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Mezmerize B1 Buffer Preamp
Mezmerize B1 Buffer Preamp
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Old 27th December 2018, 01:51 AM   #281
HatlessChimp is offline HatlessChimp
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Quote:
Originally Posted by batty View Post
Now it seems that the Relays are obsolete... I'm seriously giving up on this one.
Are they really damn! I bought the toroidal already. Hopefully I can use it on something else.
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Old 27th December 2018, 02:39 AM   #282
Salas is offline Salas  Greece
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Mezmerize B1 Buffer Preamp
Quote:
Originally Posted by batty View Post
Now it seems that the Relays are obsolete... I'm seriously giving up on this one.


Mouser has 2.582 KEMET/NEC EA2-12NJ or 3.298 EA2-12NU relays able to dispatch immediately. DigiKey has 4.257. The Fujitsu/Takamisawa A-12W-K is again stocked in the thousands. All those are listed as interchangeable in the BOM and carried also by RS Element14 SOS TME etc.
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Old 27th December 2018, 03:31 AM   #283
HatlessChimp is offline HatlessChimp
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Quote:
Originally Posted by Salas View Post


Mouser has 2.582 KEMET/NEC EA2-12NJ or 3.298 EA2-12NU relays able to dispatch immediately. DigiKey has 4.257. The Fujitsu/Takamisawa A-12W-K is again stocked in the thousands. All those are listed as interchangeable in the BOM and carried also by RS Element14 SOS TME etc.
Well done Salas. I checked a few weeks ago and seen the kemet also.

Cheers
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Old 27th December 2018, 07:09 AM   #284
batty is offline batty  Australia
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I must have the wrong BOM then.

Found the 2018 BOM, all is clear.
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I have gone from 85 watts class AB amplification to an ACA.

Last edited by batty; 27th December 2018 at 07:12 AM.
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Old 27th December 2018, 07:46 PM   #285
gwolfman is offline gwolfman
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Quote:
Originally Posted by Salas View Post
Orange ones* glow as nicely and in stock so the red LEDs saboteur failed to stop us.

*WP2773ND
Salas. I contacted the manufacturer and they recommended these:
WP144IDT

Will they work as well? It appears to just be a different shape (from all I can tell).
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Old 27th December 2018, 08:12 PM   #286
gwolfman is offline gwolfman
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Question LED Indicator Power Button

All. I'm wanting to add a switch with a blue LED power indicator {this is a Pass design after all }. It looks like I can find one that requires a 12V power source. Can I tap into the Mezmerize board someone and pull the 12V to have the 12V power source when powered up? I'm looking at possibly one of these three:
I'm new, so please forgive me. But it looks like there's a 10V source after C2 (according to the schematic). Can I pull the positive off of there and ground it on the otherside of C2? Or is there somewhere else more convenient and/or available?

Is the 10V enough or can I get 12V somewhere else? Seems like 12V might exist somewhere since I'm coming from a 15V transformer. Maybe somewhere around the 12V regulators?

Also, will I need a resistor? It looks like, according to the switch schematics, that only the TE switch has an inline resistor, so will I need to add one if I go with one of the other two options? If so, just calculate it off the max current for the LED and my supply voltage?

Also, I believe I'll meet the current and power requirements (since I'll be switching 120VAC; I just used the recommended 1.25A fuse as a guide), but if anyone can verify I'd greatly appreciate it.

Lastly, does anyone recommend any of the brands over the other? What about any other options/possibilities?

Thanks!
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Old 28th December 2018, 12:08 AM   #287
Salas is offline Salas  Greece
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Mezmerize B1 Buffer Preamp
The PWR LED pads on the Mezmerize board* provide for a power indicator LED. There, a 12V source (LM7812) outputs through a 2.2K resistor on the circular anode pad and the square one is ground for cathode. You can either alter the resistor's value for different brightness or use a link instead when there's a resistor in the switch for its LED already.

*Image crop showing the PWR LED area from the Ten Years After Mezmerize special edition board prototype. The production one as available on the DIYA shop is blue with gold pads and thick copper.
Attached Images
File Type: jpg TYAMEZ_PWR_LED_PADS.jpg (233.8 KB, 215 views)
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Old 28th December 2018, 07:09 AM   #288
gwolfman is offline gwolfman
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Thanks @Salas for pointing that out. The actual procuction board doesn't have such designation (and even looking now I can't find where VDD is specified).

Any thoughts on these alternative LEDs?
Quote:
Originally Posted by gwolfman View Post
Salas. I contacted the manufacturer and they recommended these:
WP144IDT

Will they work as well? It appears to just be a different shape (from all I can tell).
Lastly. I have both quad matched 2SK170B and LSK170B, any thoughts on which would sound better? Linear Systems claims lower noise than the Toshiba's, but I'm not sure about SQ. Either way, I'll be putting 6 unmatched LSKs in the power section; I'm assuming mixing (power and audio sections) is permissible, as long as each section matches.
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Old 28th December 2018, 08:40 AM   #289
gwolfman is offline gwolfman
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Sorry, the edit button doesn't seem to work from my phone (was going to tag this on at the end of my last post), but what options are there for adding a second output? Do I just run it in parallel with the first? Will that affect the SQ or output impedance (both if I'm only utilizing one connected device or even using both simultaneously)? Or do I need to use a selector or something else to do it properly?
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Old 28th December 2018, 10:48 AM   #290
Salas is offline Salas  Greece
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Mezmerize B1 Buffer Preamp
1. Does your board have "Ten Years After" printed on it but it does not have the PWR LED designation? Maybe its one you bought before the TYA issue? In any case it should have a 2.2K resistor and one LED at the same places.

2. The WP144IDT manufacturer recommended replacement looks good. It has identical parameters to WP2273ID. The difference is only cosmetic i.e. its top corners are not curved as in the WP2273ID.

3. I am not sure if there can be any detectable differences between the Toshiba and the Linear Systems, especially in unity gain as used here. Prefer the quad in which there are units to be found closer together per pair for IDSS in my opinion.
Those quads % spec could have been originally different also. For example in a power amplifier's input pair there could be 1mA tolerance target to declare a match but in DCB1's direct coupled CCSed source follower circuitry 0.1mA-0.2mA spec for excellent DC offset. You should always verify tolerances when buying matched semiconductors anyway.

4. You should "buffer" a tapped off secondary output with a 100 Ohm high quality resistor in series with each one of its RCA chassis connector's center contact.
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