Considering Purifi vs Hypex MP but don't want to overpower LS50's

[SHB]

???
I hope the setup you suggest is having the subs as a base to mains, or tightly close, or else a 170Hz x-over for non- collocated subs with mains is astronomically high.
The 1/4 wavelength rule for x-overs alone is enough.

I’m using the active crossovers in my pre/pro.

Also, the left and right speakers each sit on top of two, stacked Rythmik L12 subs. They run in stereo.

People forget or don’t realize that the bottom octave covered by any speaker will usually be the area most dominated by distortion. LS50’s -3dB point is around 80Hz so 170Hz (based on measurements I’ve seen) is ideal.

 

[john61ct]

This is EXACTLY in line with my case, but my LS50s are the OG model before the Meta line (similar power handling I believe). My goal is to get "maximum safe" SPL out of them.

These speakers require an amp with both high Damping factor AND high Current to overcome voltage drop, due to the fact that their "nominal" impedance in reality can drop down to 4Ω or even a bit lower.

All that means well over 100W continuous and HIGHER for peaks is better than lower, as you state headroom is A Good Thing.

Many say Class D is better than "chip amps" but measurement says, not always especially when price is important.

My benchmark for "ideal" current / power delivery for LS50 is GFA-555, Parasound HCA line, "1200 II", 2205a for multi-channel, HCA-800ii bridged.

I recently came across Proton D1200 and NAD 2200 "Power Tracker" tech too but unobtainium.

The Purify, nCore, Hypex and Benchmark lines obviously are great, IMO Schiit Vidar look good and I agree Topping B200 would be great - all just out of my budget. 8-(

Also, critically, I'm looking for **DC-powered amps** that approach those levels but that don't cost the earth.

...

The other factor mentioned above is also critical, and that is Bass Management. High Pass filtering the LS50 signal will allow higher "safe SPL" with less demand for the peak power requirements.

As mentioned, having all that headroom cannot hurt, so long as you know you will keep output turned down to safe levels. Start playing with DSPs though, beware!

Also the LS50 family are weak SPL at the low end anyway. I am looking at adding co-located stereo "basstand" MBM modules to "reinforce" the 40-200Hz range (or even higher?), and maybe not even need any BRuTeS (Bone Rattling fUll-size TruE Sub) for the bottom end. Maybe a smallish singleton for room modes.

Nearly everyone here says to go multi-channel DSP to handle the crossovers, but pricey, and since that is often included in car amps for hardly any extra cost and I need DC powered amps anyway...

I also have an old school Outlaw ICBM-1 to work with.

Finally, my household includes partying teens, with stupid friends over often when I'm not home, so I am hoping to find **technical** solutions to protect my LS50s

Thinking maybe an SPL-monitor triggering a strobe light at level A, power shutdown at level B (not joking but lack of skillz, need good guidance).

I also found a Alesis 3632 cheap on eBay to try as a peak limiter, but not sure how well that will work, might affect SQ?

OP, if any of this resonates you can go down my posting history rabbit hole for more detail, feel free to post tangents here since your topic title has been answered

To everyone else, I'd appreciate any feedback on all the above - will move the convo to other / new threads if desired.

 

[SHB]

A few things:
• I own LS50’s, not the Meta’s (not that it matters)

• There is absolutely nothing about the LS50’s that necessitates an amp with a huge damping factor. Their back EMF, especially when not receiving signals below 170Hz, is negligible. The mid/bass driver is too small.

• I’m using a Parasound Halo A23 for the left & right and some Emotiva ICEpower mono amps for center and surrounds. They’re all 100 Watts and have no problem driving the LS50’s to ear splitting volume.

• I play bass though my home theater at levels that come close to bass rig SPL. The subs do all the heavy lifting.

• You’re mentioning a bunch of Class D amps that are more expensive than Topping B200 monoblocks ($600 each). How the B200 is out of your price range is beyond me.

 

[john61ct]

Thanks for those data points.

I'm keeping watch on second-hand pricing, $600 per channel is WAY out of my budget. Rather would incur a much longer delay than I'm willing.

 

[Rit]

Regret is a funny thing, saying something is out of budget. waiting a other month or two is far better.

 

[john61ct]

If it were that short no problem.

 

[rebbiputzmaker]

A few things:
• I own LS50’s, not the Meta’s (not that it matters)

• There is absolutely nothing about the LS50’s that necessitates an amp with a huge damping factor. Their back EMF, especially when not receiving signals below 170Hz, is negligible. The mid/bass driver is too small.

• I’m using a Parasound Halo A23 for the left & right and some Emotiva ICEpower mono amps for center and surrounds. They’re all 100 Watts and have no problem driving the LS50’s to ear splitting volume.

• I play bass though my home theater at levels that come close to bass rig SPL. The subs do all the heavy lifting.

