Newbie Amp Impedence Question - SI BM MKIV / XDI 1100.1

Hi there,

Some of you may (probably not) know me from DIYMA as moodue.

I have the Audiofrog GB 10/25/40s powered by two Arc Audio xdi 600.4's in my BRZ. All good there.



The problem I have however is I bought a Stereo Integrity BM MKIV to be powered by an Arc Audio xdi 1100.1.

I feel like I dun goofed. :daniel:

The SI is dual 4 ohm. The 1100.1 is rated as follows:

1 Channels @ 4 ohms- 350 Watts
1 Channels @ 2 ohms- 600 Watts
1 Channel @ 1 ohms- 1100 Watts


I didn't see anywhere in the manual, but can I assume it would run at 225 Watts @ 8 ohms? That seems like not quite enough power.

600 seems like overkill. Specifically, a comment I saw on tundratalk left me worried enough to make this post..

Quote:

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...I had asked Nick if 500 rms is too much, he said yes, left it at that...

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There are plenty of other posts all over the internet about just watching the gains when "overpowering" a sub. I don't mean to open up a can of worms. Just looking for peace of mind before I wire this up and finally give it a listen!

What do?

If it was my gear, I would run it and be careful with the gain.

Parallel and leave gain all the way down might be worth a try , if wired in series @ 8 ohms does not seem sufficient ?
https://www.sonicelectronix.com/item...a-V124DV2.html

Use a different sub ?

If your car has a top speed of (super fast) but you only have tires rated for (kinda fast) then you drive kinda fast and don't worry about it.

Just because your amplifier could output (whatever) watts doesn't mean you have to output (whatever) watts all the time.

Wire coils in parallel and be a little conservative with your gain knob and your listening.

I have 150 to the 10's and 25's. 300 to the 60's. And now I'll do 600 to the BM. (I swear I'm not over-compensating for anything :whistle: )

But currently all of my gains are at min and they might stay there.

I'll be sure to do a proper tune with the DSP.3 before blasting edm music through it.

Quote:

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Originally Posted by moo

Hi there,

Some of you may (probably not) know me from DIYMA as moodue.

I have the Audiofrog GB 10/25/40s powered by two Arc Audio xdi 600.4's in my BRZ. All good there.



The problem I have however is I bought a Stereo Integrity BM MKIV to be powered by an Arc Audio xdi 1100.1.

I feel like I dun goofed. :daniel:

The SI is dual 4 ohm. The 1100.1 is rated as follows:

1 Channels @ 4 ohms- 350 Watts
1 Channels @ 2 ohms- 600 Watts
1 Channel @ 1 ohms- 1100 Watts


I didn't see anywhere in the manual, but can I assume it would run at 225 Watts @ 8 ohms? That seems like not quite enough power.

600 seems like overkill. Specifically, a comment I saw on tundratalk left me worried enough to make this post..



There are plenty of other posts all over the internet about just watching the gains when "overpowering" a sub. I don't mean to open up a can of worms. Just looking for peace of mind before I wire this up and finally give it a listen!

What do?

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I'm with Justin Zazzi on this, just because you have "too much" power running at 2 ohms doesn't mean you have to use it all. I'm running two 1000 watt rms subs with two 3000 watt rms amps with the gains set to produce 1800 watts rms each. I'm certain you can limit your amp to 500 watts pretty easily.

The only time that an amp puts out full power is if you're doing test tones at full volume, or doing some type of SPL burping. You'd be surprised to find out that during regular listening, it's probably putting out closer to 80w. As others have stated, keep your gains, volume, and EQ conservative, and you'll be fine.

BTW, I'm running a 200w per channel amp on tweeters that are designed to handle 80w and mids designed for 20w max. It's called "overhead" ;)

I think your answers have led me to an area that I haven't done enough research during or prior to this install. (my first active and 2nd install ever after a decade long hiatus).

I need to follow a more methodical plan to set gains and to set an upper limit for volume on my stock HU. I tend to like my music loud but I don't want to play Russian roulette with this gear.

I've been taking it easy on the AF's but I initially only set the channel gains through the Helix software just to make sure I wasn't distorting the signal with a (I think) 0db test tone.

I have yet to do a proper tune though. I need to acquire a measurement microphone. And clearly I need to read up some more on this whole process.


Sorry to get a little off topic but I appreciate all the repsonses!

