I guess I just became an Audiophile!
I've been listening to hours of music everyday for as long as I can remember but have never owned anything better than cheap head band / inner ear phones, the one ninety nine kind from Walmart (ASDA).
I decided to bid on some decent headphones thinking I'd maybe go insane and spend thirty or fourty pounds. I kept getting out bid a few pounds from their new price.
After that happened a few times I started getting anrgy and figured "Forget it, just buy some new!". A few days later and I now have a pair of ultra sexy Sennheiser HD650's!
I don't have any kind of system. My system is my computer's sound card at the moment. Suprisingly, considering it's a cheap computer to start with, it can actually drive the headphones reasonably well. Loud enough that I'm bothered about the cones distorting, as that was usually the end of the cheaper headphones (Is this also true of more expensive phones?).
But the one thing I've read as a constant for headphones like this is that they usually benefit from having a dedicated driver.
I've looked at the solid state amps but thought it might be nice to try for a valve driver. Information on this is quite limited on the net. There also seems to be an equally limited source of reasonable quality transformers.
I know Sowter produces a Mu-Metal headphone transformer that has a tap at 300 ohms. The headphones are 300 ohms so that would seem to be a possible option. But they're not particularly cheap transformers, over a hundred each. And they're driving relatively low powers.
I'd hoped with headphones I'd be able to keep the cost reasonable since I'm starting with a massively reduced power rating compared to normal speakers. I guess I just want to be careful that I don't end up paying hundreds more for something that doesn't quite shine as brightly as it should for it's cost.
Then with Mu-Metal I have to start thinking about inductors / constant current sinks etc since I think the Sowter transformers are for single ended use.
I'd like to ask for some advice on possible amp topologies, noteworthy valves for headphones or where I can find reasonably priced quality transformers that would do these headphones justice without then exceeding their capability.
Ideally I'd like to follow the Audionote theory on design of keeping it simple and just using higher quality parts, rather than having lots complex tweaking points and options all over.
I'm willing to go for things like the Sowter Mu-Metal transformers but it's like I say, whether or not I'm going to notice that much of a difference.
Please hit with some ideas, particularly if you've tried them yourself!
I've been listening to hours of music everyday for as long as I can remember but have never owned anything better than cheap head band / inner ear phones, the one ninety nine kind from Walmart (ASDA).
I decided to bid on some decent headphones thinking I'd maybe go insane and spend thirty or fourty pounds. I kept getting out bid a few pounds from their new price.
After that happened a few times I started getting anrgy and figured "Forget it, just buy some new!". A few days later and I now have a pair of ultra sexy Sennheiser HD650's!
I don't have any kind of system. My system is my computer's sound card at the moment. Suprisingly, considering it's a cheap computer to start with, it can actually drive the headphones reasonably well. Loud enough that I'm bothered about the cones distorting, as that was usually the end of the cheaper headphones (Is this also true of more expensive phones?).
But the one thing I've read as a constant for headphones like this is that they usually benefit from having a dedicated driver.
I've looked at the solid state amps but thought it might be nice to try for a valve driver. Information on this is quite limited on the net. There also seems to be an equally limited source of reasonable quality transformers.
I know Sowter produces a Mu-Metal headphone transformer that has a tap at 300 ohms. The headphones are 300 ohms so that would seem to be a possible option. But they're not particularly cheap transformers, over a hundred each. And they're driving relatively low powers.
I'd hoped with headphones I'd be able to keep the cost reasonable since I'm starting with a massively reduced power rating compared to normal speakers. I guess I just want to be careful that I don't end up paying hundreds more for something that doesn't quite shine as brightly as it should for it's cost.
Then with Mu-Metal I have to start thinking about inductors / constant current sinks etc since I think the Sowter transformers are for single ended use.
I'd like to ask for some advice on possible amp topologies, noteworthy valves for headphones or where I can find reasonably priced quality transformers that would do these headphones justice without then exceeding their capability.
Ideally I'd like to follow the Audionote theory on design of keeping it simple and just using higher quality parts, rather than having lots complex tweaking points and options all over.
I'm willing to go for things like the Sowter Mu-Metal transformers but it's like I say, whether or not I'm going to notice that much of a difference.
Please hit with some ideas, particularly if you've tried them yourself!
There are a few here http://headwize.com/projects/index.htm
and here http://www6.head-fi.org/forums/forumdisplay.php?s=&forumid=6
look out for the OTT 6C33 and 6AS7 creations by kevin gilmore.
