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Multi-Way Conventional loudspeakers with crossovers

SBA 741 vs. SBA 761 for Classical Music
SBA 741 vs. SBA 761 for Classical Music
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Old 13th September 2019, 02:51 PM   #71
pkitt is offline pkitt  United States
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I concur.
Paul

Quote:
Originally Posted by classicalfan View Post
But I would just express the idea in different terms. Specially, a speaker that sounds good with simple music may or may not sound good with more complex and demanding music.
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Old 14th October 2019, 02:50 PM   #72
asterduc is offline asterduc  Belgium
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Default 761 build

I came across this topic searching for 'Troels 761'.
For what it's worth;
Couple weeks ago I got a rental request for a speaker system to present Classical music on a private location from today 'till the end of the month.
The listening room will have 35 people listening to the music for 2 hours. Speakers to be placed close to a glass wall.
As I only have some OB speakers and full range satelites available at this time, I decided to build an easy and cost friendly floorstander for this purpose.
Instead of doing my own design, I went to the SBA 761 as the concept fitted in what I had in mind.
Finished the speakers on Saturday and they are running in as we speak.

My first impression is that this floorstander has balls! take into account that I'm used listening to OB, so the dynamics of the 761 are impressive to my ears.

There is lots of bass, not sure if I can get more slam and sub out of it after running in, doing some tuning with reflex pipe and dampening material.

Mids are great, I don't like midrange coming from small drivers, so the 16 does it well.

Treble was disappointing when I listened to the first tracks (before running in), there was a clear audible sibilance. I'll check in the next days if that goes better. Looking the measurements I notice an spl increase from 10K to 15Khz, I might suspect that this could be the source for the sibilance.

I copied Troel's design but made 2 separated enclosures, one for the 6+1" and one for the 7".
I also used a plastic reflex pipe in the back panel for the bass enclosure.
The monitor front panel is angled in my units and I decreased the tweeter resister accordingly to compensate for the off axes spl loss.

Installation will be done in the next hours, presentation tonight. I have good confidence that sound will be okay for the classical music.
I'll try to drop a line with my findings in the next days.

They will run on a Marantz 6006 or otherwise Lyngdorf with room perfect if there are acoustical problems (bass) with the room.

As for the attached SPL graph, this is an 'in room' measurement at 1 meter distance using ATB software, the strange behavior below 300 hz is room measurement error.

Some pictures on the construction work can be seen here SBA Satori mon&bas - Google Photos
Attached Images
File Type: jpg SBA 761 SPL.jpg (172.5 KB, 251 views)
File Type: jpg IMG_20191014_152738.jpg (215.8 KB, 257 views)
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Old 14th October 2019, 11:30 PM   #73
phillil is offline phillil  United Kingdom
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Hi Classicfan,

I just have a quick question.... why specifically are you wanting to try the DIY route?

It seems that you are after something quite specific, that you haven't been able to find in a commercial speaker. What makes you think that the SBAxxx will be to your tastes?

The reason I ask is because I also had a drive to persue the DIY route, but for me it was more out of curosity, a need for a second system and becoming totally disillusioned by a particular commercial brand.

I have been building subs for many years now, but have been put off by DIY speakers due to the art of xover design. Perfectly good drivers can be completely ruined by bad xovers, and that really worries me.

Equally, a good sounding speaker can be made to sound "better" (to certain listeners / in certain conditions) by tweaking the xovers (slopes, frequencies, padding, notching etc.) to suit ones particular tastes.

Whilst I don't think anyone can argue against my points above, in practice it can be very difficult to carry out these tweaks.

Personally I couldn't just take the risk paying a few hundred on some capcitors, only for them to become redundant because I want to tweak the design which requires new uF values. I would also be worried about how much to spend on the xover components.... they do effect sound, but by how much??

And on top of that, to make fairly simple changes to xover design can take quite a while to implement.

So I guess you can see where I am going with all this!!

So being a newbie to DIY, I decided (despite spending a few hundred hours playing with xsim and researching xover best practice and design) I just couldn't cope with the worry of it all, so decided to go down the active route.

I figured that if I started out with reasonable quality drivers, and a reasonably good DSP/amplifier, I am able to experiment with things such as levels, xover points, different slopes, time alignment etc. to see how each impact the sound. I can then work out what I prefer and yeilds the kind of sound I am after.

