dsavitsk

For cheap and good sound with Grados, I think you'd be hard pressed to beat a simple MOSFET follower. Even with top quality parts it will be cheaper and dare I say better sounding, than any of the Millett Hybrids. http://www.ecp.cc/SZ.html

The RS-1s are a good option since you won't need any gain to power them from your DAC, just a buffer. Here is some detail on what they need. Why don't you just build something? A couple of back to back source followers into a 150:600 transformer will sound great, and should match the character of the DAC pretty well.

Just for the record, these are not topologically similar to the DNA, nor to each other. The DNA is a standard transformer coupled single ended design. The Wheatfield is a cathode follower that is cap coupled on the output. The Decware has a single ended driver stage and a push-pull output cap coupled to an impedance matching transformer. I've no doubt that the DNA sounds better than either of those based on just a peek at the schematics.

I think that's too bad. All someone will need is a sine wave and a multimeter to uncover this great secret, and it would be easier if you just said what you used. I guess the issue is that, unless you have tremendous core and copper losses, the numbers just don't seem to add up. But, maybe I'm missing something -- wouldn't be the first time I know you are a speaker designer, so the emphasis on matching to the speaker is reasonable. Maybe you are on to something. But, matching the load to the tube also matters, and with what little we know, this seems to not be optimal here.

I'm not much of an OTL guy, so I really know very little about how to optimize a circuit. But, I guess you can keep paralleling tubes and keep adding feedback and whatnot to get the Zout sufficiently low. As for transformer coupling, there are probably practical limits as to the load that can be presented as too high of an impedance leads to high frequency issues. But again, you can keep paralleling tubes to lower the Z out or use very low rp tubes. You might need very high mu tubes to get sufficient voltage gain to overcome the impedance ration, which means using the super high Gm stuff like the 7788 or 437a, or a driver. Also, an autoformer can change that a little as the winding is not as capacitive. As an example, the L'espressivo uses a 71a which has a plate resistance of a little under 2K. On the lowest setting (which is actually plenty loud in most cases) the impedance ratio is 1:16000 which results in an impedance of about 1/8th of an ohm. If you used a 300B it would be less than half of that. One might use a similar design but with a fixed autotransformer, a standard pot and a driver tube to drive higher Z phones, or to get the same damping with higher output. The particular autoformers I used are limited in voltage handling due to their small size, so you'd need a bigger core.

The 120 is supposed to be 6db, the 28 less. An 8:1 is an impedance ratio of 64:1. This gets you a Z out in about the right range but a voltage gain that is a bit high. The problem here is that with an 8:1, the reflected load from low Z phones is too low for the tube -- you'll get more power but you'll also get higher distortion. For the 120, a 4:1 is about right, but again, the load on the tube is too low. My guess would be that the changing sound with different Z settings has more to do with the load the tube is seeing than the interaction of impedance and phones. Maybe the distortion is all 2nd harmonic, and maybe the designer likes this. Or, maybe I am totally wrong that damping factor matters and I have been barking up the wrong tree for years. But, when someone shows up and says that, notwithstanding that fact that in nearly every case nearly everybody thinks lower Zout means better sound (with the exception noted above), that he thinks the opposite is true, I think there is reason to be skeptical. This is easy enough to test, or course, with an opamp and some resistors. I'd also like to see some distortion numbers from his amp with various loads.

My primary concern is 32 ohm Grados which sound best with a large damping factor. But, be that as it may, I am not sure your numbers add up here. With an rp of about 1500 and a mu of 20, what possible transformer ratio gets you less than 6db of gain and a Zout of 28? As for the overall design, I've built that amp (down to the JJ cap, the cerafine bypasses, the Edcor OPTs and the 5AR4 -- I think I used 6N6p's instead of the 6H30 ... basically the same tube) and it is fine, but there is plenty of room for easy improvement. I wouldn't take much from this one data point. Sounds more like a transformer with a too-low primary inductance for the load. ASL is not known for their parts quality, and it is doubtful that they invested in high quality OPTs for this.

