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-   -   Tutorial: Dual sub integration using the MiniDSP (http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1488457-tutorial-dual-sub-integration-using-minidsp.html)

neutro 08-30-2013 02:01 PM

Dual sub integration using the MiniDSP

The goal of this thread is to discuss a handful of topics regarding the integration of one or more subwoofer, using a MiniDSP 2x4, to your average home theater setup. While the MiniDSP is a great platform to perform subwoofer equalization, this won't be discussed here in detail. Rather, I want to focus on how to:

  • Perform the actual connexions and setup of the MiniDSP and subs in the system
  • Use the MiniDSP as a splitter to simplify the setup for multiple subwoofers
  • Easily level-match multiple subs using the MiniDSP
  • Tweak the sub integration with the mains using the MiniDSP
  • Add a house curve on top of whatever EQing is performed by the AVR

Edit: Here's a pretty good tutorial hosted by MiniDSP for EQing subs using REW for readers more interested into EQing. Thanks to @McStyvie for pointing it out!


Gear

The required gear for this tutorial is simply:

  • An AVR
  • Up to four subwoofers
  • An appropriate number of subwoofer cables
  • A MiniDSP 2x4
  • A MiniDSP plugin

The basic MiniDSP 2x4 is sufficient for the job but of course, other models can also be used, which would allow for integrating even more subwoofers. Many MiniDSP plugins can also do the job; basically the following plugins have all the required blocks and can also be used to EQ the subs to boot:

  • 2-way Advanced Crossover
  • 2.1-way Advanced Crossover
  • 3 or 4-way Advanced Crossover
  • 2x8, 4x10 and 10x10 Crossover

Note that the sub channel in the 2.1-way Advanced Crossover plugin would not be used. This is because the MiniDSP platform can be used as a digital crossover for mains, hence why it has two inputs and four outputs. We won't use the MiniDSP that way, and thus simply require one output per sub. This means that a single MiniDSP 2x4 can be used to level-match and delay-adjust up to four subs, provided a splitter is used to feed the subwoofer channel to the two inputs. In the rest of this tutorial, I will use the 2-way Advanced Crossover. Note that upon buying a plugin, MiniDSP will send a download link via email: the plugin is not factory-installed on the MiniDSP itself.

Setup

The physical setup depends on the AVR capabilities and, of course, the number of subwoofers. In all case though, connections are fairly simple.

Powering the MiniDSP

The MiniDSP can be powered via USB or using the DC Phoenix-type block connector on the back. Once included in the setup, it has to be powered for the subs to get any signal. USB power can come from a computer or a standard phone charger. DC power can come from just about any wall-wart type power supply capable of 4.5 to 24 V. If used, the terminal from the DC power supply should be cut and bare wires inserted in the Phoenix connector using the correct polarity. Failure to use the correct polarity will probably damage the MiniDSP. Note that in my experience, connecting and disconnecting the USB cable (thus powering on and off the MiniDSP if the back connectors are unused) does not lead to any loud pops and is thus safe to do with the subs turned on.

Connecting a single subwoofer

Connecting a single subwoofer to the MiniDSP is as simple as it gets. The MiniDSP sits between the AVR and subwoofer as in the figure below, with the AVR's sub pre out being fed to Input 1 on the MiniDSP, and Output 1 of the MiniDSP linked to the line level input of the subwoofer:



Connecting two subwoofers

Assuming the AVR in the setup has a single sub pre out, connecting a second subwoofer simply involves plugging it into Output 2 of the MiniDSP as in the figure below. The MiniDSP thus acts as a splitter.



If the AVR in the setup has two sub pre outs, but cannot distinguish between individual subs (i.e. the two outputs are just part of an internal splitter), then the easiest way to integrate the MiniDSP is still to only use one of the AVR's two subwoofer outputs and let the MiniDSP assume the role of splitter.

