Chienmortbb

[quote name='Bill Fitzmaurice' timestamp='1406985707' post='2516449'] They don't. An undersized port can cost you 3dB. By using a flare you can recoup some, if not all, of that loss, but it won't give you 3dB more than a port that's correctly sized to begin with. [/quote]I was paraphrasing the blurb on the Precision Ports site Bill and my worry always was that, as in plumbing, the flow is dictated by the smallest bore in the system. Whilst turbulance may be reduced, the air velocity and c the pressure is still high. So is this treating the sympton rather than the disease?

Ports. Flared ports supposedly give you an extra 3dB so this should mean you could work with an air velocity of 30+ and not suffer the turbulence we hear as chuffing. However there is only so far you can take this as you cannot fight physics. Precision ports would put about £30 on the project price and that seems to to defeat the low cost of the driver. Duke Le Jeune recommends a diagonal 45 degree cut on the inner end of a straight port to give a larger area at the port entrance. This adds one port radius (ie 37.5 mm for a 75mm diameter port) to the length of the por but as the air move both ways, this may not be as effective as the correct sized port. At least with a slot port you only have one large round hole to cut.

I have just reread the thread about 3 times and apart from realising what a pompous ass I sound, it has been very informative. Firstly the Beyma SM212 driver. I don't know how I missed this driver when searching before but it is a gem, it models really well and I am struggling not to order one now. I will wait until the end of the project though. Secondly, the choice of 12mm Ply for the cab. This clearly means more work for the three musketeers, but will end up with us all learning more. As the concept is that you can get your wood cut at B & Q, can you confirm what plywood you are using? The standard stuff at B&Q is a fairly medium grade Exterior Ply although they do do Birch and Spruce in 19mm thicknesses only. My first PA speakers were built by my Dad from 12 MM exterior play and properly braced they are great. Also what wood adhesive? On the prototype cabs there are a lot of screws around the baffle. The fearful build are screwless, relying on the strength of the adhesive. Why so many screws? Will the design be screwless or is that not part of the design criteria? Hmm just rethoughtthis and realised that you have to have full acces to the interior to play about with bracing.

I have to agree that 3012 might improve matters but I feel the whole cabinet could be compromised. They look good and you like the sound so stay with that for now. Without a lot of work you will not get the results you required and could spoil the cabinets.

[quote name='mcnach' timestamp='1403294807' post='2481664'] it's definitely a bit of both, when it comes to onstage volume. I have used two cabs onstage live many times now, not so much because I need the volume (I'm DI'd most times, and onstage two cabs is unnecessary), but because the stack is higher and I can hear it better using probably less volume overall. It seems a bit wasteful, but the cabs take up so little space and are so portable, so why not? [/quote]Perhaps Barefaced should add dummy cabs to the range as cabinet stands. I am not sure wheterI am joking or not!

[quote name='charic' timestamp='1406621298' post='2512987'] Chien, if you're trying to post up the results using HTML you're onto a losing battle against the software I'm afraid Tables don't work in these 'ere parts [/quote] Ha Ha I have just found that out. I will convert to a jpg and post them later.

I bought a Hornet Bass 45 for a practice amp. Would pulverise many 100 watt combos I have played.

[quote name='Bill Fitzmaurice' timestamp='1389204252' post='2331349'] It can make the crossover appear as a dead short. Read this: [url="http://www.bcae1.com/xoorder.htm"]http://www.bcae1.com/xoorder.htm[/url] An Lpad will only work as it should with a resistive load, piezos are a capacitive load. To use a piezo with either an LPad or a crossover additional components are required. [/quote] There is much myth and mystery about Piezos and you have to blame Motorola for poor marketing. Piezo tweeters work better and are protected by the series resitor but it does nothing to succesfully integrate a piezo tweeter into a speaker system. For proper balance between the tweeter and the other drivers, it has to have a proper crossover. Then you get a smooth response that will outperform compression drivers. One thing to be aware of though is that if MB only use the dreaded series resistor, then just replacing the piezo with a traditional magnetic tweeter will result in speaker failure eventually and not give a very good performance untill then. Do you have picture of the tweeter? What make and model is it?

