Boston Acoustics GTA-802 going into "thermal protecion"

Unless your really committed to the "watt wace" (get it? I crack myself up), use the amp in stereo and connect one channel to each voice coil.

I've read some posts that have claimed that this isn't good because the voice coils will "fight" one another (one VC gets angry and runs home to mother, the other drinks a case of beer and wrecks the car on the way to the 7-Eleven for beef jerky), or work against each other (one VC steals the other VC's password and deletes a time-sensitive email from their boss). Not so. Dual voice-coil speakers have been used for years in custom home installations with no problems whatsoever, and they function at frequencies where there are significant difference between the channels. That isn't the case with the frequencies that subs typically deal with (which is why so many mono amps can "sum" the channels and why a single home audio sub works with an un-encoded stereo source). In fact, many, if not most electronic crossovers and HU's with dedicated sub-outs provide a monaural output to the subs so they can be used with a non-summing mono amp and a single sub like this one, or this one, or even this one. Phase cancellation isn't an issue either, because if it's going to happen it will happen whether the signal is summed at the crossover, at the amp, or at the VC's. Out of phase is out of phase.

Plus, the vast majority of recordings are mixed to mono below about 100Hz anyway. This was originally to reduce mis-tracking when playing vinyl, and it continues today because there is no advantage to mixing such low frequencies in stereo. Panning such low frequencies would have no audible effect except reducing the overall low-bass output.

Hahaha that was some entertaining informational overload (like when your girl gets furious and starts throwing things but then happens to tell you she's preggers during her childish rant).

1.  The enclosure was made by Boston - should I open it up and attempt to connect it as you so elequently described above? 

OR

2. Shell out an extra $50 (not an issue) for the Boston 400M and be able to run all the power to the sub as I envision it was intended.

Sincerely appreciated,

Zack

Alex is entertaining - but this is one time I am going to disagree with him.

ZB113705

Hahaha that was some entertaining informational overload (like when your girl gets furious and starts throwing things but then happens to tell you she's preggers during her childish rant).

Hopefully that doesn't happen to you TOO often!!!

Okay - seriously - from what I can tell your enclosure is 300W RMS DVC-4-ohm wired for 2-ohms final at the single set of box terminals.  (Although one site lists it at 300W peak, 75W RMS ???)

Your amp is:

• 80 watts RMS x 2 at 4 ohms (130 watts RMS x 2 at 2 ohms)
• 260 watts RMS x 1 bridged output at 4 ohms (4-ohm stable in bridged mode)

As you said, the amp won't work bridged to the sub as you have it configured.  You have four options:

• Run the sub off one channel as you have it now, but the amp will only supply 130W to the sub - and it is over-heating, although it shouldn't.
• Run the sub with one voice coil per channel as Alex W recommended - each VC will get 80W RMS - but it isn't recommended and would require you to re-wire the sub and add a second terminal cup to the box.
• Wire the voice coils in series for 8-ohms final at the amp and bridge the amp.  You still only get 160W RMS to the sub, and you still have to re-wire the box, but you don't have the (real or theoretical) problems with the voice coils not seeing the same signals.
• Swap the amp for the 400M (or any other 300W RMS at 2-ohms amp), which is probably your easiest solution if you don't mind the cost.

Hope This Helps!!!

Anyone else have suggestions?

TigerHeli

Alex W

I thought the enclosure had twp pair of terminals so it would be any easy switch. My bad.

Even if it did - you get the same power out of the amp with the amp bridged at 8-ohms as you do with the voice coils stereo at 4-ohms and you avoid the above problems with one VC going to 7-11 while the other steals your paycheck. 

Maybe so. But i don't see a problem either way. I guess some of us just don't have much faith in the amiable and reliable nature of voice coils. I allow several of them to stay in my home (although I do keep them separated) ...hey! Where's my wallet!?

Thanks guys I really appreciate the help.  Yeah the box only has 1 set of terminals, and i know I'll F it up worse than an Italian Cruise Ship captain if I get in there and start hooking wires up to everything.  New amp it is I conclude.

Will this be a good combo or should I be looking at another mono amp?

