JBL 3677

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ThomasOK
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Re: JBL 3677

Post by ThomasOK »

matthias wrote:
ThomasOK wrote:I've been told that the C211 is not discontinued........
Thomas, you mean the 3677?
Sadly I see no sign that it is not discontinued.
So the 3677 is no longer listed in the JBL 3000 series:

http://www.jblpro.com/www/products/cine ... ZReQNGbGhA

But I am sure they will get cult status like the Briks.

Matt
Yep, that's what I meant, now corrected. Apparently my mind was still on vacation. I see what you mean from the link. That would be really unfortunate as the C211 is certainly not a suitable replacement for us, not only for all the reasons already stated about size and configuration, but also because it is unlikely to be as musical. I still haven't heard back from my rep but I'll let you all know what the word is when I do.
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Re: JBL 3677

Post by Music Lover »

Why assuming it's not as musical? I suggest a fast test.
And put it up-side-down please :)
It's all about musical understanding!
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Re: JBL 3677

Post by matthias »

Agree,
someone should compare the C211s to the 3677s.

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Re: JBL 3677

Post by ThomasOK »

This would appear to make it pretty much official:

http://www.jblpro.com/www/products/vint ... ZW10HeGPLg

This is what comes up when you go to the JBL Vintage web page where there are links for information on discontinued products. The 3677 is listed on that page and this is where it takes you. I'm still waiting to hear back on the ones I have back-ordered.

By the way, I didn't assume it is not as musical, I said I thought it was unlikely. I still do think it is unlikely. Why?
1) According to others on the forum whose ears I trust, mainly jajo, none of the bigger 3000 series nor the 4000 series are as good as the 3677. So it may be sheer luck they got this one right.
2) The person most likely to have been the head designer on the project, Greg Timbers, was summarily dismissed by Harman about two years ago. So it will likely be a different group who designed the C211.
3) The C211 uses different drivers, quite a different cabinet, different layout and a different crossover and was built to be less expensive. Somebody would have to be really good to get all these to work as well as the 3677 does. Does lightning strike twice in the same place?

Certainly it would be interesting to see what somebody finds out in a comparison of the two. Turning it over might work but note it can't work that way with Ofil stands as the connectors would then be at the bottom. Note also that the ports would then be at the bottom of the enclosure instead of quite a bit higher up so the optimum distance to the floor will likely be different. It is also possible that the dispersion is optimized for the normal placement so the driver integration might be less good upside down. But I'd certainly like to hear what somebody here finds out from such a comparison.

Personally, I'm going to check again on the pair I have back-ordered for a customer and find out if there will be any more available from the last production run.
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Re: JBL 3677

Post by Masi »

Thanks for your interesting thoughts, ThomasOK.
I need some advice: I have the chance to get a pair of 3677's for around 880 Dollars per piece. Price in Europe are slightly higher than in the US-Market.
Should I go for the 3677 or maybe wait some time till there are some reviews of the new C211. But I think there is no much chance, that the new C211 can beat the old 3677. So maybe I should take the chance bevore they are sold out?!
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Re: JBL 3677

Post by ThomasOK »

Actually the price over here was $883 each so it sounds like it is about the same. If you found a place there that still has them you are lucky as nobody in the US stocks them since Harman direct ships to the customers here for no charge. As mentioned, Harman themselves are out and have been back ordered for months. I just called my rep and he told me he talked to Harman yesterday and they indicated that they currently show my pair coming off back-order tomorrow. As this is the fifth or sixth date I have been given I'm not holding my breath, however it is the closest date I have been given so far so maybe they really will ship. I asked him to check and see if Harman will have any stock available after filling the back orders so that I can try to snag a couple pairs myself to fill possible future orders. He said he would but that they have quite a backlog to fill so the manufacturing run may be sold out.