[quote name='martthebass' timestamp='1406129814' post='2508630'] Funny you mention that I've had a Behringer mic for years and it outclasses the SM58 for clarity........still use mine in preference to one. [/quote]I read that many BBC soundmen carry Behringer mics as they sound better than SoMe others.

OK I have modelled the two Kappalites and there is no doubt that the box you are using is far from ideal for the Kappalite 3015LF. Your box is less that 50 litres internally and that is ideal for the 12" but the 15" prefers a much bigger box. As is you probably have a small peak at about 100 -120Hz an a steady roll off from sbout 90. In the same cabinet, and with the right porting the same cabinet cold give an extra 6dB around the 40-60Hz area, the area that the Acme's are strong. Ironically the current thread would probably give you better results than the cab/speaker combination you have. On the plus side, the cabinet you have is small, neat and if it works for you, keep it. I don't think you could install a 12 in this cab without major surgery and I am not sure where you would put the ports. Are there any ports on the back?

[quote name='redstriper' timestamp='1406217414' post='2509442'] Thanks but I won't do WinISD because I don't understand graphs and I have no time to learn. The internal dimensions are very small, since it is basically the tiniest cab you could possibly squeeze a 15" driver into. I just wanted a rough idea of what the difference would be if I changed the 3015LF for a 3012LF. Stevie suggested I should expect more low end and I wondered if there were any other considerations and whether it would be worth the effort and expense. The Flite cabs are made of a composite material, I'm not sure of the details but I think it's foam sandwiched between thin ply. They are very light, under 10kg loaded with the 3015LF and having got used to such lightweight, I am loathe to change them. They also sound better than any other 15" cab that I've tried, which is quite a few, but I've been advised that they are too small to get the best from the 3015LF. [/quote]Give us the inside measurements of the cab and I will model it for you.

[quote name='tauzero' timestamp='1406199467' post='2509215'] I suspect it's whatever material is left after Peavey and Trace Elliot have sucked all the heaviness out of it to include in their cabs. Which reminds me, what sort of quality was the 12mm ply used in the prototype cab builds? B&Q quality or top quality Baltic ply with voids filled with unicorn tears? [/quote]B&Q only do baltic birch in 19mm. That is quite heavy ( think MDF on a diet). I don't know but I suspect that it is bog standard 12mm exterior ply. The Baltic Birch 19 mm is about £75 for a 2440 x 1220 (8x4) sheet. The exterior ply about 1/3 that.

[quote name='LukeFRC' timestamp='1391642863' post='2359790'] interesting thread from the PA side. Looks a nice driver - I found a pre-fearful greenboy and bill fitzmaurice talking about that 12n630 over on talkbass, but they don't seem to have thomann in the us! [/quote] The 12n630 seems to have a really nasty peak (12dB approx at 2KHz) and to me that means it is only useful in a 2 way or 3 way system.

[quote name='LukeFRC' timestamp='1406118614' post='2508471'] well you just named it - 3 musketeers 112 [/quote] 3M112 it is then?

To the three musketeers, My comments were not meant as a criticism just advice. I hope I did not upset anyone. I have found it a good idea to keep an open mind when it comes to design and i am learning a lot from what you guys are doing. Much of what I have learnt is from guys like Bill, Alex and Duke, and much of that seemed counterintuitive at the time. Bill on particular continues to push the boundaries on enclosure design. Keep up the good work.

