Need Basic Setup Info for 2 way 3 driver active crossover setup

Emerald_Metaphor

Emerald_Metaphor

Audiophyte
Hello, I need some basic info about setting up the Dayton DSP-408 between my Marantz DAC/preamp using the DAC's variable outs (for final system volume control), and my 2 power amps vertically (one amp runs mid/highs and other runs low of both speakers, respectively, but it seems to me all channels are the same (fungible) and for this each can be thought of as completely independent, so in this case vertical = horizontal, i.e. I can also run one amp per speaker, one channel to mid-hi the other to low, and same with other amp for the other speaker, it is a "same-difference", horizontal versus vertical setups with identical amps in a biwired 2 way system degnerate to equivalence, as if there were always just 4 physically separate mono amps, 2 channels filtered to the highs, 2 channels to the mid-lows, just don't accidentally port the signal thru the right filter for the wrong drivers with their passive networks disabled, poof go my tweeters).

My speakers, 40 year old Snell Type A's, no's 705 and 706!!!, were apparently the first speaker model ever designed to be vertically bi-amped, which I plan to do later with a Dynaco ST-70 (original refurbished) and one of my NAD C270's (other amp is a C370, same power stage, integrated preamp bypassed, although I can run my DAC in fixed output mode too, and use the NAD 370's preamp instead, but this doesn't change my configuration or questions really, it is simply something I could try to see if it makes my sound different, errr, I mean BETTER, lol).

Now, I have no issues with setting up the routing and crossovers and physical cables, and largely want to get this active biamping going in a flat (EQ off) and minimally ideal gain configuration, just for proof of concept in terms of hearing the expected improvements, before I dare to use 2 different amps (here I might pay someone to help with gain matching and tuning). I do still need to actively prefilter both a low pass on the 2 woofer output channels and also a hi-pass for the 2 mid-high outs (and have the numbers recommended by Snell to do so).

Also, as recommended by Snell, I am only disabling/bypassing (with provided shorting plugs) the woofer filter network to start (just a bass driver, not a sub, but 10 inches and downfiring, nominal by-pass point for this 2 way to 3 driver set up is 275 Hz, with a 4 times overlap correction factor, I am instructed to set the hi pass to 69Hz, the low pass to 1100 Hz, again as per the manual for these speakers when biamped). This, at the very least, gives me the 3dB bass channel gain improvement and should improve bass noticeably all by itself. I did try with a used analog crossover first, but it or the XLR to RCA adapters had issues, the crossover ate all the bass power somewhere (it cut in and out when changing the volume from the DAC/preamp, and I had to go higher, not lower volume, the opposite of what was expected), but the mids and highs did sound more transparent, so that was encouraging). Unless I am sure the settings on my DSP match those of Snell's hard to find custom active crossover (so the question is whether the specs in the doc are also what the custom active crossover is physically set too, or are these settings just meant for 3rd party active crossovers, this remains ambiguous???).

So, I am clearly advised to keep the mid-hi passive network active (I am trying to buy the custom one used, there is one out there, but I haven't heard back from the seller, using this I can bypass both filter networks without using a DSP, somehow, not sure why I can't with a DSP set with the same hi and low pass 2 way values??? I am guessing the tweeter has something that can't be bypassed in front of it for meshing with the custom active crossover in place and the passive mid-hi network bypassed, but it is very hard to find that info now). So be it.

My issues start with trying to understand how to set all the (3 levels of) volume control, both on the 4 output channels, on my DAC/Preamp to set the DSP up, and finally on the master volume in the app. I have no standard external gain adjustments on my NAD's as car amps have, they are fully on power amps (the 370 does have a variable RCA input too, but not the 270).

