# VST 2 vs 3 refractometer?/



## jlarkin (Apr 26, 2015)

Hello, I saw the SCAE have the version 2 refractometer for £550 a whopping £100 saving on the 3 (from what I've been able to see). I was wondering if anybody has tried both to comment on the differences ? The VST site mentions a few but they don't seem to be quantified do it's hard to see how significant the difference is.


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## jeebsy (May 5, 2013)

The 3 is available on Has Bean for £650? Differences do look fairly incremental, @garydyke1 might be a good man to answer


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## DoubleShot (Apr 23, 2014)

Listed as fourth generation:

http://www.hasbean.co.uk/collections/vst/products/vst-lab-iii


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## The Systemic Kid (Nov 23, 2012)

Specifications for VST III on left and VST II on right









Marginal degree of improvement in tolerance accuracy for VST III. Based on this, picking up a discounted VST II would be a canny buy if the discount was decent.


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## garydyke1 (Mar 9, 2011)

Main improvement other than accuracy is battery life , some folk have quoted double.

You should find the reading settles quicker than before. You know, when you press for a reading 6 times and its always slightly different ? That should have gone.


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## The Systemic Kid (Nov 23, 2012)

garydyke1 said:


> Main improvement other than accuracy is battery life , some folk have quoted double.
> 
> You should find the reading settles quicker than before. You know, when you press for a reading 6 times and its always slightly different ? That should have gone.


Thought the variance in readings was due to temp of sample settling down to VST temp.


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## garydyke1 (Mar 9, 2011)

I had noticed readings creeping both up and down randomly with previous version. New one settles quicker and remains settled


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## jeebsy (May 5, 2013)

So it would tell me it's too cold to work more quickly?


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## The Systemic Kid (Nov 23, 2012)

You need the polar VST version, jeebsy.


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## goodq (Oct 10, 2011)

Thought this was a good read http://socraticcoffee.com/2015/05/measuring-total-dissolved-solids-a-refractometer-comparison-part-ii/


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## Mrboots2u (May 10, 2013)

goodq said:


> Thought this was a good read http://socraticcoffee.com/2015/05/measuring-total-dissolved-solids-a-refractometer-comparison-part-ii/


Its still a flawed comparison


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## MWJB (Feb 28, 2012)

goodq said:


> Thought this was a good read http://socraticcoffee.com/2015/05/measuring-total-dissolved-solids-a-refractometer-comparison-part-ii/


There's no datum (dehydration results, reference solutions) for the samples tested. Because of this, there is no way of determining "precision", the way the data is presented suggests that an instrument that typically reads in a higher/lower range than the others could be the outlier, this is not so, it's more the variance for each unit that is what we are looking at. Also because there is no datum for the samples, we don't know whether the variance observed relates to the coffee samples, or the instruments themselves...if the VST II was indeed exhibiting such a perceived variance in precision this should have been addressed with the reseller or manufacturer. Even then, they still had the VST III & Atago to test, why include the 3rd instrument if there were doubts regarding performance re. warranted spec.? Why aren't they testing even numbers of units?

It's odd how the VST II showed the greatest variance in 2 tests (received its samples last in all 3 tests), then was comparable to the VST III in the last test. Relative mean readings between the VST II and Atago reverses back & forth over the published tests.

Initially Socratic did not publish the specs for the Atago, which is odd because they are normally supplied with the instrument & differ from the website published figures (I had to point Socratic to these), what is also not mentioned is that whilst the VST comes with a higher, warranted spec (to NIST traceable standards), the Atago does not come certified as conforming to specs supplied - if you wanted the Atago certified to NIST standards, to be sure that it conforms to the lower specification quoted on the official website (+/-0.15%TDS, +/-0.10%BRIX, +/- 1.0 deg C), you'd have to pay extra.

If the Atago typically performs to this standard, or better, why are they not certified/warranted out of the box, why aren't the specs reflective of this?

This chart shows the discrepancy in published & supplied accuracy (there is no precision spec for the Atago) for a 1.35%TDS brew at 20%EY:

*Points 1&2 are the typical accuracy range of the VST II +/-0.03%TDS*

*
Points 5&6 are what +/-0.15%TDS looks like...you could have a mid box brew but still be clear outside the target area, even this is not what you get without an upcharge for certification.*

I often find that my preference is +/-1% Extraction Yield for a given method & grinder (typical stated accuracy is around half of this for the VST at common brewed ratios), not being confident that I can even translate a reading to +/-2%EY or more, would make me think twice about spending hundreds of pounds on an instrument & that's even before temp variance (compounds the accuracy error for the Atago at +/-1C) & EY calculation is discussed.








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## Xpenno (Nov 12, 2012)

The linked article doesn't seem to mention if they are pressing the button on the VST 2 multiple times (which I find is a requirement of using it). It seems to average the results over a few readings before it settles down. It's my understanding that the Atago has this functionality built in to a single press and potentially by the sound of it so does the VST 3. Could be a key difference or I could have just missed it when reading the article


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## MWJB (Feb 28, 2012)

Xpenno said:


> The linked article doesn't seem to mention if they are pressing the button on the VST 2 multiple times (which I find is a requirement of using it). It seems to average the results over a few readings before it settles down. It's my understanding that the Atago has this functionality built in to a single press and potentially by the sound of it so does the VST 3. Could be a key difference or I could have just missed it when reading the article


The linked article used 30 samples, 10 different samples from each of 3 brews, those 10 samples were divided between the 3 instruments. They did not take 10 readings (button pushes) from a single, verified, sample. This introduces noise from inconsistency of samples as the brew stratifies & evaporates, it's not in accordance with the VST sampling protocol. Any button press is the average of multiple readings, I rarely see the reading change by more than 0.01%TDS for brewed with adequate cooling of the sample.


