Howdy,
I'm on the road to tri-amping better. Right now, I've got an analog 2-way active crossover and a sub-amp hooked up speaker level off the mid-bass amp.
I want to protect my mid-bass woofers from very low frequencies, and I have the superstition that speaker level connection affects the performance of the mid-bass amp
In getting familiar with DSP products/options marketed for home stereo use, I began to wonder.... What is in fact the difference between for example a minidsp, or that category of product, and a full-bore audio interface designed for recording? If I need an ADC/DAC with on-board DSP... Isn't that an audio interface?
If I need at least 6 out to tri-amp, that's a pretty high price point market in DSP's. We're looking at 800, and all the way up to thousands. 800 will get you into a pretty freaking nice, entry-level-pro interface. I could get a used ferrofish 16/16 for the price of a 4/10 minidsp... They've got um that don't need to be computer connected to function as well, like consumer stereo DSP products.
So, why don't more people do this? I can't barely find any representation of this idea online, but it doesn't help that there's an actual audio interface brand called "bi-amp." Really messes with those googler results.
It seems like you can spend less money and get more features, and the ability to record in fantastic quality...
But can an audio interface run these filter processes, on the on-board DSP, zero latency? Not on the DAW? I don't know anything about like, computers, digital stuff, so I don't know the answer. I don't have one lying around to play with...
Wondering if anyone has the knowledges.
I'm ignorant enough that I don't know if this is just a bad idea, or standard practice.
Thanks and stuff,
A hack
I'm on the road to tri-amping better. Right now, I've got an analog 2-way active crossover and a sub-amp hooked up speaker level off the mid-bass amp.
I want to protect my mid-bass woofers from very low frequencies, and I have the superstition that speaker level connection affects the performance of the mid-bass amp
In getting familiar with DSP products/options marketed for home stereo use, I began to wonder.... What is in fact the difference between for example a minidsp, or that category of product, and a full-bore audio interface designed for recording? If I need an ADC/DAC with on-board DSP... Isn't that an audio interface?
If I need at least 6 out to tri-amp, that's a pretty high price point market in DSP's. We're looking at 800, and all the way up to thousands. 800 will get you into a pretty freaking nice, entry-level-pro interface. I could get a used ferrofish 16/16 for the price of a 4/10 minidsp... They've got um that don't need to be computer connected to function as well, like consumer stereo DSP products.
So, why don't more people do this? I can't barely find any representation of this idea online, but it doesn't help that there's an actual audio interface brand called "bi-amp." Really messes with those googler results.
It seems like you can spend less money and get more features, and the ability to record in fantastic quality...
But can an audio interface run these filter processes, on the on-board DSP, zero latency? Not on the DAW? I don't know anything about like, computers, digital stuff, so I don't know the answer. I don't have one lying around to play with...
Wondering if anyone has the knowledges.
I'm ignorant enough that I don't know if this is just a bad idea, or standard practice.
Thanks and stuff,
A hack
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I think some of the larger audio IO boxes from Focusrite or MOTU have software plugins, but you are buying a lot of mic input capability you don't need. For what they can do, might call Sweetwater and talk to them. Most only have 4 line outs though ( balanced of course) I believe there are some soundcards that have 10 or so channels, but I know nothing about their software or quality. The "affordable" semi-pro IO boxes are amazingly good for the price, but not the equal if the "real" stuff. They are not "entry pro" but more like basement band or blogger stuff. Add zero's for the actual pro stuff. I have a Focusrite 2i2 and it was better than my old MUSE DAC, but not the equal of my JDS or Schiit. Everyone hears something different, so they may be fine for you. Specs help and they don't lie, but don't tell the whole truth either.
MiniDSP seems to be the SOP. The 4 x 10 would do what you want. It is not quite the quality of the new FLEX though. I am waiting for the FLEX digital so I can run my preferred DACs. ( JDS Atom Plus) I wish they would make a larger FLEX, 2 x 3 and 2 x 4 digital. It would be killer.
You don't need zero latency, you just need all the channels the same. Besides, zero is impossible. Even in analog. Pro stuff uses an external atomic clock to keep everything in sync.
