ting.mike

Wayne, I use a Blackberry, but I believe my friend uses a 3rd party program that lets him connect to the BBM network via iPhone.

B&W's society of sound perhaps may give something close to what you are looking for. I don't use it, but my friend who is a user keeps on talking about it.

Anyone compare the SRH840 to HD25-1?

I was ready with cash on hand to purchase the HD800, but when I auditioned them, I really shared the same sentiment with the last three posts above.

Ok, so I got a plain wire (Kimber 4TC speaker cable), put Sennheiser Cardas connector on one end, and plug the HD650 straight to the speaker terminals. Compared to using 1/4TRS jack (shared ground), this eliminates a LOT of noise. Only very small noise is left. Turns out most of the noise is from the pre-amp (Adcom GFP 565), while the power amp has noise, but very little (GFA 5802). I tried adding a resistor to kill the noise, and while it worked, the resistor I happen to have is too big (470 ohm), and it changed the HD650's frequency response a lot, making it bassy and veiled, so I'm getting a smaller value resistor only to kill the noise (perhaps 47 ohm). More on that later. I'm also contemplating building a passive pre amp now, since the source is a balanced source, and the power amp is a balanced power amp. I figured it's basically a box with XLR jacks in/out, and a Potentiometer, shouldn't cost that much. And I'll be able to eliminate the weakest link in the chain (preamp GFP 565) which is unbalanced. I hope someone else is also finding great results powering their HD650 from speaker amps..

Had a mini meet today with a Grado guy who doesn't like the HD650, and we both listened to the HD650 through the Adcom Power Amplifier again, and we were really impressed with: 1. Speed 2. Staging The problem was that my Adcom is quite noisy when plugged into the HD650, which is a big pity, cause otherwise the sound is just way too good. Seriously more HD650 owners should give this a try. I don't know what headphone amp can add speed to the HD650.

It wouldn't do anything to the amp's output impedance. It just "changes" the headphone impedance -- so the amp sees ~22 ohms instead of 32 ohms. If my understanding is correct.

Surprising! I would think that the tone would be similar (i.e Woody Grado tone), and the presentation different.. by tone you mean timbre, right?

Thanks, nate. I just talked on the phone with a local based headphone amplifier designer.. and he shared some insights: (retyped & paraphrased based on my understanding) 1. No problem with sharing the ground on the 1/4 TRS, as on unbalanced config they are always shared. Then I notice that Grado's adaptor also use 1/4 TRS female jack at the end. 2. The impedance matching device is useful if the speaker amplifier has limited power/current, as matching the impedance will allow the amplifier to produce more current. As I'm using a 300W mosfet, I have no use for such devices. 3. The Grado Adaptor: This is how it works (according to him) - The 2 ohm resistor is in parallel with whatever headphone you plug in. And regardless if you use a 32 ohm Grado or 300 ohm Senn, the resulting impedance will be somewhere less than 2 ohm (1.8~1.9 ohm) So, I suppose this design is not limited to only Grado headphones. - This is where the 20 ohm resistor comes -- to bring that ~2 ohm resistor back to safer levels (don't want the amp driving a 2 ohm load into headphones ) - On choosing the 20 ohm resistor, he said that Grado probably tested different values and find out what sounded best. Generally, he said, if you increase the impedance, the bass will be greater. (Hmm... add 200 ohm to the AKG 501 for bass boost?? ) Okay, hope that is all good now.

Just read this post by Zorander on HF: Ack! Is this for real? I'm doing exactly that-- using a 1/4 TRS jack and bridging the speaker taps!

Everyone keeps on comparing the HF2 to the PS1 sound, and I still haven't heard the PS1 so I can't get a picture of the HF2. I do have heard the RS2, the HP2, the GS1000i, and the MSPRO, all considered different than the regular Grado sound (RS1 sound). How would the HF2 compare to those four? If the mids are less forward than the RS1, does it mean that the HF2 is similar to the RS2?

If my physics isn't too off myself, I think you're looking at the current flow in reverse. Again from the Grado picture, the current flows from the bottom to the top, so the amp will see a 20 ohms first, then the parallel combination of 2 ohm and the headphone impedance. But I'm no expert in electronics either. As nate said: This sounds more correct. Looks like the resistors in the Grado diagram is not an impedance-matcing device rather a level attenuator device. Besides, doesn't impedance varies with frequency? so, you can't impedance match a headphone to an amp using a resistor. Yes. Smeggy said that your b22 speaker terminal and headphone jack is the same output.

Deepak: Assuming the wiring on the Sennheiser 4-pin XLR is identical to the K1000 tail adapter, I suppose it should work.

I'm gonna try to build the Grado resistor one once I can find 10 watts resistors. ASL products is hard to find here. I'm just using a cable with no resistors or impedance boxes and it works. So why is a resistor even needed? (other than for volume control maybe)

Hi. Resurrecting a one year old thread here. And this is my first post at Head-case. I actually tried this as well, and have gotten really good results. I don't use balanced cabling, so it goes: HD650 stock cable > Neutrix 1/4 Female w/ Canare starquad > Power Amplifier. The Power Amplifier is an Adcom GFA 5802 which is a 300W/channel into 8 ohms. Pre Amp is Adcom GFP 565. Source is CEC CD5300. I really like the result, especially soundstaging is phenomenal, and like catscratch, also improved speed, detail, and low-end control. The problem is there is a low noise, sort of like radio interference noise (like what you guys are also getting), and I wonder what can be done about it? Also, have anyone tried to build the Joseph Grado adaptor? I'm still trying to source the 10W resistors, but I can't discern why he designed a 2 ohm resistor connecting the hot and cold cables.