ESP Phono Preamp Project

[sml1226]

I've got a few things I want to verify/clarify/decide prior to ordering some parts. With RadioShack being my only local option, I don't really have an option but to order these parts.

What would be my best way to run the amplification stages? 4 single channel op-amps, 2 duals (one per channel), or 2 duals (1 stage, both channels per DIP). 4 singles obviously means more components, but if there would be an improvement, I'd happily use the extra space.

Second question, in something like this, how much, if any, difference will I be seeing with a toroidal transformer as opposed to a standard one for my power supply? It's about twice the price for one, but within my budget, so either works.

Last one is more opinionated. I've seen multiple op-amps mentioned in the pages on this particular design, and was wondering, with the CMoy op-amp rolling, is there any particularly good one (favorites anybody?) to use here? The OPA2134 (if I go dual op-amps that is) is one in particular that has been recommended.

I need to move from this cheap integrated phono stage in the old receiver soon, any input is welcome.

 

[Avro_Arrow]

Digi-key and Mouser are your friends...
 
For a phono pre-amp I might pick AD8597/AD8599.
Another option might be the more modern version
of the OPA2134, the OPA1641/OPA1642.
As for duals/single. As you mentioned, singles will
give the best performance and sometimes a better
layout. Sometimes duals give a better layout and
are cheaper per amp. I would go with singles myself.
A standard transformer will be just fine. You will be
using a well filtered/regulated power supply,right?

 

[sml1226]

Alright, singles sounds like it will be better in the end. I think I want to keep with the DIPs though. I don't want to order adapters yet to be able to mix it up with some amp-rolling, so I'll go with the OPA134, and maybe try some others down the line when I can justify the little tweaks of others.

The power supply circuit looks like it should let me use a standard one just fine. Sadly Mouser has nothing with the proper amperage and mounting style that's not overkill, so I'm going with a toroidal one. I'm not ordering that alone from somewhere else as shipping savings will cover any savings on the base price of another dealer.

Looks like I can order some parts and get to work here pretty soon then. Thanks

 

[sml1226]

Building in progress...

Currently I have something failing somewhere.

The speakers hum pretty badly when the ground wire is connected to the RCA jack, but when the wire touches the ground portion of the RCA plug instead, it goes perfectly silent. Could it be the jack, the joint, or is this as confusing to veteran builders as it is to me? I don't see why it should go silent when it is connected to the plug when the jack allows so much hum.

When I was wiggling connections to see if I had a short or something (while holding the wire to the RCA plug to stop the hum), I bumped the power supply and noticed it popped a bit through the speakers. When I touch any metal on the supply, that's not in the path directly itself (cap tops, heat sinks, etc), it basically acted as a microphone. Occasionally this would trigger about a 3 second burst where the music would play, but it sounded amped, with no equalization.

It's really not making any sense to me, every component is still at its rated value when tested, continuity through each joint seems fine, and the output is even at a higher voltage than the input, however I'm getting nothing but the hum.

I thought at some point that my amps were blown and in need of replacement, so they will be regardless of that being necessary or not, but can anybody give any input on what may be wrong with this thing if that doesn't help?