My stereo upgrade project

[Matti777]

I hear some like the bass boosted out to 300hz or more. Maybe I will try that sometime on another channel. I did deaden the doors and spare tire well. Deadening the spare tire well made a difference. I have a whole box of Noico left over that I don't know what to do with. My sub is behind the passenger seat so I am not as worried about the trunk area.

Sponsored

 

[StangTime]

I created a Crutchfield curve text file too but I think I will work with the Hanatsu based on its popularity.

The other issue I have to resolve is how to import REW EQ settings into miniDSP 6x8. miniDSP wants a different file type than REW exports. One is a txt file and one is an eq file....I can't remember which is which off hand. I have the basic miniDSP equalizer selected in REW.

EQ filters can also be entered into REW manually and it shouldn't take too much work if you are using parametric. I have no option but to do manual entry as my DSP is a 31 band graphic EQ.

 

[Matti777]

EQ filters can also be entered into REW manually and it shouldn't take too much work if you are using parametric. I have no option but to do manual entry as my DSP is a 31 band graphic EQ.

Yes I created manual EQ changes in REW at first and then fooled with the auto EQ. I have manually entered EQ changes into the miniDSP software. There are only 6 per channel so quite limiting as I am finding out. Maybe that is a good thing. Maybe I need the C_DSP 6x8 plug in...tba

 

[Matti777]

Its snowing and we are expecting up to a foot so I spent a few hours in the garage doing the first round of tuning. To be honest I have probably spent 20+ hours researching, playing with the software and taking preliminary readings. So I took a few readings on each side and averaged each side. When I went to EQ there was an obvious problem. Looking at the target curve there was a significant roll-off at 6k hz. I can only assume that this is due to the large format tweeter off axis response. I did eq the left and right mid drivers using the REW auto tune . The stereo does sound good. I'll plug the factory tweeters back in and see what that does to the RTA readings. If it helps I will perhaps get some better tweeters and figure out how to run them off the same channel.

 

[Cathul]

Well, ok. The resulution sucks on that screenshot (really, a 20db resolution on such a screenshot basically shows nothing).
Aside from that it doesn't look bad for a 1/6th octave smoothing, but i guess if you raise the resolution to 5db increments (i.e. it shows 55/60/65/70/75/80 and so on db on the vertical scale) it wont print as good as with the current resolution.
But, this doesn't matter if it sounds good.
Remember, what measures good doesn't necessarily have to sound good. The only thing that matters is that left and right side are within 1-2 db to each other to have the same tonality on both sides. And tbh... with your miniDSP you are not able to adjust everything, but the major problems.
And yes, you will have some severe roll off with larger tweeters in a two-way system, especially in the mustang where the tweeters are mounted the way they are and you've put them into an even less optimal position for staging et. al.
Just take a look at the left stock tweeter. It's 60-70° off axis to your listening position. The right tweeter should measure a lot better though into the upper highs. At least that's the case with my setup. If it measures ok on its own maybe you can dedicate a small 2-channel amp and feed it from your DSP if possible? You would then change the SB29 for a dedicated midrange (just check the depth of the midrange. Max is 1.5 inches i think before you touch the window).

Granted, you put your tweeters into the midrange position. Maybe you can angle them to your listening position to counteract the off-axis behavior to some degree?

What you could try to do for your tweeters is to raise the gain on the tweeters so the upper highs are near the target curve and then pull down the rest with the EQ (if possible). If you cannot pull down the rest with your EQ you should leave it as is, but please stay away from raising the upper highs with the EQ after setting the gains for your tweeters.
You might need to adjust your xover settings, too to acommodate the higher gain on the tweeters, because the xover point will move down into lower frequencies if you raise the gain on the tweeters.

All in all when looking at the specs of the tweeter you maybe should leave it as is. Putting the tweeters into the stock location might not be possible due to the size of the magnet. Especially if you think that it sounds good. I myself am thinking about lowering the tweeters response to a steeper roll-off that i have now as the interior of the mustang is quite small and you're near to the tweeters when sitting in the drivers position. But i'll have to wait till my wife is gone shopping or so to avoid her dirty looks when i go to remeasure my car again.

 

[Matti777]

I did think of a few things to try. Raising the gain on the tweeters just put a hump in the 3k range. I would have expected better right side response but that is not the case. Perhaps they don't like facing each other? I do have room in the housings to angle the tweeters with a little fabrication. I will first try plugging the stock tweeters back in and see what that does. We got 20cm of snow yesterday so winter has set in and I have 5 or 6 months to sort this out.

 

[Cathul]

EQ the hump when you raise the gains.

 

[Matti777]

Raising gain on the tweeter channels put a hump in but didn't change anything in the roll off area. I plugged in the factory tweeter on the right side and it raised the level a few db but didn't change the roll-off. The mic is 90 degrees to the SB tweeter so you would expect a roll off on the upper frequencies but this is the way everyone takes measurements. I assume that this means that its either the way I am measuring/set-up issue, a speaker positioning issue, or perhaps vehicle acoustics. I think its good enough but I would like to hear a flatter response in the upper frequencies to decide what I like. In the meantime I will continue another round of tuning on the mid bass.

 

[Cathul]

The roll-off will be shaped by equalizing the response. For this the target curve needs to be below the roll-off, i.e. the gain needs to be higher than the target curve so that the area in question is higher than the target level. Then pull down the area higher than the curve down with your equalizer.

 

[Matti777]

The roll-off will be shaped by equalizing the response. For this the target curve needs to be below the roll-off, i.e. the gain needs to be higher than the target curve so that the area in question is higher than the target level. Then pull down the area higher than the curve down with your equalizer.

I will fool around with REW tonight and see what I can do although I am not thinking this will be solved with EQ but I could easily be wrong. I had a thought.....I wonder if there is still interference from the factory HU EQ or capacitor? I will double check that EQ is still disabled in Forscan and look at the wiring diagrams. How was the factory 3.5 mid crossover controlled?

 

[Cathul]

The factory mid and tweeter are connected in parallel with the tweeter protected with an inline capacitor.

Ok, before you try the following make a backup of your current preset!

In the REW eq just pull down the target level down until your measured response at 20kHz is at the level of the target curve. This should bring almost all of your tweeters response above the target curve. Now just cut (or run autoEQ in REW) until the predicted response matches the target curve. Maybe you need to adjust your crossover as well to get the slope near to your target curve again.
After that play midrange and tweeter together and raise the tweeters output gain (or amp gain if possible, but use this option after the DSP output gain) until the tweeters level is at the desired target level of your target curve.

 

[Matti777]

If I don't find any other issues I will give that a try.

 

[Matti777]

Ok now I have found out that the REW RTA app can't be in spectrum mode as that will change the slope of the response curve. Apparently I am not the first to make this mistake as it is the default mode and the curve looks good as compared to many of the RTA modes

 

[StangTime]

Ok now I have found out that the REW RTA app can't be in spectrum mode as that will change the slope of the response curve. Apparently I am not the first to make this mistake as it is the default mode and the curve looks good as compared to many of the RTA modes

Yep. I bet you aren't the only one.

I would be interested in seeing your before and after EQ plots with a 5db vertical scale.

 

[Matti777]

Yep. I bet you aren't the only one.

I would be interested in seeing your before and after EQ plots with a 5db vertical scale.

I'll probably get a new set of readings in the next few days. Its hard to show the whole plot with 5db scale as you have to expand it to a narrow frequency range. Perhaps there is a way of doing it that I have not discovered yet.

Sponsored