MM 6501 Hard to drive!

Rudolff zigray

Hello everyone I would like to introduce myself, My name is Rudolff Zigray and I am very well known in Hi End Home Audio. I am very knowledgeable in home audio a bit ignorant with car audio.

I recently purchase the MM 6501 MM 561 and a mm10 for my VW Eurovan. I have an aftermarket HU Kenwood Excellon X994. I cant drive these speakers with this head unit. It is rated at 22 rms with 60 watt peaks. Is it possible something wrong with HU or install

Here are some of my observations.

1. Somewhere I read the most idiotic statement in the polk specifications for this speaker. It read something like these speakers use a low 2 ohm impedance to draw extra power safely from your HU (compatible with virtually all factory or after market head units)

A) This seems really stupid to me. A low impedance is always harder to drive. There is nothing safe about a 2 ohm load. A speaker with 8 ohm or even 16 ohm will drive effortlessly and far easier than a speaker at 2 ohm. 2 ohm is very rough its about as bad as it gets....infact it can there is only one other worse situation 1 ohm. So what the

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is crutchfield talking about.

2) Most HU are rated at 18 rms with 40 or 50 watt peaks. So the kenwood should fair better than most.

3) All speakers are distorting horribly when I try to turn the head unit up to decent spls. I cant turn it up to 3/4 volume with everything falling apart. Sounds terrible. Sounds find at easy listening levels...(grandparent listening level)

4) Most reviews of these speakers if not all post that they are using a separate amp to drive these speakers.


5) Could the stock wire be to low of a gauge creating resistance?

6) Has anyone had this same problem trying to drive these with a head unit?

Any help or comments greatly appreciated.

Kindest regards
Rudolff

arun1963

HU's are a poor source of power. The 20 watts RMS, is at something like 3-5% THD. This is what your speakers are reproducing and the reason they sound bad. With a HU you'd basically run of clean power around 40% of max volume. That's on the good units like yours.

Get a 4 ch amp and bi-amp the 6501. Give like 80-100watts per channel. Yes the speaker is 2.6ohm as most car amps are stable at 2ohms and you get more power. That's the logic. In a car environment the 2 and 1 ohm loads are perfectly fine. The equipment has to be stable at these loads.

If you want the 2ch reproduction in your car, you need a ton of dsp to tune around all thats wrong in your car environment. Your hu doesn't provide this. If you just want decent sound without distortion, then just get the amp, seal the doors and be done with it.

Rudolff zigray

Thanks for the info I really liked your comment on HU's " you only get clean power to about 40% of volume. That is exactly what I am experiencing. As soon as i go to 50% volume I hear sound degrading.

An Amp was my next step...well my only step from hear. I was pretty thorough about my install. I dynamatted and insulated the doors very well. I mounted the tweeter about 10 inches from the woofer to get seemless intergration between the two. I am not so sure I achieved this. Imaging is less than to be desired.

I think the Eurovan may be a tough vehicle for good sound. The seats are very high. The woofer is located almost at the bottom of door panel (which is about caff level when sitting. I flush mounted the tweeter at the door handle tab (auto windows) This puts the tweeter slightly above and infront of the knee when sitting in the chair. Nothing is abstructing the tweeters firing straight across at each other. But I find this may be a little low? Also the way the panel and the mount is for the 6.5 woofer, it has the woofer pointing slightly down word. Pretty crappy huh? I would say about 10-15 degree tilt downward.

I still have a pair of mm521 to install in the rear and a mm10 sub.

My next step was to try a 1998 Clarion 5 channel amp. Why did you suggest bridging I was hoping to use this amp to drive all 4 drivers and possibly the sub. Again not afraid to show my ignorance with car audio. Home Audio is my world.

Again why bridge a 4 channel amp? Why not just find an amp with more power?

I would like to say this. It should be stated that you can not drive the mm6501 with a head unit. At least not very loud at all.

arun1963

Rudolff zigray wrote: »

An Amp was my next step...well my only step from hear. I was pretty thorough about my install. I dynamatted and insulated the doors very well. I mounted the tweeter about 10 inches from the woofer to get seemless intergration between the two. I am not so sure I achieved this. Imaging is less than to be desired.

