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Personally, I'd zero out all the trim levels, disconnect the speakers from the amps, and set the amp gains using a multimeter and with the trims all at zero.

The trims should be used to make balancing adjustments between the speakers, not for overall output level control.

Assuming you have the 5.25" running on two of the amp channels and the tweeters running on the other two, you can use the amp gains to set the balance between the mids and highs as well. It looks like you were using the TwK-88 trims to reduce the tweeter output to balance out with the mids ... when you could use the amp's gain instead to do this.

Setting them to max voltage with a multimeter gives you the max gain you should run. Turning the gain lower is fine, if it's needed to provide a balance between drivers.
 

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Discussion Starter · #42 ·
So on that amp.....

The "SENS" knobs are the gain settings. You're running from the HU, to the TwK-88, then from the TwK-88 to the amps ... correct? So the gain/sensitivity of the amp should be set to align with the TwK-88's RCA output, not the headunits.

The amp is rated for 75wpc @ 4 Ohm, so you'd want to set the gains on it to hit around 17vAC. (75w x 4Ohm = 300 ... sq/rt of 300 = 17.32). You would do this with the speakers disconnected, playing a test tone with the headunit volume up around 75-80% (or whatever the max level is without causing clipping), and then using a multi meter with it set to AC voltage.

The rest of the amp settings should be set to 4CH input config, and both X-OVER switches set to "FULL".

If the X-OVER switch for the channels driving the 5.25" speakers is set to HPF, this could also explain them not playing much below 300Hz.

If it were me, I'd definitely set the gain on the sub amp using a multi meter. The sub is rated for 750w, and that amp is rated for 760w @ 2-Ohm. So it's a great match up. 750w would be around 38vAC with a 2Ohm load (750w x 2Ohm = 1500 ... sq/rt of 1500 = 38.72)
On the off chance that I made such a rookie mistake I just ran outside to look. Sadly, both crossovers are set to full. That would have been such a great fix.

Okay, checked the specs, looks like the TwK-88 has outputs of 4v at the RCAs, so at least that much is matched. My setting is floating between 3.5 and 4 on the input sensitivity at the moment.

Okay, so as far as the MM testing, from what I've just read:

Set HU volume at 75%
Speakers disconnected, set everything in the DSP at baseline. (trim levels, EQ)
For the 4channel play a tone at 1khz
Raise the gain until I reach 17vAC on each channel
For the mono play a tone at 60 hz
Raise the gain until I reach 38vAC on the output
Put it all back together.

Question:

The HU volume is set to 75%, but I have a separate volume control with my DSP. Should I have that turned up to 75% as well?
 

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So the RCA voltage specs are max voltage. The voltage output of an RCA is variable, dependent on the volume level being played. The typical approach is to set the volume stages (HU and DSP) to the max level you would ever turn them to, or ... to the max level where clipping would start, and then set the gain/sensitivity of the amps based on that. So you get maximum clean output from the amp (up to the limit of the speakers connected of course) without introducing any clipping. If you then need to adjust gains to balance different speakers, you would only reduce the gains from this point, but never increase them.

The 75% recommendation for the head unit volume is a general rule-of-thumb, which assumes there's no clipping of the signal from the HU at 75%. Some head units (like my 80PRS) can go to 100% volume and still be clean with no clipping .... while other HUs (like cheap BOSS units) can start clipping even before 75%. In an ideal world, you'd use an oscilloscope to look at the signal coming out of the HU, and you'd turn up the volume until the sine wave started to clip the peaks off ... then back it off a bit to restore the nice sine on it. This would be the max volume it's capable of without clipping. Your 2600NEX should be pretty good about not clipping at the upper range. You could probably go up to 80 or even 90% of volume on it. Just know wherever you set the volume for gain settings will become the max amount you should ever turn the system to.

So in lieu of having an o-scope, using 75% on the HU is a safe spec to use in most scenarios. For the DSP, I would turn it out to 100% ... unless you never plan to turn it to max ... then set it to the maximum level you would ever use on it. I don't think the TwK-88 will cause clipping at 100% volume, assuming the input is clean ... as it should onyl allow a signal up to the limit of the input, and the volume is an attenuation of the input signal ... but I'm not sure as I've never researched that DSP.

In my system, I don't use the volume of my DSP (Helix v-eight) and only use my HU's volume. But my setup is a bit different, and my preferences may be different as well.

The process you outlined looks good. Be sure to disable all crossovers as well (HP and LP filters), as these will cause weird things to happen when you're trying to measure VAC on the amp terminals. Just be sure to re-enable them before hooking the speakers back up.
 

