Improving Bass Control

Huge posted:

George Fredrik Fiske posted:

The bottom octave on most pianos is fairly toxic! The bottom note almost always so!

ATB from George

Dear George, as a chemist and a biologist I do find the idea of toxic notes to be an interesting concept.  

Expressed of course as LD50 aural, in dB/Hz...

I think you know what I mean quite well! Another bass instrument with a notoriously sour tone in its lowest notes is the Contra-bassoon - sometimes called the Double-bassoon.

The good ones are outnumbered by the horrible ones!

ATB from George

Also shouldn't forget the phenomenon described by Seebeck in 1841 that pitch is perceived more strongly in complex tones rather than simple tones, and later in a paper published in 1962  by J. F. Schouten et al "Pitch of the Residue" based on Seebback's phenomenon showed we don't need to hear the fundamental to perceive bass... so we can detect and experience pitch where physically it doesn't exist in a replay system. There is a much interest  in developing this understanding further currently in terms of implementation  because of the preference for smaller and smaller replay speakers in devices. Again the AES has an open access article (free to read) called Bass Enhancement Settings in Portable Devices Based on Music Genre Recognition by Hoffman and Kostek exploring this further - looking at how pitch is perceived and how to trigger responses in our brain with DSP

The science of audio replay systems and psycho acoustics is fascinating... 

Simon

...possibly the only manufacturer that can execute a piano that reproduces the lowest fundamental notes (certainly not Steinway IMHO), regardless of the extra keys.

If the eu gets to hear about this they'll make a law banning the bottom notes of instruments. sTeinwai will have to cut out a section of the bottam A string so that it won't sound, Contra Bassoonists will have to drill an extra hole so they cant stop them all, and as for big organs....best go no further.

Just because there are so many over-weight organs does not mean that all organs are horrible in the bass department:

https://www.youtube.com/watch?v=OKrZPrMYmOo

One of my favourite Bach Chorale Preludes on a very recent recording, by a lovely musician organist.

And the ESL gets it all in good proportion in spite of the legend that the speaker type cannot do deep bass!

Bass should be articulate, clear of pitch and in good balance with the other voices ... And the icing on the cake with the ESL is good timbre as well ...

Not thunderous for the sake of it!

ATB from George

And here is a wonderfully life enhancing fugue. The Gigue Fugue ... Shows how an organ at its best can be made to sound. Everything clear, and full of energy and momentum!

https://www.youtube.com/watch?v=yz2TmvVhO_8

ATB from George

sheffieldgraham posted:

My room is quite small with a wood suspended floor. 

 

 Speaker position leads to very big improvements in bass response. Otherwise if nothing works try room treatment. 

Using an on line room node calculator (be precise with your measurements) to find out where you room nodes are, frequency wise.

Use a sound level app on your phone with the mic exactly at ear position. This will not be accurate, but its useful for relative (ie changes in) measurements.  Download tones frrom 20 to 150 Hz and play each one, noting the readings at each frequency. Play the tones quite loud ( about 9 or 10 o'clock on a Naim pre amp) don't touch the volume control after that.

You will see humps and troughs. Move your speakers in the room and repeat, you will see the relative changes in the peaks and troughs. Maybe try stuffing duvets into corners of the room and measure again.  It will help you get the best out of what you have and give you clues about room treatment.

You could buy a streamer or a processor that could notch the under 100Hz frequencies to null the room nodes. This and the room/speaker interface sorted out will be more fundamental than changing amps, racks etc.

I answer to the OP - my most recent upgrade was from a single NAP250 to a pair of NAP135's.  Perhaps others can explain the full difference in design and output from these two power amps but the audible improvement in bass control is quite remarkable - much less boom (in what is probably not the easiest room) deeper bass, better "agility" from one note to the next on stringed bass, for example.  It's a bit of a hifi cliche - but I really am hearing new details being played on recordings I've owned for more than 30 years.  

sunbeamgls posted:

Using an on line room node calculator (be precise with your measurements) to find out where you room nodes are, frequency wise.

Use a sound level app on your phone with the mic exactly at ear position. This will not be accurate, but its useful for relative (ie changes in) measurements.  Download tones frrom 20 to 150 Hz and play each one, noting the readings at each frequency. Play the tones quite loud ( about 9 or 10 o'clock on a Naim pre amp) don't touch the volume control after that.

