[tortugaranger]

Hi All,

1st round of product pics for the ePot.V3 Max Stepped Attenuator & Preamp Controller are in.

Product Page: https://tortugaaudio.com/products/diy-preamp-components/electronic-stepped-attenuator-epot-v3-max/

Cheers,
Morten

[glynnw]

I believe you said that the mini lacked the calibration feature.  Mine goes weird about once a year and recalibration always sets it right again. What does one do when a mini goes wonky?

[audiobasic2000]

Good Afternoon, glynnw:

From the Tortuga mini ePot v3 web page...

'About LDR impedance and calibration

Due to its small size, the Mini is not capable of calibrating its own LDR attenuation module. Therefore is you need an LDR attenuation module with a difference impedance level or to replace a bad module you will need to purchase LDR modules from Tortuga Audio. Alternatively, if you also own an ePot.V3 Max you can use any Max to recalibrate any LDR module at whatever impedance level you wish. If you send in your existing V3 LDR attenuation module, we will recalibrate your module for you for a  $5 fee plus return shipping.

For more general information, please refer to this link to read more about LDRs, their impedance and their calibration.'

Hope tortugaranger (Morton) doesn't mind my quoting a subsection of the web page.

glynnw, were you a beta tester or something? My understanding is that the min ePot v3 has only been recently introduced and in production-wise. Reason is I have one on the way and if what you indicate about the drift would cause one to be concerned if they do not have the requisite Max but can opt to send it back to have it re-calibrated. 

Thanks.

Sincerely,
Kingsley.

[glynnw]

Thanks Kingsley - Not a beta tester.  I recently had my Tortuga balance go south and easily corrected it by recalibrating.  I have a preamp kit coming from DIYaudiostore and if I like it I am thinking of replacing it's volume control with a Tortuga unit, which are the best I have ever heard.  Looking at the mini it looks like an easy way to do it, but was just wondering about what the larger unit might offer me that the mini doesn't and the calibration issue came to mind.  So I asked.  Will not know what I plan to do until I build the kit and see what kind of space I may have around the volume control.  The mini seems like such as perfect solution in this case.  Since I also plan on ordering one of your passive kits when it becomes avaiable,I can use it to recalibrate the mini.  Sweet!
Thanks again.

[audiobasic2000]

You're welcome, glynnw. By the way, I think you meant to order one of Tortuga Audio's passive kits? (I certainly don't sell any - LOL.)

[tortugaranger]

I believe you said that the mini lacked the calibration feature.  Mine goes weird about once a year and recalibration always sets it right again. What does one do when a mini goes wonky?

What Kingsley said. 
And to my ears the V3 model is our best ever sonically. Hope you give it try and let us know your impressions.


Cheers,
Morten

[tortugaranger]

Hi All,

I quick update on the roll out of the ePot.V3 Mini and Max.

We began shipping Mini's around the last week of August while still working on finishing up a couple of loose ends with the Max. We received feedback from a couple of customers (who loved the sound quality BTW) that the Mini would freeze while turning the encoder. So we got all over that issue and after extensive diagnostics traced the freeze problem to the power supply.

Throughout months of development, we never heavily manipulated the encoder beyond verifying that it worked at all. The rest of the time we used the remote. Turns out active use of the encoder was causing voltage transients on the 3.3V bus powering the microcontroller. And while the microcontroller tolerated this almost all the time, sometimes it didn't and decided to just quit running. I was sure it was a software problem up until the moment it became clear it was a power supply problem. We'd never had a similar problem with earlier models so we weren't looking closely at this during development.

The issue was easily resolved by beefing up the 3.3V system with a larger cap which mitigated the transients. No more freezing up.

Those of you who already have a Mini have been contacted (or will be shortly) and we'll be swapping out your Mini for a new one with the fix in place. We'll retrofit the returns once we have them back in our shop.

We held up sending out any Max units until this issue was resolved but are shipping them now since the same issue applies to the Max but somewhat surprisingly the Max was less susceptible to freezing; probably because the chip is much bigger physically and thus has more inherent power capacitance internally.

Otherwise the Mini and Max are working great and initial feedback on the Mini has been very positive.

Cheers,
Morten

[tortugaranger]

With over 6 months of production and customer feedback on the ePot.V3 MAX we are making a few changes to the MAX as part of a Rev B design that will be released soon. It was time to order more boards anyway so this is as good time to make any planned changes. A pic of the Rev B layout is shown below. We still need to go through at least one round of prototyping but after that we should be able to go straight to production.

