Attic Shaped Studio

#91

Hi Jennifer,

Not trying to hijack your thread, but I REALLY like your speaker stands ! :ahh:

I have been looking for that small footprint, natural wood look and yours have both of those qualities.

Did you make those yourself ? Or, if you bought them WHERE did you get them ?

#92

mysticmonk wrote:[post]2345[/post Not trying to hijack your thread, but I REALLY like your speaker stands ! I have been looking for that small footprint, natural wood look and yours have both of those qualities.

Did you make those yourself ? Or, if you bought them WHERE did you get them ?

Glad you like them! I far prefer them to the metal ones in the newer photos. Since moving the monitors out of the window bay I've had to use the metal ones as the monitors are now at a lower height. When I get a spare moment I'll cut the wooden ones down to the correct size.

I made them myself as I couldn't find anything on sale that fitted all the requirements. The columns are made with stripwood, the base and top from layered shelf wood. Feet are just the little rubber ones you can buy anywhere. I put washers between the base and the feet to bring the columns vertical.

The columns are open at the back to avoid any resonating hilarity a sealed box might give. Cables get concealed in there.

Here's a few photos showing more detail;

I didn't have a router when I made them, so made this wee jig for a jigsaw to cut the circular tops;

Cheers!
Jennifer

#93

An update on the speaker symmetry with new REW tests. The speakers are positioned like this; it's not the end goal, but a temporary measure until soffits can be built. Soffits, a proper hard backed cloud and improved treatment will make a difference to many of the flaws.

Here's the setup at the moment after radiator removal and installation of a full span corner absorber at the bottom left;

In the midst of mixing last week something set off the spidey sense. I flipped L & R on the master buss to check a solo'd electric guitar, and it was much brighter in the left speaker. My initial thought was "oh no, I've been doing this too long today, my right ear is done in!".

But on examination of REW tests I did last week after the more balanced front treatment was installed I noticed the left speaker was overall louder than the right throughout much of the frequency range. The gain on the left monitor was higher, so not surprising in a way. What was surprising was that on tests before the radiator was removed (and so with very unbalanced treatment at the front of the room) the volume of each speaker was equal at the mix position with the left speaker trimmed louder. I remember doing this very thoroughly; made sure the measurement mic and SPL meter were equidistant from each speaker. Verified with measuring tape and pink noise. And indeed, the frequency response through the mid range and highs on both speakers was close.

But since getting the front room treatment more balanced, it was just the left speaker coming across noticeably overall louder (including in the mids and highs) for the first time. Not my ears, phew! Previously, presumably the unbalanced left / right room treatment required the left gain boost to deliver equality at the mix position.

So today I took the monitors off their stands, set them alongside each other and the SPL meter up close and got them very closely matched in gain. I put them back on their stands and double checked the measurement mic for equidistance. Here's an SPL comparison of left and right;

It's far more balanced than previously, and the waterfall for both confirms this;

For some reason that 148Hz null in the right speaker has got much worse - I've no idea why! The frequency of the null moves when I move the speaker back and forward, and I reckon it's reflection based, so possibly an SBIR. The phase diagrams would seem to confirm this;

Why it is in the right but not left is puzzling me. I'm in the middle of a couple of album projects so haven't had much time out to figure it out, alas!

All this has reminded me of something Stuart said about getting the big problems ironed out first, and it'll reveal the smaller ones to you. A concealed imbalance over most of the frequency range is a huge problem! Should've removed that radiator 5 years ago LOL! :-)

Cheers!
Jennifer

#94

That's some interesting testing you got there, Jennifer. the dip does seem to be SBIR related, and it makes sense, but it's hard to explain why you see that on only one side of the room.

By the way, there's an interesting trick you can use in REW to compare speakers: Go to the "All SPL" tab, then open the "Controls" pop-up (far right side of the screen). Click on "Trace Arithmetic". Select the left speaker curve for the "A" reading, and the right speaker curve for the "B"reading. Now select the "A/B" option, and hit "Generate". It will create a new thumbnail on the left column, so go back to the "SPL & Phase" tab, then select that new thumbnail. What you have there is a graph that shows the DIFFERENCE between your left and right speakers. You'll have to scroll down to the 0 dB point, since that's what you are looking at: Wherever the graph is on the 0 dB line your left and right speakers are producing the exact same level for that frequency. Wherever the curve rises above the 0 dB line, your left speaker is louder by that amount, and wherever the line dips below 0 dB, your right speaker is louder by that amount. Ideally, in a perfect room with perfect speakers, the line should be within +/- 1 dB of flat across the entire spectrum, when smoothed to maybe 1/6 octave or so. Here's what a really good room looks like:

, and a different room that's not quite so perfect, but still very, very good:

. That second one is smoothed to 1/3 octave, so that's a bit if a "cheat", but I couldn't find the 1/6 octave version of that. Here's a more typical one, from a decent home studio, at 1/6 octave:

That's something like +/-3 dB, which is still quite decent for a home studio.

Anyway, I thought you might like to know about that "trick", to get a graph that shows the difference between speakers. The key here is to use mathematical division: You divide the left speaker by the right speaker. People think that you have to subtract one from the other to get the difference between them, but that's not correct. Or rather, it is correct, but to subtract logs, you have to divide not subtract! dB scales are logs, so dividing the log values is the same as subtracting the underlying signal values... Sigh! Math! ...

- Stuart -

#95

Just a small update; fortunately I've been occupied with several music projects here, and haven't had time to start the ventilation installation and improve the isolation of the stairwell side wall.

