Getting the room right

[jim1961]

Well, let me start by admitting that there isnt any one right room or way to do a room. But one can do is define what one hopes to attain and see how to get there. For me, I want a well defined soundstage, pinpoint detail and depth. But I also dont want a dry or dead sound. (I am wanting everything, right?)

After spending some time catching up on whats out there, what other people are doing, looking into models and looking at their graphs, I decided on a LEDE / RFZ model applied to a 2 channel stereo environment. No big screen, no surround. Just the basics in a dedicated room taken as far as I can take them. For my application I decided on a 24ms ISD gap @ > -20db with a -8db ISD Termination. The later arriving reflective energy provides a sense of space and liveliness while the ISD gap of 24ms allows for full psycho-acoustic integration of the direct signal.

I have an embedded specular reflector amongst my diffusion making the termination energy arrive from about 110 degrees (0 being directly forward, 180 being directly behind). About the position one would put a rear surround speaker.

Room treatment components: (all DIY)

QRD Diffusers: 4X N13+4, 6X N7, 2X N17
Deflector panels: 22
Absorption panels: 16 (mostly of pink fluffy >10" thick)

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Room size: 15.5W x 25.75L X 8H (vaulted)
Floor: Pier house with OBC over 2x6. carpeted

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Amp: Classe - CA-100
Pre: Passive
Source: Rega - Apollo
Speakers: Jenzen Seas t25 (soon to be) (see https://htguide.com/forum/showthread.php?t=40484), Currently using 2 way (Dynaudio d21af, Vifa P17WJ-00-08 with 2X 10" woofers in 5.9 cu ft vented cabinet +250w amp)

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Having said all this, questions arise.

1) What bandwidth does the termination peak need to be?
2) Ive got a floor bounce at -17db. Is that down far enough?
3) Is there a real difference in getting the ISD gap energy down even lower? (see attachment)

Lets deal with these first

[JonMarsh]

For starters, what are the dimensions of your room, and where are the woofer sources in relation to the floor, rear, and side boundaries? There's more to placement and setup than just controlling early reflections, though I'd say you've got a very good handle on that.

I don't see that there is a lot you can do about the floor bounce- this is fundamentally governed by the geometry of your speaker and listening position, and at -17 dB will have a pretty minor impact on the frequency response at the listening position.

The rest I'll get back to you on- not much spare time today!

Are you familiar with the Cardas concepts for speaker placement? (it looks like you likely are, but I'm just checking- )

[jim1961]

For starters, what are the dimensions of your room, and where are the woofer sources in relation to the floor, rear, and side boundaries? There's more to placement and setup than just controlling early reflections, though I'd say you've got a very good handle on that.

I don't see that there is a lot you can do about the floor bounce- this is fundamentally governed by the geometry of your speaker and listening position, and at -17 dB will have a pretty minor impact on the frequency response at the listening position.

The rest I'll get back to you on- not much spare time today!

Are you familiar with the Cardas concepts for speaker placement? (it looks like you likely are, but I'm just checking- )

I mentioned room dimensions above, 15.5W, 25.75L 8H(variable) (vaulted)

I am familiar with the Cardas concept but found it inapplicable in my particular setup given other constraints.

edit: I just realized that the way I measure may be why other peoples graphs in the early (<3ms) time part of the measurement look better than mine. I measure with the listening chair in place. I hover the mic over the chair from behind at ear level. I am guessing many (most?) take their measurements with the listening chair removed? So some of what I am seeing in early reflective energy is bounce off the chair.

Where the woofer source is now is not where it will be when I get my new speakers. So I am holding off making final room treatments / adjustments until then.

I do have a question regarding speaker position from room boundaries though. While my pic is dated, so this is not obvious, I have a large 5'W 6'H 1.25'D (filled with R19) absorber panel between each speaker and the side wall. In such a case, does the distance from the speaker to side wall matter much given almost no energy from the speaker is able to bounce off of it?

[Carl V]

I do have a question regarding speaker position from room boundaries though. While my pic is dated, so this is not obvious, I have a large 5'W 6'H 1.25'D (filled with R19) absorber panel between each speaker and the side wall. In such a case, does the distance from the speaker to side wall matter much given almost no energy from the speaker is able to bounce off of it?

Yes for the most part. Bass Freq. are long & think of them as pressure waves..not so muck like light rays in a vector analysis drawing. Altho' your Room Trx slow the wave down somewhat.

[jim1961]

Yes for the most part. Bass Freq. are long & think of them as pressure waves..not so muck like light rays in a vector analysis drawing. Altho' your Room Trx slow the wave down somewhat.

Can I use the attached graph as a basis for determining which frequencies and to what degree they bounce off the side wall?