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Rothwell Rialto Phono Stage - the info

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Rothwell Rialto Phono Stage - the info

Postby DeepEnd » 25 May 2018 18:32

Following on from my post in the Rega section on my "mad moment" (viewtopic.php?f=32&t=104391) my new phono stage has been left powered up (unused for two weeks) so finally got round to getting the leads out of the back of the A3.2 and into the phono stage (connected with the free "River" connects that came with this purchase that are usually a £65 option) for a few hours of serious listening. So as promised here is my initial thoughts/observations.

The unit is supplied in a small box along with a "wall wart" complete with various adaptors to suit different countries.

Rialto-0521.jpg


Rialto-0522.jpg


The unit is made from a surprisingly thick gauge of steel with what appears to be a tough paint finish and a heavily engraved thick aluminium front panel. I got to check this as the first thing I had to do was open it up to change from the default MC setting over to the MM setting for my system.

Rialto-0530.jpg


I think the choice of materials might be governed by their experience of guitar pedal units - you could probably stand on the phono stage without damaging it. As you can see this is a discrete dual channel unit with the larger capacitors, transistors and MC/MM switches on the top surface with SMD components on the underside.

It's not the most stylish of units and I would suggest putting it out of the way as it has the brightest blue LED I have ever seen - it makes the ones on my A3.2 look puny - something I would have previously suggested was impossible as they alone light up the whole room at night.

Phono-0555.jpg


Phono-0554.jpg



The Rothwell River interconnects are worthy of mention due to their low capacitance. Rothwell advise "Very high quality interconnects with silver plated copper conductors and FEP insulation. Very low capacitance of only 64pF per meter, with braided screen giving a high degree of shielding.

So how does it sound? More to follow:-
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Re: Rothwell Rialto Phono Stage - the info

Postby Coffee Phil » 25 May 2018 21:02

Hi DeepEnd,

It is not a bad looking unit, other that needing welding glasses to look at it.

You can trace out the LED ballast resistor and bump up the value until it matches the other lights in your system.

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Re: Rothwell Rialto Phono Stage - the info

Postby DeepEnd » 25 May 2018 21:41

Sound quality then - well this is where it gets difficult and I am not sure if I have the vocabulary to fully explain:-

Yes it has a full, yet controlled bass register, yes it has an extended yet sweet upper register, yes it has a clear midrange, yes it has a good transient response and dynamics, yes it has a wide, deep and high soundstage, yes it has PRaT (sorry but I do hate that term), yes it's quiet but then again so does the phono stage in my Musical Fidelity A3.2 Integrated amp. It has proven just how good the phono stage in the A3.2 really is and you have to spend a lot to better it.

Is the Rialto better than the A3.2 internal stage? - undoubtedly "yes". My initial reaction was slightly subdued as it does not "push" any aspect at you.

The best way I can describe its performance is that it just seems to "disappear" as do the speakers and you end up just listening to the music with individual parts flowing into primary focus when the artist/engineers wants and then seamlessly flowing back into the mix (but you can still follow each musical strand easily with incredible low level detail) in a way the A3.2 could not manage and adds a very small amount of sparkle and air that gives better clues on the acoustics of the location (or the amount of reverb added by the engineer). It's growing on me with every listen and has me digging through record just to try it, highly addictive.

Did a quick white noise plot before moving leads and then after through the Rialto for comparison. The slightly falling response I thought was my cartridge may well be the A3.2. It would appear the Rialto has a flatter, wider bandwidth (also both show some digital artefacts from the encoding process).

WhiteN11BPA3.jpg
Rega Planar 3, Nagaoka MP-11 Boron retipped with Paratrace via MF A3.2


WhiteN11BPRR.jpg
Rega Planar 3, Nagaoka MP-11 Boron retipped with Paratrace via Rothwell Rialto


I repeated a track from my recent stylus evaluation so on the following link file QJANC11MP64.wav is a 96/24 bit via the A3.2 phono stage and QJANCBPRR75.wav via the Rialto both with the Paratraced MP-11 Boron.

https://www.dropbox.com/sh/xemqhttgutp8 ... oLIta?dl=0
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Re: Rothwell Rialto Phono Stage - the info

Postby billshurv » 26 May 2018 00:33

What test disk did you use? Not many have actually white noise on. The pink noise tracks are fairly ropey as well.

At least you can work out the compliance of the cartridge now. That does show why I really don't think the RB300 is suitable for most MM cartridges. But that's just me :).

