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Tube Phonostage Causing Rumble and Noises

Hello, I am desperate in need for advices and help.

I have a Aesthetix I/O Eclipse (one power supply) that I acquired new in 2009. It started to make the SVS SB16 Ultra subwoofer rumble a few months ago. I sent it back to Aesthetix, they performed a bunch of upgrades and replaced 4 tubes in gain stage one claiming these would help with the noises. 

When I got it back three months later, the rumble got a bit better but it was still there. Then Aesthetix sent me a new set of tubes claiming there were specially selected and tested for low noise. However, they didn’t eliminate the rumble.

Then I played a record to during the test, the unthinkable happened. When the phonostage is idle, there was just rumble. As soon as a signal was passed from the phono, the sub went crazy, it produced some subsonic noise that made the room shake. I then connected the phono to a tube integrated amp and I heard a loud distorted noise through my LS 3/5A.

The strange thing is that I have no issues using the I/O with my Apogee Fullrange without the sub.

I would appreciate any shape or form of advice/help.

Thanks in advance and Happy New Year!

agharion
jasonbourne71's avatar
jasonbourne71
1,173 posts
 

Rumble filter needed to attenuate everything below 20hz. In the past preamps often had this as a switchable option. My RGR 4 has it and I leave it engaged.

noromance's avatar
noromance
9,769 posts
 

+1 Could it be that simple? Sounds like a feedback loop.

How loud is your subwoofer set?

When the phonostage is idle, there was just rumble.

agharion OP
9 posts
 

Thanks for the feedback. I asked Jim White about the rumble filter and he said it was a bad idea. I set the sub volume at around -20 dB. Crossing over at 35 Hz for the Apogee and 85 for the LS3/5 A. Definitely not loud.

No issue with the rumble/noise playing the DAC (Bricasti M1 Series II).

I am using XLR throughout except the tonearm cables.

I don’t have issues using the I/o with the Apogee. Maybe it’s because the frequency response is 25-25k Hz and the I/O is generating subsonic frequencies under 20 Hz.

 

 

mlsstl
1,436 posts
 

One issue with LP records is the need for the RIAA equalization curve. Due to the technical requirements of vinyl record recording, for playback, the RIAA curve boosts bass +20 dB and cuts high treble -20 dB to compensate for the polar opposite frequency adjustments made when the master was cut.  This means that rumble and any imperfections in the record will be magnified.

Over at the Propeller Head Plaza section at Audio Asylum (where geeky stuff is often discussed) a fellow posted some screen shots of spectrum analysis he did on various phono cartridges.  On one set of images, the 20 Hz background noise was about -70 to -80 dB, but when you dropped down to 10 Hz, the background noise increased to -39 to -48 dB.   Therefore, if you are running a subwoofer with a turntable and have a phone preamp & amp system that is linear in the sub-bass, it is very easy to end up with playback problems.

agharion OP
9 posts
 

Since the problem persists after tube swapping, I am beginning to suspect there are defective parts in the unit.

when lightning strikes twice, it cannot be just coincidence. Before I acquired the I/O, I got a Rhea Signature. The minute I turned it on, my jaw dropped to the floor seeing the speaker driver cones being pushed all the way out. It was a scary scene. I took the Rhea to a local tech. He did some measurements and concluded the Rhea was generating subsonic frequencies. I informed my distributor about the issue and he didn’t believe me. I took the Rhea to him and he witnessed his diver cones got pushed out all the way. He immediately promised a replacement and I opted for the I/O.

Can anybody offer some information about subsonic frequency coming out of a tube phono that is caused by failed or defective parts?

Thanks.

 

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