J.B.L. Pro Cinema 3677 - at home!

indus

Distinguished Member
As always it's so refreshing to get a balanced opinion from Jags.

Sponsors who make claims in orders of magnitude that run into 'light years' should take note and feel a little ashamed imho.
 

mojogoes

Remembered (1961-2016)
Just to put some sort of balance on the performance of the jbl 3677's is that although they are not harsh especially on the end of some good amplification like some folk would have you believe! but they are somewhat limited in the hf areas and is the only real reason my friend decided to go with the Sk2 3300c and the Sam 1LF Sam 2hf for LR duties.

So if you look at the frequency specs of both the 3677's and them of the Sk2 3300's you will see quite a large differential in hf response?
 

sammy the squid

Distinguished Member
Just having a read of two Xtz/JBL posts a bit further up the thread.

I think the nail is hit on the head once one acknowledges that each speaker is intended for a different application. As such, both are decent performers, but it really comes down to the application for which a speaker is required. In some scenarios the XTZ will be more appropriate, in others the JBL.

In circumstances where it could go either way, have a listen to both and establish which is appropriate based on the sound you prefer because past a particular point it's not about which is better, but which is preferred.

Right, I'm off to watch Deadpool 4K, have a goodnight folks :thumbsup:
 
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PhilChap

Active Member
My room is now plastered out. The size is coming up at approx. 5.5 x 3.3 x 2.2 high. Very interested to know what treatment would be recommended to go with the 3677. Only one door 1.5m from the front right corner. No windows. I may be able to squeeze subs in between the JBL's, do they need room either side or will they be fine snug behind AT screen?
 

Smurfin

Distinguished Member
Very interested to know what treatment would be recommended to go with the 3677.

You need to understand the room in order to answer that question. "Treatment" isn't something to be taken lightly nor is it the same for each room; but as a starter, I'd be looking at treating first and second reflection points as a minimum. If you don't know what those are you have some reading ahead of you :) (but fun reading).
 

Smurfin

Distinguished Member
Just to put some sort of balance on the performance of the jbl 3677's is that although they are not harsh especially on the end of some good amplification like some folk would have you believe! but they are somewhat limited in the hf areas and is the only real reason my friend decided to go with the Sk2 3300c and the Sam 1LF Sam 2hf for LR duties.

So if you look at the frequency specs of both the 3677's and them of the Sk2 3300's you will see quite a large differential in hf response?

I'm over 40 so probably can't hear anything above the JBLs rolloff anyway :)
 

PhilChap

Active Member
You need to understand the room in order to answer that question. "Treatment" isn't something to be taken lightly nor is it the same for each room; but as a starter, I'd be looking at treating first and second reflection points as a minimum. If you don't know what those are you have some reading ahead of you :) (but fun reading).

I have had plenty of time to read but no chance to put into practice :). I intend treating first reflection, screen wall and rear. It seems a complete minefield but I do not want to become too obsessed. I would like to know what material jag was using in the screen wall in the above install. My room is currently a blank canvas Home Cinema rebuild
 

mojogoes

Remembered (1961-2016)
Hi Phil will you be building a false front screen / lcr speaker wall and do you intend to panel over any of the other walls , a good place to start for acoustically treating the amount of bass that will be generated in your room is to fit four corner bass traps from floor to ceiling plus the front soffits and floor and the same at the rear if you can!

If you are going to panel each wall any way you can incorporate the acoustic material laying it flat behind an acoustic panel just in the corners where the acoustic material has been fit as its pretty expensive boarding.

The other way is just positioning these bass traps in each corner
upload_2016-5-16_7-37-16.jpeg

Plus this type of soffit trap
images


On the rear wall
images
which you can also fit some diffusers if youve got something like 3/6' behind you.
 

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PhilChap

Active Member
Hi Phil will you be building a false front screen / lcr speaker wall and do you intend to panel over any of the other walls , a good place to start for acoustically treating the amount of bass that will be generated in your room is to fit four corner bass traps from floor to ceiling plus the front soffits and floor and the same at the rear if you can!

If you are going to panel each wall any way you can incorporate the acoustic material laying it flat behind an acoustic panel just in the corners where the acoustic material has been fit as its pretty expensive boarding.

The other way is just positioning these bass traps in each corner View attachment 715746
Plus this type of soffit trap
images


On the rear wall
images
which you can also fit some diffusers if youve got something like 3/6' behind you.

The front will be like the picture Jag posted above. 3 JBL 3677 sat behind AT screen. Seating will be about 3.5m back leaving about 1.5m to rear wall.
 

Smurfin

Distinguished Member
No not when your as old as us! its like yesterday:D................I think i may have just bought those 850's lets see if there as bad as you first made out;)

I ended up buying a set a few years later! Not bad speakers but very sensitive to room and electronics.

Phil - are you going to fill the void behind the screen?
 

mojogoes

Remembered (1961-2016)
So if you start with the basic four corner bass traps and first and second reflection point plus some rear wall absorbers / diffusers and the take some REW measurements to see where your at before any eq is added I think you can't go far wrong.

If you want to be more anal about it all you could run REW before putting anything in there to see what sort of fr your getting but imo the first option is where most people want to be.
 

mojogoes

Remembered (1961-2016)
I ended up buying a set a few years later! Not bad speakers but very sensitive to room and electronics.

Phil - are you going to fill the void behind the screen?

The void would best need filling with 60kg/m 100kg/m rock wool at 50/100 mm
 

PhilChap

Active Member
The void would best need filling with 60kg/m 100kg/m rock wool at 50/100 mm

Thats a good starting point, what do I cover this with?
 

mojogoes

Remembered (1961-2016)
Thats a good starting point, what do I cover this with?

You could use either knauf Rs60 50 mm or 100mm thickness or knauf Rs100 at the same thickness's again , depending on how much space there is you've got behind there

The Rs100 is more dense and will absorb more ! Are you planning to place your sub(s) in this wall to or Behind lin front of it?
 

PhilChap

Active Member
You could use either knauf Rs60 50 mm or 100mm thickness or knauf Rs100 at the same thickness's again , depending on how much space there is you've got behind there

The Rs100 is more dense and will absorb more ! Are you planning to place your sub(s) in this wall to or Behind lin front of it?

I may sandwich a sub either side of the center behind the screen. I am really wanting the screen to come very low to the floor so would prefer this rather than sat below screen. I could place just forward of the screen as another option. I am thinking either one center rear or one in each rear corner too longer term.
 

mojogoes

Remembered (1961-2016)
Either would work and at the rear you would get that close field sub tactile effect So you now set to go Phil and have you now got all your funds in place for this new project also buy plenty of green acoustic glue / sealer
 

cdy2179

Active Member
right.jpg


My 3677 after XT32 EQ (shown with dynamic EQ on) are flat to 15k or so. That's high enough where a higher response is really irrelevant IMO. I've owned many speakers and the top end on the 3677 in a treated room, properly setup and eq'd is fantastic and "alive".
 

cdy2179

Active Member
The scale can be seen on the left. 5db per division. 1/6 smoothing. I don't smooth when I EQ subs but I'm sure you know smoothing must be applied on the mains to read the response.
 

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