Hi, I hope you can clarify my doubts, i feel quite confused.
I bought a JDS Lab Atom, to use as a preamp.
The Atom is a small and inexpensive headphone amplifier and preamplifier, based on an opamp design, famous for its reference measurements (THD, noise, frequency response, SNR).
Before purchasing I asked JDS Lab and they assured me that the Atom, with its 8.6V output, would drive my Gamut D200i power amp very well.
But when the Atom arrived home, I found a thin sound, lacking in energy, lacking in driving power. A very small soundstage in both width and depth, an anemic sound, lacking body and fullness.
My DAC is a Bryston BDA coming out at 2.19V from its unbalanced outputs.
My power amp is a Gamut D200i in low gain mode, requiring 3,9V to reach its full power.
The Atom applies a gain of 4.5x, so 2.19 * 4.5 = 9.85V, well beyond my power amp requirements.
I compared it with a Mark Levinson 28 preamp that has a max output voltage of 6V and applies a gain of 12 dB (4x), so
2.19V * 4 = 8.76V.
Despite the theory to the contrary, the Mark Levinson (as well as all the other preamps I have) drives my power amp much more powerfully.
Depends on what? Since the output voltage is even higher in the Atom?
I then compared it with other preamps:
- ARC LS12;
- Project Pre Box DS2;
- Spectral DMC20S2;
Same story, weakness.
Finally i tried the Atom as an headphone amp and compared it to the "DOCET Cuffia AMP" headphone amp in driving my AKG K702 headphones.
AKG K702 headphones requires about 3,6V to reach a 115 dB SPL level; despite Atom amp output 9,85V, same story: weakness.
So I emailed JDS Lab, asking if it could be a low current matter (it otuput "only" 1W on a 32 Ohm load), but they replied that power only depends on volume (voltage).
I do not know what to think.
Someone can clarify me what is happening?
Thanks,
Marco
(sorry for my bad english)
I bought a JDS Lab Atom, to use as a preamp.
The Atom is a small and inexpensive headphone amplifier and preamplifier, based on an opamp design, famous for its reference measurements (THD, noise, frequency response, SNR).
Before purchasing I asked JDS Lab and they assured me that the Atom, with its 8.6V output, would drive my Gamut D200i power amp very well.
But when the Atom arrived home, I found a thin sound, lacking in energy, lacking in driving power. A very small soundstage in both width and depth, an anemic sound, lacking body and fullness.
My DAC is a Bryston BDA coming out at 2.19V from its unbalanced outputs.
My power amp is a Gamut D200i in low gain mode, requiring 3,9V to reach its full power.
The Atom applies a gain of 4.5x, so 2.19 * 4.5 = 9.85V, well beyond my power amp requirements.
I compared it with a Mark Levinson 28 preamp that has a max output voltage of 6V and applies a gain of 12 dB (4x), so
2.19V * 4 = 8.76V.
Despite the theory to the contrary, the Mark Levinson (as well as all the other preamps I have) drives my power amp much more powerfully.
Depends on what? Since the output voltage is even higher in the Atom?
I then compared it with other preamps:
- ARC LS12;
- Project Pre Box DS2;
- Spectral DMC20S2;
Same story, weakness.
Finally i tried the Atom as an headphone amp and compared it to the "DOCET Cuffia AMP" headphone amp in driving my AKG K702 headphones.
AKG K702 headphones requires about 3,6V to reach a 115 dB SPL level; despite Atom amp output 9,85V, same story: weakness.
So I emailed JDS Lab, asking if it could be a low current matter (it otuput "only" 1W on a 32 Ohm load), but they replied that power only depends on volume (voltage).
I do not know what to think.
Someone can clarify me what is happening?
Thanks,
Marco
(sorry for my bad english)
Last edited:
To be clear, the other preamps were normal in gain? Your amplifier gain is set to "low"?
Can you set your amplifier gain to "high" for testing? Seems like that must be the problem.
The amplifier's gain can range from 20.6dB to 34.7dB.
The preamp's gain can range from 0dB to 12dB.
If the preamp is at 0dB, then set the amplifier to high gain, and that should work normally.
