Best size for recording room? And what acoustic foam to get?


I’ve got two rooms to choose from for setting up the recording equipment. Are these two rooms just about the same, or is one clearly preferable to the other?

And would acoustic foam such as this be fine (retails at 12.49$ / six panels at eBay), or would it be better to invest in something more expensive?

I’m leery about acoustic foam that’s a “good deal” and doesn’t make you gasp. It’s super easy to produce packing foam in about the right shape pass them off as the real thing. Packing foam’s job is to take up room and not weight anything. Acoustic foam’s job is to be heavy and suck up sound.

Is the cellar classic construction with wooden beams holding up the floor above? Use that and then hang furniture moving pads behind you.

Pix 2 and 3 are a stand-alone sound wall I designed. The design is to build four, put a couple of pads on the floor and press record. I’ve used it several times.

You can put double thick pads on the other walls, too. Don’t forget the floor and desk. See first pix and below.

That book and towel thing is a floor vibration isolator. If you have a boom and spider isolation mount…

…you don’t need that, but the pad on the table is still a good idea.

That pix is expensive rubber bands. If you’re handy, you can build one from real rubber bands and PVC pipes.
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There was a recent posting from someone who built a min-studio out of pushed-together PVC pipe. Worked well and knocked down when she was done.

It’s the noise reflection that comes from behind you that is the biggest problem. Make sure that there is a vertical padded screen directly behind the person speaking. Even an old quilt hung over a rack works.
Also, if you can, ensure that there are no parallel wall surfaces, and there is a non-horizontal ceiling. Portable screens can do this.
Then padded acoustic foam is often not necessary.

A studio I once had access to had minimal actual soundproofing (think I remember industrial carpeting) but was intentionally designed with no parallel walls. Even the ceiling was tilted. It worked remarkably well and I sent several good recordings through there.

But it wasn’t portable…

One further note the cellar is less likely to pick up neighborhood and traffic noises. Heavy trucks are a problem no matter where you are.

Ian, famous for the longest thread in the forum history lives at the intersection of Venice and La Brea in Hollywood (a metaphor and a real geographic location). He records at night.


Depending on what you are recording, the recording room does not always need to be acoustically “dead” (no reverberation). More important is that it is acoustically “neutral” (no noticeable resonant frequencies). Many great orchestral recordings are made in places that have very substantial amounts of natural reverberation, but a good orchestral space is one that complements the music rather than detracting. In the days before the “reverb effect” was invented, recording rooms were often designed or chosen to provide a reasonable amount of natural reverb, and even today many of the larger studios have a “live room” that is deliberately “not dead”.

A room that is totally absent of echoes and reverberation is an anechoic chamber. They environment in such a room feels so unnatural that it would be horrible to try and perform for recording.

For recording spoken word, the recording space usually needs to be fairly dead (substantially free of reverberation and echoes). It is very easy to add (artificial) reverberation if needed, but near impossible to remove excessive reverberation.

“L” shaped rooms can be difficult to work with because the space “around the corner” can act like a resonant chamber, often causing a boominess in bass frequencies.

One of the Producers tried to record in an anecoic chamber and had to add hard panels to avoid the “blackness of space” sound.

One of the things fuzzy pads does is give you freedom to record anywhere without paying attention.


would heavy trucks be helped by Steve’s LFRolloff filter? I live in the middle of a huge city, and while I have both double-glazing and a “Victorian padded room”, I can’t get my noise floor under 51-54 and I have always have a spike in my spectrogram at and around 86Hz. If I apply LFRollof filter then compress and Normalise, I can pass ACX Check. But presumably the Compression is regrettable?

would heavy trucks be helped by Steve’s LFRolloff filter?

You can see it working.
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Steve’s Rolloff changes with the “Length” setting. The actual activity is the thin green line, not the heavier blue one. The green line “tightens up” with higher lengths, but the possibility of sound damage goes up.

The filter is designed to suppress both 50Hz and 60Hz, the base power frequencies in Europe and the US, and in effect, elminate everything below them.

85Hs is too close to 100, so no. It won’t have any significant affect.

Is it trucks? Does it come and go with traffic? It might be good to go looking for it rather than throwing in the towel and fix it in post.

Is there a straight line hardware path from your microphone to the floor? That’s generally not a good thing.

For a long time I had Magic Spot in my studio where the hum and noises went away. It was remarkable. A couple of inches any direction—up, down, sideways—and the hum would come back. One day I climbed into my headphones, fired up my tiny field sound mixer, taped my microphone to a stick and went around the room like that guy at the beach with the metal detector. Found it, too. Turns out my powered music bass cabinet doesn’t go off when I switch it off. It stays running spraying low level hum both electrical and sound.

85Hz doesn’t sound important other than possibly that’s the frequency your house “likes.” Rooms and buildings like certain tones. When just the right tone comes by, the room rings like a bell at that tone. It doesn’t have to be metal and it doesn’t have to be shaped like a bell. Rooms and buildings ring, too.

Los Angeles has done some very serious research on making buildings ring in such a way that earthquakes don’t turn them into expensive debris in the street.