However, if the AVR can distinguish between individual subs, as is the case with AVRs equipped with Audyssey SubEQ HT, then for it to be able to treat the subwoofers independently, it is required that each AVR sub pre out be connected to one input of the MiniDSP, as in the figure below. Using the 2-Way Advanced Crossover plugin, Input 1 of the MiniDSP will be linked to Outputs 1 and 2, while Input 2 will be linked to Outputs 3 and 4. It is thus necessary to plug the second subwoofer to Output 3.



Connecting up to four subwoofers

Since the two inputs of the MiniDSP 2x4 are totally independent (for example, using the 2-Way Advanced Crossover plugin, there is no way to send signals from Input 1 to Outputs 3 and 4), it is necessary to use an external splitter before the MiniDSP (and thus using its two inputs) to connect more than two subwoofers on the MiniDSP, as illustrated below:



Connecting the MiniDSP to a computer

The MiniDSP can operate without being connected to a computer. However, configuration of the plugin must be done by plugging the MiniDSP to a computer via USB. During configuration, unless the MiniDSP is connected to a DC source, it will then be powered by the computer's USB port.

Plugin exploration

The plugin application can be started even if the MiniDSP is not connected to the computer, and can be safely explored this way. Even when the MiniDSP is connected to the computer via USB, no firmware will actually be loaded on the MiniDSP unless the green sync button on the top right is clicked. When started, the application should look like the screenshot below:



This tutorial is not meant as a complete tour of the 2-Way Advanced CrossoerPlugin and of MiniDSP applications, and thus, we will concentrate on the plugin's block diagram below the four tabs. Each yellow box is a clickable module in which parameters can be changed.

The plugin's architecture is quite clearly mapped in this block diagram. Both inputs share the Input Gain block, meaning they are affected by it simultaneously. Downstream from the Input Gain block, the two branches of the plugin don't cross again. In that regard, as mentioned before, the output pairs (1 and 2 vs 3 and 4) are completely independent with the 2-Way Advanced Crossover plugin. Using one or two subs, the bottom branch of the diagram will be completely unused, unless the AVR is SubEQ HT-equipped, in which case the two branches' independence becomes handy.

Downstream from the Input Gain block, there is a first Parametric EQ block in each branch. On the top branch, this block is common to Output 1 and Output 2; on the bottom branch, it is common to Output 3 and Output 4. Thus, any filter programmed in this block will simultaneously affect the connected outputs.

This is in contrast with the Parametric EQ blocks that are downstream from the Crossover block. These further PEQ blocks are specific each output. Finally, the Delay/Gain/RMS block is a single block, but can be used to adjust the gain, delay and polarity of each output independently. It can also be used to mute each sub independently using a single click.

Configuring the Crossover block

The first step to configuring the plugin is to click on the green Sync button and wait until the pluggin application is synced to the MiniDSP. When synced, any change to the plugin will be loaded and effective immediately on the MiniDSP.

Our first task will be to configure the Crossover blocks so that they act as a perfect splitters instead of the default crossover. This is essential to all subwoofer configuration since by default, unneeded low or high pass filters are applied by the Crossover blocks. Note that if Outputs 1 and 2 only are used, the second Crossover block need not be adjusted.

The internal structure of the 2-Way Crossover block is illustrated in the diagram below:



The block is thus a splitter, followed in each branch by a low-pass and a high-pass filter. By default, the upper branch has the high-pass filter enabled and the lower branch has the low-pass filter enabled.

Clicking on a Crossover block brings us to the 2-Way Crossover block menu. The lower part of the application, below the plugin's block diagram, is now split in two. On the left are the parameters for the four filters; on the right is a frequency response diagram for the block (the top and bottom outputs are in different colors).

Our goal is to bypass all filters in order to simply have a perfect splitter. First click on the "CH1 BandPass filter OUT1" button, and click on the two BYPASS buttons. Do the same after selecting the "CH1 BandPass fitler OUT2" button. Now the Crossover block should have no effect short of just splitting the signal, as illustrated in the screenshot below:



At this point, the signal from the AVR's sub pre out should be able to reach all subs without being affected by any filter in the path.

