rc4558p replacements?

[nvrgdenuf]

Loooking for a good replacement for these. Located in the I/V section of my Shanling, I replaced with the opa2134a which improved the bass/mid bass significantly, after........... they quit oscillating and squealing. I read the AD823 may be a good replacement.... but may oscillate also. Or would a small cap across the + and - take care of this? If so, size and type recommendations?
thanks
andy

[mjf]

hello.
perhaps annother trialnce i changed the rc4458 to ne 5532, mc33078, and lm833 (all bipolar opamp as 4558).
a small cap(47nf or 100 nf) across the v+ and v- (supply) often can help.
greetings.................

[FastEddy]

mjf: " ... a small cap(47nf or 100 nf) across the v+ and v- (supply) often can help. ..."

Good eyes, good tip, MJF ... Make them plastic / poly type caps = as "close coupled" as can be easily done = close to the power pins of the Op-Amp.

This is the Texas Instrument trick for decoupling and significant reduction in PS noise = better PS filtering = a good trick and it really works = thus it makes Texas Inst. Op-Amps look real good. ... National Semi recommends this too. (Read Bob Pease' reports on Op-Amp filtering and the noise reduction quality of plastic caps @ ti.com and elsewhere.)

[mjf]

[QUOTE]Originally posted by FastEddy
Good eyes, good tip, MJF ... Make them plastic / poly type caps = as "close coupled" as can be easily done = close to the power pins of the Op-Amp.

thank you,dear fasteddy.
e.g. in europe wima capacitors are easily available: wima fkp2(a mkp,polypropylene,little green ones),
and the cheaper wima mks2(mkt,polyester,the small red )-the 100nf/63v worked always properly and it sounds quite well for that money.
greetings.......... mjf

[FastEddy]

" ... wima fkp2(a mkp, * polypropylene *,little green ones), and the cheaper wima mks2(mkt,* polyester *,the small red ) ..."

On a "one up" prototype or home brew device, I never pay much attention to capacitor costs, since most are within +/- 20%. I try to use the best available without digging into the "audiophile quality" types which can get outrageously expensive.

I buy the yellow (and red) MKT type by the handful for power supply applications, but try to use the plastic poly type close to the Op-Amps. ... As Bob Pease says, the poly types may be best, but chasing that last five percent of quality (or price) may never be worth the "step and fetch" costs ... not worth the efforts.

Another power supply noise trick is to parallel a lesser value poly / MKT type across the electrolytic barrel type caps = If 100 uF 'Electro, then add 1 uF to 10 uF yellow MKT in parallel = this can add a few dB to the noise rejection ratio =

DO USE the little red and/or green polyester or polypropylene type if available, but "settle" for the bigger, yellow MKT type if the other is hard to find = no problem found =

[mjf]

hello fasteddy.
the yellow ones are the wima fkc ( mkc,polycarbonat)-recommended for fast digital circuits......and the blue ones fks-2 too.
greetings...............mjf

[FastEddy]

Yellow verses blue, green and red ... new info = thanks.

Someone should write another monograph on the different types available ... You?

I would be very interested in it.