Tuning your Sub Amp - Tell me how it's Supposed to be Done...

[Danny818]

I have a RF 500a2 bridged to my MM120, and I consulted with the Rockford guy who said that in order to get the most out of my amp, I have to match the gains with the outputs of my head unit. That means that I have to turn my gains all the way down, which means no more hard thumping unless I blow my ears out with the interiors.

What do you guys recommend? How do you have your systems tuned to acheive perfection? Do you make adjustments on your head unit rather than on your amps? Fill me in. Thanks in advance!

[Mtxmann]

First off if you want the best sound from your amp you either want a Headunit with High Voltage outputs or a booster for the signal... boosters seem to be getting more and more uncommon... If you're looking for a high voltage output on your deck i suggest Alpine or Panasonic... I think the cheapest model of each is around 350 with the alpine at a 4v output and the Panasonic at a 5v output... I know that you can pick up either (or just take a look) at your nearest circuit city (ps the panasonic also has an OEL display, i've seen the knobs break on them though...) Also to adjust your amp start with the gain low and slowly increase it untill you hear distortion from your sub, then turn it down untill you no longer hear distortion (this should be done with your deck at the volume level you normally have it at)


hope this helps :D

[Danny818]

Actually, I have a Pioneer DEH-P9200R head unit which has 4.8V pre-outs, which is more than sufficient for my 500a2 which only takes up to 4V. The problem is that with the gains turned down, I don't get the same thump that I used to get. I was wondering what people do on their head units to compensate? I guess just turn up the bass. Thanks.

[Mtxmann]

You realy don't need to have your gain cranked down just keep it low enough to keep your speaker from distorting... Distortion is a key way to tell if you're pushing the sub too hard... thereby risking blowing your sub... personally i think rockford is a bunch of idiots and that's why he told you to keep the gain down(not bashing your choice of amps just the company in general ;D)

[sntnsupermen131]

i tune my amp by what mtxman said
turn your gain all the way down...turn your radio all the way up...turn the gain up to you hear distortion....turn the gain down just a little...and youre set
that is a nice amp...but why did you buy a 2 channel rather than a mono? woulda been cheaper
-Cody

[Jstas]

The voltage of your pre-amp outputs is not important. Well, it is but it is not bad if you have a 1.2 or a 2.0 or a 1.6 volt output. That just means that you have to turn up the gain to get sufficient volume from the speaker.

What the Rockford guy was talking about is that you should find out what voltage your pre-amp processor is putting out to your signal cables and set the gain on the amp to match that signal. This is done to ensure optimum sound quality which is what I think every manufacturer strives for. However, if you want volume, you need to turn up the gain. But musically, turning the gain up too high does not work well for music. But you want boom boom so turn it.

Just forget "boosters" completely. They are a waste of time and introduce noise into the system. They aren't worth the time. All they simply do is increase a weak signal's voltage. They increase the amplitude of the signal and that cause holes in the frequency waves and totally screws up the curve because then you are relying on a digital source to fill in the errors of an analog signal and the signal ends up getting clipped. Clipped signals cause noise which, when amplified and played through speakers, manifests itself in distortion. Stay away from boosters. They are a cheesey Pep Boys audio "patch" to help a lacking head unit perform to levels higher than what was designed into it.

To adjust your gain, the process mentioned above does not allow for any head room. If you adjust your gain to the point where you hear distortion and back it off a tad, you leave youself no room above your normal listening point and consequently, running right on the edge. Some songs and recordings have strong signal strength and will cause you to have to constantly adjust volume, treble, bass and other equalizer settings to compensate. That will constantly throw your system out of whack and it ends up never really sounding exactly how you want it. How I normally adjust gain is to set it to the pre-amp voltage level to match. Then, you can usually go a bit higher with no ill effects. But, if you want boom-boom, you will need to push it higher. In that case, I rarely go with any more than half the voltage. Since the gain drops as voltage goes up, it's backwards. If I have 4V pre-amp outputs, I turn the gain up to the 2.0v point. The reason for this is signals are dirty, especially in cars. The stronger the signal, the less information gets dropped between the head unit and the amplifier. But, that still doesn't mean that there aren't any errors. So turning up the gain also amplifies errors and the amplifer's error correction software can only compensate for so much before it's physical limits are stretched. If you follow that advice for adjusting gain, you shouldn't run into problems. If it is not loud enough for you after that then you need more power.