• You’re mentioning a bunch of Class D amps that are more expensive than Topping B200 monoblocks ($600 each). How the B200 is out of your price range is beyond me.

Just saying that 170 is really much too high for subwoofer crossover. That’s not subwoofer territory. Driver positioning would be crucial now for coherency. Realistically 80 or 100 would be more in line for a normal crossover. And one more thing, high power amps don’t blow out speakers… it’s low power apps that are driven into clipping. I’ve never played my system so loud to blow out a speaker. Talking about in 50 years and dozens of different systems of all types. YMMV.

 

[101geo]

Just saying that 170 is really much too high for subwoofer crossover. That’s not subwoofer territory. Driver positioning would be crucial now for coherency. Realistically 80 or 100 would be more in line for a normal crossover. And one more thing, high power amps don’t blow out speakers… it’s low power apps that are driven into clipping. I’ve never played my system so loud to blow out a speaker. Talking about in 50 years and dozens of different systems of all types. YMMV.

If the mains are sitting on the subs does that still hold true? Sub drivers in the Revel Salon 2 cross at 150hz and my KEF reference 4's cross at 160hz.

 

[Sokel]

If the mains are sitting on the subs does that still hold true? Sub drivers in the Revel Salon 2 cross at 150hz and my KEF reference 4's cross at 160hz.

Not so simple. A 3-way (as a rig like that tries to replicate) needs to built from the ground up. And measured properly this way, I mean full spin.
At 80Hz we start to clearly hear male voices and up to 2khz we are in clear voice territory, men and women.

Do that wrong and everything goes off, specially proportions. And at a 3-way, anything that can go wrong, WILL go wrong, the complexity is not just about crossing it to the next
driver.

Edit: also, Salon crosses at around 500Hz-600Hz to it's 4" driver, it's a 4-way, way more complex.

 

[AkodoGilador]

Here's the distortion chart from Amir's review of the LS50 Meta:

I can definitely see why you'd want the cross-over to be at 150Hz - or even 200Hz, depending on the sub.

Alex

 

[SHB]

Just saying that 170 is really much too high for subwoofer crossover. That’s not subwoofer territory. Driver positioning would be crucial now for coherency. Realistically 80 or 100 would be more in line for a normal crossover. And one more thing, high power amps don’t blow out speakers… it’s low power apps that are driven into clipping. I’ve never played my system so loud to blow out a speaker. Talking about in 50 years and dozens of different systems of all types. YMMV.

I have 4 subs running in stereo and those subs are basically flat from 20-170Hz.

Also, as shown in the last post (above), the LS50’s distortion goes up precipitously below 170Hz.

There is no acoustic law keeping stereo subs from being properly used in any frequency range they can cover.

Bottom line: anyone who posts here would love my system if they heard it.

 

[john61ct]

The area above "true subwoofer" range (70-80Hz where localization / directionality largely goes away)

may require speakers specifically designed for "mid bass reinforcement".

There are SOME drivers that can both deliver SPL up past 200Hz and ALSO down below the 40-50Hz range but not many.

I am looking for such in my DIY "basstands" project, so any reco's welcome.

The options OTS I think are very rare, if I was made of money I'd just buy Rythmik FM8s.

Yes such mid bass modules need to be co-located with your LS50s

A fair bit of measurement / experimentation will be needed, where to crossover, how much overlap, phase/delay and room mode issues

especially if a "true sub" also needs integrating, placement for that will have huge consequences on the latter.

Most people say putting a quality DSP unit in charge of all crossovers, using that also for EQ and room correction will make things much "easier".

This adds to the cost of course. Just mucking about and getting it to "sound good" with your music, for your ears might be good enough for you, but not what this website usually advocates.

 

[john61ct]

passive crossovers, especially ones that low, waste a ton of amp power.

Isn't that only true for the type that works at high-level speaker signals, after the amp output?

The Harrison Labs inline units are passive but work at line level, just before the power amp inputs.

I realize their fixed HPF crossover point (100/150/200Hz) may vary a little based on the amp input impedance

but I figure so long as the active LPF controlling the MBM below is (continuously) variable not stepped, that can effectively handle the blending point.

 

[SHB]

I did pro sound for bands for over a decade. I design loudspeakers for a hobby and I’m a musician.

My Rythmik L12 subs are flat from 170Hz down to 20hz and I use two pairs of them stacked under the left and right speakers in my home theater. On top of music and movies, I also play bass through my system and up mix it to surround.

I did work as a recording engineer for a year, but really hated having to listen to most of the music that came through the studio.

Also, I studied physics at Penn State.

My home theater is set up as a LEDE (live end/dead end) room and it’s superior to any listening space I’ve ever heard.