Level-matching multiple subs

(Note: AVRs equipped with SubEQ HT automatically level-match two subs; this step can thus be ignored in such setups. It can however be used in conjunction with SubEQ HT to level-match pairs of subs in setups with more than two subwoofers.)

When using multiple subwoofers, one of technique is to ensure that all units play test tones at the same level at the listening position. Typically this operation involve lots of fiddling with the sub's gains, which can be tiresome when controls are hard to reach or when subs are far apart. Ensuring that the combined output of multiple subs reach the right level can be equally equally tiresome. The MiniDSP and 2-Way Advanced Crossover plugin can be used to elegantly level-match all subs without having to fiddle with the subs' gains nor with any setting in the AVR.

The first step is to set the subwoofer gains (on the sub's amps) at a relatively high level -- the MiniDSP can only attenuate the signal it gets from the AVR. In my own case, this allows me to set the gain on the subwoofers to the maximum setting, as recommended by the manufacturer. All subs can be set to the same gain.

The second step is to click on the Delay/Gain/RMS block corresponding to the connected subs in the plugin application. The lower part of the application now displays level meters for the two outputs for that block, along with a few other controls. Note the very handy Mute buttons, in particular.

To level-match the subs, first mute all subs but one and start playing a calibration tone. For example, when starting Audyssey, it typically asks the user to set the subwoofer gain in order to get 75 dB, with the measured level displayed on the TV. While only one sub is playing, adjust the volume to 75 dB using the slider along the meter for the sub that is playing. Now repeat the operation for all sub, muting all others and adjusting the sliders so that they all produce 75 dB at the listening position.



Now all subs, individually, are set at the proper volume. Unmute all subs and click on the Input Gain block. The calibration tone should be much louder with all subwoofers playing. Note that if two subs playing together don't sound louder than a sub playing alone, there could be a driver polarity issue, with the subwoofers actually playing out of phase. Interestingly, the 2-Way Advanced Crossover plugin can be used to reverse the polarity of each output signal, using the "Invert" button in the Delay/Gain/RMS blocks.

The objective is now to lower the overall volume until the 75 dB target is achieved while keeping the same balance between the subs. This is easily done by clicking on the Input Gain block and lowering the gain slider until the target level is reached. Thus, each sub is individually set to 75 dB using the output gains, and the common input gain is used to adjust their combined level to 75 dB.

Tweaking delays

(Note: AVRs equipped with SubEQ HT automatically adjust the delays of up to two subs; this step can thus be ignored in such setups. It can however be used in conjunction with SubEQ HT to adjust delays of pairs of subs in setups with more than two subwoofers.)

Many AVRs will be able to adjust the delay of each channel, including the subwoofer, so that all sound waves arrive in synchrony at the main listening position. In particular, failing to correctly adjust the delay of the subwoofer channel may introduce cancellation between the mains and the subwoofer in the crossover frequency range. Verifying this require either a good hearing and lots of experienc, or more reliably, a frequency response measurement. Frequency response measurements are not covered in this tutorial, but can be performed rather easily using an Omnimic system, or using the free Room EQ Wizard (REW) software from HomeTheaterShack and one of the many available microphones or SPL meters fit for the job. MiniDSP's own UMIK-1 microphone is particularly well-suited for the job.

The best way to resolve dips in frequency response due to cancellation between subwoofers and mains is to use real-time analysis (RTA), which is available in REW. Once engaged while playing pink noise, the dip caused by cancellation can be lessened or even totally removed by tweaking the delay of each output in the plugin's Delay/Gain/RMS output blocks. Note that due to the nature of subwoofer frequencies' interaction with the room, substantial delay can be necessary to improve cancellation. The equivalent distance (obtained by dividing the speed of sound by the delay introduced, and displayed in the plugin controls) can be quite difference from the physical distance between the subwoofers and the listening position.

Introducing a house curve

AVRs equipped with subwoofer equalization capabilities such as Audyssey MultEQ XT and XT32 most often will only EQ the frequency response flat. While other technologies such as Audyssey DynamicEQ and THX Loudness Plus can alter the flatness of the equalization to introduce more bass at lower listening levels, sometimes user still prefer an additional oomph.

