Round cannot be be easily made with curved sheets of material. You could bend say 7 sheets and glue them all together in a tractrix similar to old style gramophone horn from Victor mechanical record player.
With wood it did, my horn has also can be a horn with round throat filed in square. But that is more problematic to make, need file it round to square like you see on other designs.
You say a fase plug for the bump, do i need place this on start ot the throat?.
Ohh I did find the basreflex ports in akabak.
I was thinking of a bump from the bass injection ports, not the main tractirix throat driver - sorry about the confusion there. Usually when you have an injection (band pass) port, there will be a bump that is caused by a larger volume formed by the cone and horn wall where the port hole is. If you make a 3d form that precisely fits the void formed by the cone and the port but allows air to pass, it will reduce that bump. Modeling clay or 3d printing or filing a block of wood then gluing inside. You can simulate this by playing with the front chamber volume of your bass injection. Also size of injection port also changes this. Making that volume smaller extends the upper bandwidth of the bass injection.
A tangerine style phase plug on the front of the full range driver at tractrix throat will help to smooth the smalll ripples and dips in the higher frequencies and possibly increase sensitivity in HF's so you would need less low freq shelf filter cut.
Use this example from Altec for inspiration:
There is a whole website somewhere that describes a lot of different DIY phase plugs. It's in my 5MR450NDY thread somewhere.
A tangerine style phase plug on the front of the full range driver at tractrix throat will help to smooth the smalll ripples and dips in the higher frequencies and possibly increase sensitivity in HF's so you would need less low freq shelf filter cut.
Use this example from Altec for inspiration:
There is a whole website somewhere that describes a lot of different DIY phase plugs. It's in my 5MR450NDY thread somewhere.
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Good job! Could you please post the figure with a tighter scale, say 60 dB (20 to 80)? And include the phase response! Decreasing the frequency scale to 100-20000 Hz would also increase intelligibility.
/Anton
That is an excellent result! Wow that is nice looking! Just your Visaton FR8 full range driver and a 3kHz -6dB/oct high pass filter resulted in this?
Can you please repost your data on 10dB divisions, from 40dB min to 100dB max? Or even better in 5dB vertical scales, and 10Hz to 20kHz horizontal scale like this for example:
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Thanks, you make me proud haha, I am still a amp builder and not speakers, but learn fast.
How to set REW that way? I did use it not that long, so find out how is still going on.. I still need to change the mic, the mic amp have to be build up because I did use the pc input who clips very easely.
Oke I have found faseplug ways on this site, you mean one of these, filling space give extensions oh HF. I did not see that in akabak? is it not there?
Phase Plugs
The horn has only a 6 dB high pas, just one 6.8 cap in series.
Tomorrow I test, now nabure is home and it is late in the evening here.
Do now efficienty do drop a lot when correcting for good respons.
regards
How to set REW that way? I did use it not that long, so find out how is still going on.. I still need to change the mic, the mic amp have to be build up because I did use the pc input who clips very easely.
Oke I have found faseplug ways on this site, you mean one of these, filling space give extensions oh HF. I did not see that in akabak? is it not there?
Phase Plugs
The horn has only a 6 dB high pas, just one 6.8 cap in series.
Tomorrow I test, now nabure is home and it is late in the evening here.
Do now efficienty do drop a lot when correcting for good respons.
regards
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Yes, that is the website - you found it!
In Akabak all we can do is change the chamber volume for the bass driver - make it smaller to simulate having a volume filler.
Is that upstream before the amp or at speaker level connected to the driver itself? That is a fantastic trick to compensate for the large response at lower frequency with superb simplicity. I really like it.
It is connected on the driver as a simple 6 dB high pass, so between visaton and amp, removed the shelf in amp itsefs. It is a old trick and works fine, but need more tryouts, first I go make the mic amp ready so I can measure with line in, and calibrate the pc soundcard.
But seeing these sim of the speaker with the amplifier shelf filter do I think better then with 6 dB driver high pass, do you agree? maybe it are impedance peaks so I go make an
correction for that to try. Or room modes when measuring just a other way, this is done close to the horn, other is one meter away.
Yes work enough on this fancy horn. It is nice when there is a extra part in akabak script for throat chamber, this acts as a low pass filter and so need filled up, but akabak don't see it already not properly because it predict good graph, or have you put a shelf correction in script?,
regards
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Thanks for making the scale more visible - now we can see how it performs and work on smoothing it out even more. You have cyclic dips which are probably cancellations from different parts of the cone cancelling out with itself, or it may be a non-ideal throat chamber and cross-section. The sharp dip at 1.3kHz corresponds to a half wave distance of 5.17cm or the cross-section of the throat. This means that sound waves from one extreme edge are cancelling with waves from the other edge. This is where a phase plug like the Tangerine style on a CD would help. Higher frequency cancellations are just harmonics of this fundamental one. You can really make this one not as big by not having a sharp edge on the throat. File it with a smooth radius into the driver diameter direction. It will make the dip a lot less sharp. Sharp deep dips like this are not as audible as a 12 dB peak at same frequency.
There is a lot changes when measure with different distances, like very close to one meter.
How did you measure? a lot of distance or close.
Last picture let see what I go try to do, with wood I can play with that, file it in speaker direction and make a faseplug for fill up that space.
regards
How did you measure? a lot of distance or close.
Last picture let see what I go try to do, with wood I can play with that, file it in speaker direction and make a faseplug for fill up that space.
regards
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Nice!!!
That was perhaps the best improvement I have seen from a file job! You are almost there - that is a great frequency response by the way. A 3d printer is what you need for the phase plug - and CAD software. You don't want to block it too much at the throat - maybe just 2 concentric rings with a tapered annular ring? I would just go with what you have now. You did an amazing job given no DSP or PEQ. Just a file and a 6.8uF cap!
Kees, you did an amazing job here and I think it deserves kudos and should be reposted over on multiway forum in one of synergy threads. Those guys will really appreciate what a remarkable result you have managed to achieve with purely passive means.
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That is really impressive!
Is the Visaton connected correctly? You seem to have 180° polarity.
Please post a pic of how it looks like when you look down the throat and make some off axis measurements (0, 15, 30, 45°).
/Anton
My re-post over on your 3d thread worked
Hoping you can help Kees out with a phase plug Onni. 2in x 2in square throat - what can we do? I am sure you have some good ideas...
Thanks,
X
I was planned to build a cnc who can also make that, this machine was meant for pcb milling in future, but pure handjob will do when I go for the faseplug you mention earlier.
But nice to ask somebody who have a 3 d printer, these are still expensive, but go lower now.
I go test a ring file it as the shape of the visaton to test, tomorrow.
I need first a mic amp because I think measurements are not precise enough, a pc mic input is not very lineair I think.
regards
Do yourself a great diy self-favor and buy a USB calibrated mic. You will use it *all* the time and it will make your speakers sound better. No pre-amp for mic needed and will be calibrated in absolute SPL out of the box. The pre-amp and ADC are all in mic head so no noise pickup, no pre-amp to calibrate. A good mic is an essential piece of gear to making good sounding speakers.
miniDSP UMIK-1 is very good and what I use.
There are local places that will print your 3d stl file for a reasonable charge.
miniDSP UMIK-1 is very good and what I use.
There are local places that will print your 3d stl file for a reasonable charge.
Did the measurements for you, however the room give trouble.
I did also switch wires on speaker to see what happens first and second picture.
regards
