Would it be better to run two subs off a Mono amp at 1 ohm load, or 2 subs off a stereo amp at 2 ohm load on each channel. I have two alpine type-r 12's (the 05's) And i was hoping to run more power to them w/ the mono block, but then its a 1 ohm load, and from what I'm reading, amps don't last long (even ones that support a 1-ohm load) running at 1 ohm. I would just be at 500 watts a piece w/ the amps i'm looking at if i did a 2 channel amp, where as i would be looking at 700rms each sub if i did a mono block. But i can't afford to buy another amp in a year. Its gotta last. Oh, and I will be running them in a large ported box. Thanks in advance.
*edit* Also, I'm looking at an amp thats probably going to be (W x H x D): 18.11" x 2.5" x 10.3" I'm guessing that it probably wouldn't fit under the seat. If anyone knows that it will, that would be great, Does anyone see any obvious, good places for it. I've spent hours on the forums and nothing seems right.


-JP

JP -

I'm glad you're back. I was afraid I'd scared you off with stories of crazy San Francisco concerts in the '70s. Don't worry. My generation lived through it. In fact, right now we're running the country. :shock: And obviously, I personally had enough extra brain cells to loose. I can still tie my shoes and rarely drool on myself.

You are absolutely right about avoiding a 1 ohm load. A 1 ohm load will make any amp run very hot. There are two things an amp doesn't like: heat and water. Avoid those two and your amp can last you for years.

Let's also look at the difference between 500 watts and 700 watts. You are talking about a 1 dB difference in output. A whole dB. Not a lot. Here are the rules of thumb you want to use:

- 3 dB is a doubling of power, going from 500 to 1,000 watts, for example. It is also a 3 dB increase when you go from one watt to two, which is where you really get your changes in volume. Even if you like to crank your stereo, I'd bet that most of the time you are using less than 20 watts.

- 2 dB is a small increase in volume. If I was to play a stereo for you and then turn it up and you said, "Yes, that's a bit louder," that's a 2 dB volume increase.

- 1 dB is supposedly an inaudible increase in volume. I don't believe that. I do enough work (daily at this point) with third octave eqs that I can easily hear a 1 dB increase. Where it is inaudible is when you factor in time. If I was to play you a stereo, and then we turned it off and went for a walk, and when I turned the stereo back on it was 1 dB louder, you couldn't hear that difference. You'd say it is playing the same volume as before.

Are you willing to risk your amplifier blowing up for a difference of only 1 dB? I doubt it.

Now, if you said you were looking to buy one of two mono amps, one that put out 500 watts and another one from the same manufacturer that sold for a $150 more, putting out 700 watts, that's a different story. You don't play 1 ohm loading tricks to get that extra 200 watts in this case. You get it by the manufacturer building a beefier amp. Power equals current times voltage. More voltage, and especially more current, are good things. Not only will the system play louder but it will be punchier and more articulate. The bass will simply sound better. This I like. :)

OK, now back to your original question. Going back through your previous posts, I see you have the dual four ohm voice coil version of the Alpine Type-R subs (SWR-1242D). This means you want to buy a stereo amp that you'll bridge to mono. You don't want to buy a mono block.

Here's the math: You'll run the two voice coils on each sub in series. Your manuals will show you how to do this. Essentially, for each sub, you take the negative of one of the voice coils and jumper it to the positive of the other voice coil. You then hook up the remaining positive and negative leads to your amp. When you do this, you now have an 8 ohm sub (two 4 ohm voice coils in series equals 8 ohms). You then hook your two subs up in parallel. The positive and negative leads for each sub go directly to the amp. Two 8 ohm speakers in parallel will result in a 4 ohm load at the amplifier. But I've said you want to use a stereo amp bridged to mono. When you bridge an amp, it electrically sees half of the load the speakers present. To the amplifier, this 4 ohm load looks like a 2 ohm load. This is what you want. A 2 ohm load will still make an amp run hot but not extremely so. Provide for good ventilation and you'll be OK. Plus the amp will put out as much power as it can while staying stable. You'll get the best of both worlds - power and long life.

I drew you a diagram of this set-up:

http://img.villagephotos.com/p/2005-1/940070/ampspeakers.JPG

Before anybody else asks, if you had the dual 2 ohm voice coil versions of your subs, then everything would be the same but you'd then want to use the mono block amp you were considering. Two 2 ohm voice coils run in series make each woofer a 4 ohm piece. Hook up the two 4 ohm woofers in parallel and you get a 2 ohm load. The mono block is happiest driving a 2 ohm load. Again, the result is maximum power output and stability.

