Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: AllanMarcus on January 02, 2021, 04:53:28 PM
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Hi.
I have my mainline volume set as quiet as possible, and I'm still get some volume. I would expect the volume to be off when both knobs are all the way counter clockwise. Other than adding a preamp to get the volume lower, is there anything I can do or check?
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You could switch the input to one that isn't being used. That would give you zero volume.
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What's your source output voltage? What headphones are you using? Is the behavior of the level controls otherwise working properly? (The volume does increase when you turn up the coarse and fine controls)
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You could switch the input to one that isn't being used. That would give you zero volume.
Not a great option. I want to listen, just not as loud as with the volume all the way off.
What's your source output voltage? What headphones are you using? Is the behavior of the level controls otherwise working properly? (The volume does increase when you turn up the coarse and fine controls)
Headphones are the Utopia.
Not sure about voltage. I go USB from PC to Bifrost. Specs say "Maximum output: 2.0V RMS"
Otherwise the attenuators work properly.
Of course I can just lower the volume on the PC, but I prefer to just adjust on the amp. At any rate, does it seem right that at the lowest volume on the amp, there should still be decent volume in the headphones? any ideas? Anything I can measure?
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You could add a pair of attenuators at the input of your Mainline to attenuate the DAC level a bit.
https://www.parts-express.com/Harrison-Labs-12-dB-RCA-Line-Level-Attenuator-Pair-266-244?gclid=Cj0KCQiAx9mABhD0ARIsAEfpavS1aL266cSgvYpJ-Dy2ZphIzMoti6TSObUgXlvdz-LQe5RBwYHD7lAaAjTVEALw_wcB (https://www.parts-express.com/Harrison-Labs-12-dB-RCA-Line-Level-Attenuator-Pair-266-244?gclid=Cj0KCQiAx9mABhD0ARIsAEfpavS1aL266cSgvYpJ-Dy2ZphIzMoti6TSObUgXlvdz-LQe5RBwYHD7lAaAjTVEALw_wcB)
The Utopias do look to be quite sensitive, so a little source attenuation isn't unreasonable.
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I'd rather not add the attenuators; one more thing in the change - meh.
I tried my HD6xx (Sennheiser HD650), and same thing. I can just lower the volume from the computer to make it lower (I prefer to use the Amps volume, but I will live), but I was surprised by how loud it is with the volume all the way down on the Mainline.
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And you're 100% certain that both the coarse and the fine switches are all the way down and that they both adjust the volume when you use them? I suppose it's worth mentioning the obvious that both switches on 0dB is not all the way down.
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What? 0db is nothing! how can it get softer then nothing! :-)
Yes, -45db on the course and -7.5 on the fine. Both make it louder when I turn them clockwise.
Might there be a problem with my amp?
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And going to low impedance will also drop the level down?
I don't currently have either headphone here to double check the settings, but I do know that an HD-800 has to be turned up reasonably far.
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Not sure if this has been solved, but happened to drop in today and have the Mainline and Utopia here right now. The volume is very low when using minimum volume and low impedance mode, but still loud enough to be quite listenable. I'm using the 2.5V output from the Chord Hugo TT2
For reference, my comfortable listening levels (which are normally around 82dB) are at about -20dB with this setup (Coarse: -27db, Fine: -7.5dB). I tend to prefer the Utopias in high output impedance mode, but that doesn't make a huge difference to the perceivable volume (and I haven't taken the time to measure)