4315A Impedance Curve?

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11-29-2004, 07:26 PM
johnaec

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4315A Impedance Curve?

I've got a "problem" with the 4315A's I recently acquired in that they constantly throw a JVC receiver I have, (I know, I know... :( ), into "overload" mode and shut down the receiver at only medium levels. It's rated at 130 wpc, but at 8 ohms *minimum*.

Based on the image below that Giskard previously posted on the 4315B impedance curve, I'm guessing the 4315A's run substantially below 8 ohms at several points, and this is what's causing the receiver to go to safe mode shutdown. It hasn't happened yet with my L65A's, and I swear even the L60T's go to a louder volume than where the receiver shuts down with the 4315A's. Does this sound plausible? And does anyone have an impedance curve for the 4315A's?

Thanks - John

4315B curves as posted previously by Giskard:
11-29-2004, 08:57 PM
4313B

The 4315A and 4315B using the 3114A should have similar impedance curves. The original 4315 using the original 3114 would be slightly different.
11-30-2004, 04:29 AM
Guido

Wow, 2 Ohms @ 650 Hz!

That's an amp challenge.

Is the 4343 impedance available somewhere?
11-30-2004, 06:28 AM
johnaec

Quote:

Originally Posted by Giskard

The 4315A and 4315B using the 3114A should have similar impedance curves. The original 4315 using the original 3114 would be slightly different.

Thanks, Giskard - I pretty much assumed that'd be the case. 'Looks like I need something a little more robust for the 4315's...

John
11-30-2004, 11:34 AM
GordonW

Yeah, you definitely want a 2-ohm-stable amp on that one. Something like an NAD C272 power amp or NAD C372 integrated amp should work fine. I should know, I've run its little brother (the C320BEE integrated amp) on THREE PAIRS of L100s in parallel (a HARD 2 ohm load THROUGHOUT the frequency range!) and it just laughed at it... at output levels that would make your PANTS LEGS VIBRATE... :D

Is this JVC a theatre (5.1 Dolby Digital) receiver? If so, does it have line out jacks for the front two channels? If that's the case, you could just hook up an outboard amplifier to JUST the 4315s, and leave the rest of the system on the JVC internal amp. Bet it would sound better, even on the REST of the speakers, to have the JVC power supply ONLY running three speakers instead of 5!
11-30-2004, 11:59 AM
johnaec

Quote:

Originally Posted by GordonW

Is this JVC a theatre (5.1 Dolby Digital) receiver? If so, does it have line out jacks for the front two channels? If that's the case, you could just hook up an outboard amplifier to JUST the 4315s, and leave the rest of the system on the JVC internal amp.

Yep, the JVC is a 5.1 receiver - I believe it has separate pre-outs, but I'll have to check. I picked it up on a local close-out - only later did I catch that 8 ohm minimum spec. I have an early JVC digital stereo receiver with 60/wpc and I've driven two pairs of L65's paralleled concurrently all day long at high levels without a hint of a problem. I guess squeezing 5 channels of "high" power in these new receivers means they had to cut corners someplace...

John
11-30-2004, 01:19 PM
GordonW

Yep, and the corners 99% of the manufacturers cut, is the power supply and output heatsinks. Those are the parts that require REAL METAL...

Really hefty, capable HT receivers are rare... other than NAD, Marantz, high-end Yamaha (over $1000) and such units, most other stuff is built to run 2 channels wide open, but will choke when all 5 channels are driven hard...

Regards,
Gordon.
11-30-2004, 02:29 PM
johnaec

Quote:

Originally Posted by GordonW

...most other stuff is built to run 2 channels wide open, but will choke when all 5 channels are driven hard...

This newer JVC chokes with only 2 channels medium volume and 4315's - forget wide open or 5 channels... :rolleyes:

Assuming the JVC has some pre-outs, I'll try running the 4315's with one of the Crest amps I have - they're pretty much known for their stability. I can also configure all sorts of different "direct" type setups and bypass the JVC completely - it would just be nice for switching and control convenience...

John
11-30-2004, 08:03 PM
johnaec

Quote:

Originally Posted by GordonW

Is this JVC a theatre (5.1 Dolby Digital) receiver? If so, does it have line out jacks for the front two channels? If that's the case, you could just hook up an outboard amplifier to JUST the 4315s, and leave the rest of the system on the JVC internal amp.

I checked this evening and the JVC *does* have pre-amp outs for all 5.1 channels, and even a separate mono subwoofer output with adjustable crossover frequencies. 'Time to start playing around with the Crests...

John
12-01-2004, 09:06 PM
johnaec

OK - 'hooked the 4315's up to a little Crest 1501A, (125 wpc @ 4 ohms), using the JVC receiver as a preamp, and no problem at all driving them to ridiculous levels. 'Had a scare first, though - no LF through one channel - 'thought maybe the previous issues had done some damage. Pulled the speaker, tested the DCR, made sure the connections were good, put it back in and voila - it works fine.

I did notice the UHF on the same side is down substantially from the other - 'swapped inputs to be sure. 'Guess I'll have to swap the 2405's and check all the regular stuff to see what's going on...

John
12-01-2004, 11:56 PM
Mr. Widget

Quote:

Originally Posted by johnaec

OK - 'hooked the 4315's up to a little Crest 1501A, (125 wpc @ 4 ohms), using the JVC receiver as a preamp, and no problem at all driving them to ridiculous levels.

Even the "best" receivers can't compare to a decent power amp. I own a couple of high and higher end receivers and use them as surround processors with built in rear channel amps. For the front channels I just have to use real amps... it is too bad too because it really adds to the domestic clutter.

Widget