[ctviggen]

I have Lexicon NT 5-channel amplifier (basically a Bryston 9B), which produces 120 watts/channel 8 ohms and 200 watts/channel 4 ohms.  However, I have a "final checkout" sheet that lists the measured power as being 163watts/channel into 8 ohms at clipping at 2kHz, so the amp is more powerful than the specs might indicate.  

I used to have my RM30C driven biamped by two channels of the Lexicon NT.  Two other channels are for the right and left rear speakers. That means that four of the five channels were used.  I wanted to save two channels for speakers outside the house, which I'll be putting up once spring gets here.  So, I changed the configuration to use one channel (instead of two) of the Lexicon to drive the RM30C.  

Here's the problem.  Using Avia to set up the system requires playing test tones and measuring 85dB at the sitting position for each speaker when the system is at reference level (i.e., 0.0 dB on my Proceed AVP).  With the RM30C amped with one channel of the Bryston, I could not hit 85 dB, with the Proceed AVP set to maximal (+12dB) level for the center channel.  I could only hit about 83dB.  So, I had to adjust the level controls for the RM30C both up (to about 3 pm) to get the extra 2dB.  

Why would I have to do this?  Does my amp not have enough power for the RM30C?  The input sensitivity of the Lexicon is 1V for 28.28 VRMS (approximately 100 watts into 8 ohm).  Single channels of the Lexicon drive the rear speakers (Mirage monitors) and used to drive my Linn 5140s (4 ohm, floor standers with -3dB of 30Hz) with no problem.  Perhaps there's an efficiency issue?  Are my other speakers more efficient than the RM30C?  It should be noted that the rear speakers are also closer to me than is the center channel.

Anyway, I'm trying to figure out what to do here.  Do I use Avia but measure to only 80dB, thereby allowing me to set the level controls on the RM30C to my liking?  (And I do like to change these for better voice reproduction; now, I can't do this.)  Do I go back to biamping and then just buy a cheap two channel amp for the outside speakers?  Do I buy a nice monoblock for the center channel (say, a nuforce Reference 9)? Perhaps I could do something really "radical" like buy a tube monoblock to run the highs and use a channel of the Lexicon to run the lows of the RM30C?

[Marbles]

Bob, does AVIA reduce the output such that at 85DB it EQUALS what the sound will be at reference (105db)?

I seem to remember something like that, but I'm not sure what it was exactly.

[Stevo]

Sounds like the Lexicon NT 5-channel amplifier should have no problem driving an RM30C; here's a quick comparison:

Just did a quick check with my RM30C as a reference point.  Placed a test tone using the Anthem AVM-20 at -7.0db.  The AVM-20 outputs (analog) to a Panasonic SA-XR55 (analog DVD in).  With the Panasonic at set to -10 volume, the RM-30C output level was measured around 82db from 15 feet away.  With the Panasonic set to -4 on the volume, the sound was measured around 88db.  I boosted the output slightly on the preamp, and the levels flew over 90db (didn't go higher; ears were screaming).


Without getting lost in the numbers, I'm simply attempting to show that an inexpensive receiver has no problem effortlessly driving the RM-30C to levels matched by the RM/X in SPL output.

The pots on my RM30C are set to around 12:00 - 1:00.  Hope this helps with your investigation.

[ctviggen]

Marbles,

I don't know.  That may be happening.  Perhaps I should actually go through the Avia disk to see if there's any information about this?  I typically just go right to the location of the sound files.  I seem to remember that a lot of the info. about Avia isn't really on the disk, as they "dumbed down" the disk.  For instance, I tried to set up the sub(s) last night, too, and remembered that Avia requires setting the crossovers to be 80Hz for some reason (which I did not do) to get a correct reading, so I think I'm off there.

Stevo,

Thanks for the information.  I would think my Lexicon/Bryston would be able to run the speaker at high levels, too, but this doesn't seem to be happening.  Maybe I'll try a different channel of the amp -- perhaps this channel is operating at a reduced capacity.

[jgubman]

Bob,

can you hit 85dbs using the internal test tones in the AVP?
Are you using the analog or digital outs of your DVD player? Is it possible that the dvd player's output voltage is off somehow?

AFAIK, Avia produces a -20dBfs signal on it's test tones.

[ctviggen]

Well, I tried a different channel of the Lexicon/Bryston with no success.  Jgubman, the AVP's test tones are at 75 dB, I believe.  I can easily hit those but am having a hard time hitting the 85 dB of Avia.  I have a Proceed PMDT as a DVD player, and it's a transport only.  I run the digital signal (using a balanced digital connection) into the Proceed AVP.   I've had no problems in the past using my former center channel (Linn 5120) or having my other surrounds hit 85dB, only the RM30C and only when driving it with one channel of the Lexicon/Bryston. Maybe I'll just go back to biamping the RM30C.   Before I do that, I think I'll go through the Proceed PMDT's manual to see if perhaps there's a setting I set incorrectly.

[ctviggen]

I ended up buying a single Nuforce Ref 9 to use for my center channel.  I wanted to buy three but couldn't afford them.   I was also considering the Ref 8 but was unsure if it would drive the RM30C.  All I did was disconnect the Bryston/Lexicon 9B and put in the Ref. 9.  I was able to decrease the center channel level in my preamp from the maximum (+11dB) to 8dB and also drop the mids and highs from the 3 pm position to about noon.  So, now at least I can play with the positioning of the pots to tune the system to my liking and I'll have an extra two channels of the Bryston/Lexicon to drive outdoor speakers.