You don't get a lot for $1200 these days. It is the single feed version of the now apparently discontinued parafeed Hagtech headphone amp (which I seem to recall sold for $1200 ... or rather, didn't sell for $1200), with a more rudimentary power supply. It's as basic as can be. I am all in favor of supporting local small shops, but they've got to try a little harder. There are a bunch of things that could be done with this circuit to improve it for only marginally more money. Also, either this is only meant for high impedance phones, or the load on the tube is awfully low.

There is some argument that DHT's have lower distortion than IDHT's. However, a small signal DHT preamp requires considerably more work and attention to detail than does an IDHT preamp, so it may be that were an IDHT preamp built with the same attention to detail, it would sound just as good. Also, people building with DHTs tend to go all out on parts, so again, perhaps building an IDHT preamp with the same attention to parts would sound just as good. Additionally, there is some contention that the big open sound people seem to like from DHTs is actually just a microphonic artifact from the filament resulting in a sort of reverb effect. Thus, the sound may be a sort of effect added to the signal. My own DHT headphone amp sounds pretty good to me -- certainly better than most other amps I've built. But, I can't say that this isn't because of the attention to detail, the parts, or the microphonics. On the other hand, it could be the tube.

I'd add outside of New Glarus, WI. Beautiful rolling hills, near enough to Madison for college town stuff and some city perks, near enough Chicago for actual city perks, lots of local organic farms, excellent beer, and cost of living is low.

I'm not really unhapppy. Had I spent another $100 I might be. The highs are not too bad, but there is a mid bass emphasis. The analogy was to suggest that there is a sort of flatness to them -- they seem to lack a little life. They are getting better with some break in, however, and at times sound quite good. I should also say that as closed phones, I was not expecting them to sound as good as the Grados. Maybe the better analogy is that the Grados are to Oris horns what the ATs are to B&W 803's. I really need some noise blocking in both directions (I share office space and don't want to annoy others, and don't want to listen to them either), so they are doing that part way better than the Grados could. However, based only on sound quality, for about the same price I think my wife's SR325's sound quite a bit better and I would be disappointed with these as my main phones. Maybe I just like the Grado sound. One other thought has occured to me which is that I always felt like the RS-1s were a little over priced (and I should say, I got mine during the Headroom/TTVJ spat when they were on a big sale). Now, I have not heard other phones that I like nearly as much (though comparisons do not go much beyond HD600's) but they did seem expensive for what they are. I think these AT's may have given me a new perspective on that; the Grados are actually a decent value in comparison.

I'm no wood worker and have only used a few different types, but for finish, I sand with up to 600 grit and then use 6 to 12 layers of good quality oil. For everything I have tried this on, walnut, padauk, maple, mahogany, it leaves the wood smooth and pleasant to touch, but still feeling like wood. I can't stand the plastic coats people use.

These showed up -- they appear to be real: real wood, well made, etc. I plugged them in and let them run for a little while, so their character may change a bit. Here's my first impression: is to what is to Oh, and they smell awful. I had to put all the packaging in a closet as the odor of industrial solvents is nauseating.

I got them from here: BuyDig.com, The Internet's Digital Superstore which was the best deal I could find (~$225). They seem legit, though the phones no longer appear on their site -- maybe I got the last pair? Their website is identical to BeachCamera.com (other than the name of course) although they cost something like $3 less at BuyDig and interestingly, Beach Camera also does not have these in stock now while they did last night. They sent me a FedEx tracking number, so I should have them by Friday or Monday. I suppose I can post a picture when they arrive and someone can tell me if they think they are fake. Any telltale signs of fakes?

Thanks again guys -- I decided that the ESW9A's looked like the best bet. Plus, since they are made from padauk, they'll match my padauk amp.

Thanks for the suggestions -- lots of options it looks like. The headphone landscape has blossomed since the last time I looked. How would people compare these to the formerly expensive, but now on a big sale everywhere, A700's? Actually, it looks like these are both on sale -- $225 v. about $110. Worth the extra? If I go closed, then one of those, or DT770's all look pretty promising, though the 770's availability seems problematic.