So FIRST: I am unclear if my preamp or the DSP app ends up controlling the final listening volume, and SECOND I am looking for some way to set all these controls to some standard sort of ideal defaults (output channels at full, master app volume at 0 dB???), i.e. minimally configure the DSP just enough so I can safely connect my speakers and make small real-time adjustments with actual music instead (try different filters, slopes, slightly tweak the filter frequency settings, etc.). This is where I am stumped. Do I really need extra testing equipment here, I have a tone and pink noise generator on my PC, and given my amps are identical should have no need to gain match, EQ, or adjust delays, just set the overall system to some flattened and safe ideal to start, so I can finally connect my speakers safely and do minor tweaks from there. Thanks! Brian.
 
Last edited:
everettT

everettT

Audioholic Spartan
If you're gonna run those speakers actively not passively, disconnect the passive crossovers and start correctly..
 
TLS Guy

TLS Guy

Seriously, I have no life.
Hello, I need some basic info about setting up the Dayton DSP-408 between my Marantz DAC/preamp using the DAC's variable outs (for final system volume control), and my 2 power amps vertically (one amp runs mid/highs and other runs low of both speakers, respectively, but it seems to me all channels are the same (fungible) and for this each can be thought of as completely independent, so in this case vertical = horizontal, i.e. I can also run one amp per speaker, one channel to mid-hi the other to low, and same with other amp for the other speaker, it is a "same-difference", horizontal versus vertical setups with identical amps in a biwired 2 way system degnerate to equivalence, as if there were always just 4 physically separate mono amps, 2 channels filtered to the highs, 2 channels to the mid-lows, just don't accidentally port the signal thru the right filter for the wrong drivers with their passive networks disabled, poof go my tweeters).

My speakers, 40 year old Snell Type A's, no's 705 and 706!!!, were apparently the first speaker model ever designed to be vertically bi-amped, which I plan to do later with a Dynaco ST-70 (original refurbished) and one of my NAD C270's (other amp is a C370, same power stage, integrated preamp bypassed, although I can run my DAC in fixed output mode too, and use the NAD 370's preamp instead, but this doesn't change my configuration or questions really, it is simply something I could try to see if it makes my sound different, errr, I mean BETTER, lol).

Now, I have no issues with setting up the routing and crossovers and physical cables, and largely want to get this active biamping going in a flat (EQ off) and minimally ideal gain configuration, just for proof of concept in terms of hearing the expected improvements, before I dare to use 2 different amps (here I might pay someone to help with gain matching and tuning). I do still need to actively prefilter both a low pass on the 2 woofer output channels and also a hi-pass for the 2 mid-high outs (and have the numbers recommended by Snell to do so).

Also, as recommended by Snell, I am only disabling/bypassing (with provided shorting plugs) the woofer filter network to start (just a bass driver, not a sub, but 10 inches and downfiring, nominal by-pass point for this 2 way to 3 driver set up is 275 Hz, with a 4 times overlap correction factor, I am instructed to set the hi pass to 69Hz, the low pass to 1100 Hz, again as per the manual for these speakers when biamped). This, at the very least, gives me the 3dB bass channel gain improvement and should improve bass noticeably all by itself. I did try with a used analog crossover first, but it or the XLR to RCA adapters had issues, the crossover ate all the bass power somewhere (it cut in and out when changing the volume from the DAC/preamp, and I had to go higher, not lower volume, the opposite of what was expected), but the mids and highs did sound more transparent, so that was encouraging). Unless I am sure the settings on my DSP match those of Snell's hard to find custom active crossover (so the question is whether the specs in the doc are also what the custom active crossover is physically set too, or are these settings just meant for 3rd party active crossovers, this remains ambiguous???).

So, I am clearly advised to keep the mid-hi passive network active (I am trying to buy the custom one used, there is one out there, but I haven't heard back from the seller, using this I can bypass both filter networks without using a DSP, somehow, not sure why I can't with a DSP set with the same hi and low pass 2 way values??? I am guessing the tweeter has something that can't be bypassed in front of it for meshing with the custom active crossover in place and the passive mid-hi network bypassed, but it is very hard to find that info now). So be it.

