[guest1632]

I am thinking in the hopefully near future to getting one of these Hypex ampts. However, I want to convert the place used for an AD8620 which if I understand correctly is a dual opamp, to a single 627 amp. One has 8 legs, and the other has four. It can't be that hard to do the PCB conversion. I don't wantta use any adapter and maybe muck up the sound. So is there a chart to cross wire the 8 perminals/holes to use only four? To give someone even more of a challenge, can you describe this on a verbal basis? I am a blind person, and as hard as I might, can't see the pics. Thanks for the help.

Ray

[Occam]

Ray,

I'm unsure as to your question. Like the dual opamp chips used in the UCD, the single opa627 is also a 8 pin chip. On the single, the pinouts are different. I believe the UCD makes use of both opamps within the dual opamp ad8020, so replacing it with a opa627 would require an adapter such as the brown dog adapter from Cimmaron Technology -
http://www.cimarrontechnology.com/index.asp?PageAction=VIEWPROD&ProdID=19
or
http://www.cimarrontechnology.com/index.asp?PageAction=VIEWPROD&ProdID=20

The first would allow you to adapt 2 so8 (surface mount) single 627 to a dual so8 output, while the second would allow you to do the same using dip8 form factor opa627 s.
I'm unsure as to the clearances around the UCD's SO8 pads, so I can't give you any assurances that these adapters would actually fit.

I'm assuming your intent is to alter the subjective 'flavor' of the amp by changing the dual opamps used. If so, you might consider the following opamps as alternatives, which should be drop in replacemants -

1. OPA2107au which is a dual, similar in technology to the single opa627, but lower speed which might be slightly lower in resolution. I don't know if these technical differences would be subjectively discernable.

2. AD8066 in the R-8 package. Subjectively, this chip lies between the OPA627 and the AD8020.

My knowledge of this is limited and somewhat second hand, so I'll refer you to Tangent (something of a headphone amp guru) -
http://tangentsoft.net/audio/opamps.html

and -
http://www.sgheadphones.net/index.php?act=SF&s=&f=12

I'll also add that the subjective differences between opamps depends greatly upon the specific application and implementation.