AVS Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
99 Posts
Discussion Starter #1
Hi all,

Quick question, seeing that the Crown 1502 amp has an RCA input, does it mean I don't need to use a CleanBoxPro as with maybe the iNuke?


Thanks!
 

·
Registered
Joined
·
1,478 Posts
You need to look at how much voltage the amp will require, the RCA being the main input doesn't mean much other than it probably WON"T need the cleanbox. You can try connecting the Amp first and see how much output you get from just the RCA connection to see if you need to up the voltage a bit.
 

·
Registered
Joined
·
63 Posts
Hi all,

Quick question, seeing that the Crown 1502 amp has an RCA input, does it mean I don't need to use a CleanBoxPro as with maybe the iNuke?


Thanks!
I previously used two Crown XLS 1502s with a cleanbox pro.

That said, since you can set the Crowns input voltage from 1.4v down to 0.775 (something like that) you SHOULDN'T need a cleanbox pro... but for some reason it seemed to have made a positive difference for me (I also liked running it at 1.4v)

I did some experimentation prior to buying the cleanbox pro and I felt there was a positive benefit (Crowns for sub duty, both bridged at 4ohms) when I introduced it. Prior to using the cleanbox, I did experiment with changing input voltage from 1.4v to 0.775 but there could have been other issues with my gain structure. I feel like it shouldn't have been necessary, but it did really help me. No added noise or anything, just had to make sure you didn't turn the cleanbox pro on or off with your Crown amp on; you get a very loud thump otherwise. I used the cleanbox at about 35-40% gain.

I no longer use my Crown XLS 1502s or cleanbox pro, as I upgraded to Crown XLS 2002s which seem to power my DS4 18's (sealed boxes) much better.

For reference, receiver is a Yamaha RX-A3060

Hope that helps,
 

·
Registered
Joined
·
130 Posts
Maybe also consider the Samson S-Convert as I believe the Cleanbox has a roll off from 20hz.
I've used one in all my pro amp setups (EP4000, iNukes and Lab Clones) and I believe my mate needed one in his Crown which was the first gen of their lightweight amps.
I've also had noise/hum over the years and the Jensen Sub 1RR (ISO-MAX) has been the only filter that's ever worked but they aren't cheap...
 

·
Registered
Joined
·
63 Posts
Maybe also consider the Samson S-Convert as I believe the Cleanbox has a roll off from 20hz.
I've used one in all my pro amp setups (EP4000, iNukes and Lab Clones) and I believe my mate needed one in his Crown which was the first gen of their lightweight amps.
I've also had noise/hum over the years and the Jensen Sub 1RR (ISO-MAX) has been the only filter that's ever worked but they aren't cheap...
Original cleanbox may have been worse, but you are right, it does start rolling off.

Per this discussion here https://www.avsforum.com/forum/155-diy-speakers-subs/1628737-art-cleanbox-pro-mod.html, looks like about -3db @ 8hz, which is not bad at all IMO.

They also allude that the Samson starts rolling off at 10hz and that the "aphex 124a goes to 5hz before any rolloff" - I have never looked into an Aphex though.

Food for thought
 

·
Registered
Joined
·
1,676 Posts
Original cleanbox may have been worse, but you are right, it does start rolling off.

Per this discussion here https://www.avsforum.com/forum/155-diy-speakers-subs/1628737-art-cleanbox-pro-mod.html, looks like about -3db @ 8hz, which is not bad at all IMO.

They also allude that the Samson starts rolling off at 10hz and that the "aphex 124a goes to 5hz before any rolloff" - I have never looked into an Aphex though.

Food for thought
Also consider the Henry Matchbox HD if you do need a bump box, but I would say you should be ok using the rca level inputs.

Sent from my SM-N920V using Tapatalk
 

·
Registered
Joined
·
3,500 Posts
Can a miniDSP 2x4HD also be used to boost the signal voltage?
Not really. Indeed, rather than boosting the signal, people have had problems with that thing being a choke-point in the signal chain, since it can be set to accept 4V, yet can only output 2V. Gotta wonder who thought that was a good idea...

Regards,
Wayne A. Pflughaupt
 

·
Registered
Joined
·
435 Posts
Not really. Indeed, rather than boosting the signal, people have had problems with that thing being a choke-point in the signal chain, since it can be set to accept 4V, yet can only output 2V. Gotta wonder who thought that was a good idea...

