• Welcome to ASR. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Adcom is back?

tmtomh said:
You can find Adcom power amps from the late 1980s and early 1990s that were made in Japan and China. I know for a fact that some runs of the same model - for example the GFA-5400 were made in both. I’m unaware of any performance or longevity differences between them.
Click to expand...
I had an Adcom power amp in the early 1990s or actually it was my older brothers but I used it a lot. I don't remember the model but I'm pretty sure it was made in the USA. It might been a little older maybe from the late 1980s because it was used from a high end stereo shop. It was a monster of an amp and seemed to be well made but was sold off still working fine long ago.
 
Mark1 said:
I had an Adcom power amp in the early 1990s or actually it was my older brothers but I used it a lot. I don't remember the model but I'm pretty sure it was made in the USA. It might been a little older maybe from the late 1980s because it was used from a high end stereo shop. It was a monster of an amp and seemed to be well made but was sold off still working fine long ago.
Click to expand...

Yes, sorry I wasn’t clearer - they had amps that were made in the US, Japan, and China.
 
mhardy6647 said:
I always have trouble with this!
:facepalm:

Doesn't it depend (i.e., on the order of 3 dB) on whether the quantity in question is voltage or power?
Click to expand...
Indeed. Halve those dB numbers if you are actually dealing with two measurements of the same thing.
 
mhardy6647 said:
Doesn't it depend (i.e., on the order of 3 dB) on whether the quantity in question is voltage or power?
Click to expand...

"Voltage distortion in dB will always be twice as negative (in terms of the absolute value) as power distortion for the same percentage."

Comparison:
  • Voltage THD: 0.01% converts to -80 dB.
  • Power THD: 0.01% converts to -40 dB.
 
At one time I was running 2 Adcom GFA-555 II bridged, now they are in separate systems.

I also have a GFA-2535 in another system.

Great amps, built like tanks, they are all run at least once per week...

Ohms
 
Adcom always struck me as a very odd name for a hifi company. Sounds like they should have had billboards all around town or something instead.
;)
 
RayDunzl said:
"Voltage distortion in dB will always be twice as negative (in terms of the absolute value) as power distortion for the same percentage."

Comparison:
  • Voltage THD: 0.01% converts to -80 dB.
  • Power THD: 0.01% converts to -40 dB.
Click to expand...
I actually think that way of putting it adds to the confusion. What is "voltage THD"? What is "power THD"?

If we are measuring (signal in volts)/(distortion in volts), expressing it as a dB ratio, the 10 dB per 10X rule applies.
If we are measuring (signal in SPL)/(distortion in SPL), expressing it as a dB ratio, the 10 dB per 10X rule also applies.

The critical thing is whether the numerator and denominator are in the same units, like in the two examples above.

When the numerator and denominator are different units, then the linearity of the relationship between the two units comes into play.

For example (and this is the common way of expressing voltage distortion as dB of SPL):-
  • SPL is proportional to power, and power (hence SPL) varies as the square of voltage, with an exponential power of 2.
  • Hence if the voltage ratio of distortion to signal is 1 in 10,000, the SPL ratio of distortion to signal will be 1 in (10,000 squared), ie 1 in 100,000,000. And that's why the dB is -80 dB instead of -40 dB.
It would not be right to suggest that when the ratio of two voltages is 1 in 10,000 (0.01%) and the ratio of two powers is 1 in 10,000 (0.01%), that they convert to different numbers in dB (-40 dB being the case in both instances).

cheers
 
Bruce Morgen said:
FWIW, this (apparently upcoming) Class D power amp -- based on Pascal modules -- is touted as "Designed, Engineered & Assembled in the USA.": Adcom GFA-D2500
Click to expand...
Except for the foreign-made Pascal modules themselves and other components as well. In total, I would wager that 75% of the components are offshored and most of them are made in China.
 
mhardy6647 said:
Thus "assembled in USA" as opposed to made in USA. :facepalm:
Words. They're a thing. ;)
Click to expand...
You are asking me to reed? Heavens forbid!

I stand corrected.

I should have added some words of my own, like "Assembled is a word that manufacturers like to hide behind". I should have taken some time...

Happy Easter!
 
Willied said:
.... "Assembled is a word that manufacturers like to hide behind" ....
Click to expand...
One of my favorite was a set of plastic molded splash guards for a car. The label said "assembled in the US", so I guess they put them in the bag in the US?

But it is such a grey area because other manufactures do most everything in the US but stick to the 'assembled' claim because they can't guarantee always that every part came from within the US.
 
ta240 said:
One of my favorite was a set of plastic molded splash guards for a car. The label said "assembled in the US", so I guess they put them in the bag in the US?
Click to expand...
They also put the label on. Can you imagine the job satisfaction in putting an assembled in the USA label on a lump of plastic, though I was asked to do dumber things by managers.
 
You must log in or register to reply here.

Similar threads

S
Amp to power 2 atmos speakers?
Replies
6
Views
654
Smieszny
S
X
Is my new SMSL DO100 Pro incompatible with my vintage stereo system?
Replies
4
Views
536
Xcollx
X
K
Ohm Walsh 5
Replies
4
Views
643
kathrynk
K
M
Amplifier pairing with APT Holman
2
Replies
25
Views
2K
Mark185
Mark185
J
Ordering integrating OG Analog preamps with Wiim Ultra as hub
Replies
1
Views
447
john61ct
J
Back
Top Bottom