As for where to mount your big amps, and they are BIG, I'll let others answer that question.

- Gregg

I hate to go off topic but I have to ask. Outpost, did you go to Bill Graham's Winterland? I went to hundreds of show there in the 70's. That and the Cow Palace (Quadrophenia in '72, Floyd in '75). So many shows in so many places, even Snack Sunday at Kezar, Zeppelin too.

8-) That's crazy, Randy. You and I were at many of the same shows. I went to school at Stanford from '71 to '75. Traffic at Winterland in late '71 or early '72 was my first San Francisco show. Actually, my first college rock experience was an awesome ballet version of Tommy that was at Playland on the Great Highway (maybe at the old Avalon Ballroom?) in the fall of '71. The company put a Christian take on Townsend's opera, but that only forced me to figure out what Pete really meant the words to say with a guy across the hall in my freshman college dorm. I was at both that Quadrophenia show you mentioned, the one where Moonie passed out and the kid came out of the crowd to play drums for the encore, just weeks before the tragedy at Cincinnati, and the '75 Pink Floyd show at the Cow Palace. Wish You Were Here had just been released (I tell kids today of listening to Floyd when Atom Heart Mother was the new record :) ). I was also at the Dead's '74 Cow Palace show and the first two Days on the Green in '73 at Kezar Stadium in Golden Gate Park. The first Day on the Green was a great three set Grateful Dead concert, which was also the first Dead concert I "got", and the second one was a few weeks later with Led Zep. Is that the Zeppelin show you're talking about? Plus I, too, was at 1975's SNACK concert, also at Kezar. But you are right. Home was Winterland. Funky old Winterland. I can still see the Stones tongue and Steal Your Face banners that hung from the ceiling behind the stage, no matter what band was playing. We'd go up for a show many weekends. Tickets were $3, maybe less, and you could see three great bands. And half the time, the Sons of Champlin was one of them. :grin: At Winterland, I remember seeing Traffic a second time, Yes, early Starship (where Balin came out and joined the group for Caroline) and Santana. Plus the Grateful Dead again and again. 1974 was my year. I had loosened up enough to enjoy the scene completely, had a couple of jobs so I had money, and even managed to get my best grades at school. I keep trying to find myself in The Grateful Dead Movie, shot at Winterland in October of '74, as I was at four of those five shows, but I can't. Maybe a lack of documentary evidence is a good thing. :twisted:

We always showed up at Winterland the night before and ran to the center of the front of the stage. Great times. Always had fun in line too. Bill would show up and spend time talking to us asking what and who we would like to see.

What about getting a 2 channel amp that puts out 500rms x 2 at 2 ohms. I'd wire up the vc's on each sub in parallel to get a 2 ohm load on each sub, then run a channel to each sub. The amp I would be looking at using would be a Hifonics zxi1006 (http://www.etronics.com/product.asp?stk_code=hifzxi1006). Thanks for the help, you are a great asset to this site, and all that stuff.

Just curious, has anyone actually printed out the brouchures shen made and put them on peoples windshields? There's a lot of elements out here (I live in savannah, there are beaches and islands out here). It seems like all the people i see in E's are old stuck up people, young cool people, or crazy, yet cool, older folks(probably a lot like mine).

Thank you for the compliment, JP.

Either way would work but I think my way might play louder. Try it both ways. That's the beauty of car audio. You can play with it. Whichever way sounds the best and/or causes the amp to run the coolest would be the way you want it.

Yes, people put EOC brochures under windshield wipers all the time. :)

Ok, so after learning all this, I'm rethinking other amp possibilities. If you have any suggestions for about $250 shipped or less (including ebay) I would love to hear them. These are two that i've quickly found. How are MA's Amps? I've heard good things about Hifonics. It looks like if i wired Outpost's way the MA would be better (statistically) and if i wired my way the Hifonics would be better. Any thoughts/suggestions/comments?

MA Audio HK898 (http://www.etronics.com/product.asp?stk_code=mahk898)
Hifonics zxi1006 (http://www.etronics.com/product.asp?stk_code=hifzxi1006)
MA Audio HK989 (http://www.etronics.com/product.asp?stk_code=maahk989&store=&catid=308)