[neobop]

Ever notice on low power devices the bass kind of drops out?  Maybe not with EQ and enough juice, but here's another solution.  The HTF 600 has bass in abundance.  It's also easy to mod so you can tune it exactly to your taste.  Here's where I found out about these $30 wonders:
http://www.head-fi.org/products/panasonic-rp-htf600-s-step-monitor

http://www.head-fi.org/t/571005/the-panasonic-rp-htf600-s-headphones-more-fun-than-the-hd650

Oops, gotta go to work.  Later I'll post some pics.

[neobop]

The HTF600 has a little too much bass (for me) in stock form.  It's not one of those phones that's all bass and distant mids and high end. It's got some sparkle up top and the midrange is pretty good except for some glare. Like most others it takes 30 to 50 hrs break in. This is a fairly efficient phone, 100 dB/mW and 56 ohms, 50mm dynamic drivers.  The drivers are angled. They stick out in the front of the cup.  This is a vented enclosure with the 4 vents in an elongated oval on the side of the cup, opposite the driver.

I didn't hear the upper bass bloat messing with the mids that I read about at Head Fi.  There was too much deep bass and the mids were messed up by the empty enclosure.  I think they were designed for low powered devices and once you put them on a receiver or HP amp, this becomes obvious.  Still, a lot of can for less than $30, delivered.
http://www.amazon.com/gp/product/B004MMEI8W/ref=s9_simh_gw_p23_d0_g23_i4?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-3&pf_rd_r=1KFD42SQNWXW5NBX85WT&pf_rd_t=101&pf_rd_p=470938811&pf_rd_i=507846


To open the cup you pry up the baffle with a small screwdriver. There's a space between the edge of the baffle and the shiny silver band below it. This space is where the pads hook on. After removing the pads you'll see the top of two clips on one side. There are two more on the other side hidden under the foam.


First I covered all but the bottom vent with clay.  There are 11 holes up top. I covered the top 3 with clay.



Use clay around the driver to help out the plastic baffle.


I use AcoustaStuff (dacron) loosely inside to help with reflections in the cups.


After listening to the modded cans - verdict is overdamped. Removed the clay from the little side vents on the oval and the and the three holes up top. [There are a total of 11 of those holes.]  Then I reduces the amount of stuffing till it barely covered the cup.


Wow these things are amazing. Numbskull likes them too. BTW, those are stock pads.

[Noseyears]

I think they will replace my RX700's which died a few months ago, at a similar price point a no brainer.

have you tried the beyer pads?

[neobop]

Hi Noseyears,
No, I haven't tried the Beyer pads. They're said to attenuate midbass hump slightly and make the treble a little edgier but more detailed.  I'll probably get them.  I did try the rolled up paper towel under the pads and it seems to be subtle.  I think it adds a little depth. 

I might have been a little hasty with the review. They might not have been broken in all the way. I've removed all the clay blocking the vents and the bass sounds very good. Most of the irregularities are gone. It doesn't seem to go quite as deep as my slot loaded T50, but close.  I now have only a little AcoustaStuff inside and the clay on the baffle. 

I have found that they actually fit me a little better if I reverse sides and put the right side on my left.  This is because the headband is at approx a 30 degree angle relative to the cup.  Others don't seem to have a problem with this. It must be because I'm a Conehead, but for best treble I wear them with the headband almost at the top of my forehead. I'm thinking of replacing the cable and reversing the channels. The thin cable annoys me anyway. I guess I could just cut the cable and reverse the two hot leads.  It's probably a coax cable with two center conductors (PIA). I haven't decided.  I use phones mostly for movies and some late night music.  Although less efficient, the T50 is more comfortable for me and I love the sound of those ortho drivers. The HTF600 is an incredible bargain. I need a more efficient pr for the PC and my DVD DAC. The Panasonic is really quite good and keeps getting better. The other night I saw the movie Hanna with The Crystal Method soundtrack. The HTF600 sounded like they cost 5x the price.

