Hi,
I am about to make my first attempt at building a sub, well its my first attempt at anything made of wood since I made a coat hanger in woodwork at school. I am using the Shiva in the Adire designed 54 litre enclosure. I'll be using a Redgum 180 watt sub amp. Down the track I'll add a Linkwitz Transform to improve bass extension.
I have managed to pick up from the forum that bass extension is a function of enclosure volume (amongst other things). What I haven't been able to work is whether there is anything 'special' about particular volumes. Do Adire use 54 litres because it has some special mathematical relationship with the Shiva or is it just a convenient size likely to get spousal approval and without too much compromise in bass response? I note it has a Qtc of .707.
The reason I ask the question is that I intend to put the amp into the rear of the enclosure. It will take up less than 2 litres of volume. I was wondering how critical my measurements would need to be to extend the enclosure to accommodate the additional volume of the amp. Can I just approximate it or does it need to be exactly the volume of the amp (which is an irregular shape and my calculus ain't what it used to be). I was planning in just adding an extra 15mm to the enclosure length. Are slight variations in overall Qtc noticable?
One other question. If I add a linkwitz transform circuit later on, can it be in a separate box in the path between the preamp and the sub power amp using RCA connections or must it be an integral part of the amp? This is just not stated anywhere that I can find, even on the linkwitz pages. Apologies if this is just a plain dumb question.
Thanks for your help.
I am about to make my first attempt at building a sub, well its my first attempt at anything made of wood since I made a coat hanger in woodwork at school. I am using the Shiva in the Adire designed 54 litre enclosure. I'll be using a Redgum 180 watt sub amp. Down the track I'll add a Linkwitz Transform to improve bass extension.
I have managed to pick up from the forum that bass extension is a function of enclosure volume (amongst other things). What I haven't been able to work is whether there is anything 'special' about particular volumes. Do Adire use 54 litres because it has some special mathematical relationship with the Shiva or is it just a convenient size likely to get spousal approval and without too much compromise in bass response? I note it has a Qtc of .707.
The reason I ask the question is that I intend to put the amp into the rear of the enclosure. It will take up less than 2 litres of volume. I was wondering how critical my measurements would need to be to extend the enclosure to accommodate the additional volume of the amp. Can I just approximate it or does it need to be exactly the volume of the amp (which is an irregular shape and my calculus ain't what it used to be). I was planning in just adding an extra 15mm to the enclosure length. Are slight variations in overall Qtc noticable?
One other question. If I add a linkwitz transform circuit later on, can it be in a separate box in the path between the preamp and the sub power amp using RCA connections or must it be an integral part of the amp? This is just not stated anywhere that I can find, even on the linkwitz pages. Apologies if this is just a plain dumb question.
Thanks for your help.
Hi Allen
Try downloading one of the free graphical box design packages, it is much easier to see Q changes than to describe them, and it will also give you an idea of why Adire chose the box they did.
Normally, you can get away with about 10% variation in box volume before you have problems with response, so putting your amp in the box should be no problem, ( but make sure it is in a seperate compartment!).
Yes, you can add the LT circuit in later at line (signal) level.
Good luck with your project😉
Try downloading one of the free graphical box design packages, it is much easier to see Q changes than to describe them, and it will also give you an idea of why Adire chose the box they did.
Normally, you can get away with about 10% variation in box volume before you have problems with response, so putting your amp in the box should be no problem, ( but make sure it is in a seperate compartment!).
Yes, you can add the LT circuit in later at line (signal) level.
Good luck with your project😉
Hi pinkmouse,
Thanks for your help. Can I just ask a couple more to make sure that I have it. When you say "( but make sure it is in a seperate compartment!)", does it need to be completely sealed from the rest of the sub enclosure, say to the extent that there needs to be some sort of sealant around the cable hole?
Can you take the time to explain why a separate compartment is necessary?
Also, when you say "you can add the LT circuit in later at line (signal) level", this means that I can run "Sub out" on my preamp to an RCA input on the circuit, RCA output from the circuit to RCA input on the amp (ie. but not to a speaker level input).
Thanks again.
Thanks for your help. Can I just ask a couple more to make sure that I have it. When you say "( but make sure it is in a seperate compartment!)", does it need to be completely sealed from the rest of the sub enclosure, say to the extent that there needs to be some sort of sealant around the cable hole?
Can you take the time to explain why a separate compartment is necessary?
Also, when you say "you can add the LT circuit in later at line (signal) level", this means that I can run "Sub out" on my preamp to an RCA input on the circuit, RCA output from the circuit to RCA input on the amp (ie. but not to a speaker level input).
Thanks again.
bigkid said:
Well, thats the way I would do it anyway. The extra compartment basically helps to isolate the vibration sensitive circuitry of the amp from the speaker compartment. It also means you do not have to make sure all your heatsinks, input panels, sockets etc. are sealed. You need to seal that compartment in order so as not to upset the volume of the main box.
Yup, you got it😉
bigkid said:
Well, thats the way I would do it anyway. The extra compartment basically helps to isolate the vibration sensitive circuitry of the amp from the speaker compartment. It also means you do not have to make sure all your heatsinks, input panels, sockets etc. are sealed. You need to seal that compartment in order so as not to upset the volume of the main box.
Yup, you got it😉
Hi Allan
Sounds like you are on the right track.
Where are you getting the Redgum amp from and at what price?
Mick
Sounds like you are on the right track.
Where are you getting the Redgum amp from and at what price?
Mick
Hi Mick,
I got it from John Woodhead at Accoustic Concepts in Victoria. He does the base model RGSW-1 for A$395 and $17 freight. He emailed me a detailed price list for the amps and Adire speakers. If you email me I will send a copy to you.
