Does anybody know if the 990 has op amps in the analog path ? I was reading the latest newsletter that stated "the 970 includes premium op amps in the critical analog path". It made me wonder about my 990. I have some BB opa627 and was wondering if I'd be able to use them in the 990 if it would be an upgrade in sound quality.
Thanks,
Rob

You might be able to bounce this idea off of Outlaw, but it's not something I recall hearing any specific information about previously...

Scott- Any ideas ?

In case Scott misses this thread (which is possible since Outlaw monitors the forum but keeps their active involvement limited, as they try to leave the forum to go where it wants to), you might drop them a note via their support page . It's likely to get a faster response.

Gonk, thanks for the idea. It generated a quick response from Scott. Here is a cut and paste of his answer.

I'm going to do some research to see if I can replace them (if it makes sense) with some BB opa627's. I'll have to use an adapter board if I decide to try it.

Take care,
Rob

NJM op amps are low grade, they sound like crap

Rob - If you decide that it makes sense to try changing out and do go through with it, let us know how it turns out.

From my experience with the 990, "crap" is not a term that I've had reason to associate with it.

Lizard King,
"Crap" is a bit strong. The LM741 is crap. The NJM 2068M is not the best dual opamp out there but its inexpensive and has excellent noise performance and good linearity for the audio frequency range.

Rob B,
The opa627 is an excellent opamp with high slew rate. The opa637 may be a better replacement but you need two opa627's or opa637's to replace one NJM 2068M since its a dual. And you'll have to make up an adapter board which will be a bit of a pain for sure. On the other hand, you should be able to find a dual opamp with better specs that uses the same standard "dual opamp" pinout as the NJM 2068M. If I get a chance, I will look into it some more but, I cant do it right now - heading out to dinner with the wife and she is breathing down my neck!!!

Let me tell this. I have the Denon 3930CI DVD player. This is a very high end unit. The analog output stage is loaded with op-amps (NJM. I had my unit modified and now I have an all discreet output stage and no op amps or caps in the path. The stage has is own power supply including a toroid transformer. The power supply is mounted outside the unit.

Let me say that my DVD player no longer sounds like a digital one, it is now analong sounding!


Op amps SUCK in the signal path!

Lizard King,

Just wondering who did the modifications to your Denon. I used to own an APL Hi-Fi Pioneer 563A where the op-amps were removed and the switching power supply was replaced. The Pioneer went from digital sounding to analog sounding after the mods were done.

I don't claim to know enough about electronic circuit design to speak to the characteristics of a given op amp. For that matter, I don't know enough about circuit design to speak to many of the issues involved in using or not using op amps in the first place, except to say that you need something - and if it's not op amps, it's going to be discrete circuits that are going to add some (potentially appreciable) cost. It does seem worth pointing out the drastic scarcity of processors, receivers, or source components that don't use op amps. As already mentioned, the stock DVD-3930CI (with a list price of $1500) uses them. The Anthem AVM family of surround processors (AVM20 through AVM50) and Anthem Statement processors (D1 and D2) use them. The Lexicon MC-12 uses them. (For what it's worth and in light of some of the earlier discussion here, I also thought it was interesting to note that both Anthem and Lexicon are using Burr Brown op amps - specifically either the OPA 2132 or 2134.)

A bit of googling did turn up at least one home theater component that was designed to use discrete circuits instead of op amps: Lexicon's RT-10 universal disc player. Of course, the RT-10 also had a list price of $3500 and faired poorly in Secrets\' video benchmarks . It's successor the RT-20, with a list price of $5000, retained this audio design but improved on the video performance. I have no doubt that other op amp-free designs are out there, but if the price tags resemble the RT-10 and RT-20 I'm not going to lose much sleep over them.

http://www.sacdmods.com/index.html

FYi, this is now his reference machine, the Denon 3930Ci!

Lizard King,

Thanks for the link.

you are welcome. Should you contact him, mention Paul referred you.

rob b, let us know what you think when you change the op amps out.

Usually people who say things like "op amps don't belong in analog circuits" fall into one or both the following categories:

1) People trying to sell something
2) People who are unqualified technically to make such statements.

At least it's not as obvious as folks selling $1000 wire.