[jonbee]

I bought a pair for $30 and did a few simple mods. I damped the baffle as noted above and put a little accordion folded paper towel in the cups for some rear absorption. I taped over the little vents on the sides of the earpieces, where the "left" and "right" labels are.
They are very nice sounding- bass is still a little fat, the highs are somewhat rolled off, and they are certainly not the last word in transparency, but they are smooth and very engaging musically, with no nasty show stoppers or distracting colorations, more so than any I've had under $200 retail. The soundstage is surprisingly convincing - while lacking in incisiveness, the presentation  is smooth and uniform. Very surprising for the price. I prefer them to Grado 325s!
I have Senn HD600s, which are much more incisive, wide range and focused, and better across the board, but I'm in no hurry to take the Pannies off to switch back. The pannies simply sound good, and are far more efficient than the Senns, so they work well with low power devices. I'm using them at work running off my PC's cheap speaker's amp, and they sound quite acceptable at any reasonable volume.
I compared them directly to the Sennheiser HD-280 PRO, which sell for $100 on Amazon. The Senns have more energy on top, and accordingly sound more upfront and present, but at a price. The upper end is harder and hashier and in the end harder to listen to. The rolled top end on the pannies serves the music better, and I definitely preferred the Pannies for general listening.
The plastic covering on the earpads is a bit sticky. I think the Beyer velour pads would be a good investment (almost doubles the cost  ). A little playing around suggests the velour pads might help with the bass hump too.

But the bottom line- they are fun, musically enjoyable and easy to listen to. If you like an easy, natural sound and don't mind a little extra warmth, you should buy them if you're looking for some cheap thrills! They are perfect for office use- cheap, and moderately isolating, so you can hear most of what's going on around you.
The construction is good for the price, but I have my doubts that they will hold up under rough use, given the price. If you don't knock them around, though, I think they should hold up well.
Rejoice! Good sound for $30!!! I've never heard the like.

[neobop]

Thanks for your post Jonbee, very informative.  I'll have to try sealing the side vents.

I ordered the Beyer pads, probably get them next week.

I tried reversing the phones again to see how they fit with L/R reversed.  They seemed to sound a little strange that way.  At first I thought it was L/R, then I remembered the angled drivers 
Soundstage to the rear and L/R reversed, Yikes - inside out.  LOL
When I first got them they seemed a little tight, uncomfortable.  The headband is easy to bend and has lots of extra room to adjust for large heads.  After adjusting a couple of times they're more comfortable and I don't need to wear them as far forward. Not bad, and the new pads should help.

[neobop]

I was just looking on that Head Fi thread for more modding tips.  I didn't come up with anything, but here's a comparison to the HD 650 (bottom of page).

http://www.head-fi.org/t/571005/the-panasonic-rp-htf600-s-headphones-more-fun-than-the-hd650/255

[neobop]

I like the velour pads. They seem to do exactly what they say, an increase in treble definition.  It's not gigantic, but worthwhile IMO.  The Beyer pads fit on the baffle very tight. It's a bit of a struggle getting them on. They're actually a hair thinner than stock pads and I was hoping to put some extra foam underneath.  They're more comfortable than stock anyway.

After readjusting the overall fit, I realized that 11 vents on the outside of the outer cup, under the headband attachment, had to be partially unblocked.  I'll take a pic and show you what I mean.  BTW, I tried sealing the side vents in the oval pattern. I like it better with them open and a little stuffing inside. The bass is much better for me. You can tune it by varying the amount of stuffing.

[neobop]

Here's those 11 vents:








When the cups are in the upright position (wearing them), the headband connectors could completely block them off depending on how they fit.  Initially, I thought it wouldn't make any difference. They're outside of the inner cup (see pics above).  It looked like pressure relief.  Now I think it might make a difference. Top to bottom coherence seems better when they're not blocked.  These sound better than ever.  I'm still amazed, and for $30.   

[neobop]

It's been awhile since this thread was up.  I thought some might be interested in this.  I have some other phones and the HT600 were just sitting on the shelf.  With "decent" 50mm angled drivers I always thought the enclosure was holding them back.  So.....







Baffle reduction surgery performed with a B&D Dremmel type tool.  Side build up with epoxy putty.   Mesh grill is purloined Panasonic boom box sourced - seemed fitting.

Seems to be improved in all areas.  Bass is more natural, less boomy and they still dig down deep enough for movies.  Not the most comfy cans I've worn, but what the hey. 
neo