[DrivenKeys]

Hi Everybody!

I was never the biggest fan of my dt770, so when I broke a driver, I decided to play.

The Kennerton Vali driver by Peerless has gotten a lot of attention, as it's very nice quality and only about 11 bux each. I love paper speakers, so couldn't resist.

https://www.digikey.com/products/en?keywords=HPD-50N25PR00-32‎

Driver install is very easy. Just pop the original driver out of the frame, cut down and smooth out the tabs, glue the driver to the perfectly matching 50mm surface.

I went through a lot of experiments, I can post pics if requested. Long story short: It's a pretty amazing, but kinda crazy driver, begging for lots of power, an open can and expert damping. I continue to refine the closed experience, but the highs make it tough to control.

It's so detailed and smooth, requires no hole-tuning for excellent and balanced bass, and gives the 250 ohm Beyer solid competition with a very elegant signature. However, in this can, it's near un-liveable without eq. Plugged into a phone, you'll be ok, but the bass volume and detail really suffer. Once properly powered, It's pretty incredible, but the highs present interesting challenges.

The factory graph tells most of the story, but I was surprised at how much bass I experienced. Unlike the graph, the bass curve sounds nice and flat, with deep extension. The mids are forward, detailed, and personable. Norah Jones sounds fantastic, until she hits about 2khz. Actually, the sound is still amazing, it just spikes at this point. I used uapp's parametric eq to pull 2.2k all the way down, which really helps. Unfortunately, there's only so much range in eq, sometimes not enough. The driver simply requires damping. If closed, a lot of thiking needs to go into the cup. Either closed or open, the front requires some skill.

The secret sauce is in damping only signals around 2k, with a gradual curve back up, while retaining everything else. There is so, so much to love, and most of my damping materials remove too much.

If you've never done this, start open/semi-open. This driver with this can is a more advanced proposal. After a few weeks of this beautiful unicorn chase, I'm going to try some 40mm bdnc drivers here and move these peerless to an open can. Hopefully, I'll soon discover the right front cloth, any advice is much appreciated.

 

[DrivenKeys]

Some details about my current tune:

-I just discovered these 30mm thick hybrid donuts really help the treble spike. I have the 105 mm, but the mounting ring looks like the larger sizes will fit.

https://m.aliexpress.com/item/32920435885.html?spm=a2g0n.shopcart-amp.item.32920435885&

1. The Beyer comb/felt ring combination allowed the bass, but there was muddy distortion in the mid-bass. First I tried extra felt with no effect. I replaced them with a ring cut from 1/4 inch foam found in a fabric department (I think it's made to adhere layers of fabric with ironing) The mid bass balanced out just right, and the ring's sense of depth was retained. After burn in, I tried removing the ring. The mud was mostly gone, but it still sounds a lot better with the ring, mostly in soundstage. I later added some stretched/perforated packaging paper around the ring to break up the slightly canned feeling.

2. Duck brand shelf liner. Not my idea, got it from a very popular Beyer thread. It helps refine the highs, adding some gentle bounce. I have a pad the size of the driver inside the cup and a full coverage pad in front of the driver.

3. Paper dot just over the driver's paper diaphragm, cut to the same size. I was going to use some old drawing paper, but found the pad's cover was thick and perfectly dimpled, so I used that. Layering is important, this dot's dimpled side is the first layer facing the driver. The second layer is the shelf liner.

4. The third layer is the same paper, cut to the size of the driver, perforated with a hole punch, except for the center 10mm. I basically used the idea of the solid grills over many drivers, like the mdr-v6 or takstar's 53mm. Solid center with more perforation over the surround, holes slightly overlapping the diaphragm. With the liner in between the paper layers, the sound is relaxed, detailed, and much more balanced.

5. Two full size layers of felt in the back of the cup. I tried many options; several different paper towels, 5 different types of that ironing-adhesive cloth stuff, several woven cloths in all sorts of layers and quantities. They all did something interesting, but the felt is really the only one that addressed the more offensive frequencies without removing the good ones. I'm really trying to retain the more open (for a closed can) soundstage here. Strangely enough, the felt doesn't damp the same frequencies when in front.

6. Just one or two more layers of magic cloth or paper I haven't yet tried. First in line are woven microfiber lens cloth, then microfiber terry cloth, then maybe some tp. I've spent hours stuffing full-size circles in front to learn which frequencies they block, sparing application of the lens cloth may be the ticket...

So far, with eq, these are pretty great. However, as soon as I get lost in the music and give it some juice, that 2k spike can shoot right into my skull. Please keep in mind, I'm more sensitive to highs than a lot of Beyer fans, and this happens a lot more or less depending on what's played. In this current form, I'd say these cans are both very smooth and very hot. It's an interesting, strange, fun signature. I just really need to reign in that spike.

 

[DrivenKeys]

Pics will go here, if needed.

 

[karlsonklam]

interesting experiment. I wonder if there's a fudge with hornresp to predict the low end when coupled to the ear canal -? That's a huge Vas and low fs figure for something so small and light.

