One man's opinion, No. If you build the ESP crossover he recommends several different options including NE5532 and OPA2134 and says any dual 8 -pin op amp will work but I would be careful as sometimes "super fast" op amps can oscillate and the recommended ones are readily available, cheap, and work well. Good luck and have fun in any case.
-
WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
Active crossover types
- Thread starter dennnic
- Start date
Another man's opinion:- The NE5532 is quite good enough to work at line level, and unity gain in an active crossover. The OPA2134 is quieter, and may be an improvement if the drivers you're using are very sensitive, especially the midrange driver in a three way.
As to discrete opamps, they used to be a bit quieter, but that's not the case any more, so I can't think of any good reason to use them. They're also a lot more expensive, take up more room on a pcb, and may not be a compatible replacement for all opamps, especially if they're used at unity gain.
S
No. Every music you hear has already passed through hundreds of op amps before it reached your ears.
There are both analog and digital crossovers available in the pro music shops, by e.g. Behringer (CX and Ultradrive series) and DBX (Driverack series). Maybe easier to handle. The analog versions of course do not offer much in terms of flexibility or additional EQs.
No, just the opposite. Most discrete opamps measure worse compared to the best chip opamps. There is a reason why all transistors are on one chip.
Active Crossovers, Amplifiers and Bi-Amplifiers
Bi-Amping is the replacement of your speaker’s passive crossover with a precise Active Crossover. The result is breathtaking. You’ll hear detail in your music you’ve never heard before.
After you get the crossover sorted out you can get rid of the full range driver and get proper mid ranges and tweeters.
Yes, I am on this direction. For OP @dennnic's reference, you may find my present multichannel multi-driver multi-way multi-amplifier stereo setup in my post here. The system configuration can be summarized in these four diagrams;
Please visit my project thread for the details.
Last edited:
- Thread Starter
- #28
Strange, considering all the market hype on some sparko discrete op amps.
How would you comment the usage of tubes for the same application??
Marchandler offers two versions of tube active crossovers in their lineup. Almost three times the price to replace an OPamp with a tube. Is there anything to be gained by going that way?
Hype is the correct word when it comes to discrete op amps. It is sad and difficult for many audiophiles to accept that technology moves ahead and that magic "hand made discrete circuits" can not outperform cheap and easy mass produced op amps. The reality is mass produced op amp do outperform discrete and the reason is that there is a tremendous amount of engineering that goes into these op amps that get spread over millions or parts so they are both well engineered and inexpensive. The opposite goes for discrete op amps.
If you search these boards about "tube sound" you will see that it is a perpetual argument and there is not even a consensus if there is such a thing. Since this is an objectivist science based forum most will point out that tubes are higher distortion, higher noise, more expensive and more dangerous. Some will claim "sound better" with no objective data and so it goes.
My experience is that tubes circuits are fun and if carefully engineered will come close to the performance of op amps but it will come at a much higher cost, lower reliability, and really a lot of effort to try to keep the noise down. Practically speaking tubes make no sense and well engineered tube circuits will be indistinguishable from a well engineered SS circuits. If a tube circuit does sound different it is because it is broken and is adding noise or distortion. If you really want to try tube distortion you can buy a "tube buffer" for that purpose. For me I see no sense in baking distortion and noise into an active crossover.
I couldn't have said it better!
- Thread Starter
- #31
I'm quite acquainted with tubes and their sound. A product of harmonic distortion, that's not actually there etc...
With all that aside, I was asking strictly from a technical standpoint - would a tube be a good replacement for an OPamp?
From a strictly technical standpoint, tubes are not even close. Some of the reasons I quit using tubes in the nineteen seventies were that
Tube are much more mortal than solid state devices. The electron emitters have a finite life. So leaving them on all the time shortens the time you have to use them. As they age you don't know the effect on the circuitry.
They are hot , and have bad effects from thermal cycling such as internal movement that can change characteristics or even cause shorts between elements. (Tube testers test for shorts). Also nature literally abhors a vacuum. Even if the glassblowing is perfect (which it sometimes is not) atmospheric hydrogen can diffuse through anything even metal and cause gassiness (especially in vintage New Old Stock tubes) It was said that the Russians continued to use them in avionics because they may be more resistant to electromagnetic pulses than solid state gear. However if there is a nucular exchange I don't think I am going to be listening to my stereo. (I had a pair of Mac MC75 power amps which I sold when good matched pairs of KT88 tubes started becoming difficult to obtain. About a year later MacIntosh stopped replacing tubes for free at their Mac clinics, which they used to do. This was about the time that good complementary pairs of power transistors became available. The days of tubes were over. Until their renaissance started much much later)
I also am of the opinion (yes it's an opinion) that all the engineers who ran the tube manufacturing facilities and understood vacuum tubes down to their bones, are all gone now. Also all the great WWII vintage design engineers who grew up using tubes. The engineers involved in most stuff are just trying to build something that will sell to people who wrongly think there is something worthwhile about tubes. There is nothing. When I see an umpteen thousand dollar McIntintosh 75wpc tube amp with green LEDs under the tubes I just shake my head.
It is very doubtful that anyone could pick out one decently selected op amp in an ABX test. But it does not take an audio precision analyzer to rate op amp chips.
I wonder if you could clarify for me. Why is it OK to use a woofer with your "full range" (mostly a contradiction in terms) but not tweeters.
I find "full range" speakers to usually be an audiophile myth of the type we don't tolerate too well here. The laws of acoustic physics and engineering don't change just because you bought a Lowther or a Voxativ driver or one of the other ones. They need a small tweeter as much as they need that big wooofer.
