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

[Kneesup]

I wonder if anyone can advise? I've had a Inspire Rega turntable for years. It's got the full Groovtracer package, lots of SRM Tech stuff, and a J7 re-wired 303 arm. External speed drive PSU and Swagman PS to that PSU. I'm using a 2m Black. It's on a dedicated and well-isolated wall shelf.

Until recently and for many years I have been alternating between a Haden Boardman 33.3 v3 valve phono stage and a SS Edwards MC3. But recently I moved house and in my new rather dreadful room my TT wasn't sounding right at all. I then acquired a Robert Airey Worx modded Jolida F159 (Black Ice Audio). Frankly, the improvement in sound repro was astonishing. A remarkable bit of kit, but I have also started suffering from marked subsonic speaker oscillations on any LP. I have tried modifying the VTF and azimuth and anti-skate and it doesn't make any difference. VTA is a cruder mod with the Rega arm but it is set on the middle shim position which is what everyone recommends. Moreover it is the position that has worked well before.

I'm told that Ortofon developed the 2M range specifically with the Rega arms in mind. They have always worked well together for me.

Is it possible that the phono-stage is just not compatible for the arm/cart combo, or is there another trick I'm missing? I have marked motor rumble, too.

I certainly l don't want to get into subsonic filters... That would be awful.

In my limited experience of swopping decent phono stages, there is often little between them, or if there is it's more a change of flavour that better or worse (which is why I kept both my other stages - I could never decide which I preferred!), by the Airey Worx F159 is a major step-up. Can these things simply be incompatible? I know it worked well in Robert's rig.

In short, what, all things considered, could be the cause? Any help greatly appreciated. I sure don't want to chop in the F159. It's absolutely wonderful.

Cheers, Richard

[Bigman80]

I wonder if anyone can advise? I've had a Inspire Rega turntable for years. It's got the full Groovtracer package, lots of SRM Tech stuff, and a J7 re-wired 303 arm. External speed drive PSU and Swagman PS to that PSU. I'm using a 2m Black. It's on a dedicated and well-isolated wall shelf.

Until recently and for many years I have been alternating between a Haden Boardman 33.3 v3 valve phono stage and a SS Edwards MC3. But recently I moved house and in my new rather dreadful room my TT wasn't sounding right at all. I then acquired a Robert Airey Worx modded Jolida F159 (Black Ice Audio). Frankly, the improvement in sound repro was astonishing. A remarkable bit of kit, but I have also started suffering from marked subsonic speaker oscillations on any LP. I have tried modifying the VTF and azimuth and anti-skate and it doesn't make any difference. VTA is a cruder mod with the Rega arm but it is set on the middle shim position which is what everyone recommends. Moreover it is the position that has worked well before.

I'm told that Ortofon developed the 2M range specifically with the Rega arms in mind. They have always worked well together for me.

Is it possible that the phono-stage is just not compatible for the arm/cart combo, or is there another trick I'm missing? I have marked motor rumble, too.

I certainly l don't want to get into subsonic filters... That would be awful.

In my limited experience of swopping decent phono stages, there is often little between them, or if there is it's more a change of flavour that better or worse (which is why I kept both my other stages - I could never decide which I preferred!), by the Airey Worx F159 is a major step-up. Can these things simply be incompatible? I know it worked well in Robert's rig.

In short, what, all things considered, could be the cause? Any help greatly appreciated. I sure don't want to chop in the F159. It's absolutely wonderful.

Cheers, RichardI don't know if this is the same thing but i just changed my preamp and noticed that the left speaker cones were moving quite noticeably, especially the bass cones. They were quite violent actually, when the cart was in the lead in groove.

I asked a friend who suggested that my bias weight may not set correctly so I checked and he was right.

Bias adjusted and everything went back to normal.

[Kneesup]

Exactly that Oliver. Thanks for flagging it. But the bias weight adjustment hasn't helped in my case.

I was wanting to move to a new Audiomods arm in any case. Although not just yet. I'd change the arm before the phono stage.

[montesquieu]

The RIAA standard eq curve does not include a subsonic filter, however many phono stages out there use the IEC version of RIAA which does have a rolloff below 20hz. My guess is that the new phono stage doesn't have this rolloff.

Clearly though there is an issue somewhere that's causing very low frequency rumble and that may be equipment related, or possibly room related, or both. Just a thought (only one of many possibilities) but by any chance have you moved from concrete floor to suspended, or some other change in the way the table is mechanically coupled to the stand/floor/room?

It could be a combination of room issues + kit problems on the tunrtable, plus the fact that subsonics were filtered on your old kit. Do you still get rumble when you use one of the old phono stages? When was the last time you oiled the bearing and changed the belt?

[Kneesup]

Thank you, Tom, for taking such a time to reply so painstakingly. The TT is on a high quality wall shelf, so no issues with the floor or table. The room generally is smaller and more 'intense' sonically, whereas my old room was airy and glorious, so there could be some interaction with speaker proximity, but it happens even at the lowest volumes. So I think probably not. The only thing that's changed kit-wise is the phono stage. Dual belts and oil are perhaps three years old. But relatively low hours. The roll-off RIAA issue certainly deserves attention. I'll ask the ever-excellent Robert Airey. Thank you again.

