[Matt]

Hello, all.

I am not interested in paying $149 for a Creek OBH-2 power supply, but I would like that same sonics upgrade. I would like to either buy a Stancor-for-the-Art-DI/O style pre-made supply somewhere, or make one.

I see RatShack has a switchable 18/24V PS, but it's AC-to-AC...damn.

It has to take 120V AC U.S. wall power and output 24V DC @ anything at or above 225 mA, preferably 1 A. The OBH-2 is 12 watt, so I assume it ought to be that as well. Also, it should be regulated, just like the OBH-2 PS.

Any clues?

- Matt

 

[Dreamslacker]

Get the Elpac 24v power supply that most people use for the META42 amps. It's linear regulated and at least as good as the OBH2. Probably even better. Just terminate it with the 3mm DC plug and you're good to go.

 

[tangent]

I haven't measured them, but from having looked at the insides of both the Elpac WM-080 and the Creek OBH-2, I would say the OBH-2 is likely to perform better, especially at higher loads. Both are generic linear regulator designs. Some distinctions between the two:

- The Creek is bigger all around. Bigger transformer, bigger case, bigger main filter cap, bigger heat sink on the regulator.... This explains part of the cost difference, and also why the Creek is capable of putting out 500mA vs. the Elpac's 330mA.

- The Elpac is a more efficient design. It uses an LDO regulator and a Schottky diode bridge. This is why it runs so cool and why it can be in such a small case. The Creek is more of a brute force design. It uses an LM317 and ceramic-bypassed silicon diodes.

- The Creek has better filtering all around. This is why I say that it probably performs better at higher output currents.

- The Creek has an LED. The Elpac does not. Woo.


Could you do better than the Elpac by DIYing? Only maybe. To make an external power supply for less than the $30 the distributors want for an Elpac, you'd really have to be careful what parts you used, and when you were done you probably wouldn't have any better performance. You could do better if you were putting the power supply inside the case with another project, since you could trade the cost of the case and connectors for better performing parts. Or, you could get a cheap unregulated power supply and follow it with a linear regulation box. But, all told, the Elpac is mighty convenient.

Could you do better than the Creek OBH-2 by DIYing? Yeah, probably. $149 in parts would go a long way at DigiKey.

 

[Chipko]

I've just finished a "universal powersupply" from Zero-distortion.com parts costs was around USD100 but that's for a three voltage Toroid +/-12 and 5V at 55VA which is a bit of an overkill. I overspent on the rest of the parts to make sure I will be able to use the power of the toroid if I need it for something else in the future.

It was pretty easy to build as I managed to lay it out on a single side of a project board. Will post pictures as soon as I get a hold of a camera.

Parts are expensive in Sweden so you should be able to build something similar for a lot less money, maybe even half if you get a cheaper transformer.

 

[Matt]

...the higher mA or A rating mean that for powerful musical peaks, the power supply can, well, supply that extra power, therefore leading to better dynamics, etc.? Furthermore, the regulation does what in audio terms?

- Matt

 

[tangent]

Quote:

..the higher mA or A rating mean that for powerful musical peaks, the power supply can, well, supply that extra power, therefore leading to better dynamics, etc.?

Well, I guess, to a small extent. That's really not the point of a high-amperage power supply, though.

Instantaneous current for musical peaks is supposed to be handled by the power capacitors in the amp. The power supply is there to charge those caps back up when the power peak goes away.

The amperage rating for a power supply gives you an idea of how it will behave at different loads. If you have two power supplies with the same output voltage and the same specs at full load, but one is capable of 500mA and the other 250mA, the 500mA one would be about half as noisy with a 250mA load as the 250mA one.

