Yamaha PM-1000 power supply question

[mattvon]

Hi all, relative newbie here.  I've just undertaken a Yamaha PM-1000 channel strip racking project and am now considering my power supply options.  I've seen a lot of guys use a Power One 48v supply, but the model I've seen specified most often has been discontinued (I'm guessing 'cause it's non-ROHS)...

So I started digging around online and found this:
http://www.mpja.com/48-Volt-Power-Supply-500mA-25W-Switching-Hengfu/productinfo/18445%20PS/

I really like the price but wonder if I'm missing something.  I was planning on using the "string-of-diodes" approach to drop the voltage to 44v for the module, and running the phantom off the power supply as is.

Does anyone have any thoughts on this?  Am I far off base or would this power supply work for me?  I've read a number of threads and think the 500ma would be sufficient for powering two channel strips, but I'm completely open to advice from those who've had experience...

Thanks very much in advance!

Matt

 

[analogguru]

When you look at the picture you will see an orange trimmer beside the green LED.  With this trimmmer you should be able to adjust the output voltage.  But I wouldn´t use a SMPS for audio applications.  At least I would add some additional LC-filtering.

 

[Brian Roth]

Mouser shows stock:

http://www.mouser.com/ProductDetail/International-Power/IHB48-05/?qs=%2fha2pyFaduiq4vg1iEXiYs0eTlhKJQHMkAMQnswFwy8%3d


Bri

 

[mattvon]

Excellent!  My thanks to both of you...

 

[squib]

Just racked a pair of PM1000. Used s 48V SMPSU, which gave me phantom and dropped to 44V using a jlm trex. Had no hash in the audio output.

 

[mattvon]

Thanks for the reply...could you share which 48v SMPS you used?  Was it the one from JLM here:  http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=80 ?

If so, I'd be interested in how you connected it to the Trex kit...or, for that matter, if I'm better off using the chain of diodes on the 44V line.

 

[Brian Roth]

Interesting that JLM has this to say about that switcher:

"The 48v output is fairly smooth and noise free as is but is super smooth when run into a simple RC filter on the output made with a 10R and 470uF 50v cap like all of our Baby Animal kits have on there PCB's."

That implies to me the output has some "hash" floating on the DC.  But the added R in series will drop 5.2 VDC if you fully load the PSU to its rated 520 mA.  I don't recall what PM-1000 modules draw...probably nothing near to that max. rating, but there will be a bit of voltage drop across the series R.

I am not a huge fan of SMPS units.

Advantages of the JLM unit over the open frame linear?  Higher efficiency, and UL safety listing out of the package.  No need to mount the supply in a metal enclosure with added AC mains cord and fuse like you need to do with the open frame linear.

Bri

 

[okgb]

the five fish guy , who got a springboard start from here [ ran a grp buy then turned it into a business,
I don't think he bothers with white market ads here, although the support would be nice  ]
has some options for exactly the Yamaha

http://www.fivefishstudios.com/diy-kits/psu-4448mk2-kit

 

[Andy Peters]

Interesting that JLM has this to say about that switcher:

"The 48v output is fairly smooth and noise free as is but is super smooth when run into a simple RC filter on the output made with a 10R and 470uF 50v cap like all of our Baby Animal kits have on there PCB's."

That implies to me the output has some "hash" floating on the DC.  But the added R in series will drop 5.2 VDC if you fully load the PSU to its rated 520 mA.  I don't recall what PM-1000 modules draw...probably nothing near to that max. rating, but there will be a bit of voltage drop across the series R.

I suppose that since it's an off-the-shelf model probably designed for less critical use, it is what it is.

I am not a huge fan of SMPS units.

That's because you have to choose a unit which isn't designed for efficiency (or cost) alone.  One can design an SMPS whose noise performance is "good enough" for audio.

As part of a recent design I used a TI TPS61081 to generate 48 V for phantom power for two mics from nominal 5 V input. I can't see the ripple on my oscilloscope.

-a

 

[Brian Roth]

I should have qualified my statement.  I am not a big fan of SMPSU's in line-lump/wall-wart packages, nor the "prefab" PCBs often found inside a lot of gear.  The reliability is dicey, and when (not IF...lol) something blows there is little hope of doing any repairs, especially if something has toasted.  No service docs are ever available, so you hope to find something to swap out for the entire blown module.

Bri

 

[mattvon]

Thanks to everyone for the replies!  I looked at the FiveFish power supply, but it's been unavailable for a long time.  Too bad, as I have a pair of FiveFish SC-1 preamps in my Lunchbox and I like them a lot.

I'm leaning towards the power supply from Mouser.  I know I'll have to mount the supply in my enclosure and add a fused IEC inlet, etc...but I guess I'm more comfortable connecting that to the module than the "line lump" solution from JLM.

I'm sure I'll have "double-check" questions regarding the wiring of the open frame supply...I'm grateful for the help and advice I've received so far.

 

[mingus2112]

What did you end up going with?  I've been looking at this one from JLM:
http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=122

Not much in the specs department, but i'd have to assume it's as good or better than the line lump supplies he lists.  Anyone have experience with this specific supply?

-James

 

[Matt C]

seems like it would be super easy to build your own version of the Five Fish PSU on veroboard or something like that.  That's what I'm planning on doing for mine.

one thing that threw me off about that Five Fish schematic though, it claims to be using two LM317T chips as voltage regulators, but as far as I can tell those have a maximum output voltage of 37 VDC.  I figured I'd have to use the LM317AHVT, which goes as high as 57 VDC on the output.  Or am I missing something here?

 

[Harpo]

one thing that threw me off about that Five Fish schematic though, it claims to be using two LM317T chips as voltage regulators, but as far as I can tell those have a maximum output voltage of 37 VDC.

Abs.max. 40V differential (60V for the HV type) between vregs input and output.

 

[Matt C]

one thing that threw me off about that Five Fish schematic though, it claims to be using two LM317T chips as voltage regulators, but as far as I can tell those have a maximum output voltage of 37 VDC.

Abs.max. 40V differential (60V for the HV type) between vregs input and output.

I don't know, everything I've seen says output voltage adjustable from 1.2 V to 37 V.  But you say it can go higher?

 

[mingus2112]

http://www.mouser.com/ds/2/260/nes-15-spec-49212.pdf

This doesn't say what frequency(s) it switches at, but says that the ripple and noise (200mV for the 48v version) is tested at 20MHz.  Any idea how suitable this power supply would be for mounting inside a pm1000 chassis?  How far away from the boards (i.e. how deep should the chassis be) for something like this?  Is the distance less important than with a linear supply / big honkin transformer?  I ask because the most affordable chassis I could find (about $50 shipped for 2U) is 12" deep.  If I go deeper, i'm looking at $78 plus shipping!

-J