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Amp capable of powering a Modhouse Tungsten

JIW said:
When connected to the A70 Pro, you should set the DAC's volume close to 0 dB but you should consider leaving it at -3 dB to avoid intersample overs and control the volume on the A70 Pro. Gain on the DX7 is only for its headphone output not the line-out.

No, for the DX7 at full output SINAD of the line-out is higher than SINAD of the headphone output in low gain.

What headphones do you use with low gain and volume between -11 and -17? What are the volume and gain settings when you listen loudly?
Click to expand...
Ok.
Im using LCD-X (2021).
So, when i'm listening loud, my amp (DX7) is showing -11dB and that is at Low Gain.
I rarely use high gain, but have tried to use it and setting the dB at lower, but didn't like it for some reason.
Why, i'm unsure of, it just didn't feel "right".
 
SicknessWin said:
Ok.
Im using LCD-X (2021).
So, when i'm listening loud, my amp (DX7) is showing -11dB and that is at Low Gain.
I rarely use high gain, but have tried to use it and setting the dB at lower, but didn't like it for some reason.
Why, i'm unsure of, it just didn't feel "right".
Click to expand...
Amir has measured the LCD-X (2021) to produce 94 dB SPL at 152 mV RMS which is the same as 94-20*log10(.152) = 110.36 dB SPL at 1 V RMS or 0 dBV. The DX7 Pro+ maximum output in low gain is 6.2 Vpp, i.e. 6.2/8^.5 = 2.192 V RMS or 20*log10(6.2)-10*log10(8) = 6.82 dBV. Thus, in low gain, the maximum peak SPL for the LCD-X is
94-20*log10(152/1000) + 20*log10(6.2)-10*log10(8) + 10*log10(2) = 120.19 dB SPL. At -11 dB volume, the maximum peak SPL is thus 109.19 dB SPL.

To get the same out of the Tungsten requires 23.09 dBV for the double sided and 24.49 dBV for the single sided. The DX7 Pro+ can do 22.86 dBV at most due to its output in high gain being 27.8 Vpp. For the double sided that may just be enough but not so much for the single sided.

The A70 Pro can do 28.63 dBV due to its maximum output being 54 Vpp. More than enough for the levels you use.
 
staticV3 said:
Most likely expectation bias.

If you had two level-matched DX7s in front of you - one set to Low and the other to High - you would not be able to tell them apart in a blind test.
Click to expand...
I do not doubt you for a second, and you are more than likely correct in assuming the bias.
It just felt like one was more screechy in the sound than the other, as in a low hum with a higher pitch on it.
That being the high gain setting.


JIW said:
Amir has measured the LCD-X (2021) to produce 94 dB SPL at 152 mV RMS which is the same as 94-20*log10(.152) = 110.36 dB SPL at 1 V RMS or 0 dBV. The DX7 Pro+ maximum output in low gain is 6.2 Vpp, i.e. 6.2/8^.5 = 2.192 V RMS or 20*log10(6.2)-10*log10(8) = 6.82 dBV. Thus, in low gain, the maximum peak SPL for the LCD-X is
94-20*log10(152/1000) + 20*log10(6.2)-10*log10(8) + 10*log10(2) = 120.19 dB SPL. At -11 dB volume, the maximum peak SPL is thus 109.19 dB SPL.

To get the same out of the Tungsten requires 23.09 dBV for the double sided and 24.49 dBV for the single sided. The DX7 Pro+ can do 22.86 dBV at most due to its output in high gain being 27.8 Vpp. For the double sided that may just be enough but not so much for the single sided.

The A70 Pro can do 28.63 dBV due to its maximum output being 54 Vpp. More than enough for the levels you use.
Click to expand...
But the DX on those volumes with high gain would most likely produce noise/distortion?
This would also mean that the A70 Pro would be an ideal AMP for the Tungsten?
I might check out the A70 Pro and the D70 stack.
Again, this is where i sadly do not understand much yet, the numbers part.
But as far as my knowledge takes me, in reading the numbers, the D70 does come out close to identical as the DX7 Pro+?

On a sidenote, do you or anyone else have any literature that you can recommend for understanding this better than i currently do?
 
SicknessWin said:
I do not doubt you for a second, and you are more than likely correct in assuming the bias.
It just felt like one was more screechy in the sound than the other, as in a low hum with a higher pitch on it.
That being the high gain setting.



But the DX on those volumes with high gain would most likely produce noise/distortion?
This would also mean that the A70 Pro would be an ideal AMP for the Tungsten?
I might check out the A70 Pro and the D70 stack.
Again, this is where i sadly do not understand much yet, the numbers part.
But as far as my knowledge takes me, in reading the numbers, the D70 does come out close to identical as the DX7 Pro+?