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## jeebsy (May 5, 2013)

I'd like to try leaving it for 60 secs then pushing the button once, but then the unit/sample is usually below operating temp. Maybe now summer is coming...


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## goodq (Oct 10, 2011)

Personally since whatever I use the refractometer for is really "guidance" and nothing I am doing would really get compromised over a maximum delta of 0.05% TDS. So the difference or "improvement" from VST 2 to the 3 doesn't really matter (to me).

What I really like thought is that FIANLLY VST are not the only show and there is very good competition, albeit the software is not great from Atago (yet!).

What that link really says is not the difference between VST 2 and 3, rather it says how amazing the atago is for less than 1/3 the price.


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## MWJB (Feb 28, 2012)

goodq said:


> Personally since whatever I use the refractometer for is really "guidance" and nothing I am doing would really get compromised over a maximum delta of 0.05% TDS. So the difference or "improvement" from VST 2 to the 3 doesn't really matter (to me).
> 
> What I really like thought is that FIANLLY VST are not the only show and there is very good competition, albeit the software is not great from Atago (yet!).
> 
> What that link really says is not the difference between VST 2 and 3, rather it says how amazing the atago is for less than 1/3 the price.


I think you meant to write, "how amazing *an* Atago is...", there are no prices given in the article, nor receipts showing what was paid for any of the 3 instruments tested, so you don't know what the Atago cost relative to the others, nor the level of certification it was sold with.


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## goodq (Oct 10, 2011)

MWJB said:


> I think you meant to write, "how amazing *an* Atago is...", there are no prices given in the article, nor receipts showing what was paid for any of the 3 instruments tested, so you don't know what the Atago cost relative to the others, nor the level of certification it was sold with.


I saw a few on ebay before around the 300USD mark. A bit of searching I found a few more.

http://www.ebay.co.uk/itm/EMS-ATAGO-Pocket-Coffee-Cafe-Densitometer-PAL-COFFEE-TDS-22-From-Japan-New-/111592177958

http://www.ebay.co.uk/itm/New-ATAGO-Pocket-Coffee-Cafe-Densitometer-PAL-COFFEE-BX-TDS-Japan-Import-/251900369663?_trksid=p2141725.m3641.l6368

http://www.equipment-search.com/equip-detail/analytical-instruments/ATAGO-PAL-COFFEEBXTDS-Brix-0-25-Pocket-Coffee_281706421990.html

Comparing that to the £650.00 price tag from hasbean and how close it is to the VST 3 its a bargain


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## MWJB (Feb 28, 2012)

A "bargain" might be considered something of equal specification, but at a low price, like a £1200 spec. espresso machine for £400, whilst a £400 specification machine is a cheaper machine...& it might be just what you want, but it's not typically going to be comparable on spec., as with any product.

None of the links state that NIST certification is included in price.


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## goodq (Oct 10, 2011)

That is a good point. Makes me wonder why there isn't a certificate of quality to ensure calibration.

Still liking that there is more players which ultimately would hopefully reduce the price of those devices


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## jlarkin (Apr 26, 2015)

Hi all, thanks for replies and info. I have one on the way now (I couldn't resist any longer) went for the V3 from hasbean. As I think quite a few people who commented here have the refractometer already was wondering, do you have any top tips or remember and newbie mistakes to avoids etc?


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## Mrboots2u (May 10, 2013)

Tip - Follow the vst protocols each time to endure accurate use snd reading. ....


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## MWJB (Feb 28, 2012)

Weigh & keep a note of any vessels you are brewing into (my Chemex weighs 586.5g for instance) so that you can know the brewed beverage weight. Or use 2 sets of scales with drip, one weighing the brew water added, the other just the beverage produced.

Be sure to give brews a stir (top to bottom, not just round & round) before taking samples, give the samples adequate time to cool (at least a minute) in a clean cup/glass & also to equalize on the prism (30s).

Fresh pipettes for transferring samples.


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## goodq (Oct 10, 2011)

Here is a good link. Matt Perger on coffee refracting.






In the video he uses the syringe filter for brewed coffee which I don't think you need unless your testing espresso.


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## MWJB (Feb 28, 2012)

goodq said:


> Here is a good link. Matt Perger on coffee refracting.


You need the syringe filters for any metal filtered, unfiltered, or paper filtered brews with very fine/espresso type grinds. Most people wouldn't bother for paper filtered drip with medium/coarse grinds.


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## goodq (Oct 10, 2011)

I use them all the time since I test primarily espresso. They are expensive though. Have you tried something else that is cheaper ?

I tried these before

http://www.amazon.co.uk/iiMash-Diameter-0-22um-Disposable-Syringe/dp/B00OT0RSDO

They give the same reading as the VST filters but you really need some muscle to push the coffee through. Also I had a few break from how much I pushed


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## Mrboots2u (May 10, 2013)

goodq said:


> I use them all the time since I test primarily espresso. They are expensive though. Have you tried something else that is cheaper ?
> 
> I tried these before
> 
> ...


Currently unavailable .....

What price were they ?


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## goodq (Oct 10, 2011)

Mrboots2u said:


> Currently unavailable .....
> 
> What price were they ?


£4.54 for a pack of 10. So its £1.20 per filter for the VST filters and £0.452 per filter for those filters. Numbers wise the same but they are a pain to deal with.


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