Bobbo's sub build (pics) - AVS Forum
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post #1 of 25 Old 09-15-2012, 05:15 PM - Thread Starter
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Finally finished up my project. Special thanks to everyone that helped me out, and Jay1/WiSounds.

Figured I'd post some pics. It's a Peavey Low Rider 18" paired with a bridged Behringer EP2000. It's a 5.5 cube box tuned to around 32hz.. It's purely for music and parties.

I did all this on my porch and party room, definitely not a master wood worker or have done speaker work like this before. Yes I know things could/should have been done differently but turned out quite nice. Hits decent, though I think it overall needs some adjusting.. (will touch on that at the end)










4 cans of truck bedliner. Still have to put on the grill guard.


As I was mentioning earlier I think it needs some adjusting.. it hits hard, but not nearly as it should. Some songs it barely hits at all... (when my old sub would be going hard) It just sounds empty on a lot of bass heavy songs. I currently have the amp set up as follows.

Clip limiter on
Low cut filter 30hz (as opposed to 50hz)
Low cut filter on
Bridge mode on

The signal is coming from a home theater receiver "subwoofer out" through a thick subwoofer rca cable into a 1/4 mono TRS adapter, into the amp. The amp is hooked up to the driver using very thick copper stranded speaker wire.

Not sure where the issue is.. (maybe amp settings wrong / perhaps I need to use a speakon connector / maybe the box is at fault / maybe it's tuned all off)
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post #2 of 25 Old 09-15-2012, 08:59 PM
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Have you tried it with the high pass (low cut) disabled?

Where is it crossing over to your mains?

Is it properly level-matched with the mains?

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post #3 of 25 Old 09-15-2012, 10:15 PM - Thread Starter
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Quote:
Originally Posted by baniels View Post

Have you tried it with the high pass (low cut) disabled?

Have not tried that. Thought that was to protect the driver from damage.. meaning it will trail off under 30hz. Or am I confused?


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Originally Posted by baniels View Post

Where is it crossing over to your mains?
Is it properly level-matched with the mains?

Mains as in main speakers? I have no idea where it's crossing over... or if it's level matched. It likely isn't. How would I go about doing so.



One guy at diyaudio claims if it's really tuned at 32hz it's too low for this driver and box size. I need to up it to around 38hz. I'm going to do a sine sweep and see where it comes in at. Perhaps that's the issue? I chose 32 as I thought it was a good balance, and I didn't want it to be boomy...
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post #4 of 25 Old 09-16-2012, 10:02 AM
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congratulations on your build.

"guy at diyaudio claims if it's really tuned at 32hz it's too low for this driver and box size. I need to up it to around 38hz. I'm going to do a sine sweep and see where it comes in at. Perhaps that's the issue?"

that shouldn't be a problem. the difference in tunings will only be a db or so in the 40-60hz region.

even if the driver is a nominal 8 ohm, you should be getting 1300 watts or so from the amp and that should give you 125db or so, which is quite loud.

do you have your amp in bridged mode?

what are you using to send the signal to the amp?

Listen. It's All Good.
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post #5 of 25 Old 09-16-2012, 10:32 AM
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Sounds like you need to bosst the input signal. Very common when using a pro amp.
I use one of these: Aphex Systems 124A -10/+4 Audio Level Interface 124A
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post #6 of 25 Old 09-16-2012, 11:03 AM
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Tell us what receiver you are using. If no level matching has been done, it could be that simple. If your receiver has any sort of auto-setup process with an included mic, I'd start with that (see receiver's manual).
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post #7 of 25 Old 09-16-2012, 12:28 PM - Thread Starter
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Originally Posted by LTD02 View Post

congratulations on your build.
"guy at diyaudio claims if it's really tuned at 32hz it's too low for this driver and box size. I need to up it to around 38hz. I'm going to do a sine sweep and see where it comes in at. Perhaps that's the issue?"
that shouldn't be a problem. the difference in tunings will only be a db or so in the 40-60hz region.
even if the driver is a nominal 8 ohm, you should be getting 1300 watts or so from the amp and that should give you 125db or so, which is quite loud.
do you have your amp in bridged mode?
what are you using to send the signal to the amp?

The amp is in bridged mode. It definitely gets loud. Just not very deep and chest pounding. Which I know it can do.

