THD with track 7?

[MrSkippyJ]

THD will be the same since the light turns on at 1%...it ONLY matters which attenuated tone you use. the ONLY difference between the tones is what volume they're recorded at. thats it.

Yeah, but if you use the -15dB track to set your gain at 1% then play music that is recorded at -5 or 0dB the THD will go up correct? My question is, how much will it go up by switching?

And MrSkippy the DD-1's not going to keep me from overpowering the subs, just give me a rough idea how much I'm overpowering them by telling me about how much over the <1% THD Jake used when he rated my amps that I really am.

I hope that helps. I confused myself a little there. lol

You need to worry about clipping the signal before even considering how much THD you have. If your main concern is overpowering your subs then I would stay far away from using -15db to set your gains. That setting gives you the least amount of forgiveness of any of the settings.

Edited March 28, 2012 by MrSkippyJ

[Blue_C1500]

You need to worry about clipping the signal before even considering how much THD you have. If your main concern is overpowering your subs then I would stay far away from using -15db to set your gains. That setting gives you the least amount of forgiveness of any of the settings.

I'll take that as an "I don't know"...

[Decaf]

Every amp is different and is rated at different THDs because of components used and so on. There is not a definitive answer as to how much %THD is produced by each tone without measuring. %THD is the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency.

Simply choose a tone closest to the loudness of the music you play most. All rap is -15dB in loudness or louder, so -10dB would be a wiser choice to use. Personally I use -5dB for even more safety and because I play very loud music.

[MrSkippyJ]

You need to worry about clipping the signal before even considering how much THD you have. If your main concern is overpowering your subs then I would stay far away from using -15db to set your gains. That setting gives you the least amount of forgiveness of any of the settings.

I'll take that as an "I don't know"...

Correct, I have no idea what the THD is of your amp, the only way to know is to measure. Even the rating given on the box isn't exact which is why they usually say THD is <1% (or whatever number). I'm still a bit confused why you are so worried about the THD of your amp though.

[Blue_C1500]

Like I said, I'm not worried about anything. I'm just curious. I think you are reading to much into the question. I pretty much only play my subs at competitions & I feel that I need to use track 7 to set my gains because it is going to give me the best #s on the meter. What I plan to do is use track 7 to set the gains with the sub level control on the radio all the way up for metering then put in the -5 dB track on and turn down the sub control until the DD-1 says it's clean and use that setting for demos. So basically, I'll only be burping with the -15dB setting and any music I'd be playing would be with the -5dB setting.

Decaf, I understand that every amp will be different that's why I was asking an "about" percentage. I just didn't see where anyone had done a similar test on any amp. I pretty much only play the songs that you have modified when I demo because I know they are clean.

[Decaf]

Like I said, I'm not worried about anything. I'm just curious. I think you are reading to much into the question. I pretty much only play my subs at competitions & I feel that I need to use track 7 to set my gains because it is going to give me the best #s on the meter. What I plan to do is use track 7 to set the gains with the sub level control on the radio all the way up for metering then put in the -5 dB track on and turn down the sub control until the DD-1 says it's clean and use that setting for demos. So basically, I'll only be burping with the -15dB setting and any music I'd be playing would be with the -5dB setting.

Decaf, I understand that every amp will be different that's why I was asking an "about" percentage. I just didn't see where anyone had done a similar test on any amp. I pretty much only play the songs that you have modified when I demo because I know they are clean.

You are not getting what I'm saying fully. If you are metering and using 0dB tones you should never set gains with -15dB, you will be clipping HEAVILY. The point of using -15dB is to have gain overlap while listening to MUSIC, no burping tones. Soft clipping can help competitors but heavy clipping usually results in a lower score even if you might have more power.

You have to MEASURE the specific amp to find out how much of the power is the sine wave, and how much power is harmonic distortion... you cannot find that number without the proper instruments to measure all frequencies and their strengths.

If it helps, elow 40hz it takes 20-40% distortion for us to pick it up... above 1000hz and our ears are much more sensitive to distortion.

I

[Blue_C1500]

Ahh... Ok, you don't happen to know if the tones on the USACi disc are 0dB, do you? They won't let you use anything else for the burp classses. I wish there was another organization down here, USACi is so squirrely with their rules.

The reason I was going to use the -15 track is because the manual for the DD-1 says use track 7 for a louder system. I guess I just took that as meaning it would be the best numbers when metering.

[Kranny]

you would always want to use 0db for burping. so then tune your amps for a 0db tone. you're making this more complicated than it has to be.

if you're so worried about fucking shit up, retune everything for whatever you will be doing. -10 for daily, 0 for comps, etc. there is no need why you should use -15 imo.

[Decaf]

Ahh... Ok, you don't happen to know if the tones on the USACi disc are 0dB, do you? They won't let you use anything else for the burp classses. I wish there was another organization down here, USACi is so squirrely with their rules.

The reason I was going to use the -15 track is because the manual for the DD-1 says use track 7 for a louder system. I guess I just took that as meaning it would be the best numbers when metering.

The USACI tones are 0dB

I understand your logic because the wording is vague, but I'm suggesting the safer/proper solution

You would play the -10dB/-5dB track with sub level at max clean setting, then play 0dB and turn the sub level down until its clean also. When burping use the lower sub level, and maybe 1 click higher to see if a little clipping helps.

[Blue_C1500]

you would always want to use 0db for burping. so then tune your amps for a 0db tone. you're making this more complicated than it has to be.

if you're so worried about fucking shit up, retune everything for whatever you will be doing. -10 for daily, 0 for comps, etc. there is no need why you should use -15 imo.

I don't know what I use for burping because I HAVE to use the USACi CD. I know I would want to use 0dB but It's not my choice. The USACi cd could be 0dB or -15dB. I have no idea where they recorded it that's why I asked if Decaf knew...

Again, I'm not worried about "fucking shit up". I beat the crap out of my last set of subs for over 2 years and never had a problem. My new subs use the same coil and have way better cooling so I'm VERY comfortable in saying that they won't let go anytime soon and I'm in a wheelchair so it's not really easy to "retune" everytime I want to do something different. Honestly, it seems kinda dumb to even consider that if all you have to do is change 1 setting on your head unit to accomplish the exact same thing.