Frequency Response Contour Changed on Old Electronics?

I've been making needle drops for several years now using my Marantz 1090 integrated amp, and recently I noticed that my needle drops are much bassier than they were in the past. Occasionally this old amp does funny stuff where a channel might short out briefly but then it always comes back on again right away, so it does need to be serviced. So I'm wondering, can the frequency response of audio electronics change over time as the electronics get old and maybe start to wear out? @Tony Plachy, @chervokas?

 

Electronic parts can and do drift out of tolerance with age, and this affects how your amplifier sounds. Your amplifier needs servicing.

 

Probably old caps that need to be replaced.

 

Which do deteriorate with age. The originals are most likely bad, the way you describe the amplifier sounding is a major indication of the electrolytic caps going bad with age.

 

Dirty switch contacts and jacks affect frequency response on a large scale. I am always amazed by the improvement when doing my standard service/ cleaning on an old piece of equipment. (I am a "deoxit-free" technician for the preservation of good OEM parts) Another problem can be out of spec electrolytic capacitors. Less common are out of spec resistors, even a slight drift of more critical bias resistors can affect frequency response/ dynamic headroom, etc.

 

Yes, and any good repair and restoration regime involves cleaning every dirty pot and switch. And that previous post has solid advice which is well reasoned.

 

Wait - nobody uses an amplifier for needledropping! Maybe you're just using the phono stage section? But what are you using as an A/D converter?

Or are you saying it's the playback that's getting bassier? In that case it's surely nothing to do with your needledrops - it's everything you play back through that amp.

So many questions...

 

My 22 year old B&K EX4420 started to get muddy and dark. The final straw was it sounded like a corn popper every now and then. It's sitting on a shelf now.

 

It's an integrated amp, so yes, I am not using the "amplifer" electronics for it, I am using the amp's phono stage.

You're right that it could be a number of things but I have a strong suspicion it's the amp.

The funny thing is I don't really notice the increase in bassiness when I play back through my speakers so it may have something to do with the "preamp out" that I'm using...? Anyway, I figure I'll start by getting the amp serviced.

 

You can probably just get the phono stage recapped with 5%+ tolerance capacitors similar to the original specification. I had a Parasound preamp that had significant deviations from RIAA likely from 30 year old caps.

 

Like everyone said, anything can go out of tolerance 30 years down the line, especially capacitors, and especially electrolytic capacitor which almost certainly are out of spec after 30 years, and yup, that can have an impact of FR, or noise, or whatever depending on what parts are going south where in the circuit

 

I have here two 1978 Pioneer SX-780's. One has been recapped and the other is bone stock.

The recapped one is crisp, clean and a bit lean, and the stock one is rather thick and not as detailed.

 

You guys rule, thanks!

 

So when making the needle drop are you using one of the tape loops to take the phono stage output to your recorder (what ever it is)? If the 1090 works like most amps of its day when using a tape loop all of the amps line stage controls are out of the loop, so as said above it is really just the phono stage that is being used. How do you play back the needle drop, is the 1090 used for playback?