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View Full Version : Amp Recommendation and Bi-amping D-130/075



George Beckwith
10-24-2010, 11:59 PM
I am the original owner of a pair of C37 enclosures with D-130, 075, and N2600 inside each.

I am considering purchasing an Onkyo TX-NR708 AV receiver, and have several questions.
1. Is the Onkyo TX-NR708 a reasonable AV receiver to use with my JBLs? If not what’s better?
2. The Onkyo TX-NR708 is capable of bi-amping. I called Onkyo and asked a rep what the crossover frequency is and the rep stated that it would be automatically determined by the Audyssey system. I have several questions on bi-amping. First are the D-130 and 075 capable of being bi-amped with the Onkyo, and secondly is there any advantage to bi-amping over just using the N2600 crossover.

Thanks in advance for your help with this.

lgvenable
10-25-2010, 01:34 AM
George
A couple of recommendations:
first look high and low from theater scrappers/eBay and find a set of mono-tri-amps like AB Systems 713 or 713A's you can get them for ~400ish they do either 250-150-150 (713) or 500-250-250 (713A) into 8 ohm loads.
Or...more expensive but more accurate
buy a pair of BGW 750C for the bottom end, a pair of BGW 250D's for the mids/HF that'll give you all the power you need to drive the 130's and 075's. THe 750's go for 250 to 300 and the 250D's about 150.00 in good shape. Buy from a theater closing or a studio sell off, which is mainly how I acquired mine.

I'm running (front left-right-center) triamped set of LF:2206 mids:2360-2445J HF:2404H with a threesome of the 713, and the sound is stunning. I'vr also used the BGW combo with a dBX Driverack 260 to provide parametric EQ. The AB 713's have the active EQ built in.

Others will give their version thats my 0.02$;)

I'm running 19 BGW amps now, and have to rate their sound as good as a modern Krell amp; but at serious savings. They are even better at LF, once you recap them, which takes about 1 hour per amp.
I'm using an Integra DHC80.1 to drive them (also known as a OnkyoPro PR-SC5507).

FYI the amp or pre-pro of choice to me is one which will allow you to use balanced inputs, not RCA therefore minimizing ground loop hum when using external amps.

grumpy
10-25-2010, 08:15 AM
Hi George, I'll offer an alternative view :)

I would not bother bi-amping the C37's and would think the receiver would have
-more- than enough power to drive the D130/075 combo, with plenty of reserve to
drive other speakers, should you desire to do so. My only significant concern would
be with the level of hiss produced through those very efficient speakers (and it may
not be a problem at all). I have an Onkyo A/V receiver (essentially one generation older
than the NR-708) and have not noticed this as an issue, but you might want to test
this to see if it is noticeable or bothersome.

That unit does seem like overkill, feature-wise, for a 2-ch system, but that may not
be your end goal.

jerry_rig
10-25-2010, 02:20 PM
George,

Just skimming the manual of the Onkyo TX-NR708, it seems its internal crossover will a) not let you run anywhere near the 2600Hz point needed for your 075s and b) does not output the subwoofer channel in stereo. I would agree with Grumpy and if you want to add a (single) subwoofer, you can do this at any time.

lgvenable
10-25-2010, 05:18 PM
Grumpys right in his point. The amp probably can drive the pair of speakers w/o a prob. If you use bi-amp etc like me, be prepared to do a parametric EQ for best results.

BMWCCA
10-25-2010, 06:52 PM
Or...more expensive but more accurate
buy a pair of BGW 750C for the bottom end, a pair of BGW 250D's for the mids/HF that'll give you all the power you need to drive the 130's and 075's.
Having in my lifetime powered an 030 system with the earphone output from a ChannelMaster transistor radio, I can't imagine why you'd need (or benefit from) anything like that on this system! Though it might be fun to try! :D :eek:

My 030s spent much of my college experience playing to the Blue Ridge Mountains from the back porch of a farmhouse powered by one Gen-1 Crown D150. None of the thousand party-goers over the years ever said anything that wasn't complimentary about the JBLs' sound.

I have thought about using my Crown VFX2As to bi-amp or tri-amp my 030s and to add an LE175DLH. I even bought a Crown D75A just for that purpose. Haven't gotten around to it yet. :dont-know:

George Beckwith
10-29-2010, 12:50 AM
Thanks for all your speedy replies. As you may have surmised, I just recently discovered audioheritage.org. I find it full of interesting information and history, but most impressive are the Forum contributors. I definitely plan to make a donation to help keep this community going.

On the D-130/075s, I find my thinking aligned with grumpy and jerry rig. I know that the Onkyo NR-707 is overkill, but want it for the HDMI inputs, Internet radio, etc. I did a frequency sweep (20-20kHz) on my D130/075 and it was so seamless that I can't envision bi-amping would improve the sound, so I have pretty much given up the ideal of bi-amping.

grumpy thanks on the heads up on possible hiss -will be particularly sensitive to this. I was considering adding a (single) subwoofer, but as jerry rig points out I can do that at any time.

I really appreciated lgvenable and BMWCCA comments, but they may exceed my needs and sophistication. I will continue to study these post.

Let me know any other thoughts :)