Is my amp gain set properly? Speakers bottoming out...

[Arythael 10+ year member]

Edit: All I'm trying to get from this thread is an explanation as to why my max volume dropped from 28 (with a test tone) to 23 (with music) like it did. I'd like to know how to set my gain and HPF so that my max volume is 28 on music before my speakers start bottoming out, and hopefully they would be able to reach higher volume levels than they can now. My apologies in advance for the long post, but I'd prefer to give too much information rather than too little... so here goes:

So I'm doing my first install: CDT CL-61 6.5" components for my front stage powered by an MB Quart ONX4.80 amp, with a Kenwood KDC-HD548U head unit. The speakers are rated at 160W rms (@ 120 Hz high-pass filter), so I'm using the bridged outputs on the amp (which can push 320W x 2 @ 4 Ohm, rated). I followed jmac's amplifier setting tutorial, which went something like this:

1. Speaker RMS power = 160 watts; speaker resistance = 3.9 ohms (tested with DMM)

2. Calculated from V = sqrt(P*R), my amp output voltage should be sqrt(160*3.9) = 24.98 volts

3. Disconnected speakers from output of amp, stuck multimeter leads in each of 2 channels (one channel at a time).

4. With DMM set to AC voltage, I played a 1000 Hz (0 dB, I believe) test tune with head unit volume knob at 28 (real max volume is 35, starts to audibly distort around 29 so I used 28 as my max volume).

5. Turned up gain on each channel to a DMM-measured 24.7 volts (as close as I could get to 24.98v without going over).

6. Reconnected speakers to output terminals on amp, switched amp from full range to HPF mode, turned HPF knob to its highest frequency.

7. While playing a 125 Hz test tone (still 0 dB as far as I know) with volume still set to 28, turned down HPF until I noticed audible distortion, then turned it back up a little bit more for safety.

For the most part, this seems to have worked out great. Considering the huge improvements in sound quality and volume over the stock speakers, I'm mostly pleased with the products (for a low-budget system, that is). My main concern is that they don't get loud enough: they get decently loud, but once I buy and install my substage (planning on 2 12s, 1000-1500W amp, ported), there's no way these speakers will be able to keep up, so I want to make sure I can get them as loud as possible.

Anyway, I'm experiencing two major problems:

First off, my speakers bottom out -- at least I think that's what's happening, the speakers make a very loud tapping/knocking noise -- at medium-high volumes, usually around 23-24 on my head unit. From my understanding, music does not often play at 0 dB and thus should not even begin to bottom out until a minimum volume of 28 on my head unit.

Secondly, and more strangely, I have noticed that bass still plays through the speakers even with the HPF on... songs that play certain low frequencies sound altogether horribly distorted (so much that vocals can barely be heard/understood). I noticed this most prominently while playing A Milli.

More miscellaneous info: the speakers did not bottom out during 125 Hz tone @ 28 volume, even in full range mode; I used the same source (my iPhone) for the test tones and the music; iPhone volume all the way up in either case; iPhone and head unit equalizer both flat/off; Bass boost on head unit and amplifier both off/0dB.

So, did I do something wrong? Am I missing something, or are my speakers just having trouble doing rated? Is my amplifier's high-pass filter not working properly, or did I set it wrong? Please help!

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[blazeplacid 10+ year member]

I have never used a formula to calculate gain setting.

I listen to my ears instead of calculated numbers. I dont even use test tones.

Find a song you like.

Set the volume on the head unit up to 3/4 or 7/8 man volume.

Let the song play and slowly turn your gain up.

The crossover isnt an exact science either. It will not cut off exactly at 80hz. It will roll off around that range.

My point is mess with the gain and crossover settings until your ears are happy.

Ive been doing it this way for 10 years on my set ups and countless others.

 

[VisceralSound 10+ year member]

So your midranges are set to Full, and your tweeters are set to Highpass correct?

 

[Arythael 10+ year member]

I have never used a formula to calculate gain setting.
I listen to my ears instead of calculated numbers. I dont even use test tones.

Find a song you like.

Set the volume on the head unit up to 3/4 or 7/8 man volume.

Let the song play and slowly turn your gain up.

The crossover isnt an exact science either. It will not cut off exactly at 80hz. It will roll off around that range.

My point is mess with the gain and crossover settings until your ears are happy.

