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Old 5th February 2014, 11:28 PM   #1
Xiro is offline Xiro  Sweden
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Default Increasing SPL and low end extention, CHR 70

Hi!

I'm very happy with my CHR 70 gen3 in 12 litre vented cabs. In my smaller room I didn't miss my subwoofer. But now I've moved them to my larger room, and bottom end could have some more energy and extension - also that makes me worry about overloading my sweet CHR 70s.

How much more power and SPL can the CHR 70s handle if I let a subwoofer take over at for example 100 Hz? (Not sure about dB/octave, but I guess maybe around 12 would be appropriate, if subwoofer lowpass is 24 dB/oct.)

Any suggestions on how to make this filtering with minimal loss of quality? I have a subwoofer with built in high pass filter, 100 Hz 6 dB/octave - but I'm not sure about if it will degrade the sound significantly. Maybe there is a better way? I intend to use a computer as source.

Best regards/Johan

Last edited by Xiro; 6th February 2014 at 08:02 AM. Reason: added suwoofer lowpass slope
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Old 6th February 2014, 09:41 AM   #2
JoeyGS is offline JoeyGS  Philippines
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Hi Xiro,

I, too, have the same experience with the CHR 70a gen3.

Why not try integrating a subwoofer without filtering. Try to find out what's the lowest that the chr70a can go then set your subs to come in. You can experiment by ear whether to overlap or follow or have a gap (say 5 db). If your speaker can produce, say, 40hz ...... you can play around for your sub to come in at 50hz or 40hz or 35hz. Remember that you room also plays a part in the overall frequency response/output of the speakers......
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Old 6th February 2014, 11:39 AM   #3
Xiro is offline Xiro  Sweden
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Originally Posted by JoeyGS View Post
Hi Xiro,

I, too, have the same experience with the CHR 70a gen3.

Why not try integrating a subwoofer without filtering. Try to find out what's the lowest that the chr70a can go then set your subs to come in. You can experiment by ear whether to overlap or follow or have a gap (say 5 db). If your speaker can produce, say, 40hz ...... you can play around for your sub to come in at 50hz or 40hz or 35hz. Remember that you room also plays a part in the overall frequency response/output of the speakers......
Thanks for your ideas Joey. That would certainly be an option if I was just after bass extension and not more spl.

In my smaller room, with modest SPL, I can clearly detect sinus from slightly below 30 Hz, and it fells like full level at a bit above 30 Hz. I did not expect this from these small CHR 70s, I'm amazed!

In my larger room I feel the bottom end is a tiny bit too weak, and as you say I can try to compensate by a subwoofer without filtering. But also I need more power fore same SPL. That is why I'm considering highpassing them - to protect them from excessive excursion and heat. But I haven't figured out the best way to do so. Also I'm curious to know how much more power and spl highpassed CHR 70s would handle.

Edit: And to be clear, as you already suggested, the differences between my two rooms are just that, room related. Not related to CHR 70. I've had the same experience with other speakers.

Last edited by Xiro; 6th February 2014 at 11:44 AM.
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Old 6th February 2014, 05:08 PM   #4
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Xiro,

I have never highpassed any of the MarkAudio drivers but I have spent a lot of time reading these forums. Based on that reading and also on some logic, I would say that you will certainly be able to get more SPL out of the CHR-70s by highpassing them. The biggest threat of damage, as you know, is from excessive excursion, and you will reach that excursion limit at lower SPLs if you are pushing the full signal through them. Cut them off at 100Hz or so and they will go louder (with better coherence).

Regarding crossovers, again I have very little direct experience. Again, based on much reading here, I would say that an active crossover seems to be the easiest and (often) the most cost effective way to get it done. I have heard a lot about miniDSP but it seems there are newer units that keep everything in the digital realm until the final amplification stage (instead of DAC-ADC-DAC as in miniDSP). The beauty of an active crossover is that it can be changed in infinite ways and used for other projects down the road. Invest once and you may never need to buy any passive crossover components again.

