Auratone DIY

[Brian Roth]

Your first sentence describes exactly what they were used for (and also AM car radios).

Yep. Decades ago I was Chief Engineer at a 24 track studio owned by an ad agency. In addition to the Horrortones, I added a (selectable) 3" speaker in the meter bridge, fed by a mono sum from the CR output.

In 2014 I was doing a studio build in Omaha....pretty high end facility. The "principals" were all age 20/30's. I noticed how they and their friends were listening to various stuff on their phones. I mentioned it to the Head Honcho and I suggested checking mixes on a phone. He thought it was a great idea <g>.

Bri

 

[kags]

Today there are a lot of solutions, like Audiomovers, Authentic Audio, and other utilities (even ZOOM) that let you stream your DAW mix to anyone with the URL. I use it for real-time client input during mix revisions, but also to stream to my phone and/or laptop to hear on those devices and headphones connected to them. The modern version of a studio with an FM transmitter for car checks! In fact, I have one audio interface that I keep at home (got it during covid lockdown) that has a Bluetooth transmitter as one of its monitor outputs. The signal reached all the way to may car outside. I could mix in my living room and then run out to the car to hear the mix live over Bluetooth. I know BT is a lossy format, but it's still pretty amazing that it works at all! The interface, if anyone cares, is the MBOX Studio from Avid.

 

[jezzer]

Greets one and all!

Inspired by this post i've just scored myself a pair of GRS 4FR-8 and I'd like to have a go at building a set. I was looking to make it out of MDF using a design based on Adrian Bruce's version as I don't have the tools to miter the ends or do anything fancy with the woodworking. He used 9mm MDF and I'm opting for 15mm so have adjusted the measurements to give an internal volume of 2.23 L.

I had a few questions about the bracing:

• does this need to effectively form an internal box to support the outer walls? See the 3d mockup below for an example.

• Is it essential for the driver to be recessed with the front level with the front wall or can it be attached to the front?

I will possibly try to find someone with a router to curve the top and bottom edges but not sure if I know anyone in the neighbourhood.

Inspired by this forum, I designed a 3d printed version based around a Celestron TF0510.

The designs are available here
https://www.thingiverse.com/thing:4938938https://www.prusaprinters.org/prints/74461-auratone-5c-clone
The links include a PDF giving details for the construction

I took some measurements outside with REW using a Behringer ECM8000 mic (uncalibrated) - the results for amplitude and phase are attached.

Hopefully Wilts is still around. I might try and 3D print one but fill the walls with Plaster of Paris / PVA glue to see what the difference in sound is like!

I've got an ARC calibrated mic at home from version 1 of their room correction software. What software are you all using to measure the performance? Any rules on measuring - outside / inside - distance from speakers etc?

 

[JohnRoberts]

I had a few questions about the bracing:

• does this need to effectively form an internal box to support the outer walls? See the 3d mockup below for an example.

Internal braces are to prevent/reduce flexing in large flat cabinet walls. I don't expect this to be a major issue with small cabinets. In larger cabinets I've seen struts between opposing walls, not framing the edges.

• Is it essential for the driver to be recessed with the front level with the front wall or can it be attached to the front?

IDK maybe look at how other boxes using the same driver handle that.

I will possibly try to find someone with a router to curve the top and bottom edges but not sure if I know anyone in the neighbourhood.

making sawdust is a good way to get you feet wet in DIY audio.

JR

 

[abbey road d enfer]

Greets one and all!

Inspired by this post i've just scored myself a pair of GRS 4FR-8 and I'd like to have a go at building a set. I was looking to make it out of MDF using a design based on Adrian Bruce's version as I don't have the tools to miter the ends or do anything fancy with the woodworking. He used 9mm MDF and I'm opting for 15mm so have adjusted the measurements to give an internal volume of 2.23 L.

I had a few questions about the bracing:

• does this need to effectively form an internal box to support the outer walls?

No. The box is compact enough to support itself.
IMO, if any bracing is deemed necessary (personally, I don't think it is), I woud just install a caul and a pice of elastic material (e.g. high-density foam) between the rear panel and the magnet, of correct size to be under pressure when the speaker is mounted.

• Is it essential for the driver to be recessed with the front level with the front wall

It is not.

• or can it be attached to the front?

Yes. However, you may wissh to add another layer to the baffle in order to make it flush with the speaker. IMO it's not necessary.

I think you're sweating too much on what actually ends up being the proverbial turd. A useful one, though.
I know what I'm talking about, having been the auratone distributor for about 20 years.

 

[DaveP]

• Is it essential for the driver to be recessed with the front level with the front wall or can it be attached to the front?

It is supposed to reduce diffraction effects and it extends the LF response a little, like round corners do to some extent.
But when you think how close they will be to your ears in a near field installation and that the mid range is starting to beam , you may not hear the difference.
The most useful feature of this type of speaker is that they isolate the mid range very well so you can hear the detail.
best
DaveP

 

[JohnRoberts]

It is supposed to reduce diffraction effects and it extends the LF response a little, like round corners do to some extent.
But when you think how close they will be to your ears in a near field installation and that the mid range is starting to beam , you may not hear the difference.
The most useful feature of this type of speaker is that they isolate the mid range very well so you can hear the detail.
best
DaveP

One obvious benefit of small single driver loudspeakers is the lack of any frequency dividing crossover networks. The midrange, critical for evaluating vocals is not compromised by phase shift and imperfect combining due to crossover networks.

