Output Impedance and Speaker Impedance

Before you read the rest ubbcbus , the Aerial Acoustics 5T is not an overdamped design, it’s normal.

A loudspeaker can’t be overdamped electrically, this is why some of the best amps for bass are from class-D, that have output impedances in the milli-ohms, damping factors of 10,000 or more and why they are great for subwoofers.

However you can have too much damping if the electrical damping is combined with too much mechanical damping in "over damped" enclosure design.

A typical example was the Linn Isobaric speaker which had very lean almost no bass with big Krells of the era, who would have thought a Krell with no bass!!!!
I actually heard a Naim amp with very mediocre damping factor sound better than the Krell into the bass of the Linn Isobarics.

BTW: this overdamped speaker with underdamped amp, was a great marketing strategy thought up by Linn/Naim at the time, you had to get both their amps and speakers, one did sound right without the other in A/B’s at shops.

Cheers George

Thank you ALL for your responses. I'm relatively new to AG and lurk daily, but do not have much to add to the knowledge base so I don't post frequently. Really appreciate the knowledgeable veterans replying to my inquiry. Regarding the responses:

@millercarbon - not a home theater, only for music. I started out with the 7900 and the Aerials, but was pining for more bass (48Hz wasn't cutting it). Listened to a few sub-woofers but was not impressed with what I heard. I listened to the Triton's and was impressed with the bass response (especially considering the price). I know these get poo-pooed on the forum and that's OK, I know what I like. After reading up on AG about tube sound and sound staging, I decided to invest in the 275 knowing that it could be piggybacked on the 7900 to power the Tritons. Granted, it's an odd approach but it's synergistic in a sense. SS + tubes, good midrange and highs (especially voice) from the Aerials and good lower frequencies and sound stage from the Tritons... I've never been too conventional.


George- overdamped room for sure. Been considering taking up the carpeting and putting down cork floors.


 @bdp24 - M.R. amps may have different wattages for different impedance ? The 7900 & the 275 claim same wattage for all impedances as @pragmasi pointed out. I'm going to check in with Aerial to see what they have to say. 


@ pragmasi - regarding the resistors, the Aerials have 4 connection posts. +'s and -'s upper and lower. The upper and lower posts have  bridge connections  i.e. + to + / - to -. Right below the upper posts is labeled "midrange and treble" . Could these potentially be resistors or a bridge that functions in the manner you speak of ?   


@onhwy61 - Yes, both sets of speakers at the same time. I have a decent sized listening room 18x30. Its has 45 degree pitched walls, two dormers and a funky diamonded shaped cut out for the pitch of the adjacent, perpendicular roof. With 4 speakers, it's an acoustic circus but pretty enveloping sound. At medium to higher volume, if you close your eyes you cannot tell where the speakers are placed. 


@atmasphere  - do you think there is a chance to damage the drivers by overdamping them ? They're paper (papyrus if you're so inclined :) The bass when connected to the 4 ohm posts is less pronounced....  maybe another question for Aerial

Thanks again to ALL of you,

Uncle BB 

Thanks again George. As I get more in to this hobby, seems I'll need to do some reading on classes of amplifiers and speaker pairing. There's a lot to learn. I have a Unit Atom and when the firmware went awry with my 7900, I hooked up the Aerials to the Atom (40 watt amp) so I could listen to music. It sounded a lot better than expected. And conversely, when I hooked them up to the 275 they sounded very thin and anemic. Your point is well taken. 

Best regards,

Uncle BB     

@bdp24 Thanks for the info. SS and tube power is a perplexing, abstract concept. I'm still trying to wrap my head around impedance, volts and wattage. But what I do understand, traditional tube amps do better with higher ohm rated, more efficient speakers. I took a look at the RM-200 hybrid online. Again, in my simple mind, bending the laws of physics. When it comes to tubes it makes me wonder if true tube sound is adulterated by autoformers, hybridization of the power supply and other technologies that have been developed to improve variables in tube amps.... Probably start a small war posting this question on the forum. Sound is like bourbon and artwork, price doesn't necessarily make it better. You like what you like. 

Regards, 

Uncle BB