[Alrojoca]

Happy But Confused About More than DOUBLE the Extra Power for my Mid Bass


I bridged my amp. Now I get nearly 3 times the power for each of my 6.5" Morel drivers.

My amp has an output level (not the voltage gain dial) I would think it is the same as the level found on the crossover section of my head units and many of the high end HU's that have some sound processing.

Before I post my questions, here is more information. Using the passive bi amping my mids and tweeters, 80Hz HP.

With the channels NOT bridged, I had the output level (supposed to be used to balance front from rear channel levels, not related to the main volume) at 92% of the max output level. The amp puts a max power of 100W/ch. With some songs at volume 24-27 out of 35 max,I could hear noticeable clipping on my mids on most average to typical music with some bass.

Now with the bridged channels almost 3 times the power, The sound was not noticeable louder, at 24 out of 35 max, it was cleaner, no clipping at all and it appears that I could turn it up higher but I barely set at 24 for no more than 5 seconds since I was afraid it was too much power for my mid bass.

I decided to set the output level at 82% to start , (10% less than before when the amp was not bridged) same thing no clipping, clean sound, in fact I turned up to 30 with some tracks and it seems that my drivers can take it and no clipping, but I do not want to go higher than 25-27 although I feel I can and border line feel the need to try it higher.

My EQ levels are all pretty much below flat except for a maybe 4 bands out of 9 that are flat.

1. Why would it clip at 24-27 with less power (clean 100/ch) and now it does not? Is this how extra power behaves, more clean sound rather than much louder? (I heard that before, now it seems to be a reality check for me)


2. Does that output level that functions as a separate individual level affects the power if reduced, or is is like a volume?


3. Should I increase the output level at least another 5% or leave there to protect my mid bass from extra power although no clipping has been heard?


4. How will the power affect my mids once I connect them back to active pass?


Thanks in advance for any help you can share, I know, a lot to read, I hope did not have too many typos and grammar issues.

Al

 

[SO20thCentury]

Exciting! ....but hmmm... ?
Sorry but I've got no help and since mine still aren't installed I'm interested in what you find.
Do you just set the output gain by ear? But different from using the old turning it up til it clips and back it off method? I don't see that covered in the manual.

 

[SO20thCentury]

Just thinking...since the amp pushes 200w at 2ohms bridged are your Morels a 2ohm load? Sorry if it's a stupid question but I'm one of those people you need to draw a picture for

 

[autokraftgt]

Anyone can correct me if Iam wrong, but with less power, you may have been introducing some distortion/clipping. Now with more clean power, you are reducing the distortion, and are perceiving less volume which is not the case...just less distortion and cleaner output.
I would increase the output level a bit to see if you like the sound....watts do not damage speakers...distortion/clipping does...
when I went from 90 watts per midbass to 360 watts per midbass....my first impressions were not the increase in output (which was minimal btw) but less distortion, more dynamics, and a happier speaker.
my take on it....feel free to correct me if I'm wrong guys...

 

[Fast Hot Rod]

1. Why would it clip at 24-27 with less power (clean 100/ch) and now it does not? Is this how extra power behaves, more clean sound rather than much louder? (I heard that before, now it seems to be a reality check for me)

It's because you are confusing "clipping" with "distortion." While clipping can cause distortion, it's not the only reason that we can hear distortion.

Clipping is what happens when you over-drive a channel and the top & bottom of the waveform is 'clipped off' because the amplifier runs out of headroom. If you had an oscilloscope on it, you would see the clipping long before you heard it... and as you went further, your ears would hear it as distortion.

This is what clipping 'looks' like. The signal on the left is right at the limit of output. The signal on the right has been 'clipped' because the amp reached it's headroom:

When you bridged your amp, you are now essentially increasing your voltage output... so your speakers are able to receive more power without clipping the signal, which is why you didn't hear any distortion.

A speaker has both physical (excursion) and thermal limits. A speaker will normally take a bit more power than advertised, but be careful... you don't want to over-heat the voice coil. Having more power is 'normally' better than not enough power, provided you setup the amps such that you aren't pushing the drivers past their physical and thermal limits.

2. Does that output level that functions as a separate individual level affects the power if reduced, or is is like a volume?

On the JBL MS-A amps, there is an Input-Level control and a separate Output Gain Adjustment.

The Input Level control sets up the amplifier so that when you have the volume up to maximum, the amplifier knows exactly how 'large' the signal will be at maximum volume. (Peak voltage.) It is essentially 'scaling' the input so that it knows whether or not you have a 0-2 volt input, 0-5 volt input, etc...