I am not a big DSP fan. I prefer analog crossovers but you can't manage acoustic offset with them so I am waiting for the FLEX to be in stock. I would have to cascade two. The unit I would never run again is the Behringer DCX. Gad it was terrible. Don't think the DBX is any better.
MiniDSP seems to be the SOP. The 4 x 10 would do what you want. It is not quite the quality of the new FLEX though. I am waiting for the FLEX digital so I can run my preferred DACs. ( JDS Atom Plus) I wish they would make a larger FLEX, 2 x 3 and 2 x 4 digital. It would be killer.
You don't need zero latency, you just need all the channels the same. Besides, zero is impossible. Even in analog. Pro stuff uses an external atomic clock to keep everything in sync.
I am not a big DSP fan. I prefer analog crossovers but you can't manage acoustic offset with them so I am waiting for the FLEX to be in stock. I would have to cascade two. The unit I would never run again is the Behringer DCX. Gad it was terrible. Don't think the DBX is any better.
Thank you for the information, very helpful. I'm not very fond of digital either, if the source is analog. If it's coming from a computer anyways that's fine, but it would make me cringe a bit to run vinyl into a digital box and back out.
I'm wondering, in analog active crossovers, do you have any strong opinions about specific units? How much better than my Ashly sc22 will it get on a budget? I need a steeper slope for sure, I'm hoping to get up to 48db/octave...
I hack my way through building and working on tube amplifiers, and I have the intention to build a tube-based crossover a la luxman a2003 - but so far I've just run into a lot of holes in my understanding and vocabulary, and it's going to be a long road I think. I've got some of the important transformers, but right now I'm getting over the hurdle of my first unity gain stage.... That doesn't suck anyways.
I'm wondering, in analog active crossovers, do you have any strong opinions about specific units? How much better than my Ashly sc22 will it get on a budget? I need a steeper slope for sure, I'm hoping to get up to 48db/octave...
I hack my way through building and working on tube amplifiers, and I have the intention to build a tube-based crossover a la luxman a2003 - but so far I've just run into a lot of holes in my understanding and vocabulary, and it's going to be a long road I think. I've got some of the important transformers, but right now I'm getting over the hurdle of my first unity gain stage.... That doesn't suck anyways.
Not sure there is much real need to go steeper than 4th order unless using some really horrible breakup mids, and then a notch is more often used. 48 would be a lot of stages as usually you get two orders per stage. Every order increases the phase mess. I played with 6th order when I had that most terrible DCX2496 and found it not very helpful even on Dayton RS aluminum cones.
Have you looked at Self or the older Lancaster and Jung books on OP-Amps? They will give you a lot if information on filer topology which you could adapt to tubes. I remember some circuits way back using FETS. Seems one of them might have used inductors and caps, not gyrators. Popular Electronics, pre 1970 I think.
How do you intend to deal with baffle step compensation?
How do you intend to deal with time alignment?
How do you intend to deal with phase shift?
As far as an analog solid state pre-built upgrade, the Sublime looks pretty good. Cleaner than my X-Kitz. It should be in the totally transparent range.
https://sublimeacoustic.com/products/k231-stereo-3-way-active-crossover
Your Ashley is a typical old SS low end PA crossover. I used a Behringer and a DBX for a while. They sound like cheap Chinese op-amps. One can rebuild them with far better parts but replacing SMT caps with good films can be a real pain. Cheap pots, poor PS filtering, etc. I considered that but when I totaled everything up, all I was using was the case.
Just my 2 cents, I don't think I would take on a crossover with tubes. IF you can get decent tubes, I am not sure that is much advantage. Even a 4th order, you probably need 16 tube stages for a two way between buffers, filters and drivers and that does not include if you want a HP on the woofer.
If solidly DIY, don't forget how you can add filtering in various places in your preamp and power amps reducing the steepness needed in a crossover. Think system, not unit. Also don't forget hybrid. You always want a blocking cap on your tweeter even with an electronic crossover, so go ahead and use it as a first order. Some still use Zobels to make the drivers easier to drive, so make use of them.
Best of luck.
