Art cleanbox testing by Ilkkaa

[kingpin]

I knew removing my cleanbox was like lifting a veil off my speakers.
I removed it a couple weeks ago after a long listening session. Something wasn't sounding right. So it was one of the first things I got rid of.

Quote from Ilkka.

"Since the ART Cleanbox is often recommended to those having low signal level problems with their pro amps, I thought to try it out. For my disappointment, it turned out to be less than adequate for my needs.

Here's its frequency response (measuring system is flat).

As you can see, its FR starts to roll off already at ~200 Hz. Here are some numbers:

Frequency / "Down" at that frequency
100 Hz / -0.4 dB
50 Hz / -1.5 dB
20 Hz / -5.4 dB
10 Hz / -10.3 dB
5 Hz / -15.9 dB
2 Hz / -22.6 dB

So unless your system definitely needs some extra protection down low, or you have too much "room gain", I wouldn't recommend using it. It's like adding an extra ~1st order high pass filter at ~30 Hz.

I also found out that it adds some noise (low S/N ratio) into the system.

My ART Cleanbox is for sale. Anyone?"

Image not available

From htshack and Ilkka

[jdb]

I took my cleanbox out of the signal chain recently also. I agree about the lifting of the veil. I picked up an SVS01 to use in its place. It has adjustable gain, 0-180 phase control and a 15, 20, 25 Hz adjustable subsonic filter. It was made by Marchand for SVS, but is no longer in production.

[chasw98]

Which is why Thomas and I have been building and testing a 'Black Box' that we have named the H.A.L.F. box (Help At Low Frequencies). It has provisions for a high pass filter with points at anywhere from 8 Hz to 24 Hz in 2 Hz increments, 0-360 phase adjustment, and balanced or unblanced outputs. Of course it is DIY! We should shortly be providing circuit boards and a parts list to build them along with detailed build instructions. Hoping to keep the cost under $50.






Chuck

[Gir]

Which is why Thomas and I have been building and testing a 'Black Box' that we have named the H.A.L.F. box (Help At Low Frequencies). It has provisions for a high pass filter with points at anywhere from 8 Hz to 24 Hz in 2 Hz increments, 0-360 phase adjustment, and balanced or unblanced outputs. Of course it is DIY! We should shortly be providing circuit boards and a parts list to build them along with detailed build instructions. Hoping to keep the cost under $50.

Very exciting Chuck! I'll definitely have to build one.

[augerpro]

Which is why Thomas and I have been building and testing a 'Black Box' that we have named the H.A.L.F. box (Help At Low Frequencies). It has provisions for a high pass filter with points at anywhere from 8 Hz to 24 Hz in 2 Hz increments, 0-360 phase adjustment, and balanced or unblanced outputs. Of course it is DIY! We should shortly be providing circuit boards and a parts list to build them along with detailed build instructions. Hoping to keep the cost under $50.






Chuck

Are the LP and HP bypassable? Adjustable gain included? LT or shelving circuit? And most importantly for me, could I use this in a biamped 3 way for the woofer section just to raise the prior to the amp for BSC? If you could implement these I'd be SO GRATEFUL you have no idea! I'm trying to learn enough basis electronics to design one myself, but with the time involved i don't think I could before it was needed for a speaker.

[chasw98]

Are the LP and HP bypassable?

There is no LP. HP is adjustable in 2 Hz increments through plug in modules. Yes, it is bypassable.

Adjustable gain included?

No.

LT or shelving circuit?

No.

And most importantly for me, could I use this in a biamped 3 way for the woofer section just to raise the prior to the amp for BSC?

This is a mono unit so you would need 2 for stereo. I am not sure what 'raise the prior' is referring to. Explain, please.

If you could implement these I'd be SO GRATEFUL you have no idea! I'm trying to learn enough basis electronics to design one myself, but with the time involved i don't think I could before it was needed for a speaker.

This was designed to have very, very good fidelity, yet be reasonable in cost and perform some basic functions for ordinary, run of the mill IB's or subs. This was meant to offer functions that are found on plate amps and not on pro power amps or in HT pre/pro's or receivers. When you start talking about LT or shelving circuits, you are much better off getting a kit from Phil Marchand for that use.

Chuck

[augerpro]

I reread your post and seen there was no LP. Sorry.

I meant to say "raise the level prior to the amp"

I'll have to check out the Phil Marchand kit. Thanks for the tip Chuck.

[JonW]

For what it’s worth…
I’ve got a Clean Box in my system now. I didn’t need it at first. But when I added a BFD, I felt like the sub needed a little boost. The Clean Box gave the needed boost plenty. Unfortunately, the Clean Box also brought along an annoying 60 Hz hum to the party.

I’ve got a cheater plug on the BFD and that maybe takes out 80% of the hum but it’s still there and a little annoying. I tried figuring out the source of the hum, trying different combinations of things in the chain, cheater plugs, etc. Near as I can tell, the hum may have always been there but I wasn’t able to hear it. And now it’s amplified by the Clean Box. (I’m using a Crown K1 amp and a DIY sonosub.)

I’d be more aggressive about fixing the problem but my current system is kind of temporary. When my next DIY speaker project (Spassvogel MT’s) is done, I’ll probably be changing things around a bit. Man, I can’t wait until work calms down and I can get back to making speakers.

[soho54]

For those who already have the Clean Box, the HP fix is pretty easy if you aren't afraid of a little soldering.

Run down to Rat Shack, and pick up two .47uF or four .22uF Poly/Film Caps.

Open up the Box by removing the many screws. Leave the one in the top corner on the back side alone. It's the ground.

Now just add one .47uF or two .22uF caps to the green .047uF caps at c7 & c8.

Put it back together, and you are done. This will give you a ~3Hz 1st Order HP, instead of the one that slipped past everyone.

I got 4dB back at 20Hz, and 11dB at 10Hz. Uncorrected. I won't notice it though. I had already EQ'ed it flat, I'll just pull the boost out now. :B If you don't have EQ, this is an easy mod if you are going to continue using it.