JBL 3677

[Music Lover]

This makes me wonder if any of the JBL surround speakers have the same magic as the 3677. Could they be used in a small system as bookshelf speakers?

I've owned the JBL 8330a and 8340a. I tested in two channel and both were worthy of being a boat anchor IMO. I couldn't sell them fast enough!

I bought a used pair of 8340 to my son and they are quite good. I think the a-model is a later version.

[cdy2179]

Yea the A model 8340A has a plastic enclosure. The older 8340 is wooden. I test my surrounds as mains for weeks before I'll use them as surrounds.. I'm really picky. The A model was very harsh. I tested it in two channel in hopes it would make a good front end for HT. It was one of the worst speakers I've owned. The 8330a wasn't as harsh but it just sounding tiny and cheap. If you want something that mops the floors with them and many mains I'd look at the Volt 10lx. It's the best surround I've owned and puts many of the my mains to shame. I have 10 of them and they keep up with my 3677s without a problem. Being coaxial it's perfect for Atmos (even IB with no enclosure) with an even dispersion 360 degrees.

http://www.diysoundgroup.com/coaxial-sp ... -10lx.html

[Charlie1]

Hi
I have made a recording using my iPhone so quality is of course really bad but it might give you an idea of how it sounds. On all these tracks the bass response is my room is quite heavy.

You can download the clip here:
https://dl.dropboxusercontent.com/u/352 ... G_0005.MOV

Not sure I ever got around to listening to this properly. Thanks for posting. It's really useful to hear a cross section of music. I was thinking of getting 242 mark 1s at some point but I think I just need to be brave and go for these.

Your system sounds wonderful by the way. Easily one of the best I've heard using these video clips.

[fatjulio]

New 3677 owner here. I've only had them hooked up for a couple of days, but really like them. So musical and involving! They're only on the floor, no stands yet. I've got 3 of them for the front of a theatre system, and music.

Just started playing with the subwoofer configuration. I've got a K345 and using a Kisto for analogue bass management. Best result so far is K345 out of phase (to be in phase) and not crossed over, but taking a feed from the left and right. Using the K345's internal filter set to it's low pass to 55Hz (it's lowest) and 6db boost below 30Hz and reducing the gain, to get a steeper rolloff to the 3677's, which are not bass managed at all.

I used a calibration DVD to play a frequency sweep to find out what the 3677's can do. There was audible output in the 40-50Hz range and went up from there. For comparison, I've replaced 242's, which started in the 30-40Hz range. Mine have only a few hours use, so hopefully will get better.

[fatjulio]

Been playing some more. Perhaps better crossing over the K345 in the Kisto with the 3677's, I hadn't tried it with the phase inversion. The Kisto's analogue crossover is only at 120Hz.

I'm assuming I need the phase inversion to get the phase relationship correct because the sub has group delay as it's an active sub? So using a passive one (a JBL) would alleviate this?

[lejonklou]

Have you tried listening without phase inversion, fatjulio?

[fatjulio]

Yes, I started with the phase not inverted, and that has less bass. I had the same issue with the 242's. I'm going back to not using the crossover, just the L/R feed "helping" the 3677's. The crossover setup was muddying the middle, losing some spark and dynamics. The helping setup just adds some down the bottom without too much interference.

[ThomasOK]

Just a little update that Linnofil appears to have finalized his design of the stands and has started to deliver them to several members. I have been told privately by a few owners that it makes a huge improvement (as would be expected). He is making a set for me with a small design change - it has no outriggers or extensions to the left and right of the speaker. These would have been impossible to fit in my room. Instead the sides of the stand end flush with the sides of the speakers. My understanding is that he had already tried it and found with another small change or two there was little musical difference. He sent me a drawing and it looked perfect. I hope they will be on their way here soon!

An additional piece of news is that I sold my ATCs after 10 years of musical duty. It was hard to let them go but the JBLs are just plain better. Debbie says she thinks it was the first mistake I have made in upgrading my system. But she is heavy into bass and misses the low end of the ATCs. I intend to prove her wrong and fully expect that the stands, the external crossover mod and a subwoofer will accomplish that task easily. Speaking of subwoofer, as the ATCs are gone I will be ordering the JBL 4645C today. I already have a temporary crossover that I think will work well (temporary as until a few of us can convince Fredrik to make one - something not likely to happen in the near future as he is up to his eyeballs in his next product design). This should be fun!