Regards,
Wayne A. Pflughaupt
Yes, but I'd say the largest part of users hooking up pro amps are using an AVR rather than a pre/pro and not eclipsing the 2v choke point. Most AVR users would love to be able to get to 2V on their sub out signal. With that said, AVR users should benefit from a signal booster like the 2X4HD. Just be wary of the regular 2X4, output voltage is roughly half of the HD.

And my .02c, I have a Denon AVR-X4200W with a XLS1502 and can drive the amp into the red at +2db on the AVR sub out, so I don't need a booster. I also have the Crown set to .775v sensitivity. I've heard some AVRs (I think Yamaha) have poor sub out voltage, so YMMV.
 

·
Registered
Joined
·
6,307 Posts
Not really. Indeed, rather than boosting the signal, people have had problems with that thing being a choke-point in the signal chain, since it can be set to accept 4V, yet can only output 2V. Gotta wonder who thought that was a good idea...

Regards,
Wayne A. Pflughaupt
For the HD that is correct, however if one were to choose the balanced model, I believe it can output 4VRMS, unless I'm mistaken. I use the 2x4 balanced on my older Crown XLS2000 (because they dont have a input sensitivity and I wanted DSP abilities). Thats not to say the 2x4 balanced doesn't potentially have problems DSP wise compared to the HD, but thats a different topic.
 

·
Registered
Joined
·
238 Posts
And my .02c, I have a Denon AVR-X4200W with a XLS1502 and can drive the amp into the red at +2db on the AVR sub out, so I don't need a booster. I also have the Crown set to .775v sensitivity. I've heard some AVRs (I think Yamaha) have poor sub out voltage, so YMMV.
@notfastenough May I ask what your sub trims are in speaker settings? Mine are 0dB on the X4300h and I cant drive the XLS 2002 at all without the Cleanbox. Thx
 

·
Registered
Joined
·
435 Posts
@notfastenough May I ask what your sub trims are in speaker settings? Mine are 0dB on the X4300h and I cant drive the XLS 2002 at all without the Cleanbox. Thx
I did not remember my sub trim 100% accurately, but close. I'm able to tickle the red lights with bass heavy scenes at +3.5db on the sub out. My main volume is usually around -10 to -5 for that. If I'm not wanting complaints from the neighbors, I set the Crown knobs to just below half. If it's full steam ahead, they are around 2 or 3 o'clock:devil::devil::devil: Generally, your sub out voltage is a function of three things: crossovers, main volume, sub out levels(trim). If you never turn your mv past -25 and leave your sub trim at 0db, you aren't pushing any signal voltage from your sub out.

The only time I crank the knobs higher than that is with music that I want to demo with. I've always had to turn up the subs with bass/electronic music to suit my tastes. I've always assumed it's just my tastes and has nothing to do with the equipment or source materials. Movies don't really feel like they need the extra power for me.

One thing to consider with my setup and attenuation, my subs are very sensitive horns that are very high sensitivity. Sealed setups require far more power and if you don't have the gain structure set correctly, the power will not be there. I'd say, don't be afraid of adding some trim to your AVR's sub out. There is another Crown thread on the first page here that has a link to how to set up gain structure, definitely give that a look. Best of luck with your setup and let us know how it goes!
 

·
Registered
Joined
·
238 Posts
I'm able to tickle the red lights with bass heavy scenes at +3.5db on the sub out. My main volume is usually around -10 to -5 for that.
Ok thanks for that. I listen between -20 and -30. My room is 12 x 14 x 7 with MLP 9 feet from the front soundstage. I think if I listened at -5 I would go deaf :)
I think difference in MV and SUB trim may be the big difference. I can certainly bump the trim some but recall reading (but not the explanation) that sub trim should be 0 or lower (i.e. negative values).
 

·
Registered
Joined
·
435 Posts
Hmm, not sure about NEEDING to be at 0. Full max or full min usually is a good indicator the gain structure has room for improvement. However, if you never eclipse -20 for MV, I'd say boost up to +8db to suit your palate. I think that you'll find what you need before that regarding the amp signal lights. Suiting your needs for output depends on efficiency of your system and room.
 
1 - 15 of 15 Posts
Top