Most often, the subwoofer(s) will be ran "hot", meaning that either the gain of the subwoofer(s), or the AVR's subwoofer trim level, will be inched a few dBs higher to reflect that preference. While very simple to implement, the caveat is that the boost will affect equally all frequencies played by the subwoofer(s). The MiniDSP can be used to easily tweak the balance of those frequencies using the Parametric EQ blocks of its plugins.

Note that the Parametric EQ blocks are independent, and if more that two outputs of the MiniDSP are used, it may be required to copy the parameters from one block to another. This can be done manually, or in some cases using the Copy buttons in the Parametric EQ blocks. The Parametric EQ blocks upstream from the Crossover blocks can thus be made to quickly share the same parameters. The Parametric EQ blocks downstream from the Crossover block can also be copied in pairs: Output 1 with Output 3 and Output 2 with Output 4.

Each Parametric EQ block can introduce up to six biquadratic ("biquad") parametric filters. The frequency response of each block is conveniently displayed while adjusting the parameters, which can be entered either via the user interface, of by importing a text file (which itself can be generated by REW). The parameters can also be introduced by hand using the same syntax found in this text file using the "Advanced" interface, with the help of the Biquad Calculator tool provided in the plugin application under the tab of the same name.

Using Parametric EQ filters (PEQs) to flatten the frequency response can be tedious and is better left to software such as REW. However, tweaking a flat response to introduce a house curve can be done by adding a single PEQ to the setup, as done in the figure below:



In that example, dual subs are connected to Outputs 1 and 2. Thus, the Parametric EQ block upstream of the Crossover block is used to introduce the house curve, in order to simultaneously affect the two outputs. Filter EQ1 is selected -- this is the only filter having a non-zero gain. All filters having a zero gain are effectively bypassed, but each filter can be explicitly bypassed using the "BYPASS" button without changing their parameters.

The parameters are set as to provide a gently-rising house curve that gradually boosts the frequency response to reach +6 dB at 20 Hz. Note that this provide substantial reinforcement of the deep rumbles produced by sub-audible frequencies. To achieve this, a low-shelf filter type has been selected, with a 40 Hz corner frequency, a gain of 8 dB and a Q-factor of 0.5. Those parameters can be adjusted on-the-fly in any situation (including when watching a movie or music), and the effect of the filter on the frequency response can be seen instantaneously. It is thus easy to adjust the shape of the house curve even with limited knowledge of what each parameter will do. Moreover, it is very useful to develop an intuition about what the parameters actually mean.

Another type of house curve that is easy to introduce is a peak filter type. Introducing peaks around 60 or 80 Hz, with substantial gain, one can significantly enhance the "chest thump" or "slam" that a subwoofer will produce. Experimenting with the frequency, gain and Q-factor of single peak filters can help understand where such effects come from. Such filters can easily be bypassed later if a flatter response is preferred.

Saving

While all changes will be loaded immediately on the MiniDSP while the plugin is in sync with the device, it can be useful to save a configuration for later retrieval. This can be done in the System Settings tab. Configurations are saved on your computer as a standalone file that can be loaded again at anytime.

basshead81 08-30-2013 02:32 PM

Sticky worthy!

landshark1 08-30-2013 02:46 PM

Thanks for the excellent detail write up!!

pdxrealtor 08-30-2013 02:52 PM

Wow! Nice work...

I haven't read it yet, but it looks great! This should be a sticky!

Spanglo 08-30-2013 02:56 PM

Wow it's that easy eh?

Many thanks for taking the time to explain the process neutro. This is sticky worthy.

NewHTbuyer 08-30-2013 03:40 PM

Awesome...thanks for the write up!

JackOften 08-30-2013 05:38 PM

Thanks! My 2x4 coincidentally arrived today. Looking forward to eq'ing my ULS dual drive.

06GTOguy 08-30-2013 06:36 PM

Subscribed!! Nice job

dominguez1 08-30-2013 09:11 PM

Wow. Great job! That took a lot of time!

