which would be better for ported... - Page 9 - AVS Forum
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DIY Speakers and Subs > which would be better for ported...
wormraper's Avatar wormraper 06:15 PM 10-01-2013
Quote:
Originally Posted by andyc56 View Post

For the unbalanced version that WR has, there's two possibilities:

With input sensitivity jumper set to 0.9 Volts RMS, the voltage gain is 1x = 0 dB
With input sensitivity jumper set to 2.0 Volts RMS, the gain is 0.45x = -6.9 dB

IOW, if the current input sensitivity setting is 2.0 Volts, an increase in gain of 6.9 dB can be had by setting this jumper to the 0.9 Volt setting. Strictly speaking, this is really a "reduction of attenuation", as the gain is never greater than 1.

I didn't notice any jumpers or dip switches on the box itself. is that something I'd have to yank the cover off the box and check the guts of?

andyc56's Avatar andyc56 06:22 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

I didn't notice any jumpers or dip switches on the box itself. is that something I'd have to yank the cover off the box and check the guts of?

In the PDF manual, see section 2.4.2, "Input sensitivity selection".

To make matters somewhat more confusing, apparently the early versions of the board did not have this jumper and thus had fixed input sensitivity.

Edit: Oops, yes, the jumper (if present) would be on the board itself.
wormraper's Avatar wormraper 06:42 PM 10-01-2013
Well. The two jumpers WERE set to 2 volt mode. I switched the jumpers to the 0.9 volt setting. I'll let you know how it goes
andyc56's Avatar andyc56 08:39 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

Well. The two jumpers WERE set to 2 volt mode. I switched the jumpers to the 0.9 volt setting. I'll let you know how it goes

Cool! Hope it improves things. If all goes well, this should allow you to dial back on the AVR sub gain by about 7 dB.
wormraper's Avatar wormraper 10:22 PM 10-01-2013
Thank you soooo much guys! With those jumpers switched I'm at about 65%-70% on the amp gain and +9 on the receiver. No DDT lights on the amp and much more headroom
andyc56's Avatar andyc56 10:24 PM 10-01-2013
Woohoo! biggrin.gif
chalugadp's Avatar chalugadp 10:29 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

Thank you soooo much guys! With those jumpers switched I'm at about 65%-70% on the amp gain and +9 on the receiver. No DDT lights on the amp and much more headroom

Keep us updated on sq of that beast. Let us know if midbass slam comes in. What do you haveit crossed over. Remind me what your lcr speakers are ?
andyc56's Avatar andyc56 10:42 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

Thank you soooo much guys! With those jumpers switched I'm at about 65%-70% on the amp gain and +9 on the receiver. No DDT lights on the amp and much more headroom

I'd suggest you turn the subwoofer amp gain all the way up (so as to have the actual specified input sensitivity of less than 1 Volt RMS), then dial back the gain of the AVR sub output to compensate. This will give you the highest possible bass acoustical output.
wormraper's Avatar wormraper 10:45 PM 10-01-2013
Oh ok. I had turned the amps gain down to make sure I wouldn't see the DDT lights flash. With the amp on max I can see them flicker on powerful scenes. With it dialed to 75% or less on the amp they never turn on but if its OK to turn the amp all the way up I'll do that. It'll be amp on max. And receiver at +7 instead of +9 then
andyc56's Avatar andyc56 10:57 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

Oh ok. I had turned the amps gain down to make sure I wouldn't see the DDT lights flash but if its OK to turn the amp all the way up I'll do that. It'll be amp on max. And receiver at +7 instead of +9 then

What you're doing would usually be just fine, but the difference between the lowest achievable amp sensitivity (highest gain) and the absolute highest output from the line-level circuitry of the unbalanced miniDSP is very small indeed because of the the miniDSP's relatively low maximum output voltage of 0.9 Volts RMS.

So the safest thing is to crank the amp to max gain (which will make the actual input sensitivity equal the specified value of, as I recall, 0.775 Volts or something close to that) and back off on the AVR output just a little to compensate. Hope this makes sense.
wormraper's Avatar wormraper 11:02 PM 10-01-2013
OK. Then its OK to see those DDT lights flicker on the amp then? Cuz with it adjusted that way they DO light up on some heavey hits
wormraper's Avatar wormraper 11:12 PM 10-01-2013
Quote:
Originally Posted by chalugadp View Post

Keep us updated on sq of that beast. Let us know if midbass slam comes in. What do you haveit crossed over. Remind me what your lcr speakers are ?

