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Philips CD850 MK1 skipping on some CDs

May 13, 2018, 12:06 pm
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Hi,

I have a Philips CD850 MK1 that skips and skates on CDs that play fine in other players. Brand or very clean CDs play OK. I changed some "out of value/high esr" axial caps on the main board and that improved the situation slightly but the problem persists, slightly dirty CDs that play fine in all other players skip in the CD850.

Can anyone suggest where else I could look? PSU voltages are all ok.

Thanks!
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Ebay: 500W +/-70V PSU Audio Amp High-power

May 13, 2018, 2:51 pm
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Hi,
I bought this power supply form eBay.
I blow it up with a short on the output.
I replaced 2 FET transistors blown,
and the back 0.1ohm R, but is not enough.
Looks like the no-name black module between
the caps and transistors is busted too.

404 Not Found

Is molded in epoxy and smashing it I could
not figure the schematics.

Would be great appreciated s schematic for such
Chinese power supply.

Thank you
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"Samoyed" digital audio platform

May 13, 2018, 3:21 pm
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Hi all,

I figured I would post this project here as I'd like the community to be aware of it and see if there is any interest or feedback. It's a multichannel digital audio interface that is fairly modular in that DAC, ADC, source, and clock boards can be interchanged to suit application/listening preferences. (The challenge is to enable this flexibility with as little compromise as possible in audio quality.) It builds on a lot of the ideas that I've learned about from this forum--Jung regulators, asynchronous FIFOs, galvanic isolation, low phase noise clocking, etc.

I have a working version (used as streaming server and FIR digital crossover) now and I'm trying to decide where to go with it to make it more usable by others. This is a long term project, so don't expect quick results. But I plan to keep up the effort.

I've open sourced the project via GPL and Solderpad licenses. The source code, PCB designs and accompanying documentation can be seen here:
GitHub - pricem/da_platform: DIY digital audio platform

Thanks
Michael
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FS : XRK Class A Headphones Amp ( Desktop built )

May 13, 2018, 3:28 pm
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I'm selling my XRK PCA (desktop version) amp, Custom handmade all wood enclosure with Cornell Dubilier 940C input caps and 1000uf Panasonic FR Caps.
I made this for myself, great sounding beautiful amp, but i have to let this go at the moment.

asking price is 250$, PP only.

Click the image to open in full size.

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Memphis Mojo 16-MC1.4000

May 13, 2018, 4:02 pm
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Hello i'm from Tahiti and i want to buy the alimentation module for my amp anyone can help me please
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2x250watts amp please have a look

May 14, 2018, 8:38 am
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Amps different temperature - Parasound 2200

May 14, 2018, 8:55 am
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Hi folks

I got 2 Parasound 2200 mkII - each running bridged mono.

One (according to my cheap laser) has about 48°c/118°F and the other 55-60 (130-140°F) at the cooler.
Which one is normal? And how to fix it?

Just bias poti oxidated, spray turn measure enjoy? :) I hope...

cheers
Josh
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New SB Satori coax

May 14, 2018, 9:32 am
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Full Range Recommendation for OB, High Efficiency

May 14, 2018, 9:41 am
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Hi, I hate to ask this, because I'm sure others have before me.. But I don't have a ton of time for research right now.. (Just bought a new house that I'm rehabbing, and I need speakers for it).

I have a pair of Emminence 15" woofers. I want to build an OB speaker system for them. I will be bi-amping w/ active xover. My amps are both only about 5 watts.
The active xover gives me a lot of flexibility.

I was going to go for alpair 7 or 10's, but just looked at their efficiency, and they aren't great there. And, then I started going down the rabbit hole of looking at everything available and second guessing every thought I have... Then I notice over 2 hours have passed and I should be ripping out old kitchen cabinets.

So, maybe I'll see if anyone here is kind enough to answer my question so I don't need to spend hours researching :).

I've always used fotex full range drivers in the past.. (I've built a few horn speakrs and one FAST style pair). So, I do like fostex, but would try anything. I would like to spend under $200 per driver.

That might be all the info you need.

Thanks for any advice.
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26 or 71A

May 14, 2018, 10:15 am
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Has anyone ever seen a SE Triode amp (or schematic) that uses a 26 as the output tube and a 71A as the driver? Or vice-versa?
Thanks
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Would 3W makes an enough tweeter resistor?

