RichardH Posted May 4, 2009 Share Posted May 4, 2009 (edited) OK, I picked up an [url="http://www.eminence.com/guitar_speaker_detail.asp?model=ACOUSTINATORNH2008&speaker_size=8&SUB_CAT_ID=6"]Eminence Acoustinator NH2008[/url] with the intention of using it to make a decent small cab as a practice amp - but with the hope that I may be able to use it for acoustic style gigs etc. [url="http://www.eminence.com/pdf/acoustinator-nh2008.pdf"]Spec sheet[/url] Looking at the [url="http://www.eminence.com/pdf/cab-acoustinator-nh2008.pdf"]cab design sheet[/url] it appears that I can get something that is fairly flat (at -3db) down to 60Hz or so, using a 0.8 cu ft box, but it will reach displacement limit at 55W. Smaller cabs will roll off sooner but have a higher wattage displacement limit. Originally I'd intended to simply ccale down the design for the Electrovoice 1x12" cab, but thought I ought to look into it a bit more. The vent recommendation is for a single 3" round jobbie 9.23" in length, but I was wondering how using a larger "slot" style vent as per the Electrovoice, fEarful and Barefaced cabs would affect things. From what I understand, a larger vent than is "correct" can offer some benefits, or am I going completely bonkers? Edited May 4, 2009 by RichardH Link to comment Share on other sites More sharing options...
alexclaber Posted May 4, 2009 Share Posted May 4, 2009 If I were you I'd go for the larger design as it gives a reasonably low F3 and is tuned low enough to not unload excessively with bass guitar. The higher tunings will indeed take more power above the tuning frequency but they'll also unload higher up so where you win on the one hand you lose on the other - fine for acoustic guitar where the lowest harmonic hitting the cab is likely to be 82Hz but with electric bass there will be some content down to 41 or even 31Hz unless you have a highpass filter in the signal chain. Larger vents work better because they suffer less friction, couple better with the air outside and cause less distortion - but as this 8" woofer doesn't move much air the recommended port only hits 5% Mach at 55W (which is where the woofer hits Xmax). Should be a very nice practice cab! Alex Link to comment Share on other sites More sharing options...
RichardH Posted May 4, 2009 Author Share Posted May 4, 2009 Cheers Alex. So the 3" round port will be OK then - bit long for the prospective size of the cab though - I'll have to play in WinISD. If I were to build a slot port, and guidance on dimensions? Don't go spending loads of time on it though... Link to comment Share on other sites More sharing options...
alexclaber Posted May 5, 2009 Share Posted May 5, 2009 You could put the 3" port on the side, that should fit. Alternatively use a shelf port 0.8"x8" (i.e same csa) and make it 6" long (2/3 calculated length due to shelf port having extra end effect). Alex Link to comment Share on other sites More sharing options...
RichardH Posted May 5, 2009 Author Share Posted May 5, 2009 Oooo ta Alex, I'll give that a bash with a slot port, methinks. Link to comment Share on other sites More sharing options...