Have you looked at Self or the older Lancaster and Jung books on OP-Amps? They will give you a lot if information on filer topology which you could adapt to tubes. I remember some circuits way back using FETS. Seems one of them might have used inductors and caps, not gyrators. Popular Electronics, pre 1970 I think.
How do you intend to deal with baffle step compensation?
How do you intend to deal with time alignment?
How do you intend to deal with phase shift?
As far as an analog solid state pre-built upgrade, the Sublime looks pretty good. Cleaner than my X-Kitz. It should be in the totally transparent range.
https://sublimeacoustic.com/products/k231-stereo-3-way-active-crossover
Your Ashley is a typical old SS low end PA crossover. I used a Behringer and a DBX for a while. They sound like cheap Chinese op-amps. One can rebuild them with far better parts but replacing SMT caps with good films can be a real pain. Cheap pots, poor PS filtering, etc. I considered that but when I totaled everything up, all I was using was the case.
Just my 2 cents, I don't think I would take on a crossover with tubes. IF you can get decent tubes, I am not sure that is much advantage. Even a 4th order, you probably need 16 tube stages for a two way between buffers, filters and drivers and that does not include if you want a HP on the woofer.
If solidly DIY, don't forget how you can add filtering in various places in your preamp and power amps reducing the steepness needed in a crossover. Think system, not unit. Also don't forget hybrid. You always want a blocking cap on your tweeter even with an electronic crossover, so go ahead and use it as a first order. Some still use Zobels to make the drivers easier to drive, so make use of them.
Best of luck.
Thank you again, yes I do need the reading, and I appreciate being pointed to the right books. Most of what I've got in touch with is written by/for engineers and, I'll need to reference other material about 17 times per page mostly on account of math, which leads me to abandoning the book 3 chapters in you know... I just bought Morgan Jones' Valve Amplifiers and that is going better. Olson's Elements of Acoutical Engineering.... not so well lol.
OT: In college they shoved me into a 300 level course my first semester and I never took another math course... scarred for life... Why do Americans treat mathematics as an inherent talent rather than developed skill? You're supposed to "get it" on your own, or get out, from very early grades around 10 or 12 years old you start to encounter this attitude amongst educators... The professor of that class told me frankly, to paraphrase, that undergrad courses in "hard" sciences are not for teaching, they are impediments or obsticles set up to seperate the wheat from chaff, and in grad school they'll take the time to teach you, because they know you're worth it. What a waste of money... Ok, that's all for off topic...
Maybe I don't need a steeper slope, but a better x-over unit. I can just hear vocal range stuff at the subwoofer. Sounds abnormal. Phase issues because of the overlap with midwoofers.
"How do you intend to deal with baffle step compensation?"
Well, I had to google "baffle step compensation" so I'll get back to you on that... heh...
"How do you intend to deal with time alignment?"
I supposed that with a fairly small system in a fairly small environment, I'd get away with physical placement adjustments. This is inexperience talking though. I'm only aware of time smear from driver placement... Let me describe the setup, first. I have one per channel 15" Jensen a15pm's (repaired, non-original fresh cones) running on a SET 6a5g amp 3.75w per channel. I have a variety of high efficiency mid-range compression drivers (I can elaborate on that if you want), all antiques truly. Which pair determines the crossover point from the a15pm's, which seem very flexible and sound wonderful up into midrange. The amp for those is an SET 45 amp, maybe 2.5w per channel and plenty at that. Tweeters are JBL alnico 2405's with a single 1.0uf cap. It is a simple thing to set each channel up on-axis and tightly grouped, probably 24" max from midwoofer center to the center of the horn. 2405 is hanging off the edge of the horn mouth. Subwoofer is running mono and goes front and center, I have one JBL 2242hpl running on a Hafler p3000 bridged. Right now it's in a simple ported box, but I want to build a horn similar to the JBL ash6118.
But, how I will correct for time smear from the crossover, I do not know. Right now I'm doing nothing.
"How do you intend to deal with phase shift?"
You guessed it, right now I'm doing nothing, and I am not familiar with how this is dealt with outside of the digital world. Fuzzy on how that is done, too. Really most professional pa practices are outside of my awareness. I'd probably learn alot just looking at some block diagrams of people's rigs (but there's always a dbx260 lol), or gaining a friend in pro audio who wants to talk shop at me. Maybe try to get a roadie gig and annoy the sound guy constantly. Similar to what I do on forums lol.
