Hey guys I have a Memphis 1100-d, which is a 1000 watt class d amp. It only has 1000 watts at 1 ohm. What speakers do I get to get 1 ohm? How many do I need? Please help me!!!!

Well, since it "only" has 1000 watts. Is this a 2 channel amp or 1 channel? That could make a difference in our answers.

A pair of 4 ohm dual voice coil speakers will do the trick. Wire the voice coils in parallel and wire the woofers in parallel for a 1 ohm load. Or, a pair of 2 ohm single voice coil woofers wired in parallel. Or, a single 2 ohm dual voice coil woofer with voice coils wired in parallel.

Jay

1000 watts rms or peak?

four 4 ohm subs will give you 1 ohm.

How about 4 8 Ohm speakers?

Well, you would probably get more bass than you really wanted out of two 4 ohm 12's wired in parallel as stated above. I am happy with one ten.

However, if it is a two channel amp and you bridge to one channel, you already drop the impediance in half. So two 4 ohm speakers wired in parallel to one bridged channel will be a 1 ohm load on the amp.

However, if it is a single channel amp, then you can go the two DVC 4 ohm subs to really maximize the amp.

Sorry guys, I forgot to mention:( It is a one channel amp. Oh, and by "only" has 1000 watts at 1 ohm, I meant that the only way I can get all 1000 watts is I have to have it at 1 ohm. I really like tight, clean sounding bass. What kind of speakers should I get? Thanks for the replies.
-Howie

If you want nice clean bass, I would recomment two 10's. If you really want to maximized the amp, get two DVC 4OHM subs as stated above. You should be happy with that. If you want more, then go for two 12's, but it will be pretty loud and you will probably rarely listen to it at that level. That also takes up quite a bit of trunk space.

AudioMan, thanks for your help. What tens would you reccomend? Thanks, Howie

Audioman
please explain what u mean here....

'However, if it is a two channel amp and you bridge to one channel, you already drop the impediance in half.'


i would like to comment on the below statement:

'If you want nice clean bass, I would recomment two 10's'

using 10" subs do not necessarily mean u will have nice clean bass....actually bass response and 'tightness' have little to do with the size of the subwoofer....

Kevin

What factors are involved in having tight bass?
-Howie

the first factor is knowing the application of the speaker and how u plan to mount it(in a box, in free air, etc..)..also, tight bass comes from midbass and up, so not from the sub as long as the system is designed properly and your not using the subwoofer for midbass...and that comes back to the application of the driver and how u plan to mount whatever woofer u get...
Kevin

Kevin, you just like to start $hit don't you? What I read from several sources, that if you take a two channel amp, and bridge it to one channel and hook up one 4 ohm sub, the amp sees a 2 ohm load. Assuming that is true, if you take the same two channel amp and hook it up to two 4 ohm speaker in parallel and bridged to one channel the amp will actually be looking at a one omh load.

Regarding the tigtness of the bass, I guess I was not very clear on what I meant. You can get 8's 10's or 12's to sound great, but I personally recomment 10's. They take up a little less space, and unless all you listen to is very heavy bass all the time, they should be more than adequte.

One 12 could do the job too, but since this guy wants to use his amp at 1 ohm, then he would probably get more DB out of two 10's than one DVC 12, all things else being equal (speaker brand, type, ect.)

Is this now sufficient?

AudioMan, what speakers do you recomend? I do want to still have room in my trunk (for the golf clubs:)). I don't listen to a lot of bass. I just want a good tight, clean sounding system. I also need to upgrade my other components. I have an Alpine cda-7894 and stock everything else. I'm in the process of building everything else up. I want to get good stuff, however I don't want to spend a ton of money on it. I just want a clean sounding system. What would you recomend for me? Sorry for so many questions.
Thanks, Howie

Howie, I wish I could could recommend a speaker brand for you, but everyone will give a different opinion on what they like. Your best shot is to go to a stereo shop and listen to the different setups to see what you like the best. It also depends on the type of music you listen to. Since you want tight clean bass, I would rule out a bandpass box (no flames Kevin). And if space is of great concern to you, a sealed enclosure can be a bit smaller than poted. Two sealed 10's with the power you are going to give them should be more than sufficient and will leave you with some trunk space. But you will need some pretty nice speakers to handle that kind of power. Unless you have a "hook up", it may cost you between $100-$200 per speaker.

