Best amplifier solution for simple DIY needs.

kenrhodes

  I have often wished that I could find a simple solution to my amplifier needs.
  In a perfect world my amplifier would be: Class AB, dive a 4 ohm load, have digital inputs, remote control, pre-amp in and out, subwoofer out, and be stereo, in a single housing.
  I have one amplifier that does all this... it also does too much. It is a Class AB, 7.1, 120 watt per channel, behemoth that gets so hot it puts my blue-ray player into protect mode. The remote NEEDS its own manual. Many of the menu options can only be accessed through the remote making setup clumsy. 
  What options do I have? DIY is an option, as well as store bought, or used. 

Thanks for the help.

dcibel

Outlaw RR2160 fits your criteria, as do a bunch of other products. Pick your favourite brand and look at their selection of stereo receivers.

dcibel

Have a look for a used HK990 A lower cost option could also be Emotiva TA-100.

You could also use any old stereo integrated amp with a DAC, depending on how firm you are on the whole "everything in one box" idea.

kenrhodes

  I've made a few bids on E-bay nothing yet. Any more great suggestions? Anyone own the TA-100? That is looking like a pretty good option right now.

ani_101

kenrhodes said:

  I've made a few bids on E-bay nothing yet. Any more great suggestions? Anyone own the TA-100? That is looking like a pretty good option right now.

I do and it is very nice, quite large and hefty too for a 100 watt amp - ih ave the DAC / Amp combo

The other one I like is the ELAC integrated, but i feel the emotiva has more head room, even through they are rated the same. The ELAC is a feather weight compared to the emotiva in both heft and size

kenrhodes

Ani have you ever used a mini dsp as your receiver/preamp? Does the minidspHD also add the noise that the minidsp does?
  Thanks.

ani_101

kenrhodes said:

Ani have you ever used a mini dsp as your receiver/preamp? Does the minidspHD also add the noise that the minidsp does?
  Thanks.

I used both the mini dsp and the mini dsp hd. Did not get the noise with either of them, though I feel the mini HD does a better job in the resolution, of course using the digital input

kenrhodes

  I bid on a lot of stereo receivers and didnt win any. Went ahead with the minidsp HD and remote. I hope this will help simplify the user interface on daily use. It should also open up some more control for room correction and subwoofer controll.
  Thanks for all the help.

Ed_Perkins

<warning - long post >

I think a lot of the “noise” problems people have with the miniDSP can be traced to not properly matching the gain of their different stages, especially with the standard 2X4 miniDSP.  But you need to pay attention with the 2X4 HD too.  The HD has a jumper selectable 2 Vrms or 4 Vrms max input section.  So you want your input signal to be either 2 or 4 V at maximum level to use the HD’s full range and maximize the SNR.   One way to do this is play a 0 dBFS signal and adjust the level until the HD input is either 2 or 4 V.  Then make sure you never exceed that setting. You can find all sorts of 0 dBFS tracks on the web.  1 KHz is a typical frequency, but cheaper DMMs are more accurate at 60 Hz. 

You also need to match the output stage if you’re using amps with fixed gains.  You want to calculate the desired maximum amp output and work backwards to determine the corresponding input voltage. For example, take the ubiquitous TPA 3316/3118 amps: ultra cheap and available everywhere. These chips are gain adjustable (20, 26, 32 or 36 dB) depending on resistor values connected to the chip.   These dB gains correspond to voltage gains of approximately 10X, 20X, 40X and 63X respectively.  These chips are typically listed at 50 W into 4 ohms (albeit @ 10% THD and using a 24V power supply) so I’ll use 50 W as the max output.  With a 4 ohm load 50 W corresponds to about 14 V.  Working backwards this corresponds to a maximum amp input of 1.4V (20 dB gain),   0.7V (26 dB gain), 0.35V (32 dB gain) and 0.22V (36 dB gain).

So here’s the problem: to use the most of the HD’s 2 Vrms output means the TPA3316 amp should be set to 20 dB gain.  Even then you’ll be losing about 3 dB in SNR.  But most of the chip amps come set to 32 or 36 dB gain.  For a 36 dB gain amp you’ll be limited to 0.22V and you’ll be losing almost 20 dB in SNR. 

And finally you have to pay attention to the gain of your processing inside the miniDSP.  Using your full input range means that the overall processing gain can’t be greater than 0 dB – any additional gain can result with ticks and pops as the signal is digitally clipped.  So if you want overall gain in the processing you have to reduce the maximum 0 dBFS input level by the same amount.  Siegfried Linkwitz used a 7 dB boost on his LXMini.  At this page (LINK) you can see his calculations on how that reduces the maximum input level. Note that he’s working with the standard 2X4 with a maximum of 0.9 Vrms (2.54 Vpp) inputs and outputs.

kenrhodes

Ed, thank you. I know post like that are long and hard to write. The information you gave me is very valuble. Thank you.