Helpful Site with lots of Phono related test, measurement and analysis

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JamesD
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#1 Helpful Site with lots of Phono related test, measurement and analysis

Post by JamesD »

Astonishing site for vinyl fans. http://korfaudio.com/

Lots of testing, measurement and analysis for setup and for diy design of turntable, tonearms and system matching. Doesn't preach to the various mantras but tests, measures and analyses how things really work... not surprisingly it reaches many of the conclusion members here have reach for system design and setup :-)
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#2 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by Nick »

Wow, lots of things to read there.
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#3 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by IslandPink »

Cor (f) !
What a great site. Just been having a look through the headshell tests - very interesting.
Then looked at the aluminium 'cap' for the DL-103 - I want one !
Nice, thanks James.
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#4 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by izzy wizzy »

Thanks James. Been doing a lot of reading. Very interesting.
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#5 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by vinylnvalves »

IslandPink wrote: Tue Jul 21, 2020 9:45 pm Cor (f) !
What a great site. Just been having a look through the headshell tests - very interesting.
Then looked at the aluminium 'cap' for the DL-103 - I want one !
Nice, thanks James.

Just get a better cartridge :!:

It’s a bit like a busman’s holiday for me...accel gauges and the like- wish I only ever had one signal to look at a time :( The cost of having equipment to do dynamic measurements at home is too deep for my pocket... Static gauges into the AD port of a BBC B computer back in the 80’s is as complex as I got.
As they say nothing new that hasn’t been around before, the flex bearings - NAD tried that unsuccessful. Separate headshells is a weakness in some of his testing but I suppose it’s the only way to do back to back experiments. The separate head shell stopped me buying a Dynavector arm a while back... would be interesting to understand what he has against that arm.

I didn’t realised someone had cloned the Rega arm, in a cheaper material. :x

It’s good to see Carbon fibre arm tubes have some merit.. as that’s what I am playing around with at the moment.. I do however have a separate smaller tube - as a tie bar up the middle.. which I am using the mission 774 as the test bed. Interestingly no mention of ceramic bearings on the blog.. I have an SME vertical bearing where I have replaced the two rolling elements with complete ceramic bearings- it rotates freely significantly longer than the steel ones they replaced, no lube either.
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#6 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by JamesD »

How are you finding the Carbon Fibre arm wand? How thick are the walls and are you using any damping?

Curious as to what better cartridge than a Denon 103 at a similar price? Curious as to your cartridge 'taste'

Do you have any insights from your accel. testing as to how to cope with the reflections, etc from the bearings and from the balance weights and stub?

ciao

James
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#7 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by vinylnvalves »

I haven’t tested the carbon wand for the Mission yet, mounting it is more challenging than building it, working from home isn’t giving me much spare time currently either, as having to put more hours in to offset the inefficiencies of remote working. I have used wrapped tube instead of pultruded tube, I don’t understand why manufacturers use pultruded tube arms, it very stiff along its length but more bendy. Higher damping is all I can think but at the expense of stiffness. I am using 8mm OD with 1mm wall, as that’s the same diameter as the mission tube, and fits beautifully as it’s just under size.

Damping, I am not using any. I will fill the tube with some chunky wool, to stop resonances. Taking a few strands of chunky knitting wool and twisting it together, pulling it taught for insertion and letting it relax and expand. ( Think Tom Fletcher showed me this) The tie bar has been shelved for the moment- as cannot see how to join composite in tension ( have posed the question to a friend/ colleague at the national composite centre)

I had a Denon 103R with a Zu shell a few years back.. came with an Orbe I bought. Replacing it with my Dynavector 17D2 was like lifting a veil- the Denon is smooth, but lacks detail, not my taste. I currently use an Ortofon Kontraplunta B I have an A and C too, but prefer the B. For the money, £380 for a Denon, Audio Technica or Hana cartridges would be where I would look. I need to buy a cartridge to fit the Mission Arm as I don’t think any of my current collection are that well matched to a light arm, so have the same dilemma as cannot justify the expense.

I only uses Accel gauges at work for verification work, I have a background in mathematics modelling...FEA. I have modelled a few different scenarios for arm tubes, how the head shell attaches and flexes if about as important as tube stiffness. When you venture into more realistic scenerios with compliance in the bearings etc, your assumptions are very hard to validate and are very influential. The only thing which is easy to show is the Cranfield idea of the damping trough at the front of the arm changes the mechanics from a cantilever to a supported beam which is good.
I did do some free size optimisation a few years back on a new piece of software to see what an arm without any preconceived constraints looked like..it looked a lot like the copperhead tonearm.

I think that having a longer arm with a damping trough will negate the issues of longer arms, and could be a good solution. So I am currently thinking I may make a damping trough to fit a 12” arm for my rock to use with the Mission arm. The challenge is the rock is designed for a 9” arm, so need to come up with some Heath Robinson arm mounting. Adding a trough to the hyperspace is even more of a task. My third option my KD550 isn’t easy to attach stuff to with its composite plinth.