Sorry I missed your reply. The things sound phenomenal and as every hour goes by the coils are loosening up and they're really coming in to their own. I may be biased about midbass slam since I had twin thts and those things are unbeatable for mid bass
andyc56's Avatar andyc56 11:27 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

OK. Then its OK to see those DDT lights flicker on the amp then? Cuz with it adjusted that way they DO light up on some heavey hits

I'm not sure what the DDT lights are. Can you point me to a doc that describes what they do?

If it's amp clipping, that says the upstream circuits are doing their thing. From another POV, the upstream circuits should not limit what the power amps can put out. And if the power amps are being stressed, that says you need more of them and/or more subs. biggrin.gif
chalugadp's Avatar chalugadp 11:30 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

[quote name="chalugadp" url="/t/1488182/which-would-be-better-for-ported/240#post_23793178"]Keep us updated on sq of that beast. Let us know if midbass slam comes in. What do you haveit crossed over. Remind me what your lcr speakers are ?[/quote]Sorry I missed your reply. The things sound phenomenal and as every hour goes by the coils are loosening up and they're really coming in to their own. I may be biased about midbass slam since I had twin thts and those things are unbeatable for mid bass

So overall they are an upgrade or too early to tell ?
wormraper's Avatar wormraper 11:32 PM 10-01-2013
The DDT lights are the limiters to prevent clipping

Oooooh add another two in the front should do it smile.gif
andyc56's Avatar andyc56 11:45 PM 10-01-2013
Quote:
Originally Posted by wormraper View Post

The DDT lights are the limiters to prevent clipping

Oooooh add another two in the front should do it smile.gif

LOL. Okay, then if these light up when they didn't do so before, it says you now have enough input voltage to make that happen. That's a good thing! So then you should look at the limiter settings to make sure they're not too conservative. If they're appropriate, then you'll need some reinforcements. biggrin.gif
chalugadp's Avatar chalugadp 12:03 AM 10-02-2013
Quote:
Originally Posted by wormraper View Post

The DDT lights are the limiters to prevent clippingOooooh add another two in the front should do it :)

How many Watts is each sub getting ?
wormraper's Avatar wormraper 12:07 AM 10-02-2013
Lol. I have a 12 foot wall so two more would fill up up the front wall soooooo smile.gif
wormraper's Avatar wormraper 12:07 AM 10-02-2013
About 820 watts each at 4 ohm
chalugadp's Avatar chalugadp 12:26 AM 10-02-2013
Quote:
Originally Posted by wormraper View Post

About 820 watts each at 4 ohm
So my 1100 Watts should not trip any lights hopefully eek.gif
wormraper's Avatar wormraper 01:19 AM 10-02-2013
Quote:
Originally Posted by chalugadp View Post

So my 1100 Watts should not trip any lights hopefully eek.gif

Lol. You should be good. I was PUSHING these things to insane levels and the limiters were JUST flickering on seriously heavy beats. Were talking about the "ow I'm never gonna listen to these levels" type of thing
Martycool007's Avatar Martycool007 05:42 AM 10-02-2013
Wormraper- I have enjoyed reading your build. Mine will be finished up tomorrow night! How are you liking these Marty Sub beast so far?
wormraper's Avatar wormraper 05:52 AM 10-02-2013
Quote:
Originally Posted by Martycool007 View Post

Wormraper- I have enjoyed reading your build. Mine will be finished up tomorrow night! How are you liking these Marty Sub beast so far?

INSANELY well. these things are BEASTS... especially with a pair of them. they can eat up a good deal of power and bring the walls down. such an easy build.... to the extent I'm actually considering to make my pair a full set of 4 to line the front wall biggrin.gif

I haven't even broken in the drivers before installing them so they still have a lot of loosening up to do and they sound phenomenal.
nograveconcern's Avatar nograveconcern 07:42 AM 10-02-2013
"DDT senses clipping (or current limiting) and reduces the gain to prevent audible distortion."

Peavey's DDT is more like compression than just a clip indicator. The DDT light comes on several DB before clipping and begins to compress the signal so as to not hard clip.
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