I have the sense that at least some of the Jolida specs are subject to continual change/improvement. :-)
I recently received a JD302brc, which (surprise!) arrived with a bypass switch as well as XLR inputs...neither of which show up in the photos of the product on their site, or even in the manual that they shipped with the amp.
It's a rare case of me getting more than I expected!
It also has two sets of pre-outs, fixed and variable. Or at least mine does...
Realremo - is your question about the pre-outs because you want to be able to connect the Jolida to a subwoofer in your 2.1 system?
If so, another option, and one that is preferred by a good many subwoofer manufacturers, is to connect the speaker terminals on the amp to high-level inputs on the subwoofer, rather than go from line-level outputs on the amp to corresponding inputs on the sub.
Sorry if that's not pertinent to your question but your mention of wanting to run a 2.1 system made me think it might be.
Sfar, so I can connect both the speaker wires and wires for the sub to the same speaker terminals without hindering the sound? The jolida only has a single pair of speaker terminals.
I have read that the high-level connection gives you better synching between the sub and the speakers for music.
I was also thinking about high-passing my bookshelf speakers through the powered sub, but this requires a main-amp-in connection on the amp, very few integrateds have these.
Interesting that Soundgasm got more than he expected! I guess Jolida, the company itself, is the only authority on what exactly their back panels look like, but their responsiveness is as sparse as their website...
Jolida 1501RC has better looks than the NAD line, but I would lose the ability to high-pass my bookshelf speakers...
Realremo - yes, that's exactly the way to do it if you want to use the high-level inputs on the sub and have only one set of speaker terminals. I used that kind of connection on an HSU sub, at HSU's recommendation, and am doing the same on a Mirage sub now.
As HSU explained it to me, with a powered sub all that's coming from the speaker terminal connections on the amp to the sub is frequency and amplitude information, very little current is actually moving through the cables and it has no effect on the signal going to the main speakers. They said, in fact, that you don't even need the same gauge or quality of speaker wires as are going from the amp to your main speakers.
On my amp with five-way binding posts I connected the main speaker cables with spades and used bananas plugged into the ends of the terminals for cables going to the sub. I tried the setup with both the high and low-level connections to the sub and found it much easier to integrate the sub using the high-level connections, even without the ability to high-pass the speakers.
Realremo, the second amp I owned was the Jolida 1501A. I don't recall it having preamp outputs, though that could have changed since then. I ran a Velodyne sub using speaker level connections. It was that bad experience that sent me on a decade of wanting/buying full range floorstanding speakers. Fortunately, I took a chance on M&K reference monitors + sub + bass management controller and now I'm sold on the notion of monitor/sub systems.
If you have true full range speakers, then speaker level or line level (without high-passing the mains), could yield a smoother bass response because of the multiple bass sources. If you have smaller speakers, my advice is to always take the bass load off the speaker by high-passing them. There's no reason that I know of that makes integrating a subwoofer any easier with either connection method.
A word about the Jolida 1501A... I really loved the sound of that amp. It had a sound. At that point in my listening experience it was the perfect product -- adequate power, nice "musical" sound, very reasonable price. Based on where I am today, I'd take a NAD, Rotel, Bryston, etc.over Jolida any day of the week simpy due to the loss of detail. The Jolida makes everything sound nice and nothing sound like it is.
Bob_reynolds, what about high-passing the speakers using the speaker terminals on the powered sub? If the sub has two pairs of terminals, the signal goes through these terminals and then out to the speakers - certainly some subs out there have active crossovers at the terminals going out to the speakers. Not all subs have low-level RCA outputs back to the amp. If I try to high-pass the speakers using these terminals, what powers the 2 speakers - the amp in the NAD or the amp in the powered sub? Are there any disadvantages in this technique?
Also - what do you think of HSU's line of subs? Do they have any that would fit your crossover criteria?
Realremo, I believe there are some external passive speaker level high pass filters around (ACI had them I think). Yes, you are correct that some powered subs do filter the speaker level connections. My guess is that they are passive due to the signal level.
Many powered subs do not provide bass management. They expect, rightly so I guess, that that'll be taken care of in another component.
You raise a question I've never thought about before -- using speaker level connections through the sub to the main speakers. I've read that the impedance on the speaker level inputs is usually quite high (maybe 100K ohms) so as not to load the power amp. So what impedance does the power amp see if the sub's output speaker connections go to the main speakers? I don't know. Maybe those with output connecitons don't present a high impedance; maybe they reflect the impedance of the main speakers. I'm pretty sure that the sub's amp is only driving its woofer.
I think HSU makes an excellent product; though I've never owned one. I don't think any HSU sub has builtin bass management. They offer a rather expensive external crossover (I like the NHT X2 filter). I'm a fan of SVS -- I've had very good communications with their tech support person and they build in the US.
