JBL 4645C

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Re: JBL 4645C

Post by Spannko » 2017-01-27 17:04

Thanks ML. I notice that you're using sound absorbers behind the speakers. What sort of difference do they make? I'm planning on trying out some room treatments, but there's so much marketing fluff, it's difficult to sort out the wheat from the chaff!

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Re: JBL 4645C

Post by Music Lover » 2017-01-27 21:14

Spannko wrote:Thanks ML. I notice that you're using sound absorbers behind the speakers. What sort of difference do they make?
It's from the same person which supplied the sub filter.
They enhance the musicality (and sound)
Be careful, most acoustic panels are NOT good. The good ones are designed to have a good mix of absorbing/diffusing the midrange and treble.

But it's just serving as an additional treatment in the room.
The main treatment is "normal stuff" as thats best that way. You find the bookshelf on the right wall, diffusing/damping the first reflex. I have a similar bookshelf at the left back corner. And a big sofa, lots of Persian carpets and pillows.
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Re: JBL 4645C

Post by Spannko » 2017-01-28 01:11

Music Lover wrote:
Spannko wrote:Thanks ML. I notice that you're using sound absorbers behind the speakers. What sort of difference do they make?
It's from the same person which supplied the sub filter.
They enhance the musicality (and sound)
Be careful, most acoustic panels are NOT good. The good ones are designed to have a good mix of absorbing/diffusing the midrange and treble.

But it's just serving as an additional treatment in the room.
The main treatment is "normal stuff" as thats best that way. You find the bookshelf on the right wall, diffusing/damping the first reflex. I have a similar bookshelf at the left back corner. And a big sofa, lots of Persian carpets and pillows.
That sounds really interesting. Who makes them?

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Re: JBL 4645C

Post by Spannko » 2017-02-08 23:30

I've just read that linn are releasing Exakt.Design next month. It's the software which enables you to design Exakt crossovers. And best of all - it's free!

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Re: JBL 4645C

Post by Music Lover » 2017-02-08 23:56

Spannko wrote:I've just read that linn are releasing Exakt.Design next month. It's the software which enables you to design Exakt crossovers. And best of all - it's free!
So I can configure a filter with output to:
- 3677 horn?
- 3677 bass driver?
- 4645c sub?

With ALL settings according to my taste?
They finally have listen and understood that this is the only reasonable way forward!
Still...I'm a bit sceptical until I have tested it myself.
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Re: JBL 4645C

Post by Music Lover » 2017-02-10 16:43

Spannko wrote: That sounds really interesting. Who makes them?
Sorry, missed this Q.
It's Ingvar Öhman's design but a subcontractor to him makes them. Ingvar is the designer of the sub filter.
Originally he is an acoustic technician. He has no formal education, but I've heard a few hifi and home theatre rooms he designed. He knows what he is doing. NOTE, these rooms are specially designed for HIS speakers = not applicable on other speakers. (Linn, JBL etc)
But the "Ino Aco" panels are good in any application.

They are 1,2*1m and are only sold in pairs at around 150€/pair.
If you buy 4 or more they can be sent, even internationally.
They are effective from 300Hz and up.
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Re: JBL 4645C

Post by Spannko » 2017-02-11 11:02

Thanks ML.

I've heard the designers speakers with Rega's most expensive CD player and integrated amp and thought they were excellent. He certainly knows what he's doing!

I'll see if I can get a couple of his panels and try them out.

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Re: JBL 4645C

Post by sunbeamgls » 2017-02-12 13:36

Music Lover wrote:
Spannko wrote:I've just read that linn are releasing Exakt.Design next month. It's the software which enables you to design Exakt crossovers. And best of all - it's free!
So I can configure a filter with output to:
- 3677 horn?
- 3677 bass driver?
- 4645c sub?

With ALL settings according to my taste?
They finally have listen and understood that this is the only reasonable way forward!
Still...I'm a bit sceptical until I have tested it myself.
Yes. And different for each speaker too - so you can have a subtly different output for the left speaker than the right speaker - which could be useful given the JBL's fairly generous build tolerances (in the cabinet at least, perhaps elsewhere). You design your own crossover points and slopes too. If you have 2x subs you could include them in the speaker design. However, for 1x sub you need a stand alone filter design. It will be interesting to find out what a phase linear pair of 3677s sound like. The only reservation I would have at the moment is that I'm not sure that the tool specifically deals with horn designs - perhaps it is just a matter of guidance, perhaps it needs to interpret the electrical measurements differently and that would be a software change? If you go to Scalford you can ask them :)

You need to be able to measure the speakers electrically and you do need an Exaktbox to interpret your free to design filters of course, for the moment. You could use 2x Exaktbox 6 for the stereo pair (including stereo subs) or 1x Exaktbox 6 for the stereo pair and an Exaktbox Sub for a mono sub. If you have stereo subs you'll get better results with Exaktbox 10. And your JBL warranty will be null and void.

