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Weird biamp experience

#21
Wait a minute... did you remove the passive crossovers (wiring) from the speakers OR are you driving the individual speakers with the passive crossovers still connected.

If the latter, you have all kinds of illegal loading of the amp because of the way passive crossovers work and you are lucky that your amp didn't go up in a cloud of magic smoke.
 
#22
OK, here's what I got from the OP's posts, for what it's worth - not much since I'm not him, so feel free to disregard until further clarification - just going out on a limb here.
The Trace head (can't be arsed to look for the manual on the internet, assuming it's even there somewhere, sorry) has an active crossover but probably just one power amp: to use it to itself power either the lows or the highs you have to patch one of the xovered outs back to the FX return (or maybe not, as I said I don't know specifically and I was probably busy playing with LEGO bricks when stuff like this first came out); however, I suspect Triad is not doing it, but instead sending both signals to the two sides of the IPR, thus using the Trace only as a pre and crossover. Either way, two amplified signals, one de-feminated (bottom to 250 Hz) the other emasculated (nada lows, just everything else from 250 Hz up), are sent to each of the pair of identical passive cabs, which happen to be 3-way PA speakers, of course with internal crossovers, but, again I suspect, themselves not bi-amp capable, but only provided with one full-range input each (or with a couple each, parallel, for daisychaining). Also, I previously assumed, and the OP didn't correct me, that said passive crossovers are unmolested, or at least he didn't touch them.
[Not different from what they did in the Eighties, with dubious results: two cabs - let's assume they're identical 4x10s, for the sake of argument - fed amplified signals, one is lows, the other highs. Do the cabs happen to have tweeters? Then of course one of them is there just to plug the hole in the baffle, not really doing squat with this configuration; similarly, the woofers of the high cab don't do the heavy lifting.]
Now, if the 250 Hz selected back at the Trace head is lower than the frequency of the woofer-to-midrange part of the internal passive crossover (assuming the woofer is LP'd at all), even the woofer in the "high" cab is indeed working albeit less than the other one, reproducing the signal from 250 to where it taps out).
Still, why does Triad not experience a loss of volume with this setup? and why the perceived improvement in quality?
 
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#23
HaphAsSard said:
OK, here's what I got from the OP's posts, for what it's worth - not much since I'm not him, so feel free to disregard until further clarification - just going out on a limb here.
The Trace head (can't be arsed to look for the manual on the internet, assuming it's even there somewhere, sorry) has an active crossover but probably just one power amp: to use it to itself power either the lows or the highs you have to patch one of the xovered outs back to the FX return (or maybe not, as I said I don't know specifically and I was probably busy playing with LEGO bricks when stuff like this first came out); however, I suspect Triad is not doing it, but instead sending both signals to the two sides of the IPR, thus using the Trace only as a pre and crossover. Either way, two amplified signals, one de-feminated (bottom to 250 Hz) the other emasculated (nada lows, just everything else from 250 Hz up), are sent to each of the pair of identical passive cabs, which happen to be 3-way PA speakers, of course with internal crossovers, but, again I suspect, themselves not bi-amp capable, but only provided with one full-range input each (or with a couple each, parallel, for daisychaining). Also, I previously assumed, and the OP didn't correct me, that said passive crossovers are unmolested, or at least he didn't touch them.
[Not different from what they did in the Eighties, with dubious results: two cabs - let's assume they're identical 4x10s, for the sake of argument - fed amplified signals, one is lows, the other highs. Do the cabs happen to have tweeters? Then of course one of them is there just to plug the hole in the baffle, not really doing squat with this configuration; similarly, the woofers of the high cab don't do the heavy lifting.]
Now, if the 250 Hz selected back at the Trace head is lower than the frequency of the woofer-to-midrange part of the internal passive crossover (assuming the woofer is LP'd at all), even the woofer in the "high" cab is indeed working albeit less than the other one, reproducing the signal from 250 to where it taps out).
Still, why does Triad not experience a loss of volume with this setup? and why the perceived improvement in quality?
Click to expand...
exactly what I got out of OP. My guess is the Trace cross is set up higher than the 250hz lower limit, but even if it wasn't that would still be a good bit of the bass going to both woofers.
 
