feedback resistor value question

[KevinLee]

Hello,

In the pre-amp section of my integrated amplifier there are (2) 17k8 resistors which are the feedback resistors. 1 for each channel.

I cannot find a good quality 17.8k resistor. What will happen if I change this value slightly?.

I was thinking of 18k.

Is it a worthwhile cause to upgrade this resistor to a caddock or vishay?

Any input or experiences would be appreciated.

Thanks
KevinLee🙂

 

[mFinalHeaven]

I am not sure about the circuit you are using, but usually such a small difference is minimal.

 

[analog_sa]

Nothing much will happen. For peace of mind you should check the resistors which tie the - input to ground in order to calculate the gain but the change will likely be minute. Resistor sound is very much a personal choice and you should buy a few different makes and experiment in order to take the right decision.

 

[peranders]

Hello,

In the pre-amp section of my integrated amplifier there are (2) 17k8 resistors which are the feedback resistors. 1 for each channel.

I cannot find a good quality 17.8k resistor. What will happen if I change this value slightly?.

I was thinking of 18k.

Is it a worthwhile cause to upgrade this resistor to a caddock or vishay?

Any input or experiences would be appreciated.

Thanks
KevinLee🙂

The difference between 18k and 17k8 is 0.09705 dB approx. = not very much

Vishay makes good and normal industrial quality resistors, work good in most cases.

What type or brand did you have now?

 

[KevinLee]

Peranders,

Right now there is only the stock metal film in place.

The feedback resistor is tied to ground with a 1K metal film.

Should I also upgrade the 1K resistor?

Thanks

KevinLee🙂

 

[peranders]

Peranders,

Right now there is only the stock metal film in place.

The feedback resistor is tied to ground with a 1K metal film.

Should I also upgrade the 1K resistor?

Thanks

KevinLee🙂

Seriously I don't think it's worthwhile only to change two resistors. I think the active elements (opamps?) are far more important.

 

[KevinLee]

Hello,

What are peoples favorite resistors for this application?

Caddock MK132, Tantalum, Vishay Bulk metal Foil, Draloric SMA-0207, Vishay CMF Type RN, are all types I am considering.

Any preferences of the above types for feedback circuits?

Thanks

KevinLee

PS. I am using OPA627 as my opeamp.

 

[analog_sa]

Should I also upgrade the 1K resistor?

You should although IME the fb resistor has the strongest sonic influence
Only your own ears matter in selecting the resistor types
Btw 627 is seriously overrated sonically

 

[KevinLee]

analog_sa,

I have just installed the OPA627 via Brown Dog adapters and am letting it break in now. You are right that I might not like it. I previously had a AD826.

What is your choice for op-amp in pre-amp stage?

Thanks

Kevin

 

[peranders]

Btw 627 is seriously overrated sonically

Maybe so, but still excellent!

 

[Nuuk]

FYI, The Welwyn RC55's which are very good resistors are available in the 17K8 value. (Farnell order code 340-376)