Few Questions Before I Start My DINAS Build  

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Luftfeder
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26/10/2019 8:59 am  

I'm an excellent woodworker and engineer and like to do a lot of DIY things ... so basically I'm dangerous on a lot of topics but expert in few ... I did build two different pairs of speakers about 30 years ago, so I figured its about time to do it again. BUT before I get started I had a few confirming / clarifying questions prior to starting my DINAS build.

I want to use a pair of DINAS in my office as bookshelf speakers across the room from my computer from which I will wirelessly steam my audio (Bluetooth or other protocol not yet decided) 

1) please critique my idea of making one DINAS as designed and then making one DINAS as a satellite without the subwoofer driver and plate amp. In the satellite in place of the lower driver I would put a power supply and the streaming receiver (Bluetooth or other). I would use the Plate Amp in the Main DINAS to drive the satellite. Granted, I lose the ability to tune left / right balance but I also don't need two power supplies and the attendant brick and wire management. I would make the box form factor the same so they look like a pair and maybe place a switch and power-on indicator led and antenna or something in the baffle space normally taken up by the woofer driver. IF this does make sense what polarity should be used for the satellite?

2) room placement - I assume these should be placed on the bookshelf with the tweeters below ear level when seated?

3) I have never used a plate amp and have some novice questions on its controls. A) I assume it is OK to switch power on and off at the power supply and just leave the toggle switch in the ON position on the plate amp itself? B) also I assume that once the volumes are set that the knobs don't have to be touched again and the volume can be controlled at the source providing the music? AND so this setup should be done with volume at/near maximum on the streaming source and then tuned to at/near the maximum desired listening volume in the room? I want to make sure I don't have to go to the back of each DINAS to turn them on or to adjust the volume.

4) Would it hurt the acoustics to move the plate amp to the side of the box if I get in a design situation where getting at the back is difficult?

5) IF I end up going with two standard DINAS do you know of any power supply bricks with two power leads coming from them?

Thank you for some guidance before I get started.

David


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bakenia
(@bakenia)
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26/10/2019 9:38 am  

Hi David,

I build the Dinas and i love them. 

Question 1:
I would stick with the original plan; each enclosure its own subwoofer. With 2 subwoofers you get a more complete bass throughout the room and less standing waves. I have connected the Dinas to one of these cheap small bluetooth receivers. Works great. Choose a bluetooth 5.1 receiver. Greater distance, better quality. You could also choose a wifi solution like Google Audio.

Question 2:
Just experiment with the room placement.

Question 3:
You can leave the on/off switch permanent in the on position. You can switch main voltage elsewhere. Leave the volumes to a certain maximum and control the volume outside. That's what i do anyway. 

Question 4: I guess it won't hurt the design to put the plate amp on the side or even on top.

Question 5:
Each Dinas needs its own power supply. The standard power supply is 90 watts. Pick one with at least 20 volts! The plate also operates on 15 volts, but on high volume you get problems.

 

Good luck,

 

Kees


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123Toid
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26/10/2019 11:27 am  

I'll see if I can help answer these.

1. I always suggest building them as designed. dothere are variables that aren't accounted for when you start changing the design.  Could it work? Sure, but if you were going to do that, I would just build the subwoofer separate from the two satellites and make it like a 2.1 system. 

2. With you being that far away from them oh, it's not going to make much of a difference. Keep in mind the further you are away from the speaker the less degree off axis you are. 

3. Everything you said there is correct.

4. You can put the plane amp on the side or the top.

5. I'll take a look a regulated power supply. But that's what you'd be looking for. You could also use a big enough power supply that has enough amperage to power both. Then you would just split the power signal.  I'll get back to you if I find that big enough regulated power supply. if you want to look on your own, you're looking for a 24 volt regulated power supply that can be regulated down to 22 volts.


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123Toid
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26/10/2019 11:38 am  

@luftfeder this one may work: https://amzn.to/2BNo82m it states that can be regulated by plus or minus 10%. So you'll just need a multimeter 2 check the voltage and make sure you're down to 22 volts or lower. Then run a power cord from each one of these to each of the Dinas.


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Luftfeder
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05/11/2019 2:07 pm  

@123toid thank you for the prompt reply and hints on the power supply - likely the way I will go.

Just purchased and downloaded the plans and have a few quick questions as I continue to plan out my project (still don't have a start date but it is fun to plan):

I do a lot of woodworking as a hobby (my most recent project was a pair of matched cherry dressers - each  with 8 solid maple dovetail drawers I crafted myself) so precise and complex work is not an issue for me - neither is left over materials which leads to my questions. I have enough ¾ stock in both baltic birch core cherry veneer plywood and solid maple and cherry to make 2 DINAS...

1) Obviously I need to adjust the outside dimensions by the ¼" thicker stock so the internal volume remains the same. I assume all I need to do is keep the volume(s) the same -- which will mean slight adjustment to the sealed mid-range box and woofer box since the walls separating the two will be slightly thicker and thus reducing the volume if I don't make a slight adjustment?

2) For the port tube itself can I use ¾" material instead of ¼" as long as it stays ½" tall? This will mean the "U-turn" at the back of the box will be turning around stock which is 3 times thicker thus making the tube net ½" longer. One adjustment could easily be to make the top of the port 7.25" instead of 7.75" .  Should I round over the port tube divider at the "U-turn?" to smooth out the curve AND should I place a cove in the corners of the port tube "U-turn thus making the cross section of the tube constant through the "U-turn?"

