia.org/wiki/Bass_reflex"]http://en.wikipedia.org/wiki/Bass_reflex[/url] Let us listen to what a real speaker designer has to say about this, shall we? Cue Mr. Siegfried Linkwitz. The name may be familiar to you if you have an interest in loudspeaker design. ([i]On his decision to use a sealed cabinet for his state-of-the-art subwoofer[/i]) - "I did not consider alternate approaches to subwoofer design as [i][b]acceptable for meeting my goal of accurate sub-bass reproduction[/b][/i]. This includes [b][i]vented[/i][/b], passive radiator and acoustic bandpass woofers. They all rely on [b][i]resonant energy storage[/i][/b] to increase efficiency and to reduce size. ([i]On his choice of a sealed alignment for his Pluto speaker[/i]) - "Finally, most box speakers use [b][i]vented [/i][/b]enclosures which means [i][b]stored energy[/b][/i] to increase otherwise insufficient or distorted bass output. PLUTO+ is sealed with a Q = 0.5 roll-off at the low end of its frequency range for [b][i]optimum highpass transient response[/i][/b]." I'd be very interested to see anyone attempt to prove Linkwitz wrong on this. Over to you Mr Fitzmaurice - or are you too busy designing loudspeakers

[quote name='bumnote' post='1046226' date='Dec 3 2010, 12:29 PM']To add to the debate, I have a mini 1x15 and it doesnt sound particularly nice to me, I can only describe it as Boxy whatever that means, while I love the 4x8 for its compact size and its sound[/quote] I have two of them in the garage, which I am very slowly converting into 12" cabs. I posted some measurements of the cab on here a while ago showing a (not very nice) bump at 100Hz. You could try pulling that frequency down a touch with your eq. I'd equate 'boxy' with a problem at a higher frequency than that. There is a very good chance that lagging your cab with wadding will reduce the boxiness, because boxiness is the typical sound of a box that's not lined IMO.

[quote name='ezbass' post='1046421' date='Dec 3 2010, 03:00 PM']I phoned Ashdown and bought the new neo versions that they fit in the Superfly cabs.[/quote] From what's been posted on here, Ashdown replacement speakers are quite good value. As we know, some bass companies charge the earth for spares. I would definitely consider that an option. The internal size of the Mini 15 cab is 55 litres. At a rough guess, that would make the internal size of the combo, what - 40 litres? That's quite large for a 10", and larger than the Celestion neos like to see. If you want a Celestion, you'd be better off with a 12". The Eminence Deltalite 2510 works better in a large box. The downside of that driver is that is shrieks like a banshee at 2kHz. Some people equate that with clarity, but there you go (and you can always pull it down with the graphic). If, as you say, the purpose of this exercise is to cut down on the weight of the combo, it might not be as successful as you think (as Bumnote has pointed out). A Deltalite neo weighs 2.1kg. The ceramic magnet Celestion BL10-200X weighs 3kg, and I would suspect has a larger magnet than the Ashdown driver you have at the moment. Before you spend any of your hard-earned cash, I'd suggest you weigh the Ashdown driver.

John, are you sure it's a 10"? I checked the website and they don't seem to have made any 300W ABM combos with 10s. Do you have a model number?

[quote name='4 Strings' post='1035918' date='Nov 25 2010, 09:22 AM']What do you think?[/quote] You're right about the mach levels being very conservative on that calculator, but that's no bad thing. It's good to see you now have a handle on what's going on. I think you're well on your way.

[quote name='Bill Fitzmaurice' post='1035183' date='Nov 24 2010, 03:28 PM']Ask Galileo.[/quote] Have you spoken to him lately, Bill? How is the old guy?

Only if your willy is vertically aligned!

[quote name='jonthebass' post='1035185' date='Nov 24 2010, 03:32 PM']If it helps I'm well happy with my 2 Barefaced Compacts and they do a most excellent job! I recommend Alex's gear highly...[/quote] There's a man who'll give you a straight answer to a straight question.

[quote name='Bill Fitzmaurice' post='1035183' date='Nov 24 2010, 03:28 PM']Science does have a tendency to win out over dogma, though sometimes it takes a while. Ask Galileo.[/quote] Yeah, Bill. You and Galileo are one of a kind.

[quote name='Phil Starr' post='1034867' date='Nov 24 2010, 11:00 AM']Stevie, if you ever fancy a trip this way I'd love a second opinion on my cabs.[/quote] You're not all that far from me, Phil. Sounds like an idea. I'd be very interested to hear what you've concocted. You can buy me a pint whilst we're at it

I think Phil's sealed cab idea is worth a try. I'd go with rear porting personally, but 4 Strings himself is the only one who can say whether a sealed cab is useable. It might also be a useful interim solution that can be easily and quickly implemented – certainly quicker than building another box, which he has said he doesn't want to do.

That's a nice bit of lateral thinking and certainly worth a try, as it will completely bypass the port turbulence problem. Here is a comparison of the performance of the sealed and ported versions of this cab (yellow is ported and pink is sealed): Notice that the sealed version loses quite a bit of sensitivity between 60 and 200Hz, which will make the bass sound thinner. A tweak of the graphic eq could compensate somewhat. The downside of the sealed version is that it will not go as loud as the ported version between 50 and 100Hz. It could be loud enough though.

