Hi,
i am running 802 nautilus with krell fpb600, with krell krc-hr preamp and accustic arts dac2 mk4 dac. now the sound it very good and i want to add diy subwoofer at around 80hz but do not want to alter the above chain . so i need help regarding how to add lets say a good capacitor in series with the bass drivers of nautilus 802 to restrict output above 80 hz.
regards
i am running 802 nautilus with krell fpb600, with krell krc-hr preamp and accustic arts dac2 mk4 dac. now the sound it very good and i want to add diy subwoofer at around 80hz but do not want to alter the above chain . so i need help regarding how to add lets say a good capacitor in series with the bass drivers of nautilus 802 to restrict output above 80 hz.
regards
The nautilus is tuned to 21hz already!
To answer the question, it appears that it is about 4 ohms, so to knock it off around 80hz you'd need about 500 mfd of series capacitance on it.
How much are you looking to spend on capacitors?
To answer the question, it appears that it is about 4 ohms, so to knock it off around 80hz you'd need about 500 mfd of series capacitance on it.
How much are you looking to spend on capacitors?
Hi,
You want to add a diy sub and restrict them to 80Hz ? Are you serious ?
No way IMHO would this ever improve anything, they don't need subs.
But if you really want monstrous low bass levels, decrease the input
coupling caps of the power amps for some bass roll off and run the
extra subs in parallel, both amps driven from the preamp.
Cannot see it sounding any better though, personally if bass is not
up to scratch I'd build some bass boost into the amplification chain.
rgds, sreten.
Series large electrolytics for vented boxes are a very bad idea.
You want to add a diy sub and restrict them to 80Hz ? Are you serious ?
No way IMHO would this ever improve anything, they don't need subs.
But if you really want monstrous low bass levels, decrease the input
coupling caps of the power amps for some bass roll off and run the
extra subs in parallel, both amps driven from the preamp.
Cannot see it sounding any better though, personally if bass is not
up to scratch I'd build some bass boost into the amplification chain.
rgds, sreten.
Series large electrolytics for vented boxes are a very bad idea.
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I'm with Sreten, the Nautilus should already have solid response down to 21hz or so, according to it's tuning, and should be very easily able to do so driven with a Krell FPB 600. It's possible that having the Nautilus out in the room (out of the corners) causes a slight roll off. You might be able to leave them connected directly without caps and simply add subwoofers rolled off at whatever frequency the placement of the Nautilus is causing it to lose efficiency. You might have to experament, but you'll probably find that a couple of big subs playing from 20-ish up to about 40 hz or so might add just enough low end "ease" to be nice sounding.
I'd build a couple of good subs which you should be able to power with the same Krell without issue, slap a 16mh coil on them in series and give it a shot.
Maybe I'm crazy!
As far as output coupling caps, I'm not sure if I'd want to mess with a Krell! That's just me though.
I'd build a couple of good subs which you should be able to power with the same Krell without issue, slap a 16mh coil on them in series and give it a shot.
Maybe I'm crazy!
As far as output coupling caps, I'm not sure if I'd want to mess with a Krell! That's just me though.
ok . lets rewind it. thnaks for the input though but 802 lacks the heart thumping bass below 40 and relieving the 802 below 80 would make mid bass clear.
Now the fpb is directly connected....NO signal coupling capaitor from input th output....and i dont want any active filter to distorld low level signal as well.....as far as just adding ablow 40 hz subwoofer would colour the bass from tow different drivers...imho
Now the fpb is directly connected....NO signal coupling capaitor from input th output....and i dont want any active filter to distorld low level signal as well.....as far as just adding ablow 40 hz subwoofer would colour the bass from tow different drivers...imho
Well, if you have the means to try it, there's nothing wrong with building a pair of subs and using a simple crossover to give it a try. I would probably go a little lower than 80, though. It's up to you, a passive crossover is easy enough to design for subwoofers.
As you move your speaker, the bass will change. I would add a sub without crossing the 802. The trick will be finding the right location for the sub. Level, phase, and location.
Are you assuming that a passive crossover is transparent, while any kind of active crossover is going to distort and mess up the signal? Have you actually tested this idea?
It appears to me that your choices here mean that you give up the chance to improve things dramatically in order to avoid something at the limits of audibility.