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Discussion Starter · #44 ·
So the RCA voltage specs are max voltage. The voltage output of an RCA is variable, dependent on the volume level being played. The typical approach is to set the volume stages (HU and DSP) to the max level you would ever turn them to, or ... to the max level where clipping would start, and then set the gain/sensitivity of the amps based on that. So you get maximum clean output from the amp (up to the limit of the speakers connected of course) without introducing any clipping. If you then need to adjust gains to balance different speakers, you would only reduce the gains from this point, but never increase them.

The 75% recommendation for the head unit volume is a general rule-of-thumb, which assumes there's no clipping of the signal from the HU at 75%. Some head units (like my 80PRS) can go to 100% volume and still be clean with no clipping .... while other HUs (like cheap BOSS units) can start clipping even before 75%. In an ideal world, you'd use an oscilloscope to look at the signal coming out of the HU, and you'd turn up the volume until the sine wave started to clip the peaks off ... then back it off a bit to restore the nice sine on it. This would be the max volume it's capable of without clipping. Your 2600NEX should be pretty good about not clipping at the upper range. You could probably go up to 80 or even 90% of volume on it. Just know wherever you set the volume for gain settings will become the max amount you should ever turn the system to.

So in lieu of having an o-scope, using 75% on the HU is a safe spec to use in most scenarios. For the DSP, I would turn it out to 100% ... unless you never plan to turn it to max ... then set it to the maximum level you would ever use on it. I don't think the TwK-88 will cause clipping at 100% volume, assuming the input is clean ... as it should onyl allow a signal up to the limit of the input, and the volume is an attenuation of the input signal ... but I'm not sure as I've never researched that DSP.

In my system, I don't use the volume of my DSP (Helix v-eight) and only use my HU's volume. But my setup is a bit different, and my preferences may be different as well.

The process you outlined looks good. Be sure to disable all crossovers as well (HP and LP filters), as these will cause weird things to happen when you're trying to measure VAC on the amp terminals. Just be sure to re-enable them before hooking the speakers back up.
Ahhh, okay, this makes a lot of sense, thank you.

I like using the DSPs volume control. The HU, while excellent, has the worst volume interface (tiny buttons in the bottom corner that you can't adjust unless music is actively playing, so you forget to turn it down before you turn your car off? It's going to blast you). The DSP has a nice two-knob remote for overall volume and sub volume, and I love it.
Crossovers, got it, didn't think of that, either.

Okay, this sounds like a plan. So this is just to make sure the baselines are all matching and everything is optimized out the gate, then afterwards start addressing the problems in the system, correct? Like no expectation that this alone is going to solve the lack of bass problem that I'm having.
 

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Exactly. This process will setup the gain structures, to give you that solid foundation to tune off of. You can leave the TA settings in place for this.

If you want to use the DSP volume control only, I'd set the HU volume at 80%, and then just leave it there, and turn the DSP volume to 100% for gain setting.

Once you have the gains set, re-enable the crossovers but keep any EQ flat. hook up the speakers, and play pink noise while watcjing the RTA graph in real-time. I find it helpful to reduce the average in REW to 4 samples when doing this, so it's faster to see the impacts of changes. Now use the gains on the amps (only reducing them, never increasing) to make any adjustments needed to get the curve as close as possible to the target.

So if after setting gains, the highs are way too loud, as seen on the RTA graph ... turn down the gain on the amp for the channels feeding the tweeters, until that part of the RTA graph is as close as you can get it to the target curve.

So in this step, you're matching the output to the target using the gains, instead of trying to EQ a bunch of frequency bands, or messing with the trims in the DSP. It makes EQ'ing and individual speaker level matching much easier in later steps.
 

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Edit: just saw what i said was mentioned just in a different way. But I would make sure any effects or eq or any other sound settings are flat or just turned off as well.
 

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Discussion Starter · #47 ·
Exactly. This process will setup the gain structures, to give you that solid foundation to tune off of. You can leave the TA settings in place for this.

If you want to use the DSP volume control only, I'd set the HU volume at 80%, and then just leave it there, and turn the DSP volume to 100% for gain setting.

Once you have the gains set, re-enable the crossovers but keep any EQ flat. hook up the speakers, and play pink noise while watcjing the RTA graph in real-time. I find it helpful to reduce the average in REW to 4 samples when doing this, so it's faster to see the impacts of changes. Now use the gains on the amps (only reducing them, never increasing) to make any adjustments needed to get the curve as close as possible to the target.

So if after setting gains, the highs are way too loud, as seen on the RTA graph ... turn down the gain on the amp for the channels feeding the tweeters, until that part of the RTA graph is as close as you can get it to the target curve.

