xtant 403a oonfiguration blues

[axed]

has anyeone dealt with this amp? or any xtants?

it uses jumpers galore. and im an audio n00b. however, i was told it was a good amp so i baught it on ebay when i saw a decent deal.

my issue is with a sub. ive been trying to get a 12 inch sub (image dynamics idq v3) to work with it. at first i was stuck with no sound but now i do have sound except it doesnt sound right.

its just not loud.

i have the sub connected to the mono channel with speaker wires, and my headunit (alpine 9833) has rcas coming out of its sub output connections down to the amps rear channel.

i have my sub turned on and turned all the way up on my headuint (+15). i installed one of the low pass crossovers that came with the amp into it, and notched up the gain from 10db (which is how it came) to 20db. and now its decent. but i dont think i shoudl have to turn everything up like this for it to sound "decent"? do i?

i tried bridging as i thought maybe the sub wasnt getting enough power to it (its a 3 ch 400 watt amp) but i failed. the manual says to use the possitive of the left and the negative of the right but after doing this i got no sound, even after switching the 2/4 ch jumper around.

i guess this isnt your everyday amp, can anyone help me?

amp manual: http://www.xtant.com/html/techSupport/pdfs/403aMan.pdf
amp installers reference (bridging info, and layout of amp and its jumpers): http://www.xtant.com/html/techSupport/pdfs/403aIns.pdf

sub info (v3 isnt listed only v2 is but v3 is basically the same thing except given to dealers, cooler magnet): http://www.imagedynamicsusa.com/webs...ducts/idq.html
rms is 360, but guy i baught it from said they have crashed it with 1000+ and his is runing at 460, i trust his claims and he has a long and experienced history with audio, but refuses to touch friends products becuase he doesnt want to get blamed if something breaks. so im on my own.

someone, please help

[axed]

no replies eh?

well do any of you at least know of another forum (doesnt have to be e30 related but that helps) that i might find answers in?

[KenC]

Didn't see the thread.

Is the sub 2 or 4 ohms?

The amp is only rated at 100x1 @ 4 ohms in the sub channel.

[axed]

woops, sorry just realised the link for the sub is wrong, links to the xtant... link now fixed.

[KenC]

Is the sub 2 or 4 ohms?

[axed]

crap, dont know that... got the sub through a great deal through a friend.. ill need to go open it up and check the back for a labeling... as you can see on the website the d2 and d4 are the only dfferences in name and show it in the ohm rating. lets say its 2... and lets say its 4 give me what you would answer in both scenarios.

[KenC]

If it's 4 ohm, you're only putting 100 watts to it - pretty low for a sub of that stature. If it's 2 ohm you're putting 200 watts to it - respectable at best. The weak sub channel of the amp could explain the quietness of the sub. Your only quick fix right now is to crank the gains on the sub channel.

[axed]

what about bridging the sub?

the install reference says use positive of channel one and negative of channel 2. is it speaking about putting the speaker wires from the sub into + on 1 and - on 2 or the RCAs from sub to headunit? in other words, which wires do i switch around to make it bridged. and is wiring all thats necessary i remember putting the speaker wires from mono onto the bridged config.. but was getting no sound.

thanks for your quick replies

[KenC]

Oh, the subs are DVCs. You really need to find out if it's a dual 2 or a dual 4 before I give you anymore advice as the advice I would give to you if it was a dual 4 ohm would most likely damage the amp if the sub is actually a dual 2 ohm.
I wouldn't bother briding channels 1 and 2 to it. The 3rd channel will provide the same power output.

[axed]

ill go check the sub now, gimme 10 min. but why would bridgin the 2 channels not make a difference... i mean... its a 400 watt amp... the mono has 100 on a 4 ohm and 200 on a 2ohm... wheres the other 300-200 watts? or do you mena that bridging would also yeild a max of 200 watts to sub?

[KenC]

The amp is essentially a 4 channel amp with the rear two channels already bridged into one. The amp will produce 400 watts at 2 ohms, however, there is no way to channel all of that wattage to one speaker. The front two channels will produce 100 watts each and the rear sub channel will produce 200 watts.

[axed]

its theres a sticker labeled D2 on one of the power input areas... so according to this http://www.imagedynamicsusa.com/webs...ducts/idq.html

its 2 ohm

[KenC]

Ouch... since the amp isn't 1 ohm stable you're gonig to need to run the voice coils in series to create a 4 ohm load. In which case the sub is only going to get 100 watts in the 3rd channel. However, in this case you'll be able to get 200 watts to it if you bridge channel 1 and 2 to it (not sure what you'd do with the 3rd channel though...).

[axed]

well i could always put the rear speakers on the third channel since i was going to make those mono through the headunit.

but, now your saying i should bridge the sub?

how do i run my voice coils in series?

and why would i want to put a 4ohm load on a 2ohm sub?

sorry for the questions, im a bit confused becuase you said bridging wouldnt matter earlier and now you say i should bridge. plus im trying to educate myself... so far ive learned more in this thread then i ever knew up to this point.

[KenC]

Why would you want to run the rear speakers in mono? I'm not a fan of rear speakers at all for that matter.

When I use the word 'bridge' I'm referring to the amp. you bridge the amp to the sub. In this case, if you want to get maximum power out of that amp to the sub, you're going to have to bridge it.

in order to run the voice coils in series, you want to create only one path for the current to travel. On the sub there should be a positive and negative terminal on each side of the sub. Take one wire and connect it to the positive terminal on one side of the sub (this will be your positive lead), then on the OTHER SET OF TERMINALS (other voice coil) hook a wire up to the negative terminal (this will be your negative lead). Then run one more wire across the sub connecting the two remaining terminals together. Since both voice coils are two ohms, and you just wired them in series, you've created a 4 ohm load with the sub.

The sub isn't actually 2 ohms. It has TWO 2ohm voice coils. That is, you can either run them in series to create a 4ohm load, or in parallel to creat a 1ohm load. Since your amp isn't 1ohm stable, you'll need to connect the voice coils in series as described above to create a 4 ohm load.

I tried to spare you the physics of the impedence of the voice coils...

My advice is to get a new amp. The 403 isn't going to do what you need it to.