I am looking to upgrade from my Phoenix Gold amps and am wondering what makes a good SQ amp? I know Audison, TRU, PG, ARC and others are all good brands and have a great reputation but what do you look for when buying an SQ amp?

With speakers you can listen to others cars, listen in stores and certain types of speakers have certain charastics i.e. dome mid Vs cone mid etc...

I thought of auditioning them but dont see all the models i'd like to trial on display boards anywhere and even when they are they are driving speakers completely different to what i'm likely to be running them on so the sound is different anyway.

A lot of specs are quoted as being important so what specs and other build features are important?

Signal to noise obvously affects your noise floor
Distortion at which power figures are claimed
Actual rms output (most reputable brands meet and excceed there claimed output)
Dampening factor

Obviously things like fans, crossovers and protection are all extra's so what else is there to consider?

I can either go fully active requiring 6 or 8 channels of amplification + sub amp (3 way front stage + rears + sub amp)

Something like 1000rms at 2ohm for sub
4 x 50rms tweeter & rear's
2 x 100rms midrange
2 x 200rms midbass

or Pasive

1 x 1000rms at 2ohm for sub
2 x 300rms to front stage
2 x 20-50rms to rear

What do people know about Earthquake amps? Their BASS or Powerhouse series? They are great value with good specs but i dont hear much about them?

what i look for is something that had exelent build quality, is flexible to run anything i want and looks good. the only problem is to get all that and not be broke at the end of the day i had to buy secondhand.
i use a SS ref 404s for my front stage. 4 x 50wrms (underrated) and can be loaded down to 0.5ohm, idependent gains on each channel etc etc and looks very nice build quality would be one of the best i have laid my eyes on.
it's something that i brought knowing i would want to keep it for 10+ years.

Thanks, i am certainly happy to go second hand but want the system to be matched so that will mean multiple amps fromth e same series.
some specs on the earthquake amps i am considering are outlined below and they are supposed to be very conservatively rated.

PH2200W.4

Number of channels: 4
RMS Power 2-Ohm Stereo: 4x350
RMS Power 4-ohm stereo: 4x175
Damping Factor: >800
Cross over slopes: 24dB/OCT
THD: >0.016
SNR: 104dB
Class: A/B
Speaker Connection: 12-Gauge
Power Connection: 4-Gauge
Input Type: Independent Low Level RCA
Dimension: 2 1/2" x 10 1/2" x 13 3/8"

PH2000W.2

Number of channels: 2
RMS Power 4-Ohm Bridged: 1x750
RMS Power 2-Ohm Stereo: 2x375
RMS Power 4-ohm stereo: 2x300
Damping Factor: >800
Cross over slopes: 24dB/OCT
THD: >0.016
SNR: 104dB
Class: A/B
Speaker Connection: 12-Gauge
Power Connection: 4-Gauge
Input Type: Independent Low Level RCA
Dimension: 2 1/2" x 10 3/8" x 13 1/4"

unfortunately there's not many specifications to determine the differences between amplifiers.
IMO steer away from class D for a pure sq application, although they do have benefits if you're willing to sacrifice a little SQ.
did you ever compare your 200mkII to a class a/b?

Yes but not back to back in the same car with all other things being equal so it is hard to guage the difference .
I will be selling it though and going class A/B this time, the question is just how many amps and which ones.

I currently have 4 so looking to go 2 or 3 max.

If i go pasive front stage with something like the dyn 3 ways (which i have just installed into my wifes car and am very happy with) it's eaiser to hook up, only need one good 2 channel amp, but i can't use the time allignment from the headunit.

If i go fully active then can use time allignment but need more amp channels and it is mroe complicated to hook up.

Hi slew rate is something that is important for high frequency response.

Also look at how flat the response is in the operating range of the amp.

Frequency response that extends past the human ear's capability of hearing can still be important as it affects the harmonics created. (As CD bandwidth is limited sometimes a spatial restoration device is required to help achieve this)

There are so so many things to considder.

Having said that most people (practically everyone on the plannet) couldn't hear the difference between amps unless they have some sort of equalisation or x-over affect that has been set by the user.

So your saying that MOST people couldn't hear the difference between a Boss 1000 Watt amp, and a Sound Stream Davinchi amp??