But seriously, go to a local stereo shop and tell them what you have and what you are looking for. You can listen to subs with compariable power you are going to give them and see what is best for you.

Thanks man, I appreciate it.

'Kevin, you just like to star $hit don't you?'

AudioMan:
no i dont, and since it seems u think i do i wont comment on your reply to me except the statement above....there are MANY people that read this and other newsgroups who will read what u and others say and take it as gospel....u throw out OPINIONS that some may take as fact and u really dont give reasons WHY u say certain things....now U may understand what u mean but to a newbie (which honestly most of the contributors here are) what u say might be confusing....we are here to help and in my OPINION we do a better job by explaining WHY we have an opinion, not just... '10's sound best for tight bass,' etc....i meant no offence at all and its nothing personal, just want truth to spread and not myths.....
Kevin

As of now, I am now retired from the Audio Board. I will defer all questions to Kevin.


On a side note, does anyone know how to change a screen name? Mine is outdated.

Not trying to get on you Kevin, but you know so much more about things here that answers that would be sufficient to 98% of the general public don't seem to satisfy you. You would make a wonderful attorney, or talk show host.

JERRY, JERRY, JERRY :boobies

i took this conversation off the public forum....i also included info on the username in the PM....
Kevin

Clearly.......this sounds like childish bull$#!+ Audioman...work with kevin7909...find a happy medium....not against him or any other board member....you may be able to point something out that he has missed....or at least provide a valid argument against what he is saying....so the members on the board get the benefit of the conversation...you never know...

-Nathaniel

We have worked things out now. All is well.

Cool!

Originally posted by kevin7909
the first factor is knowing the application of the speaker and how u plan to mount it(in a box, in free air, etc..)..also, tight bass comes from midbass and up, so not from the sub as long as the system is designed properly and your not using the subwoofer for midbass...and that comes back to the application of the driver and how u plan to mount whatever woofer u get...
Kevin

Don't forget its not all the speaker; the other components play parts of various importance.

The amp should be considered not just for wattage, but more importantly for current. A heavy current rating (from a high quality amp) means the amp has much more control over the driver, and can easily overcome any back-EMF from the subwoofer.

(For Howie's benefit: a speaker is nothing more than a very simple motor. When a motor is actuated by an external force on its output shaft, it can be run in reverse, that is - it produces current. Likewise, when a subwoofer or any other driver has excursion from a signal, it has to bounce back to its resting position. As it does so, it produces a back-current that can introduce distortion to the amplifier output stage. This is back-EMF.)

High current was the major reason that Rockford Fosgate was the one to beat in the 1980's. Their old school designs featured fully floating 12V power supplies that were years ahead of the competition. While everyone else was making "power booster/amplifiers", Rockford was using their Power series amps to weld, run small appliances at trade shows, etc.

Once you have the driver and amp covered, you still need a good source to provide a clean signal so the amp has something to work with. The whole sound system has to be considered as a "system". Of course, as expensive as all this stuff is these days, you're well off just replacing the weakest links first. Speakers are a great place to start. You want great bass? I'd try a/d/s or Canton for the hifi category, JL or Diamond for midfi.

The size of your woofers isn't as important as the boomheads tell you. Surface area is the key to air movement, not woofer diameter. You can run four 8inch woofers and end up with better bass than a pair of 10's or even 12's. Forget the birdbath 15's. Remember that smaller diameter woofers are easier for the amplifier to control. A lot less mass for the voice coil to deal with. Faster transient response means your music will have a very perceptible advantage in responding to things like slap bass and drum hits. I don't like going bigger than 10's in any car I work on.