[Music Lover]

Linnofil visited my yesterday to deliver the stands.
The 3677's is now SOOOO much better it's hard to believe!
Every aspect is improved.
That said, the 3677's on piles of books were already wonderful.

The stands is a MUST HAVE. The performance is at-least twice as good, if now more.
Linnofil, I thank you from the bottom of my heart :)
These stands going to be a huge seller together with the 3677.
I never heard anything remotely close - this is live...the real deal...just music. It simply flows.
Nobody that hear these speakers going to resist. They are a must have.


We also played with the 4645C sub positioning and found a performance peak at 4.7cm over the floor. Getting more books and going to explore higher heights in a few days.
Made a fast tuning the other week and found a peak at 14'isch cm, but that was with a bunch of different books. To get a more stringent result, I need many books of exactly the same sort.
At this stage with just basic sub tuning, the performance is just slightly reduced compared with running the 3677 alone. So I'm fully convinced the sub going to be great once tuned.
And then...Linnofil has a sub stand in the making, and then we all know how much the performance is improved don't we? *grinnning*

The sub is very fast and articulate. And it add the bass that a bass lover and previous active Isobarik, Keltik and Komri owner desire.


This going to be a fabulous year!
Stay tuned :)

[ThomasOK]

Great report, now I am even looking forward more to the stands. I will certainly need to get the sub stand when it is ready. I did order my sub yesterday and was told it was in stock so I will likely have it next week to early the week after. After owning Isobariks from 1980, going Aktiv in the mid-90s, and then getting the big ATCs in 2006 I am also used to powerful and deep bass so I believe the 4645C will be just the ticket. I am hoping that it is not too sensitive to position, other than height, as I pretty much only have one place where it will fit - and there only barely. I will have a little room for side to side movement (very little) but it will have to be very close to the wall behind it.

I am expecting it to be a fabulous year as well. Not only in terms of how this system is sounding and will sound. I am also very pleased to announce that Fredrik will be coming to the US again in October!

[Music Lover]

Great that you get the sub fast, let's both test out the optimum height as Linnofil need that info to design the sub stand.

[cortina]

Regarding height but appearing off topic..
I just got back from Barcelona where I re-visited Sagrada Familia - highly recommended btw as much has been done inside compared to just a few years back.
Anyway, Gaudí, the architect, was a true perfectionist working in an engineering way and realized he needed to study both music and acoustics as he was building a church. He then, almost 100 years ago, came to the conclusion that the balcony for the huge choir should be at 1/3 of the height of the "ceiling". Acc to the guide this has later been concluded to be a general acoustical "optimum".

So, not knowing if this is really a general rule,
it made me curious. Is the optimum speaker height not affected by the height of the ceiling? Naturally, this would create difficulties in terms of multiple stand versions, but would a 2,2 m ceiling have the same optimum stand height as e.g. a 2,7 m ceiling?
Or is the height of the tweeter (?) vs listening/ear position the only factor for a speaker?

[ThomasOK]

Interesting thought. Personally I think it would be more the case when producing music in a live space than reproducing it in the home, but I could be wrong. There are speaker manufacturers who claim that the best place for their speakers is a third of the way into the room, likely based on the same understanding of acoustics. However, I have never found them to be the most musical in those positions.

[cortina]

That would certainly make (keep) things simple.
On the other hand doesn't Linn's Exakt indata include a height measurent. Presumably for resonance reasons.
But a quick search on the internet also gave that the human brain (people in a choir at least) needs a certain delay of sound to process the information.
Otherwise, perhaps a certain speaker position in the room with a std stand leads to a sub-optimum if the height is not optimal vs ceiling height? Then that suboptimum may often be very similar to the true optimum? And perhaps the maybe is almost an always.

[matthias]

Supposing the acoustic center of the 3677 is in the middle between woofer and tweeter and considering the height of Linnofils excellent stands, the perfect ceiling height would be 2,6 m.

Matt

[ThomasOK]

Considering the standard height in many US houses is 8 feet, including in mine, 2.6 meters or about 8.5 feet is pretty close!

