[Basil Plumley]

I have run the Audyssey on my Onkyo 875 a few times and it seems pretty accurate with the distances, very rarely gets the crossovers right and is always about 10db out on the levels compared to my Radioshack analogue SPL metre...

I understand the principles of Audyssey and how it works and what it does. They claim that they don't actually set the crossover in the first place and that the distances are time alligned and not actual measurements - that's why my question revolves around the levels more than anything else.
Audyssey claim to be accurate to +/- 2db from reference level - but every time I check the levels against my SPL, they are all the same but at least 8db below 75db...the fact that they are all the same makes me believe that the Audyssey is probably the more reliable source - bearing in mind that my SPL is actually about 13 years old and was purchased from Tandy when they were still around!

[namuk]

all my speakers measure 72Db after Audyessy using the Radio Shack Digital Meter (there 1Db out) from what i read in reviews and tests's , but this meter does me due to easier reading display.

the sub is around 73Db ..

[24 P]

Basil, I would be using the SPL, as I find AVR calibration tools somewhat a mixed bag of results.
Calibrate with Adyssey, then use the SPL metre to fine tune..
I found that on a Pio LX51, using calibration tools, the EQ was fine, but I found that the rears where to quiet and centre a bit soft..
I had to calibrate by ear and made sure the client was happy..
Hope this helps..

[Avi]

Originally Posted by Basil Plumley

I have run the Audyssey on my Onkyo 875 a few times and it seems pretty accurate with the distances, very rarely gets the crossovers right and is always about 10db out on the levels compared to my Radioshack analogue SPL metre...

I understand the principles of Audyssey and how it works and what it does. They claim that they don't actually set the crossover in the first place and that the distances are time alligned and not actual measurements - that's why my question revolves around the levels more than anything else.
Audyssey claim to be accurate to +/- 2db from reference level - but every time I check the levels against my SPL, they are all the same but at least 8db below 75db...the fact that they are all the same makes me believe that the Audyssey is probably the more reliable source - bearing in mind that my SPL is actually about 13 years old and was purchased from Tandy when they were still around!

Why not ask Chris Kyriakakis of Audyssey on this forum for his advice http://www.avsforum.com/avs-vb/showthread.php?t=795421.

It's a good forum that is frequented by some knowledgeable industry people such as Chris Kyriakakis (Audyssey co founder with Tomlinson Holman of THX fame) and Roger Dressler who was Dolby's R&D director for many years.

AVI

[Pulse1]

The only thing i would trust Audyssey for is the EQ. As the levels, distances, crossovers are set by the Amp/Reciever etc so if these are wrong then it's them to blame and not Audessey I had to reset crossovers and measure speaker/sub distances with a tape measure and then recalibrate all my speaker and sub output levels with my SPL meter after using Audessey as my Denon AVR-3808 Reciever got them all wrong It's the Amps/Recievers that get them wrong and not Audessey

[Basil Plumley]

Originally Posted by Avi

Why not ask Chris Kyriakakis of Audyssey on this forum for his advice "Official" Audyssey thread. - AVS Forum.

It's a good forum that is frequented by some knowledgeable industry people such as Chris Kyriakakis (Audyssey co founder with Tomlinson Holman of THX fame) and Roger Dressler who was Dolby's R&D director for many years.

AVI

Yeah I've been a member over there for years Avi under my real name...had a trawl through that and a decent size thread at hometheatreforum as well - seems that the rule is that Audyssey is pretty accurate when it comes to the levels - reading deep into what Chris says, it seems that the only part that Audyssey really do wash their hands of is the crossovers - seems they even admit to the sometimes stupid subwoofer distances that people get - .5m away or in next doors garden sometimes! All to do with time alignement...I get the crossover problems but it's easy for me - all my speakers (except my sub) are THX certified so they go to 80hz - I leave the distances alone due to the time alignement claim though. However, adjusting the levels will upset that time alignement distance setting as I see it - won't it...

Come back Yamaha DSP-A1 - all is forgiven!!

[amioa]

class 1 sound level meters are accurate to 1dB, class 2 meters are up to 3dB out, and anything else can be up to 5dB out.

[Basil Plumley]

Originally Posted by amioa

class 1 sound level meters are accurate to 1dB, class 2 meters are up to 3dB out, and anything else can be up to 5dB out.

How can you tell what class your particular model is? I have 2 - the Radioshack analogue one and a Phonic personal audio assistant...the 5db thing would make sense.

[namuk]

The Audyssey setup is down to the room and mic placement , works well for me for Distances, even the this Audyssey | Home Theater | Sub Equalizer sets the Db levels (72db) to the same as built in Avr version from what i have read.
i just Calibrate each speaker to 75Db and sub around 76-78Db everything else i leave..