[ctviggen]

The voices do sound better.  At one point, I thought that more noise was coming through. However, I think the Ref 9 isn't noisier per se; instead, it's simply amplifying what it gets and there's a lot of noise on the Antiques Roadshow.  I thought the voices were really fleshed out well.  Unfortunately, I didn't do a "before" and "after" test, so I'm going on just what I heard without such a test.  Nonetheless, the voices had clarity that I'm not sure the Bryston/Lexicon gave me.  I heard nuances in voices (they pretty much have the same specialists each time on the Roadshow) that I never heard before.  I'm impressed.  Now I'll have to perform another test with some DVDs and I'll have to have my fiancee help me tune the center.

[ctviggen]

Woops.  I guess max level on my preamp is +12dB, so I gained 4dB by using the Ref 9 instead of the Lexicon/Bryston 9B.  I also gained another few dB, as I've been able to turn down the pots on the RM30C.

[woodsyi]

Bob,

If ever get a chance would you mind trying the nuforce on your larger?  I have been wanting to try them on my largers (it has less power but higher damping ratio than my crown k2).

[John Casler]

The voices do sound better.  At one point, I thought that more noise was coming through. However, I think the Ref 9 isn't noisier per se; instead, it's simply amplifying what it gets and there's a lot of noise on the Antiques Roadshow.  I thought the voices were really fleshed out well.  Unfortunately, I didn't do a "before" and "after" test, so I'm going on just what I heard without such a test.  Nonetheless, the voices had clarity that I'm not sure the Bryston/Lexicon gave me.  I heard nuances in voices ( ...

As Ross Perot used to say "Problem Solved".

The NuFORCE/VMPS combo is quite good, and I recently tried an experiment that made it even better.  I ran longer XLR IC's to the Ref 9's and shorter speaker cable. I actually placed the Amps on top of the speaker.   I also used a new after market Power Cord.

Noticable improvement in most all areas, including bass definition and depth.

[ctviggen]

Woodsyi, I can easily hook up the Ref 9 to a Larger.  In fact, I could perform a pseudo-comparison:  I have one working channel on my QSC 3402 and I can hook up one Larger to that, then hook up my other Larger to the Ref 9. I can play music (even mono) and see what happens.  I do have a problem with one Larger, though, which is probably a wiring issue (the two drivers are likely wired out of phase).  I'll have to fix that first. I have the Ref 9 situated in a perfect spot to do this comparison.  If I can't do the comparison this weekend because of time constraints, I'll hook up the good Larger to the good channel of the QSC, play music/DVD, then hook the good Larger to the Ref 9, play music/DVD.  It won't be as valid (my short term memory isn't great), but I'll try to get some sense of the power and differences between the two amps.

John, the way I have things set up now, I'm also thinking of getting a short run of speaker cable.  As for power cords, I haven't thought about going down that road yet.  I want to move everything around, which will entail long balanced interconnect runs and short speaker connections.  I'm thinking of transitioning to all monoblocs for the front three speakers and getting rid of my Jeff Rowland.  This way, I could have monoblocks sit right behind/near the front speakers and have short speaker cables.  Right now, I'm using 16 foot speaker cables for the RM40s.  Yikes!  But that's what it takes.  The new situation would result in quite long runs of balanced interconnects through walls to monoblocs "hidden" behind speakers.  I'd hide all cables, too, which is going to make my significant other happy.  If I could've afforded to buy three Ref 9s, I'd do a comparison between the Ref 9s and my JR.  Maybe the Ref 9s would win?  That would save me cash!

[woodsyi]

Woodsyi, I can easily hook up the Ref 9 to a Larger.  In fact, I could perform a pseudo-comparison:  I have one working channel on my QSC 3402 and I can hook up one Larger to that, then hook up my other Larger to the Ref 9. I can play music (even mono) and see what happens.  I do have a problem with one Larger, though, which is probably a wiring issue (the two drivers are likely wired out of phase).  I'll have to fix that first. I have the Ref 9 situated in a perfect spot to do this comparison.  If I can't  ...

That will be great.  Take your time.  No hurries.  I got other things cooking that won't let me do anything about subwoofer amp for a while.

[John Casler]

Bob,

If ever get a chance would you mind trying the nuforce on your larger?  I have been wanting to try them on my largers (it has less power but higher damping ratio than my crown k2).

Hi Woodsyi,

I temporarily have 4 Ref 9's so I decided to connect the spare pair to the front LARGER subs and the BASS just moved up another LEVEL.

Many times, I'll run through my Reference Cuts and just listen "specifically" for the bass depth, detail, and dynamics (the 3-Ds)

The Ref 9s show sonics in Flight of the Cosmic Hippo, Tin Pan Alley, Cut from American Beauty Original Score, Hollie Cole's Get Outa Town. Several Diana Krall cuts with Bassist John Clayton, Rickie Lee Jone's Dat Dere, Black Light Syndrome, cuts from Cafe Blue, and Bad Plus.

Each and every one, displayed new detail and definition to the bass region.

The integration from RM30 to LARGER was superb and rightfully so, since all were run on the two pair of Ref 9s.

So I know this doesn't help you a lot since I have not had the K2 in my system, but the Ref 9s with the LARGER subs is a GREAT marriage.

[woodsyi]

Dang it John,

You are tempting me.  I may have to get one to compare.  It will have to be later though since I just spent a chunk with you.

[John Casler]

Dang it John,

You are tempting me.  I may have to get one to compare.  It will have to be later though since I just spent a chunk with you.

     Yes, that is true and I hope your new toy arrives tomorrow, with no more delays.

You'll have to give us a "report" after it is installed