So that's exactly what I've done. I knew what characterstics I liked, and have had an awful lot of fun working out to acheive it. Some of the things I have learnt and prefer go completely against what I understood about so called best practice.

For example, trying to acheive a ruler flat response by notching baffle correction and other small peaks just made the overall sound worse to me. There seems to be a certain rawness about not using passive xovers (and too many digital filters) that I just prefer.

Also, I MUCH prefered the sound when crossing the 12" bass driver to a higher 400Hz (Troels uses 200 Hz in many similar designs), despite driving the 12" cone into breakup and the so called beaming effect. Crossing over the large cone made the presentation bigger, and I was able to feel guitar strings being plucked and the energy in brass.

I won't go on because appreciate this may be boring and will upset the purists, but there are a few more principles that I have learnt that I can implement in my final design, which may involve investing in a few more drivers.

So overall I have really enjoyed my active journey and really enjoy listening to my new speakers. For sheer excitement levels, I would say they are at least on par with my main system (B&W 800 with Classe monos). However I cannot comment on out-and-out quality becuase they are in different rooms with vastly different environments.

There are quite a few more things I need to try out, but all I need to do is load up different presets that have different crossover settings, then I can switch between them at the click of a button. So I can instantly hear the effect of delaying the tweeter, or switch between LR2 / LR4 for example.

I have learnt an awful lot about the theory of loudspeaker design and am very grateful to you all on these forums and the like of Troels. But I think it is equally important to learn by experimentation, and active really makes this easy
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Old 15th October 2019, 08:24 AM   #74
classicalfan is offline classicalfan  United States
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Phillil,

Thanks for your suggestion to go the active crossover route. And that, in fact, is one of the things I’m currently considering.

I already have a miniDSP 2x4 HD, UMIK-1 microphone, and REW software. So I have the tools needed to implement an active crossover. I’ll still need to buy a multichannel amp and there are several Emotiva products that look good for the purpose.

My real challenge now is how to handle a relatively small room. It’s only 11’x 12’x 8’.

Several posters pointed out earlier in this thread that there can be a lot of smear due to early reflections in a small room, which can ruin the sound quality. Particularly from a bare round dome tweeter. I hadn’t been seriously considering that factor before, but after their comments I am doing so now. There were multiple recommendations to use a wave guide with the tweeter to address this issue.

There were also strong suggestions to keep the midrange size to about 4” in order to get the type of transient response and sharp attack that I’m looking for in the sound.

I’d really like to find a kit by a well respected designer that has this combination of features. But I haven’t found one, yet.

So it may come down to exactly what you are proposing. Buy the drivers that I want and learn how to tweak the crossover in the miniDSP. Thanks for reinforcing that idea. I seem to be leaning more and more in that direction, particularly since I can’t find a kit that I like.

Last edited by classicalfan; 15th October 2019 at 08:30 AM.
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Old 15th October 2019, 12:27 PM   #75
phillil is offline phillil  United Kingdom
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It's an absolute pleasure. I spend a lot of time reading others advise and experience, so am only too happy to take the trouble of sharing mine.

Whilst I don't have the depth of knowledge and experience that others may have, I have become accustomed to so called "hi-end hifi" having spent the last 10 years living with B&W 800D2 and Classe electronics.

What resonated with me about your post was really the point you made about distortion. When people see my setup and ask for a demo, inevitable they want me to crank up the volume. However they generally want me to go past where I feel is at a comfortable level, and distortion starts to creep in. It's like siblance, only at a lower frequency, but it appears I'm the only one that can hear it.

So when I built my actives, I did consider a 4" mid, and it is something I will definitely consider in the near future. Instead I opted for 6.5" mid + 1" dome

For normal listening levels, the 6.5 + 1 is fine, but if I really (really) push it an edginess creeps in. I suspect either the tweet doesn't like going so low, or the mid so high, but the issue is suppressed somewhat by changing from LR2 to LR4.

The difference in sound (presentation) is surprisingly different and I need to do some more hours of listening to determine which I prefer.

It's good to hear you're at least considering active. Whilst there's no guarantee you'll get perfection, I can guarantee you'll have some fun!!

