Hello, I’m planing to convert my system to be active.
My current system:
CD tranporter —> Integrated amp with built-in DAC —> Speakers.
The active system:
CD tranporter —> Integrated amp with built-in DAC —> Active crossover —> Power amp —> Speakers.
Since my integrated amplifier has no pre-out/main-in channels, I need to use speaker outputs to feed signal to the active crossover instead. According to the attached spec of the active crossover, there are four “high-level” inputs with impedance in each channel of 10-10k Ohms, my questions are whether the 10-10k Ohms is the impedance load presented to integrated amplifier? If yes, should I connect all four inputs or simply connect only two channels, the amplifier is two channels stereo? To my understanding, connecting all four inputs will halve the impedance i.e. 10-10k to 5-5k Ohms on each channel, am I correct? Last question, the integrated amplifier is rated at 100 Wpc, will it detrimental to the electronic crossover?
My current system:
CD tranporter —> Integrated amp with built-in DAC —> Speakers.
The active system:
CD tranporter —> Integrated amp with built-in DAC —> Active crossover —> Power amp —> Speakers.
Since my integrated amplifier has no pre-out/main-in channels, I need to use speaker outputs to feed signal to the active crossover instead. According to the attached spec of the active crossover, there are four “high-level” inputs with impedance in each channel of 10-10k Ohms, my questions are whether the 10-10k Ohms is the impedance load presented to integrated amplifier? If yes, should I connect all four inputs or simply connect only two channels, the amplifier is two channels stereo? To my understanding, connecting all four inputs will halve the impedance i.e. 10-10k to 5-5k Ohms on each channel, am I correct? Last question, the integrated amplifier is rated at 100 Wpc, will it detrimental to the electronic crossover?
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You could perhaps tap at the Volume pot.
Put some resistors say 470-1K 2-3W in series with the crossover inputs or You'll fry it.
That actually won't do a thing. The maximum output voltage of a 100W amp is around 28V, or around 30dB higher than 0dBV. So...you might need an attenuator. How much attenuation? Need the full specs on your crossover first, a make/model would be nice. The posted specs make no sense. But in general, you only need to drive one pair of its inputs, not all of them.
The crossover is a/d/s/ 642ix. And the integrated amp is Sansui AU-X911DG.
Thanks so much
Ok, thanks for the information. So, we need to talk about what you're trying to do here. Clearly, an improvement is desired. Since your speakers obviously have internal crossovers that were designed specifically for them, we need to ask what you think you're improving with the external crossover and bi-amping. A common assumption is that there's an advantage to directly powering drivers with a power amp, which is not specifically true. Also, there is a general assumption that an external, active crossover would somehow do a "better job" than the ones built into the speakers. Also, not specifically true.
The speakers, with their drivers, enclosuer, and crossover were designed as a system (assuming they are of any reasonable quality to begin with). As such, at least some care was taken in engineering the type of crossover included. It's actually a fair part of the voicing of the speaker. When you change the crossover, either internally, or rewire for bi-amping and an external crossover, you are radically altering the overall design and performance of the speaker. This is a case where there are infinite wrongs, but very few rights. The rights are found by research, design, testing, adjusting, etc. If you plan to do all of that, great. But just swapping to an active crossover and changing the speakers to bi-amping is not likely to net you an improvement just because of what you did. You will embark on the path to research, design, testing, tuning, etc, in some way, even if it's just listening and adjusting. I never recommend going to an active crossover with bi-amped speakers unless the user is planning to learn a lot about measurement first.
The crossover you're trying to use was designed for the mobile market. It is missing nearly every control that would make tuning an active crossover possible. The frequency and slope of the crossover filters are fixed by "modules" that apparently are swappable, but not tuneable. In the world of optimizing active crossovers, this is like having two hands tied behind your back while blindfolded, in that the chances of any of the pre-set curves and tunings being right are minimal at best.
The next problem is interfacing your integrated amp to the crossover. The mobile crossover was intended to work with a "head unit", probably of limited power (since it assumes power amps follow the crossover). While power is not the problem here, the output voltage of your amp will be. The maximum output voltage from a head unit, with no external power amp, will likely be around 9 or 10 volts (rms), differential. Your 100W integrated will produce around 28Vrms, single-ended. To get that to play well with the crossover you need to first adjust the balanced input controls to their minimum setting. This may be adequate, but it might still be possible for your integrated amp to over-drive the crossover. You'll just have to try it, you will not blow anything up doing so. But if you get distortion from the crossover, you'll need to pad the crossover's input by around 10dB so the crossover input doesn't clip.
So, set things up like this:
1. Turn the crossover input level controls fully counter-clockwise.
2. Connect your Integrated amp to the two balanced inputs of the crossover
3. Connect your power amps to the appropriate outputs, turn their input controls all the way down.
4. Turn the volume control on your Integrated amp all the way down
5. Turn on the Integrated amp
6. Turn on the crossover, and wait 10 seconds or so
7. Turn on the power amps.
8. Play a CD and turn up the Integrated amp's volume control to a position that you would exect a comfortable listening level (it may not be right yet, and you may hear nothing).
9. Slowly turn up the input level controls on the power amps until you hear music at a volume level that matches what you would expect from your Integrated amp's volume control position.
10. Adjust the amps driving the tweeters and woofers for reasonably balanced bass and treble.
11. Turn up your Integrated Amp's volume control and see if you can get good clean sound without distortion and an adequately loud level. If so, you're done. If not, and you get distortion before it's loud enough, you have a decision to make.
12. To get more volume without distortion, turn down your Integrated amp and turn up our power amps.
13. Alternative: to get more volume without distortion, install a 10dB pad in before each crossover input, and turn up your power amps to compensate.