Of course, some think Exakt is the work of the devil...
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Re: JBL 4645C

Post by Music Lover » 2017-02-12 15:52

Thanks för explaining.
But these sentences don't match, or did I misunderstand?
sunbeamgls wrote: If you have 2x subs you could include them in the speaker design. However, for 1x sub you need a stand alone filter design.
sunbeamgls wrote:
You could use 2x Exaktbox 6 for the stereo pair (including stereo subs) or 1x Exaktbox 6 for the stereo pair and an Exaktbox Sub for a mono sub.
sunbeamgls wrote:
It will be interesting to find out what a phase linear pair of 3677s sound like.
I know Linn make a big deal of this but according to me, that is impossible as the speaker elements are not phase linear over the frequency range. Then you move in the room and then the phase relationship between the 2 elements are changed.
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Re: JBL 4645C

Post by sunbeamgls » 2017-02-12 19:01

An Exaktbox 6 has 2x 3 channels when used in stereo. So, if you considered a 3677 horn tweeter, 3677 mid-bass and a 4645 sub driver as effectively a 3-way design then you can use this one Exaktbox to drive 2x 3 way speakers. You would have to define a fixed physical relationship between the 3677 and 4645 to treat it as a 3 way design. It works in stereo. If you had only one sub then then you no longer have 2x 3-way speakers. So then you have to have 2x 2way in the Exaktbox 6 and a stand alone 1x Exaktbox Sub to feed the mono subwoofer.

And yes, Exakt produces a near-linear phase speaker. At crossover points and within the drivers (but with limitations around things like temperature changes). That's the biggy - they have developed a way of delivering linear phase crossovers and the ability to deliver driver phase non-linearity correction in real time. Near phase linearity is across the frequency range coming out of each speaker cabinet. Its not trying to deal with the room.
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Re: JBL 4645C

Post by Music Lover » 2017-03-15 10:02

Short update.
Had a few mails back/forth with Linn regarding Exakt.Design.
Linn made a demo during a hifi-show in UK, and got an invitation, so I asked for a live-demo (Webinar) for us outside UK but "it couldn't be done".
So I just wait...

But I'm seriously stunned by the performance of my amps/speakers, every time a got a chance listening.
Over time, it's better and better but now extremely little. I should say it's burned in by now.
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Re: JBL 4645C

Post by sunbeamgls » 2017-03-16 14:29

^ apparently www.thewam.tv will be recording the demo and this should be posted on 20 March.
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Re: JBL 4645C

Post by Music Lover » 2017-05-26 15:08

Music Lover wrote: But I'm seriously stunned by the performance of my amps/speakers, every time a got a chance listening.
Over time, it's better and better but now extremely little. I should say it's burned in by now.
Over two months later the performance has been stable during this period.

I have to say...again, it's stunningly good!

And then you believed it wasn't possible to make it better, Linnofil made a short pitstop where we changed the PreProd 4645C-Ofil stand for the production design.
Incredible, we both just looked at each-other with a silly grin. A GOOD step better.

I'm super happy and anyone the consider the 3677's, MUST invest in 4645C/Ofil stand.
It lift the performance a LOT from the 3677/Ofil stands. And in addition bring more slam and that unique live feeling that only a true full range system can.

As they say...Highly Recommended.
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Re: JBL 4645C

Post by cortina » 2017-05-27 12:00

Those of you with 3677s and 4645C:
- What room dimensions and wall material have you got?
- What's the distance between the speakers and where did you place the sub(s)?

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Re: JBL 4645C

Post by Linnofil » 2017-05-31 19:14

Music Lover wrote:And when you believed it wasn't possible to make it better, Linnofil made a short pitstop where we changed the PreProd 4645C-Ofil stand for the production design.
Incredible, we both just looked at each-other with a silly grin. A GOOD step better.

I'm super happy and anyone that considers the 3677's, MUST invest in 4645C/Ofil stand.
It lift the performance a LOT from the 3677/Ofil stands. And in addition bring more slam and that unique live feeling that only a true full range system can.

As they say...Highly Recommended.
Thank you Music Lover! That was a great moment, the first few seconds after a new upgrade that works is such a great feeling. First you get that wow feeling and then the realization that this difference will be there on all songs from now on. Is that what you call true happiness? :)

I'm really satisfied with the performance of the sub stand after having done all the development and testing. As Music Lover said, they are now ready, in production status. I actually have these sub stands in stock now, order via pm if you want one. Price is 4500 SEK + shipping.

