I like op amps, they certainly work better in my active crossovers than the series inductor in the passive ones I had before.
That said I find that there are fairly large differences between op amps, at least as much as in amplifiers. Those ancient TL072 and LF353 are horrible but I did replace them with OPA2134 and they are ok. Although there are better ones but they do cost a lot more than what I paid for the 2134s.
That said I find that there are fairly large differences between op amps, at least as much as in amplifiers. Those ancient TL072 and LF353 are horrible but I did replace them with OPA2134 and they are ok. Although there are better ones but they do cost a lot more than what I paid for the 2134s.
If 'EQ' provided by the speakers' crossover and the dispersion characteristics of the speaker design lead to smooth in-room frequency response, then I'd happily stay away from any other EQ. In reality, my two listening rooms could not be more different, and I'm sure they're acoustically quite different to most other friends' listening rooms. So as someone who until recently has studiously kept away from equalizers, when PC-based and digital EQ became practical, I was immediately attracted.
I don't seek to add or tweak the sound of my systems. What I basically aim for is consistent FR in different rooms, and most importantly, control of room modes that need room treatment that many would consider beyond normal WAF.
My current digital EQ, applied on a PC music server, does minimum phase FIR EQ for each room, based on measurements using a calibrated mic. Transparency has not been sacrificed. Reducing room problems has increased transparency, and it's must easier to hear differences between dacs, capacitor upgrades, etc. Soundstage is improved. Dynamic range is improved (fewer boomy notes). Really all I've done is re-jigged the speakers to match the room. If I could start afresh, I'd get speakers without passive crossovers, and only use digital crossovers, but strictly speaking it's still EQ. Applied in this way, I simply cannot understand why any 'purist' should pooh-pooh EQ.
I don't seek to add or tweak the sound of my systems. What I basically aim for is consistent FR in different rooms, and most importantly, control of room modes that need room treatment that many would consider beyond normal WAF.
My current digital EQ, applied on a PC music server, does minimum phase FIR EQ for each room, based on measurements using a calibrated mic. Transparency has not been sacrificed. Reducing room problems has increased transparency, and it's must easier to hear differences between dacs, capacitor upgrades, etc. Soundstage is improved. Dynamic range is improved (fewer boomy notes). Really all I've done is re-jigged the speakers to match the room. If I could start afresh, I'd get speakers without passive crossovers, and only use digital crossovers, but strictly speaking it's still EQ. Applied in this way, I simply cannot understand why any 'purist' should pooh-pooh EQ.
audio frequency L are the technically poorest performing class of passive component - sorta like being stuck with using only bad electrolytic capacitors, but worse
op amp RC filter circuits are used not just to avoid large, expensive inductors but because they can perform measurably better as well
op amp RC filter circuits are used not just to avoid large, expensive inductors but because they can perform measurably better as well
Yes.. opamps measure well (these are differential amps using loads of feedback) but can these sound as good as a SE discrete amps without global NFB ?
IMO NFB produces compression on the higher frequencies and blurs the lower frequencies... Of course an amp made around good opamps can measure much better than a SE dicrete one but it does not breathe as well. It lacks speed.
IMO NFB produces compression on the higher frequencies and blurs the lower frequencies... Of course an amp made around good opamps can measure much better than a SE dicrete one but it does not breathe as well. It lacks speed.
The prime culprit of blurring bass is the usual series inductor in passive xovers.
Consequently tight, clean bass is the main improvement of active ones.
I have never heard a passive speaker get anywhere near the clean bass actives provide, regardless of preceding amplification. Since I swapped the TL072s in mine for OPA2134 the treble is also smoother, cleaner, more open and more real sounding than with the passives I had.
In fact of all the tweaks I have tried during my 30 years fiddling with stereos nothing provided as much of an improvement as going active.
Consequently tight, clean bass is the main improvement of active ones.
I have never heard a passive speaker get anywhere near the clean bass actives provide, regardless of preceding amplification. Since I swapped the TL072s in mine for OPA2134 the treble is also smoother, cleaner, more open and more real sounding than with the passives I had.
In fact of all the tweaks I have tried during my 30 years fiddling with stereos nothing provided as much of an improvement as going active.
We are talking different matters here.... Of course active speakers work much better than passive ones with complex energy wasting crossovers.
In an active speaker we can have dedicated amps for each driver, operating in ideal frequencies / conditions.
I was just claiming that a simple (non active) system sounds better if implemented with discrete parts (with low parts count), avoiding diferential amps and opamps.
NFB is no good for music flow.... It is good if you want to implement a commercial product that measures well enough to be compared in Stereophile mag.
In an active speaker we can have dedicated amps for each driver, operating in ideal frequencies / conditions.
I was just claiming that a simple (non active) system sounds better if implemented with discrete parts (with low parts count), avoiding diferential amps and opamps.
NFB is no good for music flow.... It is good if you want to implement a commercial product that measures well enough to be compared in Stereophile mag.