Ive been doing it this way for 10 years on my set ups and countless others.

I've just recently begun looking into the car audio scene, and this is my first install. I wouldn't mind doing this once I'm more experienced, but I'm afraid I might damage something this way. Hearing the speakers bottom out is scary enough in the first place... I'm a broke 19-yr old college student, I can't afford to **** up a system I just paid $400 for

So your midranges are set to Full, and your tweeters are set to Highpass correct?

The CDT CL-61 is a component set with passive crossovers... my amp runs to the CDT crossovers, CDT crossovers go to woofers and tweeters. The amp is the only thing with a variable HPF, and its currently on HPF mode set to somewhere around 140 Hz (as best as I can tell; there are no numbers around the knob besides min/max values).

 

[Flex68 10+ year member]

Didn't read all , but not sure why you set up ur amp on "Full range" and then went to "HPF" with the setting at 140.

If you're running a passive system, why not keep ur amp as you sat it up, and let the xovers do the filtering...?

 

[Arythael 10+ year member]

Didn't read all , but not sure why you set up ur amp on "Full range" and then went to "HPF" with the setting at 140.If you're running a passive system, why not keep ur amp as you sat it up, and let the xovers do the filtering...?

It was never used on full range except during setup and testing. I'm using the HPF on the amp for the same reason component sets use a crossover to feed the woofers and tweeters different frequency ranges: because the woofers shouldn't be playing frequencies intended for subwoofers. In full range mode, these woofers bottom out at even lower volumes, and lack of loudness is already one of the reasons I made this thread. Also, the sound from them seems to become increasingly distorted at increasingly lower frequencies. I saw several speaker amp gain setting tutorials mention using a HPF when I was originally searching; I didn't realize this was such a strange thing to do? The logic behind it seems sound enough to me //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

Edit: All I'm trying to get from this thread is an explanation as to why my max volume dropped from 28 (with a test tone) to 23 (with music) like it did. Unless the test tones weren't truly 0 dB tones, I don't understand how this could happen? I'd like to know how to set my gain and HPF so that my max volume is 28 on music before my speakers start bottoming out, and hopefully they would be able to reach higher volume levels than they can now. I'm not primarily asking for a way to set it up, I want to know WHY you would set it up that way. Preferably with some form of calculated method, not just "do it by ear". What's the use of knowledge without understanding behind it?

 

[trumpet 5,000+ posts]

You need to have speakers connected while you set the gains. This is why they're sounding horrible. Redo the gain procedure and don't use a 0 dB tone. Use -5 or even more attenuated. 0 dB test tones make it so you're wasting power and never getting to maximum loudness.

 

[Arythael 10+ year member]

You need to have speakers connected while you set the gains. This is why they're sounding horrible. Redo the gain procedure and don't use a 0 dB tone. Use -5 or even more attenuated. 0 dB test tones make it so you're wasting power and never getting to maximum loudness.

I may be a newbie, but I'm fairly certain that this is just not true. Every single gain setting guide I have come across specifically says to disconnect the speakers, but I attempted your suggestion anyway and got the result I expected: the exact same result as when the amp was set up with the speakers disconnected (although, I found it strange that the speakers would not create any sound while the DMM was inline with them, even though voltage measured the same as when the speakers were disconnected). Someone please correct me if I'm wrong, but... voltage is directly controlled by the gain knob, and voltage is what I'm measuring in this case. The amp is going to output the same voltage regardless of what is connected to the amp output terminals.

After writing the above paragraph, I realized that there's a chance the resistance I used in my V=sqrt(P*R) formula is not correct for setting my gain: I used 3.9 ohms, which I believe was measured directly from the woofer terminals, while I think I should actually have measured the resistance of the speaker wires that connect to my amp (the entire woofer+tweeter+crossover circuit). I know I checked the tweeters before and they measured 3.3 ohms, but I don't remember if I ever checked the entire circuit. It's raining now, I will check this tomorrow and post my results!

 

[caewen 10+ year member]

You sure thats 160 Watts RMS per speaker? And not shared between the set. I.E. could they actually be 80 Watts each? I looked at several sites from Google search, one said 130 another said 150 another 160 and the CDY site says 160 Watts RMS at 120 Hz.