[Avi]

Originally Posted by Pulse1

The only thing i would trust Audyssey for is the EQ. As the levels, distances, crossovers are set by the Amp/Reciever etc so if these are wrong then it's them to blame and not Audessey I had to reset crossovers and measure speaker/sub distances with a tape measure and then recalibrate all my speaker and sub output levels with my SPL meter after using Audessey as my Denon AVR-3808 Reciever got them all wrong It's the Amps/Recievers that get them wrong and not Audessey

I'm not sure how the AVR based versions work but versions that use PC calculations and a pro measuring kit base the EQ filters on crossover points/trims/distance for each speaker derived from the measuring. You then enter the distance/crossover/trim numbers manually into the AVR/Pro Pro etc. If you change these values and use different values to those indicated by the software the EQ filters will be inaccurate.

AVI

[amioa]

Originally Posted by Basil Plumley

How can you tell what class your particular model is? I have 2 - the Radioshack analogue one and a Phonic personal audio assistant...the 5db thing would make sense.

class 1 and class 2 meters come with certificates to show their class, radio shack and cheap ebay items generally are not classed but there are a few that claim to be.

[rickardl]

Well, I think I can shed some light on why your TX-SR875s are not calibrated to 75dB±2dB after Audyssey setup.
The early receivers, not only Onkyo's, used a microphone which was not manufactured by Audyssey but by someone else.
The 2007 Onkyo models all use the same type of mic which shaped like a hockey puck. Besides having a bad shape which causes HF reflections from the base, it is not that good really.
The mic sensitivity was not controlled well enough by the manufacturer to allow Audyssey to make absolute level measurements.
In later models that use the Audyssey mic, tower shaped, it is possible to do that.

Here are some of saved notes about Audyssey levels:
When running autosetup (Audyssey). use all eigth positions where the first one is in the middle of your listening area.
Then in the menu for Level Calibration, make sure none of the trim levels are at -12 or +12 dB (–15 to +12 dB for the Sub). If they are, there is a) something wrong with a speaker or b) a speaker is either too sensitive or too non-sensitive. If b), it is no big deal, that can be accomodated.
If you want to verify the levels with a SPL Meter, set it to C-slow, 70dB, and to measure 75dB±2dB with the internal test tones from the receiver at the exact same place where you placed the microphone for the first measurement reading.

SPL Meters should only be used with test tones such as narrowband noise (500 Hz to 2000 Hz) so that it is not susceptible to room effects.
Sine tones (non narrowband noise) are so prone to standing waves that a single position SPL meter measurement can be off by 10-15 dB.
Therefore, SPL meters can not be used to set the subwoofer level because of the sensitivity to standing waves. The only way to do that correctly is with a spectrum analyzer. Audyssey uses a spectrum approach to determine the levels.

So, where does that leave you? Audyssey does not set the trims for reference volume and you can't use the SPL to set the level of subwoofer...
Well, maybe if you measure 72dB from your fronts after Audyssey, up the trim of all speakers including the sub with the same 3dB without trying to set the level of the subwoofer with the SPL.
For that reasoning to work, I assume Audyssey sets the balance between all speakers correctly but not to reference level.
Makes sense?

[Basil Plumley]

Makes perfect sense really - thanks. Looks like I need to get my hands on one of the new mics then...

I did a lot of reading last night on this and there is a lot of mention of "reference level" and it actually states it as "75db"...with the majority of Onkyo receivers carrying Audyssey being THX certified, you would have thought the emphasis would have been on getting the levels to "reference level"...

[paulst10]

SPL metres have correction values for low frequencies (do a search) so you can measure quite accurate and it's the tool of choice for many subwoofer enthusiasts using REW and has been for a long time

An amps internal subwoofer test tone is around 40 - 60hz ish, and if you have a flatish responce any SPL readings shouldn't vary that much on the needle, but if that reads 75db on the metre it could require around a 2db correction as it really is around 77db.

Here is a chart where the correction values have already been inserted, you take readings for each given frequency using a test tone disk (download in the subwoofer forum) then plot them in the RAW SPL tabs and it will apply the correction value automatically giving you the accurate SPL This is for the RS 4050 model, but most RS models are similar.

When frequencies become lower the less accurate the metres are though, around 20hz a reading of 73.4db on the RS metre is actually 80db corrected, and if anyone can manage 10hz without distorting and get a decent SPL reading .. add 16.9db for the correct value

Edit: must have missed this first time round

bearing in mind that my SPL is actually about 13 years old and was purchased from Tandy when they were still around

That's the problem IMO you need a new one mate

[rickardl]

Originally Posted by Basil Plumley

Makes perfect sense really - thanks. Looks like I need to get my hands on one of the new mics then...

