GALTIS - On request in English - diyAudio
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Old 18th March 2003, 04:14 PM   #1
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Default GALTIS - On request in English

After all requests I have made a buildingdescription off GALTIS in English. Just follow the url and you´ll be there.
http://w1.311.telia.com/~u31119548/galtis/english.htm

Click the image to open in full size.
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Old 18th March 2003, 05:02 PM   #2
cowanrg is offline cowanrg  United States
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those look GREAT! what was the approximate cost on them to build?
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Old 19th March 2003, 05:39 PM   #3
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Introduction

After all questions about GALTIS I decided to try and make an English description off the speakers. English is not a language that I usually discuss loudspeakers in, but I hope that you English-speaking DIY:ers out there still understand what I am trying to say here. This is then the English version off the building description and thoughts behind the construction of GALTIS.



Tweeter

The tweeter in GALTIS is the ”new” Vifa XT25 rinradiator. I has a very vide frequency response and it is a modern tweeter designed for the new discformats, SACD and DVD Audio. This tweeter is used by “Big” names as KRELL, Audio Physic, and more. What I have read is that this is a detailed and good tweeter but that it doesn’t sound that good off axis. For me that wasn’t a problem since hifi is a one man hobby. When I listen seriously to music I have my chair in the sweet spot. After have lived with the Vifa XT25 for 6 months I can now say that it is much better than its reputation and I would gladly use it in coming constructions.

Finally the Vifa XT25 looks really cool, and that isn’t a bad thing……



Midbass & bass drivers

I knew from the start that I wanted to build GALTIS with Scanspeak drivers. I like the way Scanspeak sounds; they have a clean and yet warm sound. You never get tired when listening to speakers with Scanspeak drivers. I started up with 4 Scanspeak 18w/8542 since I have heard a lot off good things about them. I never got them playing the way I wanted and after a friend did some measurements on them I decided to change to Scanspeak 18w/8545 and 18W/8535. I chose the 18w/8535 since they played so wonderful bass in the ProAc clones. I chose the 18W/8545 after reading about other projects and after my friend with the measurements recommended it to me. The 18W78545 suited my constructions well with a wide frequency response and a sensivity that I easily could match the tweeter and bass driver.



Crossover design

I have tried several different filter constructions. Some that internet friends have recommended, I have tried LC Audio series filter, I have done simulations in LSP Lab and I have listened. Friends have been over on listening sessions and I have made changes in the filter during the whole process. I ended up with a simple filter without baffle compensation. The final adjustment was to change the tweeter filer from 3:rd to 2:nd order for a more open and spreading sound.

GALTIS is a 3-way speaker. My intension was that it would be a 2½-way speaker but the bass turned out to boomy for my taste. The sound is more natural and clear with a 3-way filter. The components in GALTIS filter are a little bit better than ordinary. Air core inductors, polypropylene capacitors and Mundorf resistors.

Click the image to open in full size.

Enclosure in 25 mm MDF

There are different schools in constructing enclosures. Some want the enclosure to be as dead as possible and others want the enclosure to “sing along” a bit. I wanted to make GALTIS enclosures different from AKKELIS, ProAc clones. The GALTIS enclosures should be more “dead”. The enclosure is build in 25 mm MDF with internal bracing and inner wall. The whole enclosure is covered with bitumen on the inside so that it will “ring out” quickly. The frontbaffel is made off 25 + 16 mm MDF with epoxy glue to make it even more rigid. The thought is that the drivers, not the baffle should play the music.

GALTIS is divided in two enclosures. One sealed enclosure off 17,3 litre for the tweeter and mid driver and one reflex loaded enclosure off 29,3 litre for the bass driver.

Click the image to open in full size.

Leaning speakers

GALTIS is leaning 7 degrees backwards. This is to get the right time alignment between the drivers. The thought is that the sound should reach the listener in the same time and phase by leaning the speaker this way. Audio Physics, Marten Design and Thiel are some examples of speakers dealing with this “problem” in this way. B&W have their tweeter a bit drawn back on the top of the speaker for the same reason. Others compensate this in the crossover construction and some don’t think of it as a problem at all.

My solution is to lean the speaker 7 degrees backwards. It was a simple solution and I like is aesthetically.



Bassreflex port forward

I have chosen to have the bass reflex port on the front of the speaker. The reason for this is to make the speaker less sensitive to the back wall.

There are lots off theories about where to place the port. Some say that if you place the port on the back you will hear sound coming out off phase. Others say that if you place the port on the front you will hear blow sounds and you may lose some focus in the stereo sound. I have seen and heard amazing speakers with the port on front, back or bottom, so I don’t think there are any true answers here. I chose to have my ports on the front so that I could place the speakers a little closer to the rear walls without getting too much bass.

The bassreflex port is “flared” on both sides.



Tweeter “off axis”

I have placed the tweeters on GALTIS off axis. The reason for this is to reduce the problems with diffractions and with this placement off the tweeter I get a better frequency response. The best solution would have been to place all the drivers a little off axis. This however is a little bit to daring aesthetically.



Damping.

Damping off speakers in not a simple matter. I guess this is something one could experiment with for ages. GALTIS is damped with bitumen on all inner walls expect the front baffle. Behind the mid and bass driver there is a damping called Rock wool, which is used in house isolation. Over the Rock wool there is speaker damping material called Fibrex. Fibrex is used on all inner walls except the front baffle. The sealed enclosure where the mid-driver and tweeter are housed is almost filled with Fibrex. The reflex loaded enclosure is not as well damped as the sealed enclosure.



Well, that’s it. Have fun.



Stefan Bystedt

Göteborg - 2003
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Old 19th March 2003, 10:15 PM   #4
JimmyC is offline JimmyC  New Zealand
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Cool Many thanks.

Thank you Stephan. The beer will be on ice when you get here!

One thing you haven't talked about much is how they sound to your ears. You've said they're a definite upgrade from the 2.5 clones but could you give us your comparitive viewpoint compared with the clones?

J.
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Old 6th April 2003, 06:56 PM   #5
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I think this is the next project I build. I was going to make something with my 8535s and this is a great looking project. I'm sure they sound great.
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