[quote name='LawrenceH' timestamp='1406036918' post='2507721'] I still think the limits imposed by the shape of the LF transfer function on the bass end are being ignored, or at least not given much priority. The only practical way of making eg a Vanderkley sound like an Acme in the bass would be with DSP filtering, regardless of xmax/power limitations, because the EQ on even quite a flexible amp won't be able to sufficiently compensate for the difference in cabs to give a similar overall roll-off curve. This is another reason to think carefully about tuning in the 40Hz versus the 50Hz regions, since tuning lower can give a curve that is easier to EQ within the range you actually care about using the EQ controls found on a typical amp (eg 12dB/oct shelving filters for the bass). [/quote] The tuning frequency of a cabinet should be chosen to suit the driver. Most mid-bass drivers do not behave well when tuned too low. It can compromise the max power before XMAx is exceeded and so increase fartout. It also increases the very low frequency travel of the cone, increasing the boominess. Most shelving type bass comtrols make this worse. If you need the extreme low end response ( and there are very good reason why you don't) you probanly should look at say the Eminenve Kappalite 3012LF, Precision Devices PD12SB40 or some of the Beyma & Faital Pro dedicated bass frequency drivers.

[quote name='funkle' timestamp='1404387797' post='2492148'] Beyma SM212 specs - [url="http://www.beyma.com/uploads/ftp/Fichas_Tecnicas/000000730.PDF"]http://www.beyma.com...s/000000730.PDF[/url] Interesting reading. The 98dB @ 1w/1m is an impressive figure. Not too heavy for a ferrite speaker. An apparently economical solution for a 2 or 3 way full range box. Vd of 382 cc and Xmax as you say 7mm. I wonder if the Xmax of 7mm calculated in the same way that Eminence do their Xmax calculation? The 3012LF, a high standard of comparison for Xmax in current bass cab drivers (apart from Alex Claber's proprietary 12" driver, where Vd is high - apparently 550cc - but we don't know how it is calculated) has bigger Xmax (9.1mm) and Vd (496cc) but much less efficiency at 1w/1m. I assume the 3012LF would really get going at higher power levels, and I note is rated for 450W RMS. Eminence specs - [url="http://www.eminence.com/pdf/Kappalite_3012LF.pdf"]http://www.eminence....lite_3012LF.pdf[/url] I assume the Beyma SM212 is significantly cheaper than the 3012LF, and would lead to a simpler build? The Greenboy and Audiokinesis builds around the 3012LF are not cheap, I assume due to the extra parts, labour, crossovers, and additional drivers used to cover mid and higher ranges... [/quote]In the UK the SM212 is lower than half the price of the 3012LF. In fact you could buy two and still buy us all a good drink.

[quote name='Badass' timestamp='1349425309' post='1826059'] [b]Chienmortbb[/b] that second link is 404, and chance of a re post of it? [/quote] Sorry, I don't know what happened but it seems fixed now.

You can get 180W if you run them wrong. Running at 800V, will lead to valves wearing out much faster and the life of a guitar or bass amp is far tougher than a hi-fi amp or indeed a PA amp in those days. Valves are traditionally thought of as electrically indestructible but like transistors, if run close to their absolute maximum ratings, will fail sooner. If you want to find out how good and how bad both valve and solid state amps can be, without the BS go to both of these web sites. Their is some very good reading [url="http://lenardaudio.com/education/14_valve_amps.html"]http://lenardaudio.c...valve_amps.html[/url] and http://sound.westhost.com/valves/index.html The authors of both sites design and build Valve, SS and MOSFET amps and do know what they are talking about.

They are missing something. You cannot get more than 30 watts per EL34. That I'd why Marshall sound city etc rated their heads with 4 EL34s at 100 watts.

[quote name='DHA' timestamp='1190997164' post='67034'] I still don't understand how they get 300W from only 6 EL34s, I think they mean peak and not rms. So I would say its more likely to be 150-160W rms. Or am I missing something [/quote]