Distortion is not a "key way" to tell if you are pushing your sub too hard. Distortion is evidence of a dirty signal, exceeding the limits of the amplifier's capabilities, a bad ground, insufficient power, poor signal source integrity, RF or EM intereference and just plain old simple signal degredation. If you are pushing your sub too hard, it will manifest itself in distortion but it is usually extreme distortion which makes more than just a crackiling noise. It makes popping and cracking sound like the sub is physically ripping itself apart. Which it is. Average distortion results from signal break down caused by the reasons I mentioned above. It is by no means a "key way" to tell that you are pushing your sub too hard. You are not running enough power through that sub to be pushing it too hard.

As far as Rockford Fosgate's staff being a bunch of idiots, well, so says you. Personally, I would recommend Rockford Fosgate equipment over anything in Panasonic's line up. They should stick to making electric razors. And Alpine is nice but I'd still prefer Rockford Fosgate stuff over Alpine. I also highly doubt that RF is a "bunch of idiots" being as they have been in the business for over 20 years and have beaten everyone at the game. They may not have the sound I like but they are far from idiots.

As far as prices go, Aiwa, Blaupunkt, Alpine, Rockford Fosgate, Kenwood, Pioneer, Clarion, hell, even Sony all have head units with pre-amp output levels higher than 2 volts for less than 350 bucks. In addition, there are wholesaler sites that have 600 and 500 dollar head units for prices that are 30-50% less than retail. There is no reason anyone has to subject themselves to the horror that is Panasonic just to get 4V pre-amps at a 350 dollar retail price.


Now, as far as what I do, well, I already mentioned it. I'm running a Kenwood eXcelon KRC-PS955 head unit with an eXcelon X-650D 5 channel amp. I have my gains set just a smidge above the 4V setting for my pre-amp outputs. I can push them higher but I don't like how the signal breaks down and truthfully, it's loud enough for me right where it is. It's crystal clear and that is what I am looking for. I don't care if I can shake the kid's car next me. I just want as clean and clear and detailed a sound as I can get.

[PoweredByDodge]

just a little tidbit of note here...

voltage tolerance on amps is rated as an rms scale... "0.250 to 4.000 volts" on the gain...


voltage on your head unit is rated at a max scale, and its not always before clipping ... alpine's dual 4 volt preouts are actually 2.5-ish volts..... before clipping probably 2.

i imagine pioneer's 4.8 is probaly high 2's, low 3's... before clipping... probably 2.5 or so.

4 - 0.25 = 3.75

3.75 - 2.5 = 1.25

1.25 / 3.75 = 1/3

throw your gain at 1/3 to start and tweak it up or down from there -- bet ya money that's where she hits the clip/not clip range if the deck is just inside its own clip point (ie "top" volume that you'd listen to it at).

[mtxmann]

Jstas...

Just for clarification...

When i was talking about pioneer, alpine, and panasonic i was refering solely to Headunits (i would still take an alpine 4ch amp over a fosgate) I was simply throwing out some suggestions of headunits that have higher than standard voltage outputs at a reasonable price that he could pick up at a local retailer.

A question...

What sony headunit has more than a standard 2v output... the first one i've seen is this years model with the TFT display which has 4v... Last year i spoke with a Sony rep about that years model with the TFT display (the dry deck) in regards to it's output and he told me that every sony that year has a 2v output... I you can tell me a model number please do i'd love to be proven wrong in my general Hatred of sony car audio.

In my humble opinion...

From what I have seen MTX has surpassed RF in the last couple years... They have beaten RF in competition and in development with more new and inovative product (the new 9500's should prove this yet again) feel free to give me hard technical data that proves that RF is better than MTX (recent not 5 years old) and I'll change my opinion. I have no problem with being proven wrong, it's the only way we can learn anything...

Lastly...

Keep in mind that i was offering basic info to someone who seemed to have basic knowledge... I know that distortion doesn't prove that the sub is being pushed too hard i simply worded my statement wrong... Had i put more thought into it at the time i would have said something along these lines " Distortion shows that your gain is to high for the setup you have" wether this ment his cables, HU, amp, or subs were the problem the point that i was making is that Distortion is a sign that something is wrong...