With the LEDE set up and the odd, U-shaped room geometry, I was very happy to find that the room doesn’t have one bass mode. I can use the stacked subs as speaker stands for the front LS50’s with absolutely no adverse effect to the linearity of the low end.

I have a true 20-20kHz system that can cleanly play louder than is safe to listen to for longer than 15 minutes.

Walking the circuitous route from the first floor down into my basement theater, the low end only gets steadily louder. Again, not a room mode to be heard.

I could run Dirac Live, but there is really nothing to correct. It’s incredible.

Unfortunately, my house won’t allow me to set up an area for a CNC machine so I can mill my own speaker cabinets.

This system will more than do for now. I’ve heard Meridian DSP8000’s and my system at as good in the bass and really, really close in the mids and treble at high volume.

Oh, yeah, forgot to mention that a mega-church wants to talk to me about the possibility of doing live and studio recording for them. Haven’t talked money so that could be an issue.

So, I know way more than you about the science and the practical application of audio. I may have forgotten more about it than you actually know and I’ve forgotten very little on the subject.

 

[Sokel]

I did pro sound for bands for over a decade. I design loudspeakers for a hobby and I’m a musician.

My Rythmik L12 subs are flat from 170Hz down to 20hz and I use two pairs of them stacked under the left and right speakers in my home theater. On top of music and movies, I also play bass through my system and up mix it to surround.

I did work as a recording engineer for a year, but really hated having to listen to most of the music that came through the studio.

Also, I studied physics at Penn State.

My home theater is set up as a LEDE (live end/dead end) room and it’s superior to any listening space I’ve ever heard.

With the LEDE set up and the odd, U-shaped room geometry, I was very happy to find that the room doesn’t have one bass mode. I can use the stacked subs as speaker stands for the front LS50’s with absolutely no adverse effect to the linearity of the low end.

I have a true 20-20kHz system that can cleanly play louder than is safe to listen to for longer than 15 minutes.

Walking the circuitous route from the first floor down into my basement theater, the low end only gets steadily louder. Again, not a room mode to be heard.

I could run Dirac Live, but there is really nothing to correct. It’s incredible.

Unfortunately, my house won’t allow me to set up an area for a CNC machine so I can mill my own speaker cabinets.

This system will more than do for now. I’ve heard Meridian DSP8000’s and my system at as good in the bass and really, really close in the mids and treble at high volume.

Oh, yeah, forgot to mention that a mega-church wants to talk to me about the possibility of doing live and studio recording for them. Haven’t talked money so that could be an issue.

So, I know way more than you about the science and the practical application of audio. I may have forgotten more about it than you actually know and I’ve forgotten very little on the subject.

Credentials are nice and there's absolutely no reason to doubt that you like your sound.
But we're more used to measurements here, so I guess you have your spins to show.

As for the Meridian comparison, unless some elaborate set-up was used to level-match, place-match, blind, etc is close to meaningless as a text here.
But, again, glad you like your sound, it's your ears after all.

 

[rebbiputzmaker]

I did pro sound for bands for over a decade. I design loudspeakers for a hobby and I’m a musician.

My Rythmik L12 subs are flat from 170Hz down to 20hz and I use two pairs of them stacked under the left and right speakers in my home theater. On top of music and movies, I also play bass through my system and up mix it to surround.

I did work as a recording engineer for a year, but really hated having to listen to most of the music that came through the studio.

Also, I studied physics at Penn State.

My home theater is set up as a LEDE (live end/dead end) room and it’s superior to any listening space I’ve ever heard.

With the LEDE set up and the odd, U-shaped room geometry, I was very happy to find that the room doesn’t have one bass mode. I can use the stacked subs as speaker stands for the front LS50’s with absolutely no adverse effect to the linearity of the low end.

I have a true 20-20kHz system that can cleanly play louder than is safe to listen to for longer than 15 minutes.

Walking the circuitous route from the first floor down into my basement theater, the low end only gets steadily louder. Again, not a room mode to be heard.

I could run Dirac Live, but there is really nothing to correct. It’s incredible.

Unfortunately, my house won’t allow me to set up an area for a CNC machine so I can mill my own speaker cabinets.

This system will more than do for now. I’ve heard Meridian DSP8000’s and my system at as good in the bass and really, really close in the mids and treble at high volume.

Oh, yeah, forgot to mention that a mega-church wants to talk to me about the possibility of doing live and studio recording for them. Haven’t talked money so that could be an issue.

So, I know way more than you about the science and the practical application of audio. I may have forgotten more about it than you actually know and I’ve forgotten very little on the subject.

OK, so to clarify the confusion, regarding your opinion and what other people are saying, let’s make this clear. You are really not using your subwoofers as subwoofers! You are really making them part of your speaker system as they are adjacent to the LS 50 basically a woofer of the LS 50. Let’s say like a homemade blade system. That’s different. When most people think of subwoofer they’re putting it anywhere in the room depending on room modes maybe you place it to help alleviate them, etc. etc.. that might make this whole conversation more clear for everybody. It might make you understand better why people are sort of questioning what you were saying. Is that better??

