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SHD gain question 5 months 1 day ago #66058

  • JimSawbuck
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First I have the latest software and hardware updates and everything is working well

In the control module you can add gain to each channel, in this position I have added 9db of gain  I believe the total gain available in the SHD is 12 DB

My question is now about volume control,  Is the volume adding gain on top of the 9db   or is volume a different source all by its self

My Decware amp likes gain so looking to see how much I can send it from the SHD

I also have a Schitt Freya S ( non tube ) pre-amp, if I put that into the system what would be the recommendation as to gain and volume settings for the SHD

Thanks
 

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SHD gain question 5 months 1 day ago #66059

  • kevinkr
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The volume control provides only attenuation. You've added 9dB of gain that is applied to the signal regardless of the volume control setting. Note that boosting the gain does not increase the maximum output voltage the SHD is capable of outputting which is ~2Vrms into RCA outputs and 4Vrms into the balanced outputs.

I have a friend who has a Decware amplifier and has also complained about the low gain which seems to be causing system integration issues for a lot of people. He concluded he needed about 5Vrms to drive his amplifier to full output.

You a couple of options to get more output to drive the Decware amp, one would be to use line transformers to go from balanced SHD output to unbalanced input on the amp, the other option would be to use the Freya between the SHD and the amp, but you need to check the output capability of the Freya because this is only going to help if the Freya can drive the input of the amp to the levels required.

For use with an external pre-amp after the SHD I would probably set those gains back to 0dB. (I assume you will use the SHD as a streamer and analog/digital pre-amp, and the Freya just for a little extra gain.

It seems like Decware is out on a limb here designing amplifiers that are incapable with the standards that have applied for decades.

In a former life I designed a fairly large number of tube hifi amps and I always aimed for 700mVrms - 2Vrms input sensitivity for full output, depending on the application.

I used an SHD for nearly 5 years before switching to a new SHD Studio early this year since I use DSP based speaker management and mostly digital sources so was no longer using much of the analog I/O capability.

 

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SHD gain question 5 months 1 day ago #66062

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Thank You

So Gain is about signal strength and does not impact output voltage, which is what my Decware amp really wants

I am not good with anything electrical, so is there existing product that I could buy to meet my need of increase voltage via RCA cables

Hope I am asking the right question

 

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SHD gain question 5 months 23 hours ago #66063

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I would try the Freya first and see if some volume setting provides you with sufficient drive for the amplifier. I am not aware of anything off the shelf that meets your needs. Do you know a tech in your area who could perhaps help you with an appropriate hardware solution? What you may need is a buffer between the SHD and the amplifier, note that this is not a shortcoming of the SHD, but a consequence of Decware's decision to build amps with much lower than normal sensitivity.

 

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Last edit: by kevinkr.

SHD gain question 4 months 4 weeks ago #66084

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adding gain to the Minidsp shd  was positive for my sound stage was deeper and better defined @11db gain for mains and 9 db for subwoofer
also there seems to be more over all sound coming from my Decware amp with volume set about 70%,

Then using the Minidsp shd for volume control

I will install my Schit Frey S after the Minidsp shd  which add anothe 12 db of gain and see what happens. I will then use the Frey S for volume control with the amp set at the same 70%

all this stuff is a journey  sometimes fun, sometimes frustrating with hopefully enjoyment at the end

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SHD gain question 4 months 4 weeks ago #66092

  • Tony_J
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Adding gain to the inputs is OK as long as the input levels don't ever exceed the max for the input (2V unbalanced, 4V balanced). If they do, then the input's ADC will clip the excess, which will result in distortion. Similarly, if the internal processing within the miniDSP exceeds 0dB, then the DAC will clip any excess. So you do have to be a bit careful as to exactly what you are dealling with on the analogue inputs and how much of a boost you can get away with.

I did some experimentation a while back on a 2X4HD that seemed to indicate that there is internally a good deal of headroom due to the floating point processing used, so you can boost a signal internally above the notional 0dB level, but woe betide you if you fail to get the signal back to at-or-below 0dB before it reaces the DAC (or any digi outputs for that matter).
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SHD gain question 4 months 4 weeks ago #66098

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In my system I use Audirvana Studio on a Win10 PC sending its  signal to the MiniDSP SHD via the network connection. I Perceive this is my DAC in my system which then passes the signal to the area where I am adding gain.  From there it is passed via 75 ohm RCA to my Decware Amp.

Discussions within the Decware site indicates My Torrii Jr V2  ( push pull amp ) can handle up to 20 db of gain,

Based on these perceptions I have been playing with the gain settings.  The results have been in the area of sound stage and some better dynamics - so positive so far.

When I add the Freya S I will reduce SHD gain to say 7-8 as the Freya S can add 12 db of gain, volume control will be moved to the Freya S under this configuration

Your thought would be appreciated

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SHD gain question 4 months 4 weeks ago #66099

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As I indicated in my post earlier, be very careful when you add gain within the miniDSP. If you are feeding it with a digital signal, it is very likely that you have little or no headroom - I.e., there will be parts of that digital signal that are close to 0dB already. If the signal already contains passages where the level reaches a couple of dB below max volume, then adding (say) 8dB of boost within the miniDSP absolutely will result in clipping when that signal gets applied to the DAC or to the digital outputs.
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SHD gain question 4 months 4 weeks ago #66103

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If you are moving the gain control to the Freya, the SHD should be run with no supplemental gain and the volume set to a few dB (maybe -6dB) below 0dB depending on how much boost you have applied in Dirac or the PEQ. You do not ever want to allow the SHD to digital clip - sounds very bad and at high volumes levels might potentially pose a risk to your tweeters.