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Re: JBL 4645C

Post by Music Lover » 2017-10-19 16:59

ThomasOK wrote:I just received word that my Marchand crossover shipped. I look forward to seeing if it will be musically superior to the Dahlquist. I ended up getting a different model than the one I had originally intended to. This model doesn't allow you to change frequencies on the fly but is actually much more flexible and Phil Marchand said the magic words: "This one is more musical than the other."

For those interested the one I ordered is the XM44. A basic version of this that would be sufficient for a sub crossover would run about $800 vs. the $850 for the XM66 I had been looking at. However, instead of ordering the basic 1 way model I went ahead and ordered a 3 way version (you can get up to four way). I also ordered the better stepped attenuators that allow 1/2dB adjustments of level instead of 1dB increments. With this model it would be possible to go full active with the JBLs if I wanted to litter my room with Tundra Monos! It did, however, boost the price to $1600. Internally it is interesting in that it uses plug in cards that are quite inexpensive and there are three card slots for each channel and division. So you could combine the rolloff card with the subsonic filter card and even an eq card if desired. It also has a summing switch for the low frequency section for use with a single sub.

As ordered it will come set for 80Hz at 24dB per octave rolloff of the sub and with an 18db per octave 22Hz subsonic filter. These are the settings Fredrik and Jajo found to be the best which theoretically gives it an advantage over the Dahlquist which has no subsonic filter and an 18dB slope to the sub. It will be very interesting to see how it fares. If I find it to be a better option than the Dahlquist I will also be able to be a dealer for his products.
So with the predefined 18db@22Hz and 24dB@80Hz@24dB, the only setting is then amplitude right?

1. Did you compared it with Dahlquist? Thoughts...
2. How did the Marchand setting at the RMAF 2017 differ, compared with home?
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Re: JBL 4645C

Post by ThomasOK » 2017-10-19 17:43

Yes, only the amplitude setting can be easily changed on this crossover. However, the frequency and slope, as well as the subsonic filter, are set by plug-in cards. There are, in fact, three card slots in each section so if someone wanted to try a +7dB eq at 22Hz (that JBL suggests if you want flat response to 22Hz) it would be easy to do. As the cards are quite inexpensive, generally running $10 to $15 each, it is quite simple to try different settings if you want.

I have compared it with the Dahlquist and find the system more musical with the Marchand. I found I needed to do this comparison with the whole system running to really appreciate what was going on. When I tried the comparisons with just the subwoofer running the change from the 24dB per octave Marchand and the compound 6/12/18dB per octave rolloff on the Dhalquist made too much difference in the sound.

I believe the the level was set 1/2dB different at the show than at home. However, Fredrik showed his subwoofer setup technique, originated at Linn, and we spent a fair bit of time tuning the sub placement until it really rocked before connecting the rest of the system. In my system at home it was in a significantly different position, especially in relation to the side wall, and faced 90 degrees to the main speakers. It will still have to remain 90 degrees to the mains due to space limitations in my room but I will reposition it using what I learned at RMAF to optimize it. This may cause a slightly less optimum placement of the mains (a little closer together) because of where the stands end up but I believe optimizing the sub will make it worth it.

Also at the show was the first time I had a chance to properly torque the Marchand which has a lot of fasteners. Fredrik and I tuned it together and the improvements were as expected - a more musical bass perfromance. There are several more fasteners I didn't have time to get to as they needed partial disassembly that I will further optimize before putting the system back together.
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Re: JBL 4645C

Post by ThomasOK » 2017-10-19 18:21

Fredrik mentioned some interest in the Marchand XM44 after the reports at RMAF. It seems like here would be a good place to share some more information about it. I find the Marchand XM44 to be a pretty musical piece at a modest price. He also makes other crossovers that could work but the pricing is about the same. When I talked to him about them he recommended this model "because it sounds better". Good enough.

There aren't a lot of general purpose electronic crossovers on the market and fewer yet that can be customized to work well for the 4645c requirements. But the Marchand does fit the bill. The crossover you see in the RMAF photos does look a little busy but that is because I ordered a 3-way version in case I wanted to go full active on the 3677s at some point, a simple task in terms of wiring since my passive crossovers are external. I also was taking a chance buying this without hearing it so I felt a 3-way would be easier to resell. As mine is configured it would sell for $1600 but that would include a full set of cards for a 3-way crossover. Also there are those black knobs with light grey fronts which I may do something about.

