Sounds really clear on my Sony studio monitors but I hear a metallic patina in the reverb of the vocal and wondering if it's due to the hard walls reflecting back into the mic. I still don't know how much of the sound is influenced by the crossover steup and whether it provides a consistent sound signature across all genre's of music including rock and other bands that have a lot of sounds playing over each other.
Just more general crossover setting information. I use passive crossovers on the Altec A7’s, which I added a super tweeter to. The tip comes from speaking with Al Klappenberger from ALK Engineering. You can do the math check all the graphs but successful crossover integration settings are up to the final arbitrators of sound, your ears. I spent a couple of weeks getting the shelving settings correct for the ALK passive crossovers. On Al's crossovers, you set the desired amount of HF attenuation by changing jumpers on an autoformer. After initially futzing around, I found a setting that I thought was correct. After listening a bit more, I decided it was a bit on the dark side. I used the next higher jumper setting on the chart that ALK supplied. Better, a bit more lively. But after playing around some more, I decided that the correct setting would be inbetween the two. As I looked on the chart, I found a basic pattern for the jumper settings. From the chart, I wondered, if I set this jumper here and that jumper there, I ought to get right between the two settings that were listed. I tried it and it worked! Absolutely spot on perfect! But with the tweeter attached, it would be throwing highs into the mix that would have thrown me off. If you are setting the crossovers on any system, you first have to set the crossover frequency and slope. Then you have to adjust the level between the woofer and the midrange. If you have a three-way system, you then have to adjust the volume shelving on the tweeter. This is the last step to take.
Everyone has a lack of knowledge, no one individual is an expert on every aspect of audio. You know (or should know) your own personal audio environment. Much like you know your own body. There is no audio expert on the planet that could enter my audio space, set up the gear I have, in the way I have done do and make it all play nicely together. I will typically run three pairs of speakers/power amps at one time. But it had taken me years to get to that point, making adjustments so that it works as a single cohesive and versatile system. There is way more to it than setting up a single pair of speakers and an amp. You can see in the forums how intricate in detail it takes to set up a single system.
If you have a three way speaker and want to experiment with active systems, then surely three way active is the only way to go?!
@OhioGraySky, I started to type, welcome to the forum and that I enjoyed your posts several pages ago, but the thread has taken off rather quickly! The effortless power and unrestrained dynamics is something I've always heard in (good) active systems. We often judge how loud something is by distortion, but when that distortion is not there.....
Thank you! Good to have found this place. That's an excellent point. Also, when you use drivers with more sophisticated (expensive) drive systems and there is much less power compression, it takes things to a whole new level dynamically.
Well, of course it does! That's a pearl free floating maple snare, right? It's a cannon of a snare. I have its cousin in brass, piccolo depth, and a rim shot can be painful!
Right! I bought my original one with a (6 1/2") brass shell, but it projected rather too well, so simply swapped the shell for a maple one. When I thought a spare was a good idea, I bought a second 6 1/2" Pearl maple free floater. A brass, piccolo barks beautifully and very loudly! You will know why a drum kit and cymbals are fantastic for appreciating the benefits of a great active system, with cymbals shimmering in their own space and still doing so when the bass drum and bass player are tunefully and with great feel, doing their own thing.
I’ll be honest I haven’t yet gotten my head around compression - both what causes it and how it sounds.
It's difficult to describe it. Being in a recording studio and applying it, you get to know the sound. I guess the best common example is to listen to an FM broadcast of music. They typically heavily compress everything to ensure they can broadcast the most signal without going out of band. It's when the music refuses to get louder past a certain threshold, even though dynamically it should. Tube amps tend to do it before clipping by rounding the wave more. Ever heard an analog tape that was recorded too loud? Everything gets shouty and "loud" and congested. It occurs to me that what we're really talking about is dynamic limiting, which is a form of compression. True compression boosts the quiet passages and limits the loud ones.
To me, compression means many things in regular life. Sometimes it's good. Like when you're compressing a sleeping bag in a stuff sack so you can fit it in a backpack with other things you need to stay alive when you're high up in the mountains at night. It's of no value in its stuffed state. The bag is of course is all still there when you unstuff it to sleep in later on. In other cases, compression means the loss of something so that it can fit in a limited space. Like a JPEG vs a RAW image from a digital camera. Once it's stored as a jpeg you can't get the RAW image back. Sometimes this important. But you always lose something in the process. So I'm trying to find an anchor point or two for thinking about compression in a musical context.
Interesting ideas there. Digital compression is a totally different thing, so no good analogy there. Think of that sleeping bag when the sack is getting full. You can only get so it so compacted. Think of musical dynamics as stuffing the bag. Compression happens when the mechanical or electrical system starts to decrease its output to a required input.
Think of analog compression as restricting the dynamic range of a song. This can be done on purpose or as a result of system issues. On the radio, music is compressed. This is so that there are no loud peaks. As previously mentioned, quiet passages are also boosted. This is so the quiet passages can be heard in a car over road noise. In audio, changes in the signal (voltage) should result in corresponding changes in output. When the changes in output level don't change in the way that you expect them to, then you are experiencing compression (provided these changes are less than you are expecting). This will typically happen when an amplifier runs out of steam and can no longer accurately represent the original signal.
The somewhat (im)famous version of the 1812 by Telarc took endless versions to get the right dynamic range for the music and the cannons and bell tower ringing at the end. It is one of the real tests of cartridge tracking ability and setup, with lesser cartridges just being thrown clear out of the groove. There is an image of the cannon shots on the record pressing here The Telarc 1812 Overture- Vinyl Engine .