It is hard to say how long it will be before we see any reviews on the C211 and even longer before they come from anybody with ears I would trust (such as several on here). By that time the 3677 will likely only be available on the used market. I know that the only way I would get to hear a pair under any worthwhile condition is if I buy a set, which is not on the current agenda. I think you can tell which direction I would tend to go on this.
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Re: JBL 3677

Post by Masi »

After I had read a lot of stuff over the 3677, I think there must something be that makes this speaker so musical - I wont call it "magic". I will go for the 3677. Had a call with the dealer. They are sold out from the european stock. So the speaker must be shipped from the US. And it goes by ship. So it needs at least 6 weeks.
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Re: JBL 3677

Post by Masi »

there were a few recordings of 3677 playing music. I checked the dropbox-link. It's not working anymore. Has someone new videomaterial or a new link? Thanks
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Re: JBL 3677

Post by matthias »

Masi wrote:there were a few recordings of 3677 playing music. I checked the dropbox-link. It's not working anymore. Has someone new videomaterial or a new link? Thanks
You can google jbl3677 and you get at Videos CLIP1, CLIP2. CLIP3.

Even if you do not like the music, it sounds pretty good.

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Re: JBL 3677

Post by Masi »

Best clip I found was this: https://www.youtube.com/watch?v=CiyT4v_N5aI

Very good sound recording.
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Re: JBL 3677

Post by Masi »

Someone any news?

Looking forward DHL is delivering my parcel :)
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Re: JBL 3677

Post by ThomasOK »

While my rep confirmed that JBL were discontinuing the 3677s a couple months ago he still had some in stock and another shipment expected. So another of our forum members contacted me to take the plunge. He decided to have me do the external crossover mod and had a pair of nice wood boxes sent to me. Just today I finished the internal rewiring and torquing of the drivers. The crossover boxes were completed over the last couple weeks. Here is a link to some photos of the progress.

https://www.dropbox.com/sc/t7jtjhmagkoz ... hpS6REovma

He already has a set of Ofil stands and a full set of Monos to drive them. I expect he is going to be a very happy camper!
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Re: JBL 3677

Post by beck »

Very nice work Thomas.
Playing cd’s…………
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Re: JBL 3677

Post by matthias »

beck wrote:Very nice work Thomas.
+1
Thomas, what are your torque settings for both drivers?
Thanks

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Re: JBL 3677

Post by ThomasOK »

Thanks guys. His crossovers are prettier than mine. You get good at these things after a while. ;-)

Bass driver .4Nm + 5 notches. Horn to cabinet .4 - 7 notches, screws on back of tweeter magnet 1.2 + 2 notches. Tweeter magnet assembly threads onto horn. I don't have a measured torque there but find it most tuneful when threaded on until it is good and snug but not tight - pretty much just a hair after it grips.
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Re: JBL 3677

Post by sunbeamgls »

ThomasOK wrote:
Which brings me to the reason I started this post. Despite the size of the woofer in the 3677 it is not ever going down to 20Hz effectively if my understanding is correct. The size of a woofer is only one part of the equation as to how low it will go and is important as it governs how much air it can move. But as important is how low the driver is designed to go and the answer for the 2035HPL driver in the 3677 is not very low. That driver's free air resonance is in the neighborhood of 45Hz to 48Hz depending on which specs you read. This means that its response falls like a stone below that point. By port loading it as the 3677 design does you can use the resonance of the ports to extend that a bit. I believe the ports in the 3677 are tuned to 40Hz so around there or a touch lower is about as low as they are going to effectively go. While JBL doesn't provide frequency graphs on the 3677 they do on the 4638 which uses two of these drivers with similar porting. Its low end frequency is claimed as -3dB at 45Hz and -10dB art 30Hz. In the frequency response graphs for it you can see that this is pretty accurate with it being down about 18dB at 20Hz, 20dB at 30Hz, 3dB down pretty close to 45Hz (the graph isn't very high resolution so it could be 46 or 47Hz) and about 6dB down right near 40Hz. Normally 6dB down is about as low as is considered usable as it is one quarter power. There might be a little lift from the close wall placement but I don't expect it would help this very much. Considering the free air resonance a larger cabinet will not effectively allow it to go lower - it it just how the driver is designed.
Hi ThomasOK. Can you advise on where the port resonance data of 40Hz came from please? I can't find that data on line and your wording here suggests that you're not 100% sure. See my post below for why I ask.

