Would you give the McIntosh MHA200 a chance?

[johny_2000]

I have the opportunity to test the McIntosh MHA200 tube headphone amplifier in real-life conditions.

The DAC will be devices with SINAD 120-125 dB.

The load will be a dummy load of 32-300 Ohms.

The measurements will be made using reliable tools to obtain THD, Noise, SINAD measurements.

Is it worth doing?

 

[Doodski]

I have the opportunity to test the McIntosh MHA200 tube headphone amplifier in real-life conditions.

The DAC will be devices with SINAD 120-125 dB.

The load will be a dummy load of 32-300 Ohms.

The measurements will be made using reliable tools to obtain THD, Noise, SINAD measurements.

Is it worth doing?

I am interested to see a amplifier frequency response graph with and without the MHA200 and substituting in a solid state amp to use as a reference in comparison. Then we can see if there is a output impedance variation.

 

[johny_2000]

I am interested to see a amplifier frequency response graph with and without the MHA200 and substituting in a solid state amp to use as a reference in comparison. Then we can see if there is a output impedance variation.

Could you please be more specific about the measurement conditions?

 

[Doodski]

Could you please be more specific about the measurement conditions?

You will need resistive loads/resisters and frequency sweep the amps and then plot that on graphs. I am guessing that you will use software/test gear to meter out the tests. Otherwise manually making the graphs could be done but that is very time consuming.

 

[johny_2000]

I have a 30 and 300 Ohm dummy load.
Measurements can be made in REW and Multitone software with an AES17@1kHz notch filter and an ADC with -127 dB THD+N.
Are you talking about a frequency sweep from 20Hz to 20kHz as a comparison?

 

[JSmith]

• Headphone Power Output500 mW
• Headphone Output Impedance 32-100 ohms
  100-250 ohms
  250-600 ohms
  600-1,000 ohms

• FTC Power Output Rating N/A
• Power Output per Channel N/A
• Speaker Impedance N/A
• Rated Power Band20Hz to 20kHz
• Total Harmonic Distortion 0.5% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20kHz
  <0.20% at 1W, 20Hz to 20kHz
• Intermodulation Distortion 0.04% Typical
  0.4% Maximum
• Dynamic Headroom 1.5dB
• Frequency Response+0, -0.5dB from 20Hz to 20kHz
• Sensitivity (Unbalanced)1.0 Vrms
• Sensitivity (Balanced)2.0 Vrms
• Maximum Input Signal (Unbalanced)8V
• Maximum Input Signal (Balanced)16V
• Signal To Noise Ratio 94dB
• Input Impedance (Balanced / Unbalanced)20K/10K
• Damping Factor>150
• Preamplifier OutputN/A
• Preamplifier Output ImpedanceN/A
• Voltage Gain12dB at 32 ohms
  17dB at 100 ohms
  21dB at 250 ohms
  25dB at 600 ohms

Meh...


JSmith

 

[Doodski]

I have a 30 and 300 Ohm dummy load.
Measurements can be made in REW and Multitone software with an AES17@1kHz notch filter and an ADC with -127 dB THD+N.
Are you talking about a frequency sweep from 20Hz to 20kHz as a comparison?

Yes. actually sweep up frequency till the 3dB down (1/2 power point.) cutoff point. So higher than 20kHz but 20kHz will suffice if you want to keep things simple. @JSmith has posted the spec of:

• Frequency Response+0, -0.5dB from 20Hz to 20kHz

 

[johny_2000]

@JSmith,
I understand your skepticism. I am in the same boat.
But this is a moment in history where we can make a connection between the best things of the past and the best things of reality.
I have heard so many things and rumors about tube amplifiers in my life that I want to give them one last chance to shine in the modern era, despite the possible parameters of THD and IMD, as long as they remain in moderate numbers below 0.5%. This is a purely subjective opinion based on the perception of human hearing, which can tolerate anything below 1% THD/IMD/Noise.