May 14, 2018, 10:54 am
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Found this:

ERX-3SJ3R9 Panasonic Electronic Components | Resistors | DigiKey

A metal film under $1 so no point using wire wound any more?

I am counting on the tweeter to burst into flames before this resistor does, of course.

I know it depends on the crossover point, the total wattage, and the power distribution between the tweeter and the resistor of course (no worry if the resistor is 0.1 ohm). So let's say 1.7k, 40W noise rated power, 4 ohm tweeter (-6dB or halving it is the goal hence 3.9 ohm resistor).

Thanks in advance!
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And now the fun part - internal wiring selection

May 14, 2018, 11:52 am
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So, I've got my modules and power supply. (2) TI TPA3255EVM and a Meanwell 600W power supply.

I'm kinda fumbling around trying to figure out which wire type and diameter to use. I've seen a few different opinions in a few different threads.

I'm guessing that wiring for power and signal doesn't have to be as exotic as most audiophiles would have us believe. Since I'm saying things like that, I clearly wouldn't know the difference, anyway. But I'd like to do as good a job as I can, within a reasonable pricing structure.

Advice on wiring and terminal connections?
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Sunfire HRS-8 Schematic

May 14, 2018, 11:53 am
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Recently, I fixed a Sunfire HRS-8 subwoofer from a friend of mine. I drew the circuit of the audio preamplifier board. To help others with the same problem I am posting here.

Attached Files
File Type: pdf SunfireHRS8_pre.pdf (64.1 KB)
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Electro Harmonix 2A3 above 300V?

May 14, 2018, 12:39 pm
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I've noticed that the EH 2A3 specifications indicate a maximum plate voltage of 450v, well above the 300v limit for conventional 2A3s. If that's accurate, it should allow increased power output from a class AB1 push-pull pair, above the 15W or so possible with conventional ones. If the tubes were biased at 40mA and 360v, for instance, it seems like 20W might be possible, still keeping within the 15W plate dissipation (at quiescent, at least). I'm curious enough to buy a pair and try it.

But first, I'm wondering if anyone out there has experience with the EH 2A3 above 300v?

Thanks,
Scott
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Preamplifier

May 14, 2018, 1:36 pm
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Has anyone here ever built a pre-amplifier out of 26s?
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replacement transistor for Pioneer SA-510

May 14, 2018, 1:46 pm
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Hello,
My Pioneer SA-510 has a bad power transistor on one channel. It's a NEC B773A (PNP), out of production and difficult to find.

It's the first time I try to fix something like this, and I was wondering:
  • If I substitute for another transistor, should I replace the complementary NPN (D883A) as well?
  • Should I change the other channel's transistors as well?
  • Can anyone recommend a good substitute?
    (I have looked here: Transistor B773A datasheet - NEC extended view but all proposed substitutes seem difficult to find)
Thanks!!
Bram
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01A pre-amp, multiple chassis grounding

May 14, 2018, 2:36 pm
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I'm building Ale Moglia's 01a pre-amp, using his awesome gyrator boards and
Rod Coleman's fantastic filament regulators. I am using three separate
chassis, one for the pre-amp(signal), one for the HT supply and one for the
LT(filament) supply.

I have a few questions, regarding general grounding
(signal and physical earth) best practices and screening the umbilicals
feeding the signal chassis.

I'm using 5 pin military circular connectors for the power umbilicals, and
have drawn a quick diagram to help me work it all out and hopefully ensure
I get it done correctly.

The umbilical cables are each using 2 pairs of 16awg stranded silver plated
copper with teflon insulation. Each +,0v pair is twisted, the 4 conductors
then get a couple wraps of teflon tape and are then put into a braided
copper tube.

FWIW, in the LT chassis diagram the physical earth connection doesn't imply
that I'm intending to connect the Coleman raw dc boards to physical earth.


1 - Do I need to connect the screen(braided tubing) from PE in the LT chassis
to a PE in the signal chassis?
A - same for HT chassis?

2 - If yes to question 1, should I have only 1 PE in the signal chassis that
they both connect to?


My second set of grounding(earthing) related questions are in regards to the
signal chassis. The line down the middle of the pre-amp(signal) chassis
represents a ground buss bar in that chassis. My intention is to connect the
grounds from the Coleman regulators, the Gyrator boards, and the input/output
grounds to the same spot on that ground buss.

