Hi gang.
A guy in the German Visaton Forum did a mod to the Visaton BG20 that is worth sharing here.
Maybe it has been covered but I did not find it with the search engine.
The basic mods like additional magnet on the back, basket damping and felt rings in the center of the voice coil suppose to benefit the BG20 allot but
this mod seems to make the biggest upgrade to the unit:
Applying Dekalin a visco elastic sticky sealing paste onto the ridges of the surround exhibit the following measured results.
First photo is the stock unit
Second with only the inner ridge treated
Third with two ridges treated
A guy in the German Visaton Forum did a mod to the Visaton BG20 that is worth sharing here.
Maybe it has been covered but I did not find it with the search engine.
The basic mods like additional magnet on the back, basket damping and felt rings in the center of the voice coil suppose to benefit the BG20 allot but
this mod seems to make the biggest upgrade to the unit:
Applying Dekalin a visco elastic sticky sealing paste onto the ridges of the surround exhibit the following measured results.
First photo is the stock unit
Second with only the inner ridge treated
Third with two ridges treated
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Which Dekalin? There are many Dekalin products.
Good reduction of second harmonic at resonances, and slightly better frequency response between 350 Hz and 1 kHz. If you have a chance to borrow someone's Dekalin and use it, it is OK. But if you have to buy it, or have to buy and glue additional magnet at back... well, it looks like polishing the turd...
Good reduction of second harmonic at resonances, and slightly better frequency response between 350 Hz and 1 kHz. If you have a chance to borrow someone's Dekalin and use it, it is OK. But if you have to buy it, or have to buy and glue additional magnet at back... well, it looks like polishing the turd...
I can't understand your reasoning.
The highly regarded B200 is basically a sibling of the BG20 with higher BL, a damped surround and cast aluminum frame.
Many prefer the B200 to the reasonably priced 8" Fostex offerings.
With these few inexpensive tweaks the €40 BG20 can reportedly be brought to the B200 level.
What's more important is the educational aspect of the tweak. There are many undamped accordien surround speakers that may benefit from this damping.
The Dekalin used was a wholesale industrial product that can only be bought in bucket form. To be to focused on the specific product used is probably not necessary as other products may exhibit the same characteristics.
The guys over at the Visaton forum are working on finding a substitute for the Dekalin.
Greets Klaus
The highly regarded B200 is basically a sibling of the BG20 with higher BL, a damped surround and cast aluminum frame.
Many prefer the B200 to the reasonably priced 8" Fostex offerings.
With these few inexpensive tweaks the €40 BG20 can reportedly be brought to the B200 level.
What's more important is the educational aspect of the tweak. There are many undamped accordien surround speakers that may benefit from this damping.
The Dekalin used was a wholesale industrial product that can only be bought in bucket form. To be to focused on the specific product used is probably not necessary as other products may exhibit the same characteristics.
The guys over at the Visaton forum are working on finding a substitute for the Dekalin.
Greets Klaus
My reasoning is based on my hands-on experience with both BG20 and B200.
BG20 is OK for a cheap fullrange, I used it in several low-cost-low-expectation type of projects, both in professional reinforcement and home hi-fi. No highs, though (no modification can help here). But if you have to buy full bucket of Dekalin to improve just a few drivers, it is not worth the effort and the extra money.
B200 is especially disappointing - very expensive, no highs and many resonances in the treble. For half of its price, I found Sica 8D1.5CS much better in every possible way.
BG20 is OK for a cheap fullrange, I used it in several low-cost-low-expectation type of projects, both in professional reinforcement and home hi-fi. No highs, though (no modification can help here). But if you have to buy full bucket of Dekalin to improve just a few drivers, it is not worth the effort and the extra money.
B200 is especially disappointing - very expensive, no highs and many resonances in the treble. For half of its price, I found Sica 8D1.5CS much better in every possible way.
There are many tweaks that combined make the BG20 an excellent speaker covering about 7 octaves.
Even just removing the airtight dustcap makes a remarkable sonic difference.
Here is a translation from the one who did this tweak:
"Out of cost reasons the BG20 is not ventilated and that's the main reason for the much higher mechanical losses compared to the B200. By removing the dustcap and therefore getting rid of the air cushion behind it, mechanical Q goes from 3.0 to 4.4 and rms is lowered from 1.0 to 0.67. I never thought that this can be heard so obviously..... "
Even just removing the airtight dustcap makes a remarkable sonic difference.
Here is a translation from the one who did this tweak:
"Out of cost reasons the BG20 is not ventilated and that's the main reason for the much higher mechanical losses compared to the B200. By removing the dustcap and therefore getting rid of the air cushion behind it, mechanical Q goes from 3.0 to 4.4 and rms is lowered from 1.0 to 0.67. I never thought that this can be heard so obviously..... "
For people who who just want to slap a speaker into a enclosure the Sica might be the right choice.
For those who know how to handle a handful of passive components or use DSP wisely
the B200 will be hard to beat for the price.
Really impressive, indeed.
Shows how important a damping surround can be!
For more highs make your own current drive amp. Makes more bass and highs and even lower distortion.
If you do diy cone tweaking and dsp I know you can turn a cheapo driver into a high end system.
Obviously in technic terms.
Here diy cone tweaking mod
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443458
Also done on a Beyma 8agn
Shows how important a damping surround can be!
For more highs make your own current drive amp. Makes more bass and highs and even lower distortion.
If you do diy cone tweaking and dsp I know you can turn a cheapo driver into a high end system.
Obviously in technic terms.
Here diy cone tweaking mod
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443458
Also done on a Beyma 8agn
Attachments
Been following your endeavors with aluminum foil closely and I'm really tempted to try it out.