 

[rebbiputzmaker]

I did pro sound for bands for over a decade. I design loudspeakers for a hobby and I’m a musician.

My Rythmik L12 subs are flat from 170Hz down to 20hz and I use two pairs of them stacked under the left and right speakers in my home theater. On top of music and movies, I also play bass through my system and up mix it to surround.

I did work as a recording engineer for a year, but really hated having to listen to most of the music that came through the studio.

Also, I studied physics at Penn State.

My home theater is set up as a LEDE (live end/dead end) room and it’s superior to any listening space I’ve ever heard.

With the LEDE set up and the odd, U-shaped room geometry, I was very happy to find that the room doesn’t have one bass mode. I can use the stacked subs as speaker stands for the front LS50’s with absolutely no adverse effect to the linearity of the low end.

I have a true 20-20kHz system that can cleanly play louder than is safe to listen to for longer than 15 minutes.

Walking the circuitous route from the first floor down into my basement theater, the low end only gets steadily louder. Again, not a room mode to be heard.

I could run Dirac Live, but there is really nothing to correct. It’s incredible.

Unfortunately, my house won’t allow me to set up an area for a CNC machine so I can mill my own speaker cabinets.

This system will more than do for now. I’ve heard Meridian DSP8000’s and my system at as good in the bass and really, really close in the mids and treble at high volume.

Oh, yeah, forgot to mention that a mega-church wants to talk to me about the possibility of doing live and studio recording for them. Haven’t talked money so that could be an issue.

So, I know way more than you about the science and the practical application of audio. I may have forgotten more about it than you actually know and I’ve forgotten very little on the subject.

Just to explore a bit more, having over 50 years of building speakers, electronics, etc. In my opinion, which might not matter much, instead of having all those subwoofers, you might be better off building a solid cabinet use a high-quality 7 or 8 inch maybe a purifi and then actually cross the LS 50 over even an octave higher. Then bring your subs in say 80 below. Just a thought.

 

[terryforsythe]

Isn't that only true for the type that works at high-level speaker signals, after the amp output?

Yes, that is true.

The Harrison Labs inline units are passive but work at line level, just before the power amp inputs.

I realize their fixed HPF crossover point (100/150/200Hz) may vary a little based on the amp input impedance

An active crossover implemented using a good DSP unit will work better for line level inputs for numerous reasons:

1. DSP will give you the ability to set the crossover frequency to virtually any frequency you want.

- 150 and 200Hz are a little high for a subwoofer/satellite configuration. 100Hz MAY be OK if the crossover slopes are steep enough (at least 4th order), but it may not be optimal. You really won't know until you take measurements of your system in your room and listen. In my experience, the ability to measure, tune, listen and repeat is invaluable when trying to optimize the sound quality of a system in a real world living space.

2. DSP will give you the ability to adjust crossover slopes and crossover topology. See the note immediately above pertaining to tuning.

3. DSP will give you the ability to adjust the time delay of the speakers and/or subwoofer. If your subwoofer already has time delay adjustment that may be adequate, though.

4. DSP will give you the ability to apply parametric equalization for room correction. If your DSP unit has room correction built in (e.g., Dirac Live), that makes it even easier.

All that being said, if simplicity is of utmost importance to you and you have no interest in optimizing the system to get its best performance, and the Harrison Labs unit is cheap enough, it may work for you. But, at that point I would just get a pair of full range tower speakers and be done with it.

 

[john61ct]

Touchy much?

That's all wonderful, but I don't have such resources. I wasn't challenging your expertise, just asking a simple question and proposing a simple hypothesis.

Any chance you could just address my post?

I did pro sound for bands for over a decade. I design loudspeakers

 

[john61ct]

Thanks for actually addressing my text.

Yes I am aware a good DSP may well be superior, but 1. I can't afford a good one yet, may be years away and 2. my preference / bias is for analog simplicity especially for my LS50s channel, at least until measurements show more sophistication is required.

The LS50s are also the given in my system for now.

Yes, that is true.

An active crossover implemented using a good DSP unit will work better for line level inputs for numerous reasons
...
if simplicity is of utmost importance to you and you have no interest in optimizing the system to get its best performance, and the Harrison Labs unit is cheap enough, it may work for you. But, at that point I would just get a pair of full range tower speakers and be done with it.

> 150 and 200Hz are a little high for a subwoofer/satellite configuration.

Apparently thereabouts is the right place for LS50s specifically, many say even higher.

You are correct that testing is needed. If 120Hz is high enough I can try using my Outlaw ICBM-1 to handle more of the crossovers.