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Discussion Starter · #1 ·
I'm looking to do a boot build, got components and amp lined up but have a question regarding RMS power, with the amp and subs paired at 2ohm load, the power of the amp is 870w, the speakers want 450w rms a piece (x2) so 900 in total.

I have heard underpowering a speaker can cause damage as well as overpowering. Any audio experts know if this 30w (3.4% variance) will be damaging?
 

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You won't have a problem. Firstly, 870Watts RMS will probably blow your windows out... Are you sure that is the true rating?
Anyway, the important part is not to over power the amplifier (always have your speakers higher than the AMP). Speakers of this caliber start to respond at about 15-25 Watts RMS, anything lower simply means the diaphragm of the speaker won't function. I can't see how you can "hurt" a speaker with low power input (similar to turning the volume down). Hope it makes sense.. You should be able to see the response indicator within the speaker specification.
 

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There's no such thing as overpowering speakers. Yes you can set the gains too high and clip the hell out of the speakers but that's down to user error.

Using an amp that's rated higher than the speakers (RMS ratings, not max/peak power) is actually an advantage as you can set the gains much lower and as a result you get a cleaner signal going to the speakers.

Also bear in mind that cabling and crossovers etc all add to the resistance and although the the amp might be outputting 100watts RMS for instance, by the time it hits the speaker it will be lower than that due to the cable and crossover it passes through.

On the other side....using an amp that's rated too low for the speakers means you'll set the gains higher than necessary, meaning it'll work much harder and induce noise into the signal. If your not careful you'll send a clipped signal to the speakers.

At the top of my head my focals are rated around 80watts RMS and I'm using 150 watt RMS amp to power them. My sub is rated at 1000 watts RMS and so is the amp powering this but I never run it to the max as the front components can't keep up.
 

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Discussion Starter · #4 ·
So i'm lining up 2x hertz high energy 250s (SVC) powered by the DLS a6 amp, all paired at 2ohms which gives me my above dilemma of 870 v 900. Really want this amp as it has subsonic filtering, remote bass control and is all-round very well reviewed for SQ (what i'm going for) as are the subs. I am trying to find a second hand pair of the DVC versions but hard to come by (limited budget of £500) and from what i've found this combination was best value for money in terms of SQ.
 

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Hi DPMURPHY,

You are indeed right, the subs will wire down to two ohms to the amp and the total combined RMS power of the subs is 900wrms, and the amp will put out a theoretical 870wrms.

Filtering out what other people have said in this thread, putting 870wrms into the subwoofers will be fine

Lets rule out some myths here;

Under powering a subwoofer will cause it to blow - No not at all, what will blow a subwoofer is DISTORTION. This is achieved by setting the gain too high on the amplifier and causing it to send out a 'clipped' signal. This is where they signal isn't a sine wave anymore and is more of a straight pattern with upto 90degree edges. Sending 100wrms into a speaker designed for say 2500wrms is fine as long as the signal isn't clipped and full of distortion.

You may hear people will blow their subwoofers up with an amp that was less powerful than the subwoofer, this is mainly due to one main reason, the higher the subwoofer ratings go, they generally tend to be less efficient (this isn't always the case but most mainstream woofers follow suit), so in order for the sub to play louder, people will generally push the gain pot further not realising they are sending through pure distortion.

If you want more info let me know and ill carry on.

Overpowering a subwoofer will blow it - same as above, it will only blow if its sent a distorted signal. Obviously, there are limits and considerations to take here, will a crap JBL subwoofer rated at 200wrms take more than 500wrms, its doubtful for extended periods, however, its not the voice coil that will let go generally, its usually the mechanical parts of the speaker - spider, cone, surround, dust cap etc. However, give something like an Ascendant Audio Havoc which is rated at 1500wrms, 3000wrms of a perfect sin wave and clip free, and it laughs its head off.

My old Ascendant Audio SMD's were rated at 3500wrms, I gave them 9700wrms each daily use and they got HAMMERED! Never had an issue.

Again, let me know if you want more detail.

Swapping the amp from x wrms to another amp that does 50wrms more, will I notice the difference - Highly unlikely. The difference in power only really makes a difference if you are going from say 1000wrms to 1500wrms. As a rule of thumb, an amp needs to produce approx 250-300wrms more power before you hear the difference and even then, the difference may not be as big as you think!

What makes the biggest difference when swapping out amplifiers, are the amplifiers themselves. Use something like a JBL/Boss/Pioneer etc and then swap out to something like a Mosconi, Gladen Audio, LW Audio etc, if the power ratings are the same or similar, the main reason you hear the difference is because the quality of the components used on the board are far superior and produce a 'better' sound. A bit like why you choose a R32 over a Ford Escort...its just better!