Once the input is setup, the Output Level control is used to set the output relative to the other amplifiers/speakers. So let's say you had a sub amp, main amp, and maybe were driving tweeters from your HU. You would be able to play the tweeters at max volume with no distortion, measure the output with an SPL meter, then go back and set the levels of your mid bass and sub based on the tweeter output. Essentially you are trying to balance the three outputs so that then the HU volume control is at "27" that each of your speakers (tweeter, midbass, and sub) are all putting out about the same SPL.

3. Should I increase the output level at least another 5% or leave there to protect my mid bass from extra power although no clipping has been heard?

You should balance your output levels so that every channel is relatively equal (SPL output) to each other, all channels driven without audible distortion.

One way to test this is to set the Input-Level per the manual. Turn the Output Level to something low... say 20-30. Then listen to your source material and start cranking up the volume. When your HU starts to distort, you will hear it... record that number. You said that your HU goes to 35... you might find that you have no audible distortion even at 35... but more than likely, you'll hit the top at around 27~32ish. Record that number when you hear distortion, then back it down a click or two until it's clean. You now know how loud the HU will play without distortion. (For giggles, let's say it's 27 for this example.)

Now with your volume set at 27, take that Output Level control and start cranking it up. As it gets louder, you will start to hear some distortion. That's the limit of the driver... record that number at the amp's Output Level, then back it back down. If you have an SPL meter (or app on your phone) record the SPL output level. Now do the same thing with your sub.

Once you have the maximum output levels (number from the JBL output level on the display) and the SPL outputs of each channel, do a simple comparison. If the sub is louder than your mains, then use your mains SPL level as the maximum level. Turn the HU back to 27, then adjust the SUB output level until it's SPL output matches the recorded level of your mains. Turn the volume down, then adjust the Main Output to the previously recorded level. Your sub and mains should be really close to the same SPL output level. (You may wish to go back later and make a minor adjustment to suit your tastes.)

4. How will the power affect my mids once I connect them back to active pass?

Going active will change your settings... you'll want to balance each channel separately if possible. Or at least balance the tweeters to the mids, then those to the sub(s).

Thanks in advance for any help you can share, I know, a lot to read, I hope did not have too many typos and grammar issues.

Al

Naw... you're good. Hope this helps.

 

[Fast Hot Rod]

watts do not damage speakers...distortion/clipping does...

Both will, actually. While clipping and distortion will cause problems, having too much current/wattage will heat the voice coil past it's limits and cause damage.

Music being dynamic and all, you'll probably reach the physical limits of the driver and hear the distortion and be able to back things down before you destroy the speaker... but given the amount of bone heads I hear with it "cranked up to eleven" on the streets, this may not always be the case. :blush:

 

[Alrojoca]

Fast Hot Rod
Thanks! Good info.

I assumed the amp was clipping and not the speaker, with less power to the mid bass, since more power did not produced the same thing I was hearing before. Now with more power only cleaner sound is heard.

If Clipping is dirty voltage or dirty power by the amp, and only speakers can distort, is there a difference in sound between a speaker being overpowered and an amp trying to play at max power and clipping? (Audible difference between Distortion vs clipping)

Does keeping the amp's output level lower, provides any protection to the midbass or from overheating the coils?
I think this was answered, in a way, although I never saw the output level as a voltage gain type of setting, I thought the max level was the point of where distortion or clipping should be at, and from there simply lower it as needed to match the tweeters or subs in whatever order they need to be done, since location and distance is a factor to balance it, and yes I need to use a mic and app, to get a more accurate output.

The midbass iplays cleaner with more power, and it does not try to keep up with the sub. Now I think I may have to increase the the sub's LP, tune and balance, the sub since they are not blending compared to how it was before.

Perhaps the bass I was hearing with less power and not at higher volume levels was simply clipped voltage from the amp?



SO20thCentury
The morels are 3.8 ohms, 4 ohms nominal, they handle 140W each, and I have read they can take way more than rated. I hope the info on this thread helps you

 

[Fast Hot Rod]

Fast Hot Rod
Thanks! Good info.

You're welcome.

I assumed the amp was clipping and not the speaker, with less power to the mid bass, since more power did not produced the same thing I was hearing before. Now with more power only cleaner sound is heard.

Your assumption is correct, because speakers never really "clip." Clipping is a very specific term, and is referring to the top of a sine wave being "clipped off" when the amplifier runs out of headroom.

