OBH-11SE (B) is discrete?
Apr 8, 2002 at 4:05 AM Thread Starter Post #1 of 22

vb1

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I just got my Creek and of course the first thing I do is open it up and to my suprise 'Lo and behold' there are no Op amps!
-Just heat sinked power transistors.

Hence the strange S/N ratios?


What do you make out of it?
 
Apr 8, 2002 at 5:22 AM Post #3 of 22

vb1

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How odd.

From the Creek literature and the research I've done at this web site and Headwise's I was led to believe that the OBH-11 and the SE version were the same but for an ALPS POT, Class-A design, and the larger power supply in the SE. But If the OBH-11 uses op amps, these two models couldn't be more different.


But apparently there was a design modification last year starting with the (B) series, which affected the SE only from the various posts I've read.



Now I see why Creek advises against using another power supply for the SE. Op amps are pretty good at ripple supression but I imagine the SE model could be more sensitive.

By the way, the power supply that came with this is rather large.
 
Apr 8, 2002 at 3:47 PM Post #4 of 22

Magic77

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vb1,

Some people think that the OBH-11 sounds better when using the OBH-2 regulated power supply, but I have not heard that combination.

The OBH-11SE needs the regulated supply because of the Class "A" operation. But, I'm not sure if earlier versions of the SE used op-amps instead of discrete transistors. I've had my SE for 7 months and it's the same version that you have.

The OBH-2 is quite large as you said, but if you open it up there's really not that much in there. You'll find a transformer and a small circuit board with only a few components including an LM317 voltage regulator. They probably could have fit it into a large "wall wart" enclosure.
 
Apr 8, 2002 at 7:58 PM Post #5 of 22

kwkarth

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I had both amps at one time and the standard OBH-11 sounded pretty much the same to me whether I used the OBH-1 or the OBH-2 power supply. There is an on board regulator in the OBH-11 so it is pretty forgiving of powersupply. The OBH-11SE was another story altogether. It relies heavily on external regulation of the power supply so the OBH-2 or equivalent is pretty much a requirement.

You're right about the OBH-2 itself. Not overly impressive. A very run of the mill, basic regulated supply, using very pedestrian components.

The OBH-11SE has slightly less gain, but slightly superior sound to the standard OBH-11. I ended up keeping the SE model and returning the standard model.
 
Apr 8, 2002 at 8:23 PM Post #6 of 22

Magic77

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The OBH-11SE also has an LM317 regulator on the amp's circuit board. So, your'e actually getting 2 stages of regulation, which I assume is required for the Class A circuitry.

But, overall, I think the Creek headphone amps are an excellent value for the price.
 
Apr 9, 2002 at 2:37 AM Post #7 of 22

Dusty Chalk

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I've always preferred the OBH-11SE over the OBH-11...always wondered about those people that said one was only a little better than the other...I've always said to myself, "Well, that may be true, but the OBH-11SE crosses the line into 'good', whereas I hear a small graininess to the OBH-11 that I find intolerable" -- anyone else? Everyone seems to look at me funny when I say that about it (alright, everyone == one person, I don't know any other audiophiles in real life). If so, does the power supply help eliminate the graininess?
 
Apr 9, 2002 at 2:47 AM Post #8 of 22

kwkarth

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Quote:

Originally posted by Magic77
The OBH-11SE also has an LM317 regulator on the amp's circuit board.


Really? How'd I miss that? Hmm! I could have sworn my model "A" didn't have that.
 
Apr 9, 2002 at 3:57 AM Post #9 of 22

vb1

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As far as the power supply goes, I would think that its a good outboard suppy for what it's suppose to do, albiet a bit large for a .5amp unit.

I don't know anything about external linear regulated supplies, but I do know that it is a very easy thing to test, as there is just one simple measurement with a scope.

It is tauted as 'completely' eliminating ripple , which of course is not true, but can only serve as an approximation.
 
May 21, 2002 at 8:39 AM Post #10 of 22

Moonwalker

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Quote:

The OBH-11SE also has an LM317 regulator on the amp's circuit board. So, your'e actually getting 2 stages of regulation, which I assume is required for the Class A circuitry.


Really?!