And there is this http://www.tubecad.com/2004/blog0011.htm
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60586
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60585
and here http://www6.head-fi.org/forums/forumdisplay.php?s=&forumid=6
look out for the OTT 6C33 and 6AS7 creations by kevin gilmore.
And there is this http://www.tubecad.com/2004/blog0011.htm
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60586
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60585
Hi there,
I am at the moment working on a simple headphone amp using ECL82's. Do a search on the forum under ECL82 and Headphone, it should bring it up. This will be a very simple headphone amp, and by no means will it be high spec but th great advantage will be that been parafeed,I can use cheap 12VA toroidals as output transformers. All in all I expect the project to cost no more than ?100.00
Otherwise do a google search under "Headwize projects" which should bring up a whole section on valve headphone amps.
Good luck
Shoog
I am at the moment working on a simple headphone amp using ECL82's. Do a search on the forum under ECL82 and Headphone, it should bring it up. This will be a very simple headphone amp, and by no means will it be high spec but th great advantage will be that been parafeed,I can use cheap 12VA toroidals as output transformers. All in all I expect the project to cost no more than ?100.00
Otherwise do a google search under "Headwize projects" which should bring up a whole section on valve headphone amps.
Good luck
Shoog
Thanks everyone!
I've been having a read and look around and think I'm going to try a single stage, single ended amp by Andrea Ciuffoli; SESS Headphone Amp
The amp is nice and simple with only a few components, which means I have more money available to spend on each.
However, the power supply for the amp is something I'm not totally sure about.
This is pretty much exactly the same as a design from Lundahl; Hybrid Power Supply
This will be my first audiophile amp, but for guitar amps I've found I usually prefer the more upfront and defined sound of solid state rectification. So I think I may get rid of the valve rectifier and replace it with some high quality, soft switching diodes, perhaps Schottkys. Otherwise, I think I'd be concerned I might end up with something a bit too smooth sounding for my liking.
Something that bothers me about the supply is the use of three 20H chokes, which seems like quite a lot. Again, I'm more used to guitar amps where a single 10 / 20H choke will be the only inductor in the supply, resulting in a noticeable amount of hum.
It also appears that he's using 350V capacitors on the left and right channels to account for any transients to 350V as the supply fluctuates. Since the channels are only meant to be ~179V each, could I force the channels to be better balanced so's that I could use 200 / 250V capacitors here instead?
I'm tempted to just split the two channels totally to get a true monoblock form. Since I'll probably using solid state rectification I wouldn't have to worry about another valve heater winding, valve socket, valve, and having higher voltage windings to begin with for the valve rectifiers. I'd also get rid of the need for using 350V capacitors.
I've been having a read and look around and think I'm going to try a single stage, single ended amp by Andrea Ciuffoli; SESS Headphone Amp
The amp is nice and simple with only a few components, which means I have more money available to spend on each.
However, the power supply for the amp is something I'm not totally sure about.
An externally hosted image should be here but it was not working when we last tested it.
This is pretty much exactly the same as a design from Lundahl; Hybrid Power Supply
This will be my first audiophile amp, but for guitar amps I've found I usually prefer the more upfront and defined sound of solid state rectification. So I think I may get rid of the valve rectifier and replace it with some high quality, soft switching diodes, perhaps Schottkys. Otherwise, I think I'd be concerned I might end up with something a bit too smooth sounding for my liking.
Something that bothers me about the supply is the use of three 20H chokes, which seems like quite a lot. Again, I'm more used to guitar amps where a single 10 / 20H choke will be the only inductor in the supply, resulting in a noticeable amount of hum.
It also appears that he's using 350V capacitors on the left and right channels to account for any transients to 350V as the supply fluctuates. Since the channels are only meant to be ~179V each, could I force the channels to be better balanced so's that I could use 200 / 250V capacitors here instead?
I'm tempted to just split the two channels totally to get a true monoblock form. Since I'll probably using solid state rectification I wouldn't have to worry about another valve heater winding, valve socket, valve, and having higher voltage windings to begin with for the valve rectifiers. I'd also get rid of the need for using 350V capacitors.
It's overkill for a headphone amp that needs 20 mA or so per channel... what DOES matter is supply ripple. Single-ended stage has little rejection of power supply noise, and headphones are very sensitive. But no reason you can't achieve the same hum level with CRCRC filtering... you WILL need bigger caps. And you MUST take care with grounding.
I'd probably look at Brodie's transformerless circuit myself...
I'd probably look at Brodie's transformerless circuit myself...
eeka chu,
To answer your original (parenthetical) question:
"I don't have any kind of system. My system is my computer's sound card at the moment. Suprisingly, considering it's a cheap computer to start with, it can actually drive the headphones reasonably well. Loud enough that I'm bothered about the cones distorting, as that was usually the end of the cheaper headphones (Is this also true of more expensive phones?)."
