JBL 705P / 708P

[jhaider]

I'm thinking of building a centre channel based en 705/708 compression driver and two boomers from 705 with active crossover. I made a really quick photoshop of the idea. Off course I would put the horn horizontally. What do you think?
View attachment 352796

Absolutely not, under any circumstances.

 

[Rahan]

Well you guys seem to think that's not a good idea. But could you give arguments? Obviously a 708 doesn't fit under my screen it would have been too easy . I don't want to put it on the side. A single 705 won't match my front 708 in spl capabilities.

 

[Rahan]

So for you guys a jbl scl-6 is crap?

 

[GXAlan]

Do you need more SPL than can be achieved with the 705? Vertical horns are used in the Synthesis Array so you could see how well that actually works in your own setup. The Array 880 was tested here and gives a lot of SPL.

Well you guys seem to think that's not a good idea. But could you give arguments? Obviously a 708 doesn't fit under my screen it would have been too easy . I don't want to put it on the side. A single 705 won't match my front 708 in spl capabilities.

If you want high SPL, what about the Meyer Sound Amie?

 

[Rahan]

Thank you. I've checked the 880 array review and this convinced me that this is the kind of speaker I need. My set up is only a double seat 3 m away from the future Center speaker. So the narrow horizontal directivity is no issue. And the 705 won't play loud enough. The meyer sound seems outstanding but expensive. I thought it could be cost efficient and fun to build some thing.

 

[beefkabob]

MTM is generally just bad because the mids interfere with each other and create a comb filter effect on the horizontal. If you think that you can do better than professional speaker engineers on your own, well, have fun, but now you have your answer and your explanation several times over.

 

[Tom C]

I am in no way any kind of expert to be advising on the technical merits and feasibility of one design vs. another. But as a casual enthusiast…
If you trim the 708’s by -7dB, they should match the output of the 705’s, going by what is reported on the spec sheets supplied by JBL. They will be matched in timbre, as you already know, since you have 705 and 708 in your system already. You could still run the 708’s full power when playing two-channel material.
Any chance you have room to move your subwoofer more to one side, and make room for a 708 underneath the screen? You’d need a stand of the correct height for the 708, but if it were my room, this would probably be my first choice.
That C211 is a very interesting speaker, with 15-in woofer. The drawback is that it is more limited in how you can position it on the wall. It has to be behind the screen because of the design of the dispersion characteristics, which is OK if you have a perforated screen, but won’t work for a panel. As far as cost compared to 70x series, C211 doesn’t have built-in power supply, amplifier, EQ, and ADC, but 70x has all of that, plus a pass through to allow daisy chain to the next speaker when using AES, and an Ethernet connector to allow for remote configuration of the speaker. That’s a ton of functionality that will be added cost when replicating with C211.

 

[Rahan]

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MTM is generally just bad because the mids interfere with each other and create a comb filter effect on the horizontal. If you think that you can do better than professional speaker engineers on your own, well, have fun, but now you have your answer and your explanation setimes over.

Thank you but keep in mind that I am not your child. If my question bothers you, don't answer.

 

[Rahan]

I am in no way any kind of expert to be advising on the technical merits and feasibility of one design vs. another. But as a casual enthusiast…
If you trim the 708’s by -7dB, they should match the output of the 705’s, going by what is reported on the spec sheets supplied by JBL. They will be matched in timbre, as you already know, since you have 705 and 708 in your system already. You could still run the 708’s full power when playing two-channel material.
Any chance you have room to move your subwoofer more to one side, and make room for a 708 underneath the screen? You’d need a stand of the correct height for the 708, but if it were my room, this would probably be my first choice.
That C211 is a very interesting speaker, with 15-in woofer. The drawback is that it is more limited in how you can position it on the wall. It has to be behind the screen because of the design of the dispersion characteristics, which is OK if you have a perforated screen, but won’t work for a panel. As far as cost compared to 70x series, C211 doesn’t have built-in power supply, amplifier, EQ, and ADC, but 70x has all of that, plus a pass through to allow daisy chain to the next speaker when using AES, and an Ethernet connector to allow for remote configuration of the speaker. That’s a ton of functionality that will be added cost when replicating with C211.

I'll try with a 705p but I like to watch movies with quiet immersive loudness. If a 705 can handel it, so bit, (that would be awsome). But i doubt it. The C211 seems nice but definitely too big If a 708 doesn't fit, imagine a C211. Moving the sub somewhere else could be an option that would make things easier. But in my room it's not that a easy thing to do. Last, in My HT i use passive version of the 7xx. I was full AES with my Dynaudio core systeme but I wanted to go passive. I'll also check the 880 array option (mesurements are fine to me.)

 

[Sal1950]

I'll try with a 705p but I like to watch movies with quiet immersive loudness. If a 705 can handel it, so bit, (that would be awsome).

I don't think you'll be disappointed.
The center channel in movies is mainly used for dialog and to slightly support some of the more dynamic information of the source. The rest of the base channels are more important along with the LFE/subwoofers for that impact.

 

[GXAlan]

Thank you. I've checked the 880 array review and this convinced me that this is the kind of speaker I need. My set up is only a double seat 3 m away from the future Center speaker. So the narrow horizontal directivity is no issue. And the 705 won't play loud enough. The meyer sound seems outstanding but expensive. I thought it could be cost efficient and fun to build some thing.

You might consider getting an Array 880 and running it with a HypeX amp?

