Bc 3500

[cbreen 0]

Ok I'm getting 2 12ssa zcons dual 1ohm. I got a BC3500 what would be the best way to wire the subs to it and the best wire to use. I think I'll have planty of power i got one xs power 5100R and going to put a second battery xs power 3100 with a mechman alt. all in a 1998 honda civic.

[jcarter1885 995]

Go to www.the12volt.com and click on the subwoofer wiring tab.

[ChevyBoy95 15]

[cbreen 0]

Thanks for the help. know whats the best way to set the amp. do i just play with it till it dont clip

[burko 6]

http://www.soundsolutionsaudio.com/forum/topic/3704-how-to-set-your-amplifier-gain/

[cbreen 0]

Setting the gain the description above im putting 2 12 ssa zcons and 1crescendo bc 3500. going to run the amp at 1 ohm so it should put out 3875 watts. Know being that said the subs are 2250 RMS know when i set the gain should i go by the watts on the amp or the subs and being i have 2 subs do i x it by 2?

[Quentin Jarrell 671]

http://mediacdn.shopatron.com/media/mfg/9013/media_document/live_1/gainSetting.pdf?1342137466

Set it like the link above. You will have to figure out what voltage to set at using the amp's rms rating and your sub's Re

[95Honda 486]

None of those methods are reliable...

[Notorious97200 339]

Setting the gain the description above im putting 2 12 ssa zcons and 1crescendo bc 3500. going to run the amp at 1 ohm so it should put out 3875 watts. Know being that said the subs are 2250 RMS know when i set the gain should i go by the watts on the amp or the subs and being i have 2 subs do i x it by 2?

Don't worry about watts. Turn the gain up until it sounds bad, then go down a bit. and that's it ! Ir's how I have always done it.

Bass boost to 0, and remote on full. subsonic just under the tuning frequency of your box, and LPF under 100 Hz usually.

Good luck

[Quentin Jarrell 671]

If you want to get technical no method will be accurate bc output voltage will vary with input voltage, Re will vary with frequency and heat, and some music is made hotter than others.

We aren't trying to get output down to .000001 percent accuracy. Just trying to get to a close "manufacture's" rating.

[95Honda 486]

That's the thing, your not using re with test tones, you are using impedance. It doesn't change .000001 percent, it changes 100%-1000% over the range the enclosure is designed to operate. So if you use any methods that simply assume an impedance, you aren't a little wrong, you are a lot wrong... I am stunned JL even publishes that info.

The only way this method will work is into a non-reactive load. There isn't a subwoofer made that is non-reactive.

[Quentin Jarrell 671]

So please explain how you would go about setting the gain on this install

[95Honda 486]

Look, I am not making this stuff up. Model any alignment you have built and look at the impedance. You will never (99.9% of the time) see less than at least 50% variation over the bandwith you operate in, much moreso in a vented alignment. It is just the way things are.

How would I advise him to set the gain? No matter what he does he has enough power on tap to thermally cook those drivers. So no matter how he sets it he will have the ability to change something in the signal chain somewhere and get more power out of his amplifier than he expects. In other words, there is no bullet proof way to set the gain threshold on an amplifier that doesn't have some type of limiting circuit. You can arrive a setting that may be accurate, but only if you change nothing from then on, and that is impossible...

So no, I nor anyone else, can tell him how to set his gain to get an exact maximum level from the amplifier and have it always remain excatly that way. I just doesn't happen.

That is why these tutorials are bogus...

[Quentin Jarrell 671]

I fully understand you point. If the sub's inductance (re and inductance is interchangeable ad their formulas are the same) drops to .1 the amp will put out a Quadratic rating of 36,000 watts and at resonance the sub might be upwards of say 15 ohms then it would only put out a quadratic rating of say 240 (@60 volts)

But that is exactly why I said "manufactures" rating. Most manufactures use powercube or the similar which uses a load box. As I know you already know the meaning of "RMS".

By it's very definition the RMS rating should already take impedance into account being the proper testing methods use a reactive load.

I bet if you were to take the quadratic measurements at various points in the usable passband of the driver in use with the amp's hpf and ssf and averaged it would be close to just using a 50 hertz test tone.

[95Honda 486]

Re has nothing to do with inductance, it is the DC resistance of the voicecoil. The Re doesn't change with frequency.