The low pass in my old passives was as simple as it gets: A single series inductor and a parallel cap. Nothing else.
This I replaced with a rather complex active one which features limiters, 180deg adjustable phase between channels, phase inversion, level adjustment etc.
Each contains an eye watering 25 op amps although I don't think I am using all at the same time as they are switchable between stereo 2way or mono 3-4way. I use two as 4way monos.
Yet the improvement, even with the original lowly TL072, was very impressive.
The amps I use are MC2 Audio class a/b pro amps although one is badged Tannoy and another Quested Audio.
Anyway by the time a musical signal ends up on a cd, file or a slab of vinyl it has already been through dozens if not hundreds of op amp.
Oddly enough some of the most highly regarded and costly analogue consoles Neve are cramped full of thousands of TL072s. Personally I am not the greatest fan as they are coloured (its that colour that so many love), I prefer the cleanliness of SSL consoles at that market segment.
Lastly I have no opinion on negative feedback as I neither design nor build amps. I do however care about the result and how it compares to the live instrument.
This I replaced with a rather complex active one which features limiters, 180deg adjustable phase between channels, phase inversion, level adjustment etc.
Each contains an eye watering 25 op amps although I don't think I am using all at the same time as they are switchable between stereo 2way or mono 3-4way. I use two as 4way monos.
Yet the improvement, even with the original lowly TL072, was very impressive.
The amps I use are MC2 Audio class a/b pro amps although one is badged Tannoy and another Quested Audio.
Anyway by the time a musical signal ends up on a cd, file or a slab of vinyl it has already been through dozens if not hundreds of op amp.
Oddly enough some of the most highly regarded and costly analogue consoles Neve are cramped full of thousands of TL072s. Personally I am not the greatest fan as they are coloured (its that colour that so many love), I prefer the cleanliness of SSL consoles at that market segment.
Lastly I have no opinion on negative feedback as I neither design nor build amps. I do however care about the result and how it compares to the live instrument.
THANKS GOD...ALL AMPS SINCE 60'S BEFORE AND TODAY HAVE T CONTROLS , SOME COULD BE SKIPPED BPSING, BUT RARE EQ WITH BANDS SUCH AS MIDS , BUT 2 SCREWS BASS/ TRBBLE HAHAGo digital, my friend. Go digital.
For Ams-Neve no models i know (V series/88R mainly) are using TL072 in signal path. Mainly 5534/5532 as in the SSL Series 4000 G/E and 9000 Series. Older Neve design are mainly discrete designs. Most of the colour of Neve's desk (and Ams-Neve) comes from mic input transformers and in some older design from the output transformers.
Sorry for the slightly off topic comment...
It depends. Some hi end results are possible with passive xo ... but at an inaffordable price!
Anyway i must admit going active is the next step i'm going to take for my own system. And probably going digital for filtering/delay compensation.
Anyone who doesn't have tone controls is a sucker. Having said that, some tone controls are poorly designed or are too limited in what they can try to do. I prefer a four section baxandall or actually the passive version called the James. This gives me good control on whatever variation of reverse Fletcher-Munson (Loudness Comp) might work best for my ears and my room acoustics. It also is a pretty flexible approach to dealing with poorly EQ'd recordings of great music that pop up now and then. I use tubes largely for their increased headroom and lack of phase margin issues since no feedback is used in the James version.
So many people don't realize the degree to which listening room acoustics (and recording environment acoustics, and mic techniques) screw up what you eventually get at your ears. They also don't realize that certain room acoustics problems can be made more apparent with tone controls, and it's not the tone controls fault. If the placement of the woofers and/or lower midrange drivers are in a bad location acoustically, relative to both room boundaries and listener position, thereby causing significant un-eveness in the lower frequencies, then bass will sound boomy. Turning the bass up will only make that more dominant.
Another thread at this website has over 175 pages of people discussing the question: Is flat what we want?". Every one of the people said flat sounded too harsh, brassy, cold and thin, in a variety of different ways. Tone controls are great if the room acoustics situation is properly dealt with first. This is why I'm a huge fan of the satalite/subwoofer approach. You set up the 100HZ and up speakers where you want the soundstage to be, and then you put the woofers where they interact with room boundries and listening position the best. Substantial improvements can usually be made with this flexibility. The wavelengths of lower mid and bass frequencies are such that you are hard pressed to tell exactly where the sound is coming from anyway. It's generally the higher frequency harmonics of the bass notes that give you the localization cues. I found that adding a center channel speaker that goes down to at least 70HZ helps fill in cancellations caused by reflective surfaces and room boundaries (walls and major furniture pieces), since it's in a significantly different physical location in the room than the left and right speakers.
If you look at high end preamps, you find that most between $5000 and $150K do not have tone controls at all. What a joke the audio market has turned into. And $500 interconnect cables?! It goes on and on.
