[jrgeoffrion]

Hi,

Given the amazing customer service and prompt responses owners are getting from this owner's circle, I am posting my query here.

I should preface that I just moved to a new house, which means that I'm somewhat not familiar with the acoustics in my room -- adding another variable to the mix.

I just got new speakers. They have an efficiency of 87db and a nominal impedance of 4 Ohms. The recommended minimum amplifier for these speakers is 150 W.

My issue:
Although the voices and highs are absolutely wonderful, bass (low and mids) is almost not present. Thinking that this may be attributed to the speakers not being fully broken-in yet (or my room), I just kept breaking the speakers in.

I measured 7B-SSTs power consumption with a Seasonic Power Meter. During power up, the meter goes close to 400 watts. At idle, each 7B-SST consumes about 65-70 watts from the wall. When playing they consume about 80-130 watts (and that's in a 4 ohm load). At ear bleeding levels, the meter doesn't go much higher than about 130 watts. The 7B-SST specs state that the amp should consume about 215 watts at idle.

My questions:
1) Should the power consumption of my 7B-SST be closer to 215 watt at idle rather than the 65 watts I'm getting?
2) If the answer to 1) is yes, can this be the source of my very weak bass?

My issue could definitely be due to many variables. However, I just wanted to start here with the above questions as it may end my quest. If you have any questions about my set-up that I didn't indicate above, don't hesitate to let me know and I'll be happy to provide the answer(s).

Thanks in advance,

JR

[James Tanner]

Hi JR,

I will forward the wattage draw at idle question to engineering but I do not think this would in any way affect the bass response of the amplifier in your setup. Are you at 120 or 240 Volts?

Bass response (as well as a lot else) is usually very much a function of the speaker room interface. So speaker placement relative to boundaries is critical for overall tonal balance. The fact that the integrated sounds more balanced is interesting. I think it may just be that the overall power delivery of the integrated is shifted towards the low frequencies where the Bryston's power bandwidth is much more evenly distributed over the speakers impedance curve.

james

[James Tanner]

OK we will see what engineering has to say.

I have 7B's on a pair of MG3.6's in my soundroom at home and they are very quick and very full range. Here is a link describing my systems to give you some background.
http://www.audiocircle.com/index.php?topic=43966.0

Jim Winey the designer and owner of Magnepan uses 7B's on his 5.1 MG20 system in his home as well as using them to demo his speakers at shows. So short of there being something weird about your two amplifiers it seems very strange.  Also the fact that both amps have the same issue would indicate that a similar problem with both amps is very unlikely.

A really obvious question - I assume you have checked to make sure your 7B's are "in phase"?

james

[James Tanner]

Hi JR,

Well sir I am at a loss.  Engineeing tells me that the idle power consumption would in no way affect the performance of the amplifiers.

james

[jrgeoffrion]

ISSUE RESOLVED (it was "the room"). Thanks for *all* the help.

[James Tanner]

If you want to send the amps back to be checked out ask for Mike Pickett.

james