I did a lot of reading last night on this and there is a lot of mention of "reference level" and it actually states it as "75db"...with the majority of Onkyo receivers carrying Audyssey being THX certified, you would have thought the emphasis would have been on getting the levels to "reference level"...

Please note that you can't switch microphone!
The mics are completely different and the calibration curves that Audyssey build internally will throw off the frequency response measurements.
You must use the mic that came with your receiver.
So, do not use any other mic because it will have a different internal calibration and the frequency response measurement will be wrong.

[rickardl]

Originally Posted by paulst10

SPL metres have correction values for low frequencies (do a search) so you can measure quite accurate and it's the tool of choice for many subwoofer enthusiasts using REW and has been for a long time

An amps internal subwoofer test tone is around 40 - 60hz ish, and if you have a flatish responce any SPL readings shouldn't vary that much on the needle, but if that reads 75db on the metre it could require around a 2db correction as it really is around 77db.

Here is a chart where the correction values have already been inserted, you take readings for each given frequency using a test tone disk (download in the subwoofer forum) then plot them in the RAW SPL tabs and it will apply the correction value automatically giving you the accurate SPL This is for the RS 4050 model, but most RS models are similar.

When frequencies become lower the less accurate the metres are though, around 20hz a reading of 73.4db on the RS metre is actually 80db corrected, and if anyone can manage 10hz without distorting and get a decent SPL reading .. add 16.9db for the correct value

In an anaechoic room, you should be able to use the compensation charts
for measuring low frequency sounds
but in a real room with reflecting walls, floor and ceiling, standing waves
will heavily influence the readings and cause huge peaks and dips, based
on your room dimensions, which will vary greatly depandant on where you
place the SPL.
But If you really want to use the SPL for setting the level of the subwoofer,
be sure to apply the compensation charts and take eight different readings
from the same positions where you placed the mic for Audyssey setup
and then average the results.

[Basil Plumley]

Originally Posted by rickardl

Please note that you can't switch microphone!
The mics are completely different and the calibration curves that Audyssey build internally will throw off the frequency response measurements.
You must use the mic that came with your receiver.
So, do not use any other mic because it will have a different internal calibration and the frequency response measurement will be wrong.

I've just come off the phone to a good friend of mine who is a THX certified techie - and happens to work for Onkyo...
He put me right there as well - something else he mentioned was horizontal array - my Jamo D6 speakers are on the vertical and not the horizontal which requires different mic positioning than vertical speakers apparantly. He wouldn't tell me what was different as he like me to find out for myself...git.

[paulst10]

Originally Posted by rickardl

In an anaechoic room, you should be able to use the compensation charts
for measuring low frequency sounds
but in a real room with reflecting walls, floor and ceiling, standing waves
will heavily influence the readings and cause huge peaks and dips, based
on your room dimensions, which will vary greatly depandant on where you
place the SPL.
But If you really want to use the SPL for setting the level of the subwoofer,
be sure to apply the compensation charts and take eight different readings
from the same positions where you placed the mic for Audyssey setup
and then average the results.

Audyssey should have attempted to iron out any peaks in the FR and made time domain corrections reducing ringing in the lower frequencies, so should be better than any pre EQ readings

Audyssey only uses the first position to set speaker levels, distance and obviously EQ, so you wouldn't need to take 8 different readings with the SPL metre as you are only 'checking' what Audyssey has done with regard to speaker levels (it's first reading) using the the amps internal tones

Edit: neatly inserted, (borrowed) from Namuk's link

1. Audyssey uses the first measurement position to calculate the speaker / subwoofer level and distance settings, so the microphone should be placed in the primary seating position.

[namuk]

he saw your number come up Basil ..
you could have a read at this AVS Forum - View Single Post - "Official" Audyssey thread.

most of the Audyssey Faq section was updated due this, good read also and you can download the Guide at bottom as well and print off (it is Microsoft Word format).

[Basil Plumley]

Originally Posted by namuk

he saw your number come up Basil ..
you could have a read at this AVS Forum - View Single Post - "Official" Audyssey thread.

most of the Audyssey Faq section was updated due this, good read also and you can download the Guide at bottom as well and print off (it is Microsoft Word format).

Yeah mate - I've printed that off and worn it out...but my speakers are horizontal - like this - and not like the majority of other speakers that sit like this l so my readings may be different...the array behind the grill cloth is completly different from "normal" speakers. They have 2 five inch woofers either end and in the middle are 2 21/2 tweeters on top of one another kind of like this 0 : 0 so the dispersion of the sound is totally different from other speakers that have the woofers stacked and maybe only one tweeter.

http://www.jamo.com/images/c/444/800x800.aspx

[rickardl]

Originally Posted by paulst10

Audyssey only uses the first position to set speaker levels, distance and obviously EQ, so you wouldn't need to take 8 different readings with the SPL metre as you are only 'checking' what Audyssey has done with regard to speaker levels (it's first reading) using the the amps internal tones

Yes, Audyssey uses the first position for trim settings BUT it uses
a spectral approach when doing that which is why suggested using
an average when doing it manually.
Not sure what you mean with that Audyssey uses the first position for EQ?
It uses all eigth positions when calculating the correction filters and the -3dB roll off point.
It is "room correction", not just "single point correction"...

