Creek Audio OBH-11 Headphone Amp Upgrade

[bigskyaudio]

An excellent linear regulated power supply is here:

https://www.jameco.com/z/DFU240050D...gle-Output-24-Volt-500-mA-12-Watt_174861.html

 

[adydula]

This unit has the resistor from the case of the vol pot as well

 

[bigskyaudio]

All the later production units have this but we added it to older versions.

 

[adydula]

I was just looking at that Jameco.
Parts ordered via Mouser.

So I will remove stuff clean up the board and wait for the parts!
Anxious to see how this will work out vs my other stuff.

The amp here had a lot of noise from about 1/2 way up on vol pot.
But things were so loud it was like a dont care.

Alex

 

[adydula]

Ok all parts desoldered and removed!
Parts hope to get them by the end of the week.
The op amp maybe early the following week.
Should only take a few hours at best to reinstall and solder.
24vdv Jameco ordered.

Stay tuned.
Alex
thanks to all for the help especially BigSky!!
:>)

 

[adydula]

So far:
Waiting on the PRP's the 4 30 ohm ones.
Holcos are in and the 2604 is in.
Prior to changing all the caps it was very noisey with the vol pot 1/2 way.
Now its dead silent all the way up!

Listening now with X+ZMF VC's high impedance cans and it "Superlative!"..

Such a wonderful amp from 2008!
Amazing beast!
Alex

 

[bigskyaudio]

Good work Alex! The OPA2604 is my absolute favorite opamp and they sound spectacular in the Creek OBH-11. This mod was developed over many months of parts swapping to find the right combination. There is a nice increase to clarity and detail.

 

[adydula]

MIchael sent me both Halcos and PRPs for the 22.1K's to try.
I installed the Halcos..
The other 1K and 30ohm PRPs i got from Parts Connexion in Canada be here tomorow.
Dont know if they will make this any better than it is.
Using the Jameco 24 vdc linear as well...
Stands up to most otnher amps I have seriously for this price and age...its amazing.

Thanks much for you help!
Alex

 

[bigskyaudio]

Stick with the Holcos for the 22k feedback resistors.

 

[adydula]

Ok with that!
In your list it shows PRPs for R1 and R101 1K,
and the r9 and r109 and r10 and r110 as PRP's
Did u change yours to these?
Alex

 

[bigskyaudio]

I only did the R1 (R101) 1k PRP and R11 (R111) 220Ω PRP along with R6 (R106) 22.1k Holco H4.

You can probably leave C6, C106 = 22pF (47pF in early units) polystyrene or mica out of the circuit with the OPA2604 but they are absolutely necessary if you ever want to reinstall the NE5532. I left them in on my amp.

 

[bigskyaudio]

Remarkable sound out of a nice small amp that one can actually work on. Very upgrade friendly. The guys over at head-fi think it's crap though.

 

[adydula]

Yeah thats a long time ago for this amp, and with so many other better spec'd and more high power amps this has fallen by the wayside.
IMO its still really a decent amp that changes very much for the better with these mods..
Parts do matter!
:>)
Alex

 

[adydula]

Got all the parts installed.
Listening here.
Absolutely stunning...

 

[adydula]

The specs for the 2604A are 12 v and 35 mw, so this is approx 420 mw at 600 ohms?

With the 300 ohm ZMF cans I only have to use 4-6 clicks of the vol pot for very loud listening.

Amazing amp..

 

[SMUSA]

I see few versions of this amp:

Music Hall HA11.1 - Available new and guessing rebranded version of OBH-11? Do the upgrades mentioned here will apply to this?

Creek Audio OBH-21SE: @x-pro has shared the schematics.

Creek Audio OBH-21 MK2: @x-pro - I am guessing this is later version of OBH-21 but not sure how it compares to 21SE etc.?