Odd low frequency dip, and a way to address it... any comments?


Senior Member
Aug 13, 2017
Somewhere Northeast of Kansas City Missouri
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PrimaLuna Dialogue Premium TubePre (2 channel+sub)
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McIntosh MC152 SS Amp (2 channel)
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Yamaha RX-A850 Pro (the other 5 channels lol)
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MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX build, Audirvana+, LiquidSonics, SoX
Chord Electronics Ltd. Qutest
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Sony UBP-X700 /M Ultra HD 4K HDR
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Martin Logan ElectroMotion ESL
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Martin Logan Motion C2
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Martin Logan Motion 4
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Martin Logan Motion 4 (yes, another set of these)
Martin Logan Dynamo 700
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Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
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PrimaLuna & Lumin iApp
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ThrowRug, SaddleBlankets, WideBand & BaseTraps...
It seems to me that the method in the link to above, https://community.roonlabs.com/t/cr...-new-room-eq-wizard-rew-with-inversion/208776, addresses Phase correction at step 24 in the detailed document referenced in the video and provided in the comment section of that video... There is also a video that the author, Serkan Gur, has posted a tutorial that explains how to do Phase correction with the free tool called rePhase, found at rePhase.org, also one of the tools suggested on the MiniDSP website... While it is true that most hobbyists tend focus on the amplitude/SPL side of room correction, there is plenty of information available for those that tend to dive deeper into the subject...
Last edited:

Anatoliy Gavrilov

Apr 27, 2019
Main Amp
SE - 6С33С - 6П15П
Additional Amp
Technics SE-M100
Universal / Blu-ray / CD Player
Sony CDP-557 ESD
Front Speakers
Seas 3-way
I am confused by phase issues; I was considering trying to use the MiniDSP 2x4 HD's 2048 tap to create a single FIR filter exclusively to address a phase issue but don't know if this is possible, and how to go about designing the proper filter (examples seem to focus on magnitude not phase).
I do not use DSP - in my room the frequency response is within + - 3 dB. But once I experimented with an active 1/3 octave equalizer to equalize the frequency response of a 3-way speaker system.
At 1 meter it is very easy to align the frequency response, and from it the phase curve is aligned:





But when the microphone was placed on the listening point (2.5 meters), then all the equalizer settings spoiled the measurement graphs, and the usual passive filter of this 3-way speaker showed an uneven frequency response of + - 2.5 dB.

Put the microphone at the listening point and align it with the frequency response processor, paying special attention to the 400 - 4000 Hz range - it should be as even as possible. Pay less attention to phase distortion of low frequencies, since group delay at frequencies below 200-300 Hz is not so sharply perceived by our hearing against the background of mid frequencies.
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