The All Purpose Advice Thread

Modi Multibit USB absolutely sucks. I wouldn't come to any firm conclusions about that DAC using the USB input (especially from a noisy computer source). Try using the spdif input, it is much better.

 

I have a question about volume control, specifically in regard to digital and analog volume control.

Unless I'm mistaken, analog volume control is what we're mostly familiar with, present in pure analog headphone amps/preamps/integrated amps. In this case, the volume knob is connected into a rotating volume potentiometer (or more commonly, volume pot). Companies like Alps or Penny + Giles are well known for their volume pots. Rotating the volume knob changes the resistance of the pot, which results in change in volume. Because of this, the volume knob of amps with analog volume control cannot be turned freely beyond 360 degrees, but are stuck between somewhere around 7 o'clock and 5 o'clock. In other words, you cannot turn it counterclockwise from the minimal volume position of 7 o'clock, or clockwise from the max volume position of 5 o'clock.

On the other hand, digital volume control basically controls the volume in the digital domain, usually via dithering. Such digital volume controls are common in many DAC/preamps or DACs with volume control, such as Soekris dac1541. Usually, the volume is represented as, for instance, -10 dB (with 0 dB being the maximum volume) on a screen. In these cases, the volume knob doesn't have to be stuck between 7 o'clock and 5 o'clock and could be rotated beyond 360 degrees in both directions, because the volume knob is not actually connected to a physical, analog resistor potentiometer inside that limits how much the volume could be turned. Of course, it would still be possible to fixate the volume knob so that it stays between 7 o'clock and 5 o'clock, but turning the volume knob would still change the volume digitally without any involvement of a potentiometer.

Now, while I don't mean to generalize, analog volume control is widely considered to be a better sounding method of volume control than digital volume control, although it would depend on the quality of the potentiometer too.

So here's my question... I recently purchased a McIntosh MA252, a hybrid integrated amp (tube preamp + SS power amp). McIntosh states that the MA252 is a purely analog amp with no digital circuitry (other than the digital display), unlike their other integrated amps that incorporate a built-in DAC. However, I realized that its volume knob could be rotated freely beyond 360 degrees in any direction. As such, there is no way to tell the volume by looking at the knob alone (there is no mark on the knob that tells what position it is in), the only way to tell is by looking at the display (which shows the volume from 0 to 100). If I turn the knob counterclockwise, the volume on the display decreases until it turns 0, but the knob could be turned further counterclockwise (although the volume will still remain 0). It became evident that this volume knob was not connected to a volume potentiometer inside.

So I emailed McIntosh, asking if the MA252 uses a digital volume control, which means volume is controlled in the digital domain. I still thought it was strange, because the MA252 was advertised as a pure analog amp without digital sections, and as such, it doesn't have any digital inputs to speak of. If the MA252 indeed had a digital volume control, it would have to have an AD converter inside that converts analog signal to digital, then the digital signal would be dithered by the volume control, and then it would have to undergo DA conversion again. As crazy as it may sound, there are actually amps that do this, such as Goldmund Metis 7 or its poor-man version JOB INT. Indeed, the volume knob of Metis 7/JOB INT are also freely rotating knobs that uses no volume potentiometer.

However, McIntosh replied that the amp is a pure analog amp, and that there is no AD or DA conversion happening inside or the volume being controlled/dithered in the digital domain. So I asked, "oh, so I suppose there is a volume pot inside the amp that controls the volume 'analogly', but in order to make the volume knob feel smoother, you didn't connect the knob physically to the pot, but instead the knob controls a mechanism that electronically rotates the volume pot inside, like how you're using a remote control (the MA252 does come with a remote control too, but using the remote control to control the volume doesn't make the volume knob spin). But, the answer was no.

I was told that many McIntosh amps, including much more expensive and higher-end integrated amps and standalone preamps, use a method of analog volume control that doesn't involve a volume pot. Instead, the volume is controlled via resistor chips, a method known as IC volume control. The volume is controlled in the analog domain, but not via a resistor pot.

So... have any of you had experience with amps that control volume in the analog domain, but don't use a pot? In theory, is this method better than the classic potentiometer method? I know some of you own or have used the MHA150, another headphone amp from McIntosh. Is the MHA150 volume knob also like that too?

 

I can't speak to the pros and cons of each method, but IC volume controls are actually pretty common and I suspect they vary in quality just as much as pots do. My mid-fi Yamaha AV receiver has a volume control knob that rotates freely, and of course it controls the volume even on analog sources so I assume it must use a similar method (it's certainly not doing A/D and then D/A just to control the volume).

 

@songmic you're over thinking.

Just a stepped attenuator that's not directly controlled, because that way you don't have to attach a servomotor if you want to use that same setup with a remote. *

Its also actually easier to do it this way if you're not building the stepped attenuator directly into a pot-like configuration.

A pcb attenuator is not by nature directly controlled, so it actually makes more sense to do it like mkintosh did, where its a relative position knob, than do an absolute position one like schiit did on the Ragnarok, Saga and Freya.