You've got a fair bit of the install covered. Imaging in a car requires two different types of processing. Time alignment and independent L/R eq. If you want the imaging bit, you need the p-880 or a processor.

Rudolff zigray wrote: »

I think the Eurovan may be a tough vehicle for good sound. The seats are very high. The woofer is located almost at the bottom of door panel (which is about caff level when sitting. I flush mounted the tweeter at the door handle tab (auto windows) This puts the tweeter slightly above and infront of the knee when sitting in the chair. Also the way the panel and the mount is for the 6.5 woofer, it has the woofer pointing slightly down word. Pretty crappy huh? I would say about 10-15 degree tilt downward

The best location for the mid bass is down low and as far forward as possible. Seems you are set on this count. Don't know about the mids firing downwards though. It would take everything more off axis, see if you can correct this. Height cues are 2khz and upwards. This is largely your tweet territory. So you need to mount the tweets physically higher. Dash level or A pillars. Again if you care about the imaging then you do need time alignment at the very min.

Rudolff zigray wrote: »

still have a pair of mm521 to install in the rear and a mm10 sub.

Again if you're after imaging, you don't need rears. But yes you need the sub. You're not going to pull the sub presentation from the front w/o TA.

Rudolff zigray wrote: »

My next step was to try a 1998 Clarion 5 channel amp. Why did you suggest bridging I was hoping to use this amp to drive all 4 drivers and possibly the sub. Again not afraid to show my ignorance with car audio. Home Audio is my world.

I wasn't suggesting bridging, I was talking about bi-amping, where all four drivers of the MM6501 would be running off individual channels of the 4ch amp. The bridging bit referred to folks running the comps of 2 front amp ch's and bridging the rears to run the sub.

Rudolff zigray wrote: »

Again why bridge a 4 channel amp? Why not just find an amp with more power?

Because its cheaper.

Rudolff zigray wrote: »

I would like to say this. It should be stated that you can not drive the mm6501 with a head unit. At least not very loud at all.

Agree.

Rudolff zigray

Sorry I re-read all your posts, and I now see that you specify bi-amp! my bad! I know exactly what your talking about and should of not assumed bridging. Interesting suggestion?

Bi Amping in home audio is common. the built in powered sub. In two channel home audio is a bit easier in many ways. Good speakers are designed for time alignment by physical design. Usually by natural taper of the front baffle. Most designs are 8 or 4 ohm and easy to drive. More watts almost all the time, degrade sound. The best amps in the world, (my opinion and the opinion of many I respect) use the 1 of 3 tubes.....the 45 tube (in single ended SET) will give you 1.5 watts max. 71a tube ( in single ended SET) will only give .75 watts. very beautiful tube hard to use....and the much regarded 2a3 which will give you 3 watts in SET. All these tubes retain there magic in push pull designs which will double there out put making them a bit easier to use. Of course the speaker choice for these tubes is limited to horn design. Avantgarde Duo's, is a perfect example of about the finest plug a play speaker in world. The Oris horn, or a Gotto or ale horn system will defeat the Duo but you must know a bit more and build them your self. I have both the Duo and a my project Oris horn system. Rambling sorry

Back to Bi amping? I have never seen any one bi amp a tweeter in home? The tweeter will be far more easier to drive then the woofer and there for the single amp driving it will be in a entire different environment then the amp driving the woofer. The same two amps in different environments will sound different further making seamless integration a ****. You would think Polk would have built a little time alignment processing in the crossover even if its only passive. Especially in a coaxial speaker where they mount a tweeter infront of the woofer. Maybe I asking too much? Tweeters being far more direction and high frequencies travel faster I felt bring the tweeters closer to my ears I would have a mess on my hands. I have not looked at this processor you mention. I have been reading about car audio obsessively for two weeks now, and still know very little. ugh....

The kenwood unit has a little alignment processing in it. It asks how far the sub woofer, front left, front right, rear left, rear right, are from listening position. But I bet this is not what your talking about. Based on your posts, I think I am talking to a guy who has done and won these competitions I keep hearing about. I wish they had something like that for home audio I would have to change my name to Larry Holmes.