Here's my suggestion. Put an active high pass on the mains at a point determined by where you stop getting "value" out of using the 802 bass. It probably will help smooth in-room response. Probably around 40 - 60 Hz. Then bring in the sub and again base the low pass point on where the response of the sub is useful. It can also smooth things out. I find that the end result of a good integration is far more significant than any imagined loss of fidelity with an active crossover.
A digital active also lets you shape the bass response, while a sub or a number of them also can give the firepower behind it.
That "heart thumping bass" you refer to will actually be around 70-120Hz. 😉
I'd add a vote for active crossover or modification to the amp for active filtering.
Its difficult to get a smooth passive crossover for a vented box. The double impedance hump will give you messy response at the rolloff frequency. This won't help the blend to your subwoofer.
Sealed box highpass filters can be better and there is a class of 3rd order system that uses the series cap to flatten the response.
Go active.
Its difficult to get a smooth passive crossover for a vented box. The double impedance hump will give you messy response at the rolloff frequency. This won't help the blend to your subwoofer.
Sealed box highpass filters can be better and there is a class of 3rd order system that uses the series cap to flatten the response.
Go active.
Taking a soldering gun to a Krell FPB600 would make my skin crawl. Nearly $100,000 USD of 2 channel gear, I'd lean more toward getting another amplifier.
One of the big Crowns would probably be good, with active crossovers built in already to power the subs. I'm with Allen, pick a crossover point to augment what's already there or hang a couple of 250mfd fast caps strapped together off the back of the nautilus' positive terminal if you wanna clean em up and then pick a higher crossover point.
DrDyna, modifying amps in this way is usually an opportunity to ditch an electrolytic capacitor being run full range, for something better (for whatever that may be worth), without adding any active stages. By the way this amp is full of them.
Totally agreed with all above. now i really want thant thump which 802 with even krell fpb-600 cannot provide. but please look at the low level chain, acustic arts dac2 mk4 DAC, krell krc-hr pre amp and then the power amp al fully balanced end to end...... where , how and of what quality rossover should i put in.... i susupect adding anything no matter of what quality on the low level signal line will definitely alter the sound...mid+high.... so i want to go with passive mod to 802 as high pass filter. the following could be options
1. add acapacitor in series with bass drivers....not very good idea i suppose i would be a large capacitor,,,,,,,quite some physical vibration there...
2. block the bass drivers firing port.... would shift the tunning frequeny up making it sealed and more gradual but early roll off ....may be around 80 hz
3. custom build heart thumping twin 2x10inch b&W drivers from 800 series with separate amp electronically filtered to cover 120-40 hz
4. 2 pairs of 15 inch asw855 b&W drivers in isobaric pull push configuration in sealed chambers with dsp control and some1000+1000 w for each channel for bass boost equalizzation at around 20 hz////..
seeems asking too much,,,,, but lets at least start thinking.
;-)
1. add acapacitor in series with bass drivers....not very good idea i suppose i would be a large capacitor,,,,,,,quite some physical vibration there...
2. block the bass drivers firing port.... would shift the tunning frequeny up making it sealed and more gradual but early roll off ....may be around 80 hz
3. custom build heart thumping twin 2x10inch b&W drivers from 800 series with separate amp electronically filtered to cover 120-40 hz
4. 2 pairs of 15 inch asw855 b&W drivers in isobaric pull push configuration in sealed chambers with dsp control and some1000+1000 w for each channel for bass boost equalizzation at around 20 hz////..
seeems asking too much,,,,, but lets at least start thinking.
;-)
Yes, but wouldn't that mean that you'd now have a Krell amplifier that was permanently unable to be used below the crossover frequency?
Edit: and most certainly void it's warranty?
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With the old b&w matrix series you got two different foam plugs for the port to tune the lows to the room or subwoofer. One plug was open cell foam and the other allmost air tight.
You could do something similar, stuff the vent with something to make it behave like a sealed box, making it simpler to get a smooth transition to the subwoofers with no crossover on the 802`s.
You could do something similar, stuff the vent with something to make it behave like a sealed box, making it simpler to get a smooth transition to the subwoofers with no crossover on the 802`s.
Yes, it would be large, probably 2 or 3 big caps twisted together. I wouldn't worry about vibration too much, I've had passive sub crossovers for about 15 years and I've never heard a capacitor rattling.
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