I'm using some insignia receiver. It's garbage. I was thinking about ordering this http://www.amazon.com/Yamaha-RX-V371BL-5-1-Channel-AV-Receiver/dp/B004QQXDVC/ref=sr_1_3?s=electronics&ie=UTF8&qid=1347791322&sr=1-3&keywords=5.1+receiver or basically any good Amazon prime receiver.
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Originally Posted by Wrager View Post

Sounds like you need to bosst the input signal. Very common when using a pro amp.
I use one of these: Aphex Systems 124A -10/+4 Audio Level Interface 124A

Hmm...

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Originally Posted by baniels View Post

Tell us what receiver you are using. If no level matching has been done, it could be that simple. If your receiver has any sort of auto-setup process with an included mic, I'd start with that (see receiver's manual).

No level matching has been done. Yet my old sub with the same receiver hit very hard with no level matching..
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post #8 of 25 Old 09-16-2012, 12:33 PM - Thread Starter
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This is what others have said, diyaudio/yahoo. Leaning more towards my box being the issue.. I have no problem trimming the port size as well as adding polyfill lining for a larger enclosure.
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32 Hz Fb is pretty low for a Peavey Low Rider in that small of a box (it will have a very rolled off LF response), to get some kick out of it you should raise the tuning to around 38 Hz, if your box actually comes in at 32 Hz Fb, saw off a bit of the port shelf and test.

"Chest pounding bass" is generally 60-120 Hz, 32 Hz is more "pants leg flapping", a 38 Hz tuning in your box should give you a bit of both, but the low tuning you (may) have sacrifices both.
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5.5 is on the low side of the recommended enclosure size for that sub.
According to Peavy's FR diagram you're going to get peak output at 50-60hz, and it's going to fade from there to 40, and drop like a rock below that.

A LOT of modern music spends a LOT of time in the 40-50hz range, and the REAL low stuff in the 30's is very common in hip-hop music.

It's the low stuff you can really feel, the 30-40 range. And that sub in that box just isn't going to do much there.
It's not hard to look at Peavy's FR graph and see the comparison of different boxes: http://www.parts-express.com/pdf/294-301…

Looking at their 5.0 @ 37 example you see a peak at about 70hz, and a fairly sharp drop on the low side. It's down about 3db at 50hz and 5.5db at 40.
The 9.0 @ 30 doesn't really have a peak (good in terms of sound quality). It is close to flat from 50-80hz, down only a little over a db at 40, and only -4db or so at 30.
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post #9 of 25 Old 09-16-2012, 01:01 PM
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"This is what others have said, diyaudio/yahoo."

well, stop listening to the people at diyaudio/yahoo. :-)

the difference in the two tunings is a db or so. my guess is that you are not getting a sufficient signal to your amp.


Listen. It's All Good.
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post #10 of 25 Old 09-16-2012, 01:19 PM - Thread Starter
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Originally Posted by LTD02 View Post

"This is what others have said, diyaudio/yahoo."
well, stop listening to the people at diyaudio/yahoo. :-)
the difference in the two tunings is a db or so. my guess is that you are not getting a sufficient signal to your amp.

The box frequency tested at around 33-34hz.

The receiver allows increasing the "subwoofer" in increments of +1. Is that effectively increasing the signal? I'm going to pick up a new receiver regardless. I just found it odd that I would have to bump that setting up, yet this is not a normal sub amp I suppose.

Are the amp settings correct? low cut on, 30hz?
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post #11 of 25 Old 09-16-2012, 02:58 PM
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"low cut on, 30hz?"

yes. that would be appropriate.

most music with what seems like deep bass is actually hitting hard in the 40-60hz region and your sub should be dishing that out just fine.

if the sub isn't getting a sufficient input signal, it won't be outputting full power even with the gain knob turned all the way up. ideally, you should be getting the clip light to flicker a little during heavy playback. some consumer receivers don't output sufficient voltage for pro audio amps...two standards, go figure.

also, many modern recordings have the snot compressed out of them, so the dynamics are not nearly as good as some of the old school recordings. that might explain why some tracks seem to hit really hard and others are kind of lame.

