Mezmerize DCB1 Building Thread - Page 107 - diyAudio
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Old 30th October 2013, 06:39 AM   #1061
henryve is offline henryve  South Africa
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Hi

I have just ordered the Delta 1 + 2 and LCDuino for my Aikido, but will also use it for my DCB1. If you are concerned that DC fluctuations will interfere with the relay operations then you should connect the relay coils to a separate DC supply. AMB has provided for this. This also means you may use 12V relays in place of 4.5V relays. They explain how to do this in their documentation on their site. The only proviso is that the DC voltage must be .5V above the relay coil operating voltage.
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Old 30th October 2013, 07:08 AM   #1062
emyeuoi is offline emyeuoi  Italy
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Hi Henryve and thank for your reply. At the end I have come to your own conclusion using a dedicate PSU at 12V. I hope that a new transformer in the same case of DCB1 doesn't generate any hum... as of now the DCB1 is absolutely silent and fantastic sounding.
I will prepare a new front panel for the LCD and the motorized pot and I will interface the delta 2 with the same connector for the switch. Actually having the remote control and the LCD is intriguing but if the LCDuino will decrease the performance will be easy to back to the original.
Regards
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Old 30th October 2013, 08:09 AM   #1063
henryve is offline henryve  South Africa
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Quote:
Originally Posted by emyeuoi View Post
Hi Henryve and thank for your reply. At the end I have come to your own conclusion using a dedicate PSU at 12V. I hope that a new transformer in the same case of DCB1 doesn't generate any hum... as of now the DCB1 is absolutely silent and fantastic sounding.
I will prepare a new front panel for the LCD and the motorized pot and I will interface the delta 2 with the same connector for the switch. Actually having the remote control and the LCD is intriguing but if the LCDuino will decrease the performance will be easy to back to the original.
Regards
Firstly: I think you actually need the LCDuino to control the Delta 1 and 2. Or else you have to develop your own way to control the Delta 1 and 2.

Secondly: You don't need big transformers (so no hum really) for the LCDuino PSU and the 12V for the relays. In fact, you could use the DCB1's transformer (15V) for the relays and pass it to a standard programmable voltage regulator. I am lazy, so I am just using their PSU also for the LCDuino setup with the 4.5V relays. It uses a small PCB transformer.
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Old 30th October 2013, 08:34 AM   #1064
emyeuoi is offline emyeuoi  Italy
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Sorry... I was not clear on my description... I will have (is on the way) the LCDuino and the relevant delta 1, the delta 2 for the switching of the 6 input of the mesmerize board and the motorized pot. Plus the dedicate delta 25 for the 5 PSU with a small PCB trafo. About the hum I am just a little scare adding another trafo in my actual pre... but we will see.
Thanks for your replies... appreciate! I will let you know...
Enrico
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Old 2nd November 2013, 12:59 PM   #1065
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And another DCB1 Mezmerize has come to life!

A few comments on my build:
  • The smoothing caps are Panasonic FC 2200uF 50V, I piggybacked two together to get close to the recommended 4700uF. The CCS resistors are 10R 5W thick film, so we're dealing with a moderate hotrod version here. The resistors in the signal path and for the regulator portion are Dale RN55D, caps are Nichicon Muse, expect for the LED string caps, they're some 0u47 Panasonic PP film caps. FETs are IRFP(9)140N, diodes are SF16. The 4 2SK170 JFETs for the buffer were all somewhere around 7.5mA IDSS, the others in the reg somewhere around 8mA.
    The heatsinks are way oversized, but hey, why not.
  • As I've mentioned earlier in this post, I'm using 221R gate stoppers (instead of 470R), and judging from what I'm seeing on my 20MHz analogue scope, it's not a problem (no oscillation) to use such a small value.
  • Since I am pairing this Mez with a DCB1 blue edition (Hypnotize), which in turn is fed into and supplying a DCB1 style crossover, I have placed the volume control between the Mezmerize and the Hypnotize. At the Mez's input, instead of the pot, I have placed 22.1k Dale RN60D resistors from signal to ground, which in parallel with the buffer should form an input impedance of pretty much 20k. I have the impression that my source (DAC) likes the fixed resistance better than it did like the direct volume pot before.
  • The source selector I took from my old BOZ build, and since I'm only using four inputs, I spliced the indicator LED's onboard supply into the ribbon cable to remotely power a LED which is indicating the selected input (LED's ground is individually switched through together with relay).

Here are some Numbers that I've pulled from the circuit when I was testing it with a DC benchtop supply:

+V_supply=18.09V -V_supply=-18.13V (from DC supply)
+V_10R_drop=1.35V +V_10R_drop=1.43V (divide by 10R to get current in A)
+P_10R=182mW -P_10R=204mW (dissipation of CCS resistors)
+V_reg=10.23V -V_reg=-9.49V (regulator supply voltage)
+V_3LED=5.42V +V_5LED=9.60V -V_3LED=5.45V -V_5LED=8.85V (voltage drop over LED chains)
V_output_L=1.1mV V_output_R=-1.9mV (DC output offset)

So far my build is looking good, noise free, well tempered, and it sounds very transparent.
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File Type: jpg 20131102_120446.jpg (696.7 KB, 349 views)
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Last edited by Rodeodave; 2nd November 2013 at 01:04 PM. Reason: typos
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Old 2nd November 2013, 02:51 PM   #1066
Tea-Bag is offline Tea-Bag  United States
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Nice clean work RodeoDave. Spiffy.
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Old 2nd November 2013, 07:33 PM   #1067
Salas is offline Salas  Greece
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Ditto.
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Old 9th November 2013, 11:18 AM   #1068
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The first time I participate in this forum. DCB1 I almost made​​, but I need advice. I have 3 sets of 4 mached JFET: 7.1mA, 7.0mA and 6.95mA. Please where is the optimal use of each kit.

Thanks, Matjaz
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Old 9th November 2013, 07:52 PM   #1069
Salas is offline Salas  Greece
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Here.
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Old 9th November 2013, 09:47 PM   #1070
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Thanks, Salas.
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