[mecano]

Hi guys!
I keep reading about the importance of a high output imp amp to drive the Beyer dt 931.i m planning to use them with a creek amp. Does anyone know the output imp of the creek obh11?
i wiil use resistor if it helps...
Thanks

 

[ServinginEcuador]

Since it is solid state the output resistance is probably near 0 ohms. Your best bet is to play around with a couple of different values of resistors and see what you hear. 120 ohms is close to an ideal amount of resistance, and why the Corda comes with a 120 ohm headphoen jack, so start there and work your way down to about 80 ohms in 10-20 ohm increments.

Once you decide upon a good value that sounds best to YOUR ears, you got a winner on your hands!!! Keep it and enjoy!!!

Try reading this thread by Number9 to see about how to improve on the sound using resistors:

CLICK HERE

 

[mecano]

thanks servinginecuador

the thread is great!

 

[sacd lover]

I dont know the regular obh-11s impedence, but the obh-11se is as follows: se rev A jacks 100ohms/220 ohms

se rev B jacks 30ohms/68ohms.


I would guess the regular 11 is around 100 ohms as well.

 

[zoboomofo]

SACD lover is on the right track. If you insist on a Creek obh-11, then please only consider the SE unit.

2 reasons:

1)regulated power supply is standard (so better bargain than its less fancy sibling [usually])

2)impedance matching option with 2 different jacks.

I have the regular version, which I'm increasingly frustrated with. I have the obh-2 regulated power supply which is standard for the SE - it is a needed upgrade to me for imaging and cleanliness. The obh-11 sound is meaty but not at all dynamic. Its sound is wide, but stays wide. The treble lacks the engaging quality that I'm enjoying from the Apheared 47 (and the sound isn't as warm either).

I listened to an SE unit yesterday with a pair of Senn. HD 600s. There's more ambience and elegance in their sound out of jack 1 than jack 2. Jack 2 sounds more forward and 2D like my own unit - not good. On that note, I can verify that impedance matching is audible, but I don't think you'll get the best use out of it with the obh-11 (sorry Creek guys) unless you want to pry that op-amp out for an upgrade a la DIY. I haven't tried it but myself, but with a decent soldering station I would.

EDIT: oops, your profile says you've already got a Creek amp. So why not do another tweak to your system and research another op-amp?

 

[rawhit]

zoboomofo
i think the creek is a discrete design so no opamps. Changing to better quality caps may be an option though.
cheers
RawHit

 

[ServinginEcuador]

Quote:

Originally posted by sacd lover I dont know the regular obh-11s impedence, but the obh-11se is as follows: se rev A jacks 100ohms/220 ohms se rev B jacks 30ohms/68ohms. I would guess the regular 11 is around 100 ohms as well.

Just a quick question: how did you measure the impedance of the output stage?? OR are these figures from Creek??

Thanks!!!

 

[sacd lover]

These numbers are from Creek. Their designer was on head-fi one night and supplied the impedences. Maybe someone remembers that thread. I remember because their is a revision A and B of the obh-11se. I think his name was Alex Nitkin.

 

[akar]

http://www4.head-fi.org/forums/searc...earchid=248727

 

[ServinginEcuador]

Awesome job guys!! It truly is very difficult to read teh output impedance of a solid state circuit!! Thanks for the correction and info about Creek stuff.

 

[mecano]

Well I bought the regular creek because I can use both PSU s the small for travelling.its very cheap in my country I bought the OBH-11 and both psu’s for 170$.i like it a lot: small size and solid detailed sound -I prefer it much more than the x-cans(which I find rather harsh especially with Gradoes and the tiny pot is silly)
As for modifying…now my creek has four Clearaudio RCA’s with silver cabling inside and I can tell you the sound is now more open the highs more extended .
The second I m thinking is yes a caps upgrade.

 

[zoboomofo]

Excellent, mecano! What do you have in mind for caps? Please tell us of any developments with the caps. Does anyone know which op amp the obh-11 uses? I'm certain it was mentioned on the boards, but I can't find the blasted thread!

Rawhit, thanks for pointing out the componentry difference b/w the 2 headamps. I should have said "2 MAIN reasons for me". There IS an opamp in the regular version tho right??

- aw hell, let me open the bitch up.

 

[zoboomofo]

Laziness is certainly holding me back from my diy quest for a good amp. I just opened up the Creek to find out the componentry specifics. Rawhit, it turns out that the plain vanilla obh-11 runs off of what looks like a Texas Instruments chip (Burr Brown?) judging by the logo. I believe the model # is NE5532P -for my own reference, too. I should have remembered that. The number is familiar. I've got a big-ass Samwha Cap @ 2200 uF. There's a few smaller unidentified electrolytics, and some teeth shaped ones - for those in the know

.

My unit looks pretty consistent with Pink Floyd's pics, but mine had a bit of a nasty soldering job on a revision. The soldering is clean, pretty, and not burned except in the joints for Q4,Q3,Q104,Q103. <-What are those thingys, transistors? Mecano, good luck on the further tweaking. If you're looking for Elna Cerafines and can't find any in Greece, then you might be able to buy some on this board. I've got some (in the wrong values) bought by Mr. 'erix'. I don't know if he still sells 'em, but I'm sure he knows who does. Tangent might have Wimas to replace the teeth thingy caps. Holco resistors are available at partsconnexion (dot com?). Adios, amigo!

 

[mecano]

i m not that good with DIY but I have a friend who is capable at electronics and a hi-fi fanatic as well(has a wadia/krell/jm lab utopia system!)he treated my OBH-11.With the 4 big gold ClearAudio RCA’s the creek surely is now a much sexier little beast!. The next step im going to do with my creek/beyer combo:
Change the flimsy ¼ jack with Neutrik gold plated.(NRJ6HM-1-AU-that’s the code at neutrik.com)
Change the awkward coiled stock cable of 931 with Mogami Neglex: http://www.mogamicable.com/mogami/quadmicc.html

unfortunately I can t find a good quality gold plated 1/4 jack.does such a thing exists? Neutrik and Switchcraft are
only nickel.even Cardas and Equinox use them Clou is the only one with their own ¼ jack but is this available separately?
As for the caps he told me the ones inside are rather poor looking so I will definitely change them(erm… I mean he will when I convince him with some nice hard-to-find vinyl!) .i ll ask around in Athens about what caps I can find here.

Cheers
Mecano

 

[tangent]

To clarify some bits of zoboomofo's last post:

- The OBH-11 uses a TI NE5532 as a gain stage and an arrangement of 4 transistors (that's the Q parts you noticed) as the output buffer. The 5532 is a really common op-amp in consumer audio, due to its very low distortion. It's not the best op-amp in the world, but it's pretty good. An OPA2132 is probably better, though, and certainly the higher-end op-amps popular around here would be still better.

- The OBH-11 SE is completely discrete.

- No, I don't have Wimas suitable for modding Creek amps.

Quote:

Neutrik and Switchcraft are only nickel

Au contraire. Neutrik jacks are commonly available with silver-plated contacts. Silver is a better conductor than gold, and although it corrodes, the friction of inserting a big 1/4" plug into the jack scrapes the corrosion off. The same thing happens with nickel, actually. Another plus for silver is that it's harder than gold, so it lasts longer.

There was a thread at Headwize a month or so ago where antness revealed where he obtained the gold-plated version of the NJ3PF6C, if you really want it. Perhaps that place would offer one of the smaller jacks suitable for stuffing into an OBH-11 enclosure. I doubt that you could get an NJ3PF6C into an OBH-11.