2. amps-preamps
  3. 1253341271

Is this clipping or just high SPL?

Hey everyone,

A question arose today during a listening session. I have a Yamaha M40 120wpc amp driving GMA C1's with a passive pre-amp. I usually run both my pre-amp and amp at about 12... but on rare occasions I will turn my pre-amp up all the way and boost my amp to about 2 or 3 o'clock. I do this on recordings that seem to be mastered lower than usual...

Anyways, today I was listening at the higher play levels and a particularly abrupt loud passage came... specifically, it was 'Dark Side of the Moon' when the bells come in on the beginning of the third track (that everyone has heard at least 40 times).

I didn't hear any clipping, and never have on this system... but things just sounded more congested with less separation and clarity than I'm used to. Given, it only lasted about 10 seconds during that one sequence... but it sparked the question of whether it was likely that the amp was clipping or that it was just loud beyond my comfortable listening level. I am in a small room about 8 feet from the speakers, btw...

Thanks.
djembeplay
rodman99999
6,206 posts
 
DJ- To answer your question: YES, reflected sound/loud mush at the listening position. As an experiment: find two or three large, thick comforters and drape them on the wall, behind your listening position. That should let you know if slap echo is the problem. Of course- it's also possible that the side walls can contribute as well, but the front and back walls are generally the main offenders.
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
As Linkwitz states, in the article I referred to,"the large low frequency voice coil displacements can cause large amounts of intermodulation distortion products near the high frequency signal due to the large low frequency variation of Le(x)."

A bell or chime is percussive and contains loads of low AND high frequencies all at once - just like a Cymbal...so it is a tough to impossible test for most speakers to generate at high SPL levels without some audible distortion or congestion...
djembeplay OP
179 posts
 
Gotcha - thanks guys.

I just listened again at a slightly lower volume and worked my way back up... because this was driving me nuts.

It sounds fine, actually... I think I'm just not used to playing at higher SPL's than what I'm used to... in fact I'm really impressed with these old Yamaha amps. I think what I was hearing was a combination of room reflection and having sensitive ears... (which seems to vary from day to day for me... some days loud sounds are less tolerable than others... anyone else experience this?).

Incidentally, I would like to measure the DB to get a sense of proportion.

Out of curiosity, if a speaker does have some audible distortion / congestion in a loud passage, but not to the point of obvious clipping... is this going to damage a speaker or just be annoying? Will high end speakers on high end amps all pretty much start to congest at these 100-105 DB ranges?

I doubt I'm up that high in this small room... I hope.
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
Will high end speakers on high end amps all pretty much start to congest at these 100-105 DB ranges?

At 2 meters from the speaker - yes absolutely. Soundstage will not even test speakers at 100 db SPL as most would get damaged - see quote below from soundstage:

As volume increases, all frequencies should rise at the same rate. However, as a speaker is stressed, compression will occur at certain frequencies. The stress may be mechanical, thermal or otherwise. This test shows those frequencies at which deviation occurs as a result of compression. Many speakers show slight deviations at 90dB. Most speakers start to show serious deviations at 95dB. Very few speakers can be tested at 100dB without damage.

Furthermore remember that soundstage are NOT making IMD tests - so their results look artificially good (when a speaker plays simultaneously high and low frequencies you get MORE distortion).
djembeplay OP
179 posts
 
Thanks for the info Shadorne.

I guess I would need to test my DB to get a sense of where I'm at. There are DB charts with examples scattered about, but I'm not sure how the loudness of these compares to that of a lawnmower from 3 feet away or that of a jet engine at take-off.

The higher levels that I have been referring to are powerful with impact yet still comfortable and clear from only 8 feet away on DSOTM (as long as we are referring to this album I might as well stick with it). I consider myself to have fairly sensitive hearing... sooo chances are I'm not into the 90DB death range... right?
More to discover