Guys, I may be in the market for some headphones. Knowing next to nothing about what's out there, I could use suggestions. Basically, I own two sets of phones. Etymotic 4p's that I bought in 2001 or 2002, and RS-1's I bought in 2003. I use the ety's when I am on airplanes, and that's about it. They are kind of OK, but the banging cord is too annoying. I love the RS-1's -- enough that I haven't really thought about buying anything else for almost 6 years. But, I need some office phones. I am looking for $200 or less. Used is fine but they need to be findable quickly. Open is OK, but the Grados probably leak too much sound. Other things -- punchy (Grado-esque) bass would be good, and impedance should be low. Oh, and besides the fact that I don't like what they sound like, Senn 600's are horribly uncomfortable to me -- something smaller/lighter is good. Last, I listen pretty quietly which means that a little exaggerated bass is a good thing to me. And, even more last, being able to be balanced easily is also a plus as the amp I'll be using is balanced, though it is happy single ended so it isn't a big deal. Anything fit this bill? 225i's seem right except for the leaking sound -- any other options?

You just connect one side of the output to ground and it is single ended. PS looks a little lacking, but the design is nice. For more, look at the RAKK with passive output, same idea except here the chips are used NOS: Passive output

Vf is always dependent on current and ambient temperature. Just because it drops 1.5V in one place, does not mean it will somewhere else. MBR1100 is rated to drop 0.68V, but with a little warmth that will increase to 0.75. Use a pair in series.

If adding a shield solved your problems, then it means you need a shield. No shame in that. Shielded sockets are not uncommon: Here's my phono stage with shields If shields solve your problems, then it sounds like they aren't in this case. But yes, they can be a problem. Search a tube forum for "grid stoppers" for more info.

Pictures would help (particularly around the connections to the tube sockets), but it sounds like a combination of things. There could be some grounding issues and any competent tube tech should be able to fix those. Additionally, the tubes could be oscillating due to poor construction. Oscillation can manifest itself in a lot of different ways, from static, to hash, to squealing, to microphonics, to ringing. 6sn7's are not known for a propensity to oscillate, but any tube can, given the right (or wrong) environment. Really, you'll need a scope to know if this is the case, but if there aren't measures to quell oscillation taken, then adding them is as good a test as any. This means adding grid stopers, and in extreme situations not likely here, plate and catjode stoppers as well. The tubes could also be picking up interference of some sort which would be cured with some shielding. As a first go, try making shields out of aluminum foil and wrapping them around the tubes. Literally, this means wrapping a tube of aluminum foil around the tubes. Be sure they are grounded to the chassis -- probably touching the screw that holds the socket on will be good. edit: ah, you are using those dumb tube adapters? Almost certainly oscillation. Could be other stuff, too, but those were a bad idea from day 1.

Boy that's ugly. Cary deserves credit for being a big player in the tube and SET revival. Also, the 805 is a beautiful amp. But otherwise it is all a bit underwhelming. As you mention, there are some real issues with the amp designs, not only in sound quality, but also in basic abuse of tubes. I used to own a 303-200 cd player, but I designed my own DAC that sounds better, and if I can do that, then there is something wrong. I do like their knobs, though.

In general, the issue with Cary amps is in the power supply. Typically several large, slow, caps with resistors instead of chokes. Since the caps don't stick up on this amp, you could rebuild on the inside to fix this without it showing. You could also probably just add some small film bypasses for an easy fix. A quick Google search didn't pull up the schematic, but someone must have it. They also tend to run everything right at the edge of dissipation limits (tubes and components.) You should be able to dial things back a bit if you are willing to get in and get your hands dirty. But, you could also build a much better amp for way less money if you are willing to do that. As for the "upgrades" ... These are fine caps, but they are not that expensive. A pair in the required size is about $45 at parts connexion right now. I say that, but it may be that their phase splitter needs a whole host of caps. It isn't clear whether they use these for all 8 that are likely required in a Schmitt -- I tend to doubt it, but it is worth a look under the hood. I thought it used 5U4's ... Anyway, another $5 upgrade. Makes you wonder what the stock version uses. That's nearly $2 worth of wire to rewire that one input. And, even if you are prone to thinking that wire matters, if you can tell the difference between that and some other copper for that short run, you have better ears than me.

Meet the Fonkens

It is probably not ideal, but it is also not necessarily a huge concern. My experience says that the lower the Z out the better for Grados, but anything up to about 8 or 9 ohms will have a decent damping factor, and assuming enough current will perform fine. You could, of course, use a stepdown transformer/autoformer of some sort to improve things.