Have you ever measured if the glue without the foil makes a difference?
I had great success with the Planet10 (Dave/Bud) approach of cone treatment.
With the Fostex 127 model it made a noticeable difference.
Have you ever measured if the glue without the foil makes a difference?
I had great success with the Planet10 (Dave/Bud) approach of cone treatment.
With the Fostex 127 model it made a noticeable difference.
I am not just slapping a speakers into a enclosure, I am a (small scale) manufacturer of custom-made loudspeakers, with passive or active crossovers, plus DSP as needed.
Sica 8D1,5CS is not a perfect speaker, so I am using it with RLC compensation or DSP.
I do know how to handle a handful of passive components - I used three RLC compensations in a attempt to improve the B200, but in spite of that polishing, that turd remains an expensive turd.
After a little detective work found the thread on Visaton forum, the measurements posted in #1 in this thread are coming from post #77 in that thread, interesting read:
https://forum.visaton.de/forum/galerie-der-projekte/26213-bg-20-revisited?p=539689#post539689
https://forum.visaton.de/forum/galerie-der-projekte/26213-bg-20-revisited?p=539689#post539689
@Radian
No I never measured only the glue.
Just tweak first one driver with foil and then make A / B comparison if you have a balance on the preamp.
I always enjoyed the better transient response. With only damping same result is not achievable.
You get the sound high tech drivers usually offer - for "free" as this DIY mod makes simple paper being something completely different.
Hi and zdravo!
Sica 8D1,5CS is much better driver than Visaton BG20, with very low distortion and much flatter frequency response which in most cases do not need any RLC compensation. Peak at 10 KHz appears only exactly on-axis. It disappears off axis even at small angles - you don't need any RLC for that.
BG20 desperately needs DSP/RLC compensation/attenuation at 1.5 kHz (low Q), at 3 kHz (medium Q) and at 9 kHz (very high Q). Also needs some surround treatment to kill unbearable resonances/distortion.
8D1.5CS may needs DSP/RLC compensation/attenuation at 2.1 kHz (high Q) and at 5.5 kHz (very high Q), if my memory serves me well. At the moment I can't find the RLC values, but I will find them later. It is much easier and better to use DSP for that.
Whether you use Visaton or Sica, you must use woofer or two in the same OB, for frequencies below 200 Hz. If you plan to build OB without woofers (which I do not recommend), BG20 will have better low end than 8D1,5CS.
The Sicas have copper Faraday ring on the pole piece reducing distortion.
But my Sica 12d has a veeery thin paper cone so absolute stability of this one could be better. (although I cure that with alu foil tweak)
If the smaller Sicas have thin cones too I understand why Visaton BG20 does better.
But my Sica 12d has a veeery thin paper cone so absolute stability of this one could be better. (although I cure that with alu foil tweak)
If the smaller Sicas have thin cones too I understand why Visaton BG20 does better.
Hi,
Thanks for the answers. I don't want to ruin the thread. I had used Visaton B200 with Eminence Beta 15 on OB, biamped.
B200 was moded (phase plug) which improved the sound considerably. Many listening hours later, Visaton B200 got to its full potential. I have to note that the sound was very amplifier dependant. To me, it sounded best with a transconductance amp (Pass F2), with 15 ohm output impedance and s slight passive EQ. I was happy.
Then, (life circumstances) I changed residence, left everything and started from scratch.
While I could get my B200s again, I am eager to explore other fullrangers.
B20 always intrigued me, because it is cheap enough to experiment and modify it, without crying too much if something goes wrong.
@Sonce:
I am not using full OB (due to the lack of space). There are Monacors SPH250-TC in 60L sealed boxes and they do fine for the bass up to around 300 hz.
So, only the fullrange (Siare 21 CoG3- but they don't make me happy) is on the Open Baffle (Basszilla concept).
While it would be "easy" to spit the money and get a pair of nice and expensive fullranges, in our DIY spirit, it's more fun to play with cheap ones.
That said, I think it would be best to buy both (Sica 8D 1.5CS and Visaton B20), and then play with the mods and compare. Still cheaper than just a pair B200s.
So, thanks for this thread, it's the true diy spirit
Thanks for the answers. I don't want to ruin the thread. I had used Visaton B200 with Eminence Beta 15 on OB, biamped.
B200 was moded (phase plug) which improved the sound considerably. Many listening hours later, Visaton B200 got to its full potential. I have to note that the sound was very amplifier dependant. To me, it sounded best with a transconductance amp (Pass F2), with 15 ohm output impedance and s slight passive EQ. I was happy.
Then, (life circumstances) I changed residence, left everything and started from scratch.
While I could get my B200s again, I am eager to explore other fullrangers.
B20 always intrigued me, because it is cheap enough to experiment and modify it, without crying too much if something goes wrong
.@Sonce:
I am not using full OB (due to the lack of space). There are Monacors SPH250-TC in 60L sealed boxes and they do fine for the bass up to around 300 hz.
So, only the fullrange (Siare 21 CoG3- but they don't make me happy) is on the Open Baffle (Basszilla concept).
While it would be "easy" to spit the money and get a pair of nice and expensive fullranges, in our DIY spirit, it's more fun to play with cheap ones.
That said, I think it would be best to buy both (Sica 8D 1.5CS and Visaton B20), and then play with the mods and compare. Still cheaper than just a pair B200s.
So, thanks for this thread, it's the true diy spirit
Sica 12D1,5CS is bad fullrange driver, with uneven frequency response.
Sica 8D1,5CS has very good frequency response, matched only by the most expensive fullrange drivers. It is simply impossible Visaton BG20 to sound better than 8D1,5CS.
