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post #61 of 123 Old 05-28-2020, 05:12 PM - Thread Starter
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Originally Posted by neo_2009 View Post
Have you read the dbx PA2 manual?
They detail a procedure to "... manually optimizing the system’s gain structure ..."

Please see section: 3. Set Gain Structure & Limiters, page 19.

Maybe it has some information to overcome the hiss.

Regarding the Software, does it have any option to control the input gain?

On the Monacor Software, this option is available, i would assume it should be possible on the DBX?
Yes I have read the documentation.

Yeah the Mini has the same input gain sliders, on the PA2 you would have to go into the compressor, which is kind of odd and not quite right IMO.

This is designed to be use with a Mixer before the PA2 so they assume you are doing input gains there...

Reading into hiss etc on a number of other sites seem to indicate its usually some kind of mismatch between output impedance and input impedance on the Emotiva amps, not exactly the input gain itself. that would make sense why some people get zero noise vs others.
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post #62 of 123 Old 05-28-2020, 06:54 PM
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Quote:
Originally Posted by Javs View Post
Like I said, tried everything. If MUTE does not change the hiss, nothing will. Ive experienced this with the MiniDSP. I definitely know how to setup the input gain structure on a DSP, this unit is actually even more simple than something like a MiniDSP, I have even used oscilloscopes to do it to measure when the preamp starts distorting the sinewave, but we are not even against that wall, this is literally just the noise floor of the DSP paired with my Emo amp.

And yes, there is no proper input gain setting, you have to use the limiter function, which I think is odd personally. But it is what it is.

Its a bit frustrating that the channels are linked like they are on the PA2.

Need to buy attenuators... Now the question is, should I get 10, 15 or 20db attenuators.

I have 12db attenutators on the MiniDSP outputs and they are much more quiet only a couple db over the amps raw noise floor.
I use balanced connection on MiniDSP 10x10HD, Crown XLS Drivecore 2 amps using XLR from Marantz AV7703 and I do not have a hiss problem with direct connection to TPL's. Maybe look into switching to balanced? I have read where several people have had his problems when using Emotiva amps.

Added
I just read your post above. Reading about many people getting hiss with Emotiva is why I stayed away from them. Besides, pro amps have gain knobs.
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post #63 of 123 Old 05-28-2020, 07:10 PM
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Originally Posted by Wayne A. Pflughaupt View Post
Unfortunately, it seems to be difficult to find a budget processor with a low enough noise floor for a fully-active system.
Not so. You just need to use them correctly. They are designed for very high I/O levels, so that's what you need to do to use them. My DCXs were fine when given a high input level and attenuated outputs.
People just seem to think they can buy any product and shove it in any system and it will work correctly. MD products were designed for a domestic application from the start.
My DCXs with aftermarket I/O boards are silent in low level systems, and unattenuated into CDs are silent.

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post #64 of 123 Old 05-28-2020, 07:17 PM
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If you had to change the boards, doesn't that prove my point?

Can you direct us to a case where someone eliminated background noise with high I/O? Personally I've never seen it, but it is a big world...

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post #65 of 123 Old 05-28-2020, 07:20 PM - Thread Starter
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Not so. You just need to use them correctly. They are designed for very high I/O levels, so that's what you need to do to use them. My DCXs were fine when given a high input level and attenuated outputs.
People just seem to think they can buy any product and shove it in any system and it will work correctly. MD products were designed for a domestic application from the start.
My DCXs with aftermarket I/O boards are silent in low level systems, and unattenuated into CDs are silent.
Hey Brett, you can probably answer this.

You reckon I should get 10db XLR attenuators or 20db?

I have been using Harrison Labs 12db RCA attenuators on the output of the MiniDSP for the past couple years, but I am actually using them backwards now that I looked into it (Male end into MiniDSP output), which lowers the real world attenuation some say, that kinda makes sense since I measured them one day and it was only about 5-6db of attenuation, that's enough to not hear hiss from my seat.

Im a bit worried if I get too high attenuation that I will have to push DSP gain to get reference level output from it.