On a sidenote, do you or anyone else have any literature that you can recommend for understanding this better than i currently do?
Click to expand...

Based on Amir's measurements, distortion might be a problem but it is not at 300 Ohm so it might also not be. Noise will not be a problem with the Tungsten.
1738606128079.png


There is no benefit to getting the D70 together with the A70 Pro instead of using the DX7 Pro+ other than aesthetics. For your volumes, the L70 with an E70 DAC would also work for the Tungsten.
 
JIW said:
Output voltage being the same at 32 Ohm as 600 Ohm at (15.12*32)^.5 = 22.0 V RMS suggests high current output. At least (15.12/32)^.5 = 687.4 mA RMS. What is the power at 16 Ohm? Twice that at 32 Ohm or less?

With 14 dB gain, 10*log10(15.12*32) - 14 = 12.85 dBV or 4.39 V RMS input is required for full power output. This seems a lot since many balanced DACs only output 4 V RMS at 0 dBFS. Nevermind single ended connection being typically 2 V RMS at 0 dBFS. Why did you choose gain this low given the power the amp can produce?
Click to expand...
The max output current of the amplifer is 1.1A or 777.7mA RMS.

So at 16 ohm, the maximum output power will be less.
16 ohm -- 9.66W
8 ohm -- 4.83W

The amplifer was tested with multiple headphones of different impedance and sensitivities using different sources, both XLR and RCA and 14dB was determined to be the best gain to use. Even with devices that output 4Vrms you will get more than enough power for most of the headphones out there.
 
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orchardaudio said:
The max output current of the amplifer is 1.1A or 777.7mA RMS.

So at 16 ohm, the maximum output power will be less.
16 ohm -- 9.66W
8 ohm -- 4.83W

The amplifer was tested with multiple headphones of different impedance and sensitivities using different sources, both XLR and RCA and 14dB was determined to be the best gain to use. Even with devices that output 4Vrms you will get more than enough power for most of the headphones out there.
Click to expand...
It seems like it has fixed gain. Is that the case?

Sure 20 dBV is plenty for almost anything but you said it was supposed to power the Tungsten without problems. Anyways, those who want to get the most out of the amp may have to use a preamp. What is the maximum input voltage?

Measurements look good but are also still a good bit from the amp capabilities. Maybe a bit noisy but with 14 dB gain that is to be expected and it still being ~9 dB below full scale. THD at around -125 dB if I read it correctly. (8 V is 18 dBV, H2 at 1.5µV and H3 at 4 µV giving -(18+120-10*log10(4^2 + 1.5^2)) = -125.39 dB).
 
JIW said:
It seems like it has fixed gain. Is that the case?

Sure 20 dBV is plenty for almost anything but you said it was supposed to power the Tungsten without problems. Anyways, those who want to get the most out of the amp may have to use a preamp. What is the maximum input voltage?
Click to expand...
Yes, the gain is fixed.

It can power Tungsten with no issue, Mod House audio is evaluating one now and a second individual is using it with Tungsten as well. The unit puts out 22Vrms (26.848dBV) or 31.1Vpeak.

Yes, you will need to use a preamp (or something else with volume control) with this device, since the gain is set.
 
orchardaudio said:
Yes, the gain is fixed.

It can power Tungsten with no issue, Mod House audio is evaluating one now and a second individual is using it with Tungsten as well. The unit puts out 22Vrms (26.848dBV) or 31.1Vpeak.

Yes, you will need to use a preamp (or something else with volume control) with this device, since the gain is set.
Click to expand...

Since it seems to have no volume control, anything above 12.848 dBV input or 4.39 V RMS will overload the output stage anyways. I presume, the input stage can deal with that just fine.
 
JIW said:
Since it seems to have no volume control, anything above 12.848 dBV input or 4.39 V RMS will overload the output stage anyways. I presume, the input stage can deal with that just fine.
Click to expand...
Yes, the input can deal with much higher voltage, it's the output that is being driven into the rail (clipped).
 
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El_Arte said:
How much does it cost?
Click to expand...
It is discussed in the Zeos' Review posted here earlier by Orchard Audio. Around $2,000. I am not a member of his Patreon so cannot unlock the post for the preorder price.
 
JIW said:
It is discussed in the Zeos' Review posted here earlier by Orchard Audio. Around $2,000. I am not a member of his Patreon so cannot unlock the post for the preorder price.
Click to expand...

Ouch. OK. Thanks!
 
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