#24
Uh, looks like I was risking to fry the Peavey? The cabs are unmodified, still have the original 3 way crossover inside. The Trace GP12X is a preamp only, not a "head", and it's wired to the Peavey IPR. The crossover cut was set at 250hz but at this point as AgedHorse says, I must only be thankful 'cause the Peavey didn't broke! No idea why the filtered signal should ruin the amp when going into another filter but if he says so, I'm definitely not going to try again for sure!
 
#25
Think I'm starting to grasp the situation. Help me out in one regard: what's the model # of the H&K 3-way enclosures? A close-up pic of the back panel would be useful, as well.

I have similar Carvins and am able to biamp with all crossovers physically present but with one removed from the path.

Riis
 
#26
They're very old... to the point that when I mailed H&K to know the specs, they told me "Sorry man, they're too old and we have no documentation on items of that age" LOL.
I'll try to take a picture of the back panel asap.
 
#27
Triad said:
They're very old... to the point that when I mailed H&K to know the specs, they told me "Sorry man, they're too old and we have no documentation on items of that age" LOL.
I'll try to take a picture of the back panel asap.
Click to expand...

Okay...I'll review when I get home this evening. What's really neat is the fact you have a choice (...I believe) of two crossover resources in addition to the enclosure's onboard passive circuit: the Trace and the IPR. I really need to review the manual on the IPR.

Riis
 
#28
Thanks! Is there anything I can have done (by a tech) to "upgrade" and update the Trace preamp? I'm not going to sell it so if there's something easy and not madly expensive that can be done to make it "better"... I'm open to suggestions.
 
#29
Triad said:
The Trace GP12X is a preamp only, not a "head", and it's wired to the Peavey IPR.
Click to expand...
Oops, I got the impression it was a head from one of the posts above (not one of yours) but in retrospect I just assumed it without even considering the possibility it was a preamp.
The cabs are unmodified, still have the original 3 way crossover inside.
Click to expand...
And to be clear once and for all (unless or until you post a picture of the panel): does each of the cabs have separate inputs for bi-amping or only full-range ones?
Uh, looks like I was risking to fry the Peavey? (...) The crossover cut was set at 250hz but at this point as AgedHorse says, I must only be thankful 'cause the Peavey didn't broke! No idea why the filtered signal should ruin the amp when going into another filter but if he says so, I'm definitely not going to try again for sure!
Click to expand...
I think the danger @agedhorse alluded to is only if you connect two or more drivers in the cab (woofer, midrange, tweeter) each to a separate power amp without bypassing the internal passive crossover, which would put everything in the (wider) circuit at risk including the amps, but unless I'm mistaken you didn't. There's no danger that I'm aware of in feeding a passive crossover with a (one) signal whose bandwidth has been narrowed upstream.
Downunderwonder said:
exactly what I got out of OP. My guess is the Trace cross is set up higher than the 250hz lower limit, but even if it wasn't that would still be a good bit of the bass going to both woofers.
Click to expand...
But not overlapping, right? The woofers in each cab are taking care of different slices of the low department, unless I'm getting all this wrong (or unless we refer to the fact an analog crossover has slopes and overlap in the crossing region).
Zooberwerx said:
What's really neat is the fact you have a choice (...I believe) of two crossover resources in addition to the enclosure's onboard passive circuit: the Trace and the IPR. I really need to review the manual on the IPR.
Click to expand...
Per a cursory gander at the manual, the IPR has "100 Hz switchable 2nd order High pass and 3rd order Low Pass per channel".
 
#30
No biamp inputs on these cabs... only full-range inputs. The crossover frequency was definitely set at 250hz... I double-checked. Could be interesting to move it up and see how the stack sounds. Heck, I could even record a video! :D
 
#31
I think what Agedhorse was getting at was the possibility of you having custom tapped onto the woofers with your amps but leaving the cab crossovers intact. Smoke city for amps without magic shutdown protection circuitry.

For an experiment turn on only the ''high'' channel, then only the low channel.
 
#32
Well, for now I'm using both speakers full-range in "stereo" using the signal-thru of the Peavey from A channel to B 'cause the Trace only has one mono full-range output. Sounds great.
 
#34
No, it has ONE MONO full-range output (so it doesn't work with stereo Y cables) and two lows/highs outputs for the biamp with adjustable crossover frequency.
Now that I'm using it full-range, I'm using the single output and then send the signal to the channel B of the power amp directly from the channel A.
 

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