JR

 

[abbey road d enfer]

Hopefully Wilts is still around. I might try and 3D print one but fill the walls with Plaster of Paris / PVA glue to see what the difference in sound is like!

RE: 3d printed version
Interesting, but about 40 hours+ for printing it...?

 

[jezzer]

I think you're sweating too much on what actually ends up being the proverbial turd. A useful one, though.
I know what I'm talking about, having been the auratone distributor for about 20 years.

Haha, most likely. Thanks everyone for taking the time to respond.

IMO, if any bracing is deemed necessary (personally, I don't think it is), I woud just install a caul and a pice of elastic material (e.g. high-density foam) between the rear panel and the magnet, of correct size to be under pressure when the speaker is mounted.


However, you may wissh to add another layer to the baffle in order to make it flush with the speaker. IMO it's not necessary.

Excuse the noob question, but what's a caul? Isn't that the clamp to put it all together?

For the elastic material did you mean something like the blue block below? Same question for the baffle.

RE: 3d printed version
Interesting, but about 40 hours+ for printing it...?

I've never attempted anything like this but possibly? I have plenty of filament and a 3D printer I don't make that much use of. I'd try and cut down on the amount of infill by filling hollow walls with plaster of paris and PVA, so long as the walls are able to hold that weight, it should be okay. Just a thought! I'd only do it for one just out of curiosity.

 

[abbey road d enfer]

Excuse the noob question, but what's a caul? Isn't that the clamp to put it all together?

Sorry, I meant a block.

For the elastic material did you mean something like the blue block below?

I have not made myself very clear, did I?
The block should be of any hard material, such as wood, but a piece of elastic material should be inserted in order to regulate the mechanical stress.

I've never attempted anything like this but possibly? I have plenty of filament and a 3D printer I don't make that much use of. I'd try and cut down on the amount of infill by filling hollow walls with plaster of paris and PVA, so long as the walls are able to hold that weight, it should be okay

I've never experimented with 0% infill, so I don't know how it would turn out.

. Just a thought! I'd only do it for one just out of curiosity.

As long as you don't expect too much...

 

[jezzer]

I have not made myself very clear, did I?
The block should be of any hard material, such as wood, but a piece of elastic material should be inserted in order to regulate the mechanical stress.

Thanks. Still a little unclear on the block - being a bit thick, haha. So the elastic material helps to "cushion" the driver and dissipate some of that energy?

Is the position and orientation of the wood block in the image in my post correct or does it support the side walls? And the elastic material goes in between the wood block and the magnet? Is that right?

I must admit I was just going to bung some wool / BAF inside there.

 

[abbey road d enfer]

Thanks. Still a little unclear on the block - being a bit thick, haha. So the elastic material helps to "cushion" the driver and dissipate some of that energy?

Is the position and orientation of the wood block in the image in my post correct or does it support the side walls? And the elastic material goes in between the wood block and the magnet? Is that right?

Correct on both points.

I must admit I was just going to bung some wool / BAF inside there.

This is another subject. Damping material inside the cabinet helps taming standing waves, which result in frequency response anomalies. It also slightly increases the apparent volume. That's because the speed of sound in damping material is slower than in air, so the speaker "sees" a little more volume.
OTOH it dissipates some energy, which results in minor decrease in sensitivity (a small fraction of dB).

 

[Whoops]

I've built a case for a DIY Auratone build but unfortunatly I don't have at the moment photos of the build.

In case it helps in any way:
- the wood used in the Auratones is particle board on older Brown models and seems to be MDF on the black versions after that, check the photos with the brown and black speaker
- I don't remember correctly the thickness, I think it was 8mm but I'm not sure
- there's damping material inside, it's pink, I don't know the name of it, maybe Abbey knows

here are some photos:

 

[abbey road d enfer]

- there's damping material inside, it's pink, I don't know the name of it, maybe Abbey knows

As far as I remember, it's basic rockwool, so not very efficient.

 

[jezzer]

I've built a case for a DIY Auratone build but unfortunatly I don't have at the moment photos of the build.

In case it helps in any way:
- the wood used in the Auratones is particle board on older Brown models and seems to be MDF on the black versions after that, check the photos with the brown and black speaker
- I don't remember correctly the thickness, I think it was 8mm but I'm not sure

Very helpful - thanks!

 

[DFischer]

My two cents on this: The box volume, bracing, and poly fill won't have much impact on the result. I used poly in mine because my dog tore open one of her pillows and I had a lot of the stuff laying around. I didn't notice much of a difference with or without it. With a sealed enclosure and a 4.5" speaker, there won't be any bass, no matter what you do. That's part of the whole point. Worrying about LF resonances or extending the low roll-off down by a dozen or two Hz won't really change how these are used. The biggest impact on the sound IMHO will be the choice of driver. And with a small sealed enclosure, you can swap out drivers to taste without worrying about any design parameters. Sealed enclosures are quite forgiving and you are unlikely to exceed operating parameters or damage your drivers at reasonable listening volumes.

 

[MicMaven]

- the wood used in the Auratones is particle board on older Brown models and seems to be MDF

here are some photos:

Sheesh! Rather nasty glue job, cheap construction - not inspiring me to spend my hard earned brass. therefor. I imagine I can do a neater job in my home workshop.

James

(PS - emphasis on "imagine...")