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Mezmerize B1 Buffer Preamp
Mezmerize B1 Buffer Preamp
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Old 8th January 2019, 12:23 AM   #301
Salas is online now Salas  Greece
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Mezmerize B1 Buffer Preamp
Quote:
Originally Posted by joshua43214 View Post
Farnell is back order for international, and their site always breaks on me at check out. I gave up on them years ago.

RS for USA or Canada does not even list Alps potentiometers, and has no shipping options for the overseas options I tried.

I think maybe the best thing is to replace the pot with a header. This will give me more flexibility for board placement, and let me swap different pots in and out.
Any special considerations for the wire? I have some shielded 8 conductor 18ga twisted signal wire I used when I added speed control, tach, etc to my 3phase lathe.
I could also chop up a HDMI cable for some better wire.

Thanks
-Josh
No special wire recommendations, use whatever extension is practical to you
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Old 9th January 2019, 07:58 PM   #302
gwolfman is offline gwolfman
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Quote:
Originally Posted by gwolfman View Post
  1. Sorry, *please* forgive me. I looked over the board when I received it and it looked identical to the board shot on the DIY store. They are close, but there are subtle differences; so mine does have the power LED designation like your attached picture does (when the store picture doesn't).

Thanks a lot for the help!
So I think I've settled on the EAO 82-series switch (model# 82-5151.2123); it feels the best of the three I ordered. According to the spec sheet it also does have a series resistor in place; the manufacturer recommends 7mA of current. (See attached.) So in theory, I just short out the 2.2k resistor near the PWR LED and wire the switch up directly? Are there any tests I could/should run with a multimeter (or whatever else) beforehand so I don't accidentally burn it up?

Thanks again. I've got all my parts ordered minus the chassis. I'm getting excited to put this together!

Btw, are there any videos of someone putting one of these together? I've never made a video before, but maybe it'd be helpful for others if I did.
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File Type: jpg EAO-82series-LED.jpg (37.8 KB, 115 views)
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Old 9th January 2019, 08:22 PM   #303
Salas is online now Salas  Greece
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Mezmerize B1 Buffer Preamp
Hello, I don't think there are any construction videos. Yes, if it has independent pins for that you short out the 2.2K and you wire from the pwr led position which effectively becomes a 12VDC outlet. Unless it steals current internally from what it switches. If you have a lab supply set it at 10mA CC mode (current limit protection) and 12V DC to test it in safety on its + - illumination pins.
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Old 11th January 2019, 06:37 AM   #304
gwolfman is offline gwolfman
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@Salas Thanks for all the help so far! I'm very near to putting this all together. I might buy a lighting setup to get a good video of the build; just seeing if the wallet will allow it.

A few questions regarding the layout (#1-3, see highlighted sections in 1st image) & additional questions (#4-6)...
DSC_0512_annotated.jpg
  1. Do I just jumper/short this section (like the jumper between the MUR120s)?
  2. What's this for? For verifying the voltages? If so, does it go top to bottom: V-, G, V+?
  3. This is the vertically mounted resistor, correct?
  4. Is there any benefit to upgrading the 100uF caps with something like UKZ1E101MPM (I believe the original BOM said 25V caps was sufficient) or UKZ1H101MHM?
  5. The two heat sinks are for the 9240s, correct? What's the method to attach the HS to the chassis? (Sorry, I'm new to all this.)
  6. Alternatively, in someone else's build, looks like they mounted the 9240s on the chassis floor (see 2nd attachment below). Additionally, it looks like they even used wires as an extension. Will this degrade the audio quality?
2rruwqs.jpg

Thanks again as always.
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Old 11th January 2019, 08:00 AM   #305
dewdrop is offline dewdrop  Singapore
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I like your layout! Wished I had done the same.
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Old 11th January 2019, 10:02 AM   #306
Salas is online now Salas  Greece
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Mezmerize B1 Buffer Preamp
@gwolfman

1. Its an already connected section in dual layer Mezmerize blue boards (not in legacy single layer black boards) but its reinforcement with wire jumper is also welcome. That portion is the ground lane's thinnest travel section.