Listen. It's All Good.
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post #12 of 25 Old 09-16-2012, 07:04 PM - Thread Starter
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It hits hard, don't get me wrong. Yet I just felt for what this is, it should really be chest pounding and deep. It sometimes sounds kinda flat and empty. Almost boomy.

I'm getting a new yamaha receiver so that should be out of the mix. If I have it turned pretty high the clip light does indeed flicker.
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post #13 of 25 Old 09-16-2012, 08:54 PM
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The Yamaha receiver won't help. My Yamaha couldn't drive my ep4000, just not enough voltage out of the LFE. You need something to boost the signal like an art cleanbox or what was suggested before. The light will flash on the amp anyway even if it's not loud. You send a clipped signal to the amp it will clip. Mine did the same thing. After you boost the signal it'll be much better.

Dan
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post #14 of 25 Old 09-16-2012, 10:37 PM - Thread Starter
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Originally Posted by saabracer23 View Post

The Yamaha receiver won't help. My Yamaha couldn't drive my ep4000, just not enough voltage out of the LFE. You need something to boost the signal like an art cleanbox or what was suggested before. The light will flash on the amp anyway even if it's not loud. You send a clipped signal to the amp it will clip. Mine did the same thing. After you boost the signal it'll be much better.
Dan

Ahh. I'm definitely not sending a decent signal. I'm running an unbalanced signal through my 25ft subwoofer rca cord into the pro amp. I ordered a booster. I'm just not sure how high to set it?

http://www.amazon.com/Rolls-MB15b-MB15-Promatch-Converter/dp/B0002IL4B4/ref=sr_1_1?ie=UTF8&qid=1347868637&sr=8-1&keywords=Rolls+MB15

this is what I grabbed.


Anyway something is definitely off with this current setup.. my old BIC vk-12 hits harder/deeper.. I really hope it's the signal and not so much the box/sub combo...
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post #15 of 25 Old 09-19-2012, 03:42 PM - Thread Starter
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Quote:
Originally Posted by bobbobobbo View Post

Ahh. I'm definitely not sending a decent signal. I'm running an unbalanced signal through my 25ft subwoofer rca cord into the pro amp. I ordered a booster. I'm just not sure how high to set it?
http://www.amazon.com/Rolls-MB15b-MB15-Promatch-Converter/dp/B0002IL4B4/ref=sr_1_1?ie=UTF8&qid=1347868637&sr=8-1&keywords=Rolls+MB15
this is what I grabbed.
Anyway something is definitely off with this current setup.. my old BIC vk-12 hits harder/deeper.. I really hope it's the signal and not so much the box/sub combo...

Received the signal booster/converter. Massive improvement. Much louder, far more aggressive. Much much more output where it used to clip before, as to now where it starts to clip. Question, how high should I turn the gain on this booster?? I'm finding it difficult how to match where to leave the gain on the booster, vs gain on the amp.

Some songs are still not very "deep", but it's getting there...
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post #16 of 25 Old 09-19-2012, 09:37 PM
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How did you confirm your tuning? What are your port dimensions?

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #17 of 25 Old 09-20-2012, 01:10 AM - Thread Starter
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How did you confirm your tuning? What are your port dimensions?

Rough measurement of 20.75" wide by 2.25" tall, 18" in depth. Ran a tone test of each frequency with a white dot on the cone, at 33-34hz the dot had 0 movement, slowly increasing in movement in either direction thereafter. Reversing the math, the tune would mean my box comes in closer to 5 cubes. Peavey claims small vented as 5 cubes @ 37hz tune for optimal design. Though upping the tune shouldn't make a significant difference apparently..? Perhaps I should tune to Peavey specs and reinforce the box.

The converter/booster has been great, the room is going to shake apart, but still with some songs it seems like I'm just not hitting those "lows" properly, or something. Whereas all my basic commercial subs with the same songs put out nice and deep, just not as intense. Or maybe it's the mid area I'm not hitting. I don't know.


[If it ends up being the enclosure is just too small for this driver (I can still return), I may look into this guy...
http://www.parts-express.com/pe/showdetl.cfm?partnumber=290-434
the reviews claim a box of 5-6 cubes is exactly what it needs. (though guess my tune is a bit low..)]
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post #18 of 25 Old 09-20-2012, 05:32 AM
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I don't mean to hijack but can anyone tell me what is the name of the booster needed to raise the voltage of a receiver in order to make it play nice with a pro-amp? What are these called and how much do they typically cost? Also, can they be purchased at any of the typical music/guitar dealers?
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post #19 of 25 Old 09-20-2012, 05:34 AM
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The driver will displace a bit, as will bracing. You may be a bit closer to 4.5 at this point.