It will be fine with the amp at 2ohms, just take a touch off the gains and enjoy transients with headroom ����

Quote:

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Originally Posted by moo

I have 150 to the 10's and 25's. 300 to the 60's. And now I'll do 600 to the BM. (I swear I'm not over-compensating for anything :whistle: )

But currently all of my gains are at min and they might stay there.

I'll be sure to do a proper tune with the DSP.3 before blasting edm music through it.

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Don't get scared now.
I wouldn't think twice about wiring it to 2 ohms. My amp does ~1200 to a 700 watt sub. While I don't play woofer cooker at full tilt, I do everything else.

I am guessing with the dsp.3 putting out 6v leaving the gain all the way down might not be enough if you are really concerned.
I would just leave the gain all the way down on the amp and turn the output down on the dsp.3. Set it for the proper voltage for whatever power you want (30 volts for the recommenced 450w for the MKiv). Problem solved.

Be careful with the BM's. You will not be able to hear them starting to struggle until its too late and they bottom out and potentially ruin it.

Also from the old stereo integrity site

https://web.archive.org/web/20160308.../#tab-features

Does the BMmkIV need 450 watts to perform?
Absolutely not! The new BMmkIV is a very efficient subwoofer thanks in part to its XBL^2 enabled motor and it does not need every bit of its power handling limit in order to perform well. In its recommended enclosure volume of 0.5^3 sealed, the BMmkIV’s ideal power range is 200 to 350 watts.

Jdunk54nl ,

That should make it w3rk ! Nice !

8 ohm will work if you read through Jdunk54nl's post attachment . Box size determines power handling ?

T/S parameters show measured Re - 6 ohm , wired in series , so slightly more power output than @ 8 ohms from amp !

Thanks for the advice everyone!

I did a little more research and found how to calculate the ideal VAC out of the amp. The ideal power range listed on the SI website (cached) for the MKIV is 200-350 W for a .5 ft^3 enclosure.

So if I want to be really careful I can look for sqrt(350 x 2) = ~26 VAC out of the 1100.1 before I connect the sub.


Also I found a great post by Andy on the Audiofrog Facebook page about setting gains in an active system. Had to reread it 20 times to make sure I understood everything, but it made me much more confident to push it to the limit.... (limiiiiiiittttt!)



Sources:
Sonic Electronix Youtube
Audiofrog FB - Setting Gains with a DSP


Edit: aaaannndd I just noticed my posts per page count is way too low. Didn't even see the last two posts. :daniel:

Also I realized I put DSP.3 instead of DSP.2 that I have. Phew. These silly mistakes are why I worry about blowing shit up haha...

Quote:

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Originally Posted by Queef

T/S parameters show measured Re - 6 ohm , wired in series , so slightly more power output than @ 8 ohms from amp !

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Is this to say the impedance of the MKIV when wiring the DVC in series is 6 ohms? Not 8?

I don't quite understand all the math behind T/S params. So apologies if I'm dead wrong lol.

EDIT Measured resistance. Got it.

Follow up. Does it make more sense to use the 6 ohm Re or assume 8 ohm impedance in the formula above?

Quote:

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Originally Posted by moo

Thanks for the advice everyone!

I did a little more research and found how to calculate the ideal VAC out of the amp. The ideal power range listed on the SI website (cached) for the MKIV is 200-350 W for a .5 ft^3 enclosure.

So if I want to be really careful I can look for sqrt(350 x 2) = ~26 VAC out of the 1100.1 before I connect the sub.


Also I found a great post by Andy on the Audiofrog Facebook page about setting gains in an active system. Had to reread it 20 times to make sure I understood everything, but it made me much more confident to push it to the limit.... (limiiiiiiittttt!)



Sources:
Sonic Electronix Youtube
Audiofrog FB - Setting Gains with a DSP


Edit: aaaannndd I just noticed my posts per page count is way too low. Didn't even see the last two posts. :daniel:

Also I realized I put DSP.3 instead of DSP.2 that I have. Phew. These silly mistakes are why I worry about blowing shit up haha...

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Yup. I did this calculation for the ideal VAC for my JL 10TW3 which takes 400 watts but my amp puts out 760. I set it up like you did with the formula for 760 and it’s working/sounding great.


Sent from my iPhone using Tapatalk

Quote:

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Originally Posted by Jdunk54nl

Be careful with the BM's. You will not be able to hear them starting to struggle until its too late and they bottom out and potentially ruin it.

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Start out "safe" , learn sub , then work towards optimization !

Quote:

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Originally Posted by Queef

Start out "safe" , learn sub , then work towards optimization !

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I am assuming that is not whee the term "sub optimal" comes from?