Graphic or parametric EQ's are another thing. While very useful for those who know how to use them properly, many people who have such devices don't really have a clue. You have to understand acoustics and comb filter effects due to reflections. Resonance build up and decay times and their psycho-acoustic effects. The concept that you can't force an acoustic cancellation back up in amplitude electronically without creating other often worse problems, etc. Acoustics are complex and often very damaging. Without understanding that, you could easily throw the blame on the tone controls. Good tone controls are an absolute MUST.. No reproduction chain is good enough without them when you consider all the variables. My system sounds MUCH better with significant tone adjustment (4 band Baxandall (variable slope) right now). Quad and Luxman (and probably some others) had a "tilt" switch that tilted the whole response from about 200HZ to 10kHZ down about 3-5 dB. It was apparently a big hit. That's largely what my tone controls are doing right now.
So many people don't realize the degree to which listening room acoustics (and recording environment acoustics, and mic techniques) screw up what you eventually get at your ears. They also don't realize that certain room acoustics problems can be made more apparent with tone controls, and it's not the tone controls fault. If the placement of the woofers and/or lower midrange drivers are in a bad location acoustically, relative to both room boundaries and listener position, thereby causing significant un-eveness in the lower frequencies, then bass will sound boomy. Turning the bass up will only make that more dominant.
Another thread at this website has over 175 pages of people discussing the question: Is flat what we want?". Every one of the people said flat sounded too harsh, brassy, cold and thin, in a variety of different ways. Tone controls are great if the room acoustics situation is properly dealt with first. This is why I'm a huge fan of the satalite/subwoofer approach. You set up the 100HZ and up speakers where you want the soundstage to be, and then you put the woofers where they interact with room boundries and listening position the best. Substantial improvements can usually be made with this flexibility. The wavelengths of lower mid and bass frequencies are such that you are hard pressed to tell exactly where the sound is coming from anyway. It's generally the higher frequency harmonics of the bass notes that give you the localization cues. I found that adding a center channel speaker that goes down to at least 70HZ helps fill in cancellations caused by reflective surfaces and room boundaries (walls and major furniture pieces), since it's in a significantly different physical location in the room than the left and right speakers.
If you look at high end preamps, you find that most between $5000 and $150K do not have tone controls at all. What a joke the audio market has turned into. And $500 interconnect cables?! It goes on and on.
Graphic or parametric EQ's are another thing. While very useful for those who know how to use them properly, many people who have such devices don't really have a clue. You have to understand acoustics and comb filter effects due to reflections. Resonance build up and decay times and their psycho-acoustic effects. The concept that you can't force an acoustic cancellation back up in amplitude electronically without creating other often worse problems, etc. Acoustics are complex and often very damaging. Without understanding that, you could easily throw the blame on the tone controls. Good tone controls are an absolute MUST.. No reproduction chain is good enough without them when you consider all the variables. My system sounds MUCH better with significant tone adjustment (4 band Baxandall (variable slope) right now). Quad and Luxman (and probably some others) had a "tilt" switch that tilted the whole response from about 200HZ to 10kHZ down about 3-5 dB. It was apparently a big hit. That's largely what my tone controls are doing right now.
when i did pro installations for concert halls etc. (over 20 years ago) we always used eq's and calibrated measuring equipment to compensate for the room. It was a night and day experience.
tone controls and EQ are not the same thing (at least not how i was taught this when i did this professionally). we used very wide spectrum eq's to calibrate the room with the system, but we also had tone controls on the console for the person doing the mixing. This was separate and used to change the sound, while the EQ solved a different purpose eg correcting the room. the monitors in the mixing room as well as headphones tapped in before the eq and the amp stack. Any recording was done pre the eq.
now that its affordable to measure the room and the system in one i am going back to using equalizing techniques again, the affordable digital technologies such as minidsp seems to be the way to go.
tone controls and EQ are not the same thing (at least not how i was taught this when i did this professionally). we used very wide spectrum eq's to calibrate the room with the system, but we also had tone controls on the console for the person doing the mixing. This was separate and used to change the sound, while the EQ solved a different purpose eg correcting the room. the monitors in the mixing room as well as headphones tapped in before the eq and the amp stack. Any recording was done pre the eq.
now that its affordable to measure the room and the system in one i am going back to using equalizing techniques again, the affordable digital technologies such as minidsp seems to be the way to go.
I do speakers and I know for sure one thing: you always need to compensate for stuff like rising impedances, break up modes, driver behaviour, efficiency, diffraction effects, and the list goes on. In other words, there is not one good speaker that does not equalize one thing or another, and many of these corrections have phase effects.
Therefore, I see no fundamental reason not to use equalization further up in the chain, to deal with acoustic anomalies outside the box. That is, the room you put these speakers in to listen to them.
Therefore, I see no fundamental reason not to use equalization further up in the chain, to deal with acoustic anomalies outside the box. That is, the room you put these speakers in to listen to them.
IMO Room/Speaker EQ should be done as much as possible with room treatment. In many cases this can eliminate the need for electronic/software based EQ. However Tone controls are still needed even in a 'perfect' room, to correct issues in recordings. Too bad it is so hard to correct the compression so prevalent in recordings.