Periodic Audio Be mod

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The Be is Periodic Audio's current flagship DD IEM and is named so after its beryllium foil diaphragm. The driver itself is actually extremely competent, having rather excellent impulse response and THD (stock measurements here) but the tuning itself was a little too much for my own personal taste. Considering that it was already a rather warm to begin with, the 10dBs of mostly-midbass emphasis was the cherry on top of the cherry pie.

The mod that I've come up with (and am still experimenting with) attempts to follow my personal target curve and is comprised of two parts: a simple reversible mod and an irreversible advanced one.

For reference, the original FR response captured on my phone app which I used for the experimentation:

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The quick and dirty

Extremely simple; first, just seal the back vent (pictured here) with whatever material you want, scotch tape in my case. Second, the nozzle requires two layers of teabag filter; I personally cut a strip out of a Twinnings bag, folded it in half, laid it over the nozzle and fitted a silicone tip over. Further details can be seen from @james444's nozzle damping section of his Blitzwolf BW-ES1 mod.

Taping the back vent should kill the bass response slightly, and the teabag filters smooths out the peaks in the treble. This simple mod already improves the clarity and overall cohesiveness of the Be's signature quite significantly. Frequency responses below:

Red: stock FR, Black: simple mod FR

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Going further

Caution: It is recommended that you have some sort of coupler+microphone measuring rig before proceeding with the following.

Now the next part is just me wanting to kill the midbass response even further. Sealing the back vents is the best one can do without permanently tampering with components, so to go beyond that we'll have to tinker with the front vents as well. The front vent is located at the bottom of the nozzle. The location is pictured below, though mine has already been taped over:

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With a sharp object (SIM card remover, pen nib etc., needle not recommended here due to size), pierce the mesh inside the front vent. Feel free to pierce all the way as the vent is perpendicular to the driver and so you won't have to worry about damaging the diaphragm (just don't push towards the driver and you'll be fine!). Once that happens, the bass will start rolling off due to excessive leakage so you'll need to control the airflow within the chamber. Tape over the front vent and prep a needle.

At this point it's mostly a matter of art because I can't predict how you yourself will perform the mod. To start off, make one pinhole at the back vent tape. Next, play around with front vent tape by poking around. The goal here is to get as little bass as possible without rolling off; I'm essentially aiming for a linear, EX1000-style bass as much as possible. Once the bass is at the desired linearity, switch the nozzle dampening from two layers of teabag filter to three layers. The reduced lower-frequency response seems to make the sound a little more shrill, so just a tad extra attenuation in the upper end is recommended in my opinion.

The final FR should be like so:

Comparison with "simple" mod

Comparison with stock
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Some additional choice comparisons with other IEMs:

Against InEar ProPhile-8

Against Etymotic ER4SR​

Final impressions

I'm not the best person to pass judgement considering that this is tuned literally to my own specifications, but IMO this is now my favourite dynamic-driver IEM. I wouldn't call it true neutral but it certainly doesn't overly emphasise any specific frequency range. The sound is slightly warm, vocals aren't biased toward either male or female, no significant complaints on my end apart from the housing the cabling of the IEM itself. Already prefer it over the Beyerdynamic Xelento and the Sennheiser IE800S based off a comparison earlier this afternoon.

Anyways don't take my word for it, I'd be willing to send this off for a tour after New Year's. Earlier for the Ozzie boys if they're interested. (Paging @jowls)

 

Haven't got a chance to mod a FD01 unfortunately. Had a listen to a stock FD01 and didn't like it at all.

Not quite ER4, closer to Prophile-8 on graphs but it's certainly a lot warmer and smoother than the two. The resolution is still pretty much the same as stock (that is to say, very very good) but the changes to the signature sort of opens everything up and reducing that smearing effect commonly associated with bass-heavy IEMs. Staging is better than almost all the IEMs I have on hand with me right now (EDC3, 18+, SK3, F9 etc.) but I don't think that's due to the mod. Definitely no timbre issues, no metallic ringing, no plastic BA crispiness.

 

Standard wide-bore tips. I recommend that, spinfits might kill too much treble.

Also, this mod also works on the entry-level Mg model:

 

How does the entry level mod sound compares to the Be?

 

Similar, if a little brighter overall. I actually prefer the tone of the modded Mg but would ultimately still reach for the Be every time.

As a cheaper alternative though, definitely a no-brainer.

 

Got a chance to borrow a BE. I don’t like the stock tuning at all but I can hear the potential.

So I just modded it similar to @La Cenric quick and dirty recommendation:
scotch tape over back vents and micro-pore tape covering about 80% of the nozzle opening.

Resulted are excellent. This a now a really good sounding dynamic driver. I still prefer the modded JVC FD01’s more exciting and dynamic presentation, as this one is a smoother presentation, but non-the-less excellent in its own right.

Great find Crin!

 

Decided to do James front vent mod as described in the link above. Now the Be modded sounds even better. Here is what I’ve finally settled on:
- completely tape off back vent
- ~80% or so nozzle coverage with micropore tape
- front vent mod with silicone strips under tips
- medium spiral dot tips
- silicone ear hooks to keep the springy cable over the ear.