You will see humps and troughs. Move your speakers in the room and repeat, you will see the relative changes in the peaks and troughs. Maybe try stuffing duvets into corners of the room and measure again.  It will help you get the best out of what you have and give you clues about room treatment.

You could buy a streamer or a processor that could notch the under 100Hz frequencies to null the room nodes. This and the room/speaker interface sorted out will be more fundamental than changing amps, racks etc.

This is a good idea for an initial investigation, but I would suggest two modifications

First use a Spectrum Analyser app on your 'phone (or tablet)

Second rather than spot tones, download a frequency sweep track to play as room resonances can have quite high Q vaues and hence have very narrow peaks.  You may miss them using spot tones.

Compare the peaks to the general trend of the spectrum, NOT to a straight line.  The microphone in 'phones often has a response that falls off quite quickly below 80-120Hz, you need to compare the peaks to the trend line of the troughs to really see where the peaks are.

If you find you have significant resonances, then you can measure them accurately using a miniDSP UMIK-1 microphone (~£80) and a copy of REW.

If you use speakers with limited bass extension that don't excite the room resonances too much (you can always put bungs in ports!)  but still want good bass; you can use a miniDSP 2x4 to control a sub, using the DSP to reduce the drive level at the room resonances so achieving a much better quality of bass as well as bass extension.

I have just caught up on this great discussion, through which I slept in my time zone around the planet.

How low must the bass reproduction reach?  Many posts mention the lowest sustained notes of various acoustic musical instruments.  But, of course any transient sound - percussion instruments come to mind - contains "broad band energy," not just a fundamental tone plus harmonics.  So having a lower limit on bass reproduction has the potential for a more convincing sound of the attack on transients of almost all instruments (or for less convincing if not well done).  Few domestic systems can convincingly approach the sound of a pipe organ or a marching band, of course, so as listeners we adopt a "suspension of disbelief."

Charlie

Huge, your system is actually very expensive if you count your labor - all those costly consulting fees.

joerand, you are right that a room and loudspeaker(s) form a "system" from the acoustical point of view.  And when we make measurements, we most commonly are measuring this complete loudspeaker + room system.  This is where things get interesting for the designer of loudspeakers or domestic hifi systems!  We must take into account the "psyco-acoustic" perceptions of a "listener."  As listeners, we are actively listening for the music, and relating the "raw" sounds we hear (which are the same sounds one might measure with a pair of proper microphones) and then processing those sounds in our brain to distill to what we "percieve."  The result is that we percieve a "sound stage" and some recognizable voices or instruments playing in our room, perhaps awash with reverberant sound.  This processing we perform can have the effect of somewhat separating the room from the loudspeakers.  This is discussed at length by Floyd Toole in his book and many papers.  Simon must be familiar with much of this literature, more than I?

So someday perhaps we will learn how to add this human-perceptual signal processing to our measurement systems, and this will be a great addition to the toolset of the acoustical engineer.

Charlie

CharlieP posted:

Huge, your system is actually very expensive if you count your labor - all those costly consulting fees.
...

Charlie

Unfortunately I don't think you can count the consultancy fees.  The client is a real skinflint and has refused to pay ; he even refused to pay for the physical work done - the only thing he actually paid for was the materials.  Even if I took him to court I'd still be out of pocket.  Best just write off the fees!  

I have had bass boom issues in my room with SL2's, Proacs (on demo) and with my current S600's. I have posted on the granite under speaker thread of the attempts I made to correct this, Room treatment, digital room correction, granite under speakers and speaker placement, none of these worked apart from digital correction which had the side effect of making the system bass light.

I believed the problem was related to speaker/room issues, but I am now free of the bass boom, due to isolation of speakers and racks from the floor and also upgrading (recently serviced 300's) with the DR versions.

So in answer to the OP I would say  power amp,  isolation and room speaker interaction which I experienced in my previous house. It should be noted that the problem was present with a 552 DR in the system, so in my experience the pre-amp had little impact on bass control.

GerryMcG,

Sometimes isolation, if done properly (linear and the appropriate corner frequency) can sound "better" than coupling (or perhaps it is more achievable?).  It is good that it is working for you and you are satisfied with how your music sounds.  Paul Messenger spoke very highly of speaker isolation, as I recall.  You are right that the mechanical loudspeaker - floor interface is important on the list for bass control.

Charlie