Pro-Ject Mk II. Keep in mind that while the Pro-Ject has more parts in it than the Rega, it's case is half the size. Most of the Rega's ingides is air.Something I forgot to mention in my last post is that another way in which the build of the Head Box is superior to the EAR is that it uses a double sided board with massive ground and power planes. This means less noise, lower power supply impedance. It also allows the board designer to run direct, short traces from one section to another.
It's clear from looking at the design that the designer worked very hard to keep the audio signal paths optimized, and any radiated EMI from the power supply away from them as much as possible. This is why the power supply caps are crammed in the way they are, and also why there's a mix of 470uF 25V caps and 1,000 uF 16V in there as well. The latter I'm a little worried about, because they are filtering the 15V supply, which gives the caps only about 1V margin of error before they are rated to break down rapidly. A pair of 25 Volt caps would make me feel better about the durability of them. I'll see if I can find some miniatures that will fit.
Nice tweeks!
ReplyDeleteFor myself, I have in my Headbox II replaced the Opamp to Texas Instruments THS4032, and earthed the board to chassi with a 100 Ohm resistor.
Have let my friend tst it with his HD650 cans, and compared it to his Rega ear 90 that cost about for tims the Headbox II, and he find it nearly similar in sound and power. Note that I have not replaced any caps, but are curious to replace the power caps, but what should I replace?
Thinking of replace C4 and C5 1000 mF 16 V to a higher Voltage value, but can I even go at a highr value - around 2000 mF?
And should I even replace the C1,
C2, C3 and C7 470 mF 25 V caps, with a higher value - up to 1000 mF?
Note that I´m happy with the sound, and don´t want to change the sound signature with more bass.
I have also build a C´moy with AD8066 Opamp and also Grado RA-1 clone, but the Headbox beat this!
Best regards: Mikael
I agree in general that doing the same with less is a great principle, but thats not what happened here.
ReplyDeleteThe Rega and the Project use almost exactly the same design in the audio pathway. The extra parts in the ProJect headphone amp are in the power supply filtration, which is why it is a much quieter amplifier than the Rega, which lets significant amounts of power supply ripple make it through to the headphones and why I think the Rega is an over priced POS by comparison.