My approach to the issue has been quite different. I have tried subs, but I have not yet heard a sub that sounded good to me. Not even in the "hi-fi" shop. Apparently there are good, "musical" subs out there and there are good DIY options. However, whenever I look into building one I discover that the cost of building a "really good" sub (usually "subs" not "sub") is astronomical. Therefore, my answer to the bass question is; use twice as many full range drivers and put them in a cabinet design that gets the most out of them. Time will tell whether this will be a satisfying solution over the long term.

Last edited by cogitech; 6th February 2014 at 05:22 PM.
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Old 6th February 2014, 06:57 PM   #5
chrisb is offline chrisb  Canada
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Johan - when you say "computer as source" what degree of control / EQ / XO filtering would your player software offer, and would you be using analog or digital output?

There's mixed blessings to be found in current DSP devices/sofware - many members here are quite happy with the functionality of mini- or nano-DSP etc.

My own experience in this realm has been mostly been with HT surround receivers, which offer a lot of flexibility in DSP with a mostly user friendly interface. I 'm trying to talk myself into trying something like the nanoDSP, but have spent more than 10yrs attempting to simplify and streamline the number of "black boxes" - old habits die hard

I share some of cogitech's experience / exasperation in finding decent "subs" to integrate seamlessly with small FR drivers, but to saddle up one of my favorite hobby horses, I think a big problem is the design/ marketing of commercial products to cater to the "sub" mentality -i.e. if you can't hear / feel it as a distinct source, and if it can't rattle the neighbour's china cabinet, or interrupt peristalsis, it's not a real sub- (OK, maybe that's hyperbole)

I've been to only a couple of recent cinema releases, and the last thing I want from any home system is to recreate that sensory overload.


I've found that multiples of smaller mid-bass drivers without nasty upper register response, in enclosures aligned for shallow low-end rolloff, and taking advantage of room gain can work very well, and blend quite nicely. And, FWIW, I've moved away from using internal "plate" amps for woofers.

To the question, I'd suggest dual woofers (6-8"), crossed over as high as 120 or so, and definitely HP the CHRs - actively if possible, by either passive line level or something like nanoDSP. I'd also be inclined to bypass the internal line level XO of sub amp for greater flexibility of filter points and slopes.
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Last edited by chrisb; 6th February 2014 at 06:59 PM.
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Old 6th February 2014, 06:57 PM   #6
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I am just starting to play with the nanoDIGI. It is a 2 x 8 SPDIF in SPDIF out solution. You will need 2-4 DAC's and 2-4 stereo amps. You get the choice of two plug-ins, 24/48 or 24/96. The 24/48 has an input PEQ plus an output PEQ for each channel. The 24/96 does not have the input PEQ. I am not sure the all digital sounds better than the miniDSP, but I feel better about it.

I am using a real subwoofer, not a low mid woof. As such, the best thing I did was upgrade the sub amp. An A10P high passed at 200Hz is crazy loud with 30w/ch. with 75w/ch on the subs, they could not keep up. Now I have 575w/ch on them and all is well, although I had to ack them down a few dB in the nanoDIGI

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Old 6th February 2014, 07:02 PM   #7
chrisb is offline chrisb  Canada
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remind me again Bob, what "real" subs are you using
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Old 6th February 2014, 08:12 PM   #8
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All of this discussion has me just about to pull the trigger on a miniDSP 2x4. Even if I end up really loving my quad of Alpair 10s, it would be really, really fun to play with a miniDSP and see what happens if I throw everything below 60Hz at my alnico 12" paper cones (in H-frames!), powered by a decent class D amp. The miniDSP's 31-band EQ might come in handy, too.

Longevity of the fullrangers would likely benefit greatly, too... hmmm

Last edited by cogitech; 6th February 2014 at 08:32 PM.
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Old 6th February 2014, 09:40 PM   #9
Xiro is offline Xiro  Sweden
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Quote:
Originally Posted by cogitech View Post
Xiro,

I have never highpassed any of the MarkAudio drivers but I have spent a lot of time reading these forums. Based on that reading and also on some logic, I would say that you will certainly be able to get more SPL out of the CHR-70s by highpassing them. The biggest threat of damage, as you know, is from excessive excursion, and you will reach that excursion limit at lower SPLs if you are pushing the full signal through them. Cut them off at 100Hz or so and they will go louder (with better coherence).

