Replacement EF86 - quiet / low microphonic

DesignTaylor

DesignTaylor

New member
Hey gang, just snagged a used Eros to add to my rapidly growing (doubled!) Bottlehead collection. It has a wonderful tonality, super sweet, but I'm also getting a ton of background noise. I'm thinking these are primarily microphonics and environmental interference being picked up by the tubes. They all get louder as I crank up the volume.

From my research to date it sounds like reducing vibration is key so I will be adding more dampening to my equipment stand and maybe try some silicone o-rings on the tubes.

I'm also wondering if there are some better EF86s I should try. I've read all I can find on the forum but not nothing conclusive regarding low noise performance. The Telefunken EF86 and Genalex Z729 seem to be very well regarded but have gotten crazy expensive. The E80F Valvos seem promising but I'm not sure how well they control noise.

Let me know if you've found a tube you really like that's more reasonably priced.

Thanks!
 
Currently, my cartridge is a Shure M97xE, although I have a few others on hand if needed for testing (Nagaoka MP-110, Audio Technica AT 13 Ea).

I believe that all the tubes are the original stock ones (EF86, 6DJ8, 12BH7).
 
I should also note that what I'm mostly hearing is hiss. Sometimes it kind of pulses or sounds a bit percussive (with no input). Worse if the TT is not connected I think. I'm guessing I'm off base with the microphonics (just such a fun word).
 
That's a 4mV nominal cartridge, which is plenty good output-wise. That rules out too low a cart output for the preamp being an issue. Hiss is generally a tube thing, and generally you just have to find a quiet tube by trial and error.
 
If the Eros was used a lot, the EF86s may be worn out and noisy.  I have only ever seen this in one or two of the oldest Tape Repro amps that I have serviced that were used a ton. 

 
Even the primo tubes can be noisy. You just have to try them. You may pay more but be able to return a noisy tube if you buy from a specialist tube dealer. Or you can buy a few Soviet tubes (6n23p, 6j32p) from ebay sellers and pick the best of the batch. They sound quite good.
 
Got it, thanks for the advice. It seems that leaving the Eros on longer seems to quiet it down a bit... does that sound right or I'm I just telling myself what I want to hear? I also noticed that right after I lift the needle off the record the Eros is very quiet but as I let it sit without playing it starts to get louder and I head the little pitter patter super soft popping start to get louder again.
 
Leaving it on may indeed keep it quieter.

Pitter patter reminds me of the noise that can be picked up from certain cell phones and wifi routers. 
 
ah ha! it is pretty close to a wifi router... I was wondering if it didn't need more shielding.

Is it better to shield close to the tube (like putting a copper pipe around it as a rudimentary idea), or try and put a divider, or cage of some kind? I know the best move would be to move the router but I have limited layout options. Unfortunately, I've got a bunch of electronics all sharing the same corner.
 
DesignTaylor said:
Or is it really the cartridge that's picking up the signal?
Click to expand...
You can unplug the tonearm wires from the Eros, then cap each RCA jack with a little piece of aluminum foil, then evaluate the noise. 

The best option is increasing distance between the router and Eros, if that's the cause.  It is certainly worth your time to power down the router and reevaluate the noise again.
 
Did a little testing last night. Moved the router away and put my phone on the other side of the room. I'm not sure that it made a huge difference. I also added some isolation feet to my component stand to try and reduce vibrations (old house with bouncy floors). Again, no obvious result.

What I will say is that the longer I leave the unit on the better it performs. After about 30+ minutes you still get some warm hiss if you crank it but the pitter patter is pretty much gone.

While I'd love it to be a little quieter I'm mostly happy with how things are sounding. The Eros does seem to emphasize the noise floor of my records more than my previous phonostage but that may just be the tradeoff for the extra richness I'm now getting. Or maybe an alternative cartridge would do better.

I've got a pair of NOS Westinghouse EF86 on the way so we'll see how they do as well.
 
Further update. I have the new Westinghouse EF86 tubes loaded into the Eros. They are much, much quieter, and seem less susceptible to interference but so far sound a bit flat (megaphone tone) to my ear. They've only got 6 hours of burn-in time so we'll see how they shake out.
 
Haven't cleaned the contacts yet, I will give that a try. I ordered some DeoxIt... any other recommendations?

Here's a crazy question that probably warrants its own thread... does humidity impact tube performance? I've always noticed that when it gets cold out and the air gets dry (and the central heat is running more) I get a lot more static on my records and things just tend to sound noisy. Recently, I've noticed that my previously very quiet Westinghouse EF86s are way noisier since it got colder and dryer out. Is there anything to that or is it just a day to day performance difference?
 
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