[namuk]

Originally Posted by Basil Plumley

Yeah mate - I've printed that off and worn it out...but my speakers are horizontal - like this - and not like the majority of other speakers that sit like this l so my readings may be different...the array behind the grill cloth is completly different from "normal" speakers. They have 2 five inch woofers either end and in the middle are 2 21/2 tweeters on top of one another kind of like this 0 : 0 so the dispersion of the sound is totally different from other speakers that have the woofers stacked and maybe only one tweeter.

http://www.jamo.com/images/c/444/800x800.aspx

i no what you mean mate , laminating though is a good idea

I demoed them speakers Very good sound indeed , not sure why horizontal would make a difference this is new to me Basil, unless the Impedence 4 would make this change..

i must admit though you do need a new Spl like Paul said, 13 years is old news ones take Batterys

[paulst10]

Originally Posted by rickardl

Not sure what you mean with that Audyssey uses the first position for EQ?
:

Yes sorry, I meant 'as well as' the other positions over an averaged EQ, but didn't want to apply that in the same sentence implying that it sets speakers levels etc! upon the 'averaged' readings

[rickardl]

Originally Posted by paulst10

Yes sorry, I meant 'as well as' the other positions over an averaged EQ, but didn't want to apply that in the same sentence implying that it sets speakers levels etc! upon the 'averaged' readings

Aha ok.
Level and distance are kind of special since those has to be fixed to some
position which is why the recommendation is to use the centre of your
listening area. That might be the same as your main listening position
but then again, it might not. It just should be in the middle so all possible
positions get as accurate levels and delays as possible. Of course,
all 8 positions will not be in the sweet spot but the one furthest to the left
will be equally good/bad as the one which which is furthest to the right etc.

[Basil Plumley]

In a roundabout way, I posted the same question on the thread that namuk kindly linked to over on AVS - and the guys over there reckon it's best to trust the Audyssey and leave the levels as it sets them.
That was actually Mark from Onkyo's advice as well - this is particularly important if your AVR has Dynamic EQ (the 875 doesn't) as changing the levels will move the point of reference level from 0 on the volume dial - and when you use Dynamic EQ, it'll be looking for a reference point that's no longer there...

Even though I've found the answer to my question, it would be good for people with a knowledge of these things to post their opinions. I've kinda hit a brick wall in my studying of video calibration so will now turn my attentions to sound.

[24 P]

Don't forget your ears, they are an important tool to you know, if it sounds wrong, then possibly it is, make sure it sounds good to you regardless of settings...
Ultimately we are wanting the best, and if we need to deviate from a measurement done technically, the old ears can do wonders if 1 knows what they are doing..

[rickardl]

Originally Posted by Basil Plumley

In a roundabout way, I posted the same question on the thread that namuk kindly linked to over on AVS - and the guys over there reckon it's best to trust the Audyssey and leave the levels as it sets them.

yeah, I saw that but the poster who replied seemed to have forgot
that Audyssey does not set reference levels for the models with the
puck shaped mic.
That specific info about the lacking mic sensitivity I got directly from Prof. Chris Kyriakakis, Chief Technology Officer and co-founder of Audyssey.

[rickardl]

For later models with the newer Audyssey mic:
When you run MultEQ the trims are set to achieve film reference with the master volume at 0. At that point Dynamic EQ does nothing.
As you turn down from there it starts to apply compensation in the bass and in the surround levels to match human hearing changes.

But what if you manually change the trims afterwards?
There won't be any issue with changing the trims by an equal amount of dB.
In fact it does change the reference point when you do that.
You just have to know where on the volume control is "reference" because it will not be 0.
So, if you bump the trims with +2dB, you will have reference volume when your volume knob is at -2dB instead of 0dB.

[Pulse1]

Ok so you guys are saying that after calibrating with audyssey you can reset the speakers to small and reset the crossovers to say 80hz but you leave the speaker/subwoofer distances and levels where audyssey sets these ??

[namuk]

Originally Posted by Pulse1

Ok so you guys are saying that after calibrating with audyssey you can reset the speakers to small and reset the crossovers to say 80hz but you leave the speaker/subwoofer distances and levels where audyssey sets these ??

If your After Audyssey setup shows speakers at Fullband , yes you set speakers to Small/80Hz. Leave the rest