The room and speakers “process the signal”. Well engineered room correction is designed to counteract this within the limits of physics and audibility so that the end result is closer to the “signal”.
No. Please try to follow this and agree - or disagree if you think I'm wrong! I’d be interested to learn where you disagree.
1. The "signal" starts with your source not the speakers - streaming service, CD, vinyl, etc - do you not agree?
1. The signal goes (often via a DAC) to the amp. The best ("straight line") amps simply amplify this signal - nothing else - this keeps it as pure as possible - no tone controls or other processing - do you not agree?
2. This amplified signal reaches the speakers that (if of excellent quality) will accurately convert the electronic signal into movement of air (sound) within your room - How are we doing so far - I hope you agree
3. Then this moving air that carries the sound is subjected to certain reflections and other undesirable features within your room. The upper frequencies are much less affected by room anomalies than lower ones - agreed?
4. If your speakers are very good and if they are well set up and if your room is carefully carpeted and furnished (usually without the need for ugly treatment panels, etc), the sound should still be excellent, but may still have some variation in lower frequency levels - I accept this and no doubt you do to
5. OK, if you've failed at the crucial Stage 4 measures (choice of speaker, setting up speakers, room furnishing). then you may think a little electronic room correction is needed. There are 2 distinct ways of doing this. Either:
A. within the amplifier, in which case this nice pure signal at Stage 2. is subjected to an additional stage of electronic processing before being passed to the speakers. Sadly this requires the entire frequency range to suffer from this extra stage of processing, although it's really only the bass that your room tends to spoil. Or:
B. within the speakers after the crossover. This can only be achieved with active speakers or subs or perhaps if you use an electronic crossover and have 2 or 3 amps for the various drivers (post-XO bi- or tri-amping). If you have this type of setup, then DSP can be applied only to the bass and not to the sensitive upper frequencies that provide the liveliness and sparkle to your music and are much less affected by your room's acoustic peculiarities.
Speakers such as Avantgarde XD, Martin Logan Masterpiece, Dutch & Dutch, etc have this ability to forward the upper frequencies unmolested by DSP processing to the top drivers, but do apply DSP to the bass by processing within their dedicated bass amplifiers.
I currently have Dirac Live but used to have RoomPerfect and MARS DSP systems built into amps and all do adversely affect the top frequencies that contribute to liveliness and excitement factor, even though some of these DSPs only adjust the lower frequencies (Dirac is sub 500 Hz). Unfortunately the “signal” at this stage covers the entire frequency range so all frequencies endure this processing.
I’ve carefully selected my speakers for my own room, taken time and trouble to set then up as best I can and (since buying an empty echo chamber of a new-build) have furnished my room with a nod to the speakers’ requirements. I’ve achieved a degree of audio performance where I notice that the sound is more lively and exciting to listen to without this DSP filter in the amp. It takes money, time and effort but it’s well worth persevering with Stage 4. above to achieve this sound.
In fact, I’ve found that some TYPES of speaker fare poorly in my room, I had to sell my costly electrostatic panels (Martin Logan 13As) last year and start again. They were disappointing because of their placement in my room that I could do nothing about. This poor sound could not be resolved even by their own built-in Anthem DSP and I now fully understand the reason for this problem in my own room and why panels just won’t work here. A costly lesson - always arrange a home demo.
An interesting aside – If DSP was as good as some people believe it to be, what’s the benefit to speaker designers of doing anything more than plonking 3 drivers (with XO) into a cabinet and leave DSP to make them sound fantastic? DSP cannot make a silk purse out of a sow’s ear. Best to start with silk and ensure the stitching is carefully done to make your purse!