My first Amp was a VOX AC30 Bass and I loved that amp until I changed the valves and then it sucked. I was an electronics apprentice at EMI and I later learned why. If you change the valves you have to set the bias to suit that particular valve. I later bought a Sound City 100 Watt head and cabinets (I think they were 4 x 12s but time dims the memory). Great amp that came to an abrupt end. A pint of beer was rested on my amp by the singer. With the vibrations it slowly crept across the amp finally depositing about 3/4 pint of directors bitter directly (pun intended) onto the four EL34s. Cold beer plus very hot valves = glass and beer everywhere. II ended up playing the rest of the gig with a 50W SS Pa Amp. So the moral of this story is that valve amps are mechanically fragile and need a great deal of love. In return they may sound great, they may sound bad but they will sound different to a transistor amp (don't get me going on ICs). I have to say that to date may favourite amp was my Trace BLX combo. Weird looking thing but sounded great. With an extension cab would outperform many 200 watt heads. Trace used MOSFETs as the output devices. ironically Peavey bought the Trace name and when I last heard were making them in the UK still. In my opinion, unlike a six string egg slicer (guitar) a bass should sound like a bass and the distortion so loved by guitarists is not what I want for a bass. Many of that great bands of the pasts used bass rigs that probably never got close to 100Hz at the bottom. The bass sounded like a bass because the harmonics way up the frequency scale do not decay much so most of the "bass" energy of say an open E is above 100Hz. It makes more sense to go as low as you can on a 5 string but striving for 25Hz may not be the Nirvana that many seek. Oh I now use an HH Bassman100 bi-amped into an HH VS Bassamp feeding a Ramsa 12" Sub and Ramsa 12" full range PA speaker. To me it sounds divine but maybe the cool lighting of the VS Bassamp sways it for me. I suppose that is also why some people love an SVT rig. It does look cool in the same way as a 100W Marshall stack does. Fender Aerodyne Jazz bass completes the rig. I will now sit back and prepare to be flamed

[quote name='ogri' timestamp='1346104801' post='1785449'] man is this thread still running lol!! im a convert from the last time i posted onnit. i always loved valve amps, bought a yank svt classic years back, discounted down from £1650 to £1050. cost me another 200 sovs to flightcase it.ran it with a Ev loaded mesa boogie 4x10. loved it, and it delivered til it got a few years old, when it started getting unreliable, despite being regularly serviced. was bloody heavy in its pukka case, and cost a lot everytime it needed valves. then it got even more unreliable. had it serviced, advertised it here, some young feller came down with the dosh. it bloody blew up while he was trying it...had it fixed(another 100 quid) he bought it, took it away. a week later got a call from his amp tech(checked out genuine) summat else had gone wrong. gesture of goodwill i paid that bill too. bye bye ampeg and bloody good riddance. anyhoo, two years down the line this time around i gotta get me gear sorted from scratch, right bloody quick like, and to a tight budget. i buy all secondhand..a GK rb 700 combo off a feller on here for £380, a eighties MIJ precision off another bloke in peterborough for £350 and a sansamp valve amp emulator thingy(what a cracking bit of kit) off a mate for 100 sovs. leads etc takes my spending to about 900 quid, and im sorted. so i get to the gig, and gorblimey guvnor!! it all sounds better than my old rig!or at least as good...and everything all together cost less than me old svt alone! i know valve amps are the mutts, but im done with the expense and unreliability issues, i'll stick with what ive got and be well happy with it, without feeling like a poor cousin to anybody with a tube amp. but then again thats all just my humble opinion, and whatthe hell do i know, im only a brickie.. [/quote] Probably a Brickie that knows more about Bass kit than me and a lot of others,

[quote name='4 Strings' timestamp='1349194930' post='1823118'] heh, pretty sure my Hartke gear wasn't built in the US either, but you know what I mean. [/quote] The drivers for some of the Ashdowns are made in Italy and the Electronics in China, all to UK designs. Their more expensive stuff is still made in the UK. With regards to Hartke, it always sounds to me like Bass Gear designed by a guitarist. With regards to the Cab design, I don't believe that most Bass cabs are designed to HiFi standards and if you take some of the best bass cabinets and put the figures through WinISD or another Cabinet Emulator, you will find that the response is far from flat. So leave the speaker in the Ashdown Cab as long as it sound good to you.