Regarding crossovers, again I have very little direct experience. Again, based on much reading here, I would say that an active crossover seems to be the easiest and (often) the most cost effective way to get it done. I have heard a lot about miniDSP but it seems there are newer units that keep everything in the digital realm until the final amplification stage (instead of DAC-ADC-DAC as in miniDSP). The beauty of an active crossover is that it can be changed in infinite ways and used for other projects down the road. Invest once and you may never need to buy any passive crossover components again.

My approach to the issue has been quite different. I have tried subs, but I have not yet heard a sub that sounded good to me. Not even in the "hi-fi" shop. Apparently there are good, "musical" subs out there and there are good DIY options. However, whenever I look into building one I discover that the cost of building a "really good" sub (usually "subs" not "sub") is astronomical. Therefore, my answer to the bass question is; use twice as many full range drivers and put them in a cabinet design that gets the most out of them. Time will tell whether this will be a satisfying solution over the long term.
Thanks Cogi,

I thought a miniDSP with digital input was all digital until the final conversion to analog - if it is not I think I'd better look out for something that is. Further on the miniDSP I've read that some have a problem with the limited analogue level in some setups. And I've read some complaints about the sound quality.

I have also had a hard time with my subwoofer, an Audio Pro Evo Sub 8 DC, 175W active ported 8", with stepless 24dB/oct lowpass, and fixed 100Hz 6dB/oct highpass. Finally, efter a few years, I'm quite happy with it. Now it is found in a corner, with a pair och old socks plugging the port, and reversed phase. I guess it would improve further with a good active crossover solution, and some PEQ.

Your thought on twin CHR 70 is interesting - seems I'd reach a bit more SPL and power handling than a pair Alpair 10M for half the money. And the CHR 70 extension downwards is similar, or maybe even better? And the volume needed for good bass extension, CHR 70 vs A10M is roughly similar?

It is a nice simple solution. If I'd find the excursion margin sufficient with twin CHR 70, I could just make a slight bass lift by EQ in my player (if I find the courage :-) ) to eliminate the need of a subwoofer for extension. And if I ever want to play cray loud I'd just switch off the bass lift, or even EQ out the deepest bass.

I use EQ in Foobar2000 when I'm working, and I haven't noticed any degradation of the sound yet, even when listening to 96/24 material. My only concern with twin CHR 70 is going away from a near perfect point source - but maybe I shouldn't worry about that?

Best regards /Johan

Last edited by Xiro; 6th February 2014 at 09:42 PM. Reason: paragraph breaks
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Old 6th February 2014, 10:06 PM   #10
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Johan,

MiniDSP is analog in and analog out, with a ADC-DigitalProcessing-DAC chain.

miniDIGI and nanoDIGI are SPDIF/Toslink in and SPDIF out.

I agree it would be best to avoid the ADC-DigitalProcessing-DAC chain of the miniDSP, but the "all digital" versions require one to purchase at least one more external DAC. I have also just read a very unflattering review of the miniDSP. I take it all with a grain of salt, because Bob Brines lived with his miniDSP for quite some time and I do trust his opinion.

Your reasoning on the dual-CHR-70 option is good, I think. You'll still need to treat the drivers with respect, of course, but the output certainly will have more "impact".

I understand your concern about point source. There is also the larger issue of having to build a pair of new boxes for the 4 drivers. Here are two options that you might consider:

CHR 70A Gen3 Dual Driver for Pensil

microTower bipolar ML-TL for CHR-70 or EL70

There are also Wessex and Mercia:

http://frugal-phile.com/boxlib/woden...v92-151209.pdf

http://frugal-phile.com/boxlib/woden...v92-151209.pdf

Last edited by cogitech; 6th February 2014 at 10:11 PM.
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