If the preamp is at 12dB, you might be able to use the amplifier at low gain, but maybe not.
By the way, a gain of 6dB is a factor of two, not four. That is, 20 x log (2) = 6.02dB.
The preamp can drive even 150R with full output, so there is not a problem with a power
amplifier with a 20k input impedance.
Can you set your amplifier gain to "high" for testing? Seems like that must be the problem.
The amplifier's gain can range from 20.6dB to 34.7dB.
The preamp's gain can range from 0dB to 12dB.
If the preamp is at 0dB, then set the amplifier to high gain, and that should work normally.
If the preamp is at 12dB, you might be able to use the amplifier at low gain, but maybe not.
By the way, a gain of 6dB is a factor of two, not four. That is, 20 x log (2) = 6.02dB.
The preamp can drive even 150R with full output, so there is not a problem with a power
amplifier with a 20k input impedance.
Last edited:
Same gain, more or less.
Mark Levinson 28 was set to 12 dB gain (4x).
Atom was set to high gain mode (4.5x, a little more than 12dB).
Mark Levinson 28 was set to 12 dB gain (4x).
Atom was set to high gain mode (4.5x, a little more than 12dB).
Do you still not have enough gain, with both components set to high gain?
That would be indicative of a serious problem somewhere.
Is the line voltage set correctly? A 220V unit used on 110V would not function properly.
That would be indicative of a serious problem somewhere.
Is the line voltage set correctly? A 220V unit used on 110V would not function properly.
Last edited:
There has to be some sort of problem with your Atom. Possibly stupid question - is the correct input selected? It might be set to the 3.5 mm for some reason, and all you're hearing is crosstalk...
Have you set BOTH components to high gain, and is that sufficient?
Please answer all questions, otherwise we cannot help.
Please answer all questions, otherwise we cannot help.
No, I have set both preamp at the same gain setting.
Mark Levinson 28 max gain is 18dB, but is set It to 12dB (4x), so medium gain.
Atom is set to max gain, 4.5x.
So, since my DAC output is 2.19V, we have 9.85V with the Atom and 8.76V with Levinson.
Despite Atom output more voltage than the Levinson , the former is much more powerful.
Mark Levinson 28 max gain is 18dB, but is set It to 12dB (4x), so medium gain.
Atom is set to max gain, 4.5x.
So, since my DAC output is 2.19V, we have 9.85V with the Atom and 8.76V with Levinson.
Despite Atom output more voltage than the Levinson , the former is much more powerful.
Maximum RCA Analog Input Level (High Gain): 2.10 VRMS (+8.6 dBU)
Maximum RCA Analog Input Level (Low Gain): 8.65 VRMS (+20.1 dBU)
Press the gain button to toggle between low or high gain amplification. Always use the lowest gain necessary.
Low gain of 1.0x is well suited to driving efficient IEMs, while high gain easily powers demanding full size sets when paired with a 2VRMS DAC.
Dual Gain 1.0x and 4.5x
16VAC Power Adapter (Half-wave rectification. Bipolar power supply?)
Max Output @ 600Ω
125mW (8.68 VRMS)
Max Output @ 150Ω
502 mW (8.66 VRMS)
Max Output @ 32Ω
1 Watt (5.66 VRMS)
Apply from the generator 1v 1kHz to the input and measure the output in position (High Gain) and (Low Gain)
Maximum RCA Analog Input Level (Low Gain): 8.65 VRMS (+20.1 dBU)
Press the gain button to toggle between low or high gain amplification. Always use the lowest gain necessary.
Low gain of 1.0x is well suited to driving efficient IEMs, while high gain easily powers demanding full size sets when paired with a 2VRMS DAC.
Dual Gain 1.0x and 4.5x
16VAC Power Adapter (Half-wave rectification. Bipolar power supply?)
Max Output @ 600Ω
125mW (8.68 VRMS)
Max Output @ 150Ω
502 mW (8.66 VRMS)
Max Output @ 32Ω
1 Watt (5.66 VRMS)
Apply from the generator 1v 1kHz to the input and measure the output in position (High Gain) and (Low Gain)
Last edited: