Subsonics with new phono stage. Is this a comms issue?

[Kneesup]

That may be the case if those phono stages have a rolled off bottom end. Still doesn't rule out the arm/cart combo.

I like your thinking Geoff. I'm not techy, but the new Stage may simply be more 'sensitive' to such issues, in my parlance. What is interesting is that, as Tom said earlier, there can be many contributing factors and I honestly think matters are improved since I went through the process of refining that I have. It seems to be a 'cumulative' issue as much as one created by a single thing. Alas, the core cause remains, of course. Hi Fi is anything but straight forward! Many thanks again to all those who have kindly contributed to this. Richard

[Bigman80]

Geoff makes a valid point there.

My own subsonic issues were introduced when I changed cables, not preamp as I first thought.

It the prior equipment isn't sending those signals, it won't have happened untill something did.

Well done Geoff.

[montesquieu]

Yes there would appear to be an underlying issue but it may be a relatively small one.

I would suggest that the previous phono stages are likely to have subsonic filtering (based on IEC-modified RIAA, or something similar to that approach).

The new phono stage not only has no subsonic filtering but is 3db up at 20hz (no doubt a deliberate choice to modify the RIAA curve and flesh out the lower registers - this seems quite common these days, for RIAA to be manipulated for effect, rather than aiming for a flat response). However the consequence of this is that some previous issue that was either insignificant or filtered out by the phono stage has become very apparent.

The underlying issue may not be a major one. 3db up at 20hz is a lot - every 3db is a doubling of gain, remember. It's obviously a cumulative effect and might well disappear or return to being negligible with a different phono stage. I think Richard is adopting the right approach, optimizing everything else as far as possible, then trying a new phono stage. It could primarily be that that phono stage and that deck don't get along.

[Kneesup]

Many thanks all. Tested with a loan phono stage tonight and no issues at all. So, it’s probably the stage and Robert’s on the case. We’ll sort it one way of another. And I’ll report back. The Robert Airey Worx version of the Black Ice Audio F159 is a giant-killer and I have the first ‘prototype’. So there may be a R&D tweak to do, or even a failed component. It’s called the 159 because it’s designer Jim Fosgate’s 159th phono stage design. And his best. So... I have high hopes for it ultimately. Besides, as is well known on AOS, Robert is as fastidious and he is conscientious. It’s exciting to think sonic quality of this kind is possible at a realistic price. Also my unit has worked perfectly in three other systems so something may have simply gone awry. Anyway, thanks to the advice on this thread my bearing oil is changed, motor remounted, bias re-adjusted and cart wiring re-set and routed. All good!

[Firebottle]

- every 3db is a doubling of gain,

Just to correct things here for everyone's understanding; A doubling of (voltage) gain is 6dB.

3dB is a doubling when considering power, voltage x current.

[Kneesup]

Gents, By way of an update, I tried everything (short of changing arm and cart), but to no avail.... But finally cracked it on the weekend by fitting a KAB RF-1 rumble filter from Analogue Seduction. I also fitted an Isokinetic PEEK bearing housing too. Together the results are fantastic.

I couldn't imagine how putting anything - let alone something 24v active - in the signal path twixt Phono stage and Pre could possible be anything but a comprise, but no compromise is heard. The benefits are huge. What a brilliant bit of kit. Sub-sonics erased and absolutely everything vastly improved. I even had to re-adjust my azimuth setting (which the F159 stage allows you to do) to suit. The benefits are compound, if costly (the device plus more ICs).

Many thanks to all who contributed to this thread. As a result of it I have a much quieter TT and no rumble. A joy to listen to.

[Bigman80]

Glad you've sorted it.

Well done.