I didn't found it in my SE model version B!
Where it is???

Are B versions major modified compared to A?

Thanx
Moonwalker
 
May 21, 2002 at 3:36 PM Post #11 of 22

Alex Nikitin

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Hi,

As Chief Engineer of Creek Audio and the designer of both OBH-11 and OBH-11SE I can put some light on this topic:

Both OBH-11SE "A" and "B" versions are fully discrete. Transition from "A" to "B" version was nesessary as the main MOSFET device used in the original OBH-11SE became obsolete. We do keep a quantity of these for service needs but further production was not possible. The replacement "B" version kept the original philosophy intact but replaced the output devices with bipolars and input device with a low-noise JFET. As a result the measured performance improved considerably - I do apologise for not updating the manual accordingly in time. Actual performance data are better than that of most OP-AMP based amplifiers. If there is an interest I can put here on the forum measured figures for OBH-11SE "B" rev.

Alex

Creek Audio Limited
 
May 22, 2002 at 6:02 AM Post #12 of 22

sneared

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Nice to have the info direct from the designer.

So how does one identify an A vs. B version?

I assumed it was the serial number prefix.

I'm sure Creek is offering all us poor fellows who bought the A version an upgrade to the B?!
biggrin.gif


Love to see the performance data.

Thankx!
 
May 22, 2002 at 6:03 AM Post #13 of 22

Moonwalker

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Hello, Alex!

YES!!!!!!!!!!!

I want you to put some info how it performs!
I have that little beast and can't wait to know more from you!
It's pity the manual doesn't mention any changes.
frown.gif


You're very kind to offer that kind of sharing information.
smily_headphones1.gif


Your
Moonwalker
 
May 22, 2002 at 1:04 PM Post #14 of 22

kwkarth

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Alex,
A most cordial welcome from all of us at HeadFi!
Thank you so much for joining our little community!

We are most anxious to learn all that we can about the products we have and enjoy, and to put to rest any quandaries, questions, and perplexities we have about them.

I for one, would also love to know if Creek have any plans for an even "higher end" head amp if you could share such a thing.

Thanks and Cheers!
smily_headphones1.gif
 
May 22, 2002 at 4:16 PM Post #15 of 22

Alex Nikitin

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Hi,

Quote:

Originally posted by kwkarth
<skipped>

I for one, would also love to know if Creek have any plans for an even "higher end" head amp if you could share such a thing.

Thanks and Cheers!
smily_headphones1.gif


Thanks for warm welcome. We always looking for ways to improve our products, but at the moment there is no plans to develop a new separate headphone amplifier. There could be a cosmetics change for OBH series in a near future and possible middle-life update for OBH-11 "standard" version - it is getting a bit long in tooth as it was one of the very first headphone amps on the market when it was produced in 1995.

Here the short measurements results summary for OBH-11SE rev "A" and "B". Note: all measurements but (5) referenced to 1mW output into 100 Ohm load = 0.316 V RMS.

1) Frequency response is the same for both amps - 3 Hz to 30 Khz at -1 dB point.

2) S/N ratio non-wtd 20Hz - 20kHz B/W is 78 dB for "A" rev. and 80 dB for "B rev. S/N ratio A-wtd is 80 dB for "A" rev and 86 dB for "B" rev.

3) THD from 20 Hz to 20 kHz are <0.02% for "A" rev. and <0.004% for "B" rev.

4) Output impedance - Output 1 - 100 Ohm, Output 2 or 1+2 - 220 Ohm for "A" rev. Output 1 - 30 Ohm, Output 2 or 1+2 - 68 Ohm for "B" rev.

5) Maximum output @ 1 kHz for 1% THD (Output 1 into 100 Ohm) - 2V "A" rev, and 3V RMS for "B" rev.

We do not offer upgrades from "A" to "B" revision, as essentially it would mean replacing the unit, sorry
smily_headphones1.gif
. However, soundwise, these two are somewhat different but I wouldn't say that "A" was worse and "B" is better. Main difference is maximum output into low impedance load - "B" rev can produce more current as it has lower output impedance and more current in the output stage transistors.

Regards

Alex

Creek Audio Limited
 

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