My issues start with trying to understand how to set all the (3 levels of) volume control, both on the 4 output channels, on my DAC/Preamp to set the DSP up, and finally on the master volume in the app. I have no standard external gain adjustments on my NAD's as car amps have, they are fully on power amps (the 370 does have a variable RCA input too, but not the 270).

So FIRST: I am unclear if my preamp or the DSP app ends up controlling the final listening volume, and SECOND I am looking for some way to set all these controls to some standard sort of ideal defaults (output channels at full, master app volume at 0 dB???), i.e. minimally configure the DSP just enough so I can safely connect my speakers and make small real-time adjustments with actual music instead (try different filters, slopes, slightly tweak the filter frequency settings, etc.). This is where I am stumped. Do I really need extra testing equipment here, I have a tone and pink noise generator on my PC, and given my amps are identical should have no need to gain match, EQ, or adjust delays, just set the overall system to some flattened and safe ideal to start, so I can finally connect my speakers safely and do minor tweaks from there. Thanks! Brian.
Ok from my research this is a solvable problem. These speakers HAD to be biamped. There is a bass section, and then mid HF sections. Now the internal crossovers of the mid/HF sections MUST NOT be bypassed. They also roll off the bass at 350 Hz. Now since there is a passive crossover at 375 Hz rolling off the mids, then you should not double up with an active crossover. However many do advise using and active high pass at 70 Hz 24 db. per octave to better protect the mids. This is well below the mids passive roll off and will not affect the audible response.

The bass section requires a 24 db. per octave low pass filter at 350 Hz.

Now one other caveat here. I would use the two NAD amps, as it is likely they will have an identical phase response in respect of the input and output signals.
I would not use that Dynaco ST 70 tube amp. That has an output transformer and I can be certain that it will have a different phase response versus the NAD amps. So that would lead to bad results combined with a NAD amp.

It is pretty clear to me from your rambling post that your thoughts are far from clear.

I have given you the absolute correct information. I was around back then. I also know what I'm doing and I'm not convinced you do. So I am going to tell you straight up, I am not going to get into any lengthy arguments with you.

I have told you exactly and precisely how to set this up, and now it is up to you to implement it.
 
Emerald_Metaphor

Emerald_Metaphor

Audiophyte
Yes, but what you (meant) said is what I (meant) said, so I find you are quite arrogant and I will say thanks for confirming what I said, but you have failed to understand me much here either. I expect if my attempt to mean is unclear this is stated first BEFORE dumping on me, pointing to what is unclear as to help me CLARIFY for you to understand me better, but you seem to want to get right to being a judgmental jerk, seriously man, kettle pot black in regards the the tone and focus of your reply. If you had done this rather than punishing me for trying you would have understood that using the Dynaco in a vertical mode is not what I am trying now, for exactly the possible reasons you've suggested. So maybe I need a different tube amp for the mid-hi, which is supposed to be a ideal setup, assuming the 2 amps can be gain and sensitivty matched. I am new to this particular stuff, yes, but do have a degree in Physical Science, and once knew all this better. You have not provided the info i really need about default gain settings for safe tweaking, Again, you are being very arrogant, unkind and aggressive, so can you try and be a bit more decent here, before I bow down to your expertise, this looks like trolling a bit to me, ok? Silence is fine too. I already regret signing up, thanks to your behaviour. I reported you for this. Your advice is unwelcome going foward, you are not the communicator you fancy yourself, but probably live under a very nice bridge. Finally, I will be following Snell's specs, not yours, why wouldn't I?
 
