Chienmortbb

Bill is right of course but I suspect there are many worse that that Ashdown plot out there. The other useful figure would be the off axis response,

Re-reading Phil's comments, I have to agree that there is a potential problem with plain butt joints on plywood. The adhesive works best on the face of the board and less well on the cut edges. Hence battening each edge solves that problem. The (partial) solution to this is to seal the cut edge with a 50/50 solution of water and PVA woodworking adhesive prior to making the butt joint. Of course we have not published the design as yet but the bracing is comprehensive and that can only add to the strength. The offline "discussion" as to how to construct the cabinet was "frank" and of course, Phil is right that the strength of a fully edge attend cab will be stronger that one without the edge bracing.

i don't want to steal Stevie's thunder but I will try you explain the thought processes after three beers. Firstly, 15mm Poplar ply. The stock we can get is 9 ply and that is for either 15 or 18mm. To try to keep the weight down we have gone for 15mm. So 6mm dowels can be used with care. I have not tried pocket holes on 15mm stock so I cannot comment although I have a pocket hole jig and use it or other projects. In theory there is no problem in porting at the back but again I will bow to Stevie's superior knowledge. I know Stevie was planning on looking at alternative drivers/voicings to satisfy the Old School brigade but I don't think the Kappalites were what he was planning to use. The Kappalite 3012LF is a great LF driver but there is some debate as to whether it is ideal in a bass cabinet. I am going out on a limb here but the SM212 performs better overall than any of the Eminence drivers I have heard over the LF and mid range. Its problem, like all 12" speakers, is beaming. It is the beaming that we are trying to design out. To explain beaming, think of lighting. The two extremes are spot lights and flood lights. A spot sends out a narrow beam of light picking out a single performer. Great for Sinatra or Robbie Williams but... where's the band? Beaming is a spotlight and we want a floodlight. The problem, with beaming for the working bassist is that unless you have ears in your knees, you need either a separate monitor, a second cab atop the first, IEMs, or a cab designed for wide dispersion to hear yourself on stage. Having heard one of the Eminence drivers in the prototype MK2 and MK1 cab, the only thing the Kappalites will give you, i[b][i]n my opinion[/i][/b], is light weight and an empty wallet. The 3012LF has a peak in the response at about 2Khz. For the P-Audio tweeter the crossover frequency needs to be higher than that. The peak on the 3012HO is much higher but is not the LF beast that the 3012LF is. It has an Xmax of only(sic) 6.2mm compared to 8.25mm for the Beyma SM212 and 9.1mm for the Kappalite 3012LF. So the HO cannot move as much air. Of course the Kappalites are 2Kgs or 5lbs lighter and that may be a reason for using them. [size=4]Both Eminence drivers have higher power ratings but the difference is small enough to ignore. The SM212 is rated at 350W, the 3012HO at 400 [/size]and the[size=4] LF at 450. The difference between 350W to 450W is under 1dB[/size] in an ideal world and 1dB is audio's JND (just noticeable difference) in ideal (quiet) conditions. Standing next to Animal you won't hear it. Of course the Kappalites have bigger voice coils (3" rather than the 2.5" for the SM212) so may handle more power that the raw specs would suggest. If you want a flat response, HiFi voicing, then the SM212 is ideal. If you want Old School then other drivers need to be considered, Stevie has both the MK1 and MK2 prototype cabinets and they will stay with him so he can check different drivers. One last thing, don't rear port until ,Stevie has confirmed or trashed my views.

When I contacted Stevie about this originally I was aiming for a single driver with a weight coming in at about 14KG. However once I heard one of Stevie's cabs I was hooked on a two way. From my rough, calcs, the tweetered version should come in something under 16Kg and the compression horn version that I am building 17Kg. A good HF unit is weighty and although the P-Audio Tweeter and the Celestiion compression driver are about the same weight, the crossover for the compression horn weighs and costs more as it crosses over much lower than the Tweeter. As I understand it Stevie will publish the twittered design initially. [size=4]Stevie will be able to give you more info though. [/size] As for the size, the final size is to be confirmed (non) but the prototype was taller than the MK1 (60mm wish )and the other two dimensions were smaller. About 10mm smaller on the width, and 40mm ish on the depth. Sorry to be vague but I built the prototype from 18mm ply and the final design will call for 15mm. Regarding the build, I will let Phil answer the dowel question but I will be using them.

Agreed if there is nothing wrong its fine. Just enjoy it.

What Norris said plus if you have put a new bridge on the action(string height) will need to be adjusted. There are two real p[possibilities, High fret or if not a high fret, you may have the dreaded ski jump where there is a bend upwards at the body end of the neck.

Its a 250Watt amp. I think that is what the OP was getting at. There was no such thing as Dynamic Output watts.

Of course the maximum voltage swing is a limiting factor in the power output by an amplifier but is not the only one. Many amplifiers have power supplies that cannot supply the extra current needed by 4R speakers. As an example, the Hartke 3500 Is rated at 250 watts into 8R and 350 watts in to 4R. The power supply cannot supply enough current. Power is the product of Volts x Amps so Voltage is important but cannot be considered in isolation. As for the actual SPL, if using the same driver in the same enclosure, not driven too hard there will be a correlation between a change in the power output by the amp and and change in the acoustic output from the speaker system. It may not be linear but over a limited range it will be affixed relationship. Of course if you drive the speaker too hard, power compression becomes a factor and the relationship is broken.

Assuming both cabs are 8 ohms, that will be fine. If the Head had two output sockets it is better practice to take a cable from the head directly to each cabinet. Otherwise all the power goes into the top cable,

Wow this is unmissable. Will a day be enough time?

