Op-amp for Carver TFM-45

I read and carefully studied the TFM-45 service manual in order to find out the reason of "hiss" noise and turn-off thumps and squeals. I came across these points:

(a) Page 21 - Bad TL081 op-amp (U1) on Amplifier Board causes "hiss" or "popcorn" noise
(b) Service Bulletin # TFM-45-6: To verify that 4558 IC's (U2) are either
XR4558 (Exar)
RC4558 (Raytheon)
whereby other brands 4558's can cause turn-off thumps and squeals

It is my surprise to see that the U2 op-amps' in my TFM-45 are of Japan Radio Corporation JRC4558D, non of above-mentioned. My question is why TFM-45 was factory-installed JRC4558D, instead of either one of above-mentioned. As both the Exar's and Raytheon's I believe is no longer available in Malaysia, is the RC4558P of Texas Instrument (Made in Malaysia ) identical in performance as compared to Raytheon RC4558?

I searched and found interesting information about the comparison between JRC4558D and RC4558P:

http://www.stinkfoot.se/andreas/diy/articles/opamps.htm

My second question is that will Texas' have less hiss or popcorn noise than JRC? In fact I have bought RC4558Ps' but still hesitate to give them a try. Is anyone here has experience on this regard?

I intend to change the U1 as well.

I'd just pop the RCs in there and give it a listen if the JRCs are giving you problems. Aren't the Raytheons available anymore? There are two TI chips available from Digi-Key, the RC4558P and IP. They cost less than 50¢. Or, you could try upgrading (especially that TL081) with better opamps. I'm quite fond of the OPA134 (or OPA2134). They are a little more expensive, but pin compatible with the opamps you're considering.

I'd just pop the RCs in there and give it a listen if the JRCs are giving you problems. Aren't the Raytheons available anymore? There are two TI chips available from Digi-Key, the RC4558P and IP. They cost less than 50¢. Or, you could try upgrading (especially that TL081) with better opamps. I'm quite fond of the OPA134 (or OPA2134). They are a little more expensive, but pin compatible with the opamps you're considering.

Dear BillD,
OPA134PA is available from RS Components made by Texas Instruments. Sure will give them a try. Is there any difference between TI OPA134 and Burr-Brown OPA134? Thanks a lot.

For that RC4558P, make sure to get the OPA2134 (the dual). The TL081 the single (OPA134). If the originals aren't socketed, I'd put sockets in so you can swap opamps if these don't work out for you.

I remember a thread some time ago regarding this exact topic, but I think it was something that came up during discussion under another topic. Someone replied that there was a service bulletin for this that had a very simple fix for it. If anyone remembers this please chime in...
In the meantime I will look further and see if I can find it. The TFM-45 that is in our main rig has no such issues, but one of our other amps that is a TFM-15 developed a similar turn off issue about a month or so before it stopped working. The problem ended up being the large main cap had bled out. I don't know it the two could be related or not, but I figured it was worth mentioning...

Rainman

Now I recalled that the top side of one of the 2,200uF 80V has very slight bulge comparing to other piece. I always pay attention to all of the capacitors. Could be the reason of turn-off thumps. I shall recap and see if the problem resolve.

My ICs' have arrived today. OPA134PA Made in USA (in fact Made in Thailand) and OPA2134PA Made in Malaysia. I shall change all of them tonight. Eager to know how my TFM-45 will "sing" after modification.

Did you already re-cap as well? Good luck!

Have not recap yet. Only 2200uF 90V available. The original spec 2200uF 80V only available from RS Components which require longer time. Can I use 90V instead of 80V?

I'm not positive about that, but believe that shouldn't be an issue. We have a few resident experts techs who will be able to tell you for sure....give it a few days.

What is the magic have done by all these ICs'?!! Great! I have now very wide, precise and deep sound stage after putting them in my TFM-45.

No more high frequency squeal sound and the hiss noise is very little now. They really work. FANTASTIC!

The remaining problem is turn-off thump.

Congrats

BillD, thank you very much for recommending these ICs'. I suggested that all TFM owners must try out this upgrade.

I have bought shielded power cable Supra LoRad 2.5 for upgrading. Better performance? Any comment?