[matthias]

Considering the standard height in many US houses is 8 feet, including in mine, 2.6 meters or about 8.5 feet is pretty close!

Yes, mine is 2,85m, deviating from the optimum, but certainly ok.

Matt

[ThomasOK]

Well, it has been quiet on here for a little bit (lots of people on vacation likely has some effect) so lets stir things up a bit. I finally had a chance to start work on the external crossover mod. Even though I haven't completed the optimizations I can say that moving the crossovers to external wooden boxes with 1m split K400 going to the boxes and 2.48m K400 going to the drivers makes a significant improvement. Probably not as big as what people are saying about the stands but certainly worthwhile. I first converted one speaker and compared it to the other stock one and quite enjoyed the improvement - more musical, hearing further into what the musicians are doing, easier to follow musical threads - all good things. Just last night I modified the other 3677 but, since it was after midnight by the time I got the speaker back together I didn't have a chance to listen to it yet. Plus I have to do a couple of crossover A/Bs before I can put the stereo setup all back in place.

I moved the connectors to the back at a place between the two drivers and near the center (initially too near as it turned out I was drilling into a brace - oops!). Having now done this to both speakers I would reconsider the way I did it so hopefully some will learn form my mistakes. First off the back is too thick for the proper Deltrons banana sockets to fit through. The very metal tip will come through but there is no way to thread on the nut. In order to do that you have to drill a larger hole about half way in, one that the the nut will fit into so you can fasten the Deltrons in place. However, the place where I put the holes was directly across from the front baffle between the woofer and the horn. This made it a royal pain enlarging the holes and getting the Deltrons in place. So if you want to move the connections to the back I would recommend putting them directly across from the woofer opening so you can do this more effectively. I used two pieces of 3/4" mdf to seal off the original crossover plate hole, one bigger than the hole glued on the back of it and another one glued to that piece designer to fit snugly in the hole (which it didn't quite do so some wood filler will even things out). In doing this work I noticed that the black finish on the speaker is not a paint as I had thought but is a vinyl wrap so painting it is likely to be futile. If you don't mind it on the side it would likely be a lot easier to use a thinner board with the Deltrons on it glued to the back of the hole. The internal wiring is, of course, K400 soldered directly to the drivers and the Deltrons with Lejonklou solder at 677°F.

While inside these beasties I had to play around a bit, of course. So I have some information for all using these. It appears once again that somebody at JBL knows what they are doing. There are three phillips screws (although my PosiDriv 1 tip fit them quite well) that come from the factory tightened to something very close to 1.2Nm. Now I didn't check every single notch of possible adjustment over a wide range but I did try settings at .4, .6 , .8 and 1.4Nm and found 1.2Nm better than any of them. Testing further around the 1.2Nm setting I found 1.2+2 notches to be the most musical on my driver. Additionally the driver/magnet is threaded onto the horn. I have no way of finding an exakt torque with the driver but I did find it responded to different tightness of threading on. The best way I can think to describe it is that they are most musical with the fitting snug but not what I would call tight. You pretty much just want to nip it up, which is again how it comes from the factory.

Now a couple of questions. I understand placement is important on the crossover boxes (did anybody expect otherwise? is anything in Hi-Fi ever simple?). What have people found to work best? What have you found to be the best feet for them? I definitely want to play around with them a bit but so much else is going on around here it is hard to find time for these experiments. I haven't even got the subwoofer out of the box yet so the journey is just beginning!

[jlrchrds]

I haven't been on here, any hifi threads, in awhile. I'm still grooving with my Linn Exakt gear, but that said, this has to be one of the most interesting threads I've read in a very long time. I've been thinking about a second system again in my bsmt. Perhaps this with Lejonklou electronics, a Linn DS and LP 12 might be the bomb. I think what's most interesting to me is that I think of JBL being crap. I gotta say I'm extremely curious. I love the fact they are so efficient and honestly cheap. Jeff

[ThomasOK]