Post some of the room noise (Room Tone). 10 second WAV should do it. Scroll down from a forum text window > Upload Attachment > Browse. No filters or effects and don’t “help it.” Just the noise as you normally experience it.


that’s very interesting, thank you. I assumed it was everything under 100. I seemed to be able to pass ACX Check by applying LFRolloff, but only when I found the thread where you advised someone to turn the length up to the maximum.


very kind of you, sir.

That’s just microphone hiss and should respond well to gentle noise reduction.

Voice signals from a microphone don’t start out loud enough to be useful. They start out molecular-level tiny and boosting that voice signal loud enough to be useful is a really big deal. The closer you get to home quality microphones and systems, the less likely that anybody paid any attention to this and the more likely a microphone is to hiss.

This is from a promotional listing for a good quality sound mixer.
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See where it says “Xenyx mic preamps.” That’s a specially designed microphone volume booster intentionally chosen to have low hiss noise.

Hiss is only half of the battle. You can’t whisper the script from ten feet away, either. Overall noise rating is the noise volume compared your voice volume. Mumbling in your beer is not good when you’re presenting into a microphone. Your job is to be louder than the noise.


Thank you ! That least expensive of these Xenyx pre-amps is really cheap in England ( Premium 5 Input 2 Bus Mixer with XENYX Mic Preamp/Compressor/British EQ and USB/Audio Interface by Behringer ) It’s half the price of a Focusrite Scarlett; are they interchangeable? If they are, then would one of these and an SM58 be a useful alternative to a USB Mic for audiobook production?

“Mumbling in your beer” is a perfect metaphor for what I have been doing, hahah ! Maybe if I increase the beer, that will decrease the mumbling :slight_smile:

Overall noise rating is the noise volume compared your voice volume. . Your job is to be louder than the noise.

Thank you so much for this ! I had guessed this but hadn’t found it in any book or any website anywhere. I had been in despair because there is not much I can do about my recording space, and while I can do something about my hardware, I would be onto my 3rd mic in a short space of time, a lav then the USB, and then a third, proper one which is a little painful. But if noise rating is proportionate to voice volume, I can easily speak up ! yay

Unless you have problems with excessive sibilance in your voice, I’d suggest using a mic that is a bit brighter with high frequencies. The SM58 is a terrifically robust stage mic, and can cope with massively high sound levels without being damaged, but they are fairly dull compared with most “recording mics”. For people that live in Europe (including UK), an alternative to an SM58 is the “t-bone MB85 beta” from Thomann (only the “beta” version, not the cheaper non-beta). They look and perform very much like an SM58, but due to a more modern design, have a slightly brighter sound. They are also very robust, and much cheaper than the Shure. For stage use, their power handling, feedback rejection, low end warmth, and handling noise rejection may not be quite as good as a genuine Shure SM58, but it comes extremely close, and the high frequencies have noticeably better clarity (I own several MB85-betas, and a pair of Shure SM58s).

We have to stick to generalities all the way down to hardware recommendations. At that exact instant we need to find someone that owns or has used the hardware and it’s much more difficult.

It makes me nervous when I see listings like “Interface by Behringer.” Who made the rest of it? Designing the enclosure, interconnect and power supplies is not trivial.

Also, working down from Behringer isn’t at all easy. They’re already champions of workable hardware at restrained cost.


I like my Begringer UM2 MicPre.

These are the recommendations from ACX.

ACX Equipment List
Rode NT1a microphone, MBox Mini-2 (no longer available), Fast Track Solo, and Fast Track Duo.
Microphone stand with boom, microphone shock mount and pop and blast filter. Quiet computer.

I believe that’s what this is.

Just to make it even more complicated, I believe the FastTrack requires special software drivers. ACX is not using Audacity nor do they mention it.


thank you so much, Steve. That’s an incredible price for such a good mic !!! in the UK, it’s 1/3 of the price of an SM58. amazing

thank you Koz

Thank you Koz, do you mean this thing? Behringer U-PHORIA UM2 Computer Audio Interface

Yes. I own one of those. I largely stopped using my Peavey PV6 analog mixer for quick sound jobs. Anything the slightest more than one microphone complicated and I need to use a real mixer—and USB adapter. The PV6 is not a USB mixer.

I like that it will supply 48v Phantom Power to a microphone that needs it. That means for the most part it will accept all major XLR microphone types. It also means the UM2 is largely immune to common USB problems.

It has zero latency monitoring headphones as well as being able to play sound from the computer. That means it’s certified for perfect overdubbing should you desire to sing all three Andrews Sisters one after the other.

There is a way to do better quality. The larger Behringer USB devices have MIDAS preamps not XENYX.

But it’s not $30 usd.

There’s one other oddity. I don’t think the UMC204 can record a mono voice. You can force one, but the voice track as performed will be half volume with the same or slightly louder noise. Or you can record stereo with one channel missing. In both cases you’re forced into post production steps missing from the UM2.


That statement is now quite ambiguous because MIDAS have been bought by Behringer.