"Re

This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the ‘DCR’. This measurement will almost always be less than the driver’s nominal impedance. Consumers sometimes get concerned the Re is less than the published impedance and fear that amplifiers will be overloaded. Due to the fact that the inductance of a speaker rises with a rise in frequency, it is unlikely that the amplifier will often see the DC resistance as its load."

-Taken from Eminence "Understanding Loudspeaker Data",

*Note the distinction between Re and Impedance (as impednace contains the reactive component)

Impedance is the measurement of resistance that changes with frequency due to the reactance of the voicecoil.

If you set anything by voltage level for power output and neglect a change in impedance you are making an error. This isn't my opinion, it's Ohm's law.

[Quentin Jarrell 671]

Ok lol you just said the same thing I said. You just copy and pasted what someone else typed.

I kinda figured you understood that RMS ratings take into account impedance as any manufacturer worth their salt uses a device with a reactive load to measure RMS, that a 50 hertz tone is just a mean figure to use.

But anywho since you can't help the OP or correct Jl's method, I'll stick to the engineer's method who have more knowledge than any of us can hope to have and have designed, built and sold hundreds of thousands of amps with out the problem of the pesky impedance thingy causing problems.

[95Honda 486]

Bro, I am not saying the same thing as you at all... I sited a reference.

I am saying that JL is incorrect. There is no correction for this.

Le is not interchangable with Re, completely different.

I am not talking about what makes up RMS. I am pointing out the fact that you cannot use a voltage reference for deriving power when impedance is unknown...

I'm saying the OP cannot set gain by voltage. That is the answer to his question. If somone tells him you can, they are wrong and will lead him to equipment damage.

You either get this or you don't...

Done beating the horse on this one...

[ChevyBoy95 15]

oscope it

[Quentin Jarrell 671]

I'm not arguing the definition of impedance. I'm fully aware capatance and reactance affects impedance.

Find a company that you find reputable and let us know who they set gains. If it's any different than JL s version then you will have a little to add to the conversation besides the definition of impedance. Which you have already beaten to death as you say.

[95Honda 486]

In response to O'scope:

Sure. But then again, this only works at one frequency... As soon as you change frequency you change impedance and power changes. Then it is pointless...

[95Honda 486]

I'm not arguing the definition of impedance. I'm fully aware capatance and reactance affects impedance.

Find a company that you find reputable and let us know who they set gains. If it's any different than JL s version then you will have a little to add to the conversation besides the definition of impedance. Which you have already beaten to death as you say.

If you can't make the connection that you cannot derive power using voltage reference with unknown impedance than you don't get Ohm's law. That's it.

[95Honda 486]

I will try and help with a picture:

Here is a plot from a medium dampened 4th order bandpass with a single 10" driver. Lets assume we are setting voltage threshold at 40V RMS. If we do this and set the gain a the 35Hz we will be running about 85 watts. If we don't change a thing, this same alignment will pull 145 watts at 50Hz because of the lower impedance. This is Ohm's law and the way it works. If you set your gain threshold with a certain voltage you most certainly will run into problems when the impedance drops. Not only due to the increased power to the driver, but do to the fact that almost all amplifiers do not act as perfect (they try and be) constant voltage sources into all rated loads. The rail voltage drops. You don't take this into consideration when setting to one voltage reference.

[Quentin Jarrell 671]

Yes again that's the same thing I said in the above posts. I even gave example impedances and voltages and wattages.

[Quentin Jarrell 671]

And if impedance is such a large factor in loudspeaker output. Wouldn't we see or notice a large drop in response output at the high and low impedance rises and drops.

I mean when a sub's impedance spikes at tuning wouldn't we expect to hear a large drop in output at tuning due to lose of wattage?

I'll bet if you set you gains by ear on a speaker and then figure wattage using voltage and Re it'll be close. That is of course if the speaker is in a enclosure that will allow it to play near thermal maxed levels without bottoming out.

[Quentin Jarrell 671]

And to give a quote from a qualified source. On page 63 of loudspeaker cookbook, using figures 2.3 and 2.4.

Quote "figure 2.3 compares the impedance curves,which are similar for all three alignments. Transducer velocity shows the peaks in driver acceleration to be roughly coincident with the impedance peaks, and minimum at the impedance minimum."

Now is the driver is getting so much less power at the high impedance spikes how is it that acceleration increases. One would think with that much less power caused by inductance of less than one ohm to over six ohms, that the driver would accelerate considerably less at a higher impedance(less power) than at lower impedance(more power)

Edited July 18, 2012 by Audibel Customs