most bang-for-the-buck sub-amp

[skogs]

Hi! i just bought two TCsounds TC2+, and i need a high power amp for it. it has 2*4ohm coils, so i was thinking an amp with either 2*500w@8ohm (coils in series, drivers seperate) or 1*1000w@4ohm (coils in series, drivers in parallell)
So, how do you think i would get away using the least money? I Have considered the cheap behringer EP2500 which i could get for a little above 500£.
Do you think i could find a diy-amp schematic that would be even cheaper? with the same kinda amount of power? i have access to the equipment needed to design and create pcb's.

Øyvind

[AndrewT]

Hi,
buy a stereo amplifier that is capable of driving 4r0.
It should be able to perform well into an 8ohm driver.
connect the DVC in series to give an effective 8ohm driver.
connect one channel to one 8ohm voice coil.
feed a double mono signal into the two channels of the amplifier.

Alternatively,
buy a four channel amplifier (or 4mono blocks or two stereo).
connect one amp channel to each separate 4ohm VC.

But do make sure that the amp can properly drive 4ohm speakers.
Check its output into 2r0. It should be at least 160% of it's 4r0 power, preferably 180%.

[skogs]

here's the specs for the .behringer i mentioned. (see spec sheet)
as you can see the power at 2ohm is about 150% of the power at 4ohm. bad sign?

so you dont think i would get better of building an amp?

thanks for the tipses by the way i didnt know that one can use one channel per VC, i can see if i find something there

[AndrewT]

so you dont think i would get better of building an amp?

I think you can do a lot better building your own amplifier, but it will cost you a lot more. Unless you have a source for good quality cheap parts. Case, transformer, smoothing caps, & heatsink cost the most @ ~15% to 20% each. The amplifier and hardware components take up the slack.

[badman]

Originally posted by skogs
here's the specs for the .behringer i mentioned. (see spec sheet)
as you can see the power at 2ohm is about 150% of the power at 4ohm. bad sign?

so you dont think i would get better of building an amp?

thanks for the tipses by the way i didnt know that one can use one channel per VC, i can see if i find something there

Well, not necessarily a bad sign, but it does mean that the power supply and/or output stage (and cooling!) aren't as strong as they might be.

2 ohms is a pretty rough, current hungry load, so I wouldn't give too much credence to that unless you're really planning on using that kind of output power. Many subs hit Xmax limitations well before the amp/driver run out of thermal handling.

[skogs]

i definatly wont go for 2ohm. im thinking the more resistance the better. i believe its worth the ekstra money bying an amp that can give me the power i need in 4 or 8 ohms, rather than 2.

do you think the amp i referred to, the behringer, is capable of delivering 2*4-500 strong real Wrms@8ohm? it says on the spec sheet that the amp will drain 5A. 5A*230V = 1150W. guessing it got somewhere around 70% efficency that gives about 800W. so 400W to each channel. what do you think?

so diy-ing an amp will provide a better amp for the money, but wont be possible at such low costs as the behringer? thats when i want that kind of power.

thanks for the help people!

[AndrewT]

Hi,
someone is misunderstanding my message.
I am not saying that the VC be connected as 2ohm loads

I recommend that you keep the driver impedance high.
But the effective impedance seen by the amplifier is far below the nominal impedance.
As a guide to how well the amplifier can deliver current into your nominal load, look at the current ability into a resistive load about half the impedance you intend connecting.

If the power delivery (=current) into a low resistive load is good, then that is one of the indicators that the amplifier can drive the reactive speaker load well.

If you intend connecting the speakers as 8ohm loads then look for a good 4r0 power delivery.
If you intend connecting the speakers as 4ohm loads then look for good 2r0 power delivery.
My method is:- expect about 180% of power into half the intended load resistance.

[skogs]

Thanks alot Andrew
much i didnt know and didnt think of here. so the actual power delivered from the amp to an "8ohm" impedance connection will actually be higher than what the amp is supposed to deliver at 8ohm, because the load is actually lower.

then ill just go for the behringer. its supposed to give 450W@8ohm and 650@4ohm. then i could expect that the driver with VC in seires (8ohm) will recieve some 5-600W. and that should be plenty

thanks guys you have given me a new perspectiv on relations between driver and amp. how can i predict the actual resistance that the amp will see more accuratly?

[AndrewT]

Hi,
the Behringer will not blow up when the speaker demands more current than expected by an 8ohm speaker.
It will still be a 450W into 8ohm amplifier.

[sreten]

Hi,

Bridge the Behringer and drive the two coils in series. You will get 1.5kW.
As bridged output into 4 ohms is 2.5kW, AT's 160% criteria is met by 7%.

/sreten.