3) Also for the port tube... assuming I go with a ¾" baffle material this also makes the port tube ¼" longer. Should I adjust the length of the port tube? (could take the 7.75 upper wall of the port tube to 7.25 for the thicker stock used in the port itself and then down to 7.00 for the thicker baffle)

4) since I am planning to use solid material for the baffle I can use a router to round over the opening of the port. Is there a suggested radius for doing this?

5) Using the thicker stock will make the baffle ½" wider. I will plan to flush mount the drivers and either radius or chamfer the baffle as you have. Does a radius vs a chamfer matter on the baffle when it comes to "baffle step" phenomena? You have stopped your chamfer at about the middle of the woofer would it make sense to go slightly lower especially if the baffle is ½" wider?

6) Also in regard to the wider and taller baffle should I mount the mid-range at 3 down and 4 over (adjusting for the thicker box) or should I keep it 2.75 down and 3.75 over which would place it off center (I would make a left and a right speaker in this case) but maintain the ratios you have to the box edge and actually add a distance of 4.25" for the other side of the baffle. This would also take it out of the geometric center of the sealed box it is in. AND should I also move the woofer up to keep the center to center distance between the mid and woofer tight?

These details I am asking about while theoretically correct may only slightly impact the sound quality and may be details one should only pay close attention to in $5,000 speakers. As I am new and not a Hi-Fi guy I won't be insulted if you tell me "you are over thinking this..."

I think I will make the baffle removable which should make wiring easier ... am I not thinking through this correctly?

@123toid ... It looks like you use SketchUp. IF you like I can provide back a model to you (directly and not posted) when I have a final design (based on answers from above)

 

Thanks for your input.

 


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123Toid
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06/11/2019 2:03 am  

Good questions. Let me see if I can answer them.

1. I wouldn't shrink the mid-range compartment due the mood just fitting in there. This will make the subwoofer compartment slightly smaller, but not in a meaningful impactful way.  

 2 and 3 a port that big, you definitely want to round over both sides, to make it nice and smooth. I didn't mock that up, but you just need to make sure the port length remains the same or close to it. if you're unsure of how to measure that, I did a video on it and would be happy to link it here if necessary.

4. Youth ground over the port, depending on what run over bits you can fit in there, the largest you can fit, you could use. Just keep in mind going around the corners of the port might be tricky.

5.  The chamfer is for looks, so you can do whatever design you want and it should not have any meaningful impact on the sound output.

6. Keep the mid-range at 2.75 down as moving this would affect the crossover between the Tweeter and the mid-range.  Then center the drivers on the middle on your material width. 

 

I think they are all excellent questions. You're not overthinking it. There's just some things that you wouldn't know, since you didn't design speaker. I thought they were really good questions.  I'm honestly really excited to see these. It sounds like you have some amazing woodworking skills. I'm sure these are going to come out beautiful.  I hope this helps


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Luftfeder
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23/11/2019 11:11 pm  

@123toid do you recommend any polyfill or any sound dampening foam applied to the interior walls?

thanks again... I'm inching closer to my build

I think when I first considered the project one or more of the drivers was on sale but have gone off ... any suggestions on optimizing shopping timing on P.E.?


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123Toid
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25/11/2019 12:24 am  

@luftfeder

I have built quite a few and haven't needed to use any dampening, but you are always welcome to try some out.  It won't hurt it.  Just make sure to keep it away from the amplifier and the port opening.  

I don't have any suggestions, but maybe this $25 off code can help you.  It will only work for November on purchases over $250: N8ZL44  But that will be a nice savings off the Dinas.


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Luftfeder
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01/12/2019 9:49 pm  

@123Toid  thanks for the discount code. I actually ended up using a Black Friday discount which ended up saving me a little bit more. 

I used the long weekend to make my box:.

8F746957 9A5C 44B8 9C24 D3CD025ED5E2

 

 

in the attached photo you will see two black 3-D printed coves I use to “turn” the port smoothly 

 

question on the baffle and alignment of the tweeter: I assume that when one  cuts a counterbore into the baffle they should match the flange thickness of the respective driver? These two drivers have slightly different flange thicknesses. AND the distance back from the baffle for the mounting of the tweeter is this from the baffle surface assuming the drivers are “inset” and not surface mounted? 

thank you for your continued guidance as I progress. 


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123Toid
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01/12/2019 9:54 pm  

@luftfeder

I love the inserts you made. Really cool.  As far as the questions, the distance is from the front of the baffle assuming you are flush mounting. Otherwise, it would be from the mid.  You should flush mount if you can. 


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Luftfeder
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01/12/2019 10:26 pm  

@123toid

dumb question about terms

Flush mounting nomenclature means to recess the speaker in a counterbore - 3.5 mm deep in this case if I remember?  

just making sure flush mounting doesn’t mean same thing as simply mounting the back of the flange “flush” onto the baffle

 

i do plan to sink the speaker into the baffle so the front of the flange is “flush” with the baffle - my interpretation of flush mounting 


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123Toid
(@123toid)
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01/12/2019 10:28 pm  

@luftfeder

You're right on 😀  it just means the flange of the driver will be flush with the front of the baffle.  Just like the picture at the top of the forum.


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