Personally, if it was my setup and you haven't bought the goods yet, I would pick slightly different gear but thats me!
 

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Discussion Starter · #6 ·
Thanks for that detailed reply dude really appreciate it, would love to know more trying to learn about all this as I go. I have roughly a £500 budget all in (building the enclosure myself) and trying to preserve useable boot space.

Could I ask what you'd recommend?

I had my concern raised when the logic of 'the amp will be straining itself to meet the rms of the speaker' was mentioned which makes sense but didn't know if it was a reason to scrap my potential build and look elsewhere
 

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Discussion Starter · #8 ·
Haven't purchased anything yet just had the pairing of the hertz and DLS lined up due to some 2nd hand bargains on talkaudio forum. Always wanted a nice symmetrical build and thought 10s would be better for tight punchy bass (i listen primarily to metal) but didn't know if i might miss the lower end frequencies if i went for 10s over a 12. i did check out that thread think i might have PMd you about it (or i was intending to)
 

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Hi mate, I just logged onto TA now and saw your PM lol!

Personally, I don't like the sound of the Hertz speakers or amps...and be careful with DLS as there is no UK support now.

What sort of budget do you have for the subs and amp? If you are concerned about retaining both punch and lower end response, then something like the B2 Audio REF10 would be a perfect balance and work in tiny boxes. If they are stretching the budget a bit too much, then look at the Gladen Audio SQX10s, they are great all round subwoofers and we get some really good results with them!

Also, the Gladen Zero Pro 12 we used, you are right the box is very shallow and we had to space the subwoofer out to clear the back of the box, it was designed like that for the LED's and perspex etc. Might be tempted to sell the setup in the Golf if you were interested
 

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Discussion Starter · #10 ·
Budget of around £500 all in. will check out those subs though. As a general rule (i know this will vary from speaker to speaker) but 2x10 subs v 1x12 sub, for the purpose of metal would the 10s be a better suit? quick fast double bass pedal for example?

Depends on the price


Had lined up the Hertz and DLS as they were 2nd hand very good prices for the quality i had researched.
 

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TBH, more than the speaker itself, it will be the box which will dictate how fast the sub responds. My 18's play VERY fast and can play dance/techno with no issues, again, I have an 8inch subwoofer in the workshop which plays down to 25hz no issue...its the box thats actually making the subwoofer play how you want it.

Pricewise for the Gladen Zero Pro 12 with the box I have it in will be £350 (I would charge £225 just to build the box alone) plus the cost of an amp

If £500 is the budget, then I would say either 2 Gladen Audio SQX 10s with a Mosconi ONE 240.2 or again, if thats pushing the budget, then 2 Gladen Audio RS10s off the same amp or a Mosconi ONE 120.2. You have to remember this is new equipment so it may appear your getting less power than going second hand, BUT its all new with warranty and IMO will do the perfect job of what your after.

You could always buy the Zero Pro 12 and use the A6 to power it
 

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Discussion Starter · #12 ·
Is the zero pro sealed or ported? Was going to build sealed boxes for each hertz sub exactly to their 'performance' capacity rating to maximise their performance. maybe new would be better then, i just thought i'd get more for my money 2nd hand
 

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Its sealed as well mate, didnt want massive bass and retain max SQ. The sub has won the EISA award for best subwoofer and I can really see why!

You dont need to remove or do anything, the box is a straight fit. The spacing of the subwoofer was done on the mounting part of the subwoofer box (where the LEDs are located)

Some better pics





In the same sized box, we have heard the SQX's retain as much punch as the HX's but gain on the bottom end response with no factors changed
 

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Fair play was hoping for a tight snug fit (side to side) so hoping dimensions are near enough the same. Can i ask why you went for 34l? i am very tempted as it's a good sub, minimises boot space intrusion and already has illumination (i was going to include in my build).

Can i ask is the Gladen SVC or DVC? looking at both the Zero pro and the SQX
 

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Yeah this box I built to fit snug between the arches, there is maybe 5-10mm gap from memory which I left to help position the box in the car etc

I never go with suggested box spec's, I use my knowledge and speaker design/installation experience to design the box to make it sound how I like it. How does a manufacturer know how I like my bass
They are a good starting point however for an all round sound.

The reason I went for 34ish is because I wanted to lift the bottom end response slightly for the my music taste yet remain punchy enough for what my wife listens to daily.
 

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Discussion Starter · #20 ·
Ah nice ok, give me room to secure too and run wires. If you don't mind me asking what music do you both listen to? Either of you metal heads by any chance?

Makes sense would really satisy my occasional low end needs then whilst keeping the double bass tight and precise.

Where are you based?
 
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