Emerald_Metaphor

Emerald_Metaphor

Audiophyte
If you're gonna run those speakers actively not passively, disconnect the passive crossovers and start correctly..
Well, if you understood all that I said, Snell CLEARLY says to only disable the bass one unless the crossover is properly set AND is approved by them, no way to know that know, but they make it clear to then only disable the bass, so you missed that, and I will start with the mid-hi network active until I am sure the system is stable and find some way to confirm I can do so (also trying to source an original custom Snell crossover, would be plug and play for identical amps and then I can disable both networks, but need to make new shorting plugs, i.e. they only provide one set to prevent easily disabling both, you can consult the same two manuals and reviews online, all confirm and are consistent with what I said before I got to my questions. You did not read all the way thru , clearly, and that is a problem in my opinion too, no one seems to answer the 2 questions at the end, or even note them, the dense preliminary part is right, whether people think it is or not, I simply need to know about volume control and gain setting, the rest I have confirmed from multiple sources of info and the config of the porting and filters is easy enough, but thanks for not being like the guy after you. Horrible behaviour for my first reply, why I hate even doing this stuff online anymore, and I was one of the first on the Oregon Trail programming in machine code in 1983, now I hate the internet and most tech, and increasing amounts of humanity, and I am not wrong to either, lol, col!
 
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Emerald_Metaphor

Emerald_Metaphor

Audiophyte
Ok from my research this is a solvable problem. These speakers HAD to be biamped. There is a bass section, and then mid HF sections. Now the internal crossovers of the mid/HF sections MUST NOT be bypassed. They also roll off the bass at 350 Hz. Now since there is a passive crossover at 375 Hz rolling off the mids, then you should not double up with an active crossover. However many do advise using and active high pass at 70 Hz 24 db. per octave to better protect the mids. This is well below the mids passive roll off and will not affect the audible response.

The bass section requires a 24 db. per octave low pass filter at 350 Hz.

Now one other caveat here. I would use the two NAD amps, as it is likely they will have an identical phase response in respect of the input and output signals.
I would not use that Dynaco ST 70 tube amp. That has an output transformer and I can be certain that it will have a different phase response versus the NAD amps. So that would lead to bad results combined with a NAD amp.

It is pretty clear to me from your rambling post that your thoughts are far from clear.

I have given you the absolute correct information. I was around back then. I also know what I'm doing and I'm not convinced you do. So I am going to tell you straight up, I am not going to get into any lengthy arguments with you.

I have told you exactly and precisely how to set this up, and now it is up to you to implement it.
You also have the wrong crossover point for my speakers, that is probably for Type Aiii's, so you may have been around then, but you left your eyeglasses in the 70's too, apparently, ugh. I can fix amp phase and polarity with this DSP, too, also by following detailed instructions from Snell, so you are (seem) an expert in being wrong about everything maybe, priceless trolling though.
 
TLS Guy

TLS Guy

Seriously, I have no life.
You also have the wrong crossover point for my speakers, that is probably for Type Aiii's, so you may have been around then, but you left your eyeglasses in the 70's too, apparently, ugh. I can fix amp phase and polarity with this DSP, too, also by following detailed instructions from Snell, so you are (seem) an expert in being wrong about everything maybe, priceless trolling though.
Those are Snells specs, although some do low pass 18 db. at 250 Hz. You would have to measure the FR and see which works best. I would add the 70 Hz high pass to those mids. Amps are more powerful, than back then and if you blow a driver a replacement will be hard to find. You are correct to keep the passive crossovers. You could correct phase with DSP, but why add the complication?
 
Emerald_Metaphor

Emerald_Metaphor

Audiophyte
Well, it worked great for a bit, then the left bass dropped out completely, sigh. I am trying another interconnects to the left speaker DAC to DSP connection, but hope I didn't blow the fuse. Nothing visible or audible "burst", or smoked, it just worked, then it didn't, ugh. What I am still unsure of is I have 3 different level/gain controls in the app. There are the input signal percentage sliders, which I have all at 100%. There is another set of sliders for each of the 4 outputs, these were at their 0.0 dB max too. I have the master volume in the app at 0db, and then I carefully turned up my preamp, this worked fine, no signs of trouble, until, left woofer no workie. Any ideas, and thanks for this! I never went past 1/2 from my preamp, and the extra volume was there to start. I hope I have doen something stupdi here, if so let me know. The hardest info to find concerns setting all these various gains, all I find are instruction for car amps mostly. I did start with those channel slider mid way, but than had to turn them up to even get volume, same with the master volume, I started middle, then put my preamp about 40% until the DSP connected, and adjusted from there, sure worked to start, off to try a different interconnect, I did hear so loss as I was moving the unit into what I hoped was its fixed palce, so maybe this extra interconnect, one I haven't used in a while has failed, but if not this, back to normal mode, sigh.
 