[Bigman80]

Exactly that Oliver. Thanks for flagging it. But the bias weight adjustment hasn't helped in my case.

I was wanting to move to a new Audiomods arm in any case. Although not just yet. I'd change the arm before the phono stage.Ah, sorry. I didn't know if it was that but it struck me due to the change in preamp. The phonostage was the same. Mad.

Anyway, hope it.

[montesquieu]

Just looking at the specs of the original Jolida, it has what it describes as a bass boost of 3db at 20hz, which is quite a lot in terms of deviation from RIAA, and could be causing or at a minimum exacerbating your problems. Not sure if the modding work would have addressed that.


Basic Specifications:
1- Gain @ 1KHZ in low gain position 40DB with 47K input.
2- Gain @ 1KHZ in high gain position 60DB with 47K input.
3- Noise floor in high gain position approx -70 DB with input load set to 10 ohms, noise floor will be lower with gain set in low position.
4- Frequency response with RIAA EQ is Plus/Minus 1/4 DB from 250 HZ to 20KHZ, + 3DB at 20 HZ (Bass Boost)
5- Distortion .05% @ 1 KHZ 1V RMS out.
6- Plate voltages APPROX 90V on input stage, 70V on second stage.
7- The calibrate meters work the same way as the XTR.
8- Rear panel adjustable loading
9- uses 2 6922/6DJ8 tubes and comes with 2 sets of tubes, one 6922 and one 6DJ8

[Kneesup]

Great detective work, Tom. That sounds well worth investigating. I’ll get on to Robert (Open Door) who did the fabulous mods. I have copious bass in my rig so will happily do without that ‘boost’ if it helps. Really appreciate your help. Thank you. R

[Kneesup]

Tom. Meant to mention that Ive old both my other stages to pay for the 159. So I can’t compare. But I will borrow another.

[walpurgis]

If subsonic record warps and ripples are being reproduced by the deck, i.e. bass cones oscillating, it suggests the arm/cartridge mass is overcoming the cantilever suspension. This happens when the arm/cart resonance is too low. It occurs if a cartridge is too compliant for the combined mass with the arm it's mounted on.

[Kneesup]

Thanks Geoff, but as per my post none of those settings are solving the problem. Much as I thought they would. Moreover, the Rega/2M mix is a very good match and has never caused me problems before. The subsonic problem happens with brand new and old LPs. So it's not the record either. I'm re-lubing my bearing next, as per Tom's menu of suggestions.

[bosa]

The Edwards MC3 has a 7Hz filter on by default (switchable) so could you switch this off to see if you can reproduce the effect?

[montesquieu]

If subsonic record warps and ripples are being reproduced by the deck, i.e. bass cones oscillating, it suggests the arm/cartridge mass is overcoming the cantilever suspension. This happens when the arm/cart resonance is too low. It occurs if a cartridge is too compliant for the combined mass with the arm it's mounted on.

In this case it's a 2m black (22um, high compliance) and Rega 303 which is (by all accounts, though figures aren't available) a low mass arm which should be well suited. The absence of figures makes it difficult to get a resonance calculation though.

@Richard do you have a test record (such as the hifi news one) with a resonance test? That might shed some light.

[Kneesup]

Good call Jonathan but I sold it. I have another loan stage coming. R

[Kneesup]

In this case it's a 2m black (22um, high compliance) and Rega 303 which is (by all accounts, though figures aren't available) a low mass arm which should be well suited. The absence of figures makes it difficult to get a resonance calculation though.

@Richard do you have a test record (such as the hifi news one) with a resonance test? That might shed some light.

I do, Tom. x2: Hi Fi News and Ultimate Analogue Test LP.

[hifi_dave]

If the original two phono stages didn't exhibit this problem, it is most likely something to do with the new one.

[Kneesup]

If the original two phono stages didn't exhibit this problem, it is most likely something to do with the new one.

Well, that’s the logic for sure. But given a house move and a change of room there are so many variables. I’m borrowing another stage so... will see.

Tom: I used both my Test LPs tonight and everything is spot on. Even cantilever resonance. But the problem persists.

I also remounted my motor today as it was making a tiny noise caused by some trapped mounting glue. And I cleaned and re-oiled the bearing assembly. Probably overdue.

I also reset and routed the wiring from my cartridge.

All these things have helped. I’m sure of it. But the subsonics persist.

So, I’ll await the test alternative phono stage. It will arrive soon.

Thanks for everyone’s kind input.

Richard

[walpurgis]

If the original two phono stages didn't exhibit this problem, it is most likely something to do with the new one.

Logic suggests to me that if the warp and ripple signal wasn't present, the phono stage wouldn't be reproducing it. I'd still be investigating the tonearm and cartridge, sticky arm bearings or an overcompliant (defective) cartridge cantilever suspension could account for the problem.

[hifi_dave]

The same turntable, arm and cartridge didn't give the problem with the previous two phono stages.

[walpurgis]

The same turntable, arm and cartridge didn't give the problem with the previous two phono stages.

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

[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.