You'll find that enclosure size is critical. I have a pair of B&W DM602 series II speakers here at home, driven by an Adcom GFA555 amp. I use those two speakers - and only those two - as my home theater system. They have exceptional fidelity, and floor shattering bass. Playing "Going Back to Cali" through them was enough to get my downstairs neighbor to end a party early one night. Yet those speakers have nothing bigger than a 6.5 inch kevlar woofer in them. How does it work? Perfectly optimized enclosure. Hard to do in the doors, but easy enough in a trunk.

BTW: just because your amp works down to 1 ohm doesn't mean you should do it. That is an added safety margin in case your load should drop that far. (Impedance is not a constant, despite what some people think.) You'd be better off designing the sub configuration to be between 2 and 4 ohms. You'd end up with even cleaner power, as most amps work better with a bit of a load on them. At this time of the morning, I can't remember the details, but I'm sure Kevin can fill in the blanks for you.

Chuck, thanks very much. This helps greatly.:)

A little late maybe but what the hell, I'll throw my 2 cents in !!
First I have to say I disagree w/ Kevin about woofer size having to do with type of sound, Here's a fact about woofer size, ( as it pertains to car use ) different size woofers are built for specifically for different types of sound, smaller woofers equal tighter, snappier bass, being small the wave frequency they produce is smaller and higher..But it is impossible for a smaller woofer to be able to move as much air as a larger one (unless you can find one with an 8" excursion !!) Larger woofers being that they can move more air create air pressure (SPL) and VOLUME !!!
Howie, the different size speakers are the different tools you choose to perform a certain job, you say you want tight,clean bass - So you should buy some good 10's.. Oh and BTW , no matter how clean your 10's are that you choose 1ohm sounds like crap when you're going for SQ , not to mention it's very unsafe for your equipment... I've had amps that claim they're stable to 1/4 ohm, and after what I spent on them, you'd better beleive they never saw close to it.. Run your system @ 2ohm...

Originally posted by X'z95M3
But it is impossible for a smaller woofer to be able to move as much air as a larger one (unless you can find one with an 8" excursion !!) Larger woofers being that they can move more air create air pressure (SPL) and VOLUME !!!

... except where, as I mentioned above, your total surface area of multiple smaller drivers exceeds the surface area of a larger driver. I have heard properly tuned minimalist 6.5 inch car systems beat the pants off of 10 inch systems as far as quality. I have also heard dual 9 inch DynAudio woofers destroy single 12 or single 15 systems.

Ultimately Howie, what you need to consider is: do you want this system for you to listen to as you drive in your car, or for everyone else to listen to as you drive by or sit at meets? If its a stunt system, get the birdbaths and have someone do a proper enclosure. If you want fidelity, something that won't fatigue your ears after long listening periods, go minimal. If you want 12's, try for 10's. If you want 10's, see if you can do it with 8's. Where sound quality is concerned, less is better. Less power, but cleaner, and with higher current.(100 watts of a/d/s or old school Rockford can beat 250 watts of Alpine or 400 of Sony.) Smaller, high quality woofers, properly enclosed.

Here's a trick you may find useful:

You can achieve a 3dB gain in perceived volume by mounting a pair of matched woofers edge to edge in your enclosure. Just make sure the trim rings are touching each other. Don't try this with tweeters, as you can cause a loss of up to 10dB perceived volume by mounting them adjacent.