So in this step, you're matching the output to the target using the gains, instead of trying to EQ a bunch of frequency bands, or messing with the trims in the DSP. It makes EQ'ing and individual speaker level matching much easier in later steps.
Truly wiping the slate and starting clean with everything.

Okay, HU 80%, DSP max volume. Set the gains with MM. Reconnect, re-enable crossovers, use RTA with samples of 4 and use gain control to get the general curve set, then set the EQ and trim levels for finesse control.

It's going to be a fun evening 😆
 
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Discussion Starter · #48 ·
Edit: just saw what i said was mentioned just in a different way. But I would make sure any effects or eq or any other sound settings are flat or just turned off as well.
The input controls that I see are here:

Light Font Screenshot Biome Software


Are you referring to the top right section?

Font Screenshot Software Technology Electronic device


The HU is already 4V, the TwK 4V (I believe).
 

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Truly wiping the slate and starting clean with everything.

Okay, HU 80%, DSP max volume. Set the gains with MM. Reconnect, re-enable crossovers, use RTA with samples of 4 and use gain control to get the general curve set, then set the EQ and trim levels for finesse control.

It's going to be a fun evening 😆
Ya, that's what I would do. Especially after seeing how low the sub curve was compared to the mid/high curve in your last graph. It made me think the gains weren't set properly, and then your response kind of confirmed it.

If the gains are off, you can chase your tail quite a bit ... and then you're always left wondering if you have a gain issue or not. So doing this will ensure your gains are optimized (as much as you can with the tools you have), and eliminate it as a point of issue.

In terms of the input sensitivity of the TwK-88 ... ophidia is right, in that it should be optimized for the output signal from the HU.

Here's the specs on the TwK-88:

Rectangle Font Screenshot Parallel Number


It looks like the input sensitivity can be adjusted between 250mv to 7.1v. If your HU is going to be set at 80%, and it's spec is rated at 4v ... then 80% is probably putting out 3v maybe? You can test this too, by disconnecting an RCA from the TwK-88's input, and reading it with a meter set to VAC when playing a test tone. Just be really careful not to short the ground and center pin of the RCA cable with the meter lead. If it reads say 3v, then you can up the input sensitivity of the TwK-88 to match for 3v, instead of 4v. Just know that 80% on the HU volume would the be the max you would ever go with it.

Note: Pioneer HU's can be really picky about hot swapping RCAs ... so don't connect/disconnect the RCA cable between the HU and the TwK-88 while the system is powered up. Only do this when the system is off.
 

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Discussion Starter · #50 ·
Ya, that's what I would do. Especially after seeing how low the sub curve was compared to the mid/high curve in your last graph. It made me think the gains weren't set properly, and then your response kind of confirmed it.

If the gains are off, you can chase your tail quite a bit ... and then you're always left wondering if you have a gain issue or not. So doing this will ensure your gains are optimized (as much as you can with the tools you have), and eliminate it as a point of issue.

In terms of the input sensitivity of the TwK-88 ... ophidia is right, in that it should be optimized for the output signal from the HU.

Here's the specs on the TwK-88:

View attachment 313559

It looks like the input sensitivity can be adjusted between 250mv to 7.1v. If your HU is going to be set at 80%, and it's spec is rated at 4v ... then 80% is probably putting out 3v maybe? You can test this too, by disconnecting an RCA from the TwK-88's input, and reading it with a meter set to VAC when playing a test tone. Just be really careful not to short the ground and center pin of the RCA cable with the meter lead. If it reads say 3v, then you can up the input sensitivity of the TwK-88 to match for 3v, instead of 4v. Just know that 80% on the HU volume would the be the max you would ever go with it.

Note: Pioneer HU's can be really picky about hot swapping RCAs ... so don't connect/disconnect the RCA cable between the HU and the TwK-88 while the system is powered up. Only do this when the system is off.
Sooooo, if I were to short the pins or hot swap the RCAs while powered on, what could happen...?
 

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Discussion Starter · #51 ·
It looks like the input sensitivity can be adjusted between 250mv to 7.1v. If your HU is going to be set at 80%, and it's spec is rated at 4v ... then 80% is probably putting out 3v maybe? You can test this too, by disconnecting an RCA from the TwK-88's input, and reading it with a meter set to VAC when playing a test tone. Just be really careful not to short the ground and center pin of the RCA cable with the meter lead. If it reads say 3v, then you can up the input sensitivity of the TwK-88 to match for 3v, instead of 4v. Just know that 80% on the HU volume would the be the max you would ever go with it.
I FOUND IT!!!