If you're trying to draw nearly 250mA from a 250mA power supply, then you might see big improvements from going with a 500mA supply. But if you're only drawing 25mA, going with a 500mA supply won't buy you much. This has to do with how fast the power caps get charged back up. If they don't get charged back up as quick as the amp demands power, you get ripple on the power rails, which gets through the amp in more or less audible quantities. This results in a blurring of the sound since the ripple is in sympathy with the music. (This is as opposed to constant ripple like power supply noise which manifests as an audibly separate hum.) Pushing a power supply to near its limits is not a major sin -- look at how many amps there are out there running on alkaline batteries! But, it is a worthwhile thing to improve on if you have the money to spend.

Quote:

the regulation does what in audio terms?

See this:

http://tangentsoft.net/audio/opamp-ps.html

Especially the bit on unregulated power supplies.

 

[divie23]

one question - having just built a regulated lm317 PS, how do i go about measuring its output current? This is prob a real dumb question but i couldnt figure where to place my meter probes to do this.

 

[Chipko]

Maximum output current is hard to measure since you will essentially need to increase the load until it supercedes the temperature specs or until the Voltage starts to fall. Both will happen roughly at the same time if the LM317 is the bottleneck. You will also risk damaging the powersupply doing this.

If you just want to know how much current is used at a certain time you will need to unplug one lead between the PSU and load and put an amp meter in between.

As long as the regulator isn't hot to touch and the output voltage is stable you're safe.

 

[tangent]

Chances are excellent that the transformer is the bottleneck. What does it say for its output current ratings?

 

[Matt]

...hello again.

Well, the Elpac WM-080 arrived today. It's a beaut, though I am not able to test it (my gear is at mother's house). You mentioned earlier in this post that power supply noise manifests itself as a separate hum. I am curious to know this:

The Creek OBH-8 hums for me, and the record player is grounded to the Creek's screw-in ground knob. Elpac has that third, "separate" ground post thingie (don't know what it's called), where the stock Creek supply only had the two prongs.

It seems that when I touch the chassis of the Creek, the mint tin amp I am temporarily using or a certain screw on the turntable, a certain somewhat prominent harmonic of the hum goes away.

Does this third post mean I am going to get better grounding and therefore less hum? Furthermore, is this PS (in theory, if not reality) going to reduce hum in any other way(s) with the Creek phono preamp?

Thanks so much.

Regards,
Matt

 

[Ebonyks]

Matt, i had the exact same hum problem with my OBH-8 and managed to figure out the problem. How close do you live to a radiostation? the creek stock (obh-1) PSU is basically an antenna for RF signals. The elpac (i'm assuming it's better designed than the creek), should fix the problem.

 

[Matt]

...that there are some low-profile stations (i.e. no MegaCorp.-looking buildings) around here broadcasting, but I'm at least a few miles away. I dunno if that makes a difference or what. I am in a rather populous area, so I wouldn't doubt that there's tons of interference.

I will be trying the Elpac PS out tommorrow night (and I may not have to do any soldering, as the stock connector may very well fit into the Creek, I don't know...it sure looks like it) and I will certainly let you know what happens. No expectations on this end, so we'll see.


Best regards,
Matt

 

[Matt]

OK, fellas, I've brought the unit home and have some rough, preliminary results:

I am using my POS Sony VITE's for this review, which sound fabulous and way, way more Ety-like than they ought to, except for the fact that they have an uneven (albeit euphonic) response curve and have the extreme high end rolled off. Are they the last word in audiophilia? Hell no. Are they easily one of the best NOS "cheap can" values out there? Absolutely.
For amplification, I'm using a JMT Mint tin amp, so take this as only a rough, general guide.

Here is what I got (note that the "bad" points from the stock supply are only in relation to the Elpac...they're not really that bad without comparison):

0. The "Shhhhhhhh" is still there...this could be the Mint tin amp, though. HOWEVER, the "HMMMMMMMMMMMM" is just about completely gone and the occasional "fwweeeeeggrrrhhhssshhheeeeezzzxxxzzeeerrhhxx" squiggly stuff is completely gone. Go Elpac!