Ive just had a play with the input gains on this thing, and it looks like the +4dbu option will be good to get the highest SNR possible from the Marantz. I can easily get the input dancing around clipping there with about +6 on the master channel levels in the Marantz vs -8 or so with the -10dbu switch pushed in.

So I am thinking some attenuators on the output should sort me out for clean hiss free sound.

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post #66 of 123 Old 05-28-2020, 07:28 PM
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Originally Posted by Wayne A. Pflughaupt View Post
If you had to change the boards, doesn't that prove my point?
No. I used them in original state for several years then reconfigured the system. About the same time a DIYer I respect a lot offered the boards so I bought them. I like to make stuff so it was as much for that as anything else and it meant I could simplify the system in some other ways. If the boards hadn't fallen into my lap, I would never have bothered.

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Can you direct us to a case where someone eliminated background noise with high I/O? Personally I've never seen it, but it is a big world...
Me. I've posted about it on several forums over the years. The fact that my basically unity gain I/O boards are quiet show that it's not the DSP part of the circuit that's responsible for the noise, but the I/O that's designed for high levels. It's logical really, as in a very noisy environemt such as a PA with lighting and all sorts of other noise makers in near vicinity makes it easier to get a quiet signal to remote amp racks. Why do you think they have attenuators on the from of almost all pro amps?

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post #67 of 123 Old 05-28-2020, 07:38 PM
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Originally Posted by Javs View Post
So I am thinking some attenuators on the output should sort me out for clean hiss free sound.
I think so, but it's hard to guess on the values from a distance. I have a couple of cheap stepped attenuators (ebay, maybe $20) I use to find the amount of attenuation I need, then make them myself. For RCA it's only 2 resistors and 3 for balanced. I find it easiest to build them into the inputs of the amps.

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post #68 of 123 Old 05-29-2020, 04:24 AM
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Originally Posted by Javs View Post
Reading into hiss etc on a number of other sites seem to indicate its usually some kind of mismatch between output impedance and input impedance on the Emotiva amps, not exactly the input gain itself. that would make sense why some people get zero noise vs others.
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I have read where several people have had his problems when using Emotiva amps.
Maybe its worth trying the Rotel you mentioned before, just to guarantee the hiss is not caused by the Emotiva?
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post #69 of 123 Old 05-29-2020, 04:36 AM - Thread Starter
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Maybe its worth trying the Rotel you mentioned before, just to guarantee the hiss is not caused by the Emotiva?
Nah, I'm not going to use the Rotel not enough channels and it's not xlr.

I'm just going to get these attenuators, I know they will work.

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post #70 of 123 Old 05-29-2020, 07:06 AM
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Originally Posted by Javs View Post
So I am thinking some attenuators on the output should sort me out for clean hiss free sound.
I think so, but it's hard to guess on the values from a distance. I have a couple of cheap stepped attenuators (ebay, maybe $20) I use to find the amount of attenuation I need, then make them myself. For RCA it's only 2 resistors and 3 for balanced. I find it easiest to build them into the inputs of the amps.
I don‘t know how much of an impact resistors have on THD, but @notnyt advised against it. I‘m using a voltage divider network for that reason.
An L-pad on the AST would be one way to solve the issue, but an Autoformer would be better (but more expensive and maybe difficult to source, depending on where you are). It‘s true that pro devices operate at a different voltage, which will make the apparent noise floor higher when using it in combination with consumer gear.
Pro gear usually has a 0dbFS (digital domain) reference which translates to somewhere around 19-24dbU, depending on the manufacturer. Now if your AVR outputs 1dbU at max (look up its specs), your noise floor will be 20db higher than what it could possibly be.
I didn‘t catch it, are you using XLR or RCA from the AVR/Preamp?

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post #71 of 123 Old 05-29-2020, 12:47 PM
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I don‘t know how much of an impact resistors have on THD, but @notnyt advised against it. I‘m using a voltage divider network for that reason.

An L-pad...

A voltage divider is made from resistors, and L-pads are variable resistors.

Anyway I've only ever heard of thermionic noise from resistors, not THD.

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post #72 of 123 Old 05-29-2020, 01:02 PM
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A voltage divider is made from resistors, and L-pads are variable resistors.