You don't really run into "clocks" gigging around locally in high school, playing dive bars and stuff. And that's pretty much the extent of my exposure. Around here these days I see most bands using crap like Bose line arrays mixed on an ipad, without a tech at all. Who can afford one? And at big shows those guys are too busy to bother 'em.
Again, thank you and, you've definitely given me enough material to get me started, no need to invest more time unless you're dying to.
OT: In college they shoved me into a 300 level course my first semester and I never took another math course... scarred for life... Why do Americans treat mathematics as an inherent talent rather than developed skill? You're supposed to "get it" on your own, or get out, from very early grades around 10 or 12 years old you start to encounter this attitude amongst educators... The professor of that class told me frankly, to paraphrase, that undergrad courses in "hard" sciences are not for teaching, they are impediments or obsticles set up to seperate the wheat from chaff, and in grad school they'll take the time to teach you, because they know you're worth it. What a waste of money... Ok, that's all for off topic...
Maybe I don't need a steeper slope, but a better x-over unit. I can just hear vocal range stuff at the subwoofer. Sounds abnormal. Phase issues because of the overlap with midwoofers.
"How do you intend to deal with baffle step compensation?"
Well, I had to google "baffle step compensation" so I'll get back to you on that... heh...
"How do you intend to deal with time alignment?"
I supposed that with a fairly small system in a fairly small environment, I'd get away with physical placement adjustments. This is inexperience talking though. I'm only aware of time smear from driver placement... Let me describe the setup, first. I have one per channel 15" Jensen a15pm's (repaired, non-original fresh cones) running on a SET 6a5g amp 3.75w per channel. I have a variety of high efficiency mid-range compression drivers (I can elaborate on that if you want), all antiques truly. Which pair determines the crossover point from the a15pm's, which seem very flexible and sound wonderful up into midrange. The amp for those is an SET 45 amp, maybe 2.5w per channel and plenty at that. Tweeters are JBL alnico 2405's with a single 1.0uf cap. It is a simple thing to set each channel up on-axis and tightly grouped, probably 24" max from midwoofer center to the center of the horn. 2405 is hanging off the edge of the horn mouth. Subwoofer is running mono and goes front and center, I have one JBL 2242hpl running on a Hafler p3000 bridged. Right now it's in a simple ported box, but I want to build a horn similar to the JBL ash6118.
But, how I will correct for time smear from the crossover, I do not know. Right now I'm doing nothing.
"How do you intend to deal with phase shift?"
You guessed it, right now I'm doing nothing, and I am not familiar with how this is dealt with outside of the digital world. Fuzzy on how that is done, too. Really most professional pa practices are outside of my awareness. I'd probably learn alot just looking at some block diagrams of people's rigs (but there's always a dbx260 lol), or gaining a friend in pro audio who wants to talk shop at me. Maybe try to get a roadie gig and annoy the sound guy constantly. Similar to what I do on forums lol.
You don't really run into "clocks" gigging around locally in high school, playing dive bars and stuff. And that's pretty much the extent of my exposure. Around here these days I see most bands using crap like Bose line arrays mixed on an ipad, without a tech at all. Who can afford one? And at big shows those guys are too busy to bother 'em.
Again, thank you and, you've definitely given me enough material to get me started, no need to invest more time unless you're dying to.
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Oh, I forgot to say, my tube amps are self built, and I play around in the guts constantly. I'm not shy of making changes just to hear them. I didn't even think of this but, yes I could integrate filtration into the line stage. Kinda like a guitar amp... Hmm...
I'm going to try this, and I can't start trying something without finding the walls. Let's see how far I can take this. I wonder If I can just do the whole job in the amp... Of course, the crossover point will be fixed, but that's the case on the nice analog units anyways, and definitely the case for a tube design... Which is on the back-burner for now...
I could probably get a fat corn cob rotary and give the amp three or four crossover points... If it goes well, we will see.