If Clipping is dirty voltage or dirty power by the amp, and only speakers can distort, is there a difference in sound between a speaker being overpowered and an amp trying to play at max power and clipping? (Audible difference between Distortion vs clipping)

It might be easier if you read this:

Distortion, Clipping, and Square Waves

Does keeping the amp's output level lower, provides any protection to the midbass or from overheating the coils?

Yes.

I think this was answered, in a way, although I never saw the output level as a voltage gain type of setting,

That's probably because of the way that your JBL amp is designed vs. other amps. Older amps normally had one gain knob. The gain circuit was designed so that you could allow for variance between input levels to the amp. That way, if one HU had an output of 0~5 volts, the amplifier could be adjusted such that it put out 0~100 watts. If the next guy comes along and his HU only put out 0~2 volts, he'd only get 40 watts out of the amp. So he would adjust the gain control so that the input stage of the amp saw that 0~2 volts as minimum and maximum, and would then put out 0~100 watts.

Your JBL amp accomplishes this in the Input-Level setup. Where the JBL amp is different is that it has an additional Output control, which then allows the output to be adjusted so that each speaker can be dialed in for a specific output without the need to adjust the input stage. This allows the input stage of each amp to receive the exact same signal, but allow for variable output adjustments. It's essentially doing the same thing, but it does it in a different way.

I thought the max level was the point of where distortion or clipping should be at, and from there simply lower it as needed to match the tweeters or subs in whatever order they need to be done, since location and distance is a factor to balance it, and yes I need to use a mic and app, to get a more accurate output.

In your particular case, you have speakers that can handle 140 watts safely. When you powered them with 100 watts, you heard the amplifier run out of headroom and start clipping. If you backed it down there, you'd be good... but as you already know, you aren't getting the most out of your system that way.

So by bridging your amp, you now have more available power to your speaker. (Approximately 200 watts.) Now it's not the amplifier holding you back from louder SPL levels, it's the ratings of your speakers. Can they handle more than 140 watts? Probably... but the manufacturer has done a lot of testing and that is the limit that they feel comfortable telling you that it can handle and still provide you with great sound for years to come. Given the transient nature of music in general, occasional peaks over the rating probably won't hurt it... but extended periods of heavy/loud listening very well could. It's up to you to decide where to find that balance between output and longevity.

The midbass iplays cleaner with more power, and it does not try to keep up with the sub. Now I think I may have to increase the the sub's LP, tune and balance, the sub since they are not blending compared to how it was before.

Any time you make changes like that, you'll want to retune the system. Sometimes our ears play tricks on us... and sometimes distortion (or vibrating panels) give the illusion of more bass. I assume that you're using active crossovers for the sub and main speakers? 80hz? 12dB/oct?

 

[SO20thCentury]

FastHotRod thanks for the excellent tutorial of setting up these amps and descriptions of exactly what is happening inside of them with the adjustments made outside. I will keep it as a reference for when I finally reach that stage. Unfortunately your sig matches my build.:mean:

Alrojo are you getting it dialed in to make a great improvement in the sound? Your news is exciting to me cuz I've still got nothing to hear

 

[Bayboy]

Perhaps this may clear a few things up a bit although some comments are pretty much spot on. The MS-A1004 is not 200 bridged. It has been tested to do 308 @ 13.8 volts, 400 @ 14.4, but we'll stick to the 308 since that's what most alternators run at during normal driving and at least compensates for slight voltage drop back towards the amp.



Plain & simple.... you're hearing better dynamics due to having more headroom for peaks even though you're not using the available average power. As far as the drivers, the extra 40 watts handling isn't what is really that big of a difference. It is the fact that handling has been increased by crossing them up. Mechanical handling has been increased. Has been since they were installed and crossover applied.

 

[Alrojoca]

Thanks again, Fast Hot Rod, and Bayboy I'm glad you posted, since we know this amp's power is under rated.

I have just over 3 hours of listening, I still need to tune and EQ and I was just waiting to post my findings and questions.

Output gains are still at 82% for the mid bass in bridged mode.
Vol 20-22 is ideal now while driving, while before it had to be at 26-27 with average to high vol tracks and occasional amp clipping with some tracks.

I still do not hear distortion even at volume 27 after the amp was bridged, I have passed that mark with very low volume tracks. I'm afraid to even go above 24 with average to hi vol tracks.

The sub hp is at 100hz now, still 12db slope active. Having the amp's sub output level at 92% and the HU sub level from 0-15 makes it difficult to know where to find the correct point, it's easier to use the HU sub's vol, eventually I'll find the point that suits my taste, and I know this a YMMV thing based on the music type and tuning by ear.

