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Old 3rd May 2006, 11:17 PM   #1
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Default Opamp upgrades for Pre Amp?

Hi peeps

I have a rotel RC960BX pre amp, I was just looking inside, more of a newby tinkerer than a full on DIY system maker But I was thinking maybe I could get a better performance if i upgraded the opamps?

Heres the list of current opamps..

on the left near the headphone inputs is a JRC 4556D

what seems off the tone controls is a Signetics NE5532AN

and then in the centre just off the volume switch is another one exactly the same (Signetics NE5532AN)

Now near what im sure is the phono preamplifier stage?? is 2 Signetic NE5534AN, and two TL071CP.

(could it be, that one set is for MM, and the others for MC?)


I have from trying different opamps in the Cd player, have these Opamps, spare

BB OPA604AP times 2

BB OPA2134PA " "

BB OPA2604AP " "

AD OP27EP IC " "


Would any of these be of good improvement over the stock ones?

A bit irritating but it wont let me upload the photo of the insides of the Amp , even though the file is 400KB?

thanks for any advice or help
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Old 4th May 2006, 12:36 AM   #2
lndm is offline lndm  Australia
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There will be many opinions here I suspect, but I think the NE5532AN is a good choice and should be left in (at least until you've tryed the others). I would start with the 4556's. Then I would approach the TL071's (which are probably in a low noise application).

I think the OP27 will be better than the 4556, but not the 5532.
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Old 4th May 2006, 01:13 AM   #3
infinia is offline infinia  United States
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Can't say for sure until we see the schematics. Op-amps like all other components are application dependant/specific.
But YMMV
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Old 4th May 2006, 08:27 AM   #4
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I know what your saying about them being dependant on other applications, point taken, i was just wodering with the experience of those that know of a like kind OPamp.

Thanks for the info Indm, and the advice Infinia. Cant find a Schematic for the Rotel anywhere.

Was kind of hoping for a simple drop in, here and there, but im srprised the NE5532AN, is one of the best, but, this preamp did however only retailing for 150/$300, did turn the heads of HIFI Choice, and they can be quite damming. Makes me wonder if im going to make any vast improvement. Still all info is welcome
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Old 4th May 2006, 08:56 AM   #5
infinia is offline infinia  United States
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hi
Since you are looking at loads of choices for op-amps, you could obtain the data sheets for the pin for pin types and rank them in order of SR , (e)n, (i)n & GBW specs. Use the data in a chart format as a basis for your initial selections.
Finally conduct listening evaluations. Come back and publish a report.
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Old 4th May 2006, 08:57 AM   #6
lndm is offline lndm  Australia
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I just remembered this.

It is IIRC seven pages and IMO very interesting considering your current needs.

http://www.zero-distortion.com/tests/opamps/opamps.htm
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Old 4th May 2006, 06:31 PM   #7
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Guess what ive just been doing?. I have taken out the stock amps, and replaced more expensive ones of the same ilk, checked all the polaritys, and for the same designs.

I replaced the JRC 4556D with a BB OPA2134PA

the two Synetics? NE5532AN's I replaced with BB OPA2604AP

I havent as far replaced what i think is the phono stage TL071CP,

And the SYnetics? NE5534AN, i have some Analogue devices that match these..OP27EP they are quite expensive. to be honest i use the MM stage, if one set are for the MM, and the other for the MC, i would prefer to replace the MM. As i dont have a MC cartridge for now, but I dont really know if they work in series of two together, or seperate,

So far....
It all sounds marginally better, no real wow factor, the opamps were decent enough, but there is definitely an air of detail and richness in the sound, and a tad more weight. i had noticed, from CD to Amp, that the playback through headphones in the Amp, sounded ever so slightly shrouded, a bit cold sounding. Now its what i call richer and full. through speakers as well

Perhaps thats the Burr Brown touch.

Im pretty annoyed i cant upload a simple pic of 400Kb

Im really looking for a decent upgrade for the TL071CP now

I'll be totally honest infinia, you know those monkeys they trained to fit the square block into the square hole, and the ball into the round one. thats my understanding of electronics. i can make an amplifier if someone shows me, but on my own I dont have the nouse or the focus to understand schematics.

Ive fixed synths and quad amps, rehoused a T amp, and Im just really finding a project, thinking how can that work, or whats the simplest way to make it sound better, and just learning the bare basics.

heres my technical knowledge, if i see the PDF Opamp diagram matches up with one ive already got , it might not blow it up!!, lol

but im learning all the time, also not to get out of my depth, this preamp cost me 40, so if i screw it up, even though im On invalidity benefit, Its no great loss. And if i do get electrocuted, maybe, the Shock will cause my Arrythmia to leave

As always thanking you all for advice, but miffed i cant upload pics only 400KB's
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Old 4th May 2006, 06:59 PM   #8
VEC7OR is offline VEC7OR  Lithuania
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In general it safe to exchange FET input opamps with FET input and BJT with BJT. I would replace the TL071 first, as they rather mediocre and bit noisy. As people previously said, I would agree to leave NE5532/4, as its rather good opamp, some people recall it a bit bright, but I like it as it is.
In phono stage you will prefer something lownoise but it depends on the system you are using as some opamps have low current noise and some have low voltage noise. I would try OPA604 in place of TL071.
You also can browse http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm for more info.
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Old 4th May 2006, 07:59 PM   #9
anatech is offline anatech  Canada
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Hi emperor,
The 4556 op amp is designed for driving headphones. You should reinstall the original part. It can drive lower impedance loads than even the 5532.

-Chris
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Old 4th May 2006, 09:29 PM   #10
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Well the OPA2134PA sounds better than the 4556D, will it cause a long term problem though?
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