 

Are you planning to do another tutorial on how to EQ? That would be very helpful! Specifically, how to EQ below 20hz...


mp5475 08-30-2013 10:23 PM

Nice job. I tried my minidsp on my three xv15s and xv30f today. Only messed with para. I actually liked the sound with out it. But after reading you excellent write up, I am going to try again. And add a house curve.

spidey.joe80 08-31-2013 02:34 AM

i want one!

neutro 08-31-2013 11:10 AM

Quote:
Originally Posted by Spanglo View Post

Wow it's that easy eh?

I think so smile.gif I thought I'd fall in a trap or something, but it was pretty straightforward. I think the most "difficult" part was to realize how to disable the crossover filters to just get a splitter.
Quote:
Originally Posted by dominguez1 View Post

Are you planning to do another tutorial on how to EQ? That would be very helpful! Specifically, how to EQ below 20hz...

Well, I bought a MiniDSP as a replacement for a BFD. It's much easier to use for sure (I kept forgetting how to overwrite parametric filters on the BFD).

However I ended up buying an Audyssey-equipped receiver just after, and so far I'm letting it EQ the subs (to a flat response). Since I already had the MiniDSP and I wanted to try it, I ended up integrating it anyway, and found it quite useful to level-match and tweak delays, hence the tutorial. So short of the house curve, I actually haven't tried EQing yet. It doesn't look too complicated with REW. REW will only generate the parameters for 6 PEQs, so they can be entered in a single Paramteric EQ block. The only thing to remember is that if the PEQ block used is downstream of the Crossover block, it may have to be copied manually to the block in the other branch. For this reason, I guess it's always easier to use the PEQ block upstream of the Crossover block.

Also, don't forget to disable the PEQ blocks when running Audyssey -- assuming that you want to use the MiniDSP to tweak Audyssey's results, you don't want Audyssey trying to fight the PEQs on the MiniDSP.

***

BTW, sorry if I don't follow this threads in the following day. A new baby* is on the way biggrin.gif

* A literal baby, not a new sub.

mp5475 08-31-2013 11:52 AM

Quote:
Originally Posted by neutro View Post

I think so smile.gif I thought I'd fall in a trap or something, but it was pretty straightforward. I think the most "difficult" part was to realize how to disable the crossover filters to just get a splitter.
Well, I bought a MiniDSP as a replacement for a BFD. It's much easier to use for sure (I kept forgetting how to overwrite parametric filters on the BFD).

However I ended up buying an Audyssey-equipped receiver just after, and so far I'm letting it EQ the subs (to a flat response). Since I already had the MiniDSP and I wanted to try it, I ended up integrating it anyway, and found it quite useful to level-match and tweak delays, hence the tutorial. So short of the house curve, I actually haven't tried EQing yet. It doesn't look too complicated with REW. REW will only generate the parameters for 6 PEQs, so they can be entered in a single Paramteric EQ block. The only thing to remember is that if the PEQ block used is downstream of the Crossover block, it may have to be copied manually to the block in the other branch. For this reason, I guess it's always easier to use the PEQ block upstream of the Crossover block.

Also, don't forget to disable the PEQ blocks when running Audyssey -- assuming that you want to use the MiniDSP to tweak Audyssey's results, you don't want Audyssey trying to fight the PEQs on the MiniDSP.

***

BTW, sorry if I don't follow this threads in the following day. A new baby* is on the way biggrin.gif

* A literal baby, not a new sub.

Congrats!

mp5475 08-31-2013 12:32 PM

Neutro, did you do delay after audyssey?

how did you figure the distance out?

did you add it to the distance from audyssey?

neutro 08-31-2013 01:15 PM

As far as I know, Audyssey doesn't try to blend the mains and sub as best as possible. It only measures the actual distance with time-of-flight from the sound pulses. In my case this introduced a sizeable dip in the crossover region.

