Adam Audio GTC77 Speaker System HT Labs Measures

HT Labs Measures

L/R Sensitivity: 90 dB from 500 Hz to 2 kHz

Center Sensitivity: 90 dB from 500 Hz to 2 kHz

Surround Sensitivity: 87 dB from 500 Hz to 2 kHz

This graph shows the quasi-anechoic (employing close-miking of all woofers) frequency response of the GTC77 L/R (purple trace), GTC77 horizontal center channel (green trace), GTC55 surround (red trace), and GTC Sub subwoofer (blue trace). All passive loudspeakers were measured with grilles at a distance of 1 meter with a 2.83-volt input and scaled for display purposes.

The GTC77’s listening-window response (a five-point average of axial and +/–15-degree horizontal and vertical responses) measures +1.65/–3.14 decibels from 200 hertz to 10 kilohertz. The –3-dB point is at 49 Hz, and the –6-dB point is at 39 Hz. Impedance reaches a minimum of 5.39 ohms at 511 Hz and a phase angle of –30.13 degrees at 96 Hz.

The GTC77’s listening-window response in horizontal mode measures +1.49/–3.39 dB from 200 Hz to 10 kHz. An average of axial and +/–15-degree horizontal responses measures +1.63/–2.93 dB from 200 Hz to 10 kHz. The –3-dB point is at 49 Hz, and the –6-dB point is at 39 Hz. Impedance reaches a minimum of 5.39 ohms at 511 Hz and a phase angle of –30.13 degrees at 96 Hz.

The GTC55’s listening-window response measures +1.29/–3.64 dB from 200 Hz to 10 kHz. The –3-dB point is at 49 Hz, and the –6-dB point is at 42 Hz. Impedance reaches a minimum of 5.70 ohms at 3.3 kHz and a phase angle of –43.22 degrees at 111 Hz.

The GTC Sub’s close-miked response, normalized to the level at 80 Hz, indicates that the lower –3-dB point is at 22 Hz and the –6-dB point is at 20 Hz. The upper –3-dB point is at 143 Hz with the Sub Filter control set to maximum. —MJP

Adam Audio USA, Inc

theo's picture


This is really a rousing and stellar review.

So, assuming the nearest dealer is 300 miles away, how does one compare these speakers vs B&W, Revel, Wilson, etc (You have the Alexandrias in your setup, correct?) Did you give these any serious two-channel runs as well and were you equally impressed with the 2-channel performance? Curious to hear your thoughts.


Mister Leadfoot's picture

Took a look at their website and the Tensor series look incredible visually. Very interested in listening to these, but as theo said above, its a bit of drive for me as well to the nearest dealer...

Stephen Trask's picture

I've been mixing on self powered Adam P11a for about three years. The have the same tweeter and one of the 7" drivers and they have been fantastic. I've been waiting for a review from someone like Mr. Fremer of their home theater products to see if there products translated as well in that environment. I guess so and I'm not surprised. i love my Adams and they sound great in imperfect spaces. Thanks for the review.

jt1's picture

Any concerns related to running these 4 ohm speakers with a Wyred 4 Sound 1000 watt 4 ohm amp?

Scott Wilkinson's picture
Not if the amp is rated to power 4-ohm speakers safely. In our measurements, the minimum impedance was 5.39 ohms, so this combo should be no problem at all.
jt1's picture


jt1's picture

Has anyone heard the GTC 88s? I am interested in the difference and whether it may be worthwhile for my front left and right speakers. Maybe an 88 for center or stick with the GTC 77? Trying to decide.

K.Reid's picture

Everything that Michael Fremer indicated about these speakers is absolutely true. I had a listening session with a pair of the Adam Audio Pencil Mk3...and they are phenomenal. That X-Art tweeter is really something special. I experienced no listening fatigue. Adam Audio was also at CES this year with their Column Mk3 - another great listening experience. I definitely recommend them.

savage's picture

Dear Mr.Fremer,
I have purchased a set of these speaker and found that once they are set up according to manufacturers instruction, particularly having them focused behind the listening position, they are wonderful! Great sound stage, detail, and very musical. They are the best speakers I've ever owned for two channel or multichannel.

But I am not sure about the sub-woofer set up. How did you set yours up?

My receiver is a 5.1 channel with limited left and right audio outs (tape and zone 2). The sub has right and left in and right and left out. So I am really curious about how to set them up properly for multi channel systems. I am asking this question directly to Adam Audio, but wanted your input and experience as well.
Thank for your insightful articles.

savage's picture

Mr. Fortier from ADAM Audio answered my question on a Saturday! He says that it is ok to use one cable from one Sub out to the sub woofer, although I did need to turn up the sound level.

Fabulous speaker system. I am very happy. Thank you again Mr Fremer you didn't lead me wrong.