Good luck!
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Old 15th October 2019, 08:26 PM   #76
system7 is offline system7  United Kingdom
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I do think if you are serious for classical music, like this stunning Chopin by Daniel Barenboim which has a complex spectrum, and hence a tendency to distort when loud, nothing but a good three way will satisfy. Like the SEAS 3 way Classic by Troels Gravesen:
SEAS-3-Way-Classic

This is based on some pure mathematics by Steen Duelund:
Click the image to open in full size.

A two way is usually based on this, and you will see this overall curve in some of Troels' two way designs:
Click the image to open in full size.

3 ways go louder without distortion, so also handle complex loud peaks well too. 2 ways and 2.5 ways are just not so good at this, mainly because the drivers are having to perform in frequency areas where they have problems. And I could add that IMO, steeper LR4 filters have less distortion than shallower LR2 filters, albeit they lose something in liveliness. All is compromise in speakers... LOL
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Last edited by system7; 15th October 2019 at 08:53 PM.
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Old 15th October 2019, 08:48 PM   #77
phillil is offline phillil  United Kingdom
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Sorry forgot to add, my 1" + 6.5" sits on top of a sealed 12"
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Old 15th October 2019, 09:03 PM   #78
system7 is offline system7  United Kingdom
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It's certainly a good idea to relieve the 6.5" mid of bass duties as much as you can.

This is because a mid becomes more linear if not subject to excessive excursion.

So less distortion. I have heard some exceptional MTM styled Scanspeak 6.5" mids working with huge 15" bass reinforcement. They then crossed to RAAL ribbon tweeters around 2.5kHz on electronic LR4 crossovers in an acoustically treated room.

But that system cost about 500,000!

Me, I have a more modest budget...
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Old 16th October 2019, 05:01 AM   #79
classicalfan is offline classicalfan  United States
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Quote:
Originally Posted by system7 View Post
It's certainly a good idea to relieve the 6.5" mid of bass duties as much as you can.

This is because a mid becomes more linear if not subject to excessive excursion.

So less distortion. I have heard some exceptional MTM styled Scanspeak 6.5" mids working with huge 15" bass reinforcement. They then crossed to RAAL ribbon tweeters around 2.5kHz on electronic LR4 crossovers in an acoustically treated room.

But that system cost about 500,000!

Me, I have a more modest budget...
This would seem to indicate that MTM is the preferred configuration over others, since the system cited is obviously a no-cost-limit situation. For that amount of money they could have done anything they wanted, yet chose to use MTM.

So, if that's the case maybe we should make MTM one of our first options in choosing new speaker designs. It's certainly something that I have been considering lately.
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Old 16th October 2019, 07:35 PM   #80
system7 is offline system7  United Kingdom
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MTM has a lot going for it, IMO.

The midbasses work together to provide the same SPL at the on-axis listening position whilst throwing half the power into the room, which is the bit that annoys the neighbours upstairs and downstairs.

The PA people have taken it further with things like vertical 4X 12" bass cabs common with concert venues and loud rock bands.

This speaker was much liked in the 1970's, the Wharfedale E70 owned by my flatmate. A little delving reveals the paper mids were wired in series, which is my preferred option in a common enclosure. And we should mention that a dedicated mid is a slightly different animal from a midbass. Highly efficient, it did something entirely well:

Click the image to open in full size.

Great midrange voices delivered with clarity. 300Hz to 3kHz was considered by the telephone companies of the day as essential to good voice clarity and listening.

This is a much more contemporary LR4 Gryphon loudspeaker:

Click the image to open in full size.

SEAS CA15RLY midbasses and a Mundorf ribbon tweeter. It's nearer an MTTM than anything else. Probably not the last word in deep bass, but about as good as it gets in a small room. And very well matched on vertical dispersion.

Mr. Troels Gravesen has probably built more speakers than most of us have had hot dinners: DIY-Loudspeakers

I like Visaton Boxsim to try out ideas. And a good idea is what we all need really. Thus I would think that doubling the mids in Troels' 3 way classic, to get nearer the E70 is a much more interesting idea than swapping out one competent driver for another: SEAS-3-Way-Classic
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Last edited by system7; 16th October 2019 at 07:52 PM.
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