Mid-High Wattage

[Phil]

Hi, I am using 1.2k rms subs per side so what would you say I would need for the mid high. I am guessing around 400 w rms per side?

My mid speaker will be about 400 watt rms so would you say a 100 watt compression driver. - am am making these cabs.

Phil

know anywhere where i can get either cheap cab paint or carpet?

[soundmanjim]

dunno about carpet - blackboard paint would go well on your finished cab. still think u would be better off buying a couple of cabs - i bet once you have added on the price of all the materials you could have bought a couple of sx300 ev's!

300-400w is more than enough - if you want it louder, more cabs and more amps; no point trying to make one cab do all the work.

[Phil]

The subs cost me £40 in wood for 4 and £280 in drivers, I know they are cheap but I'll give the Eminence Kappa LFs a go. They are put in a slightly bigger cab than reccomended - only just by a few litres. But I will see how they do. coming from thomann hopefully tomorrow.

What you think, slightly darker than turbo blue? or black?

All bands want my age is just a rock experience, none of them could tell what they sound like apart from me. They just want it loud and vibraty in ya chest lol.

I dont class these as a loss as it is nowt really - thats looking at the price of decent speakers. I just need a system of my own that can handle most places and get me abit of money. only 15, cant afford £1000s like i get with teh other bands rigs i run.

[shepz]

Seriously buddy... just save up and go for a decent option.
It might seem tedious and like it's going to take forever but if you have the right will power you can have numurous "regular" jobs going getting you towards your goal quicker than you may think!
Trust me from experience... skimping only costs you more in the long run amongst other pressures and stressed from "why the f**k did i do that for? if only i had waited another few weeks etc.".
While you're not old enough yourself to apply for a loan you may be able to get your parents to take one out on your behalf...

Take some time, write up a proper business plan with cash flow (make it realistic)... look around at what loans you can get and how much you need to be paying them back monthly.

Good luck!

[Phil]

The subs I have just built sound alot better than the peavy black widows. Hisys 15"s. I compared them side by side with same amps and settings etc. Nicer sound and more punch.

[gingerbiscuit69]

you should know by now its not about wattage ... its spl they produce!

i have some small 100w rms 6.5"+1" midtops, horn mid sections, roughly 106db/w efficiency, driven with 100w they are much louder than many 12"+1" combos driven with 500w!!

what subs u built, what are they loaded with? know their efficiency?


Sensitivity + Power Handling - Power Compression = Max Output

a 97db/w efficiency driver will need twice as much wattage to sound the same as a 100db/w efficient speaker.

every 'double loudness of a speaker to the ear' is a 3db gain, which generally takes double the wattage to achieve compared to before ect...

thats why horns are popular, as you can take the efficiency of a driver - say 98db/w, and by horn loading it, you can make it more efficient to say 104db/w, effectively sounding 4times louder compared to the driver in a simple reflex box. of course they are heavier and larger, but the result is great!

the whole thing about horns throwing further is a bit of a porky... only difference is they are louder and more directional (specially midtops), so by directing your 130db of sound in a narrow 35v x 35d degree space, you have more volume going where its needed so seems to 'throw further'.

for instance, reflex 100w rms mid driver 99db/w, reflex (front loaded) would only make about 110db, spread over a large area, much going to the heavens and walls... now the same driver in a horn could do 130db+ to a set area, same driver and same wattage going in.


so yeah ... thats my little rant about sensitivity. You must find out your speaker efficiency, input wattage and there ya go!

got scientific calculator?

*EFFICIENCY*dB + 10 LOG(*WATTAGE*) = *THEORETICAL OUTPUT* dB

note - efficiency must take into account the cabinet gain too, must model in a program like hornresp to find out this if you do not know.

note2 - hotter components get, higher friction in the circuits, will give u power compression, so at rated power shouldnt be too bad, but in my case, 700w rms driver, getting 1200w, i can expect to loose about 2-3db efficiency through compression.

[Phil]

Eminence Kappa LF - I know the name sound cheesy but they seem to do me fine. Thing I made a good cab design. I followed the reccomended capacity of the cab but added abit more. I think its between 110litres to 120.

I know what you all say about saving up for a decent system but Its tough coz I need to have a pa to start doing gigs and i need gigs to get the money for the pa. and what I charge its more or less nothing compared to the money you will get.