So currently lots of ideas but a lack of enthusiasm to realise them.
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#8 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by simon »

That's interesting, I have a Kontra B and a 103 pro and I think they're pretty similar in detail, but the Denon has a nicer musicality and is my preference. The Kontra sounds a bit thin in comparison, not the same body and presence if that makes any sense. It was quite a long time ago when I compared them in the same arm and turntable though.
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#9 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by vinylnvalves »

Again. Like you Simon, it’s along time ago on a different turntable with a different arm. I may not have had it set up correctly as I have just read they like about 2.5 grams of tracking force. They are cheaper than I remember too, maybe I was thinking about the 103S from a cost perspective. I had an accident with my Dynavector 17D2 not long after..., the nice insurance company replaced it with a new 17 D3.. could I get along with it.... gave it a 100 hrs to see if it got better, part chopping it for the Kontra B which restored all the magic I had lost. Haven’t played with the vinyl side really until recently when coming across some of my treasures from my youth in the attic.
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#10 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by JamesD »

Mounting arms to decks that are not designed for the arms is a whole new ballgame - I spent some time considering the whole energy loop of turntable motor, drive system, turntable bearing, record to platter interface, record rotational energy driving the stylus, stylus mechanically driving the cartridge generator, cartridge headshell mechanical interface, headshell arm interface, arm wand mount and bearing interface, counterweights and stub interface to arm wand, arm wand to mount, mount to arm base, arm base to turntable plinth and plinth back to motor interface and didn't really get anywhere productive as too many variables for me to cope with as a simple physicist - probably a full FEM analysis would yield some insights but the assumptions behind it would require a lot of analysis and iteration... of course each step in the loop is subject to outside influence too so plenty of chance to 'pollute' the signal

One thing that did come out of it and that is obvious is that the turntable motor provides the energy that drives the cartridge generator - obvious but I had overlooked it until I thought through the energy loop.but it helps to explain why the rotational drive system and platter momentum and bearing are so important and why idler, belt and direct drive have there different signatures that tend to come together in the best of each type...

The damping trough like the 744 is interesting but I found with mine and a couple of different cartridges - Elite MCP555, Shure V15 type III, Denon 103 that I didn't like the effect of the damping and having applied the recommend amount and paddle kept reducing it until I had removed it all...

I have a 12" 8 mm graphite rod to try in my arm once I add a headshell - thinking of adding a wenge headshell with a compression collar fit onto the graphite rod. Again doing the unscientific thing and changing lots of things at once and hoping to make a valid comparision :oops: I'll settle for an improvement! It will be some time before I get to try this of course...

Using chunky wool makes a lot of sense given how effective that is in loading speaker cabs internal volumes to reduce the amplitude of acoustic waves - rather neat solution and it will be very interesting to hear how that works and how critical the volume of wool and the amount of twisting is - I bet it depends on the type of sheep wool as well...

Like the KD550 deck a lot - I have its bigger brother the KD990 that has a cast aluminium composite spider frame that mounts the DD motor isolated from the veneered chipboard plinth to make it look conventional - really nice automatic deck that is safe for the family to use...

My 103 is a lowly straight DL103 but I have learnt how to get the best out of it over the years - a matter of energy management at the cartridge/headshell end of the arm but it isn't the last word in detail, air and grace. I like the Dynavector too but for me the musical performance rules my judgement and the 103 does that just fine... If I had free choice a TSD-15 would be it but thats 10 to 20 times the price... I'm going to resurrect my V15 type III with a new JICO SAS stylus and wooden body too just to see where it lies against the MC cartridges... one day...

I came on this site yesterday and marvelled at the guy adding carbon fibre struts to MM stylus assemblies to triangulate the cantilever! Intriguing but I think I have too much hand shake to try this!!!
http://www.schiller-phono.de/en/room-cantilever
Google translate on the German pages works reasonably well and there is much more info there...
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#11 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by IslandPink »

Now that's commitment !
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#12 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by vinylnvalves »

I think it would be my eye sight not my hands which would be the challenge. Boron fibres would have been better :!: Shorter cantilever achieve the same result.. but would need a better motor as the movements will be smaller.

It sounds like a lot of us have too many projects on the back burner. Only Mark seems to be progressing with his horn slowly.
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#13 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by JamesD »

Boron fibres! Never thought of that but ought to as the MCP555 has a boron cantilever. Are boron fibres easy for the diyer to get? The 0.28mm carbon fibre rods are widely available. Its tempting as an AT-VM95E is inexpensive and its only the stylus assembly at risk...

I'm not brave enough to experiment with the 103 as he shows on the german language pages!!!

Way too many projects! I have a dozen power amplifier designs to build and four different riaa pres and... and...

Life is too short and in the meantime I got to finish's Phils buffer design - well finish the write up so he can build it - the designs frozen...
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#14 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by IslandPink »

I think ZYX have taken it to a logical limit of sorts, with their diamond tube cantilevers. The only high-end cartridge I liked in my system was a loaned ZYX Airy R-1000, and that was because the midrange sounded almost exactly like the 103R ; but the top end was lovely, very resolved and natural.
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#15 Re: Helpful Site with lots of Phono related test, measurement and analysis

Post by JohnG »

The individual who put me onto the Korf Audio Site, also put me onto a rebuild service for a Kontrapunkt B.

The rebuild service is the best money I have spent on a Cartridge the improvement over the standard K'b has been very noticeable.
The K'b Rebuild I have gone for is using internals from other more expensive Ortofon Cartridges, with a Ogura Beryillium Cantilever and S+Tip.

I have heard my Build used between 20 Hours and 150ish hours, as a comparison to a Rebuilt Ortofon Vienna.
It was great to hear the two side by side, and to pick up on how the K'b had settled in and delivered a very pleasing performance, when compared to a almost unobtainable cartridge .

I have additionally compared my build to a approx 300 hour usage Original Ortofon K'b on another system,
It was agreed the Original K'b is not a competitor to a rebuilt K'b, the K'b owner is keen to get the rebuild service on the one in use when it has a few more hundred hours of use on it.

On one occasion my rebuilt K'b was compared to the 200ish Hours Rebuilt Ortofon Vienna and a
Newly Completed 20ish Hours K'b rebuilt as a Vienna mimic.

All three were close Siblings, with the Vienna seemingly having the best upbringing.

If a person has had a great service from a K'b and are wondering 'what next' a rebuild using improved materials might prove to be the most prudent route to investigate for the next outlay.
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