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ATOM or THX headphones amp for efficient speakers?

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#1
I read that the JDS Labs ATOM and the Massdrop THX AAA 789 are pretty powerful for headphones amplifiers.
They can output 3-4w if I recall.

I definitely hear that on my ATOM with headphones.

I was wondering if those amps could be feeding efficient speakers directly.
I am not super familiar with speakers, but it's in my future plans to get some once I decide to pop out my head of my headphones and see the outside world...

I've read for instance that the new Klipsch RP-8000F are 98dB efficient and that 1W could drive them.

What realistically would be possible to get in terms of sound quality with such speakers and the ATOM or the THX?
and how would they be wired to each other? Via the headphones out or via the bypass out?
 

GoMrPickles

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#2
Not sure what's theoretically possible, but driving non-powered speakers with either amp may void your warranty. It is certainly explicitly not recommended in the THX docs.

However, you can use the line out to drive powered speakers that accept a line in, and that sounds great (that's part of my current setup: amp line out to some 15 year old Klipsch ProMedia 2.1s).

If you want to BUY speakers, you can get powered studio monitors, and use the RCA or XLR (dep on speaker) from a DAC; no need for an amp. Of course, if you listen to headphones AND speakers at your desk, the THX might be a nice choice, as it has 4-pin out, 3.5 mm out, and 6.5 mm out.
 

solderdude

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#3
The Atom is current limited around 200mA.
So max output power in 8 Ohm will be around 0.3W

Only the THX would be interesting for driving speakers BUT as the output device does not have any cooling it will go in protection mode sooner or later.
The output devices can deliver max 1.5A.
The output R (1 Ohm ?) is a bit high for usage with speakers.

Use a speaker amp instead
 

FrantzM

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#4
Hi

unrelated perhaps. I recently purchased on a whim a Koss electrostatic headphones. Can I use an iFi nano to use on the Koss interface box? You’re suppose to attach it to your regular amp speaker output.
 

andreasmaaan

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#5
I've read for instance that the new Klipsch RP-8000F are 98dB efficient and that 1W could drive them.
Manufacturers often inflate speaker efficiency specs. My guess is low-90s in the bass. And the spec sheet rates the impedance at 8-Ohm compatible. Not sure what that means, but I suspect that the impedance drops below 8 Ohms in the bass. This is all just speculation of course, but a pair of 8" woofers are very unlikely to be 98dB efficient in 4pi space. I know that Stereophile measured a couple of Klipsch speakers (google "stereophile klipsh measurements") and found them to be 3-4dB less sensitive than spec. They will be more efficient than many other speakers, though.
 

solderdude

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#6
Hi

unrelated perhaps. I recently purchased on a whim a Koss electrostatic headphones. Can I use an iFi nano to use on the Koss interface box? You’re suppose to attach it to your regular amp speaker output.
It depends on which energizer you have .
The older ones needs to be connected to a power amp.
The E90 model is line level input AFAIK. No problem to connect that one to the ifi.
 

FrantzM

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#7
I have bought recently, perhaps one of the very first : Koss ESP-9 & E.9 Energizer ... It can directly powered by the speakers from what I read (No AC POwer needed) but it also have a regular AC powered interface. I suppose it would present a high impedance load to an amp ... Time to look for the schematics on the 'net. :)
 

solderdude

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#8
There are 3 different types of energizers.

1: self biassing which only needs a power amp to drive. It works by 2 audio transformers and the audio signal is also rectified to create the bias voltage. Not recommended as it takes time for the bias voltage to reach a steady level.

2: Bias voltage using mains and 2 audio transformers to be connected to a power amp.
Requires a poweramp and mains socket. You need to switch the energizer on when you want to listen to music.

In both cases above the load impedance goes from very low (lowest subbass frequencies) to rather high (mids) and back to low again, for the highest frequencies (but capacitive so voltage and current are not in phase).
It thus requires a high voltage and current (hence the need of a power amp)

3: the new E90 model which is powered with 12V. Needs a mains adapter. This one has a buitl-in amplifier and thus is line-level input.
Needs to be switched on and works basically as a headphone amplifier (but for stats only)
 
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