The speakers are 121db max thats between 50hz - 500 hz and its still over 100db for the whole of the usable freq range - 30hz- 2.7k

My plan is basically to get this system running make more money and save it untill I have the money to get a nice system. To me a decent full system will be over 5 grand!

Using JBL TR125 for mid high at the moment and I think I will Bi amp.

[Phil]

99 efficiency - take it it is average?

[gingerbiscuit69]

for reflex 98-100db/w is the average of half decent gear.

u can always cross the subs higher or lower to make up for the weakest link in the chain ... ie: if the subs peak b4 midtops, then lower the xover so the midtops take more of the ubber bass out.

many will agree subs should never play the vocals, most pro's will cross subs 125hz highest!

[Phil]

I forget what one of the rigs I work with crosses over but I think I set it at around 80 - 100hz - but I cant really remember. Had it all checked out by a engineer and he says I aint done anything wrong and its all good.

[muppet]

Most pro speakers on a 3 /2 system are crossed over at 60-90hz. The lower the cross over is set the tighter you bottom end will sound, the higher you sub is crossed over the more mushy it will sound. it is always good to also bear in mind that anything above 90hz is technically not sub bass. So rather than moving your crossover point to compensate for the components lack of bottom end I would suggest simply using a driver that can go down to 80hz which would allow you to set a crossover overlap, 80hz would be considered normal a pro top box. if you are lacking bottom end in your system rather than moving your crossover points try boosting around 40hz, this should increase the amount of movement the driver is making at thus drawing a bit more power and making it drive that little bit harder.

But If i can make a suggestion that rather than make your own boxes you actually buy them. For the same money you are taking about you can buy a full set of NJD cabs which are very cheap chinese imports but they are loaded with fairly high quality celestion drivers. Follow the links below I think Electrovision sells this stuff sells at around £150-£200 a box. The electrics are a bit cheap but for that money the box does sound very surprisingly nice.


www.electrovision.co.uk/product.aspx?prod=NJ560
www.electrovision.co.uk/product.aspx?prod=NJ562

[gingerbiscuit69]

...or save money and buy something decent...

that NJD stuff is just wrong...

for instance, that crossover at 3k means the poor 12" low driver has to play wayyyy too high! a reflex 12" shouldnt be taken over 2k highest, without adding a phase plug. the phasing and directionality goes all over the place, and the output seriously drops. if you measured this cab, id expect to see a huge dip in frequency response in the 2.5khz region! also means the comp driver is either really cheap as it cant be crossed lower or will have so much headroom the topend will be stupidly loud and harsh!

sensitivity of 96db/w, now driven with 300w you will get a theoretical output of 121db @ 1m.

take your tr125's - 99db/w, drive them with 300w and you get 124db @ 1m. thats effectively twice as loud as the others!

my JBL JRX 112M monitors (also used for small FOH), are 99db/w efficient, small light and versitile, 350w rms, but driven with 550w rms and love it! so 124db standard, or 126db at my power. for a small cab that isnt bad!

[gingerbiscuit69]

www.stageaccompany.com/en/support/splcalc.php

[John Bell]

Hi Phil, with reference to your Eminence Kappa loaded cabs, I have 2x SmartSound LP8SP and 2x LP8SP-PRO subs loaded with the 650Wrms Eminence Sigma-Pro 18" drivers, driven by a PSS2400 2.4Kw rms amp and they punch really well in my 4Kw rig. I can get more kick drum than I need in the venues I use.

My 2x SP5SP subs are loaded with the earlier, 400Wrms 15" Kappa's. They are fine for my compact 1.3kW rig.
John.

[muppet]

yep, as i say very cheap Chinese imports. the celstion drivers are actually quite decent but the electronics ie. the crossover network is very cheap but they do sound alright for the very cheap asking price. i do think that you would be surprised at how many cabs crossover at around 3k though. What matters is what the drivers are optimally capable of producing and providing they are matched correctly there is nothing wrong with a 3k crossover, for all we know that driver might be quite efficient at producing 2.5k. i have never heard these in multiple stacks so i can’t really comment on how badly they may phase but its worth remembering that all speakers have phase issues. To be honest at the end of the day these arnt cabs that i would buy myself but i was suggesting alternatives that are in the same price range and will have some kind of warranty included and they certainly sound far better than any peavey or equivalent products in this price range.