1. Joe Venuti & Marian McPartland - "Dinah" (gorgeous, closely-mic'ed violin/piano duo)

Stock: piano and violin are extremely close to the ear, both vying for attention. Strident and (slightly) unpleasantly bloomy.

Elpac: The instruments "step back" from the mic a pace while at the same time gaining extra detail; for instance, we hear the violinists use of touched harmonics more clearly and it takes on a more natural, fairy-floss, flutey quality. The piano sparkles where before it fairly yelled. Naturally, one could also infer from this that dynamic contrast and gradation improves and that it does.

2. The Brothers Johnson - "Stomp!" ("We're gonna stomp...all night...in the neighborhood...don't it feel alright?") Change from stock to Elpac reveals the trailing ends of the bongo (reverb) trailing off significantly longer. It's more apparent that there are two distinct background singers, two separate bodies with separately distinctive voices. Not a huge overall tonal change, but those "little details" are far more present.

3. Ray Charles - "The Same Things that Can Make You Laugh (Can Make You Cry)": The Elpac gives a less wooly, pounding bass guitar, making it how it's supposed to sound: like low musical notes. In other words, musical bass, not just tactile, with intricate, pleasing string ripple and easy solidity of tone. Thick and solid bass, very much alive and in the correct proportion. Again, the Elpac reveals the distinctness of the separate bodies of the singers, rather than one "choral mass," while generally enhancing musicality with greater realism.

Would I say that this $28 purchase was worth the upgrade? Take a wild guess...

I would say this is certainly on the magnitude of a $149 upgrade, except that it was only $28.

As soon as I get my *^%&$ KGSS, I'll do this again, as if you weren't already entirely convinced.


Regards,
Matt

 

[Ebonyks]

Thanks for being the guniea pig on the elpac PSU on the creek, i'll probably place and order shortly. Just one question though, does the barrel fit the creek, or does it require soldering?

 

[tangent]

Quote:

Elpac has that third, "separate" ground post thingie (don't know what it's called), where the stock Creek supply only had the two prongs.

Modern house wiring has 3 connections, here in the US at any rate: hot, neutral and ground. Your main electricity is from hot to neutral. Neutral and ground connect back to an earth ground at the point where the electricity comes into the house. Power is delivered between hot and neutral. Ground is for protective purposes only. The only place it should connect to in any powered device is the case.

In the case of the Elpac, it isn't clear to me why they use a 3-prong plug. It isn't helpful given that the output from the power supply is only 2 connections.

Don't try to hook anything to the ground prong on the power supply! As I said, only chassis are supposed to be connected to that prong.

Conversely, the ground lug on the OBH-8 you have goes back to neutral, which should be plain: there is no ground connection through the power supply to connect back to! This is also okay, because the purpose for that lug is to be a ground for the ground wire from the cartridge. You wouldn't want to connect that to true ground, but to neutral.

The reason the OBH-8 hums and requires that connection is because it's a very high-gain device. Cartridge outputs are far lower than line level -- that's one of the reasons you need a phono preamp. Because of this high gain, you can pick up any low level hum or interference much more readily than with, say, a headphone amp.

Quote:

is this PS (in theory, if not reality) going to reduce hum in any other way(s) with the Creek phono preamp?

It won't reduce hum as a result of noise introduced in the cartridge or its wiring. It could reduce hum due to power quality issues.

Quote:

I am using my POS Sony VITE's for this review

Those are 16 ohm phones with 104 dB/mW sensitivity. The hiss is due to one or both of these causes: too much gain and need for a bit of resistance inside the amp's feedback loop. You might try having JMT reduce the gain of that amp to 2 or 3 first. If the hiss is still there, add 10 to 47 ohms in R8. Or, just get some insensitive cans!

Quote:

does the barrel fit the creek, or does it require soldering?

Creek uses 2.5/5.5mm tip-positive connectors, just like Elpac does. So, "no".