Thanks
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Re: JBL 3677

Post by sunbeamgls »

Is anyone here willing to collaborate on getting the 3677 added to SPACE please?

All that is needed are some simple but accurate physical measurements plus the port resonance frequency.

The port resonance will either have to come from a specification (perhaps someone has a contact at JBL to get this info?) or if an owner has the ability to take a impedance by frequency sweep it can be ascertained from the measurement graph.

Normally this will be chargeable in the future but just building a few examples up first at no cost.
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Re: JBL 3677

Post by ThomasOK »

sunbeamgls wrote:
ThomasOK wrote:
Which brings me to the reason I started this post. Despite the size of the woofer in the 3677 it is not ever going down to 20Hz effectively if my understanding is correct. The size of a woofer is only one part of the equation as to how low it will go and is important as it governs how much air it can move. But as important is how low the driver is designed to go and the answer for the 2035HPL driver in the 3677 is not very low. That driver's free air resonance is in the neighborhood of 45Hz to 48Hz depending on which specs you read. This means that its response falls like a stone below that point. By port loading it as the 3677 design does you can use the resonance of the ports to extend that a bit. I believe the ports in the 3677 are tuned to 40Hz so around there or a touch lower is about as low as they are going to effectively go. While JBL doesn't provide frequency graphs on the 3677 they do on the 4638 which uses two of these drivers with similar porting. Its low end frequency is claimed as -3dB at 45Hz and -10dB art 30Hz. In the frequency response graphs for it you can see that this is pretty accurate with it being down about 18dB at 20Hz, 20dB at 30Hz, 3dB down pretty close to 45Hz (the graph isn't very high resolution so it could be 46 or 47Hz) and about 6dB down right near 40Hz. Normally 6dB down is about as low as is considered usable as it is one quarter power. There might be a little lift from the close wall placement but I don't expect it would help this very much. Considering the free air resonance a larger cabinet will not effectively allow it to go lower - it it just how the driver is designed.
Hi ThomasOK. Can you advise on where the port resonance data of 40Hz came from please? I can't find that data on line and your wording here suggests that you're not 100% sure. See my post below for why I ask.

Thanks
You had to dig pretty far back to find the post you quoted. I note that you didn't include in the quote the first sentence of the post but I will quote it here:

"Let me preface this by saying that I really know next to nothing about loudspeaker design."

That said the 40Hz port tuning was a guess based on the claimed 3dB down point or 45Hz and the fact that the port is normally tuned a little bit below where the driver rolls off to extend the bass. Additional research shows that I am very likely correct. First, I found a JBL spec sheet for the 4638 subwoofer cabinet that uses two of the same drivers as the 3677 and it shows a port tuning frequency of 40Hz. Second I found the specs on the driver that shows an Fs of 48Hz (although I have seen from 43Hz to 51.9Hz also quoted - it can vary slightly from one unit to the next). Anyway assuming 48Hz and using the formula I found on another website for port tuning of multiplying the Fs by .8116 comes up with an optimum port tuning of 38.96Hz. So I suspect it is indeed pretty much 40Hz tuning on the 3677 ports.
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Re: JBL 3677

Post by sunbeamgls »

Thanks ThomasOK.

As ever I was just to trying to understand. I asked the question because you had, quite rightly, caveated the estimated value and you articulate your thinking very well in the above post. Thanks for the clarity.

Im just trying to establish the information and an accurate value. Your thinking seems sound but, as you've said, its an estimate. For SPACE the value needs to be accurate so I'm hoping, as a community, an accurate value can be established.

From a Google search your post seems to be the only result that even mentions port resonance.

Would you have a contact at JBL with whom you would be prepared to raise the question please?
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Re: JBL 3677

Post by JH. »

Hi everyone. I just got a pair. In future I want to look into the custom stands. (Is it a member here?)

I was looking at PDF for technical stuff inside. It says impedance + aluminum wire. So I take it these are wired with aluminum? Has anyone replaced theirs with copper yet?

Has anyone calculated the Q of the box?

I suspect some capacitors are electrolytic. I’ll probably switch to film at some point, but realize they may be external, and in large boxes relative since it’ll take a good amount of film caps to equal near the 100uf total per channel.
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Re: JBL 3677

Post by JH. »

Perhaps I missed the boat here...