[Danny818]

Thanks for all the input guys. Cody, I bought the 2 channel amp at the time because I saw a better deal for it than mono amp.

I didn't mean to spur such a controversial topic. I guess to each his own. I guess the only way to accurately measure your head unit's output is to hook it up to an oscilloscope, but who the hell has one of those lying around the house?

Before, when I had my gains on my 600a4 amp for my interiors turned about 1/3 up, I had a little alternator noise. Now that I have it all the way down, I don't hear it anymore, so that's a great thing. I still have to tweak with the settings some more. Thanks again guys.

[Jstas]

I'm not going to argue nor do I care to waste time searching the internet for the proof you desire. A simple flick through teh Crutchfield catalog will yeild more examples than you think.

My post was not meant to anger you. You gave incomplete and on some points, inaccurate information. I felt that it needed to be corrected before the guy went and blew up his expensive speakers.

As far as Sony goes, I dislike Sony for anything but TV's and VCR's and maybe the Playstations. The Sony head unit I looked at online may have been last year's model but you can still get them for less than 350.

About MTX and your opinion. I will not enter any debate with you regarding your opinion. Your opinion is your opinion and I won't change it. But, just because I neglected to mention MTX doesn't mean I wouldn't recommend it. My comments about Rockford Fosgate were in relation to your comments about the inteligenece level and competency of Rockford Fosgate employees. Not once did I ever mention MTX. Why you are bringing it up now, I do not know.

[sntnsupermen131]

doesnt rockford hold the spl world record?
and their new line of amps the type(insert number here) and supposed to be the cleanest amps theyve ever made
and they look sweet too!
-Cody

[PoweredByDodge]

i wont speak on year 2k3 gear, but RF has consistently mfg'd product that is of better sound quality than mtx.

mtx has consistently put out amps that will keep playing even while they're on fire -- and for that, they get the "durable" award.

i dont believe u can drop an impedance load on an RF and see it live -- u can do it on an mtx.

i dont believe u get any respectable SQ out of an mtx amp post-Blue Thunder Pro, while RF has proven they can make loud beautiful power (in comparison to similarly classed stuff -- we're not talking Brax here folks).

the 9500 subs will be jack **** next to the Power HX2 line.

PHX2 15 makes the 9500 look like a midbass driver.

RF makes junk product so does MTX... RF Z / Punch HE is crap just like MTX 4000 / old 5000 is.

RF makes a mid grade sub like a Punch HE2 ... mtx makes a 6 and 8 k...

finally mtx has stepped into the power class with the 9500 but i think they should have stuck to amps -- they're spreading themselves thin, and its easy to see... quality of prodct in general is goin down the ****ter ... and from what everyone is sayin about new RF being at spec instead of way above spec leads one to believe the same thing for them.

after having bought a **** load of mtx gear... and ripping apart cody's RF as well as listening to a lot of RF, i can say one thing...

if i had to buy all new amps tomorrow.. i'd buy mtx... but not for the reasons u think...

1- price, mtx is cheaper.
2- tech support.... RF techies suck hardcore, dont know their butt from a hole in the ground, and u cant talk to a true technician if u'r elife depended on it -- u get "cust svc reps" who look at an amp as a black box with ins and outs and thats it.
3- price of repair -- mitek will evaluate an amp for 40 dollars and most repairs are under 100.... RF has a 280 dollar flat rate.
4- privately owned vs publicly traded -- privately owned companies tend to "give a ****" more.

however... if i had more money, didn't care about techies.... I'd buy RF...

1- better sound quality
2- better looks
3- more power options to better suit system needs.
4- lower distortion, higher slew rates.
5- size, a bd1000.1 is without shrouds physically the same size as my girl's mtx 302. could use some ventalation, but a small footprint is helpful.

mtx has been gearing toward the spl lanes more than u'd think lately... less andl ess emphasis is being placed on the quality of sound of the "daily driver" amps... while power output on the sub amps as well as circuitry to allow "strapping" of amps without an external module has been the big thing this year.

and for the record ---- i'd buy an RF power series for my highs long before i'd buy an alpine .... at least my speakers will be loud enough to hear on the RF.