2. Yes, its mainly for verifying voltages. Or to tap off regulated DC for low consumption utility circuits, but not recommended to do that if not having the instruments to check that no interference has been introduced on the rails.
Also, in older days before I had general use shunt PSU projects out there (SSLV1.1_BiB/SSLV1.3_UltraBiB) some people used the Mez board for its shunt PSU section alone to power other projects. They liked this shunt PSU's character in many apps, not for what it brings to the Mez only. Few left hand side signal select and JFET buffer major board areas simply got hacked off and ended up in the bin back then...

3. Correct

4. Subjective area. If keen for detail you may replace types there, then listen to your system's synergy in personal taste and decide. Yes, 25V is enough for the 100uF caps. If you have good rework skills and tools it can be a very easy and clean swapping job. Or you can put small female pins while using cut to short legs various capacitors for listening back and forth with until you decide. Mind you that's a sure recipe for developing audiophilia nevroza

5. Absolutely essential to insulate the MOSFETS for sinking in common metal between them. Else kaboom! You need TO-247 sized insulator pads as listed in the 2018 BOM or alike. Not insulated screws and nuts though because such type MOSFET cases already offer an insulated mounting eye area. In the end you better test your assembly work for there is no continuity beep with a DMM's special test mode for shorts, when touching the probes between a conductive chassis point and each MOSFET's middle pin successively (do that before powering on).

6. A substantial chassis is also good for sinking this project, (run as BOM standard), instead of dedicated sinks. If must have MOSFET pin extensions, not obvious degradation occurs before the length of extension wires passes a critical point and PSU oscillation appears. Wire self inductance is not good news there, although this design has some degree of tolerance in matters practical, its not meant to be abused either. If you have no oscilloscope and experience in its use to verify the rails are clean from oscillation, better don't modify with extension wires when avoidable.
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Old 13th January 2019, 08:17 PM   #307
md_Stryker is offline md_Stryker  United States
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Quote:
Originally Posted by joshua43214 View Post
...
Also,
The Alps pots are pretty much unobtainium in the US it seems from reputable dealers.
Plenty of them on Ebay, made in Japan - ships from China...
Mouser sells 100K ones, they list exactly 1 10K pot, but it is really a 100K according to the spec sheet.
I ordered what may be a fake from a US seller. Will let every one know what it looks like it gets here.
I have found the RK27112A00A6 20 kΩ Log at Newark/element13 for $15.33.
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Old 13th January 2019, 09:06 PM   #308
joshua43214 is offline joshua43214
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Quote:
Originally Posted by md_Stryker View Post
I have found the RK27112A00A6 20 kΩ Log at Newark/element13 for $15.33.
Thanks.

The Ebay item I got actually seemed to be authentic. If it is a forgery, it is a good one - free shipping too
ORIGINAL & Brand New ALPS RK27 27 Type Dual 10K 10KA X 2 Potentiometer US Seller | eBay


I actually prefer moving the pot off the board so I can swap pots in and out, or try something like a lightspeed. It also gives me flexibility in terms of board placement.
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Old 16th January 2019, 12:27 PM   #309
reddish75 is offline reddish75  United Kingdom
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Are there any layout/circuit changes between the 10th year edition and the previous one sold in the store or are the differences in the BOM?


Thanks

Chris
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Old 16th January 2019, 03:43 PM   #310
Salas is online now Salas  Greece
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Mezmerize B1 Buffer Preamp
Changes:
1.
The mounting distances are now compatible with perforated bottom plates of the Italian chassis
line that the diyA online store carries (mechanical change)
2.
The five LEDS +/- voltage reference chains in the PSUs now work with equal current bias like
in the vintage Hypnotize hot-rod version (layout level schematic point change)
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