Anyway I've only ever heard of thermionic noise from resistors, not THD.

Thanks for pointing that out, seems like I have some reading to do. With THD I was refering to distortion in general, it might not have been the correct term to use.
The resistors to use would be of the metal film type, since those have a lower thermal noise than carbon resistors, so potentiometers should only be used for testing. I can't say how big of a difference it actually makes.


Saying that an L-pad is a variable resistor is confusing imo, as one could come to the conclusion that it's similar to a potentiometer.

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post #73 of 123 Old 05-29-2020, 01:43 PM - Thread Starter
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I don‘t know how much of an impact resistors have on THD, but @notnyt advised against it. I‘m using a voltage divider network for that reason.
An L-pad on the AST would be one way to solve the issue, but an Autoformer would be better (but more expensive and maybe difficult to source, depending on where you are). It‘s true that pro devices operate at a different voltage, which will make the apparent noise floor higher when using it in combination with consumer gear.
Pro gear usually has a 0dbFS (digital domain) reference which translates to somewhere around 19-24dbU, depending on the manufacturer. Now if your AVR outputs 1dbU at max (look up its specs), your noise floor will be 20db higher than what it could possibly be.
I didn‘t catch it, are you using XLR or RCA from the AVR/Preamp?
A minidsp is not pro gear and it has exact the same noise floor as this.

Im using RCA on the minidsp and solved it with in line attenuators from parts express (Harrison labs). Been living with that for two years and sound is outstanding, never measured any appreciable I'll effects from them. With the PA2 it will be xlr.

I've ordered 9x 10db xlr attenuators from parts express last night. Will see what happens when they get here. Hopefully it's enough.

https://www.parts-express.com/in-lin...-10db--240-412

Also good news, Sinbosen is going to make a Venu360 clone after I asked them to yesterday, they will be doing it in about two months. This unit I have really is built exceptionally well. I would have confidence in picking up a venu360 from them when they make one.

This PA2 can be used for subs down the track. When these attenuators come though I will use it for my mains for a while. I really should pick up a decent oscilloscope and test the actual noise floor of this and the minidsp.

Emotiva XPA7 Gen2:

Gain: 29 dB.
Input Impedance: 33 kohms (balanced). 23.5 kohms (unbalanced).

Drivrack PA2:

Input Impedance >50 kohm
Output Impedance 120 Ω
Max Output +20dBu
A/D Dynamic Range 112 dB A-weighted, 110 dB unweighted
Type IV Dynamic Range 123 dB with transient material, A-weighted, 22kHz BW; 121 dB with transient material, unweighted, 22kHz BW; 115 dB typical with program material, A-weighted, 22kHz BW
Dynamic Range >110 dB A-weighted, >107dB unweighted
THD+Noise 0.003% typical at +4dBu, 1kHz, 0dB input gain
Interchannel Crosstalk < -110 dB, -120dB typical (input-to-output: < -100 dB)

With specs like that I really shouldnt be able to hear anything.

The MiniDSP has similar specs too.
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post #74 of 123 Old 05-29-2020, 03:49 PM
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Me. I've posted about it on several forums over the years. The fact that my basically unity gain I/O boards are quiet show that it's not the DSP part of the circuit that's responsible for the noise, but the I/O that's designed for high levels.
You’re saying that originally the DCX was noisy, but once you jacked up the input signal the noise went away? Just trying to understand this.

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post #75 of 123 Old 05-29-2020, 04:23 PM
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Saying that an L-pad is a variable resistor is confusing imo, as one could come to the conclusion that it's similar to a potentiometer.

An L-pad *is* a potentiometer, though usually using wire-wound resistors to withstand the higher power dissipation of speaker-level circuits.

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post #76 of 123 Old 05-29-2020, 04:30 PM
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An L-pad *is* a potentiometer
How would that be? I get that a potentiometer could be wired or used as L-pad, but how would an L-pad (consisting of two fixed value resistors for example) be a potentiometer?

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How would that be? I get that a potentiometer could be wired or used as L-pad, but how would an L-pad (consisting of two fixed value resistors for example) be a potentiometer?

