Yamaha 550u EQ Opamp Questions? - DiyAudio

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• Yamaha 550u EQ opamp questions?

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• Thread starter Thread starter MoreCoffee
• Start date Start date 2016-01-05 6:39 pm

Status Not open for further replies. Jump to Latest M

MoreCoffee

Member

Joined 2014 I picked this up for free ..Its in good shape ,just one scratchy slider pot on the output level.. But this thing sounds flat and terrible compared to the meager Technics SH8017. I opened this up and found two(2) NJM4558DX and a (1) NJM2068D-D The consensus seems to be that the 4558 can be swapped out with the NE5532 or a OPA2134 😕 The NJM2068D-D is another story.. Trade it for a LM4562 ?? Wish there was a ISO standard for data sheets. Is Unity Gain the same as Gain Bandwidth 😕 Thanks for any response M

MoreCoffee

Member

Joined 2014 The aforementioned Gain levels are not the same..should read more😱 NwAvGuy: Op Amp Measurements

sgrossklass

Member

Joined 2004 stephan.win31.de Can't tell what the problem is without having seen a schematic. Thankfully, you can get one. Mmkay. Forget about swapping out opamps, those are merely used for the mic preamp and pink noise generator. The magic is happening in these NH-0064, NH-0065 and NH-0104 custom ICs. Last time we were discussing an EQ here, electrolytics in the EQ circuit were considered bad form. This has a number of 'em. There's a bunch of what seem to be standard quality polar electrolytics in the signal path here. Wouldn't be surprised if you find that some of them are simply dead. Otherwise it might also be a problem of disconnected ground - any signs of shipping damage? Consider running a loopback test through the EQ with RMAA on your computer. If there's any irregularities in FR or distortion, that should show it right away. Status Not open for further replies. Share: Facebook X Bluesky LinkedIn Reddit Pinterest Tumblr WhatsApp Email Link

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