Well, between vacation and playing around with the crossovers it has been a month since I've had my speakers connected up in stereo. But this weekend I did have a couple of hours to play around with things and made some definite progress (despite having to spend most of the weekend dealing with my unruly yard). Someone had said that metal was not good to be around crossovers so I decided to experiment. After glueing wood rails into the boxes and notching them for some components that are close to the edge, I tried two ways of mounting the crossovers. I drilled holes and threaded them with stainless steel screws and then used the SS screws in one (since they are non-magnetic) and plastic screws on the other with plastic standoffs holding the boards up high enough on both. You can see in the photo below the one I started off with the SS screws. I torqued the SS screws to .4Nm, which works well with many circuit boards, and the plastic screws close to that (although some didn't like that much torque). Then I listened and found that the one with the SS screws was more musical. So I changed the other one to the SS screws.

Then came torque testing and I found the best torque for these crossovers to be .4Nm +4.5 notches. Then I needed to hold the tops closed so I used some Linn felt damping strips on the bottom of the case lip and held them closed with rubber bands. I thought the rubber bands might make good feet but I was not happy with the musicality so I put four metal washers under the corners and was much happier. So that is the way they sit for now. It isn't ideal as the four corners are not all solidly connected to the floor - there is some rocking. But after configuring both crossovers the same way I connected up both speakers and was quite pleased with the music coming out of them - they just keep getting better. It was getting late so I didn't have a whole lot of time to listen in stereo but the handful of pieces I played were very enjoyable. I can't wait to hear what the stands bring to the performance and Linnofil says they're done and I should have them soon!

So has anybody done much testing of different feet? I have some stick-on 3M bumpons that might work and also leftover LP12 rubber feet. But I also wonder if spikes would be better? Any feedback?

With any luck I might be able to get the subwoofer connected up, roughly positioned and playing this weekend. It should be interesting.

[lejonklou]

Thomas, have you removed the filters from both speakers? Have you also changed the internal wiring? How do you think the character and performance has changed with these modifications?

My plan was to change wiring and later remove the filter in one speaker at a time, to make sure it really gets better with each step.

Over the years, I've grown sceptic of the changes that I'm certain will be positive. So I need to double check.

[Music Lover]

So has anybody done much testing of different feet?

Just two so nothing really to report.
(best was the feet from my old Netgear ReadyNAS, with adhesive tape)

[ThomasOK]

Thomas, have you removed the filters from both speakers? Have you also changed the internal wiring? How do you think the character and performance has changed with these modifications?

My plan was to change wiring and later remove the filter in one speaker at a time, to make sure it really gets better with each step.

Over the years, I've grown sceptic of the changes that I'm certain will be positive. So I need to double check.

Yes, I have done both speakers and replaced the inner wiring with K400 using Deltron banana sockets. I did them one at a time so I could compare the external crossover mod with a stock speaker and I was quite happy with the improvement. This is all detailed in a post above that I put on here 7/27 - you might have missed it while you were on vacation. The internal K400 was as long as needed to reach the connectors and allow me to solder to the drivers without too much difficulty. I would estimate they are about two feet long or a little less. I only stripped the black from the very end of the cables to keep the twist as long as possible. I also kept the K400 together where possible in the hopes this would keep the cable mostly draped inside and away from the cabinet walls. It did have to be split a fair way back from the drivers to allow it to exit the two holes.

Musically I found that the resulting sound was more tuneful, had a bit better timing and allowed me to hear deeper into the mix - the playing of all instruments sounding like there were better musicians. It was not as big a difference as I would expect the stands to make from the reports here, but it was significant and worthwhile.

I did not change the internal wiring by itself as that might have required different length of cable and a lot of extra work. Also I soldered the bass driver directly to the metal straps that the tinsel leads are connected to. That and the fact that the tweeter connectors are held in plastic made me want to minimize the number of times I solder to them.

[matthias]

Fredrik,
did you get some results with modifying the tweeter protection circuit of the 3677?
Thanks

Matt

[lejonklou]

Fredrik,
did you get some results with modifying the tweeter protection circuit of the 3677?
Thanks

Matt

Yes, the Swedish group of 3677 owners collaborated in testing various resistors (including no resistor) instead of the protectors. The result was very interesting: The protectors seem to make the HF driver sound better! They can't be removed without the speaker performing worse.

--- This post and the previous was moved from the topic "Klångedang T1" ---