You correctly point out that not all L-pads are variable, but neither are they all fixed.

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I've been using the DBX PA2 for several years now. I don't have any problems with the noise floor. I am using it with the Bohlender Graebener RD75 which has a sensitivity of about 88dB so that could be why. I actually have a Venu360 that I picked up on eBay but I haven't had a chance to use it yet. I plan to add a line of 16 BG Neo3 tweeters on the high end so maybe that will change things on the noise issue. The iPad app is pretty cool but a little tricky to get the exact numbers you want using the touch sliders. Used PA2s are surprisingly cheap on eBay. Even the Venu360 can be found for about $400 or sometimes less.
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post #79 of 123 Old 05-29-2020, 11:05 PM
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Do you have any amts? I mean it's not screaming at me, it's just the same as my mini and I can hear it from the chair 3m away.

Perhaps your minidsp is particularly loud sample? This is merely the same.

I don't buy that this clone is louder than an OEM unit.

The pa2 in Australia is $900.....
I have compression drivers that are similarly efficient if not more so.

Too bad you live so far away. For the sake of comparison, I could have send you my OEM DBX unit for a side by side comparison if it was going to a place here in the states. I have a DCX from Behringer and it too is quiet. I switched to the VENU360 for added features. I went the DBX route over the Behringer route for the remote features. I have 3 active systems in my house and none exhibit the noise you are talking about.

It sounds like the padding of the TPL unit would be your best option.
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post #80 of 123 Old 05-31-2020, 04:02 PM
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My DBX PA2 was scheduled for Friday delivery, but seller did not ship, only created label. Tracking then showed Saturday and finally this coming Monday. While out on my run today, I got a Fedex notice of a package delivered. Only Fedex package I was expecting was the DBX. Before putting in my rack, I played with the setting and set up crossovers, driver alignment delay and PEQ, for my 3-way active LCR's. I had an open space right above my Lumagen. Connected everything up, using the same amp gain setting I was using for each driver. Turned everything on and no sound. I had input but no output. So I go looking in the manual to find where the mute buttons are for output, since I did not see them while going through the menu. Turns out, they are right on the front of the unit. Un-muted and I had sound.

So I start playing a movie just to check everything, and I get a pop up message saying my Lumagen was getting hot. Turns out the DBX puts out some heat. I ended up having to remove a shelf and raise up several pieces of equipment in my rack, to get some distance from my Lumagen. By that time, I ran out of time to play with the DBX. I will say, hiss is a non issue in my system. I like the unit, easy to set up and unlike the MiniDSP, does not require me to connect my computer to the system to make changes. Also XLR, not Phoenix connections. Will probably pick up another one.
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post #81 of 123 Old 05-31-2020, 04:16 PM - Thread Starter
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My DBX PA2 was scheduled for Friday delivery, but seller did not ship, only created label. Tracking then showed Saturday and finally this coming Monday. While out on my run today, I got a Fedex notice of a package delivered. Only Fedex package I was expecting was the DBX. Before putting in my rack, I played with the setting and set up crossovers, driver alignment delay and PEQ, for my 3-way active LCR's. I had an open space right above my Lumagen. Connected everything up, using the same amp gain setting I was using for each driver. Turned everything on and no sound. I had input but no output. So I go looking in the manual to find where the mute buttons are for output, since I did not see them while going through the menu. Turns out, they are right on the front of the unit. Un-muted and I had sound.

So I start playing a movie just to check everything, and I get a pop up message saying my Lumagen was getting hot. Turns out the DBX puts out some heat. I ended up having to remove a shelf and raise up several pieces of equipment in my rack, to get some distance from my Lumagen. By that time, I ran out of time to play with the DBX. I will say, hiss is a non issue in my system. I like the unit, easy to set up and unlike the MiniDSP, does not require me to connect my computer to the system to make changes. Also XLR, not Phoenix connections. Will probably pick up another one.
Good feedback, thanks.

Can you do a test for me.

Set your input gains on your power amp to maximum and see if there is a hiss.

My 10db attenuators should be here tomorrow, I am banking on it solving my issue.

In the meantime I sorted out a calibration which will be fine for my L/R channels for the single linked input PEQ bank even though they are not symmetrical in my room.


