Dalla Corte Mini - Second Look - Page 19

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Carneiro

#181: Post by Carneiro »

Marshall wrote: Negatives:

- Muddy shots. They are very much the same from one blend to another, and it is very difficult to experience distinctive flavors. This may be an issue with the narrow, deep basket or the pressure control. I'm only guessing. It's the main reason I've decided to buy a GS/3 Paddle.
- Overpressure valve placement. It renders the volumetric dosing useless, as it measures the water flow before it reaches the OPV and gets diverted. It may also not be as effective as some other valves.
- Preinfusion. Essentially useless without line pressure. DC may have a preinfusion mod in the works.
Hi, Marshall!

Have you compared DC x GS/3 side by side? I wonder if the basket is the problem about the muddy shots, as LM double baskets, although are 58mm, have most of it's volume on a narrower diameter (I measured 55mm, and as far as I remember, the area of the screen are almost the same between them). Ok, the dispersion screen is wider and if one doses 17-18g, the shape of the puck is unique (wider at top). Is the puck of DC that deeper than LM's double puck? But, I'm just wondering...

How about the single shots on DC?

About the OPV and flow meter, I really remember the OPV right after the pump... I don't remember if the flow meter is before pump - that could work if the return of the OPV goes to pump after the flow meter (I know some people have changed this diverting the water back to tank).

There is a Super Mini available here in Brazil (a close friend bought the Mini that the guy was selling too), for a reasonable price (it's expensive but the price is an opportunity, considering the crappy prosumer market here), but I wonder about the 54mm group design! :mrgreen: I like playing around with my Gaggia and LM or other 58mm baskets... :twisted: Of course the Super Mini is kind of an overkill for me, but this obsession is taking me over!

Márcio.

Kleefisch

#182: Post by Kleefisch »

Hi Jim,

while you decided not to issue a full review of the DC Mini, it would be interesting to know in what band of the 'Exceptional Espresso Rating' the DC Mini roughly would have landed.

Maybe you can tell or guess?

Best wishes
Kleefisch

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another_jim (original poster)
Team HB

#183: Post by another_jim (original poster) »

None of the reviewers was able to get familiar enough with the machine to complete the review.

For me, neither changing the dose, nor the temperature dial, nor the pressure, gave me reliable flavor profiling. You can get great shots with the right coffee, but their range was limited and did not include my usual fruited SOs.

I believe, but could not confirm, that the OPV is imprecise, and that the temperature control has a larger deadband than the $5 button stats on home machines. Since the group is a proprietary size, we didn't have the instrumentation to confirm this. But whether I'm right or wrong, this is a $3K double boiler machine, and shouldn't be using the 1970s vintage electro-mechanical on/off thermostat, instead of the pulsing PID used on the same groups in the commercial models.
Jim Schulman

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JmanEspresso

#184: Post by JmanEspresso »

Amen.

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Carneiro

#185: Post by Carneiro »

I have to agree that the DC temp controller is weird. But I've tested the Mini with a Scace Device, and got some like that: at regular use, with a pause between shots, you get something 2°C lower than the dial temp. The machines doesn't seem to overheat after a long period without flushing (yes, a little bit wide deadband of the controller). The intra-shot temp is pretty stable (over 30 seconds).

But, if you flush a small amount of water, the cold water seems to trigger the temperature controller, as the thermocouple is near the water inlet at the top part of the boiler. I've managed to get Scace temperature higher than the dial (1°C above).

Sorry but I don't have data or graphs to show you... I had only 2 sessions with the machine and the Scace device.

I think it has a flawed design. Even if you put a PID to read the TC and control the heat element, I think you will get similar results.

As I said, the TC is measuring the water temp at the top of the boiler, so the group is always a little bit cooler. At the same time, if you try some small flushes (cold water at the TC), it overshoots the temperature, but the group reaches the right temp (similar to dial). If you keep doing this, you get higher temp than the set point.

I think a PID controller with the probe placed near or at (inside?) the group could do a great job, considering the size of the boiler. This friend that has the DC Mini doesn't like to think about modding it, though...

About the OPV, I've tested the group pressure with a gauge and needle valve and got around 9 bar simulating a double shot. Maybe some Super Mini owners could tell us how the machine behaves with a rotary pump.

One thing I wonder about the DC is the dispersion disc and screen... I got a lot of center depressed pucks... But maybe is the barista! :mrgreen: I've used a Baratza Vario.

Márcio.

Kleefisch

#186: Post by Kleefisch »

Hm... That sounds as if the DC Mini would not be a first class machine :shock:

I ordered one a week ago, so in a couple of days I will get a hands-on experience anyway.
Hopefully the DC Mini was a good choice as a replacement of a Vibiemme Domobar Super HX!

These are my thoughts:

I agree that a PID would be nice for this machine, especially at the given price point. Common sense of whatever I read before was, that the sheer mass of the brew group compensates for any temperature variation the thermostat might induce. Márcio's Scace data seems to tell another story. That said, it should be possible to overcome this slight variation by a standard flushing technique, if necessary. Pretty awkward, for sure.

Considering the pressure related issues you mentioned, AFAIK they made some changes in the parts of the vibration pump, OPV and flowmeter in the current model. It might be (and I hope so) that these changes do some good and were not present in the model that has been evaluated here in the past.

I will be back and tell about my own experience when the machine was in my 'lab'!

Best wishes
Kleefisch

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Carneiro

#187: Post by Carneiro »

I agree that a PID would be nice for this machine, especially at the given price point. Common sense of whatever I read before was, that the sheer mass of the brew group compensates for any temperature variation the thermostat might induce. Márcio's Scace data seems to tell another story. That said, it should be possible to overcome this slight variation by a standard flushing technique, if necessary. Pretty awkward, for sure.
Well, the mass of the brew group compensates any variation, but it gives you, in general, 2°C lower then the dial (you should test more than I did... :mrgreen: )... That story about small flushes and the higher temperature is not a real world situation - but for sure is flaw design.

Please, keep us updated about the internals of your new machine!

Márcio.

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HB
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#188: Post by HB »

Split follow-on discussion to Owner experience with Dalla Corte Mini.
Dan Kehn