Audio Concepts are here: www.acousticconcepts.com.au
I got it from John Woodhead at Accoustic Concepts in Victoria. He does the base model RGSW-1 for A$395 and $17 freight. He emailed me a detailed price list for the amps and Adire speakers. If you email me I will send a copy to you.
Audio Concepts are here: www.acousticconcepts.com.au
Thanks Allan
I'll e-mail Acoustic Concepts if I want more info. Just interested for future reference.
BTW, putting the amp in a separate compartment is probably the best way to do it, but if its a hassle, I wouldn't be too worried about mounting it in the side of the box, like almost every one does. The ear is pretty insensitive to distortion of low frequency sound, so you're very unlikely to hear any microphonic effects caused by sound and vibration from the box. If you were talking about the midrange, then I'd be more inclined to agree with Pinkmouse. Just my opinion, and not backed by any experimentation or a 5 year warranty 😉 .
Also - given that you are using a sealed enclosure, I wouldn't be worried about the volume of the amp at all. It will increase the Qt, but only very slightly (maybe from 0.707 to 0.717, which is insignificant).
Mick
I'll e-mail Acoustic Concepts if I want more info. Just interested for future reference.
BTW, putting the amp in a separate compartment is probably the best way to do it, but if its a hassle, I wouldn't be too worried about mounting it in the side of the box, like almost every one does. The ear is pretty insensitive to distortion of low frequency sound, so you're very unlikely to hear any microphonic effects caused by sound and vibration from the box. If you were talking about the midrange, then I'd be more inclined to agree with Pinkmouse. Just my opinion, and not backed by any experimentation or a 5 year warranty 😉 .
Also - given that you are using a sealed enclosure, I wouldn't be worried about the volume of the amp at all. It will increase the Qt, but only very slightly (maybe from 0.707 to 0.717, which is insignificant).
Mick
Cheers Allan...your starting out with a good concept....once you get this going and your veins get filled with adrenalin...you`ll keep needing a fix to build some more projects......lots of support here for anything you want to do.......and on a final note....we all have quandries here...questions are not stupid...they show interest
DIRT®
DIRT®
I'm also building a sub based on the Adire Shiva (142.5 L BR).
I already had a seperate room planned for the amp and when I got it, the manual recommended the amp to be placed in a seperate room. This to avoid any strain on the components of the amp, caused by the enormous air-pressure 😉
I already had a seperate room planned for the amp and when I got it, the manual recommended the amp to be placed in a seperate room. This to avoid any strain on the components of the amp, caused by the enormous air-pressure 😉
Hi Bigkid
How's the project going? Having already built some floorstanders, I'm looking at doing something very simular t owhat you've outlined.
I'm familure with the Redgum Amp, but I was wondering what driver you were using, and how much it cost here in Australia.
Thanks!
How's the project going? Having already built some floorstanders, I'm looking at doing something very simular t owhat you've outlined.
I'm familure with the Redgum Amp, but I was wondering what driver you were using, and how much it cost here in Australia.
Thanks!
Hi Mike,
Little slow on the project I am afraid, got to juggle it with painting the house. I am going with the Adire Shiva 12inch driver using their 55 litre design:
http://www.adireaudio.com/Files/SealedShivaApplications.PDFbox
I intend to use a linkwitz transform circuit with the following components
C1 = 0.51 uF
C2 = 0.047 uF
C3 = 0.22 uF
R1 = 25.4 kOhm
R2 = 65.5 kOhm
R3 - 63 kOhm
to give me a Q of .707 and, with the Redgum's 3db boost per octave below 20 Hz, a -3db response at somewhere just below 20Hz (if I have the maths right of course). I found this site helpful in getting my head around this stuff, the linkwitz site is too technical for me: http://sound.westhost.com/linkwitz-transform.htm
You can get the Shiva from John Woodhead who appears to be the local importer at: www.acousticconcepts.com.au for about $272 + $17 delivery. He also has the Redgum for about $395. The Shiva seems to go for about US$125 (in the US). Probably cost about A$250 to get it over the net with delivery so I'll get mine locally from John in the next couple of weeks. Worth the extra $22 for piece of mind.
I got several helpful emails from Adire and from John Woodhead about the design. Happy to send them on to you if you wish.
Good luck.
Little slow on the project I am afraid, got to juggle it with painting the house. I am going with the Adire Shiva 12inch driver using their 55 litre design:
http://www.adireaudio.com/Files/SealedShivaApplications.PDFbox
I intend to use a linkwitz transform circuit with the following components
C1 = 0.51 uF
C2 = 0.047 uF
C3 = 0.22 uF
R1 = 25.4 kOhm
R2 = 65.5 kOhm
R3 - 63 kOhm
to give me a Q of .707 and, with the Redgum's 3db boost per octave below 20 Hz, a -3db response at somewhere just below 20Hz (if I have the maths right of course). I found this site helpful in getting my head around this stuff, the linkwitz site is too technical for me: http://sound.westhost.com/linkwitz-transform.htm
You can get the Shiva from John Woodhead who appears to be the local importer at: www.acousticconcepts.com.au for about $272 + $17 delivery. He also has the Redgum for about $395. The Shiva seems to go for about US$125 (in the US). Probably cost about A$250 to get it over the net with delivery so I'll get mine locally from John in the next couple of weeks. Worth the extra $22 for piece of mind.
I got several helpful emails from Adire and from John Woodhead about the design. Happy to send them on to you if you wish.
Good luck.
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