I don't know if there is a general method to adjust delays in case of multiple sub to yield optimal results. You also have to realize that cancellation can occur from any of your 5 or 7 speakers, and that the ideal delay to apply to subs could be different for each of those. Typically we use the main left and right speakers, but arguably the center channel could be the best reference to adjust delays.

I for one played with the delays of both subs while using the RTA capabilities of REW to find a setting with a much shallower dip. It looks like the dip is reduced even if I move the measurement mic around the main listening position, so it seems "stable". I had to add a few effective feet to the sub distances in the process; but I couldn't tell you what the method was. It's basically trial and error; but with real time analysis of the results, the feedback loop is much faster to adjust the delays.

The crossover dip is still there though, just not as pronounced as before. I think it's there in most setup, and it's dependent on so many variables (main channel used, position of the mic, delays applied by the AVR, difference in delays in both subs, etc.) that I don't think it's advisable to obsess over that biggrin.gif

mp5475 08-31-2013 01:59 PM

Thx for the infi

braveheart123 08-31-2013 02:09 PM

Quote:
As far as I know, Audyssey doesn't try to blend the mains and sub as best as possible. It only measures the actual distance with time-of-flight from the sound pulses.

+1.......Audyssey only measures the -3dB roll off point of all the speakers and reports back to AVR apart from other parameters. AVR sets the crossover point based on the info returned by audyssey. But this method is very flawed, it always sets the mains to Large if they are towers. Most towers have -3dB point below 40Hz, which is good for music but not enough for movies.

Spanglo 08-31-2013 05:41 PM

Quote:
Originally Posted by neutro View Post

I think so smile.gif I thought I'd fall in a trap or something, but it was pretty straightforward. I think the most "difficult" part was to realize how to disable the crossover filters to just get a splitter.

***

BTW, sorry if I don't follow this threads in the following day. A new baby* is on the way biggrin.gif

* A literal baby, not a new sub.

Congrats for the new baby!

I guess I had it in my head that MiniDSP required a learning curve similar to REW. I have REW pretty well figured out by this point, and your process made MiniDSP sound refreshingly easy to config, so I think I'm good to go now.

The plan is to integrate a pair of sealed Dayton 18's, have them play flat to 10 Hz at about 85 dB with a house curve, and also with a pair of SB12's in the mix. So I'll be EQ'ing 4 subs individually to the house target curve, based on the average response of a few different couches.

rhed 08-31-2013 10:53 PM

Can the subsonic filters be set to desired setting in the plugin?

mp5475 09-01-2013 01:39 PM

Neutro, you ave PSA subs? Right?

So when you were level matching the subs with dsp, you put the sub gain at max?

basshead81 09-01-2013 09:41 PM

Quote:
Originally Posted by mp5475 View Post

Neutro, you ave PSA subs? Right?

So when you were level matching the subs with dsp, you put the sub gain at max?

I believe hes has Dual PC12+

neutro 09-02-2013 09:43 AM

Quote:
Originally Posted by Spanglo View Post

Congrats for the new baby!

Thanks -- telegraph style, I just got home with the baby & mother smile.gif It's a healthy 8 lbs 5 oz boy biggrin.gif

Good luck with the quads, please report back!
Quote:
Originally Posted by rhed View Post

Can the subsonic filters be set to desired setting in the plugin?

All PEQs can be set down to 10 Hz with the MiniDSP using the plugin application.
Quote:
Originally Posted by mp5475 View Post

Neutro, you ave PSA subs? Right?
Quote:
Originally Posted by basshead81 View Post

I believe hes has Dual PC12+

Basshead81 is right. Ed Mullen from SVS advised that the max peak performance with the 800W and 1000W Sledge amps are obtained setting the gain to 0dB (max setting). On one hand this is only relevant if pushing the subs close to their limits, which I think I'm far from doing even with the house curve and playing at reference level. On the other hand, for the obsessive-compulsive mind, it just feels right to have the recommended setting for max performance. The only problem is, in my room and with my AVR, I can't set the sub pre out level low enough to set both subs to the max gain. Also, how do you set the subs both to max gain if the level-matching step says you're supposed to have one 3 dB lower than the other? The MiniDSP allows that for me, which is neat I think.

neutro 09-05-2013 07:08 PM

By the way, Tony Rouget from MiniDSP contacted me and he put the tutorial on MiniDSP's own blog. Scroll toward the bottom to see it; however it's the same content as above, and the interesting bit is that the blogs links to other tutorials and made me notice the documents section of the site, where there are even more.