 

[johny_2000]

Take a look at the current measurements of the ADAM Audio D3V studio monitors:

Distortions:
All loudspeakers distort but do it more than others. Distortion is sound output produced by the loudspeaker that is not present at the input. Harmonic distortion is distortion that is a multiple frequency of the original signal, for example if the input signal is 100 Hz, the second harmonic is at 200 Hz, the third harmonic is at 300 Hz, etc. Higher order harmonics are typically produced at a lower level, so if the 2nd and 3rd order harmonics are low, the higher order harmonics will be increasingly inaudible. If all the harmonics are added together we have the total harmonic distortion (THD) which is, by definition, the highest line on the graph. Second order harmonic distortion is caused by asymmetries in the system and can sound quite warm and pleasing. Vinyl records and valve amplifiers generate a lot of this. Third order harmonic distortion is caused by clipping in the system and never sounds good. Amplifiers played too loud or drivers reaching their maximum excursion suffer from this. Clearly all forms of distortion should be minimised in a studio monitor which has the task to accurately reproduce the input signal and add no extra content to that signal. It is possible to have a high THD and have a nice sounding product if the THD is dominated by second order harmonic distortion, therefore THD on its own is not a good indicator of audio quality. As the output level is increased the distortion also increases and eventually, if loud enough, all the audio from the loudspeaker can be distortion (0 dB = 100% on the graph) but the loudspeaker should already be strongly limited by the protection system well before this. Note that -20 dB = 10%, -30 dB = 3%, -40 dB = 1%, -50 dB = 0.3%, etc.

 

[JSmith]

If one has harmonic distortion, there then is also generally intermodulation distortion. The latter is rather nasty and quite audible when it gets high enough.

What people may hear with some tube amps is usually FR variations, rather than 2nd harmonic distortion.

There are other ways of experimenting with harmonic distortions levels, without it being baked into a device.


JSmith

 

[johny_2000]

@JSmith
What tube amps have you listened to?

 

[johny_2000]

Coming soon...
We'll see 1kHz THD+Noise and 32-tone IMD distortion, as well as Frequency Response graphs.
Stay tuned!

 

[amirm]

Look forward to it....

 

[johny_2000]

The MHA200 arrived today. I only had time to unpack it and set up all the cables and controls.

Did a quick listening test with a few well-known music tracks.
I've already found some pros and cons of the device, but I'll put them together in the next few days and post them here.

 

[Doodski]

The MHA200 arrived today. I only had time to unpack it and set up all the cables and controls.

View attachment 400978

Did a quick listening test with a few well-known music tracks.
I've already found some pros and cons of the device, but I'll put them together in the next few days and post them here.

It's a wonderful typical McIntosh but I think the layout for display purposes should include the tubes being at the front and the transformers at the rear.

 

[johny_2000]

It seems to me that the audio path is purely vacuum tubes and transformers, but there is a piece of reality with a microcontroller from the former ATMEL company (now Microchip).
On the motherboard, you can see an ATmega32U4 with a USB-B port.

Sorry for the image quality. It's hard to focus through the grid on the back cover.

Based on the chip specifications:
- High-performance low-power 8-bit AVR® microcontroller
- 16/32 KB of in-system self-programmable flash memory
- USB 2.0 Full-speed module
- 12-channel 10-bit ADC (Differential Channels with Programmable Gain)

I can conclude that this is a signal detection and power management processor with a possible firmware update by the company.

 

[Tom C]

For someone seeking a connection to the past, well, yeah, tubes are a connection to the past. But it costs more to do it with tubes. And the very best solid state performs better. So, if you got money to burn, knock yourself out. But if you’re like the rest of us, every dollar counts, so don’t spend what you don’t have to, if there’s no percentage in it.

 

[johny_2000]

Okay, let's start with the traditional 1kHz Distortion Panel.
Amplifier: McIntosh MHA200

Related device specifications from the manufacturer:

• Total Harmonic Distortion 0.5% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20kHz
  <0.20% at 1W, 20Hz to 20kHz
• Signal To Noise Ratio 94dB

Test conditions:
Input: 2Vrms; Output: 2Vrms; Load: 300 Ohm.
All connections are balanced.

The results obtained at unity gain and 300 Ohm load meet or exceed those specified by the manufacturer:
THD+N = -67 dB (0.044%), which is SINAD 67 dB.
SNR = 94 dB
Noise = -108 dB

However, it should be noted that there is a lot of noise coming from the power supply, modulated by harmonics from 60 Hz and above.

 

[GXAlan]

That seems reasonable for a tube amp, but how are you measuring it (and grounding it to the ADC?)

 

[johny_2000]

That seems reasonable for a tube amp, but how are you measuring it (and grounding it to the ADC?)

Thanks for the pertinent question!

I measured it with a balanced connection for one output channel going to an AES17 1kHz notch filter going to an isolated ADC with THD+N@-127dB and then digitized by a grounded PC with ASIO drivers, Multitone @ REW software.

Notes: The MHA200 is not a grounded device by manufacturer's choice. It uses a two-wire power cord.