[gkinberg]

I wanted to ask other songtower owners this question. I just purchased and received a Mcintosh MC 7106 amplifier. It is rated at 6 x 100 Watts/8 ohms; 6 x 160 Watts/4 ohms or bridged up to 3 x 320 Watts/8 ohms. It expressly says not to bridge with speakers that are less than 8 ohm load. I want to bridge this amp to feed my front three Songtowers. Is the mandate in the manual for the amp just "idle" engineer speak or is to be headed. Any input or experience would be appreciated.

Thanks, Garth

[Tone Depth]

You are likely to find your amplifier "be-headed" by not heeding the instructions in the manual.    The engineers that designed your amplifier have no reason to include unreliable information in the manual, they gave you good information to guide you on how to safely operate your amp.

I wanted to ask other songtower owners this question. I just purchased and received a Mcintosh MC 7106 amplifier. It is rated at 6 x 100 Watts/8 ohms; 6 x 160 Watts/4 ohms or bridged up to 3 x 320 Watts/8 ohms. It expressly says not to bridge with speakers that are less than 8 ohm load. I want to bridge this amp to feed my front three Songtowers. Is the mandate in the manual for the amp just "idle" engineer speak or is to be headed. Any input or experience would be appreciated.

Thanks, Garth

[R Swerdlow]

+1 for what Tone Depth says.

Just curious, do you find that a single unbridged channel on that amp is not enough power for SongTowers?

[ccotenj]

when you bridge an amplifier in this way, it halves the impedance "seen" by the amplifier...  thus if you connect a nominal 6 ohm load to it, the amplifier "sees" a nominal 3 ohm load...  which will kill the amplifier, especially given that impedance curves aren't linear and you are likely to have some pretty significant dips below that nominal load...

which is why they tell you not to do it...  not just "idle engineer speak"...  it's to keep you from turning your amplifier into a molten pile of metal... 

[gkinberg]

I am listening to it now and have it hooked up normally. It is an improvement over my Onkyo receiver. So Far sounds as though the detail and the command at low frequencies is better. My thought process when purchasing the amp is that I would bridge the channels to run my front three. I did not read the manual before purchasing the amp so wasn't aware of this stipulation.

My comment about idle engenier speak is that companies have to cover their a$$es and set limits so that they are not liable when their products are abused beyond reasonable limits. However, impedance curves are quite variable and some might be more amenable to a bridging scenario than other and could be used without damage. But the Songtowers do dip to 4 ohms in two places and therefore would be 2 ohm dips bridged which is likely outside the design capacities of this amp unfortunately.

I appreciate everyone’s advice. Thanks, Garth

[jsalk]

The SongTowers average about 6 ohms and dip to 4 ohms in two very narrow bands.  They are a relatively easy load for just about any amp and we have had not reports of any amp that could not handle them.

McIntosh rates their equipment conservatively.  So you are probably running about 130 watts into 6 ohms.  That should be more than plenty for the SongTowers. 

I think the advice you were given above it good advice.  I would not bridge this amp.

- Jim

[ricardojoa]

The SongTowers average about 6 ohms and dip to 4 ohms in two very narrow bands.  They are a relatively easy load for just about any amp and we have had not reports of any amp that could not handle them.

McIntosh rates their equipment conservatively.  So you are probably running about 130 watts into 6 ohms.  That should be more than plenty for the SongTowers. 

I think the advice you were given above it good advice.  I would not bridge this
amp.

- Jim

hi Jim, since we are on this topic, is the song center a 4 ohm as listed on the site or more like the song towers?

[DMurphy]

hi Jim, since we are on this topic, is the song center a 4 ohm as listed on the site or more like the song towers?

They both have the same impedance profile.  It drops to 4 ohms between 150 and 400 Hz, and narrowly at around 3 kHz.  The rest of the time the impedance varies between about 6 ohms and the typical peak of around 15 ohms due to the crossover network.  Impedance is usually "nominal", particularly on a 2-way.  There will be wide swings in impedance, and the rating is generally based on the minimum in the midbass, which will present the maximum load to the amplifier. 

[gkinberg]

Hi Denis,

Dumb question, what frequency range is "midbass"?

Thanks, Garth

[Nuance]

Hi Denis,

Dumb question, what frequency range is "midbass"?

Thanks, Garth

I am not Dennis, but...generally midbass is around 45 or 50Hz to around 100 to 120Hz or so.  However, there is no definitive definition, so for some it could be 100-200Hz.  My personal take is that it is where most of the slam comes from, but YMMV.

[ccotenj]

^^^

i'd agree with your definition brandon...  i've always thought of "midbass" as the "middle area where you (somewhat) equally 'feel' and 'hear' the sound"...  probably not the best definition of it, but it works for me...  :p

vs. mids/highs that is almost all "hear" and bass that is almost all "feel"... 

imo/ymmv/etc.

[DMurphy]

I was kind of bending the definition here to coordinate with speaker impedance realities.   I was by inference talking about the range between 150 and 400 Hz.  That definitely gets into midrange territory, although 150 Hz is pretty low--that would be a bass-baritone singing almost two octaves below concert A, or a couple of notes below low C.  The impedance curve for virtually any speaker will start rising below 150 Hz or so because of the woofer's resonance in the cabinet.  The low point in the impedance curve will generally be higher up--150-200 Hz is common.  So that will prove the greatest challenge for an amp that's not happy with 2-4 ohm loads, even though it's not really "bass" or maybe not even "midbass."