Chuck:
P=V^2/Z....the impedance of the driver changes with frequency as i am sure u know and at resonance the driver has the highest impedance and tends to wanna oscillate......u mention that we should get ' hi current' amplifiers but ideal current amplifiers have infinite output impedance and ideal voltage amplifiers have zero output impedance and really there is no need for hi current amps as car audio manuf. brand them unless you have a very low load impedance like was mentioned in a post above...for us to not track the impedance curve of the speaker being driven we want the output impedance of the amp to be as low as possible because EVERY car audio power amplifier is a voltage source..as long as u adhere to that rule then the subs back EMF will not introduce itself into the amps output stage and cause distortion...the amps output impedance is what will determine the control the amp has over the system..the reason is that when the cone moves the voice coil through the magnet's gap in the motor structure, an instantaneous voltage is produced and the low output impedance of the amp looks like a short circuit and stops the voice coil and as such the cone from moving.....please tell me what solid state amp on the market cannot control a woofers cone when used within its design limits.....u seem to think that well built solid state amps used within their design limits sound different based on how they control the speaker...they dont....Howie go buy your favourite amp....

X'z95M3:
its a fact, eh? please tell me where you get your information from...u can make just about any two subs of any size sound teh same in a car assuming your using them within teh lesser subs design parameters(excursion and power handling)...all they are doing is pressurizing the cabin....u have a misconception of where your 'tight' bass comes from in your system....its mostly from the midbass and up to tweeters....dont believe me, talk to a knowledgable acoustic engineer.....also, u mention 8" vs 12" ...the weight of the cone has NOTHING to do with the 'speed' of the driver when taken by itself...its the entire system u have to look at..here is an example...the new mini is much lighter than the toyota supraTT....which will win in a 1/4 mile race? the supra of course but its so much heavier...but wait..the motor is so much stronger....same with speakers....look at the entire driver before making blanket statements which are false....

Kevin

:clap:

Originally posted by m3howie
AudioMan, what speakers do you recomend? I do want to still have room in my trunk (for the golf clubs:)). I don't listen to a lot of bass. I just want a good tight, clean sounding system. I also need to upgrade my other components. I have an Alpine cda-7894 and stock everything else. I'm in the process of building everything else up. I want to get good stuff, however I don't want to spend a ton of money on it. I just want a clean sounding system. What would you recomend for me? Sorry for so many questions.
Thanks, Howie

Howie, it sounds like you are in the same predicament I was in just a few short weeks ago. I am no auiophile, but I really appreciate a great sounding system. I hope I can help in your selection process because I know you want the best, but there are extremes that don't need to be reached also. I went with the Alpine CDA-7998 head unit, but that won't majorly affect the system once you externally amp your speakers. I was dead set on the JL XR series components for the front and rears, but then I listened to the Alpine X-series stuff and found the midrange to be a bit more prominent. I thought this would be good considering I am putting a 10" sub in the trunk to round out the low end stuff so better midrange in the fronts was important. So I got the Alpine SPX-137A 5 1/4" two-way components in the front, the Alpine Type-R 6 x 9 two-way coaxials in the back. The rears don't need to be as great (and expensive) as the fronts since they are usually used for rear fill. I wasn't used to this concept, but when I thought about it it just made sense. Kinda like a home theatre system, or being at a concert. The salesman at Ovation (store here) said to think of the rears coming through the back dash, reflecting off the rear windshield and then making it to the back of your ear. They're just there to fill up the sound stage. Anyway, I went with one Alpine 10" type-R 4+4ohm sub and the MRV-F450 amp. Only one ten will leave more room in the trunk and it'll be plenty of low end, without being overly annoying. I went with that amp because the RMS wattage was matched greatly with their speakers. I didn't mean to get all Alpine stuff, but it just worked out that way. I was going to go with a Kicker L7 solo-baric, but the rms wattage was too high for the amp, you usually want them to match up. I later found a (more expensive) JL 5-channel amp which further proves the rear fill point while also providing a more powerful sub output. I can't remember the model number, but it put out 125W x 2 to the fronts, 25W x 2 to the rears, and 250W x 1 for the sub. The Alpine was 50w x 4 and 200 x 1 sub. The alpine was also cheaper and for most of us out there (not counting Kevin :awink: ) it will be more than sufficient. The JL XR's are extremely crisp and clear and I strongly recommend you check them out, but the Alpines were very comparable. I also suggest you check out etronics.com and onlinecarstereo.com for prices. They were comparable to ebay prices, but gave a better sense of security (hopefully not false!) since it wasn't auction type. Well, I hope this helps and like I was hinting at earlier, if you aren't in it for the gold medal competiton stuff, or if you aren't just trying to blow out your windows, most of this stuff is going to sound outstanding and you'll be more than happy with it.