Light Font Screenshot Biome Line


I had no idea you could do this! I'm curious now, what has this been doing since I've had this grossly mismatched?!!
 

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Discussion Starter · #52 ·
These are my options:

Font Communication Device Gadget Screenshot Electronic device
 

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Sooooo, if I were to short the pins or hot swap the RCAs while powered on, what could happen...?
You risk damaging the HU. This was a serious concern with the older HUs (like my 80PRS)... maybe Pioneer has resolved it in the newer units (like your NEX), but better be safe than sorry.

I FOUND IT!!!

View attachment 313560

I had no idea you could do this! I'm curious now, what has this been doing since I've had this grossly mismatched?!!
Nice! Having it set for 1.0v would cause the signal to be too hot in the DSP, since the HU is sending out up to 4v; depending on volume setting.

I'd set it for 4.0v, or 2.8v ... depending on where you plan to keep the HU volume. If you plan to set it to 80% and just leave it there, 2.8v may work well. Measuring the VAC on the RCA from the HU will guide this though.
 

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Discussion Starter · #54 ·
You risk damaging the HU. This was a serious concern with the older HUs (like my 80PRS)... maybe Pioneer has resolved it in the newer units (like your NEX), but better be safe than sorry.



Nice! Having it set for 1.0v would cause the signal to be too hot in the DSP, since the HU is sending out up to 4v; depending on volume setting.

I'd set it for 4.0v, or 2.8v ... depending on where you plan to keep the HU volume. If you plan to set it to 80% and just leave it there, 2.8v may work well. Measuring the VAC on the RCA from the HU will guide this though.
Ahhhhhhh. Well, I'm not sure I was paying attention to that before, but I certainly will now.

Just to be sure, although it's a fairly elementary question, when testing the voltage on an RCA cable am I touching one lead to the center pin and the other to the shroud, or lead to pin and other lead to an external ground?

Also, I need to see where I have them, but the little speaker enclosures I have for my 5.25s, I was getting some conflicting info where one recommendation was to seal them completely and the other was to leave a vent for the speaker to breathe, so I never installed the wire grommets or sealed around the grommets. For that midbass would it be better to go ahead and seal them up?
 

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Discussion Starter · #55 ·
Edit: just saw what i said was mentioned just in a different way. But I would make sure any effects or eq or any other sound settings are flat or just turned off as well.
Sorry, just saw this. Yes, at the HU I have every bit of signal processing turned off, and when I start testing I'll nix all the stuff happening at the DSP.
 

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Ahhhhhhh. Well, I'm not sure I was paying attention to that before, but I certainly will now.

Just to be sure, although it's a fairly elementary question, when testing the voltage on an RCA cable am I touching one lead to the center pin and the other to the shroud, or lead to pin and other lead to an external ground?
One lead to the center pin on the RCA, the 2nd lead to the outer shroud on the RCA, not an external ground. It can be helpful to grab an RCA coupler, and plug it onto the end of the cable. So you can stick one of the meter leads inside a hole, and not risk shorting to the shroud.

Also, I need to see where I have them, but the little speaker enclosures I have for my 5.25s, I was getting some conflicting info where one recommendation was to seal them completely and the other was to leave a vent for the speaker to breathe, so I never installed the wire grommets or sealed around the grommets. For that midbass would it be better to go ahead and seal them up?
I would try them sealed myself ... but it can be modeled in WinISD, if you have the little enclosure volume spec and the T/S parameters of the speakers. Or, you can seal one of them and take near field measurements on both. Compare the sealed to the non sealed, and see the difference.
 

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Discussion Starter · #57 ·
One lead to the center pin on the RCA, the 2nd lead to the outer shroud on the RCA, not an external ground. It can be helpful to grab an RCA coupler, and plug it onto the end of the cable. So you can stick one of the meter leads inside a hole, and not risk shorting to the shroud.



I would try them sealed myself ... but it can be modeled in WinISD, if you have the little enclosure volume spec and the T/S parameters of the speakers. Or, you can seal one of them and take near field measurements on both. Compare the sealed to the non sealed, and see the difference.
No couplers on hand, so I guess the message is "Be very, stupidly careful." Can I get away with just testing one set or should I do all three?

Something I was thinking of, I have all three sets of RCA outputs from the HU plugged into my DSP, but it looks like I can just use one set from the HU and split the frequencies to all of the outputs. Is there any benefit to me having all three sets used if I don't use the HU for any processing? Right now I just use the HU to adjust speaker outputs or play with time delay on the fly to test things when I'm driving to later move to the DSP.