 

[Arythael 10+ year member]

You sure thats 160 Watts RMS per speaker? And not shared between the set. I.E. could they actually be 80 Watts each? I looked at several sites from Google search, one said 130 another said 150 another 160 and the CDY site says 160 Watts RMS at 120 Hz.

Hahahaha... simplest answers are usually the best. I would assume any rated power specifications would be for each driver individually, but it looks like you sir are correct.

This is the woofer from my component set. After some quick searching, I found CDT's official technical data on it:

http://www.cdtaudio.com/pdf/CL-6E.pdf

Power Handling: 80 Wrms (100 W pk)

I'll need to look into this more... tomorrow I will try to determine the power they're getting when they begin to bottom out; I wouldn't be surprised if its around 100 W.

 

[caewen 10+ year member]

Cool deal man, stupid company marketing **** is stupid.

 

[trumpet 5,000+ posts]

CDT Audio power ratings are per side on component sets. The pdf is for the midrange drivers only, which is one reason the power rating is different. There may be different power ratings published because of different versions of the CL-61 set. Are these the old red basket mids? It would be the set shown here: CDT CL-61 Component Set+Upstage kit.

If it is the same as that set shown in the link then it's 160W peak, 80W RMS for the mids only. 160W per side accounts for the tweeters as well. Either way, this is splitting hairs. If you really listened to your music at 160W that's well past the threshold for pain. Ultimately we have to listen to the speakers and trust our ears, not a meter.

 

[Arythael 10+ year member]

I attempted to measure the power that they were bottoming out at, and it seemed to be about 57 W... which seems way too low, so I started to think that the DMM is junk or I did something wrong. When I stuck the DMM leads into the speaker wires that connect to my amp (and run to the crossover+tweeter+woofer circuit), my DMM measured a constantly changing resistance of 3.7-4.2 ohms... even more reason to believe the DMM is junk. It is an Ideal Resi-Pro 61-310 Multimeter, and it was just bought new a few weeks ago. Anyway, I still tried to redo my gains for 80 W rather than 160 W.

Using 28 as my max head unit volume, I set up my amp with a target voltage of 17.8 volts for a target power of 80 W. I still used a 0 dB tone; I understand the argument towards attenuated test tones but until I can figure out what I'm doing wrong, they would just make my problems worse. Back on topic, it worked out much better than before, but the speakers would still bottom out before I could reach max volume (around 25-26 now, up from about 23-24). I'm so frustrated with this ridiculously simple problem that I ended up just turning my gain down in very small increments until I could reach 27-28, I'm not sure what voltage/power it is at anymore.

[quote name='trumpet']CDT Audio power ratings are per side on component sets. The pdf is for the midrange drivers only, which is one reason the power rating is different. There may be different power ratings published because of different versions of the CL-61 set. Are these the old red basket mids? It would be the set shown here: CDT CL-61 Component Set+Upstage kit.

If it is the same as that set shown in the link then it's 160W peak, 80W RMS for the mids only. 160W per side accounts for the tweeters as well. Either way, this is splitting hairs. If you really listened to your music at 160W that's well past the threshold for pain. Ultimately we have to listen to the speakers and trust our ears, not a meter.[/QUOTE]

Nope, they are not the red basket model; my woofers, tweeters, and crossovers are all different than the ones shown in that post.

I bought this component set from @mylows10 (maybe he has some input for this thread?), and these are the specs that he gave me:

CL 61 6.5î 2-way component system
Technical specs and contents:
1 pr CL-6E 6.5î mid-woofer
1 pr TW-25 1î silk tweeter
1 pr EX-530 24dB 4th/5th order 2-way crossover
Power handling: 160 watt RMS @ high-pass 120Hz.
Frequency response: 60Hz-20.000Hz
Impedance: 4 Ohm
Sensitivity:90.8dB
Mounting depth 6.5î woofer 2.5î
Flush and surface tweeter housings

 

[mylows10 5,000+ posts]

these are the specs from cdt if the components are not handling the power that you are putting on them ,then maybe the the x over is set too low.but is they are bottoming out at low wattage then there may be an issue with them .they are still under warranty ,you can send them back to have them checked out ,but you'll need to pay shipping to get them there. if they find nothing wrong with them then you'll have to pay to have them shipped back too.sounds like too much bass is being introduced to the mids to me tho.