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Will
8470
Chief Product Officer
Oct 29, 2015
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hiduplawak
17
Oct 29, 2015
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WillAwesome, but the optimal gain setting to pair with the odac rev B is 3.3x. Would it be possible to have this option?
RailTracer
1
Oct 29, 2015
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WillGlad to hear that! This is my first drop and I was waiting for this option before jumping on it.
Budget_Audiophile
98
Oct 29, 2015
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WillHi Will, would it be possible to do a separate drop for short interconnect cables for stacked DAC/amp?
bilditup1
80
Oct 29, 2015
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hiduplawakThis is a difference in gain of ~0.5dB. I don't think it would be a big deal.
hiduplawak
17
Oct 29, 2015
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bilditup1At 3.5x, this amp will clip when paired with the odac rev b from the other drop.
Will
8470
Chief Product Officer
Oct 30, 2015
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hiduplawakHey hiduplawak, shoot me a link? Appreciate you looking into this.
hiduplawak
17
Oct 30, 2015
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WillHey Will, the O2 has a maximum output of 7V, anything higher will cause clipping. 3.5x was ok with the odac rev A as the Vout was 2.0vrms, the rev B however has a Vout of 2.1vrms. This is why JDS switched from 3.5x to 3.3x post revB.
"Revision B’s stronger output voltage of 2.10VRMS must also be accompanied by a slight DAC volume or gain adjustment when used in O2+ODAC; optimal gain is now 1.0/3.33x." -http://blog.jdslabs.com/?p=1003
This is also documented in Nwavguy's blog, "The Math – For those who want the exact numbers, or want to change the default gain settings, on AC power the Maximum Gain = 7 / Vin(max) and on (low) batteries it’s 4.5 / Vin(max). So if you have a 2 volt CD player, the max gain is 7/2 = 3.5X on AC power. If you have a 0.5 volt LOD portable it’s 4.5/.5 = 9X running on the batteries." - http://nwavguy.blogspot.my/2011/08/o2-details.html#maximuminput
This is also documented in Nwavguy's blog, "The Math – For those who want the exact numbers, or want to change the default gain settings, on AC power the Maximum Gain = 7 / Vin(max) and on (low) batteries it’s 4.5 / Vin(max). So if you have a 2 volt CD player, the max gain is 7/2 = 3.5X on AC power. If you have a 0.5 volt LOD portable it’s 4.5/.5 = 9X running on the batteries." - http://nwavguy.blogspot.my/2011/08/o2-details.html#maximuminput
hiduplawak
17
Oct 30, 2015
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WillFor those wondering how loud will the amp will drive their headphones, there is a excel spreadsheet on HeadFi to calculate this.
http://www.head-fi.org/a/headphone-power-calculator-spreadsheet
Just plug in the impedance and sensitivity (watch out for mW or V) and the amp Vrms rating (input Vrms x gain setting), it'll spit out your resulting headphone "loudness" in dB(SPL).
For example, when using the odac rev B with the amp at x1 gain with a dt880 600ohm,
600ohms, 96dB/mW, 2.1Vrms x1
will result in 104.66 dBSPL which is plenty for home listening.
Will
8470
Chief Product Officer
Oct 31, 2015
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hiduplawakDiscussed this with our manufacturing partner and it's an easy switch. Appreciate your help!
hiduplawak
17
Oct 31, 2015
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WillAwesome, thanks for taking your time to work things out with your manufacturing partner. I'm glad to be of assistance.
Waddle
48
Oct 31, 2015
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hiduplawakI'm confused still, I got the Headphone Calculator app and plugged in the K7XX values (62 Ohms, 105 dB/V) for a target loudness of 95 dB SPL (I won't be listening anywhere near this volume). How do a distinguish which O2 gain configuration I should be getting?
NooBKaNoN
20
Nov 2, 2015
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Willjust to clarify the medium edition is now going to be 1x and 3.3x gain?
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Thanks for supporting this drop! Just received confirmation from our manufacturing partner that we’ll be able to offer a choice between two different gain options.
The standard gain configuration (what everyone has selected by default) is 2.5x (low) and 6.0x (high).
The new option allows you to select a gain configuration with 1.0x gain (low) and 3.3x gain (high).
Right now, everyone in this drop has the standard (2.5x, 6.0x) selected. To change your option, head over to your transaction page (https://www.massdrop.com/transactions) and make the change.
We would have liked to offer more options, but introducing any additional variations at this stage could cause meaningful delays (we’ve confirmed offering one additional gain configuration will not impact fulfillment time).
Thanks for your interest, support, and help making this drop possible!
Reply to this post with your questions.
Edit: Switched the gain configuration to be 1.0x and 3.3x rather than 1.0x and 3.5x.