I'm going to try this, and I can't start trying something without finding the walls. Let's see how far I can take this. I wonder If I can just do the whole job in the amp... Of course, the crossover point will be fixed, but that's the case on the nice analog units anyways, and definitely the case for a tube design... Which is on the back-burner for now...
I could probably get a fat corn cob rotary and give the amp three or four crossover points... If it goes well, we will see.
I do commend you for understanding it is not a simple plug and play process. We get so many who do not want to put any effort in and expect to build a $50,000 system killer right off. It is engineering and does need math ( but simulators do most of that for you). Fortunately, mostly just algebra, though you need to understand imaginary numbers. Math is after all the language of nature. I only made it through Calc 1, so I am no expert mathematician.
Also might look at the old Siegfried Linkwitz site for technical descriptions on filters. Maybe too much, but at least it is free!
A proper crossover deals with both the acoustic offset and any phase added by the crossover. For instance, my mains ( Seas ER18 and TTFCG) are actually correct on a flat baffle with an asymmetric 2nd/3rd order passive crossover with BSC. Again, you have to look at as a system with everything in play. ( I tried them on an old HK Citation something. 12W. Way too inefficient. I run a modified Hafler 120 now.
We usually model active circuits in Spice. I prefer LTSpice but others use different ones. Again free, but you do need to understand what you are modeling. I know there are models for some tubes as I have seen it mentioned on the forum.
PS: From a few concerts I have been to, I suggest many of the sound guys know less than you do. I walked out on some and was so aggravated at a Moody Blues concert I was about to go push the engineer out of the way and fix it! The band actually stopped a couple of times to yell at the engineer.
Might I suggest as you have the power, a low Q sealed box for the sub. A sub horn is very big. VERY big. A low Q, .5 is called "critical Q" blends with the room much better requiring far less eq if any. Google it. Model the sub in HornResp and see. Then see if it can work in a sealed box. I use WinISD. Do you really need a sub with those Jensens?
Also might look at the old Siegfried Linkwitz site for technical descriptions on filters. Maybe too much, but at least it is free!
A proper crossover deals with both the acoustic offset and any phase added by the crossover. For instance, my mains ( Seas ER18 and TTFCG) are actually correct on a flat baffle with an asymmetric 2nd/3rd order passive crossover with BSC. Again, you have to look at as a system with everything in play. ( I tried them on an old HK Citation something. 12W. Way too inefficient. I run a modified Hafler 120 now.
We usually model active circuits in Spice. I prefer LTSpice but others use different ones. Again free, but you do need to understand what you are modeling. I know there are models for some tubes as I have seen it mentioned on the forum.
PS: From a few concerts I have been to, I suggest many of the sound guys know less than you do. I walked out on some and was so aggravated at a Moody Blues concert I was about to go push the engineer out of the way and fix it! The band actually stopped a couple of times to yell at the engineer.
Might I suggest as you have the power, a low Q sealed box for the sub. A sub horn is very big. VERY big. A low Q, .5 is called "critical Q" blends with the room much better requiring far less eq if any. Google it. Model the sub in HornResp and see. Then see if it can work in a sealed box. I use WinISD. Do you really need a sub with those Jensens?
I want to get into the spice. I thought that, with ancient drivers, it's really necessary to have a measurement mic and to make a model of the driver based on the spl curve. I don't know how to do that yet, and don't have a measurement mic, but it's in my future for sure. For modeling the amps - I guess I just have to plug in the values for the tubes off the data sheet and draw up the schematic in the software.
I definitely see that really competent techs have a massive amount of experience. I would like to be quite capable of taking pa gigs and turning it into a part time nights/weekends job, but on a five year plan. I don't expect to become an expert overnight. It took me years of work and a lot of failure to gain legitimate skill in what I do professionally (gardening, "permaculture consultation" on my tax form lol). I know that real ability is paid for on a long time scale.
I'm reading on that linkwitz site, and there is a ton there for me to digest.
The sub comes into play with modern bass. Unnaturally low frequencies from digital instruments. I have to say, I love these Jensen's, one is pre-date code and one 1947. With any older recordings, even bass heavy stuff like dub and reggae, they hold it down. But when someone wants to put on desert dwellers, or grimes or, even maybe 90s ska which I'm fond of, they won't go that low. Really any hip hop... And I worry about their rigid surround with the excursion. Great speaker tech in my area though, a re-cone on those is super affordable.