Sadly not enough specs on the enclosure to model. I pulled out WinISD and gave it a shot, realize I have zero dimensions. But, it was good to get the program running since learning the basics of that is a goal.
 

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No couplers on hand, so I guess the message is "Be very, stupidly careful." Can I get away with just testing one set or should I do all three?
You can just test one RCA cable ... you don't even need to test a pair, but just one will do.

Something I was thinking of, I have all three sets of RCA outputs from the HU plugged into my DSP, but it looks like I can just use one set from the HU and split the frequencies to all of the outputs. Is there any benefit to me having all three sets used if I don't use the HU for any processing? Right now I just use the HU to adjust speaker outputs or play with time delay on the fly to test things when I'm driving to later move to the DSP.
Using all 3 sets just enables you to still use the head unit controls, and that's really it. You could use only one or two sets if you wanted to, assuming a full range signal is present on it.

I checked this on my 80PRS, as I'm also using 3 sets of RCAs to my DSP. The Helix has a screen where I can see thr frequency response of the incoming signal, and when I ran it against my front RCAs .. it was cut off somewhere around 80Hz. This made me think the 80PRS HU isn't sending sub frequencies out of the front and rear RCA outputs even when I had all crossovers byassed in the HU. I didn't do much more investigating on it though, since I have all 3 RCA pairs run to the DSP.

Here is how my system is setup:

Product Rectangle Font Parallel Diagram


Sadly not enough specs on the enclosure to model. I pulled out WinISD and gave it a shot, realize I have zero dimensions. But, it was good to get the program running since learning the basics of that is a goal.
Ya, that's kind of what I figured. You can just seal one and see how it registers on a near field measurement. Removing the seal should be easy enough, right?
 

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Discussion Starter · #59 ·
You can just test one RCA cable ... you don't even need to test a pair, but just one will do.

Using all 3 sets just enables you to still use the head unit controls, and that's really it. You could use only one or two sets if you wanted to, assuming a full range signal is present on it.

I checked this on my 80PRS, as I'm also using 3 sets of RCAs to my DSP. The Helix has a screen where I can see thr frequency response of the incoming signal, and when I ran it against my front RCAs .. it was cut off somewhere around 80Hz. This made me think the 80PRS HU isn't sending sub frequencies out of the front and rear RCA outputs even when I had all crossovers byassed in the HU. I didn't do much more investigating on it though, since I have all 3 RCA pairs run to the DSP.

Here is how my system is setup:

Ya, that's kind of what I figured. You can just seal one and see how it registers on a near field measurement. Removing the seal should be easy enough, right?
Awesome, I'll just do the one, then.

That's what I figured, just to preserve the HU controls. It's handy when I need it, but I could benefit off not having as many RCAs running around the cabin. It's a rat's nest already. My install is temporary while I figure out where I want everything, and I'm still not sure yet.

That's pretty much the same configuration as mine. Oh, on my 2600 if it's in networking mode (high/mid/sub instead of front/rear/sub) there's a HPF on the highs even if I don't want it. You can turn the HPF/LPFs off the mids and subs, but highs is locked at a 1.25 kHz cross with -6 dB.

Removing the grommet should be easy enough, but the instructions with the enclosure recommend caulking the grommet after installation, so I didn't want to do all of that. Should be easy enough to just test the grommets, if I can just remember where I left them.....
 

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That's pretty much the same configuration as mine. Oh, on my 2600 if it's in networking mode (high/mid/sub instead of front/rear/sub) there's a HPF on the highs even if I don't want it. You can turn the HPF/LPFs off the mids and subs, but highs is locked at a 1.25 kHz cross with -6 dB.
With the DSP, you should be running the HU in "standard" mode, and not "Network" mode ... in case you aren't already. That 1.25k @ 6dB high pass is there as a protection for the tweeters, since in Network Mode, only tweeters would be connected to those channels.

I ran mine in Network mode for years, and only recently switched it over to Standard after installing the Helix DSP.

For my routing, I have the front signals splitting to the mids and the tweeters in the DSP, and I have the rear signal going to my rear fills. And of course, sub to sub.

I did it this way so I could maintain fade/balance control at the HU, but after installing the Conductor remote control for the Helix (which allows for rear channel attenuation), I really don't need the fade controls in the HU afterall. My install is already finalized though, will all cables neatly tucked and ran through the car; so I didn't see a reason to not use all 3 pairs of RCAs. If you are still planning the final run of cables ... and the 2600NEX has a full range signal on one set of RCAs ... then you could absolutely get away with just running one pair from the HU to the DSP (y)
 
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