A nice little boost today: I was talking with a neighbour, a retired builder. We live in a small cul-de-sac, and often have good chats. I knew he was behind the planning and development of the cul-de-sac, but found out only today that he and his firm also built several of the houses. The ones he built are similar to ours - identical in the main part - so I described my plans for the studio upgrades to him and asked his opinion. He reckoned they were totally sound, and the additional plasterboard load will be absolutely safe, well within the load margins. Intuitively I had thought this, but it was nice to have the confirmation. He's going to try to find the building plans for our house, which would be amazingly useful before I start those upgrades! Fingers crossed.

Cheers,
Jennifer

#96

Greetings Jennifer,

Yes, it would be great if you could get hold of the plans. Just knowing how much leeway you have with your build (I'm really thinking about the DOORS here) would be very nice indeed.

And you do have good fortune to be working on projects. So many are shut down.

All the best,

Paul

#97

fortunately I've been occupied with several music projects here,

That's the most important news! Making music and making money from your studio is the best thing!

(And having the original plans is pretty useful as well!)

- Stuart -

#98

Hey Jennifer, I don't know if you noticed, but your thread is one of the most popular on the forum! It is about to click over 30,000 views :shock:

Yup, that really is thirty THOUSAND views.
So it seems an awful lot of people are very much interested in what you are doing, and what you have already accomplished.
Thanks so much for helping to make the forum such a great, interesting, and useful place!

- Stuart -

#99

I hadn't noticed Stuart, thank you for pointing it out and for all your encouragement and maintaining the website. I'd better get doing something soon then!

I've received the house plans from my neighbor. They are for the original design, the guy who built the house made substantial modifications to them. Fortunately the floor the studio is on is identical, so a big win there. It has the locations of the joists, rafters, studs and all that stuff. It's a massive boost as I thought I would have to start pulling plasterboard off walls to figure out where these are before drawing up the plans and getting a bill of materials together.

Cheers,
Jennifer

#100

I've received the house plans from my neighbor. ... Fortunately the floor the studio is on is identical, so a big win there.

That's really good news! Lucky you.

That makes it a lot easier to design things, and avoid running into unexpected problems. Or rather, running into FEWER unforeseen problems! Murphy's law says that there will always be some detail out there, waiting to bite you when you least expect it...

- Stuart -

#101

Time to get this show back on the road!

Difficulty getting materials in April last year meant I couldn't get the ventilation installed, and a summer of being cooked. I am determined to get it done before this summer.

Getting access to the narrow part of the roof eaves to mount the silencers on the floor joists was always a bit of a puzzle. A simpler way of mounting the silencers occurred to me though. These silencers are part of the inner leaf, so don't need to be isolated from it, so why not mount them on the wall part of the inner leaf?

The silencers will be made from two layers of 18mm OSB, so will be quite heavy and exert a significant cantilever force when mounted at one end. So I've extended the outer layer into large "dog ears";

These will be attached with beefy screws to an OSB board that is the first layer of the knee wall. This means the silencer won't touch any of the outer leaf at all, nor will it directly touch the house structure.

Fortunately the roof rafters and truss structure around this area is very sturdy;

View from inside the room showing the registers and a layer of plasterboard on top of the OSB.

It all seems reasonable to me, and I'll be using structural OSB3 as these are in the roof eaves. I understand it is very strong. However, I've never worked with OSB before, so thought I would seek comments and a basic sanity check before committing to the design and ordering supplies.

Cheers!
Jennifer

#102

Greetings Jennifer,

Nice to see you're back to construction. I'm thinking about the two layers of 18mm OSB. That will indeed be extremely heavy. The only way I could get my head around the idea of the weight was to think about kitchen cabinets: good ones are 3/4" thick (just a bit less than 18mm). Check with Starlight to see if his silencers are of a similar robustness. I can't remember off hand.

Something in the range of 13-14mm (for each layer) would likely suffice, and would still have plenty of heft.

Just my two cents.

All the best,

Paul

#103

Thank you Paul, your kitchen cabinet comparison is a superb insight. Indeed, these are often mounted directly to a layer of OSB behind plasterboard in a similar way.

I just checked our kitchen and the cabinets are about 18mm, with the sides double layered - an inner cabinet + outer facing. Combined with the shelves the top and bottom is effectively double layered too. They don't protrude as much as the silencer, but on the other hand will be very heavy once loaded with dishes. They've stayed stuck to the walls in the five years we've lived here :-)

I suspect these silencers will be around 50 kg each. Reason for 18mm is to get a close match the floor, which is 40mm thick in total. 22mm of floor board + 18mm tongue and groove wood floor.

I plan to do a similar thing at the rear of the room for some broadband bass absorbers. They'll be almost 600mm deep, filled with light loft roll type insulation;

These will have an outer layer of 18mm OSB, and an inner later of 15mm plasterboard. The floor will be 18mm plywood.

Cheers,
Jennifer

#104

Greetings Jennifer,

They've stayed stuck to the walls in the five years we've lived here

Well now that you've said that, you KNOW what will happen next...

Understood about the match to the floor. Makes perfect sense.

All the best,

Paul

#105

Hi
This looks to be a good plan although you could consider MDF for the inner layers (you may find it cheaper). I've been working with OSB on my building and it's easy to cut and work with. I can also recommend speaking to Just Fans about the fan you'll need, they were very helpful for me. I settled on: https://www.justfans.co.uk/awv-external ... p-121.html

I don't know if it's of any help, but I'm going to have a load of the 'proper' duct liner spare from my build. The company that make it in the UK make it to order and it's a minimum size of 15 meters long. It even came on a pallet! I won't even need half of the roll, I don't think, so if this is of any interest send me a message.

Your sketchup skills are pretty impressive, by the way, I'm afraid I don't have the patience for such detailed work.

Cheers
Gareth

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