My friend who is helping me install has won competitions with another gentleman I believe. He seems a bit aloof about my install. I keep bringing up all these points I read about and he knows them but never suggests them. Also I admit I was not trying to delve in to this wholeheartedly. I was trying to keep with in a budget and see how good it could get. Hell I wasnt planning on buying separate amps and now its absolutely necessary.

I would like to thank you for all your help. I will look at these processors and post back.

be well,
Rudolff

arun1963

Rudolff zigray wrote: »

Bi Amping in home audio is common. the built in powered sub. In two channel home audio is a bit easier in many ways. Good speakers are designed for time alignment by physical design. Usually by natural taper of the front baffle. Most designs are 8 or 4 ohm and easy to drive. More watts almost all the time, degrade sound. The best amps in the world, (my opinion and the opinion of many I respect) use the 1 of 3 tubes.....the 45 tube (in single ended SET) will give you 1.5 watts max. 71a tube ( in single ended SET) will only give .75 watts. very beautiful tube hard to use....and the much regarded 2a3 which will give you 3 watts in SET.

Tube amps can sound nice in a home 2ch set up. In a car enviornment, you need power. The car has a much higher nosie floor as compared to your home. This cancels out a chunk of your lower end. Reflections of the glass and all the hard reflective surfaces in the car would cancel out some of your mids and highs. Hence to give a decent impact to your stage, you need the extra power.

Rudolff zigray wrote: »

Back to Bi amping? I have never seen any one bi amp a tweeter in home? The tweeter will be far more easier to drive then the woofer and there for the single amp driving it will be in a entire different environment then the amp driving the woofer. The same two amps in different environments will sound different further making seamless integration a ****. You would think Polk would have built a little time alignment processing in the crossover even if its only passive. Especially in a coaxial speaker where they mount a tweeter infront of the woofer. Maybe I asking too much?

Yes, maybe you are asking for too much . I don't think theres any time alignment in the xovers. In a car, you're bi-amping to control each driver seperately. Most passive xovers split the signal fairly low. 2-3khz. This has the effect of making most tweeters sound harsh. Bi-amping passively, allows you to attenuate the tweets so that this harshness is reduced. If you run active then the benefits of bi-amping really come thru.

Rudolff zigray wrote: »

Tweeters being far more direction and high frequencies travel faster I felt bring the tweeters closer to my ears I would have a mess on my hands. I have not looked at this processor you mention. I have been reading about car audio obsessively for two weeks now, and still know very little. ugh....

Yes tweets are more directional than mids, cause the cone is much smaller. Speed of sound varies with the density, temprature, humidity and molecular weight when we talk about a gaseous medium, like air. Quite sure that in a given medium at given conditions, 20hz and 20khz would travel at the same speed.

Rudolff zigray wrote: »

The kenwood unit has a little alignment processing in it. It asks how far the sub woofer, front left, front right, rear left, rear right, are from listening position. But I bet this is not what your talking about.....

As long as you can enter variable values you should be ok. What is the range in which you can enter these values?

Rudolff zigray wrote: »

My friend who is helping me install has won competitions with another gentleman I believe. He seems a bit aloof about my install. I keep bringing up all these points I read about and he knows them but never suggests them......

No issues like that here. Macs always been more than helpfull to anyone who asks.

Rudolff zigray wrote: »

Also I admit I was not trying to delve in to this wholeheartedly. I was trying to keep with in a budget and see how good it could get. Hell I wasnt planning on buying separate amps and now its absolutely necessary......

I would suggest that you take this in steps. Get the amps, bi-amp the fronts passively, hook up the sub and if you really want to, run the rears off the HU. Use the fader depending on if you have someone in the back seat or not.

Get comfortable with this set-up and whatever tuning features you currently have. You can then decide if you want to go further by adding a processor / changing HU, going active etc etc.

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... I agree with your assessment of the "2 ohm load for safely drawing more power from the head unit" being an idiotic statement. I've seen head units burn up trying to drive 4 ohm loads. Most of the head units use integrated amplifiers instead of true transistor based channels... which makes head unit "power" the worst (audibly) and the worst (electrically) and the worst (thermally) you can get.

Your head unit is rated for 'whatever watts at whatever ohms' -- in most cases, hooking a 2 ohm speaker up to a 4 ohm head unit channel will void that head units warranty.