When I set my gains, the HU vol was at 32, the amp's gain dial is near the minimum of a turn for both 2 pairs of channels (1 dial per each pair)
Loudness is off, and all Eq bands are flat or below flat.

These are the questions I have now, based on the power available from this amp

If amp's putting 300W/ch in bridged mode, with the output level at 82%, does it mean aprox 240W/ch based on the 18% output reduced and so on if reduced more?

And as long as I do not hear distortion, the coils are not overheating with 240W each and keeping a HP of 80hz or higher?

Will I be better off to do the gains again at max vol of 35 or simply lower the amp's output another 5-10 just to protect the mid bass drivers ?

Thanks for the help and I'm glad some can benefit from this thread and post their questions and concerns

 

[Bayboy]

I'm not familiar with that Alpine deck and where it actually begins to clip. That could be of help although I understand you may be wanting to leave a bit of fudging room for low output recordings.

I wouldn't concentrate on too much where the gains are at since it's a complex amp. Just as long as you're not too far off with the volume being at it's cleanest maximum while the drivers are close to maxing out without being damaged, I think you'll be fine. Being too conservative on the gains makes the listener suffer when recordings are low (can't get enough output). When recorded well, you can always keep a light hand on the volume knob. How much power is actually going to the drivers is of little importance. A few watts here or there is of no audible difference. It's the average of power that you need to worry about... staying too close to what they can thermally handle. What that number is? You'll know when they quit. But I'm sure you won't be that foolish.

 

[SO20thCentury]

It's the average of power that you need to worry about... You'll know when they quit.

Would it be any benefit to set gains using a low volume recording?

 

[legend94]

These amps look intriguing to me. What is the overall sq like?

 

[SO20thCentury]

Besides the flexibility with built-in crossovers, I bought these because they're said to add no noise. Wish I had some firsthand experience of sq by now. Could turn this into one of those "class D amps sound best" threads

 

[legend94]

We don't need another one of those! My question should have been more about the quality and ease of use. I have the mono one but have not tried it out yet. I had thought about getting a couple 1004 and bridge them to mids and tweets.

Anyone have these under seats?

 

[SO20thCentury]

SQLNovice had them under his seats
http://www.diymobileaudio.com/forum...ery/165774-2011-scion-xb-first-build-log.html

Oops, didn't have them under seats!

 

[Bayboy]

Would it be any benefit to set gains using a low volume recording?

Of course the normal way would be to set gains using some form to detect clipping, but if you're concerned with having enough volume on low level recordings, of course you can. I'd be careful with it though, you will have to use a light hand on the volume knob with optimal recordings.

 

[Ainuke]

Just my ¥2.

Using test tones, finding the point on the volume dial where the head clips becomes *infinitely* easier. The clipping comes out as a harmonic. So dial down the gains and play test tones (referenced to -6db, as this is the most common recording level; although you can also repeat with 0db and -12db to get a feel for what range you have to work with depending on whether you have loud or soft recordings). I can't say how evenly you will encounter clipping on you head, but mine started around 1K and was variable up until 3-4K. Everything above and below and above that was super-clean up until 35/40 on the factory knob.

So then you get to decide whether you can tolerate slight clipping and in what band (and which drivers get those bands). For example, if the only place you're clipping (pre-EQ) is around 8K, then you're likely to be cutting that band during EQ anyway, and a quick kiss of clipping may be tolerated...

 

[Alrojoca]

Thanks for the suggestions

No major updates, just playing with the EQ and output levels, my ears got used to the sound, and I'm having higher expectations every new time I play music, maybe I'm getting greedy, wanting to turn the volume higher, knowing I'm getting in a danger zone even if don't hear signs of stress, for that reason I lowered the output levels 2 points just in case I turn it up higher than number 27.

I'm not sure if I would go 100% with pasmag test ratings, I'd like to assume it's accurate, everything they test tends to have nothing but positive reviews.

As far as SQ, I'm not picky I would say it's as good as any or most good quality class D amp's, it's not as smooth as some good class AB amplifiers. I like the size and the efficiency of only needing 8 gauge power wiring, the DSP has some limitations but it works well for what it does.

I would try setting the gains at volume 30 or 32, 85-91%, with the JBL CD to get the check marks, if I was going to bridge it, then try high and low volume tracks and decide if it needs to be set again at a different volume.

Feel free to PM me if help is needed with an MS A amp