As Stevie says I am going to build the cab with a Celestion Compression Driver coupled with a P-Audio horn. The horn has unusually wide dispersion and should be useful for allowing me to hear myself even when just in front of the cabinet. We really need some commmercial cabs for comparison purposes. I have a TC BC212, it is a mid range cab but it would be really helpful to have more cabs that we can test in controlled conditions. Can you help? The knowledge we are gaining and putting on here is useful even if you don't want to build a cabinet. Some of the findings have surprised me and with open minds, free of commercial pressures, we have no axes to grind. The port situation is a good example. One big horn (ooh err Mrs) is a lot better than a few small ones. It is likely that multiple slot ports are also an issue for exactly the same reason, who knows what else we will find with enough cabs to check. Anyway thanks for reading and if you could help in any way....let Stevie know.

Do you have a picture of the plastic part. I have used the ,K&M version before but now have financial constraints. Ido have a good workshop though and could probably kno I ups metal part to replace the plastic part.

Do you have a picture of the plastic part. I have used the ,K&M version before but now have financial constraints. Ido have a good workshop though and could probably kno I ups metal part to replace the plastic one. Douroucoulis have a picture ofit?

[quote name='BassBunny' timestamp='1487842250' post='3243365'] As it's a Class D amp, the options are limited as to self repair. I would get in touch with Marshall, (who now own Eden), and arrange to send it to them. all my dealings with them have been excellent. If it is still under warranty, then they will sort for free. Oh and what Jack said although Eden still have that killer tone for me. [/quote]Yes my dealings with Marshall have been second to none.

[quote name='stingrayPete1977' timestamp='1487696767' post='3241945'] At our last gig we made a car crash of the stuff we practiced at the previous rehearsal yet I was apprehensive about the songs played on double bass as I hadn't practiced at all, they were our best songs all night! [/quote]last rehearsal syndrome. If it goes well the gig sucks if rehearsal sucks the gig usually goes well.

[quote name='BigRedX' timestamp='1487243103' post='3238278'] The fuse in a detachable mains lead is there to protect the lead, not the equipment it is attached to which will have its own appropriately rated fuse. The difference between a lead for a kettle and a "kettle lead" has already been adequately explained in previous posts. Surge protectors/power conditioners and similar are only really required in places like the USA who have a considerably less than robust electricity supply compared with the UK. IME when there have been mains problems in this country nothing less than a properly spec'd UPS would have been suitable. [/quote]Correct this is why "power conditioners" are big in the USA and not here. Much old waiting in the US was done with aluminium not copper and that is more problematic, much noisier. Surge Protectors and power conditioners are sna[size=4]ke oil over here. [/size]

if you are using "dead " flats many treble controls will not add much.

[quote name='T-Bay' timestamp='1487691691' post='3241878'] Having designed and built electric race cars the dealings I have had with electronics engineers over the years have had me pulling my hair out. I have only met one reliable one in all the years and he is now one of my best mates. He is the first to say what an unreliable bunch they are as a whole. Good ones are in such demand they can get away with being unreliable and troublesome in ways other trades can't. Bad ones still get by as often they are the only ones you can get to look at stuff as the good ones are so busy! [/quote]Are you talking about Engineers, Technicians or just repairers?

Jack every cabinet from Behringer to Bergantino and Barefaced are compromises. There is no such thing as a mathematically perfect cabinet but some are better than others and some suit some people more than others.

When they 1x12 Design Diary was started by Phil Starr and Stevie, the aim was to produce a 12" cabinet that would keep up with a loud drummer (i.e. 120dB). The cabinet that was designed di that and at about 250 watts if memory serves correctly. two cabinets should really be able to beat that is they are efficient.

[quote name='markstuk' timestamp='1487419250' post='3239643'] But do they have hefty thumpiness? [/quote]You are a very naughty boy!

The problem is with Class D, too many people hyped what it could dom and with names like Cool Amp and ICEPower. The legend lives on. ICE by the way is for Cool not In Car Entertainment as some continue to call it. Although Class D runs MUCH cooler than class A/B, It does generate some heat . As a rule of thumb about 17% of the rated output is heat so for example a 100W amp will produce 17 watts of heat based on a true output figure and an average efficiency in both power amp and power supply of 90%. A 500 watt amp will produce almost 100W of heat, the same as an incandescent 100W light bulb. Put that amount of heat into a small container and you could have trouble. Now here is the rub, the amount of heat generated is only partly the result of increased power output. There is a quiescent heat generated even at zero watts out. That quiescent heat depends on the design but is usually about 10-15% of output power so 50-75 watts at no output. So to keep heat under control, you need heatsinking and/or a fan or two. Nowhere near as much as a class A/B amp but it is needed. In a 1U chassis there is restricted airflow so heatsinking does not work so well and 40mm fans do not shift a lot of air. Also fans are a lot less reliable than heatsinks, although a lot lighter. Then you have to fit the preamp and connectors in. [size=4]Going to 2U makes life simple and solves most of the problems and that is [/size]what[size=4] a lot of amps are [/size]about[size=4] 2U (88mm or about 3.5") high even if they are not 420mm(19") wide.[/size]

Just one question, Jacks or Speakon? If your amp has jack outputs that could be the culprit. I remember one amp manufacturer putting a very high percentage of power amp failures down to shorted jack cables.

Go for it. Many commercial cabs break many of the rules and are revered. I am sure your cab will be more than useable and what have you lost. You can also come on here and say I told you so Your expectations are low and you might have a very pleasant surprise. So build it and tell us what YOU think.

Yes the voltages were unified way back in the 80s I think. Thank you EU [size=4] [/size]