Spanglo 09-07-2013 07:29 PM

^ further confirmation of a job well done.

neutro 09-07-2013 08:30 PM

Thanks Spanglo...

Now with the newborn kid almost always close to the living room, we find ourselves listening to lots of music but at very soft levels (say, -50 dB).

At this level the subs fail to auto-turn-on most of the time, and when they do turn on (say, starting at a higher level), they auto-turn-off after a while at the reduced listening level.

So I think running the subs at their max gain is not possible for me. I'll try turning the gain down to -10 dB on both subs, and compensating by raising the input gain by 10 dB on the MiniDSP. I hope 10 dB is enough to wake up the subs...

Spanglo 09-07-2013 08:47 PM

That's an interesting problem that I never heard before.

Are headphones out of the question so you don't have to reconfigure?

neutro 09-07-2013 08:48 PM

So the settings I had previously were:

Output 1: -14 dB
Output 2: -17 dB
Input: -4.5 dB

... meaning that with the subs at max gain, I had to set them at -14 and -17 dB respectively to reach 75 dB at the listening position using each sub alone. Playing them together added 4.5 dB and thus the Input gain was set to -4.5 dB.

Now I wanted to reduce the gain on the subs by 10 dB and boost the signal reaching the subs by the same value. This was not possible to add 10 dB using the common input gain. Nor was it the correct way to do things according to the methodology outlined in the tutorial above; so I let the input gain to -4.5 dB and modified the output gains.

Now the settings are:

Output 1: -4 dB
Output 2: -7 dB
Input: -4.5 dB

And both subs are -10 dB. Now the subs auto turn on at about -55 dB but it depends on the content. Maybe I should just leave the subs on and not worry about auto-on biggrin.gif

neutro 09-07-2013 08:53 PM

Quote:
Originally Posted by Spanglo View Post

That's an interesting problem that I never heard before.

This is due to me having two overkill subs in a small room. They require very little power each to achieve 75 dB at the listening position. Normally I should adjust the gains way lower on the subs. I was trying to set them to the max but in the end, we listen to the setup at -55 dB way more often than at -5 dB, so I'm happy now smile.gif
Quote:
Are headphones out of the question so you don't have to reconfigure?

Well headphones have notable disadvantages:

  • It's awkward sharing headphones when many people want to listen to music
  • The baby can't get used to bass
  • In the end I prefer the feeling of bass from subs, even at lower volumes.

blah450 09-30-2013 05:04 AM

Hello. Neutro suggested I post a finding about the miniDSP and the plug-in combos below....

I am running a single sub pre-out unbalanced RCA signal from my AVR to a miniDSP 2x4 balanced kit which feeds two EP4000 amps which drive four DA 18" subs.

I flashed 4-way Advanced plug-in to DSP and it was able to turn a single input into four equal outs. Perfect for those folks wanting to run miniDSP with 3-4 subs?

I then flashed 2-Way Advanced back to same DSP and everything functioned fine, albeit with the different plug-in looking for 2 inputs in order to output 3-4 channels. This plug-in can NOT take a single output and split to four outputs, only to two outputs. One input gets two outs max using this plug-in scenario.

Lastly, flashed 4-Way Advanced plug-in back to same DSP one last time and all looked good. I left it as such because the 4-Way Advanced Plug-in serves my purposes a little better with four identical subs.

(as an aside, with regard to the .9V and 2V input jumpers, the miniDSP Team suggested checking the actual level of the input and then adjust the jumpers accordingly).

pdxrealtor 09-30-2013 10:58 AM

Did you try running a splitter to create two sub input ?


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