The heart of the ePot.V3 design remains unchanged. The interfaces remain unchanged as does the general layout and the physical dimensions. The only change that is also relevant to the MINI is #1 below. Changes to the Rev B board includes the following:

1) A simpler and more robust power board (located under the main board) - not visible here

2) We've replaced the analog input switches with LDR switches similar to the V25 design except they are soldered in and not plug-ins. We never had a failed switching LDR in any of our V25 boards so I'm confident that these soldered in LDR switches will be long lived. The analog switches worked ok but could sometimes be a bit finicky so we reverted to using LDRs for input switching which worked great in the V25. The primary LDR attenuator board remains plug-in replaceable as before.

3) We substituted a DPDT relay for isolating and muting the output signals. We could have done this with LDRs as well but decided a relay would best ensure quick and definitive disconnect/muting of the output signals in case of power loss thus avoiding any artifacts, pops or bumps from uncontrolled removal of control power.

4) We eliminated the 4 isolation switches from the input and output sense signals running to the LDR calibration op amps. There was no real necessity for fully isolating these signals from the op amp inputs. Of course we retained switches on the calibration power source itself. We should have done this a long time ago even on the V25 but old habits are hard to break.

5) The final change was the elimination of the Mono switch. The inclusion of the Mono switch in earlier versions including the V25 offered limited value while significantly complicating matters especially with a pair of boards in a balanced configuration. I take comfort in its elimination knowing that there's now no possible way for any left-right channel leakage. Sometimes less is simply better. Make it so!

[tortugaranger]

The final iteration on the V3 Rev B board.

Decided to go with relays for the LDR calibration circuit disconnect. Thankfully we have miniature relays that we were able to fit in. Also modified the muting relay such that during normal operation there are NO relays actively connected to any audio signal during normal operation, only during muting and/or calibration otherwise LDRs only in the signal path.

Every iteration we've made going back 10 years now has raised the sonic bar a notch higher and to my ears the V3 Rev B is no exception. Listening to the last prototype was a delight. What I noted was better sound stage coherency and a bit more holographic stereo imaging.

Should have Rev B production boards in about 10 days.

[kernelbob]

Also modified the muting relay such that during normal operation there are NO relays actively connected to any audio signal during normal operation, only during muting and/or calibration otherwise LDRs only in the signal path.

"NO relays actively connected to any audio signal..."   Music to my ears.  Pun intended.

[tortugaranger]

I'm happy to report that as of today (4.30.21) we've completed the design update of the ePot.V3 Max to the Rev B model and are now producing Rev B boards.

The Rev B incorporates numerous minor improvements and changes that have been driven by customer feedback and our experience using the Rev A model over the past 6 months. After several prototype iterations we now have fully functional and tested production release Rev B Max hardware. The Rev B V3 Max is without a doubt the most evolved and great sounding electronic stepped attenuator and preamp controller we've designed and built to date. I expect that the V3 Max Rev B to remain our flagship preamp attenuator/controller for years to come.

As we've posted in other threads, all preamp builds going forward will incorporate the Rev B V3 Max.

We'll have updated product pics within a week or so.

More info on the V3 Max Rev B can be found here:  https://tortugaaudio.com/products/diy-preamp-components/electronic-stepped-attenuator-epot-v3-max/

Cheers, 
Morten

[craig sawyers]

Quick question. In a balanced system (so two controller boards and two plug in attenuator modules), are two OLED modules also needed?

Cheers

Craig

[tortugaranger]

Quick question. In a balanced system (so two controller boards and two plug in attenuator modules), are two OLED modules also needed?

Cheers

Craig

No. Only a single display is required. The display connects to the primary board which controls the secondary board via a 2 wire serial data link. The user only interacts with the primary board.

Also, a point of clarification in that the primary board must be designated as the right channel and connected to accordingly. Conversely the secondary board handles the left channel.

[tortugaranger]

The ePot.V3 Max is now available for balanced audio applications. We've added online documentation that discusses the details of how to wire up a pair of Max boards for balanced audio attenuation.

This information can be found in the following link: https://tortugaaudio.com/docs/epot-v3-balanced-audio-wiring/

Here's a main wiring diagram...