Silvas
Well-known member
Hello
What a nice compressor. Since the beginning, i wanted to turn it into a "mastering" compressor.
It has all kubi mods, but the output cap is not as big. I used a 22u solen fast.
Input and output transformers are Edcor XSM. 600:10K for the input and 15k:600 for the output. I ran a sweep while watching Waves PAZ, and it´s quite flat up to 20K (+-1dB). Need to do more adequate freq. response tests.
The power trafo, well, it is an Antek 1T250. It is working quite well, with some drawbacks. I stole AC from the heaters secondary to feed PSU3. No problems with that yet. PSU3 is 5V. 7805 is a bit hot, 14 volts at the input.
This trafo has 2x 6.3VAC + 2x 250VAC secondaries. the 250VAC secondaries are wired in paralell. I ended up with a bit high voltage, but after adjusting the voltage resistors on the TL783, i have 247VDC after the HV resistors. Close enough. With the 6.3VAC secondaries in paralell, the rectified voltage is way too low for the heaters reg...And with the 6.3VAC secondaries in series, the voltage is way too high...so, i used a LM338K, mounted on a quite big heatsink. Voltage before regulator is around 14 volts DC. Regulating that down to 6.3V generates LOTS of heat. Even with the big heatsink, the regulator was running too close to its thermal limit (had the thing on for a whole week with no thermal shutdown). I had two ideas : 1) put a power resistor before the regulator and 2) put a fan on the heatsink. I tried (1) but the power resistor was just before the reg input and after the filter caps (bad place i think) so heaters DC voltage was unstable (but the reg was quite cool and the resistor was quite hot). I wanted to try the power resistor right after the diode bridge but didn´t want to cut anything so...i ended up using a computer fan, fastened to the heatsink and the regulator is now happy. The fan is running on the +5V PSU3 and it´s quiet.
Anyway, the beast is running smoothly.
The meters are Nissei. Changed the LED´s for blue LED´s and love it. It´s a nice contrast from all that warm VU´s on the studio. The relay boards? The original relay boards (4 boards, for D-AOC and PM670) were stolen from my car (along with LOTS of parts). So i did a quick layout in eagle and etched them. They work as expected. If anyone wants the layout, please PM or email me.
All controls are 24pos rotary switches, the uraltone ones. Knobs are Davies 1919.
Front panel is laser engraved as on my D-LA2A. Case is also the same.
The sound ? Love it. Invisible compression unless you start to compress more than 12-15dB´s. Super smooth. Just what i needed for my mastering duties. Even with the edcor input iron. I´m going Lundahl input tx in the future. But for now, i´m happy. Love it on lead vocals and the 2-buss. Nice even when the input is driven hard. Very quiet, btw. Even with input and output full open, the noise is reading -78dBFS (0VU = -14dBFS at my interfaces).
I have a few questions for all you D-AOC gurus out there :
I have a small level mismatch between channels, 0,7dB. And the rotary switches are tracking levels perfectly between channels. I want to fine tweak the output level. Which will be the best place to do so? i don´t think i can live with that level mismatch.
And...the stereo link. Stereo link is working...but matching between channels is not so good when linked (perfect when unlinked). Is there any way of doing "stereo adjust" like in the LA2A ? for now, i´m going unlinked.
Thanks Rowan and Volker for an incredible project ! Had a great time building it. And kubi for the nice mod recipe.
Now, the pics : (crappy camera, sorry)
What a nice compressor. Since the beginning, i wanted to turn it into a "mastering" compressor.
It has all kubi mods, but the output cap is not as big. I used a 22u solen fast.
Input and output transformers are Edcor XSM. 600:10K for the input and 15k:600 for the output. I ran a sweep while watching Waves PAZ, and it´s quite flat up to 20K (+-1dB). Need to do more adequate freq. response tests.
The power trafo, well, it is an Antek 1T250. It is working quite well, with some drawbacks. I stole AC from the heaters secondary to feed PSU3. No problems with that yet. PSU3 is 5V. 7805 is a bit hot, 14 volts at the input.
This trafo has 2x 6.3VAC + 2x 250VAC secondaries. the 250VAC secondaries are wired in paralell. I ended up with a bit high voltage, but after adjusting the voltage resistors on the TL783, i have 247VDC after the HV resistors. Close enough. With the 6.3VAC secondaries in paralell, the rectified voltage is way too low for the heaters reg...And with the 6.3VAC secondaries in series, the voltage is way too high...so, i used a LM338K, mounted on a quite big heatsink. Voltage before regulator is around 14 volts DC. Regulating that down to 6.3V generates LOTS of heat. Even with the big heatsink, the regulator was running too close to its thermal limit (had the thing on for a whole week with no thermal shutdown). I had two ideas : 1) put a power resistor before the regulator and 2) put a fan on the heatsink. I tried (1) but the power resistor was just before the reg input and after the filter caps (bad place i think) so heaters DC voltage was unstable (but the reg was quite cool and the resistor was quite hot). I wanted to try the power resistor right after the diode bridge but didn´t want to cut anything so...i ended up using a computer fan, fastened to the heatsink and the regulator is now happy. The fan is running on the +5V PSU3 and it´s quiet.
Anyway, the beast is running smoothly.
The meters are Nissei. Changed the LED´s for blue LED´s and love it. It´s a nice contrast from all that warm VU´s on the studio. The relay boards? The original relay boards (4 boards, for D-AOC and PM670) were stolen from my car (along with LOTS of parts). So i did a quick layout in eagle and etched them. They work as expected. If anyone wants the layout, please PM or email me.
All controls are 24pos rotary switches, the uraltone ones. Knobs are Davies 1919.
Front panel is laser engraved as on my D-LA2A. Case is also the same.
The sound ? Love it. Invisible compression unless you start to compress more than 12-15dB´s. Super smooth. Just what i needed for my mastering duties. Even with the edcor input iron. I´m going Lundahl input tx in the future. But for now, i´m happy. Love it on lead vocals and the 2-buss. Nice even when the input is driven hard. Very quiet, btw. Even with input and output full open, the noise is reading -78dBFS (0VU = -14dBFS at my interfaces).
I have a few questions for all you D-AOC gurus out there :
I have a small level mismatch between channels, 0,7dB. And the rotary switches are tracking levels perfectly between channels. I want to fine tweak the output level. Which will be the best place to do so? i don´t think i can live with that level mismatch.
And...the stereo link. Stereo link is working...but matching between channels is not so good when linked (perfect when unlinked). Is there any way of doing "stereo adjust" like in the LA2A ? for now, i´m going unlinked.
Thanks Rowan and Volker for an incredible project ! Had a great time building it. And kubi for the nice mod recipe.
Now, the pics : (crappy camera, sorry)
![[silent:arts]](https://cdn.imagearchive.com/groupdiy/data/avatars/m/0/172.jpg?1620371656){kind=avatar}