The cones of Sennheiser HD650s just won't distort, at least not until
it's so loud that you go deaf or get a brain haemorrage!
The reason for the distortion is no doubt that the sound card can't
swing enough voltage or current (probably voltage in the case of
the 300-ohm Sennheisers). So what you get is amplifier clipping.
Any decent dedicated headphone amp should solve that problem.
Morgan
To answer your original (parenthetical) question:
"I don't have any kind of system. My system is my computer's sound card at the moment. Suprisingly, considering it's a cheap computer to start with, it can actually drive the headphones reasonably well. Loud enough that I'm bothered about the cones distorting, as that was usually the end of the cheaper headphones (Is this also true of more expensive phones?)."
The cones of Sennheiser HD650s just won't distort, at least not until
it's so loud that you go deaf or get a brain haemorrage!
The reason for the distortion is no doubt that the sound card can't
swing enough voltage or current (probably voltage in the case of
the 300-ohm Sennheisers). So what you get is amplifier clipping.
Any decent dedicated headphone amp should solve that problem.
Morgan
Morgan L said:
The cones of Sennheiser HD650s just won't distort, at least not until
it's so loud that you go deaf or get a brain haemorrage!
The reason for the distortion is no doubt that the sound card can't
swing enough voltage or current (probably voltage in the case of
the 300-ohm Sennheisers). So what you get is amplifier clipping.
Any decent dedicated headphone amp should solve that problem.
Morgan
Thanks, that's good to know. I'm so used to having headphones die on me that I'm paranoid that these might go the same way.
I play music loud sometimes, loud enough that I couldn't listen to it for more than hour or so, but I'm always listening out for any kind of rasp, hiss, popping, clicks or resonances that sounds like the cones are being overdriven. I have been hoping that since these phones cost so much more the cones are over-rated enough that they'll last years before they come close to distorting audibly. I play the guitar so I'm used to people purposefully pounding their speaker cones into submission at their maximum wattage since cone distortion actually sounds really nice with an electric guitar (Hendrix, Van Halen...).
I've decided I'm going to go for Andrea Ciuffoli's SESS amp since I like it's simplicity. I was trying to decided between the 6H30 and 417A (5842) versions but found a lot of people praising the 417A on the net as being one of the best, if not the best, sounding B9A's you can get. Some complained of noise but I found a site by a guy who'd actually bothered to do some measurements and comparisons. On it's own the 417A was the quietest of all the valves he tested, slightly more than four times quiet than the 12AU7. It also has the lowest plate and cathode resistances.
The main jibe is that RIAA equalisation emphasises the noise band of the 417A it would seem. But even still, the 417A is only low to moderately noisey, about have as noisey as the 112AU7.
Click here to read about his measurements. They're very interesting if you're looking at preamps.
I've also decided that I'd like to be be able to play LPs, so the gain of the amp on it's own won't be enough. Rather than build two separate boxes I'd like to just glue them together in one to save on mechanical effort, interconnects, all that kind of stuff.
I think the gain of another 417A (~47) won't be enough on it's own. From a rough guess I think I'd need something like an 12AT7 (ECC81), 5751 or a 12AX7 (ECC83). The noise of an AX7 is just over half that of the AT7, but I don't have any info on the 5751's noise. I'm also used to seeing the 12AX7 from the guitar world!
Does anyone have any opinions on the sounds of those three valves or suggestions for alternatives? Using the 417A for the phono stage I'd either need more than one of them or a high output cartridge. High output guitar pickups rarely ever sound as good as the lower outputs.
I think I've kind of made up my mind on the 417A as the output valve, but any advice on an extra gain stage or bias voltages for the 417A would be great.
It's interesting to hear he sells Lundahls.
At first I checked out Sowter transformers here in the UK since I didn't want to start thinking about international shipping of transformers. But Lundahl do seem to be excellent value for money. The cores are C form and the resistances of things like their 20H chokes, totally from memory, are about half that of Sowter's, for the same price. Pretty neato! Now all I have to do is check the international postage and hope it doesn't make all that value disappear.
Did you check out this one? http://headwize.com/projects/showfile.php?file=ahammer2_prj.htm I like the OTL (saves money on a part that I don't fully trust to be transparent), it's non inverting, and the topology is comfortable to my SS mind. I plan to use a ECC99 for the output because my Sennhiesers are 60 ohm (HD570)
Other than thinking, I'm not committed.
Other than thinking, I'm not committed.
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