I find surprisingly bad live sound a lot too. I was recently impressed by a Funktion rig, those systems are quite nice. The projection & dispersion of the midrange was so good, I was drawn in from chatting in the lot by the sound check. Generic b&c drivers tho I hear. Must be the horns.
The midrange I'm the most stoked on is the RCA 9584, got them out of WWII naval loudspeakers. They're loaded on 30's Dukanes from a movie theater, tuned to about 500hz, estimated based on dimensions. They are super cool looking parabolic single cell. They're made of a bitumen hard rubber compound, really nice.
Also big on a pair of Jensen manufactured 720a clones, also from WWII naval loudspeakers lol. Those are on some 3d printed short multicells that I need to tar up. They're tuned to 700. The replacement diaphragms are harder to get than the RCA tho so they don't really leave the house.
I definitely see that really competent techs have a massive amount of experience. I would like to be quite capable of taking pa gigs and turning it into a part time nights/weekends job, but on a five year plan. I don't expect to become an expert overnight. It took me years of work and a lot of failure to gain legitimate skill in what I do professionally (gardening, "permaculture consultation" on my tax form lol). I know that real ability is paid for on a long time scale.
I'm reading on that linkwitz site, and there is a ton there for me to digest.
The sub comes into play with modern bass. Unnaturally low frequencies from digital instruments. I have to say, I love these Jensen's, one is pre-date code and one 1947. With any older recordings, even bass heavy stuff like dub and reggae, they hold it down. But when someone wants to put on desert dwellers, or grimes or, even maybe 90s ska which I'm fond of, they won't go that low. Really any hip hop... And I worry about their rigid surround with the excursion. Great speaker tech in my area though, a re-cone on those is super affordable.
I find surprisingly bad live sound a lot too. I was recently impressed by a Funktion rig, those systems are quite nice. The projection & dispersion of the midrange was so good, I was drawn in from chatting in the lot by the sound check. Generic b&c drivers tho I hear. Must be the horns.
The midrange I'm the most stoked on is the RCA 9584, got them out of WWII naval loudspeakers. They're loaded on 30's Dukanes from a movie theater, tuned to about 500hz, estimated based on dimensions. They are super cool looking parabolic single cell. They're made of a bitumen hard rubber compound, really nice.
Also big on a pair of Jensen manufactured 720a clones, also from WWII naval loudspeakers lol. Those are on some 3d printed short multicells that I need to tar up. They're tuned to 700. The replacement diaphragms are harder to get than the RCA tho so they don't really leave the house.
As a complete newbie to diy audio with a small budget, I bought a used 8-channel high quality soundcard and let the free Equalizer APO software do the DSP/ crossover/ equalizing/ etc. (this software is really mighty, and more flexible than a hardware DSP). So I could route 3 channels to the right and 3 channels to the left box + 1 channel for the subwoofer. As amplifiers I use 3 LM3886 per box and 2 TDA7293 in parallel for the sub. The overall costs were really low, and the result is surprisingly good. I love it 😉 .
I have used a MOTU interface with onboard DSP. Soundquality was amazing but the DSP missed delay, so not as versatile as dedicated crossover dsp, and also quite tricky routing etc
Parts express has a unit with both analog in and digital plus Wi-Fi with 8 individually controllable outputs. It’s under $200 too. There are both frequency and slope controls. A parametric eq and delay adjustment. Worth a try, I use one with great results. It’s a DSP-408 and on sale right now.
With the right software and a multichannel output DAC one can fairly easily do this.
I have PureMusic & an Edirol Firewire DAC with 6 vhsnnels out at 24/192.
https://www.roland.com/global/products/fa-101/
Volume needs to be controlled at the computer or you will need some sort of many gang pots.
dave
I have PureMusic & an Edirol Firewire DAC with 6 vhsnnels out at 24/192.
https://www.roland.com/global/products/fa-101/
Volume needs to be controlled at the computer or you will need some sort of many gang pots.
dave