Note to Kevin: I don't know very much about this stuff, but I wanted to give Howie the "everyman"s view on the subject. However, I really appreciate your expertise on these matters because I love learning more. I could read your posts all day, I love to hear the real technical, in-depth analyses, thanks for helping us. See ya.

THANKS for the clapping Nate and the compliment jkearns13...i really like alpine gear and your correct about the jl speakers....very very nice.....as i have said previously, i nearly bought a set of jensen amps(and a jensen component set BTW) but got the fosgates for a much better price.....
Kevin

Thanks guys for the help. Both the technical and the "everyman's" points of view were very helpful.
Thanks, Howie

Chuck:
i replied to your PM.....
Kevin

I had a very interesting PM round from Kevin before responding to this stuff. A lot of information here and the whole class needs to pay attention to his posts.


Originally posted by kevin7909
Chuck: ....u mention that we should get ' hi current' amplifiers but ideal current amplifiers have infinite output impedance and ideal voltage amplifiers have zero output impedance and really there is no need for hi current amps as car audio manuf. brand them unless you have a very low load impedance like was mentioned in a post above...for us to not track the impedance curve of the speaker being driven we want the output impedance of the amp to be as low as possible because EVERY car audio power amplifier is a voltage source....

True.

Originally posted by kevin7909

as long as u adhere to that rule then the subs back EMF will not introduce itself into the amps output stage and cause distortion...the amps output impedance is what will determine the control the amp has over the system..the reason is that when the cone moves the voice coil through the magnet's gap in the motor structure, an instantaneous voltage is produced and the low output impedance of the amp looks like a short circuit and stops the voice coil and as such the cone from moving.....please tell me what solid state amp on the market cannot control a woofers cone when used within its design limits.....u seem to think that well built solid state amps used within their design limits sound different based on how they control the speaker...they dont....

Kevin

Don't get hung up in the characteristics of ideal current or voltage amps. They are useful for mathematical analysis but one has to include in the analysis a parallel or series impedence (respectively) that accounts for non-ideal behavior. This impedence is not a single number but a complex function. For real world circuits it should account for non-linear behavior - for instance the power supply running out of current or the amp's output stage current limiter kicking in. After all, a true short circuit has zero impedence, meaning any non-zero voltage will drive *infinite* current through it! No amp - or the universe for that matter - can deliver that. :D

The output impedence of the amp depends on its ability to source & sink current. So when you mentioned it looked like a short circuit (actually a very low impedence), you're right - but only within the range of currents the amp can handle. Outside that range of currents, output impedence will rise & its ability to control the cone will decline.
Ultimately, you're adhering to sound (heh sorry) design theory, but we need to salt that with some real world conditions. Unfortunately, audio is always a compromise; you have to tug on the design until it gets close to the specs you want. Its kind of like trying to get a mostly square bedsheet to fit a mostly rectangular bed - you can get close but not perfect. I don't think we'll live to see "the perfect amp".

Basically, no one really makes an amp that truly sucks anymore, but they each have their strengths and weaknesses. I will always hold current up as a sign of stability and quality of the output stage and power supply. Even so, I believe the point you raised about the hi-current amps tracking the driver impedance is valid. I've never given that aspect much thought. It does explain why the old school handbuilt Rockford's were best used for subs instead of full range, as they weren't as "musical" as the others we used, like Proton.
Hmm. A long standing mystery (to me) has just been answered.

Thanks Kevin!

Class: there will be a test later. Please study.

Chuck:
i'm glad i could shed some light on this..it MIGHT be useful for everyone if u posted our PM's about this so they can get the full picture....up to u completely....
Kevin