Boston 400M x1 @ 2ohms and Boston G210 @ 2ohms in a stock Bose system 2009 Cadillac SRX

-Zack

The 400M is fine, but any of these amps would be fine also.  Ideally you want a subsonic filter with the ported box - which the 400M has and some of the amps I listed don't have, but you don't have one with the 802 either ...

Hope This Helps!!!

Anyone else have suggestions?

Alex W

Unless your really committed to the "watt wace" (get it? I crack myself up), use the amp in stereo and connect one channel to each voice coil.

I've read some posts that have claimed that this isn't good because the voice coils will "fight" one another (one VC gets angry and runs home to mother, the other drinks a case of beer and wrecks the car on the way to the 7-Eleven for beef jerky), or work against each other (one VC steals the other VC's password and deletes a time-sensitive email from their boss).

LOL!!!! 

Tiger's answer is more correct for this circumstance, however.

we need a 'like' option!  5 stars Alex just for the belly ache.

added:  i hope it's not my light bulb post you are referring to, cuz i stand by it

Then we shall agree to disagree, good sir. Methinks...no...let's not go there...I think it has been overthunk. Odd that I'm the one professing "real world" application and the lot of you aficionadus mobilicus electronicus are standing on theory. Proves that the electronics gods have a sense of humor, I suppose.

is that a yes?  i don't care what you say, that was a good analogy!!

i rarely use theory for car audio, as making such assumptions diminishes my income.  i assure you, sir, that any advice i give on the forum is based primarily on real-world experience (tho i often reference more intense mathematical calculations off-site). 

i still find myself unable to inject the amount of humor that you routinely do!

J Ro

is that a yes?  i don't care what you say, that was a good ananlogy!!

i rarely use theory for car audio, as making such assumptions diminishes my income.  i assure you, sir, that any advice i give on the forum is based primarily on real-world experience (tho i often reference more intense mathematical calculations off-site). 

i still find myself unable to inject the amount of humor that you routinely do!

Hail fellow well met, the analogy was illuminating, to be sure, and your avatar surely injects more humor into the forums than I could ever hope to do through wit.

Sorry, couldn't resist.

I'll be the first to admit that there are times when the stuff that happens trumps the stuff that should happen. I've had quite a few "F**k me, really?!" moments over the years. Some of which I still cant explain. Most of them involve car stereo.

But I'm still right, ya know, theoretically speaking.

I'm not sayin', I'm just sayin".

God, I love this forum.

maybe you shouldn't be a mod...but i loves ya!!!

Ahem - back on topic ....

I going to throw a bit of a bone at Alex W and say that it can be done - for example - the OEM Shaker 500 and Shaker 1000 systems by Ford - one or two DVC subs with each voice coil powered by SEPARATE amps.

Doesn't mean it's a good idea, and in a practical case like the above - you get the same output with each voice coils on separate channels as with the amp bridged and the voice coils in series, and you avoid potential problems (whether they are likely or not), and you simplify the wiring.

The ONLY times I probably WOULDN'T recommend doing that and would power the VC's separately:

• If someone has a 4-channel amp and a DVC-4-ohm sub and they want to bridge the amp to two channels (poor amp choice for subwoofers, but it happens).
• For whatever reason, someone ends up with two amps that are about 1/2 the RMS of the sub and match the VC resistance, and for whatever reason doesn't want to sell them and get something that would really work properly.

Hope This Helps!!!

Anyone else have suggestions?

There are a lot of full range speakers with dual voice coils that are intended to be uses with left channel input to one VC and right channel to the other.

http://www.retrosoundusa.com/products/category/id/8

This line from Elan includes a dual voice-coil in-wall sub.

I haven't heard the Retro's but the Elan stuff works well and sounds very nice. Sonance, Speakercraft, OnQ and others make similar speakers. With the possible exception of the Elan sub, all of the woofers in these operate at frequencies where the left and right channels will carry different signals. I certainly agree with you both on following the manufacturers wiring recommendations with car subs, but I don't see any practical reason why the subs wouldn't work when connected to stereo channels other than a loss of overall output if the lowest frequencies of a recording were panned. There is no reason to do so because of the omni-directional nature of those frequencies (which is why it we don't have to center a subwoofer in a listening space.

And I used little starry things, just like The Daily Show. I'm not responsible for what your tawdry imagination f***s in.

No a mod, indeed. What a foolish notion.