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post #82 of 123 Old 05-31-2020, 04:20 PM
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I will say, hiss is a non issue in my system.
I saw in your speakers thread that you are powering all the drivers with Crown XLS 1002?

The Crown has a Gain value of +29db, but has Gain knobs.
Given the high gain value and the lack of hiss, maybe Javs hiss is indeed due to the Emotiva?

A user in UK is using a Nakamichi amp, which is similar to an Emotiva XPA-7, and also reported high level of hiss with a BMS 4550 and a miniDSP 2x4HD.
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post #83 of 123 Old 05-31-2020, 04:23 PM - Thread Starter
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Originally Posted by neo_2009 View Post
I saw in your speakers thread that you are powering all the drivers with Crown XLS 1002?

The Crown has a Gain value of +29db, but has Gain knobs.
Given the high gain value and the lack of hiss, maybe Javs hiss is indeed due to the Emotiva?

A user in UK is using a Nakamichi amp, which is similar to an Emotiva XPA-7, and also reported high level of hiss with a BMS 4550 and a miniDSP 2x4HD.
Yeah and with my Mini, the hiss is completely gone with attenuators on my MiniDSP output, so isnt that effectively nerfing the gain on the Emotiva? Same as gain knobs on an amp no?

If that's the case, that's good to know and really no big deal.

Will let everyone know how I go with these XLR attenuators with the PA2.

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post #84 of 123 Old 05-31-2020, 06:11 PM
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Originally Posted by Javs View Post
Good feedback, thanks.

Can you do a test for me.

Set your input gains on your power amp to maximum and see if there is a hiss.

My 10db attenuators should be here tomorrow, I am banking on it solving my issue.

In the meantime I sorted out a calibration which will be fine for my L/R channels for the single linked input PEQ bank even though they are not symmetrical in my room.

I can tomorrow. Wife is in the theater room right now. Nice response on the speaker. You have your mains rolling off to your subs at 30hz? I roll mine off at 40hz.
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post #85 of 123 Old 05-31-2020, 06:19 PM - Thread Starter
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Nice response on the speaker. You have your mains rolling off to your subs at 30hz? I roll mine off at 40hz.
No probs,

Nah I dont bother, I run them full range and high pass them, the high pass is actually at 25hz 48/db, this measurement is a spacial average from 2018 which I still use as the master measurement to calibrate from. The room extension is a bit lower than that.

I dont really miss anything, I know there is some content there, but it just sounds cleaner to me with no LCR info under 25hz going to subs..

For two channel music I have LFE + Main set at 40hz which sounds good to me.

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post #86 of 123 Old 06-01-2020, 07:15 PM
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Originally Posted by peniku8 View Post
I don‘t know how much of an impact resistors have on THD
Zero.


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Originally Posted by peniku8 View Post
I‘m using a voltage divider network for that reason.
Yes, the resistors are used to make a voltage divider.


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Pro gear usually has a 0dbFS (digital domain) reference which translates to somewhere around 19-24dbU, depending on the manufacturer. Now if your AVR outputs 1dbU at max (look up its specs), your noise floor will be 20db higher than what it could possibly be.
I didn‘t catch it, are you using XLR or RCA from the AVR/Preamp?
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post #87 of 123 Old 06-02-2020, 06:39 AM
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Hooked up the PA2 to my home network and tried out the software. I really like this system. Software works great, so easy to use. Since my equipment is located in mechanical room below my theater, not having to connect computer hardwired to equipment, like I did with the MiniDSP, makes this a dream to use. Have ordered second unit for my center channel.
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post #88 of 123 Old 06-02-2020, 12:10 PM
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I have been reading up on the DBX PA2 and liked what I read and I ordered one. Probably will not ship out until tomorrow.
Did you buy a DBX or the copy?
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post #89 of 123 Old 06-02-2020, 02:31 PM
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Did you buy a DBX or the copy?
Both of mine are DBX. Using one and second on the way to me.
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post #90 of 123 Old 06-02-2020, 02:43 PM
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Both of mine are DBX. Using one and second on the way to me.
Any noise?
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