However, it is available as a one way unit for just crossing over a sub (as well as 2, 3 and 4-way). A basic one way unit would be $800 including cards. However, I also recommend the upgrade to 1/2dB stepped attenuators in place of the 1dB standard parts as I feel 1/2dB is significant. This adds $300 to any configuration bringing it up to $1100. Standard config is 24dB per octave Linkwitz-Riley slope at any frequency. But you can specify any crossover frequency and any rolloff from 6db to 48dB per octave in 6dB increments, and you can have the subsonic filter which he customized for me to the 22Hz frequency Jacob and Fredrik found best. The unit comes with a summing switch standard for use with single subwoofers (imagine TWO 4645cs!). It also comes standard with input voltages of 117 or 230 volts set by a back panel switch. I am a dealer for Marchand so I can get units for anyone interested. I also asked him if it was OK to fit a blue LED and he said he had some there he could install at build time if requested. Other options are Balanced outputs/inputs, baffle step compensation, notch/boost filters, delay sections and bass boost filter (Linkwitz transform). Balanced connections are additional cost, filter boards are only $10 to $15 each.

As mentioned previously, and as expected, it does sound better when properly torqued and there are quite a few fasteners as he is fond of screw terminals for both signal and power supply wiring. There are also gains to be had from some slight rerouting of internal wiring as Fredrik and I discovered at the show. I think that about covers it but I'd be glad to answer any other questions.
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Re: JBL 4645C

Post by sunbeamgls » 2017-10-19 19:23

It would be interesting to read about going active with 3677s Thomas. Recent experience with Naim and Kudos suggests it brings out a lot of music lost in passive crossovers. The Kudos speakers seemed to gain more, musically, than Linn speakers, although it might be that Naim make a better active crossover than Linn.
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Re: JBL 4645C

Post by Music Lover » 2017-10-19 20:40

sunbeamgls wrote:It would be interesting to read about going active with 3677s Thomas. Recent experience with Naim and Kudos suggests it brings out a lot of music lost in passive crossovers. The Kudos speakers seemed to gain more, musically, than Linn speakers, although it might be that Naim make a better active crossover than Linn.
The 3766 X-over is very good as Fredrik and Christian tried improving it but failed.
So not so sure an external active filter going to be an improvement actually.

But surely, being able to play louder is always welcomed :)
On the other hand, in my setup it's the Tundra Mono feeding the sub that is the limitation. It's always that amp that start clipping first.
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Re: JBL 4645C

Post by sunbeamgls » 2017-10-19 21:02

Music Lover wrote:
sunbeamgls wrote:It would be interesting to read about going active with 3677s Thomas. Recent experience with Naim and Kudos suggests it brings out a lot of music lost in passive crossovers. The Kudos speakers seemed to gain more, musically, than Linn speakers, although it might be that Naim make a better active crossover than Linn.
The 3766 X-over is very good as Fredrik and Christian tried improving it but failed.
So not so sure an external active filter going to be an improvement actually.

But surely, being able to play louder is always welcomed :)
On the other hand, in my setup it's the Tundra Mono feeding the sub that is the limitation. It's always that amp that start clipping first.
Its a fair point ML. It may be a very good passive crossover. Trying to improve it just proves its already a very good passive crossover, it doesn't really tell us much about how it would compare to an active crossover (or at least not a very good active crossover as I guess there's just as much opportunity to mess that up as thereis the opportunity to mess up a passive crossover).
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Re: JBL 4645C

Post by Music Lover » 2017-10-19 22:09

ThomasOK wrote: However, it is available as a one way unit for just crossing over a sub (as well as 2, 3 and 4-way). A basic one way unit would be $800 including cards. However, I also recommend the upgrade to 1/2dB stepped attenuators in place of the 1dB standard parts as I feel 1/2dB is significant. This adds $300 to any configuration bringing it up to $1100. Standard config is 24dB per octave Linkwitz-Riley slope at any frequency. But you can specify any crossover frequency and any rolloff from 6db to 48dB per octave in 6dB increments, and you can have the subsonic filter which he customized for me to the 22Hz frequency Jacob and Fredrik found best.
Thanks for the detailed feedback, appreciated!

So a one-channel XM44 is $1100 with exactly the correct rollon/rolloff freq and slope.
Is the box the same size as the 5-channel unit you now use? A bit on the large side to fit on my Yggdrasil shelf...
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Re: JBL 4645C

Post by ThomasOK » 2017-10-20 18:20

Yes, it is the same size box. The only crossover he makes that is available in a compact package is a passive filter.
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Re: JBL 4645C

Post by COMSTEDT » 2017-10-22 00:35

Since you bought a 3way cover. Then technically you could use it for up to 2 subwoofers and still have one channel left?

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Re: JBL 4645C

Post by ThomasOK » 2017-10-22 16:07

COMSTEDT wrote:Since you bought a 3way cover. Then technically you could use it for up to 2 subwoofers and still have one channel left?
Actually it is a 3 way stereo crossover so 6 channels total and 4 still available. It could be used with two subwoofers as is just by connecting them and turning the summing switch off. The one way version would also support one or two subs.
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