Eros 2 Measurements

Maxhawk · 2048

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Offline Maxhawk

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on: July 28, 2019, 02:07:41 PM
Thought you guys might be interested in some measurements I took of the Eros 2. This is with the provided 6J32P (EF86) and 6H23P (6922) tubes. The only mod is substitution of a 0.68uF Jantzen Silver Z-Cap in place of the provided 1.5uF output coupling caps. Measurements are from a Audio Precision SYS2722.

https://imgur.com/a/DQlQ2RW

Rob Cheng


Offline Paul Birkeland

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Reply #1 on: July 28, 2019, 05:16:18 PM
Very nice!  I wish I could justify spending the dough for an AP.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline grufti

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Reply #2 on: August 01, 2019, 05:18:13 PM
Wow, spectacular! I built the Eros 1 when it first came out and it measured nearly as well once I found the source of the hum in my build. Even then, it was not as quiet and there was more 3rd in the harmonic spectrum. I bought the Eros 2 kit a while back. I just finished the BeePre and the Eros 2 is next. This has me really excited.



Offline grufti

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Reply #3 on: August 02, 2019, 10:46:56 AM
Rob, you've made a few more minor changes to the wiring layout and then one more visible change. There is a single black wire in the area between "20 and D" going in the direction of "22" in the photo of the finished circuit in the build guide. That one isn't there in your build. Most likely instead you have a shielded twisted pair running further left from "20" to roughly the location of the positive side of the C2C capacitor on the C4S board. I'd be interested to find out what you did there.



Offline Paul Birkeland

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Reply #4 on: August 02, 2019, 04:30:49 PM
If that copper buss bar is not enameled, I would go over it and plate it with solder before too long.  Raw copper like that will oxidize if it isn't plated (like the plated buss wire we provide in the kit), and it becomes difficult to solder to later if you want to make changes.  The oxidation is also unsightly.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Maxhawk

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Reply #5 on: August 04, 2019, 07:36:34 AM
Rob, you've made a few more minor changes to the wiring layout and then one more visible change. There is a single black wire in the area between "20 and D" going in the direction of "22" in the photo of the finished circuit in the build guide. That one isn't there in your build. Most likely instead you have a shielded twisted pair running further left from "20" to roughly the location of the positive side of the C2C capacitor on the C4S board. I'd be interested to find out what you did there.

I think you're looking for the ground wire that connects to 26L? See following photo. I decided to use a thicker 20ga wire left over from the Crack kit since it was a long ground. I don't think the thicker gauge does much in that position, but I figured it wouldn't hurt. In retrospect I'd use the supplied black wire next time.

https://i.imgur.com/Rx59RRzh.png


Rob Cheng


Offline Maxhawk

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Reply #6 on: August 04, 2019, 07:38:01 AM
If that copper buss bar is not enameled, I would go over it and plate it with solder before too long.  Raw copper like that will oxidize if it isn't plated (like the plated buss wire we provide in the kit), and it becomes difficult to solder to later if you want to make changes.  The oxidation is also unsightly.

Good call! I'll go back and tin it with solder.

Rob Cheng


Offline grufti

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Reply #7 on: August 05, 2019, 06:38:43 AM
Rob, thank you for checking that out. I tried to figure it out in your photo, but your imgur link leads to: "Zoinks! You've taken a wrong turn."