Gain Setting & Clipping at Different Frequencies for Front 3-way Active Setup

[richard_crl032]

Hi There,

Doesn't impedence change at different frequencies and if yes, test tone of just 1k means that it is only good for gain matching at around 1k tone for my midrange amp and that I cannot use for detection of clipping for the other 2 amps designated for tweeters crossed at 2.8kHz and above or for the midbass cross below 500Hz ?

I vaguely remembered that with handheld scope, I had seen that an amp may not clipped at some frequencies for gain set but cipped at others i.e. even not usable for midrange amp ????

Not sure how to proceed to use the newly received DD-1 to gain match my Front 3-way setup with 3 2-channel amps ....

Anyone, please help to advise.

Thanks.

Richard@SIngapore

[meade916]

set your bass amps with the 40hz tracks, usually -10db or -5db

set your midrange and tweeter amps using the 1000hz tracks, usually -5db. You are not looking for distortion at "certain frequencies", you are using our reference disc to determine where the deck puts out its maximum, non distorted output, and matching the gains on the amps to that deck. If you read the instructions you will see that you will turn the frequency on the bass amp all the way up when testing (of course, turn it back down after you are finished). Same goes for the amps for the higher frequencies. Put them on full pass so the crossover is taken out of the equation. Then adjust the gains. Once the gains are set, you can put them back to high pass or leave it on full pass and use your external x-overs instead. You sound like you are fully active so thats what you would do anyway.

Please read the instructions fully before getting started. Have fun tuning!

p.s. you got that FAST! (Shipping to Singapore)

[richard_crl032]

Hi Steve,

(1) Thanks for the quick advice and yes, I did get the DD-1 very soon after my order.

(2) I am quite sure I went thru' the manual but it may be due to my poor understanding as this is the first time I am trying to do gain matching outside my installers' shops, hence the idea of getting the DD-1.

I do understand your instructions and comments but the question remains that even at full range with cross over bypassed, the frequency of 1k Hz used somehow does NOT seems complete as I mentioned that:

a) Physic class taught me that impedence which I believe will affect gain matching DOES depends of frequency used .

Gain at 1k was set with no clipping as well as with tones below that from 300, 400, 500kHz etc. from my own CD did not indicate but it did show some clipping at 1.25kHz or something like that which raised my concern if it would not clip at other frequencies although it did not at 1kHz.

3) Also, I do not understand why the manual reference to track# 6 of -15db@ on setting for full range amp for louder system since there is very high chance of clipping if we all agree that typical CD is at -5db and how then we know that it is really clipping the amp.

Thanks again amd looking forware to your continued help.

Richard

6. Play track 4 or 6 on test CD (Track 4 will ensure maximum sound quality, Track 6 will result in a louder system). Your choice.

[meade916]

we put -15 in there just in case someone REALLY needed it for some reason.

i usually recommend -5 on the highs, -10 on the bass and if the bass is still overwhelming, you can always use -5 on that too. It is all part of the "gain overlap". Using a -15db track shouldn't distort your system any faster then using a -5 track if you set the system up properly. All you are doing is shifting the overlaps. The amp is still going to distort when the deck is at full power it will just be screaming loud way before the bass even kicks in (since the overlaps might not be right).

on the other stuff, again, dont confuse yourself trying to over analyze. Its really very basic.

I got a question, what "Physics class" teaches gain matching on car audio amps? I can't answer your question about what is on your CD. Who knows what that is, where you got it, or why you are using it. Even with an o-scope, as long as i have been using one, they have always used 40hz and 1000hz as the two reference points.

good luck! and thanks again!