Would a properly centered LCR notch filter nuke that annoying peak?

https://i.imgur.com/NKZpGAk.png

 

[DrivenKeys]

interesting experiment. I wonder if there's a fudge with hornresp to predict the low end when coupled to the ear canal -? That's a huge Vas and low fs figure for something so small and light.

Would a properly centered LCR notch filter nuke that annoying peak?

https://i.imgur.com/NKZpGAk.png

Well, that's currently way above my head, but it looks like that could help. I've never used any of the software pictured, or the principles mentioned, but look forward to learning. Are there any good reading materials you could recommend?

This combo will probably take a back seat for now, as I'm trying to focus on a can I can drive with my LG G8 while playing master files from Tidal. Unfortunately, mqa requires bit-perfect with this setup, so wavy curved cans and all their wonders will be my long-term perfection chase.

The bdnc 40mm paper drivers I have waiting have a predictable curve sightly sloping down from bass to treble, with falloff on the higher end. The curve looks like how I eq studio phones, so perhaps my paper mqa dreams will continue on. I also have some planar headphones on the way, so projects may crawl for now.

These drivers will probably go into an open can imitating Kennerton's basic design. I have a feeling the highs will be much less dangerous with a place to escape.

I believe I now understand why Vali reviews claim there is sometimes less detail; Their thick front damping cloth had to be clearly researched, and they probably were forced to compromise to avoid painful spikes. It's unfortunate, but necessary with this one. I also noticed that Kennerton places a cone behind the driver's hole, but I couldn't tell if it was plugging the hole or just dispersing waves from it.

 

[karlsonklam]

David McBean's "hornresp" is a totally free and light (<2MB) program used by hobbyist and pros alike which can model many types of loudspeaker cabinets and features a filter wizard which can model basic active highpass, lowpass and peaking filters. It also can examine some passive networks including the so called series notch filter arrangement.
http://www.hornresp.net/


FWIW here's one example using that driver's parameters for a 6dB cut at ~2KHz
https://i.imgur.com/DWcSWAO.png

It would probably be good to do some measurements and try to flatten response via
some EQ utility to confirm what needs to be (and can be) done before buying parts.

I know very little about headphones so must be partly a high art for the hobbyist to acoustic damping. I might try
that driver in a fried HE300 (is there a safer bet ??)

 

[DrivenKeys]

David McBean's "hornresp" is a totally free and light (<2MB) program used by hobbyist and pros alike which can model many types of loudspeaker cabinets and features a filter wizard which can model basic active highpass, lowpass and peaking filters. It also can examine some passive networks including the so called series notch filter arrangement.
http://www.hornresp.net/


FWIW here's one example using that driver's parameters for a 6dB cut at ~2KHz
https://i.imgur.com/DWcSWAO.png

It would probably be good to do some measurements and try to flatten response via
some EQ utility to confirm what needs to be (and can be) done before buying parts.

I know very little about headphones so must be partly a high art for the hobbyist to acoustic damping. I might try
that driver in a fried HE300 (is there a safer bet ??)

This is exactly what I was looking for. It's been over 20 years since I studied speaker design, and never studied phones. I've known these programs exist, very happy to know this is available.

I'm thinking that a dt990 style semi open might be ideal. That can vents only the motor through a port. The cup looks deeper than it needs to be; there's almost 1/4" of thick plastic back there, I wonder if the length of the port might influence that. I wanted to see if a speaker design program could help engineer the size and shape of a similar design. These principles are coming back to me, it will take time.

In this price range, I think the safest bet is the bdnc 40mm driver I mentioned. It has that safe sloped curve. 32 ohm, high sensitivity. They're 12 bux a piece at digikey. I just tried pasting the link, but something with my phone is borked atm. If you search their site, it's one of the only headphone speakers they have. If you click the link in my first post, this 40mm driver usually appears below with related products.

I haven't listened to it yet. It's pretty cool; they package it very safely in 2 plastic trays and cardboard box. The box has a circle printed on it, and the instructions tell you to cut out the hole to use as a test enclosure. So far, the coolest speaker packaging I've seen.

Most of the other driver options I know are on ebay and aliexpress. Aliexpress has a huge sale, and I'm trying very hard to resist the beryllium drivers on sale for 68 (typically 80 or 90, I forget). The headphones driver pix thread got lost in conversation over these. They have a nice flat curve, and apparently please some very discerning ears. The seller has a range of good looking drivers with safe looking curves and price ranges, with photos of each driver's test results.

www.earphonediylabs.com is a Chinese startup that carries a handful of interesting headphone and earphone drivers. Their 40mm drivers can even include 50mm adapters. Some of their stock resembles what you can find on aliexpress, I'm sure some is the same. The prices are a bit higher, but they appear to be very knowledgeable, offering to build the can of your choice from their variety of parts.

 

[IvanDrago]

The bdnc 40mm paper drivers I have waiting have a predictable curve sightly sloping down from bass to treble, with falloff on the higher end.

Are they good?
https://www.digikey.de/de/products/...BFC-D45-7-32-012-ND/9842994?itemSeq=382152309