Mezmerize B1 Buffer Preamp - Page 6 - diyAudio
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Old 14th April 2014, 01:25 AM   #51
dodog is offline dodog  United States
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Quote:
Originally Posted by sibbeli View Post
is it possible to "hot rod" thé Mezmerize also?

I wonder as it seems that thé hot rodding really makes difference.

I need atleast 4 different inputs and something that is complete with build guide as a preamp, and thé mezmerize seems to be really good.

Just hoping it's possible to hot rod it too..
Quote:
Originally Posted by Salas View Post
For down to 8.2R 3W per side setting resistors and circa 200mA will hold for reliability and rectification/filtering capacity as built standard. A 50VA 15+15VAc Tx will suffice. Keep the bridge diodes bit off board for air to can move around them.
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Originally Posted by Turbon View Post
So that would be enough for hot rodding the mezmerize?
Quote:
Originally Posted by Salas View Post
Yes, more it would stress it enough. When going for more than 0.2A on the specific board it needs TO-220s botch job, leg trick, more uF in the filters, a drag. When from 60mA to 200mA there is an appreciable difference already that should satisfy.
For a medium hot-rod, is it wiser to use 10R, 5W resistors like these:

http://www.mouser.com/ProductDetail/...R%252bJEtlA%3d

(is 8.2R, 3W pushing it?) And, to be clear, you'd swap out the four 68R resistors for two (8.2 or) 10R resistors?

Do the MUR120 diodes need to be changed or left as is?

Last edited by dodog; 14th April 2014 at 01:27 AM.
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Old 14th April 2014, 01:46 AM   #52
Salas is offline Salas  Greece
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Yes you forget the 68R and use one 10R/8.2R per side. 3W will do in both cases. 10R gives less than 200mA in many builds with red LEDs. When the MOSFETs aren't Vgs matched around that current, usually the negative polarity is bit weaker and the next smaller value resistor available balances it out. i.e. different resistors to offset semis tolerances. Not that it matters much for gm difference at those levels, but its nice. MUR120 can hold until 200mA with enough reliability but have them standing bit off board.
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Old 14th April 2014, 02:58 AM   #53
dodog is offline dodog  United States
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Thanks Salas. That was my next question, the MUR120 mounting. I assume something like this:

http://server.ibfriedrich.com/wiki/i.../Rstehend3.png

Do you recommend teflon or heat shrinking the exposed lead?

I'm using red LEDs so I guess I'll stick with 10R (if I'm reading your right, or were you saying to use 8.2R).

If I were to use a case like those in the store, would it be safe to mount the MOSFETs to it for disippation or would they each require their own sinks, standing up? Since this is a "medium" hotrod compared to the others with 4x4700uF caps, I was unsure how hot things would get.

I'm doing my best to read all I can and ask all the questions I can think of. There are sooo many DCB1 threads here and elsewhere it's dizzying to keep track of. Thanks for answering the same questions again and again!
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Old 14th April 2014, 08:31 AM   #54
Salas is offline Salas  Greece
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That one upright mounting is best for dissipation. If you are not going to mess with probes there and be creating short dangers better not heat-shrink cover the leads so they can radiate to air better.

With 8.2R and red LEDs the builds go closer or bit over 200mA usually with the MOSFETs and LEDS they sell these days.

Yes case mounting will suffice.
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Old 3rd June 2014, 07:40 PM   #55
dodog is offline dodog  United States
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The last thing on my build list is a 6-position switch. I have some knobs I'd like to use that are 6mm but it looks like most switches are with a 0.25" (6.35mm) shaft. Could someone verify that this part from Mouser (688-SRRN161100) is an acceptable 2-pole, 6-position selector switch?

SRRN161100 ALPS | Mouser

If I'm reading the data sheet correctly, the shaft is slightly less than 6mm so there should be some wiggle room. Also, I'm not sure what voltage rating these would need to be.

If I've made a bad choice, could someone help me find an acceptable solution (preferably from Mouser)? Many, many thanks in advance.
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Old 3rd June 2014, 08:44 PM   #56
Salas is offline Salas  Greece
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Its a typical switch alright. Its role here is to just close path to ground for the selected input relay coil each time to engage. One side of the switch is to be utilized only i.e. 6 positions and their single exit. Voltage level is very low (5V or 12V) at a few mA that one relay coil draws. The other side is left idle or can be used for tricks like for switching on LEDS signifying active input position.
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Old 17th June 2014, 12:42 AM   #57
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any idea when more pcb's might be in stock?
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Old 12th August 2014, 10:57 AM   #58
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Can you please explain the main differences between Mezmarize and the Pass B1?

I am trying to decide between the two. I will be looking to use the Hypnotoad CNC Phonoamp as well as a DAC.

Thanks

Lee
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Old 12th August 2014, 11:10 AM   #59
AndrewT is offline AndrewT  Scotland
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B1 is a volume control+Buffer that is AC coupled between Source and Receiver.

DCB1 is a volume control+Buffer that is DC coupled between Source and Receiver.

No difference, since somewhere one needs to block DC errors from reaching the speakers.
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Old 12th August 2014, 02:50 PM   #60
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Quote:
Originally Posted by AndrewT View Post
B1 is a volume control+Buffer that is AC coupled between Source and Receiver.

DCB1 is a volume control+Buffer that is DC coupled between Source and Receiver.

No difference, since somewhere one needs to block DC errors from reaching the speakers.
Thanks Andrew,

which one should I go for? Is the original a simpler build?

Is there a preference if it is being used between valve or SS?
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