Looking at the bottom of the audio band there is considerable difference at 20Hz. Guessing the rothwell has some sort of rumble filter (you never get the same result playing the same record twice, but that is a very significant difference). At the top end the differences will be due to loading and if we had a calibrated run off the test record you could work out the cause. What would be interesting would be to eq the two to be the same on rips and see if the differences were still there (i.e. is is all down to the cart loading).

Interesting data, thank you.
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Re: Rothwell Rialto Phono Stage - the info

Postby DeepEnd » 26 May 2018 14:50

In answer to the questions test record used was Hi-Fi Sound - Stereo test Record (HFS81). The white noise is band-limited to 40 - 15,000kHz cut at -15db (ref 1kHz @ 5cm/sec rms).

For information the Rothwell does not have a rumble filter. If it did I would have expected the resonant peak to be at a much lower level than on the graph as this would have been filtered out. It has been independently tested at +/- 0.1db from 10Hz all the way up to 100kHz with a 3db point below 4Hz!!

Having looked back I think the A3.2 version was with the original 100g counter weight and the later Rialto one with the heavier 120g counter weight and the peaks between resonance and 40Hz may have something to do with this rather than the phono stages.

With regard to loading the Rialto is 47kOhms with 150pF and MF have never let on what the input capacitive loading of the A3.2 phono stage is.

If you look at the following pink noise test there are sufficient oddities for me to decide there is something going on other than arm resonances (lid? plinth? wall bracket?) for me not to make any real conclusions.

PinkN11BP100A3.jpg
MP11-B(P) via A3.2 with 100g tungsten counter weight


PinkN11BP120A3.jpg
MP11-B(P) via A3.2 with 120g tungsten counter weight


PinkN11BP120RR.jpg
MP11-B(P) via Rialto with 120g tungsten counter weight
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Re: Rothwell Rialto Phono Stage - the info

Postby billshurv » 27 May 2018 02:30

Interesting. The first two plots show what I would expect from a higher mass counterweight as it actually reduces effective mass by being closer to the pivot.

Mk1 eyeball without drawing lines suggests that the A3.2 output is more 'pink' that the Rialto. This is not what one might expect from the white noise tracks. Interesting. There is significant HF deviation between the two due to loading differences, but couldn't immediately tell you which one was closer to correct.
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Re: Rothwell Rialto Phono Stage - the info

Postby billshurv » 28 May 2018 03:27

Meant to ask are both the white and pink noise tracks RIAA pre-emphasised? sometimes they are, sometimes they aren't on test disks.
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Re: Rothwell Rialto Phono Stage - the info

Postby DeepEnd » 29 May 2018 10:18

Sorry for the delay in responding but I have been away from the PC for a few days but the Pink and White noise track are recorded "with" RIAA pre-emphasis on this test record. I have also drawn some 3db per octave lines on two of the Pink Noise traces shown before.

PinkN11BP100A3.jpg
Nagaoka MP11 Boron/Paratrace, 100g counterweight via MF A3.2 phono stage


PinkN11BP120RR.jpg
Nagaoka MP11 Boron/Paratrace, 120g counterweight via Rothwell Rialto phono stage


These seem to confirm the results of the white noise tests with the A3.2 being somewhat down at the 10kHz point compared to the Rialto. This might explain the improvement in air and sparkle between the two but not the "disappearing" effect the Rialto has.

I have also noticed that in the Nagaoka "Better Sound for Ever" brochures, held on the forum database, that a number of their cartridges do show a 1dB-2db dip between 3KHz and 10kHz in their frequency responses that shows up on the Rialto white noise response.
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Re: Rothwell Rialto Phono Stage - the info

Postby billshurv » 29 May 2018 11:30

I'll take another look when I get some time. Neither look great above 10kHz, but that could be the test record. Interestingly around 8-10kHz area changes in FR can have an effect on perceived image height, so differences here could be significant.
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Re: Rothwell Rialto Phono Stage - the info

Postby DeepEnd » 29 May 2018 14:25

Just had a bit of shock. I was digging through my collection and found I had another test record (Hi-Fi for Pleasure TEST123) that also had a pink noise track (no white though) so thought I would just do a quick test even though the sleeve/notes are a bit lacking on the technical info compared to the HFS81 I used initially. It just says "filtered pink noise" for this track and the tracking level tests don't give any info in either db level or um levels used.

However the MP-11 Boron/Paratrace via the Rialto gave this:-

T12311BPRR.jpg


It would appear the test tracks I used for the initial graphs are appalling inaccurate :oops: :cry:
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Re: Rothwell Rialto Phono Stage - the info

Postby billshurv » 29 May 2018 14:51

I did warn you! :)

That is more like I would have expected.
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