I've been spending some time thinking about audio compression. In in particular thermal compression (aka power compression) in speakers, which is often considered as a form dynamic compression. (Disclaimer, most of what I write below will be absurdly obvious, assuming it's even correct, to the more advanced readers here. Which is most of you I think.) Dynamic compression exists for a variety of reasons and in a variety of forms. For example, dynamic compression is often used in studios or by radio stations to boost low signal and limit high signal to create more uniform volume. As @SandAndGlass and @OhioGraySky have mentioned above. It's use in the studio mastering process is illustrated here: And here's an interesting history of the use of various forms of compression in the music industry by Bob Katz: https://youtu.be/u9Fb3rWNWDA Looking past the fact that the use of dynamic compression techniques is controversial, it is at least intentional. Thermal compression in speakers is not. Or rather, it's an unavoidable and undesirable effect of the intentional use of passive crossovers and the thermal characteristics of speaker drivers. High quality passives can reduce thermal compression, which is I'm sure a point that @SandAndGlass would make if I didn't. And active bi-amping with line-level crossovers eliminates thermal compression from passive speaker crossovers (by eliminating the speaker crossovers). Of course you can't very well eliminate drivers from your speakers. So some amount of thermal compression is unavoidable. Although quality and design matter there too. As @OhioGraySky pointed out a while back: It's easy to visualize studio-introduced dynamic compression, as seen in the links above. Here's a particularly stark example: https://youtu.be/kwcr9qtDrsY But I've yet to see/hear similar examples of thermal compression. Which makes it difficult for someone like me who's trying to think about this for the first time understand what's happening with thermal compression. @OhioGraySky makes this point: Thermal compression occurs when speaker crossovers/coils heat up, resistance increases, and the audio signal get compressed, i.e. its dynamic range is restricted. Past a certain point, as volume is increased, the output volume does not increase, and sound quality suffers. Below that point it's still there, just at much lower and often inaudible levels. (More generally, "The harder you drive them, the less responsive they become." See link below.) But what does this look/sound like? Is the effect more similar to the distortion generated by light clipping, for example, than studio-introduced dynamic compression? I'm not trying to learn everything about it. Just trying to develop a working understanding of what it is and how impacts the music and add it to my general understanding of things. And hoping that anything the experts are able to offer will be of value to other curious readers. EDIT: Here is a wonderful write-up by Stereophile. It's helped provide a basic context and answered many (but obviously not all) of my questions. Hot Stuff: Loudspeaker Voice-Coil Temperatures
I took a couple of lame pictures of this section of the Telarc 1812 overture LP, in the archives Vinyl Torture Tracks - Inner Grooves, Sibilants, Hotly Cut Tracks, Sudden Volume Bursts, etc. Actually, this picture was intended to show the runout, but the wild grooves are clearly visible in the photo. And what it was playing on (which tracks it with no issue) Vinyl Torture Tracks - Inner Grooves, Sibilants, Hotly Cut Tracks, Sudden Volume Bursts, etc. If you don't want to follow the first link, here is the pic
Thermal compression is present, but is far less in the crossover than in the speaker driver. For a worst-case, here's the end of Madisound's 19ga air-core inductor list; 4mH would give a low 320Hz crossover: ... 2.00 2.0MHL 19 0.90 59 x 32 2.25 2.25MHL 19 0.95 59 x 32 2.50 2.5MHL 19 1.00 59 x 32 2.75 2.75MHL 19 1.05 59 x 32 3.00 3.0MHL 19 1.10 59 x 32 3.50 3.5MHL 19 1.20 59 x 32 4.00 4.0MHL 19 1.30 59 x 32 Compare the highest inductor's DC resistance of 1.30 ohms to the 6 ohm DC resistance typical of a speaker. 200 watts goes in? That's 165 watts to the voice coil; 35 watts to the crossover, when cold. When the voice coil rises 90 degrees F needed for a 20% increase in resistance, the inductor temperature doesn't rise much (1/5th the energy into much more copper mass glued to a circuit board), shifting the dissipation ratio even more towards the voice coil.
I don't believe that I have ever see a hot crossover? I have run my A7’s with fully exposed ALK crossovers and have never ever felt the slightest bit of warmth on the inductors or the caps. I imagine that it would take a lot of power to heat up any fair size crossover inductor? See post above! Any thermal compression you are likely to notice is at the voice coil of the speaker. More likely, if a speaker voice coil is exposed to too much power, it would not be able to dissipate heat properly and the voice coil would deform (permanently). It has little to nothing to do with crossovers that operate within their designed power range. Pro audio speakers are designed with a larger air gap in the voice coil structure and are designed to expand.
Slight challenge: Your ALK crossovers are highly evolved. What about lesser crossovers or the stock A7 crossover?
I can't speak of lesser crossovers as I have no personal experience with them. People buy Crites crossovers. This is fine, but be aware that while they might offer some degree of improvement over the factory Klipsch crossovers, they are basically recreations of the original factory crossovers using better modern capacitors. ALK crossovers are completely different in design and are not comparable to the original Klipsch crossovers in any way. I am on my way to work and will address the Altec crossovers later on this evening.
BTW, I just want to say that I really appreciate all your input. I think it's incredibly valuable in terms of keeping this thread balanced and to me personally as I endeavor to understand all this madness. I like challenging you from time to time but that's largely because there is always value in your responses. Just want you to know that.
Read about proximity effect. DCR of an inductor is not a good guide - AC resistance in the audio band is much higher than DCR, and increases rapidly with frequency. But indeed thermal compression in drivers is a significant effect too.
