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|19th September 2003, 03:12 AM||#22|
Bad Storm you having there - Isabel
I hope that you and your familly are safe at the moment with Isabel raging at your door.
|19th September 2003, 05:12 PM||#23|
My two preamp PCB work the first time I tried them
So I guest I have just to start building the enclosure.
I hope these results can help you complete your ONO.
Here My measurements:
MC Gain ONO Specs (1Khz)
J1-J2 IN: 70.3 dB 71dB
J1 (+4dB) +4.6dB
J2 (+10dB) +7.3dB 170BL type current too high, I'll keep J2 ON.
MM Gain ONO Specs (1Khz)
48.3 dB (No coupling Cap) 40dB
Vout MAX: 17.7Vrms (no clipping) 20V (1% clipping)
Vout MAX (Balanced) 35.4Vrms 40V
Zout: 250 ohms 300 ohms
DC Coupled (No coupling Caps), Output Vdc out, < 50 mv.
I still have to let the circuit stabilise to do the final adj.
RIAA Curve (Both PCB)
HZ dB My ONO (dB)
20 19.91 19.6
50 16.94 17.0
100 13.09 13.1
200 8.22 8.2
500 2.65 2.6
1K 0 (Ref) 0 (Ref)
2K -2.583 -2.7
5K -8.168 -8.1
10K -13.566 -13.6
20K -18.98 -19.4
50K -24.54 -25.6
PCB Voltages & Current Measurements:
24.8V (Schematic 26V)
11.6V (Schematic 15V), Q10-Q13 are 2SK170BL Type
Q15 drain: 11.9V
Q10-Q13 Is: 4.1, 4.2, 4.2, 4.1ma (PCB #1)
Q10-Q13 Is: 4.2, 4.3, 4.4, 4.4ma (PCB #2)
D5 Anode: -27.8V
R67-R53: 1.2V = 8ma Ie Q16,Q17
R64: 0.9V = 1.9ma Is Q19
R28: 0.35V, adjusted with R25
Output FETS are warm, not too hot.
|20th September 2003, 01:51 AM||#24|
The Concept of the ONO Enclosure
This is my concept for the enclosure that I want to build for my ONO preamp.
It will be a two boxes connected to a common vibration insulation plateform. The plateform will be made of 1 inch tickness laminated maple plank.
This plank will be suspended on 3 long spikes, solid brass plumb bob with steel tip.
Both boxes will be made with 1/8 aluminium sheet and 3/4X3/4 alu bar.
The 2 boxes will be connected to the plank. The preamp and regulated power supplies will be on top. The main input, the two shielded power transformers and the unregulated power supplies will be in the bottom enclosure.
The 40V voltages will only cross between both enclosure without using connector
A blue led will turn on on the supply module. The power switch will be on the back part of the Main socket.
Here the AutoCAD front view of the enclosure.
|23rd September 2003, 06:07 PM||#25|
Schematic with modifications
Here, the preamp card schematic with all the modifications, capacitors type, notes, etc...
|23rd September 2003, 07:37 PM||#26|
Your boards LOOK REALLy GREAT..!
what program you use.
i wish i could build boards like that.
i have so many projects i could finnish ..
I use ammonium persolfate to etch my boards. with a heater and pump also.
used a old fish tank pump and bubbles creator. and a fish-tank heater works perfectly..
what soft you use. ?
|23rd September 2003, 10:35 PM||#27|
I use eagle PCB and UtilBoard (which suck compare to Eagle).
The PCB you see for the ONO where desing by Ed Robinson. I used his own jpg pcb pictures to produced the PCB. However, I modified Ed version, bigger PSU traces and increased clearance for the gnd plane of the preamp PCB. I can send you a copy of the jpg I used.
Check my previous post, I explained in detail how I did my PCB.
|23rd September 2003, 10:38 PM||#28|
I know how to do pcb's ive done lots. ( etching that is. )
i want to build a few of my own. i think.. ill try a few of my own photo boards though.
Can you use ammonium persolfate though i wonder.. ?
|26th September 2003, 11:19 PM||#30|
ONO - The Dual transfo
Here the dual transfo that I choosed. They are from Hammond, dual - split bobbin design. Same kind of transfo desing used by YBA in their integrated. I have it also in my Bryston preamp that I like very much.
This transfo desing offer Low primary to secondary coupling, balanced windings, no electrostatic shield required and low EMF radiation due to semi-toroidal design.
In addition to that I installed a shield around the transfo windings using 3M EMI shielding cooper tape.
There is one transfo per channel (dual mono supply). The model closest to the needed specs was the 229D56, 2X28V, 0.857A
I got a nice +/-40V using it in this application.
Here a picture:
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