1 - Is that correct?

2 - If so, does the ground buss bar need to tie into a PE?
A - a separate PE from the LT/HT incoming PE point(s)?


This is my first multi-chassis build, and I want to ensure I don't screw it up
anymore than is absolutely necessary....:D

Cheers,
Gable

Attached Images
File Type: jpg 01A Pre Wiring.jpg (39.4 KB)
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All-In-One Class D project- Need a tube preamp suggestion

May 14, 2018, 2:57 pm
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I had been planing to make a cheap Devialet type design for years.

After few Class D chips I decided I like the TA2022 chip the best. So, I am purchasing this board. Yuan-Jing TA2022 2 x 180W Audio Power Amplifier Board

I need a tube preamp suggestion for this amp. I would appreciate any suggestion. I'd prefer a remote control but it is not a must.

I will be using RPi with Allo Boss DAC.

I want to put everything (amp+pre+Rpi/DAC) in one box.

Another question is regarding transformer:

I plan to power every component separately with a toroidal transformer if possible with dedicated IEC inlets. Any reason why I shouldn't/no need if I can find cheap transformers?

Thanks!
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FS: M2x daughter cards, type "TUCSON"

May 14, 2018, 3:13 pm
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I ordered a whole bunch of extra Tucson PCBs and wish to sell them off.

These are removable "daughter cards" that hold an IC opamp input stage for the diyAudio First Watt amplifier named M2x.

You can stuff and solder Tucson using a thru-hole opamp. And/or you can stuff and solder Tucson using a surface mount SOIC-8 opamp. Some of the latest and greatest opamps, introduced after 2010, are only available in surface mount packages. Don't yell at me, yell at Analog Devices and Linear Technology and Burr Brown and Texas Instruments.

I imagine that people may want extra Tucson boards for a couple of reasons. (i) because they want to build 2 Tucson boards using thru-hole opamps, and another 2 Tucson boards using SMD opamps; (ii) because they made a terrible error when stuffing and soldering their Tucson boards, and now they need a do-over.

I ordered these extra boards from one of those super-cheap PCB fabs in China that achieves rock bottom prices by having extremely slow shipping. So I won't get my Tucson PCBs until ~ June 15th and won't be able to ship before then.

Price is $1.50 per board (maximum of 6 Tucson boards per customer) plus $5 per order if shipping inside USA, or plus $15 per order if shipping outside USA. Please read that sentence two or three times before posting a question. Sorry that the shipping rates are so high; I have no control of this. Payment will be via PayPal.

Add your diyAudio userId to the list below, if you want to buy some Tucson boards. First come first served unless the total quantity desired is gigantic. In that case I'll give preference to people who bought an M2x from me. People who want to buy Tucson boards but don't yet own an M2x -- you may get shoved to the end of the line. Kind of like "Legacy" admissions at Ivy League colleges.

Code:
DIYA_userid, #_PCBs_wanted
==========================
Mark Johnson, 2
(add your name here), nnn
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Potentially Wanted: 845, 211, 805 or GM-70 Amplifier (Mainly Trade)

May 14, 2018, 3:50 pm
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Someone on a different site suggested to try diyaudio, so here I am.

It is a long shot but, per the title, I am interested in an amplifier (stereo, monoblocks) based on 845, 211, 805 or GM-70 power tubes if I can find the right deal.

Cash is limited, but I do have trade options including Dynaco MKIII monoblocks (working, sounds nice but could use a checkup/update in a couple of places), Radio Craftsman RC-2 monoblocks (again working and sounds nice, but could use a checkup), Linear Audio MicroZOTL 2.0 (with upgraded power supply), McIntosh C35 preamp (with Harmony 659 remote), a pair of Atma-Sphere Z-Music Transformers, Eastern Electric Minimax DAC (w/ Burson opamps, but one channel needs work), various vacuum tubes, SACD's and even things like fine wine/port (properly stored).

I am in Chadds Ford (PA). A reasonably local transaction would be nice, as anything else adds another layer of cost and complexity (but shipping is not entirely out of the question).

I am not a stickler for physical condition (everything has a price), but I would like an amp that is functional. Can be branded or custom built. For the right value, I could even consider one that needs a little work (especially if a schematic is available).

Lots of variables to play with here, so feel free to drop me a PM or send an email to baileyler@comcast.net.
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