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A low-budget parametric headphone EQ setup using old iPhone

MachOne

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Hi folks. I've been reading here for a few years and have learned a lot, I thought I'd share a cheap but effective headphone EQ setup that I've just started playing with. This is obviously targeted at people who need to EQ external sources, and can be used on loudspeaker systems also, not just headphones.

It uses an iOS app called AUM, which is a host for AUv3 instruments and plugins. But it has built in effects, one of which is a parametric EQ plugin. AUM can host 10 plugins per chain, which gives you 10 EQ slots if you just use a single chain, but if you send the output of the chain to a mix bus, then use that mix bus as the input to the next chain, you can have quite a few EQ slots running at once. I don't think you'd run out of slots for typical applications, or DSP headroom on even an old iPhone 5. EQ profiles can be saved and recalled, and there are other parametric EQ plugins that can be purchased you prefer to be able to see the curve.

The setup below cost me around $25USD. The interface was an eBay bargain, and the iPhone 7 was given away as it has a faulty audio IC, which is not an issue when running an external interface. Any USB class compliant interface will work. One potential downside is battery swelling due to holding the charge at 100% with some heat from the processor. (side note, the IU2 footprint is pretty much identical to that of the ATOM+ amp, which makes for a neat stack)

20211103_113038.jpg
 

Head_Unit

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The picture won't load despite repeated attempts, don't know if its the host or me. So I'm unclear what the chain is-what is the music source? And the EQ is actually happening in the iPhone, or that is just the controller?
 
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MachOne

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pk500

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Cool setup but definitely not great as a portable rig.

Wouldn't it be easier to just run Equalizer APO and Peace interface off a Windows laptop or something like EQMac off a MacBook? What am I missing here?
 
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MachOne

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Cool setup but definitely not great as a portable rig.

Wouldn't it be easier to just run Equalizer APO and Peace interface off a Windows laptop or something like EQMac off a MacBook? What am I missing here?
It's definitely not intended to be a portable rig. This was just an example of using some very inexpensive parts that were laying around to create a very compact and powerful EQ setup that could be hidden behind a mixer/amp etc for EQing external sources. You could achieve the same thing in many ways, but most would be either much larger or more expensive, or less flexible in the software. As well as being able to use the built in AUM EQ, it can run plugins like TB Morphit. I'm not sure EQ APO would be easier to use - AUM on IOS is pretty straightforward to get going.
 

pk500

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It's definitely not intended to be a portable rig. This was just an example of using some very inexpensive parts that were laying around to create a very compact and powerful EQ setup that could be hidden behind a mixer/amp etc for EQing external sources. You could achieve the same thing in many ways, but most would be either much larger or more expensive, or less flexible in the software. As well as being able to use the built in AUM EQ, it can run plugins like TB Morphit. I'm not sure EQ APO would be easier to use - AUM on IOS is pretty straightforward to get going.
Got it. Cool. Thanks for the explanation!
 

Head_Unit

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google drive link to the image
OMG I absolutely never thought about using gdrive as an image host. Any down sides? Or...can you actually use it as an image host?
 
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MachOne

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OMG I absolutely never thought about using gdrive as an image host. Any down sides? Or...can you actually use it as an image host?
You can't use it to host forum inline display images, only to share to people with the link.
 

Merkurio

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Nice effort, but the Qudelix-5K is a better hardware solution with just a USB-C to Lightning cable (in case you don’t like to use it via BT).
 
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MachOne

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Nice effort, but the Qudelix-5K is a better hardware solution with just a USB-C to Lightning cable (in case you don’t like to use it via BT).
It looks great but it's significantly more expensive. The aim here was to use very inexpensive, almost obsolete parts to make a very powerful EQ setup that could EQ external sources. As a bonus, it's not limited to 10 bands of EQ.
 

Dundy

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It looks great but it's significantly more expensive. The aim here was to use very inexpensive, almost obsolete parts to make a very powerful EQ setup that could EQ external sources. As a bonus, it's not limited to 10 bands of EQ.
Hi! so I can listening Tidal, then instal AUM with good plug-in and then throw my dac -> amp -> headphones?! I’m iPad only user and I’m sad there no parametric eq for stream Music like  Music, Tidal etc.
 

DWPress

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Hook it up to a Motu Ultralite MK5 for 8+ channels, a reverb AU plugin for running convolution filters instead of/in addition to the PEQ and this could be a Rp4 killer for multichannel use. Add your favorite streaming app or Roon/jRiver controller, done.

I just might play with this. Thanks for this gem of piecing it all together.
 
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MachOne

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Hi! so I can listening Tidal, then instal AUM with good plug-in and then throw my dac -> amp -> headphones?! I’m iPad only user and I’m sad there no parametric eq for stream Music like  Music, Tidal etc.
This was put together to EQ external sources rather than iOS streaming apps. As far as I know it is not possible to get Tidal app sound into AUM, and there doesn't appear to be a system wide parametric EQ for iOS unless you are using a jailbroken device.
 

DWPress

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No way to loopback to iPhone, maybe connection not 2 way USB in AUM?

Check out iConvolver ($6.99 in appstore) for a FIR convolution ON the iPhone which I've been told will work but I haven't tested it myself.\

Regardless, even if its external sources only it is a nice solution.
 
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MachOne

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No way to loopback to iPhone, maybe connection not 2 way USB in AUM?

Check out iConvolver ($6.99 in appstore) for a FIR convolution ON the iPhone which I've been told will work but I haven't tested it myself.\

Regardless, even if its external sources only it is a nice solution.
You can sort of do it with multiroute audio using the headphone out and USB out at the same time, using Audiobus and AUM together, but it's not stable enough to be practical in my experience. AUM doesn't do multiroute audio, but AB does, and AB IO slots will show up in AUM. It might work ok with just AUM with a multichannel interface though.
 
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