Just for kicks, try inverting the driver. This will increase the airspace of the enclosure and be a relatively easy experiment to see if a bit larger of a cabinet makes an improvement.

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #20 of 25 Old 09-20-2012, 11:54 AM - Thread Starter
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Originally Posted by Martycool007 View Post

I don't mean to hijack but can anyone tell me what is the name of the booster needed to raise the voltage of a receiver in order to make it play nice with a pro-amp? What are these called and how much do they typically cost? Also, can they be purchased at any of the typical music/guitar dealers?

It goes by many names, but it is a signal converter. (you can type rca converter, balance converter, etc) It takes an unbalanced signal and balances it as well as boosts it. There is the aphex above, the rolls I purchased, the art cleanbox, many others. As long as it's powered, it will be sufficient. A music/guitar dealer might have them yes.
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The driver will displace a bit, as will bracing. You may be a bit closer to 4.5 at this point.
Just for kicks, try inverting the driver. This will increase the airspace of the enclosure and be a relatively easy experiment to see if a bit larger of a cabinet makes an improvement.

By my math with this tune I'm coming it at 4.9. I'm going to open the box and reinforce some of the walls with slat bracing, that 3/4 mdf seems to be too weak, I didn't really reinforce this box, could be causing vibration, cancellation. After lining the walls with polyfill I'll likely come in around 5 or so. As well I'm going to cut the shelf and increase to 37hz, as per Peavey's recommended. Unless I should leave it at 33-34hz?

I'll do all that and see where I sit. Then reverse the driver, etc.
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post #21 of 25 Old 09-20-2012, 05:01 PM - Thread Starter
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I'll do all that and see where I sit. Then reverse the driver, etc.

Cut the port shelf, reinforced the walls, lined the box with polyfil. Tune comes in around 38. Sounds loads better than when I first started. Thanks to all that have helped!

I hit the clip lights with even less power now.. not sure if that's good or bad. Anyway only thing I have left to do is dial in the amp vs signal booster. More signal gain less amp gain? More amp gain less signal gain?

Also.. still don't have a crossover... this thing is playing any and all frequencies.. ha. Anyone know of any cheap small standalone units?
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post #22 of 25 Old 09-20-2012, 05:18 PM
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Quote:
Originally Posted by bobbobobbo View Post

Also.. still don't have a crossover... this thing is playing any and all frequencies.. ha. Anyone know of any cheap small standalone units?

Didn't you say you were using a sub pre out from a receiver? Seems odd that you'd be getting a full range signal there. Maybe it is older and it assumes your sub amp has a low pass?

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post #23 of 25 Old 09-21-2012, 11:15 AM - Thread Starter
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I'm borrowing a nice 7.1 Yamaha now, it claims "low pass 200hz" on the output, yet I still hear quite a bit of high notes, sounds like a speaker.

Anyone have any ideas as to where I should be setting things regarding signal gain vs amp gain? (and now there's "bass" gain on the receiver itself) ahhhh

I clip quite a bit.. can this driver not handle the power?
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post #24 of 25 Old 09-21-2012, 10:26 PM
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any sub-out on a home theater amp should already be filtered for a sub. Some are fixed at 80 hz, others are adjustable.

As to gain turn your amp level controls all the way up, set your booster level control in the middle and adjust output with your receiver sub volume control. Not enough? raise gain at the booster.
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post #25 of 25 Old 09-22-2012, 11:18 AM - Thread Starter
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Quote:
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any sub-out on a home theater amp should already be filtered for a sub. Some are fixed at 80 hz, others are adjustable.
As to gain turn your amp level controls all the way up, set your booster level control in the middle and adjust output with your receiver sub volume control. Not enough? raise gain at the booster.

I'll have to look if it's adjustable. The rear plate claims 200hz low pass, which seems pretty high still..

Easy enough, I shall do that with the gain thank you!

The sweet spot sound wise is right as the clip lights flicker, wish I could go a bit more. All in all it sounds really great though.
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