Tube are much more mortal than solid state devices. The electron emitters have a finite life. So leaving them on all the time shortens the time you have to use them. As they age you don't know the effect on the circuitry.
They are hot , and have bad effects from thermal cycling such as internal movement that can change characteristics or even cause shorts between elements. (Tube testers test for shorts). Also nature literally abhors a vacuum. Even if the glassblowing is perfect (which it sometimes is not) atmospheric hydrogen can diffuse through anything even metal and cause gassiness (especially in vintage New Old Stock tubes) It was said that the Russians continued to use them in avionics because they may be more resistant to electromagnetic pulses than solid state gear. However if there is a nucular exchange I don't think I am going to be listening to my stereo. (I had a pair of Mac MC75 power amps which I sold when good matched pairs of KT88 tubes started becoming difficult to obtain. About a year later MacIntosh stopped replacing tubes for free at their Mac clinics, which they used to do. This was about the time that good complementary pairs of power transistors became available. The days of tubes were over. Until their renaissance started much much later)
I also am of the opinion (yes it's an opinion) that all the engineers who ran the tube manufacturing facilities and understood vacuum tubes down to their bones, are all gone now. Also all the great WWII vintage design engineers who grew up using tubes. The engineers involved in most stuff are just trying to build something that will sell to people who wrongly think there is something worthwhile about tubes. There is nothing. When I see an umpteen thousand dollar McIntintosh 75wpc tube amp with green LEDs under the tubes I just shake my head.
It is very doubtful that anyone could pick out one decently selected op amp in an ABX test. But it does not take an audio precision analyzer to rate op amp chips.
I wonder if you could clarify for me. Why is it OK to use a woofer with your "full range" (mostly a contradiction in terms) but not tweeters.
I find "full range" speakers to usually be an audiophile myth of the type we don't tolerate too well here. The laws of acoustic physics and engineering don't change just because you bought a Lowther or a Voxativ driver or one of the other ones. They need a small tweeter as much as they need that big wooofer.
Last edited:
- Thread Starter
- #33
I see that that full range really bothers you. It was a compromise, before everything else. The goal was to create a point source, phase coherent... As it can't be done, the closest thing would be an extended midrange driver, accompanied by lower and higher frequency driver's support. Big woofers are easy to integrate and open baffle application really needs additional cone area as frequency goes down.
On the other hand, I had a tough time figuring out the tweeter, in order to optain an uniform vertical off axis response. I think the best solution would be a coaxial midrange-tweeter driver. Another problem in this part of the world is obtaining the parts. So I opted for the smallest full range (4 inch) I could find localy made and 12 inch woofers from the same company. I gave some thoughts on RAAL dipole ribbons, they are locally made over here as well, but it gets expensive very fast and it needs another crossover to the midrange. As you can see, I'm not the best at doing crossover work, especially passive ones. Plus it seems too complicated and overly expensive for the first project.
Thanks for your input, I think I'll just stick with chip op amps and tried and tested design from sound-au.com
Last edited:
A tube would be lower performance, much higher cost, and much lower reliability so no they would not be a good replacement for an op amp.
Killingbeans
Major Contributor
Listen and choose the 8th generation digital copy.
Each of these zip files will open into three wav files. One is labeled Reference, one is A and one is B. These are 30 second snippets of full songs. The originals were from CD so all 44.1 khz and 16 bit. Either A or B has been thru 8 generations of DA to AD copying. The other is identical...
www.audiosciencereview.com
Keep in mind that every time those samples was converted back and forth, the analog signal probably also went through several op-amps.
Last edited:
That's quite clear, thank you.
What is not clear is why, with 4 discrete output channels from the NanoDigi unit, two DAC are required. If the conversion takes place *prior to the crossover function* the output of the unit can be fed directly to the amp dedicated to each driver, if the amplifier has SPDIF inputs.
The inference I make is that the OP is keen to retain a set of existing amplifiers, when contemporary amps with SPDIF inputs are commonly available.
If a lower "box count" is desirable, fewer low level signal processors would be my choice.
- Thread Starter
- #37
It makes it simle then, I'm gonna start with Rod's PCB, it's by far the most affordable option too.
He recommends power supply of 15V (one of his projects). I wonder, what determines the voltage specification of a circuitry?
I have a Teddy Pardo PSU (as a Naim upgrade), that has one 18V output unused. If I opt for an OPamp that supports such a high voltage, would I be able to use it?
BB (TI) opa 2134 claims up to 36 volts and it's reasonable priced.
Nano Digi outputs digital signals only and therefore, if you want to use it's crossover function, you have to convert both signals for a 2way system. It does not have any AD converters inside.
If you are ordering the crossover boards from Rod you should look at his P05 power supply. It is +/- 15 volts and has some other nice features like a relay delay to prevent turn on "pops" and the like. Most of these 8 pin op amps run best on +/- 15 volts which is why Rod recommends it. Some op amps can go +/- 18 volts (36 volts the way you are looking at it) but that is pushing it for no reason as you don't need it for a line level crossover.
- Thread Starter
- #39
I had looked at it, even considered ordering it too, but I'm not too comfortable about building a PSU and eventually leave it unattended.
Plus there's already one laying around half unused.
Does it really make that of a difference three more volts?
Killingbeans
Major Contributor
I this case only the op-amps. You can look at their datasheets to see the electrical characteristics.
If the circuit had electrolytic capacitors on the supply rails, then the breakdown voltage of those would be a consideration. If it had its own voltage regulation, then the electrical characteristics of the regulator would overrule it all.