RichardH Posted June 3, 2009 Author Share Posted June 3, 2009 Some progress.... or how to build a cab in 3 hours. [b]9:00am - OK, let's build a cab.[/b] I'd already determined that I was going to build it with a volume of 0.88(ish) cu ft (25 litres) and a tuning freqency of 52Hz from tinkering with WinISD. So I took some measurements from my LittleMark and exisitng 1x12 cab, as I wanted to make sure the LittleMark would sit on top of my lovely new cab. From these I produced a fully rendered 3D scale drawing of the final cabinet, allowing me to fully appreciate the final product... ...Or not. I chose the internal width to be the same as the LM and the height to be the width of my 1x12, which then gave me the depth as shown. I wanted to do a full width "slot" port like on the Electrovoice designs, and thought that 30mm would be a good height for it - WinISD gave me a vent length of 252mm. From advice from Mr Claber, I reduced the vent depth by 2/3 to allow for the boundary effect, which gave me the 165mm depth. Oooo, I'll add 20mm to the depth to allow me to recess the driver and maybe fit a grill or something, eh? [b]OK, it was 9:20am by now - time to get going![/b] I only had an offcut of some nasty WBP 12mm ply, but this was meant to be a test run, so that'll do. Measure... measure - OK, it's 610x1450mm. Bloody hell -I can get all the 280mm panels from one rip down the length of the panel, with about 20mm wastage ...and cripes - the remaining panels (310 width) can come out of the remainder with minimal wastage, leaving me with a neat rectangle left over that can be used for something else. It's almost like it was planned! Look! Some G clamps, an aluminium section as a straightedge and my trusy cordless circular saw, and we have some panels. Now I'm afraid it's all a bit of a blur here, as my and my chum got moving a bit quick, and I neglected to take any photos. Anyway, before you could say "time for a brew" it was 10:30am, we'd tidied up the tools and we had this (Actually the sealant was put on later - after the glue (PVA) had dried). Our respective other halves were returning from an early moring sortie to North Weald market, so it was time to get the coffee on and start making breakfast (bagels filled with bacon, fired mushrooms and a fried egg, if you're interested). [b]Get the little chappy finished, then[/b] Just a few minutes work to get the final side panel fixed into place, and some sealant applied from through the speaker hole. Pop out and do a bit of rubbing down and filling at odd 5 minute intervals through the day... Oh, and staple gun some wadding in there. It's like it was meant to be - I had just enough left to do this cab. Hmmm - maybe this will look OK after all - and it's screwed and glued, so even that thin veneer won't be too much of a problem... Let's whack some Tuffcoat on shall we? I reckon so far it's taken around 2 and a half hours. Watch this space! Link to comment Share on other sites More sharing options...
Musky Posted June 3, 2009 Share Posted June 3, 2009 Looking very good so far. Link to comment Share on other sites More sharing options...
RichardH Posted June 6, 2009 Author Share Posted June 6, 2009 (edited) Finished! With its dad Here it is with the G&L to give a better sense of scale Only bummer is that I'm getting some port chuffing centred around the bottom A. Odd, because for the size vent I chose, WinISD give a vent mach of 0.07 which is low enough. Maybe the cab volume was significantly lower than designed because I didn't bother to take account of speaker cone vol? Having said that, this was at fairly high volume... I may have to have another go - this time with better ply! Edited June 6, 2009 by RichardH Link to comment Share on other sites More sharing options...
alexclaber Posted June 6, 2009 Share Posted June 6, 2009 If that larger cab spawned the baby one then I'm starting to worry about a Terminator situation... "When bass cabs took over the Earth!" B-Movie? Alex Link to comment Share on other sites More sharing options...
RichardH Posted June 7, 2009 Author Share Posted June 7, 2009 LOL! Link to comment Share on other sites More sharing options...
Kongo Posted June 17, 2009 Share Posted June 17, 2009 [quote name='alexclaber' post='479083' date='May 4 2009, 04:22 PM']If I were you I'd go for the larger design as it gives a reasonably low F3 and is tuned low enough to not unload excessively with bass guitar. The higher tunings will indeed take more power above the tuning frequency but they'll also unload higher up so where you win on the one hand you lose on the other - fine for acoustic guitar where the lowest harmonic hitting the cab is likely to be 82Hz but with electric bass there will be some content down to 41 or even 31Hz unless you have a highpass filter in the signal chain. Larger vents work better because they suffer less friction, couple better with the air outside and cause less distortion - but as this 8" woofer doesn't move much air the recommended port only hits 5% Mach at 55W (which is where the woofer hits Xmax). Should be a very nice practice cab! Alex[/quote] OMG seriously...I must brush up on this information! I give my bandmates a headache as it is...Imagine if you were the bassist! How did you learn all of this? Link to comment Share on other sites More sharing options...