I'll try with a 705p but I like to watch movies with quiet immersive loudness. If a 705 can handel it, so bit, (that would be awsome). But i doubt it. The C211 seems nice but definitely too big If a 708 doesn't fit, imagine a C211. Moving the sub somewhere else could be an option that would make things easier. But in my room it's not that a easy thing to do. Last, in My HT i use passive version of the 7xx. I was full AES with my Dynaudio core systeme but I wanted to go passive. I'll also check the 880 array option (mesurements are fine to me.)

Unless you are needing the full 105 dB at 2 m, you’ll be fine with the 705p. It is rated at 101 dB @ 1m!

There is a used Array 880 on eBay right now from a reputable used dealer. Note that the soft touch plastics get sticky with age and this is reported as being sticky…

 

[Rahan]

You might consider getting an Array 880 and running it with a HypeX amp?


Unless you are needing the full 105 dB at 2 m, you’ll be fine with the 705p. It is rated at 101 dB @ 1m!

There is a used Array 880 on eBay right now from a reputable used dealer. Note that the soft touch plastics get sticky with age and this is reported as being sticky…

Definilely I'll try a 705 as a centre channel as soon as my minidsp HTx arrive. I'll let you know if it does the job. The 880 array is really tempting. I love the way it looks.

 

[catastrofe]

Contemplating a pair of 708P in a dual purpose music/"theater" 2.2 setup. Currently using a Lyngdorf TDAI-1120 feeding a pair of BMR Monitors and dual Rythmik F12SE subs. I use Roon exclusively for music playback and eArc out of my LG TV.

I'm struggling with a system design that would incorporate the subs, 708s, and eArc while still giving me system-wide room correction. I realize the TDAI-1120 won't work in this scenario.

Would love to hear some suggestions on how to accomplish this. While I can run correction via Roon using Convolution filters, that won't address TV audio.

 

[BDWoody]

Would love to hear some suggestions on how to accomplish this. While I can run correction via Roon using Convolution filters, that won't address TV audio.

I use the preamp outputs of a Denon receiver with mine. There are quite a few good receivers that could work well.

 

[catastrofe]

I use the preamp outputs of a Denon receiver with mine. There are quite a few good receivers that could work well.

Thanks.

I use a newer Apple TV 4K (HDMI output only), so I'm wondering if I could run HDMI to the TV then optical out from the TV to a MiniDSP SHD to handle room correction. I believe the SHD has enough outputs for two subs and the 708s, along with a network connection for Roon.

 

[Rahan]

Contemplating a pair of 708P in a dual purpose music/"theater" 2.2 setup. Currently using a Lyngdorf TDAI-1120 feeding a pair of BMR Monitors and dual Rythmik F12SE subs. I use Roon exclusively for music playback and eArc out of my LG TV.

I'm struggling with a system design that would incorporate the subs, 708s, and eArc while still giving me system-wide room correction. I realize the TDAI-1120 won't work in this scenario.

Would love to hear some suggestions on how to accomplish this. While I can run correction via Roon using Convolution filters, that won't address TV audio.

Minidsp flex ht x. You could do exactly what you want. And you can still upgrade to 5.2 later if you want.

 

[catastrofe]

Minidsp flex ht x. You could do exactly what you want. And you can still upgrade to 5.2 later if you want.

Thanks.

The Flex HTx would handle eArc from my TV, but it doesn't have a network connection so it won't work with Roon over my network (my core is in another room, streamed wirelessly to a network extender then via ethernet to my audio system).

Not sure if you saw my follow-up post about using the MiniDSP SHD with an optical connection to my TV in lieu of eArc. Do you think that would work?

 

[Tom C]

The Lyngdorf has L&R analog line out, which the owner manual says can be used to drive two subs. I assume you have the version of F12SE that does not have outputs (there is a version available that does have output connectors). If so, you may be able to contact Lyngdorf or your dealer to ask if it is OK to use a Y-connector on each to drive the monitor and sub pair. If your F12SE version does have the outputs, you wouldn’t need the splitter.
The 708P has 12 “room EQ” filters, and an additional 8 “user EQ” filters, plus a “bass management” high-pass filter. I don’t know the type of room correction you’d like to do, but for me 20 filters is more than double the number I’d ever use on the monitor in any circumstance. The subs have their own filters available. Plus whatever is built into the Lyngdorf, which presumably is adequate for the job.

 

[Tom C]

You have optical in on the Lyngdorf. You can test right now with that to see if it works. If it does, there’s no reason to think it wouldn’t work with a miniDSP.

 

[catastrofe]

The Lyngdorf has L&R analog line out, which the owner manual says can be used to drive two subs. I assume you have the version of F12SE that does not have outputs (there is a version available that does have output connectors). If so, you may be able to contact Lyngdorf or your dealer to ask if it is OK to use a Y-connector on each to drive the monitor and sub pair. If your F12SE version does have the outputs, you wouldn’t need the splitter.
The 708P has 12 “room EQ” filters, and an additional 8 “user EQ” filters, plus a “bass management” high-pass filter. I don’t know the type of room correction you’d like to do, but for me 20 filters is more than double the number I’d ever use on the monitor in any circumstance. The subs have their own filters available. Plus whatever is built into the Lyngdorf, which presumably is adequate for the job.

Thanks Tom.

My subs do not have the pass-through. I did think about splitting the pre-outs of the 1120 and sending full signals to both the subs and 708s, letting each filter out respective frequencies, but that would negate the use of Lyngdorf's Room Perfect correction software and seems like it would present an integration challenge vs a singular solution.

Definitely worth considering if nothing more "elegant" presents itself.