Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Luckbad, Nov 4, 2015.
@borrego Did you ever get that Reference 5.32?
Yes. I did get my reference 5.32 mod. The previous owner has done the following mods:
20% higher wattage, 10% higher output voltage R-core transformer, resulting 10V (stock was about 5v) difference between the input/output of the all regulation circuits. More headroom to deal with voltage fluctuation.
Replacing fixed resistors with VR adjusters for the analog stages voltage regulator circuits. Now +/- rail voltage for the analog stage are exact matched. In stock form there was 0.7V difference between +/- rail
Replacing output buffer (affecting XLR and RCA outputs) transistors from K246/J103 to finely matched K170/J74 (old stocks from audio-gd). 4 output buffer capacitors are replaced with Panasonic caps. Resulting improved transparency for XLR/RCA outputs
Amanero USB input (done by audio-gd). audio-gd no longer has the MCU software code for the reference 5.32, thus they have to hard wire the input switcher trigger to the output of one leg of a logic IC, resulting a small pop sound preceding the 1st song play. This is the only glitch.
Then there are other minor mods like PCOCC wires and stainless steel screws.
And I also snipped the DAC output capacitors on the 4 CASS modules as described by audio-gd: http://www.audio-gd.com/Pro/dac/RE52/RE5.2EN_Use.htm. Those capacitors are redundant to make the DAC sounding warmer. There are already capacitors inside the CASS modules cover for DAC output.
The mods turn the reference 5.32 from the most "syrupy" audio-gd PCM1704 DAC, to one which is very neutral, transparent and dynamic.
The previously owner also told me exact +/- voltage to power the PCM1704 is essential to get rid of the "syrupy" bass of PCM1704. The PCM1704 chip draw 6 times more current at its - rail, than at its + rail. Thus if there is no individual VR adjusters for the voltage regulator outputs for the DAC digital stage, there will be no chance the +/- voltage for the PCM1704 can be exactly matched. Fortunately all audio-gd PCM1704 DAC has individual VRs for digital stages.
The previous owner sold the reference 5.32 mod to me, because he is building a new DAC with Reference 10 digital board and Reference 7.1 analogue boards.
I'm strongly considering picking up one of these. I like the flexibility for my bedroom "tv" system (useful inputs and outs to amp and speakers etc) but since the only headphone I care to spend significant time with is the HD650, how is the pairing with the HD650 in particular?
It's lovely with the HD650. I balanced my cables for maximum benefit. The Master-11 -> HD650 is my primary listening setup.
If you ever happen to be down in Orange County on a weekend, maybe I can let you check it out (I'm in Laguna Hills). Things are pretty hard to actually schedule right now because I'm crunching at work, though.
I never cross the Orange Curtain! j/k Thank you for the offer. I'm swamped as well right now. All of a sudden I have 10+ deals going on at once so definitely hectic.
My Roku 4 has an optical out, but I've never used it. I wonder how that would sound going into the M11?
I just sent out December invoices so maybe when one comes back paid I'll place an order.
I know next to nothing about Roku.
Hi , my NOS 11 pairing with the new Sennheiser HD 800 S sound sublime ! Thanks .
New DSP v7:
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