SB29SDAC-C000-4 + 2xSB 17NBAC35-8 - fox 2.5 projekt

Dreew

Member
2019-11-27 9:11 am
MD
Hi to all.

There is such a Polish 2.5-way project: FOX 2.5 DIY Kit – YB
SB29SDAC-C000-4 + 2xSB 17NBAC35-8 - fox 2.5 - projekt by YB audio & valiant
In this project I would like to install aluminum SB26ADC-C000-4 instead of SB29SDAC-C000-4

I have FRD & ZMA for SB26ADC-C000-4 but I do not have FRD & ZMA for SB17NBAC35-8. Maybe someone has FRD & ZMA for the SB17NBAC35-8 midwoofer?

Maybe someone will be interested in this project and help me to instal the SB26ADC-C000-4 tweeter?

Sorry for my bad English.
 
Hi Dreew,

Your tweeter doesn't seem to have the same sensitivity and that could be the issue. The original design that you linked too has a 4.5ohm resistor before the tweeter to help attenuate it.

If you use your Sb26 FRD and ZMA and then model it with the original circuit components and omit the 4.5 ohm resistor do you get a very accurate reproduction of the original graph, its amplitude, shape and roll of slope? If so I would imagine it could work.

You can use the spl trace tool in VirtuixCAD to copy the original manufacturers PDF data for drivers you haven't got measurement data for. It could be a solution to your problem, if nobody provides you with the files you require.
Sorry I don't have the data, the metal cone Sb speakers are not normally listed in UK, which stops them from being frequently used. Sorry I cant help further.
Cheers, Ray.
 
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Dreew

Member
2019-11-27 9:11 am
MD
Hi.
I found the files, I hope that they are reliable.
I got such a simulation in the Xsim program.
28735019.jpg

These are XSim and FRD & ZMA files, maybe someone wants to make a simulation in another program and he will get a different result.
 

Attachments

  • FOX 2.5 (XSim).dxo
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  • FRD & ZMA.zip
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Dreew

Member
2019-11-27 9:11 am
MD
Of course, it’s best to take driver measurements in baffle through a microphone, but I don’t have that option.
Are there 2.5-way projects with aluminum SB speakers in this forum?

I found several projects where SB26ADC-4 was used
These are 2.5-ways and 2-ways. Here's what the crossover looks like in them.
28735876.jpg

28735877.png
 
Look for a true 3-way design using one aluminum SB17NAC and SB26DAC you can build/copy. Adding a single 12" woofer or dual 8" woofers will produce superior sound compared to a 2.5 way.

Your room and speaker placement will have a large affect on the bass crossover tuning, so consider building a proven aluminum TM and extend the cabinet to support dual SB23NACS45-8 woofers with a final crossover tuned to your room.
 

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  • side 12.jpg
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  • Kronos inspired.jpg
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Your attached Sim with your tweeter in place looks good to me, although with your components there is a steep phase transition around the crossover. I personally try to keep swings more gentle if possible. 30 degrees or so isn't too bad, so maybe I am in the wrong to mention this.

The capacitor and inductor values are good and the use of 1ohm resistor for the tweeter show that it does has enough sensitivity for this design.
If you like lots of high frequency you wont have a means of getting more level that is the only real downside as I see it.

Are you going to try it?
 
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Dreew

Member
2019-11-27 9:11 am
MD
Your attached Sim with your tweeter in place looks good to me, although with your components there is a steep phase transition around the crossover. I personally try to keep swings more gentle if possible. 30 degrees or so isn't too bad, so maybe I am in the wrong to mention this.

The capacitor and inductor values are good and the use of 1ohm resistor for the tweeter show that it does has enough sensitivity for this design.
If you like lots of high frequency you wont have a means of getting more level that is the only real downside as I see it.

Are you going to try it?

Thanks.
I want to try to make a crossover simulation in another program and compare the result.
I would like to try a program that takes into account the calculations of the baffle and cabinet.
 
Have you heard the original design or at least know people who have heard them and asked them for feedback. If it was good design liked by others, the tweeter substitution should still give a good result.

I take the point about baffle and cabinet dimensions and wanting to sim them. I am reasonably sure you wont see to much difference between programmes if they are correctly implemented and your input data is good.

If the original design is what you wanted I am happy it will work, with just one or two changes in the crossover to match your personal idea of what a speaker should sound like in the treble range. That's a bonus of DIY.