As I said, I do not recommend this project without also learning acoustic measurement, but people leap of cliffs all the time, so can't stop you. At least follow the suggestions, and if you still need help, post here.
The speakers, with their drivers, enclosuer, and crossover were designed as a system (assuming they are of any reasonable quality to begin with). As such, at least some care was taken in engineering the type of crossover included. It's actually a fair part of the voicing of the speaker. When you change the crossover, either internally, or rewire for bi-amping and an external crossover, you are radically altering the overall design and performance of the speaker. This is a case where there are infinite wrongs, but very few rights. The rights are found by research, design, testing, adjusting, etc. If you plan to do all of that, great. But just swapping to an active crossover and changing the speakers to bi-amping is not likely to net you an improvement just because of what you did. You will embark on the path to research, design, testing, tuning, etc, in some way, even if it's just listening and adjusting. I never recommend going to an active crossover with bi-amped speakers unless the user is planning to learn a lot about measurement first.
The crossover you're trying to use was designed for the mobile market. It is missing nearly every control that would make tuning an active crossover possible. The frequency and slope of the crossover filters are fixed by "modules" that apparently are swappable, but not tuneable. In the world of optimizing active crossovers, this is like having two hands tied behind your back while blindfolded, in that the chances of any of the pre-set curves and tunings being right are minimal at best.
The next problem is interfacing your integrated amp to the crossover. The mobile crossover was intended to work with a "head unit", probably of limited power (since it assumes power amps follow the crossover). While power is not the problem here, the output voltage of your amp will be. The maximum output voltage from a head unit, with no external power amp, will likely be around 9 or 10 volts (rms), differential. Your 100W integrated will produce around 28Vrms, single-ended. To get that to play well with the crossover you need to first adjust the balanced input controls to their minimum setting. This may be adequate, but it might still be possible for your integrated amp to over-drive the crossover. You'll just have to try it, you will not blow anything up doing so. But if you get distortion from the crossover, you'll need to pad the crossover's input by around 10dB so the crossover input doesn't clip.
So, set things up like this:
1. Turn the crossover input level controls fully counter-clockwise.
2. Connect your Integrated amp to the two balanced inputs of the crossover
3. Connect your power amps to the appropriate outputs, turn their input controls all the way down.
4. Turn the volume control on your Integrated amp all the way down
5. Turn on the Integrated amp
6. Turn on the crossover, and wait 10 seconds or so
7. Turn on the power amps.
8. Play a CD and turn up the Integrated amp's volume control to a position that you would exect a comfortable listening level (it may not be right yet, and you may hear nothing).
9. Slowly turn up the input level controls on the power amps until you hear music at a volume level that matches what you would expect from your Integrated amp's volume control position.
10. Adjust the amps driving the tweeters and woofers for reasonably balanced bass and treble.
11. Turn up your Integrated Amp's volume control and see if you can get good clean sound without distortion and an adequately loud level. If so, you're done. If not, and you get distortion before it's loud enough, you have a decision to make.
12. To get more volume without distortion, turn down your Integrated amp and turn up our power amps.
13. Alternative: to get more volume without distortion, install a 10dB pad in before each crossover input, and turn up your power amps to compensate.
As I said, I do not recommend this project without also learning acoustic measurement, but people leap of cliffs all the time, so can't stop you. At least follow the suggestions, and if you still need help, post here.
Nope. The crossover is essentially a 10K briding input. Series resistors won't form a significant pad unless they are huge. 10K series resistors would create only a 6dB pad, so 470 does, effectively, nothing.
Headphone level is probably too low to drive a line input. Figure the 1mW headphone sensitivity as a reference, and that'll give you LOUD headphone volume. 1mW into 30 ohms is 0.17V, but that's typically a loud level, with some headphones at over 100dBSPL for a 1mW input. Line level, at -10dBV is .25V, but that's an average level, not a loud level. So, take 10-15dB off the headphone output to normalize it, and it's too low for line inputs.
Good for you! The 470 ohm resistors had nothing to do with your success though. Your Pioneer happens to have enough level at the headphone jack for the JBL.
Well, 40V into 8 ohms would be a 200W amp, and that's not what he has. Your caluculations are right if the 470 ohm resistors are shorted to ground, but that's not what's happening.
But perhaps I don't understand what the OP is doing. I thought he was attempting this:
CD tranporter —> Integrated amp with built-in DAC —> Active crossover —> Power amp —> Speakers.
The headphone output, or amp output we've been talking about is the Integrated Amp. The Active crossover has a 10K or higher bridging input. There won't be anywhere close to 40V at any point (the amp was rated at 100W, presumably into 8 ohms = 28.28V at full power). There is a pad needed, but the active crossover is "ready" for being fed from a power amp, likely no more than 20W > 4 ohms (it's for the automotive market), and that max voltage is 8.9V, which would be fine with the adjustable inputs on the crossover, as it was designed to do. However, the output of a headphone jack is much lower, and depending on the purpose (or design responsibility preventing hearing damage), it will only do a few mW into 30 ohms, which might be enough, but might not. In either case, series 470 ohm resistors won't have any appreciable current through them because the "load" is the active crossover input, which is 10K+. So, very little current, very little voltage drop, and very little padding as the result.
The output that drives the speakers is another power amp after the crossover.
Or...did I miss something?
Older equipment is typically designed to drive 600 ohm headphones from its headphone amplifier. Voltage will be much higher than contemporary equipment, which is typically designed to drive 32 ohm headphones (some are 16 ohms).
A 120 ohm series resistor was industry standard for decades. Modern headphones intended for portable use are designed to be driven from a very low impedance source, very different from old style headphones that are voiced for 120 ohm source impedance.