Hi Dominion, I assume you mean replacing rather than reconing. The two leading budget brands of speaker suitable for bass guitar are currently Celestion and Fane. I suspect that Fane currently has the edge in the value-for-money stakes. Eminence is mentioned a lot, but their stuff if very hit and miss. Phil Starr, who is well informed about these matters, tried out some of the Fanes not long ago. You might like to PM him, as I haven't seen him posting for a week or two. Celestion makes a number of ranges specifically designed for bass guitar. So you are unlikely to go wrong by choosing from the Celestion Green (in preference to the Orange) bass guitar range here: [url="http://professional.celestion.com/bass/green/index.asp"]http://professional.celestion.com/bass/green/index.asp[/url]. The neo drivers are more expensive than the traditional ferrite magnet ones but offer the advantage of lightness, which is probably irrelevant for your purposes.

[quote name='LawrenceH' post='1033098' date='Nov 22 2010, 07:35 PM']I didn't really want to go down this road because originally I was only making a throwaway point that ported cabs are not without compromises of their own, but I dislike such a didactic and obfuscating response to a point as I originally got (especially when it effective diverted from the main thrust of my argument).[/quote] [u]Description of Red Herring[/u] A Red Herring is a fallacy in which an irrelevant topic is presented in order to divert attention from the original issue. The basic idea is to "win" an argument by leading attention away from the argument and to another topic. This sort of "reasoning" has the following form: 1. Topic A is under discussion. 2. Topic B is introduced under the guise of being relevant to topic A (when topic B is actually not relevant to topic A). 3. Topic A is abandoned.

[quote name='4 Strings' post='1034384' date='Nov 23 2010, 08:29 PM']On the link to Falcon Acoustics there's an 80mm version with bell mouths. I'm thinking of two of those.[/quote] Yes, I agree they look good. Unfortunately, the design constraints on your cab are so tight, that two 80mm reflex ports would be too much: the combination of the flaring and the extra diameter would require a port length of 300mm (or more). However - and the choice is yours - a single 80mm flared port (170mm long) would be noticeably better than what you have now (because the flaring at each end helps reduce turbulence), but not as good as two 66mm ports.

I think we have an echo in here. Follow this link for a JBL cab that is just a bit bigger than yours: www.jblpro.com/pub/obsolete/4646a.pdf. It's 34 litres compared with your 28 litres - a difference, but not a deal-breaking one. It contains a JBL 2206 driver which models very closely to yours in the same-size box. You'll notice there are two 70mm ports at the front. JBL built thousands of these and it is a well-proven, compact sound reinforcement bass cabinet, specifically designed to accept bass boost. JBL fitted this particular 12" driver to smaller cabs (the Soundpower 1725 was only about 20 litres if I remember correctly) as well as to bigger ones. I happen to have one of these cabs at home - it's a nice size for tucking under the piano. I have the original JBL speaker but have also fitted a number of other 12" drivers, including a Celestion neo, which is in there at the moment and which sounds great. You are, of course, free to build another cabinet to put your Beyma into as Bill seems to be insisting ad nauseam that you do. But if, as you say, you're happy with the sound of your present cabinet, adding a second port will allow it to go louder before the onset of nasties.

I did a similar conversion with a 2 x 10 Laney cab not so long ago. I swapped the drivers for better ones and put a 4" rear port in the back where the crappy input panel had been. I then fitted a Speakon input socket on the back. It completely transformed the cab, as its new owner will testify. And it looks professional.

You're thinking along the right lines. What I suggest you do is this. Close up the hole at the front of the cab using a piece of plywood (or put the tweeter back in). Then fit two of these ports to the back of the speaker: [url="http://www.falconacoustics.co.uk/cabinet-parts-accessories/bass-reflex-port-tubes-loudspeaker-grille-mounts-dowels-calculation-sheet/bass-reflex-port-tube-standard-reflex-66mm.html"]http://www.falconacoustics.co.uk/cabinet-p...eflex-66mm.html[/url] The theory says that you should leave a gap equivalent to the diameter of the port between the end of the port tube and the back panel of the box. I'm not sure quite how rigidly you need to stick to that, but the ports are adjustable in length anyway - so if you want to experiment you can. Moving the port close to the back panel will drop the tuning slightly but will also cause turbulence. The ports I've suggested are just under 3 inches in diameter and will therefore give you a usable tuning at around 170mm long while still maintaining a reasonable vent air velocity. The benefit of doing it this way is that the cabinet will still look good when you've finished. One port at the front and one at the back would be a bit of a bodge.

[quote name='Bill Fitzmaurice' post='1032706' date='Nov 22 2010, 03:00 PM']There's nothing the least bit magical about sealed cabs. Most cabs in the 60s were sealed not because they sounded better but because most of the drivers available didn't work any better in vented alignments. Designers/manufacturers who still create sealed cabs don't do so because they're better, they do so because they sell, mainly to customers who think there's something inherently better about the tone of a sealed cab.[/quote] I'm not sure what cabs in the 60s has got to do with anything, but here's one of those customers who thinks there's something inherently better about the tone of a sealed cab. "[i]What are your thoughts on closed box vs ported for mastering in a properly treated room, especially with bass heavy music?[/i] This is a real sore point with me. As far as I'm concerned, every ported speaker I've ever heard, even the ones purportedly optimized for perfect Thiel/Small performance, has "looser bass" and usually some kind of hidden or obvious resonance and often compromised dynamics. …… And since mastering should employ an absolute reference speaker, then ported has to be out, unless someone out there can name an exception to the rule that I have not yet auditioned. People come from miles around to listen to and marvel at my system, which has been quoted as having the "tightest, flattest bass around". My Reference 3As are ported, (which I used before I moved to the Lipinski plus JL sub), and demonstrate to me time and again that the 3As definitely were an interim mastering solution. They now sit in the alternate listening room to prove to one and all that you can easily manufacture artificial bass with a port! Bob Katz