Emerald_Metaphor

Emerald_Metaphor

Audiophyte
Sure, lol, kinda in the stressful newbie poop here, had the DAC to DSP interconnect fail in use, typical nonsense, I had two spare sets of these fancy gold plated, well insulated interconnects, apparently this one failed pulling it off, just like the other one did, but this time it didn't fall completely apart, so I just lost 1/2 the signal from DAC to input one on the DSP and didn't know it had failed (I had worse issues with the used analog Rane i tried first, thing was eating the bass signal, so that worried me, seemed a similar problem, but was not in the end).

IT FINALLY WORKS AND THE IMROVEMENT (change?) IS SIGNIFICANT, at worst I have my DSP output gains to the amps a bit low, for not blowing things up sake, until I can find a real human to check my work, Here comes Crime of the Century, monster dynamics thru these Snells! First time ever I've had to adjust volume mid-track for a playing song is with these Snells passively biamped, not a movie, WOW, again thanks.

The bass is so much tighter and detailed, you kinda miss the boom, lol, but my sub is back in play now too (separate though, just a powered sub on the B posts right now, hi impedance inputs, cross wired to both amps to combine the left and right, but I want a second cheap JBL 100 watt sub like this, with 4 unused outputs maybe I can add the subs too (switch to RCA inputs from the DSP, should help the sub's amps too I'd bet) reasoned this was fine for the amps as it is just clipping off a tiny signal, the mosfet amp does the rest, very stable now, app keeps disconnecting, but my USB is flakey as poop, but power light is staying on on the DSP, finger crossed, no extra heat, my amps barely ever run hot, a possible victory, now some Nils Frahm hi-res is giving me chills, wow, wow, wow, the sound is so damn forward now too, awesome!!! Holy truck the bass on this Frahm is clearly better, one of my favs, oh I have never heard that before, wowowowowowoowowo, lol.

Those are Snells specs, although some do low pass 18 db. at 250 Hz. You would have to measure the FR and see which works best. I would add the 70 Hz high pass to those mids. Amps are more powerful, than back then and if you blow a driver a replacement will be hard to find. You are correct to keep the passive crossovers. You could correct phase with DSP, but why add the complication?
Oh ya, that was always part of my plan, as I read in a review you could basically full spectrum the mid-hi, but Snells older instructions do recommend a hipass at 69 Hz, the review said 70 Hz, the thing I find terrifing is moving off what finally works right now, I need some other ears in here to assess the need to EQ, or otherwise tweak, listen to the full passive set up, then the 1/2 active one, but I like what I am hearing, it is much brighter (so maybe some eqing is due), but more revealing for that. My floor is tile, really boomy until I put some small matts and then some rubber stoppers to put some damping between the cabinets and mats. That cut the boom, with the active crossovers all the residual muddiness has gone, and there is clearly more gain free, even with the levels not up full on the DSP, for now I have the channel output levels down a bit, and the master volume at 0 db, leaves me right in my preamps sweet spot. The bass passive crossover is not in play, and but for the stupid Murphy guy, clearly working better!!! Take that 3dB of effective doubling of power straight to the sound quality bank man!!!

I don't have these Snells close to the wall, but will try that too soon, I am instead using the golden ratio method and a very tight Nerd triangle, I sit only 4-5 feet away, inside the soundstage, suprised how well these giants work in this awful square and poorly damped room, I hope to move back into a damped rectangle soon, lol. I bought them because my ported Energy towers died in this room, so did my now sold down-firing sub, the room is 50% of the struggle. The actively configured Snells have declared VICTORY!!!
 
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