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Viawave GRT-145 - a Russian magnetostatic planar tweeter
Viawave GRT-145 - a Russian magnetostatic planar tweeter
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Old 20th December 2017, 06:44 PM   #1
Juhazi is online now Juhazi  Finland
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Default Viawave GRT-145 - a Russian magnetostatic planar tweeter

www.viawave.ru

It has closed rear chamber which correts the problems with distortion and ragged response. Sensitivity is a bit on the high side because of the waveguide, but is that a problem really?
Click the image to open in full size.

Troels Gravesen has some units and has already tested them and made some speaker plans for it

"Overall frequency response is flat, for my measurements a bit flatter than suggested by Viawave. Measurements suggest 95-97 dB sensitivity in the 1-3 kHz range rising some 100-102 dB sensitivity from 4 kHz to 18 kHz. Quite impressive although I would prefer a higher impedance and lower sensitivity as most speaker constructions rarely require more than 88-92 dB sensitivity. This would also save quite some money in good capacitors for the crossover.
Click the image to open in full size.

Distortion is very low, even down to 1 kHz @ 2.8V (100 dB) and suggest even an LR2 filter at 2 kHz may be possible, not a common feature of most smaller ribbons.
Click the image to open in full size.

Impedance is fairly flat and makes crossover work easy. I have simulated the ribbon with four of my constructions and this suggests easy implementation. Due to depth of the ribbon, only modest stepped baffle may be necessary."
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Old 21st December 2017, 06:16 AM   #2
Calvin is offline Calvin  Germany
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Hi,

they claim a sealing between diaphragm and the magnets, but in their Replacement-Repair-pdf there is no seal to find.
Is it a translation error that mixes the special diaphragm shape with a seal or is it simply a marketing misinformation?

jauu
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Old 21st December 2017, 07:42 AM   #3
Juhazi is online now Juhazi  Finland
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I attached wrong picture, that is GR850 and it has just felt in rear chamber. The GRT145 is claimed to have mylar strips that are U-shape. Perhaps the service pdf just lacks them, patent pending?

This is GRT145 with flat front plate.
Click the image to open in full size.

The earlier model GR850 has waveguide and the response is perhaps easier to implement in passive systems
Click the image to open in full size.
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Old 22nd December 2017, 04:48 AM   #4
alexberg is offline alexberg
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Quote:
Originally Posted by Calvin View Post
Hi,

they claim a sealing between diaphragm and the magnets, but in their Replacement-Repair-pdf there is no seal to find.
Is it a translation error that mixes the special diaphragm shape with a seal or is it simply a marketing misinformation?

jauu
Calvin
Hope this helps
In "VK" "FB" and the site itself, the only mentioning of the seal per say is:
"the gap between the magnets' poles and a ribbon is sealed by U-shape suspension made of PET film ..."
Claims are lower distortions higher efficacy and no acoustical "short circuit".
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Old 26th December 2017, 01:51 AM   #5
tuxedocivic is offline tuxedocivic  Canada
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These tweeters are quite good. I just recently got a pair to test and plan to build a 3 way with them. My test results are similar to Troels here: YouTube
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Old 26th December 2017, 03:44 AM   #6
DeltaStar is offline DeltaStar  Canada
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Tux, What did they set you back CDN
Al
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Old 26th December 2017, 03:07 PM   #7
tuxedocivic is offline tuxedocivic  Canada
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They arent cheap. They're $225 USD each and then shipping was about $50 USD and that is how much was on the mail sticker too. I think he must have put good insurance on them, but they're pretty hefty too.
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Old 26th December 2017, 07:23 PM   #8
R-Carpenter is offline R-Carpenter  United States
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Quote:
Originally Posted by tuxedocivic View Post
They arent cheap. They're $225 USD each and then shipping was about $50 USD and that is how much was on the mail sticker too. I think he must have put good insurance on them, but they're pretty hefty too.
No insurance. Shipping from US to Canada is pricey. They are heavy tho. Like 3lb each or 1.3kilo.
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Old 26th December 2017, 07:30 PM   #9
Shaun is offline Shaun  South Africa
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Viawave GRT-145 - a Russian magnetostatic planar tweeter
Quote:
Originally Posted by tuxedocivic View Post
My test results are similar to Troels here: YouTube
Ah! That's you! I just discovered the channel recently. Thanks for this.
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Old 26th December 2017, 09:01 PM   #10
tuxedocivic is offline tuxedocivic  Canada
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Originally Posted by R-Carpenter View Post
No insurance. Shipping from US to Canada is pricey. They are heavy tho. Like 3lb each or 1.3kilo.
Ok I wasnt sure if it was because of insurance or weight. They came pretty quick though.
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