Bybee Music Rails - My Experience

[Magz]

I noticed the other Bybee Music Rail thread was shut down, so I'm starting a new one to relate my experience with them. I have just finished rebuilding the low-frequency equalizer unit for my Infinity RSIIb speakers. The EQ is responsible for boosting the bass below 100Hz and contouring the sound up to ~2kHz or so, and the stock unit is less than transparent, shall we say. I have done several stages of upgrades culminating in the current design, in which I have replaced the single-ended MOSFET source follower output stage with a DC-coupled OPA827 opamp based stage, changed out all the old caps and resistors, put in new pots, and redesigned the power supply, moving it off the main board.

The first picture below shows what it looks like now. MUCH more transparent and clean sounding in the present incarnation. Stock all the components were crowded onto the one blue PC board, power supply right next to EQ and output stages, so it really can't help but be better sounding.

In any case, as part of the power supply upgrade I added Bybee Music Rails on the +/- of the 18V split power supply, after the LM7818/7918 regulators- you can see them in the middle of the box on the RatShack perfboard. I took scope readings of the power going into and out of the Music Rails, and they do seem to clean up a lot of the 78xx/79xx noise as evidenced by the narrower trace on the scope (picture 2 is before the MRs, picture 3 is after, 5 mV and 1 mS per division, ). As for the sound, well the unit is extremely clean and direct now, but how much of that is due to the MRs is up for debate - I suppose lower noise is always a good thing, right?

Anyway, there's a little picture for you to chew on. Let the chewing begin!

[Magz]

By the way, I'd like to commend Bybee Labs for excellent customer service. During the build I ran into some issues with grounding and although it was not their responsibility to teach me the ins and outs of troubleshooting ground noise, one of their engineers (Scott) spent quite a bit of his time, on Saturday and Sunday, helping me think it through and resolve the issue.

So a hearty thank you to Scott and Bybee Labs!

[cliffforrest]

I must have missed something, but I didn't see any data.

An opinion, yes.

[john curl]

Yes, they work as a noise reducer, especially with regulators such as the 317-337 pair.

[Magz]

Originally Posted by cliffforrest

I must have missed something, but I didn't see any data.

An opinion, yes.

Post revised to change the word data to picture.

[jimj166]

I have heavily modified a music hall dac25.2 for a client of mine. Thought it would be a good final touch to install the 2amp music rails
on the +/- 15 volt rails. Well, I read a bunch of the info on their site and started with the positive one. Put the v-out of the music rail on the v+out
of the belleson 78xx regulator, put the v-in of the music rail on the input of the 78xx. My readout on the output of the regulator is now 18v instead of 15v.
Could someone tell me what I'm not doing correctly?

[john curl]

Something is definitely wrong. You have to get LESS voltage, not more, so something is miswired. For example, the Music rail should be connected to the OUTPUT of any regulator, not the input.

[jimj166]

Thanks for responding John. So do I connect the the music rail in series out of the output of the regulator, and then the ground obviously to ground?

[Magz]

Originally Posted by jimj166

I have heavily modified a music hall dac25.2 for a client of mine. Thought it would be a good final touch to install the 2amp music rails
on the +/- 15 volt rails. Well, I read a bunch of the info on their site and started with the positive one. Put the v-out of the music rail on the v+out
of the belleson 78xx regulator, put the v-in of the music rail on the input of the 78xx. My readout on the output of the regulator is now 18v instead of 15v.
Could someone tell me what I'm not doing correctly?

The Vout of the Belleson goes to the Vin of the Music Rail. The Vout of the Music Rail goes to the circuit you are powering. The Music Rail should drop the voltage by 0.5V if it is working properly. The two grounds can be wired together and then to the ground for the regulator.


By the way, I just put another Music Rail on the DC heater supply for my 2-box tube preamp (PS box connected to preamp box via umbilical). It decreased the ripple substantially, from ~5mV to undetectable on my oscilloscope. Higher frequency noise spikes apparent on the scope were also eliminated. The preamp has a simple rectifier-10KuF cap-LM317 circuit for the DC in a separate power supply box, I put the Rail in after the 317, with a 100uF, 35V cap across the input, just before the tubes in the preamp box. It turns out that my heater voltage had been at 6.78V when it should have been at 6.3V, so the MR voltage drop of 0.5V put me right on the money with the heater voltage - a bit of a happy coincidence!

.

[marce]

Are they active EMI filters? similar to http://cdn.vicorpower.com/documents/...r/ds_qpi3L.pdf