Bob - I like SVS because their crossover point is 80Hz going back to the amp. Other subs that I have looked at (Velodyne DEQ series, for example) crossover at 120Hz back to the amp. I want the 685s working as hard as possible, so I think a lower crossover point is more desirable...agree?
SVS does not show their frequency ranges like other sites, they don't use the typical "+/- 3dB" spec. Can you decode this graph they have on their site:
It seems to me that the SVS PB10-NBS produces deeper bass and is much heavier construction than other subs at the same price point.
Thanks! SVS should give you some free stuff, you are such a proponent of theirs on A-gon.
Can you decode this graph they have on their site?
Looks like everything from about 22Hz to 400Hz is flat to within +/- 1.5db, for sound pressure levels of a little over 90db. The graph says nothing about distortion, though.
You raise a question I've never thought about before -- using speaker level connections through the sub to the main speakers. I've read that the impedance on the speaker level inputs is usually quite high (maybe 100K ohms) so as not to load the power amp. So what impedance does the power amp see if the sub's output speaker connections go to the main speakers?
A lot of subs that have both speaker in and speaker out terminals are providing them just to facilitate convenient connections. In those cases the two sets of terminals are simply wired together, with wires branched off internally from those points to carry the signals to the sub's amplifier (which as you indicated presumably has a very high input impedance). So the main amp would see the impedance of the main speakers, essentially directly.
A few subs, such as certain Definitive Technology models, have the speaker-level outputs high-passed (in their particular models generally at a fixed 80Hz frequency). I have no particular familiarity with those models, but it would stand to reason that the high-pass filter is passive (perhaps being as simple as a capacitor in series). In which case the main power amp would see the impedance of the main speakers at frequencies significantly above 80Hz, and would see a very high impedance at frequencies significantly below 80Hz.
However, that approach would certainly not seem like a recipe for good sound. Frequency response irregularities would be introduced if the impedance of the main speaker were not perfectly flat throughout the crossover region (which would be pretty wide if the high-pass filter were just a capacitor in series). Bass damping for the main speakers would be degraded by the increase in the source impedance that is driving it. The crossover element(s) itself would introduce its own non-idealities into the signal path, potentially affecting any and all frequencies up through the treble. And the high-pass crossover frequency would probably vary considerably from the 80Hz depending on how different the main speaker's impedance around that frequency is from 8 ohms or whatever main speaker impedance the sub's designer assumed it would be working into.
Al, Realremo: here's a link to a set of measurments for the SVS 10" ISD (said to be identical to the newer NSD) subwoofer: http://www.hometheatershack.com/forums/subwoofer-tests-archived/994-svs-pb10-isd-2nd-unit.html
And here's the 12" version: http://www.hometheatershack.com/forums/subwoofer-tests-archived/8151-svs-pb12-nsd-2-a.html
And the index: http://www.hometheatershack.com/forums/subwoofer-tests-archived/6015-index-subwoofer-tests-manufacturer-model.html
Al: thanks for the analysis of the impact of a passive speaker level filter. I don't know that the increase in bass damping of the main speakers would be much of an issue since you are wanting to remove the bass from them anyway. But, I guess you are saying that the bass they would still produce would not be as well controlled as without the passive filter. The last sentence of your last paragraph is very important. I had not considered that aspect at all.
Realremo: I had to buy my SB12-Plus just like everyone else. No free stuff from SVS for Bob. Seriously, if you have any questions about SVS products contact Ed Mullen (?? as I recall). Very knowledgeable fellow and more than willing to share. I believe Ed did some reviewing before joining SVS (http://www.hometheaterhifi.com/volume_13_1/svs-pb12-plus-subwoofer-1-2006-part-1.html
I don't know that the increase in bass damping of the main speakers would be much of an issue since you are wanting to remove the bass from them anyway. But, I guess you are saying that the bass they would still produce would not be as well controlled as without the passive filter.
Yes, exactly. And with an 80Hz high-pass, that conceivably could even be first-order (6db/octave rolloff), bass damping and back-emf control would still likely be a very significant consideration.
OK Almarg - so high-passing speakers is bad all around, or just high-passing them through the speaker terminals (passive crossover) is bad? What about high-passing through an active crossover, either on board the sub or through a separate component? I am a wee bit lost in all the very interesting technical terms. Thanks!
Realremo -- The issues I cited apply only to high-passing at speaker level through a passive high-pass filter (which most subs do NOT do).
The high-pass filters that many subs have, which output line-level signals via rca connectors, do not have any of those issues, nor would an external active crossover. And if there are any subs that drive their high-passed speaker-level outputs from a power amplifier internal to the sub, those issues would be inapplicable to them as well.