I may be wrong, but I don't think it will do balanced to balanced. I think it'll do balanced to unbalanced or unbalanced to balanced.

 

What does it actually do to the avr going to the amplifier? Is it a boost to signal or a boost to the voltage from the avr?

 

Is it a boost to signal or a boost to the voltage from the avr?

Yes

 

It will boost the voltage output of the preamp to be compatible with pro level components.

It has controls so you can vary the output to your power amp.

If I recall, it also will step down XLR to RCA voltage levels.

I use one between my Yamaha AVR and Crown pro amp. The additional gain came in handy when I added a non HD MiniDSP to my system which has limited output.

Note that newer Crown ( and other pro amps) have both XLR and RCA inputs with the appropriate gain stage for the RCA's.

 

I use a Cleanbox Pro between my Anthem MRX 1140 and my Crown XLi 2500 that powers my front 2 subs. There was a hum in the Crown, and their tech support told me about the CBP, which has eliminated the hum, and the CBP has up to 21 Db of gain if needed. Highly commend its use.

 

Hi,

Hrm, so what would be the procedure to adjust the output voltage on the Cleanbox? I see the attenuation knobs, but they a smooth attenuator and how much range does that really give for output or does it have click-stops so you can match the two attenuators? Do you have to measure their output manually yourself to know what they're doing? Can you use both the unbalanced and balanced input/output together (I only ask for cable simplicity, such as using RCA input and XLR output, but on this box they are unbalanced vs balanced)?

I currently do no have an issue but I'm just curious. I currently run my AVR to my miniDSP HD and then it outputs to some NX3000 amplifiers. I leave the NX3000 volume attenuation knobs at maximum and I adjust their from within the MiniDSP HD. I generally run use up to -10db or -6db on two of them for output to keep them from clipping during very intense movies with heavy signal (I find so many films will ask for a +15~20db signal in the LFE) and I listen around 85~95db sometimes on a movie, so the bass track will spike into the 110+db range. Currently it only starts to clip when it's asked to go over 115db, which I cannot even measure (my microphone clips at 115db, Umik-1). But I often wonder what my signal pathway is and what would be ideal for the NX3000 to get the most out of them.

Very best,

 

Hrm, so what would be the procedure to adjust the output voltage on the Cleanbox? I see the attenuation knobs, but they a smooth attenuator and how much range does that really give for output or does it have click-stops so you can match the two attenuators?

That really depends on what you want out of them.

They are balancing/unbalancing interface adapters that allow voltage gain adjustments, with pretty significant positive range.

Positive clicks are reassurring, but they don't ensure that the same clicked in position delivers the same gain. See the ASR review on the Behringer NX3000D amplifier.

If you really want to set any of this optimally, from an ideal interface matching standpoint, you run a known level test signal through the system, bust out a meter, and measure it. But I don't think that's what most people on this forum are actually after. Rather, they want to get enough gain, without clipping, without having to measure levels systematically, which is what makes something like this so useful.

In that regard, the safest starting approach is to turn ALL the knobs full up on the power amplifier and the Cleanbox or whatever gain/balancing device is, run the AVR at a low trim output (though not the lowest after whatever calibration you use, so you know that it didn't run out of bottom), and your signal should have plenty of headroom to prevent clipping the MiniDSP input (which seems to be where most of these problems arise, not because the AVR lacks voltage output capability) and offset the 'only negative gain/filter' settings that many users of MiniDSP devices implement with a substantial positive gain following that device. The cost of doing this is an elevated noise floor, but unless you have ground-related problems, (60 Hz hum or related buzz harmonic components) I would guess that most users aren't going to hear much of any hiss through their subwoofers due to bandwidth limitations, and aren't prioritizing system silence anyway.

 

I use an ART Cleanbox in one of my cars. The head unit I put in there did not have enough output to fully drive the power amp I had also recently installed.
I have the XLR input and XLR output tied together. In this fashion it takes a low level RCA input and amplifies it enough on the RCA output to correctly drive the amp.
I am running it off the +12v in the car, no problem.

 

The only issue with the Cleanbox that I didn't see mentioned here is it rolls off signal below 20Hz. I don't know how significantly but I do remember reading about it.

I feel like for 90% of people it's not actually needed as long as you set your gain structure up properly. If you have a MiniDSP, it outputs 2V which is plenty for any amp I've used. Just have to set your input/output sliders accordingly.

 

The only issue with the Cleanbox that I didn't see mentioned here is it rolls off signal below 20Hz.

Ew, I don't want that then. Most of what I would use it on is a system all about that 20hz range.

Very best,

 

There are other brands that don't roll off the signal below 20 hz.

 

Sweet, any links to anything remotely affordable?

Very best,

 

Great tutorial. As was previously stated, different content can boost certain frequencies causing clipping. If you run the avr signal well below any amp clipping then the bass is less pronounced.

 

Maybe one day I'll do some testing and see if that Cleanbox roll-off or not.
I do have the equipment to do so. Would be interesting to see if it does introduce a roll-off below 20Hz. That's not what most people on here would want to have happen. I only listen to music so I would probably never really know.