Hmmmmm BOSS amps, nice and shiny....... and rated to produce 1000watts,

slew rate isn't terribly important, i haven't seen an amp that has a slew rate which would affect <40Khz frequencies.
bandwidth up to 40Khz is nice, there is a small amount of information there which can help tighten imaging and help with ambience.

i have heard alot of differences between amps, regardless of whether it was a crossover, or different frequency response or something else, i've also noticed better imaging with high quality amps.

Just as Bobby Digital said...buy on power, build quality, back up service etc...and perhaps on reputation as products get a good/bad reputation for a reason...perhaps look to here and overseas SQ results and see what people are using

That being said I agree with HISPL...many people cannot pick minute differences that may exist between amplifiers...and even a/b ing them in a store won't tell you much as I don't know of any stores with demo boards that support multiple amlifiers who set all gains with a scope to be exactly the same...with this being the case any perceived SQ differences in a demo board environment are often the result of one amp being louder/quieter than the other or crossovers set differently/turned on etc...

Specs too are only a guide...you can drive a car with great specs and it sucks to drive but the numbers look good on paper...you can also drive one where the specs are not as good but it's a blast to drive....and as we all know some car audio manufacturers are a little shall we say optimistic when it comes to the truth in their specs...although most major name brands are pretty good in that regard.

Good luck choosing your next amps...

Yes, depends on conditions tho.

If the amps are both run while the vehicle is not running (so there cant be noise problems associated with alt whine, ignition tick etc etc) I think it would be difficult for most people to be able to tell the difference so long as both the amps are not clipping.

Base on my experience, those spec can only be use as a guideline only. In real life it is totelly different story. So listen and your experience will tell you where to go. Something look identical on the paper may totally sounded different. There are some parameters that could hardly evaluate using simple labs equipment but your wars can hear it. Something like comparing tubes amp and mosfet amp. So keep listening is the key.

I can think of two off of the top of my head that have a low slew rate where the SQ is affected by it. (I'm mainly going on what Eric Holdaway says, hopefully you respect his opinion to the same degree as I do)

But surely you dont think that you can hear up to 40khz, it is the harmonics that these frequencies are effecting.

i think the spec's on the SS lil wonder sum'd it up perfectly

Considering they're both about the same quality, why not?

Yes i know how different tube amps sound, although i'm not looking at going that way.

there may be some isolated cases, but in general slew rate won't affect the amp's output, generally it's a measurement used for higher frequency amplifiers (data comms) where they talk about 40 megahertz!

i know i can't "hear" beyond 20K, i actually had my hearing tested and my limit was 18K, which is apparently pretty high for a real world test.
i believe that frequncies above our listenable frequency scope can still offer benefits to sound. i believe we can still sense them, and it can help to sharpen imaging.

You want Sound quality, how about a Soundstream Human Reign . Or if you want something cheaper a class A/B Tarantula amp .

Oh and the Little Wonders are back this year .

Next year we are bringing back the Rubicons. All still made in the old factory in California. So for people who knew Rubicon we will cater for the old school market.

Human reign looked good as far as specs go. What about pricing on them?

The Human reign is very expensive $7999.

Your've got to be kidding? Is that for them to build it in my favourite colour and install it along with the rest of my system by a team of soundstream installers or the supply only price? LOL

I could get the second hand Davinci for $4k and that would be my dream amp.

Obviously, something is only worth what people are willing to pay for it!

I don't think that $7999 is expensive, in is just at the higher end of the price spectrum where there is only a small quantity sold to the few that can justify the expense.

Some people may view it as a good VFM alternative as an SQ amp compared to a Milbert tube amp or a Tru Tech "Class A" however the owners of these amps may think that their is really no alternative to the amp that they have.

At this end of the price spectrum a choice on amplifier tends to be a lot more emotive than at the other end of the price spectrum, where people probably could care less if their amp has BOSS stamped on it or "Black & Gold"

I love Rubicon, have had them for 5 years and still going strong.

Sorry didn';t mean it that way, it's just more expensive than i am prepared to pay, i'm sure it has its selling points, but unfortunately my budget wont streach that far.

At the level your looking at buying, i believe a good car audio store should be able to set up a demo with certain amps. As long as they stock the product theyres no reason why you couldnt ask them to hoook up a set of Dyn 3ways, with a audison, PG and Tru tech amp for example, and have a back to back test with the amps. Even if you let them know a day or two before so they can set it up. Most reputable home audio stores do this and i believe good car auido stores should to. Even if its not in your car and the same environment as you will be listening, it will still give a level playing field for you to listen to the components.

Thanks i'll considder that. I guess if you never ask you'll never know how far a shop will go to assist.