Modding the Entec 203.5 Dac
The aim was to raise the performance of this pint sized unit that already sounds pretty good. My budget was about £20 but ended up going a bit over it …that was the fault of the opamp I chose.
Opening the case its clear that the unit is reasonably well built with relatively good quality components.
The solder used was 4% silver lead free …so the label stated.
D1 and D2 caught my eye …..these are just standard 1n4001 rectifiers so out they came and in went a pair of 11QD10’s
C48 and C49 these are the reservoir caps not a make I recognise…so out they came and in went a pair of pannasonic fc [1200uf 63v ].
All the Muse caps are better than what I had to hand …so I left them alone apart from bypassing each with a 0.1uf 63v wima film cap. You need to be careful as there’s little room under the pcb so they need to be slim.
Next up came the opamp opa 2134 is pretty good in my book …..but there are newer units now out there. I desoldered the opamp and fitted a high quality turned pin socket. Looking through my stock of opamps I found a opa2227 so what the hell …lets try it
Looking at the signal path its clear there are not caps in the output .. hooking up my oscilloscope thought I saw a trace of dc …..that’s easy to sort I added a pair of 4uf 150v paper in oils these are the size of three Jacobs cream crackers …with the case work fitted I was able to just squeeze them in .
There are two anonymous resistors in the output these were swapped for the same value dale vishay rn55’s .
Then finally I removed the nasty pcb mounted rca sockets replacing them with bulkhead mount types ….these were then hard wired with silver in ptfe from the pcb.
The results are very good , it seems far more musical than before with a sense of ease to the sound that belies its budget.
Well worth the couple of hours work involved.
Again these are only suggestions I'm certain there are many other similar solutions.....get experimenting
The aim was to raise the performance of this pint sized unit that already sounds pretty good. My budget was about £20 but ended up going a bit over it …that was the fault of the opamp I chose.
Opening the case its clear that the unit is reasonably well built with relatively good quality components.
The solder used was 4% silver lead free …so the label stated.
D1 and D2 caught my eye …..these are just standard 1n4001 rectifiers so out they came and in went a pair of 11QD10’s
C48 and C49 these are the reservoir caps not a make I recognise…so out they came and in went a pair of pannasonic fc [1200uf 63v ].
All the Muse caps are better than what I had to hand …so I left them alone apart from bypassing each with a 0.1uf 63v wima film cap. You need to be careful as there’s little room under the pcb so they need to be slim.
Next up came the opamp opa 2134 is pretty good in my book …..but there are newer units now out there. I desoldered the opamp and fitted a high quality turned pin socket. Looking through my stock of opamps I found a opa2227 so what the hell …lets try it
Looking at the signal path its clear there are not caps in the output .. hooking up my oscilloscope thought I saw a trace of dc …..that’s easy to sort I added a pair of 4uf 150v paper in oils these are the size of three Jacobs cream crackers …with the case work fitted I was able to just squeeze them in .
There are two anonymous resistors in the output these were swapped for the same value dale vishay rn55’s .
Then finally I removed the nasty pcb mounted rca sockets replacing them with bulkhead mount types ….these were then hard wired with silver in ptfe from the pcb.
The results are very good , it seems far more musical than before with a sense of ease to the sound that belies its budget.
Well worth the couple of hours work involved.
Again these are only suggestions I'm certain there are many other similar solutions.....get experimenting
I am. Just awaiting feedback from Nigel (fellow Head-Fier / audiophile) in Liverpool (I posted out his chip yesterday).... as far as I'm concerned from initial auditions this is the chip. Tried it in the Graham Slee Solo and a few others and, yes YES 
...finally I went back to 2132.
I have a 2107 in it right now and it is warmer than the 2227, 2132 and the original 2134. Better detail than the 2123/4. Not as airy as the 2227. I have a JRC4556 I might play around with.