 

If you're seeing the clip lights flash, you're giving enough voltage to clip the amp. When you reduced the subs to -6 and -10, that lowered the voltage 4x and 10x respectively. Adding a cleanbox back in won't do anything. You'd just be adding back in that voltage you removed and you'd be back to clipping again.

 

Adding a cleanbox back in won't do anything. You'd just be adding back in that voltage you removed and you'd be back to clipping again.

Take it away, so you can pay more to put it back in one more box.

 

My understanding is movies and even music videos I play through tidal have a +10db boost compared to music on the LFE channel by design and it certainly seems that way with my setup , Denon X3700 - minidsp 2 x 4HD - NX6000 , your leds on the NX3000 tell you everything you need to know about how hard it is being driven , if you are hitting the limiter led then you are driving the amp to its maximum output and a cleanbox won't help , I don't need one as I can drive my NX6000 into the limiter leds

 

I'm not saying @Teeeejay is wrong...

But it IS okay to be satisfied with output levels that are below the maximum of what your drivers can do. At least, I am

 

I'm not saying @Teeeejay is wrong...

But it IS okay to be satisfied with output levels that are below the maximum of what your drivers can do. At least, I am

Isn't that really the goal? SPL satisfaction with the drivers barely breaking a sweat. That's what I'm striving for at least.

 

Sorry to revive a dead thread, but I got a CleanBox to act between my Yamaha AVR and a crown Amp. I set it up and it definitely boosts the signal. Is there a "best recommended" method for balancing the volume knob on the AVR, the gain knobs on the amp, and the volume on the CleanBox?

 

You want to do a spread sheet? Are you willing to run a digital volt meter and a signal generator (REW has one built in) at the same time? Can you get your maximum output/input levels for each piece of gear?

 

Man is after my own heart.
I too have a Yamaha AVR with an ART Cleanbox and a MiniDSP feeding a Crown amp and a Berry amp...........
Just spit-balling here, run the attenuators on your amp at 3/4 (almost all the way down, almost the least amount of attenuation, or it you want to look at them as volume controls, then almost all the way up.)
Then adjust the Cleanbox to get the amp output to what you want. I bet mine is about 1/2 or just past there.

Yes, a voltmeter is the correct way to do this, but my method will get you going.

 

I would start there.

He's got the same stuff, and happy with it, real world experience matters.

 

And by the way, that Cleanbox will attenuate your bass response pretty bad below 20Hz or so. Just to let you know. I ran tests on mine awhile ago and was very surprised, but since I am only listening to music it has little effect on my system.

 

Appreciated!
What voltage do you run the crown at?

 

What's a MiniDSP?

 

DSP processor.

I made you a 'gain chain' spreadsheet anyway, based on the specifications of your equipment. I put a DSP with gain of '0' in it for future use. It's pretty close to a theoretical 'ideal' based on manufacturer specifications and assumptions on input sensitivity, but since none of that equipment actually displays gain (and you might not be able to trust it if it did) you might still want to verify gain with a meter. If for no other reason than our own entertainment, this would be a rough approximation of 'ideal' with that equipment set, with the target of being able to adjust the Yamaha output with either volume or trim to allow you to reach full rated power, and a little more from the subwoofer amplifier. it would be at least a 'best practice' starting point, with adjustments made perhaps for use context, and it might illustrate content discussed previously in the thread.

Your Yamaha AVR preouts are rated at 1 volt. That doesn't mean they can't do more. They likely can, but that's what you know it can do.

DSP, you have none, so gain is set at zero.

Clean box pro, has a maximum output voltage listed of 21 dBu, which correlates to 8.69 volts, about. So if you exceed that, you can clip the output. With one volt input, and 18 dB of gain, that will bump the output to almost 8 volts, which is a nice round number close to, but not flirting with the edge of maximum rated output. Maybe it can do more, who knows. It has 21 dB of gain, so you definitely can clip it with your Yamaha before the Yamaha clips, even if it was limited truly to 1 volt, which is actually as designed, but just be aware.

The Amps list input sensitivity as 0.775 and 1.4 for high and default gain settings, but they don't specify the ohm load for the power rating, so i'm just using 8 ohms, as that rating would e the highest voltage. That correlates to 34.5 dB of gain in the amp at high gain, and 29.4 dB of gain in the low setting, which is the gain with the knobs turned all the way up. if you adjust the 'gain' knobs so that you cut down that to 16 dB of gain, your 1 volt Yamaha output, through the clean box pro serving up 18 dB of gain, will deliver voltage equivalent to power in the upper right hand side in the blue fields, beyond rated power, the degree of which will depend on the load, and is expressed in dB of possibly used 'headroom' if the amp has it, on the furthest right column.

The second set of numbers are at 1/8 voltage, or 18 dB down from theoretical 'maximum', if you were inclined to actually check the gain relationships (because everything will scale) without actually running a signal at full power, because you might break something

Also, as an alternative, if you don't actually need the gain or balancing circuitry of the clean box pro (for reasons like the Yamaha subwoofer output trim and amplifier with the gain set at maximum just won't let you set the subwoofer output loud enough to get the sound you want, or the balancing and impedance matching benefits of the CBP give you better noise performance), if you simply run the gain of the amp on maximum and connect the yamaha directly...

 

😂😂😂