If OTOH you use the Freya just to provide a fixed amount of gain you can continue to use boost in the digital signal chain as long as the volume control setting does not clip the post volume control digital signal path.

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Last edit: by kevinkr.

SHD gain question 4 months 4 weeks ago #66104

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Ok   So Audirvana has a  software digital volume control which is not used and set at 0DB

My MinisDSP SHD should be set with no gain added and volume at 0DB

the signal is then sent to the Freya S where 12 DB will be added ( it is either 0 or 12 ) and volume will be controlled by the Freya S,

All of the above should then be a safe place to be. 

Thank You everyone    Enjoy the Music
 

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SHD gain question 4 months 4 weeks ago #66105

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I recommend you set the SHD volume to less than 0dB unless Dirac is off and you have no PEQ. You need to account for any boost applied by EQ and Dirac. I recommend -6dB, but more could be required.

Monitor output levels in the SHD using the console to be sure you have a few dB of headroom with worst case source material.
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Last edit: by kevinkr.

SHD gain question 4 months 4 weeks ago #66106

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I recently went thru a extensive REW and DRAC testing and did not like the results. My La Scala's in my room have a significant dip starting at 200htz bottoming at 300Htz and finished at 400htz. DIRAC had a tough time dealing with that and the finale results were different sounding but not to my liking. Also the highs were a bit much which is not untypical with Klipsch. DIRAC may have added some PEQ but I did not during the REW process.

So a cleared all settings back to factory and started to play with the PEQ settings alone and found a sound more to my liking ,bumping the 300 htz range which also seemed to tame the highs also

All this without the Freya S in the system

At that point I started adding gain in the control panel. The added gain enhanced the sound stage as well as the dynamics.

So that is where I am now. I also have an old Velodyne 15 inch sub  ( has its own 400 watt amp and volume control) which has a builtin at 85 htz  starting point. The Velodyne is run out of the MiniDSP SHD ports 3 and 4. I am not a big base head so it works form me

 

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SHD gain question 4 months 4 weeks ago #66107

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I found correcting the speaker's worst problems first and then doing a dirac calibration gives much better results than relying on Dirac to do it all. My system is rather complex and I have separate speaker management hardware with DSP that handles  2 x 3 crossover, time delay, and rudimentary PEQ for the main speakers. I use the SHD (studio) to manage crossover between the mains and subs, as well as for delay for the subs - no PEQ needed. I applied the room calibration after this. I did literally did hundreds of measurements using REW over the past year as I continued to change the system and room.

Dirac can give great results, but the learning curve is steep and mic technique counts for a lot. I have used both tight and normal imaging (9 and 13 measurements) and generally prefer the tight imaging option in my space. The latest versions of Dirac also allow you to add additional measurements as you wish. I have also found that moving the mic a bit and repeating the measurement if you had a particularly deep null or peak greatly improves the results. I have sometimes run the same measurement 3 or 4 times before I get a capture that seems reasonable to me. I have a difficult and cluttered small room with a system that is capable of playing below 20Hz and fairly large horns - not a receipt for great sound if you are not careful. Room treatment I have found to be mandatory.

After all of this I am very pleased with the results, engaging Dirac now results in an audible improvement rather than the reverse which was often the case in the past.

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SHD gain question 4 months 4 weeks ago #66116

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Now its time to test and document   While I like technology like REW and DIRAC I will probably stay with what sounds best to me.

From what you have said about Mic placement I will have to come up with a method of precise mic location - any ideas for this need

Thanks

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SHD gain question 4 months 3 weeks ago #66120

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Choose spots relatively close to the mic positions shown in the measurements window, the critical one is the very first one at the center of the listening position. I typically do measurements in a rectangle that is about 48 inches wide. The higher and lower measurements I do about a 12 inch above my ear height and about the same below. Dirac v3.6.6 will put up an unhappy icon if the measurements are bad, move the mic a little bit forward/back, in or out and try again. Look at the measurements it displays, if there are excessively large peaks or deep dips move the mic a few inches in any direction, repeat until you find the spot that gives you a good measurement. I can't be more specific, you are trying to do the measurement where there is no extreme peak or null. It has taken me almost 5 years to figure out my room, you just have to try slightly different spots and look for measurements that Dirac doesn't flag. I have been adding additional measurement spots chosen at random in the general listening area.

Try to identify specific trouble spots in the spectrum, and not that flat does not sound best, or even in many cases, good. Dirac will try to make a recommendation based on its default target curve, that is the starting point. I generally save that to one slot. Trouble areas in my system/room are generally in the 600Hz - 900Hz and about 1.5kHz - 4kHz - I fix some of this in PEQ. And I sometimes apply some correction in these regions in dirac too.

Some of this is personal taste, and a lot of it is just discovering how your room and system interact. Don't be afraid to experiment, it is an adventure.  Room treatment is I think as important as Dirac in correcting room behaviors. Measure your RT60 and intelligibility index, but in general most rooms need some help controlling mid and HF reflections.
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Last edit: by kevinkr.
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