Speaker sound kind of amazing, but looking forward to speaker wire replacement as it does it appear they're aluminum. The crossover... I don't desire any changes except swapping to film caps. But my favorites that are very natural and -140db noise, only come in up to 4.7uf (ugh).

Still curious about the stands?
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Re: JBL 3677

Post by lejonklou »

Hello JH and welcome to the forum!

The internal wiring is not aluminum, but the voice coil of the bass unit is. I don't think you'd want to change that, but replacing the internal wiring with old Linn K400 is a clear improvement, as is removing the filters from the enclosure and putting them in external boxes (which requires some more work).

I don't recall any of the capacitors being electrolytic and would strongly advise against trying to improve them. We collaborated on this and tried a lot of things, but every change was for the worse - including replacing the light bulbs to the tweeter with resistors. The filters are amazingly spot on with every value.

The stands made by Linnofil (member on this forum, but I haven't seen him for a while) are a very worthwhile upgrade!
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Re: JBL 3677

Post by JH. »

Hi, thank you for the welcome.

The capacitors are 100% for sure electrolytic. Their size (physical) alone makes that true (although one or two small ones may be film, I didn't look super close). I have zero plans to change their values or remove lamps or anything. I just know that film caps prove to be better in every respect. When my crossover goes external it will be a good time to do the capacitor change. I'll get capacitors that'll run in parallel, to equal the schematic's values. I may also put in mills resistors as sandcast are pretty cheap.

What I want from improvements is just a slightly less aggressive sound that isn't as grey in tonal color. But I suspect new wiring may help bass a little. I don't have access to the K400 easily, as it's out of production. But I'll be using something very nice.

I'm going to save all the parts I change, just in case I don't like the results.
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Re: JBL 3677

Post by lejonklou »

Good luck!

Please remove those four screws that hold the speaker input cavity and have a look at the filter that sits on the other side. Then tell me which capacitor you think is electrolytic.

How do you evaluate the changes you're about to attempt? I have no idea about your experience with modifications, but in general I would say that any change of a capacitor or resistor to a supposedly "better" type (I write that within quotes because there is really no better or worse, only more or less suitable to the task) will tilt the sound of your speakers towards a more aggressive sound. But more importantly it will change the musical character and that must be judges with a musical evaluation process.

None of the changes we made, and they were many, resulted in a more musical 3677. I was rather surprised by this, as my first thought they'd be easy to improve upon.
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Re: JBL 3677

Post by JH. »

I'm familiar with the Tune Method. I also judge on musicality you could say. I'm not looking for "hifi" changes, but rather cohesive improvements that don't stand out awkwardly. I play some familiar non-audiophile LP's (hate MoFi), and give it some time. If I listen less than I use to, it was a bad change. If I want to listen more, it's a good change.

Perhaps I'm not the most experienced modifier but because I understand the electronics I know when possible mistakes are being made, as opposed to differences in character (I see horrible screw up mod all day online). That's why I won't change any values what-so-ever. IMO if a modification makes the sound more aggressive than something up the chain is likely showing it's true nature, or you've chosen poorly. I've seen both many times. For example I don't like metalized capacitors at all, won't use them. But I recognize in beginner systems they tend to add detail and stuff people seek. Were I to put them in the sound might become aggressive. I know what a lot of things sound like.

Here's a photo. C3, C5, C6 are all electrolytic (irrefutably). What's smart by JBL is that they're less critical in that C3 is bypassed by C2 which is film, C5 is a notch filter not series, and C6 is bypass part of 3rd order crossover so it's meant to pass high frequencies that don't go to woofer. The crossover is smart, but I still wouldn't call these film caps my favorite. They're cheap, but the good thing is they tend to be on a friendlier, if not slightly more boring sound to most. Well the JBL 3677 isn't boring so they are a better fit than with most. Still I prefer 940C caps to everything, lowest distortion, most natural sound.

Image

The real challenge is if replacing electrolytics with film you have to match their ESR, often with a resistor. It's all work for the future at this time.
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