volume level

Let me recite a bit of background before I get to the issue at hand:

I have a stereo setup that uses a MiniDSP digital crossover driving a biamped setup into a set of Klipsch cornerhorns. This is a very sensitive (1w gives 105 dB) setup and a few watts will shake windows, a bit more will take pictures from walls.

I have used this arrangement for years, front ended by an old school analog preamplifier which sourced a CD player, FM tuner, reel to reel deck and a turntable.

The CD player quit, and this, together with the advent of a decent RPi-based music player has moved me to replace the main source of music content with an RPi-based system. I use a Hifiberry Digi+, because I can drive digital to the MiniDSP, and save conversion of analog till the last possible moment: right at the amps.

Here’s the issue:

I found that the MiniDSP, when configured in analog input mode (to accept the line level analog output of my preamplifier) would enable me to play as loudly as I had before, when the system was ALL analog.

The move to digital direct drive:

When I went RPi and Volumio, I chose the Hifiberry Digi+ because it had toslink and SPDIF, and was reputed to have outstandingly low jitter.

However, I find that the resulting system, while it sounds quite good (and I find a clearly noticeable difference in quality, especially in the bass region, by using SPDIF vs. Toslink- go figure), this system does not play as loud as before. Not nearly as loud. I have the MiniDSP set for full on input, and I have the Volumio set for 100%, and while this is loud, it is simply light years away from what this same system was able to do before. Musical impressions are that, in general, then quality is very high, and the noise floor as low as I have ever heard it (and with an all horn system, if there’s noise anywhere in the chain, I hear it). But the dynamics seem to be a bit compressed. I correlate this with a much lower overall volume ceiling.

I am going to post this on the MiniDSP forum, too, to see if I have missed a setup parameter somewhere, either in the MiniDSP or the Volumio.

Any feedback would be welcome!!

Don’t know your Dsp, but have you tried to change volume with alsamixer ? For that connect via ssh to your PI and type “alsamixer” and try to change (increase or reduce Master volume). If no volume mixer is available in alsamixer, it’s because your DAC doesn’t support hardware mixer . Sorry if you already test it…

Thanks for the tip- I will try this. I am using a Hifiberry Digit+, which I believe is supported.

Have run alsamixer, and the sound card is correctly selected as hifiberry digi+. I can’t seem to figure out how to control this with alsamixer. Not much seems adjustable other than card selection.

That is as I might expect, though, since the digi is a digital output feed, and is not like a DAC where one might have control over the conversion characteristics like volume.

Still puzzling here.

Sounds like a fantastic hifi system.

I assume the biamp is a small tube amp for left/right channel or is it a bass and non-bass biamp?

I’d find the sweet spot in the biamp volume giving the best dynamic response and vary output from HiFiBerry DAC for volume control.

Running a pair of old Bozaks with just a rpi2-HifiberryAmp+ running only 25watts. Sound is amazing like the old SET amp days.

Love to hear your Klipschorns thru an Amp+.


This system is biamped, and I use (2) 100 watt monoblock MOSFET amps of English design for the bass, and I built a Decware SET tube amp for the top end (can do maybe 5 watts on a good day). The bass is a Speakerlab clone of the Klipsch corner horn, but this has been further modified: I have opened the throat up to Klipsch’s original design, and matched this with a very high motor strength woofer (as Klipsch used in the 50’s and early 60’s designs). I have also enclosed the rear of this horn to make it less prone to sealing difficulties in the corner.

The top end is completely different from an OEM Klipschorn: I have replaced the original midrange and tweeter horns with EV HR6040 Constant Directivity horns, of the original generation that started the trend toward CD horns in the late 70’s. These are driven by a pair of Altec 288’s.

I use the MiniDSP with this setup because the only practical way to make use of CD horns is to go active, so that you can add the CD compensation. I also use the Le Cleach crossover topology. This permits to cross the bass unit out at 300 Hz and therefore sidestep a traditional sort spot of the Klipsch bass horn (it has a checkered history with making it to 400 Hz). The MiniDSP also permits to time align the drivers. What results is an all horn system that actually images, and images quite well: the time alignment together with a more stable polar radiation pattern from the CD-based top end combine to make this quite enjoyable. The goal has been to take a time-honored system and update it to address the compromises that had to made due to technical limitations of the age.

I agree on your idea to center up the volume, however, I am using the Hifiberry Digi+ and NOT the Dac, as I am trying to keep everything all digital until the signals have to go to the amps. So the Volumio is feeding a digital stream over SPDIF to the front end of the MiniDSP, and that unit does its thing, finishing with conversion to analog at the outputs, headed for the amps. AFAIK, that digital feed is at 0 dB, and occupies all the bits when the hardware mixer is selected and/or when the Volumio volume control is set to 100. That’s where I want it, regardless- full information content headed to the crossover.

The only volume adjustment is on the MiniDSP, and this adjusts the output DAC ceiling. I don’t use the software-based mixer on the Volumio side, keeping it fixed to hardware, and 100% volume.

This is what I am struggling with, though: when I ran analog into the MiniDSP, I could play this system to thunderous levels, just as I always have been able, prior to going (analog in) biamp with the MiniDSP. But when I switched this over to a fully digital input, I seem to have lost that ability. I can get loud, but not fearsomely so. It’s not that I play it loud, really; I want to be able to do it because it represents the available dynamic range or headroom, and THAT is a signature of all horn speakers- they are razor sharp on transients and have tremendous dynamic range. I am trying to locate that lost dynamic range!

I do like what the RPi, a clean SPDIF output and volumio can do, though- once I get that range matter settled, I think this is going to become my new reference playback approach.


What an amazing loudspeaker and audio system! It is god-like.

I am trying to follow your system’s signal path and it is non-trivial.

My pure guess is you may wish to look at mpd volume control methods. I had to set volume control in a unique way for the HiFiberry digital Amp+ for volume control. By default, hardware volume control won’t work. Do enable this, edit /etc/mpd.conf. Have you tried this approach?

hifiberry.com/2014/12/guide … ry-ampamp/

Right now I am trying to get a Griffin powermate volume knob to control mpd. Have allot of issues trying to get the program evrouter to install on the rpi2 !?! Any help would be appreciated.

evrouter code is here.