More sense from a keeping the engineering simple pov, anyway, the ergonomics is debatable.

* or have it become disconnected from the volume and do nothing sometimes until you turn it way down, again like schiit does.

Le edit: to multi-paraphrase @schiit, there is no dark conspiracy

 

Thanks for your input, it's just that I've never had experience with such analog amps that don't use a volume pot. Every amp I've owned used an absolute position volume knob/pot (e.g. Schiit, Eddie Current, DNA, Cavalli, ecp, Mjolnir, etc.) so I wasn't aware potless analog amps existed.

 

Sure.

If you build your relay or otherwise stepped resistor attenuator into a pcb, you can also just use an up and a down button, since at that point you have some kind of controlling circuit that turns a volume input into a specific set of resistors, so controlling that controller circuit with a pot, buttons, a touchscreen, eye tracking ... is just ergonomic and/or design choice.

They're are also other methods to do so, but I'm not qualified to talk about amp design that way

 

Hey peeps, I need some advice on pad rolling for the Audeze LCD2-Classic. Apologies if this was covered recently. Are the Dekoni pads the best option? If so, which one (sheepskin, fenestrated, hybrid, etc)? If any of them have a positive effect on the upper midrange dip that's a plus.

 

Dekoni Elite Velour is your best option outside of the OOP Audeze vegan pads. Helps reduce the upper mid suckout (at the expense of a little bit of subbass extension, a worthwhile tradeoff IMO)

 

I recommended a friend get some OPPO PM-3 headphones several years to use at work, and he’s loved them, but they’re worn out I guess and now discontinued.

What’s a good modern replacement for the PM-3 for work use? Over ear and comfortable being requirements

 

NAD HP-50, BUT he should try before buying because some (mainly those who've self-reported as having bigger ears and/or heads) have found fit & comfort problematic.

They're not planar, but have bass that's well done and is prominent, but not to the detriment of the rest of the range.

 

Hi guys,
So a couple months ago I purchased a pair of Beyerdynamic DT 1770 pros, and have been running them with my Macbook Pro 2017 (no touchbar). I think the sound quality is great, and I usually listen at half volume what my mac is able to deliver. I'm curious to know whether a dedicated DAC and Amp would improve the sound quality with my current setup, since I've heard Apple does a good job with their built-in soundcards (Cirrus Logic, apparently). Does anyone have a similar setup, with previous experience?

The JDS Labs Element looks really tempting for a future upgrade. Alternatively, I might just get the JDS Labs El Amp, and run it with the mac's onboard DAC. But this hinges on my assumption a standalone amp will somehow improve sound quality at that same listening volume. Any advice would be greatly appreciated!

 

What is a inexpensive good usb to spidf converter?

 

What’s inexpensive? Schiit Eitr is the typical recommendation around these parts in the under $200 range.

 

That was a major brain fart. Completely forgot about the Eitr. Thanks!

 

I'm looking for recommendation for a USB DAC for my desktop, but my budget is around $125. It could be an Amp/DAC combo, doesn't matter I just need to go from my computer to my Paradigm PW AMP which arrives soon to replace a Klipsch Powergate witch has to go back. The PW-Amp has analog RCA input, it'll be driving NHT SuperOne and a small sub. My first thought was either a used Modi 2 UBER or a new Modi 3, is one clearly better than the other? Are there better options out there for the same money? I listen to a broad mix but really enjoy modern big band jazz, and some classical (former musician). Thanks, let me know if I tripped over any written/unwritten rules so far.

 

Modi 3. It has really better transients and not as polite as other dacs with the same chip (ak4490).

 

I've had a Modi 2 Uber for a few years and picked up a Modi 3 a couple months ago. To me the biggest difference is the M3 is smoother in the treble and a bit warmer. The M2U tends to be a bit sharper. I like both but I think the M3 has better synergy with my Paradigm Studio 10s. While not your setup if the NHT are neutral to bright I'd lean that way. But if you are enjoy treble or perceived sharpness, try the M2U.

 

Awesome, thanks guys. I have a love/hate relationship with sharpness and treble. I crave realism in the ride cymbal & hi-hat for instance, but I can't abide sibilance and harshness. Not impossible but hard to find headphones that fill the bill on a budget.
Modi 3 it'll be then. Unless there's something else i should look at around $150.

 

Ok, so I just learned that the Audeze LCD-2C pads are essentially glued on. How much damage will the pads incur in removing them? Can they be reinstalled somehow? I'm nervous that I won't like the result of swapping them for the Dekoni, and want to go back.

 

I can't speak from experience with the protein leather pads on the LCD-2C, but with the vegan and lambskin LCD-2 pads it depended on the age of the pads - newer pads could be carefully removed without damage, but older ones tended to tear no matter how careful I was. Fully intact pads can easily be reinstalled (Audeze support can supply you with additional adhesive rings) but torn ones won't stick back on as well.

Maybe another LCD-2C owner can chime in.