If you are going to start with a completely new design then modelling the baffle is one of the fundamentals to make final voicing progress smoothly.

As an observation we can get obsessive about designing and modelling a dream speaker system. I typically spend a day listening to a component change before moving on, or deciding that's good enough.

Whichever way you go with the designs enjoy the experience.
 

Dreew

Member
2019-11-27 9:11 am
MD
I know those who heard this design only in the forum. These aluminum SBs have fast and accurate bass, a fairly transparent sound, and in general they are more than good for the money.
I asked about baffle, because I wanted to try to make the cabinet wider. But you’re probably right, it’s better to leave a proven design and replace only the tweeter.
But I would still try to simulate a crossover in some other program to make sure that the data matches the data that I received in the XSim.
 
I have looked at the original design to remind me about its qualities.
The component list looks good and as you say the SB speakers are more than good for the money. So It seems a considerable amount of time and effort has gone into the design. When you publish a design to sell, I imagine its a very daunting thing as there will always be people who want to pick holes in everything. The big but, is speaker design is about many things, the design aim, cost, your interpretation of the aim, and then listening and tuning to match. Not forgetting rooms will modify every design. As will the number of people in your listening room, record shop or wine bar where you use your speakers

Your Xsim data suggest to me that basically the design should sound good on axis with both speakers basically pointing at the listener. That's according to my criteria and what I currently understand from the graphs.

If you have the time and inclination and you want wider cabinets, it would be interesting to come away from current fashion and go with a 70's style wider baffle. I grew up with wide baffles from the likes of Wharfedale, Celestion, Goodmans, Kef, B and W, Acoustic research, the odd Snell, and B and O designs. So I am pre disposed to them.
Wharfedale Dovedale's , Leak 2060's a more modern Dovedale, Celestion Ditton 44 and Yamaha NS1000s will always bring back happy memories for me. Interestingly they are all sealed three ways if I recall correctly, 12" bass, wide baffle to accommodate the 12" driver 60 litres or so. Midrange and tweeter. One day, maybe next year, I may do a design myself but I haven't landed on the right 12" bass yet. And I do want to try that new Sb dome. Hint!

Consequently the other advice about a three way could be another path to investigate if you want to design something new.
Where you live is there a classic 12" bass unit that was used by everyone in the 70 and 80s in a sealed box. If so buy some good second hand examples and then integrate with SB's latest 3 or 4" midrange in a separate small sub compartment within the box. If you are really lucky Sb will have released their new 50mm dome, then add in your current tweeter, its a good one. With sensible design from yourself it will sing. But can you live with that size and shape of Box.
Good luck.
 

Dreew

Member
2019-11-27 9:11 am
MD
Thanks.
Well, I think that 2.5-way aluminum SB is the first step towards an inexpensive and high-quality speaker system.
Perhaps in the future, I will try to make 3-ways to 12" or even 15" and this will be the transition to the next level.

Sorry for my bad English.
 
I think your decision is a good one.

It would be good to hear from you during the build I am sure there will be many people interested in your progress.

Take your time with the build, if you are not an expert woodworker, take your time or use friends, or a local woodworker to help cut panels. Use plenty of glue to make sure it is well sealed and well stuck together, The two mid bass units will generate a fair pressure in the box so it needs to be strong with any braces well glued and fitted.
Final advice don't forget about your partner whilst you are doing all this.
Cheers.
 
I think if you simply take the dimensions from the cabinet drawing that you have attached, that is all that is needed.

I assume you have defined the baffle size in VirtuixCAD as per the original design, then I think as follows.
x = the centre line position for the bassmids from the reference edge of the cabinet.

Y = Individual centre heights for each driver from the bottom edge of the cabinet

Z = relative front back displacement to each other. Assuming all reference measurements are taken from the tweeter axis with the drivers all mounted as per the design this can then be set to zero. in measurement terms they are all in the same vertical plane on the baffle.

Others will add to this I am sure, especially if I have made a mistake in my assumptions.

A reminder about the baffle cut outs I haven't checked your tweeter dimensions.
Before you cut the recess for the tweeter, don't forget to check it has the same dimensions as the original, you may have to modify the diameter and recess. Its easy to forget this when modifying an existing design and produce a baffle made with the wrong cut-out. Measure twice or more, then cut once. I tend to struggle with woodwork, I didn't do it at school.
 
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