Exactly. I'm thinking something's not right somewhere. "High" impedance (we had much higher back in the day) is no problem for one of these amps/receivers if everything (including the headphone) is working as it should. Do a basic check before buying another amp. Start with a DC offset test...

MuZo2: Might work, at that. Let us know.

Quote: Without going back to the Yamaha drawings to check, it looks good to me. Did you find a source of magnets like that?     Quote: Looks pretty ravagey to me. Now we know it's a pleated diaphragm, so thanks for doing that. As for why HOK (and others) sometimes made drivers...

Quote: Exactly. It's the 4-pi speaker-in-a-tree effect. But I'd imagine most tweeters don't have the excursion capability to produce bass anyway. They're engineered to be tweeters and nothing else.   Quote: Uh oh. This takes us all the way back to the beginning of the thread and...

Don't forget that the HPM tweeters are piezoelectric and as such are capacitors and will read open circuit (infinite ohms DC), though not infinite impedance, which is ohms AC (audio is AC). Use a capacitance meter to test them.

Quote: That was my experience too. Surprisingly little difference with most (but not all) of the back taken out.

Whenever anyone asks a question about "enough power", I always think of the Magneplanar website's response, and I paraphrase: "How effin' loud do you want it?"    As long as you don't make the amp spend a good bit of its time in severe clipping (adding the powered sub would greatly help...

Quote: Sure. Open-back is especially risky. It means you have to get the [preferably large] diaphragm right up on the ear, or else have really really good sealing and density in your pads. An extreme case would be the oil-filled pads Koss and Sharpe used back in the day. With tight seals...

Quote: You're supposed to be the grownup and make sure it doesn't "has a spike".  Once the silistor is jumpered, you can determine if the 'phone is damaged. If not, replace the silistor.

Quote: The resistor is probably a special kind, a silistor, a type of PTC (positive temperature coefficient) thermistor. It's an overcurrent protection device. Yours may be a different kind of PTC thermistor, but the function is the same. I've often wondered if it would be possible to...

Quote: No, there's more to it than that, and you know it. Har.

I've long suggested people make their own binaural recordings for the sheer enjoyment of it and to use as a tool to  learn about headphones and what makes them good or not so good at reproducing binaural cues, which should, I've always hoped, lead on to learning what makes headphones good or...

And I'm still waiting for someone to make a powered version of a KEF Uni-Q speaker with an isodynamic tweeter, but I think I'll be waiting a long time. Besides, then you couldn't use your vintage receiver to power it, and what fun is that?

Quote: Sure. I should have added "de-symmetrize" to the list. Break up any possibility of a cavity resonance (which could create a peak or a suckout) in the audible band. It wouldn't take much.

Quote: Indeed it wouldn't, so long as it broke up the symmetry of those aluminum cups. Remember: Wherever possible, diffuse, diffract, absorb.

Quote: Sounds encouraging-- it's risky to attempt open-back, but there are other pitfalls attending vented-closed, and it sounds like you stepped around them nicely.   As for the name, I suggest hyphenating the heck out of it: CrossTex-FosFade, or even CrossTex-FosFade: The Headphone.

Quote: If EchoWars breathed on it, it may be okay. All I can tell you is that this was my amp+preamp for the latter half of the '70s and when I got my humble Hafler DH-101 preamp the difference was so dramatic it won a daytime Emmy.   The switching on the 4650's preamp is very handy, so...

Gotta love that bank of tone controls. Very nice.

Oo, what is that sleek black beauty?

Aha! So it's flat, single-sided and clamped in the center. That makes it similar to the TDS-16 driver (and no others that I'm aware of). Nearly unique.

Drakkard: very interesting to see the different TDS-15 versions and hear that someone rotated the rear magnets so they didn't reflect.   I must be one of the lucky ones with a bass-heavy TDS-5M. Is the 5M's diaphragm corrugated, as in the PMB driver it's modeled on, or is it flat and smooth...

I love that feeling.

Quote: Oo, I think I know the painkillers you mean. Now if a dentist caused this, then the Circle Of Pain is complete.

Quote: Sorry about the delay answering. Sadly, I have not heard the HE-400. The only HFM planar I've heard is the HE-5, a much older model. Compared to my modded YH-100, it had extended bass and treble. I thought it was very promising, although not what I'd call a cheapskate's dream deal...

Quote: eBay or Craigslist or yard sales, depending on how wealthy your surroundings were in 1980. I'd say $100 for a Pro 30 would be too much, but that's because I remember when they were $10. Consult with your wallet and walk away from anything painful. Patience pays dividends. Like I...