alexclaber Posted June 18, 2009 Share Posted June 18, 2009 [quote name='Kongo' post='516782' date='Jun 17 2009, 07:22 PM']How did you learn all of this?[/quote] Just picked it up over the years! I did do a mechanical engineering degree so I like to know how stuff works. But one of my first questions on The Bottom Line (email thing for bassists, before forums existed) was what can I do to get my 30W combo heard in a metal band... Alex Link to comment Share on other sites More sharing options...
escholl Posted June 18, 2009 Share Posted June 18, 2009 [quote name='alexclaber' post='517127' date='Jun 18 2009, 08:19 AM']But one of my first questions on The Bottom Line (email thing for bassists, before forums existed) was what can I do to get my 30W combo heard in a metal band...[/quote] did you try stuffing it with gunpowder? that would get you heard, briefly. Link to comment Share on other sites More sharing options...
Kongo Posted June 18, 2009 Share Posted June 18, 2009 [quote name='alexclaber' post='517127' date='Jun 18 2009, 08:19 AM']Just picked it up over the years! I did do a mechanical engineering degree so I like to know how stuff works. But one of my first questions on The Bottom Line (email thing for bassists, before forums existed) was what can I do to get my 30W combo heard in a metal band... Alex[/quote] Proof we all do start somewhere...so there is hope after all haha! I'd just like to know more about the tech sides to amps so I can judge one pre-played by looking at more than just watts and ohms and speaker size / number of speakers etc etc. Link to comment Share on other sites More sharing options...
escholl Posted June 18, 2009 Share Posted June 18, 2009 [quote name='Kongo' post='517601' date='Jun 18 2009, 05:19 PM'] Proof we all do start somewhere...so there is hope after all haha! I'd just like to know more about the tech sides to amps so I can judge one pre-played by looking at more than just watts and ohms and speaker size / number of speakers etc etc.[/quote] as someone who does know all the tech stuff, i can tell you still that the only way to judge and amp really, is to play it at volume. most manufacturer's specs are dubious and/or meaningless at best -- and even if they weren't, amps and speakers are such complex things that it would be nearly impossible to qualitatively evaluate them, nevermind analyze all that data. Link to comment Share on other sites More sharing options...
alexclaber Posted June 18, 2009 Share Posted June 18, 2009 [quote name='escholl' post='517784' date='Jun 18 2009, 08:17 PM']as someone who does know all the tech stuff, i can tell you still that the only way to judge and amp really, is to play it at volume. most manufacturer's specs are dubious and/or meaningless at best -- and even if they weren't, amps and speakers are such complex things that it would be nearly impossible to qualitatively evaluate them, nevermind analyze all that data.[/quote] I agree. The most important thing is to actually ignore all the silly specs which abound, they're not only a distraction they're misinformation. Even some weight specs are way out (of date, Epifani!) Alex Link to comment Share on other sites More sharing options...
Kongo Posted June 18, 2009 Share Posted June 18, 2009 [quote name='escholl' post='517784' date='Jun 18 2009, 08:17 PM']as someone who does know all the tech stuff, i can tell you still that the only way to judge and amp really, is to play it at volume. most manufacturer's specs are dubious and/or meaningless at best -- and even if they weren't, amps and speakers are such complex things that it would be nearly impossible to qualitatively evaluate them, nevermind analyze all that data.[/quote] [quote name='alexclaber' post='517974' date='Jun 18 2009, 11:11 PM']I agree. The most important thing is to actually ignore all the silly specs which abound, they're not only a distraction they're misinformation. Even some weight specs are way out (of date, Epifani!) Alex[/quote] I cannot agree with both of you enough! The only problemo is you really want the band there and at actually volume too. I've tested amps, thought they were loud...too em in with the band...sub par at best! Then it breaks up when you crank it more, making more noise than volume. But this stuff you guys know is very usable. Sure, it may give some people a headache but if you were to speak to a soundguy or music techie it's like going to Japan knowing Japanese, far easier to communicate and your more likely to be taken seriously. Link to comment Share on other sites More sharing options...
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