pp312 Posted May 2, 2011 Posted May 2, 2011 Just thought I'd post here in the hope someone has a little more info on this little amp: http://cgi.ebay.com.au/NE5532op-amp-Power-tube-HIFI-Headphone-Amplifier-/220773961536?pt=AU_Electronics_Audio_Amplifiers&hash=item3367274f40 It's almost certainly the same amp as is discussed here: http://rockgrotto.proboards.com/index.cgi?board=b&action=print&thread=6013 which is intriguing enough, but even more intriguing is that it's also almost certainly based on the same circuit as Onkyo use in their upmarket integrateds and receivers (5532 op amp, BD139/140 transistors, 2200uf power caps), which is discussed here: http://www.head-fi.org/forum/thread/357405/onkyo-dx-7555-vs-headamp-gs-1-vs-onkyo-a-9555 and favourably compared to a well-respected $800 dedicated HP amp. Why am I interested in this? Because I own an Onkyo 9555 integrated which uses this circuit and I'd like to know more about it--plus it would appear to be something of a real bargain if published impressions are any guide. It certainly sounds the business through the Audeze LCD-2 I'm using it with, but I just wondered if anyone had bought one of the Ebay amps and if so what they thought. If not, maybe someone would like to invest $50 and let us all know.
Frederick Posted July 6, 2011 Posted July 6, 2011 I think if you are looking for a specific type of headphone then the best way is to search for them online. Online market has got tremendous scope and it is always better to use this resource to fulfill your requirements. So, you can use internet and get the specific headphone online.
pp312 Posted July 10, 2011 Author Posted July 10, 2011 Wow, it only took two months and four days to get a reply to this thread. Forums are really great--I'll have to start another thread just for the heck of it. Thank you, Frederick, but back in the old days when I started this thread, before I became senile, I was looking for info on the link between those various designs, which apparently nobody possessed. Not to worry...
Monkeyboi Posted July 11, 2011 Posted July 11, 2011 Wow, it only took two months and four days to get a reply to this thread. Forums are really great--I'll have to start another thread just for the heck of it. Thank you, Frederick, but back in the old days when I started this thread, before I became senile, I was looking for info on the link between those various designs, which apparently nobody possessed. Not to worry... Hi Paul, The problem mate is you don't post enough - LOL. I've used the NE5534AN (single op-amp version of the NE5532) in numerous projects over the years with complete success. Albeit a dated IC by today's standards it can perform remarkably well if implimented in the correct circuit design. Likewise the Philips BD139 / 140 transistors are well proven over the years. I've used them in high output power amplifiers as drivers for the output devices, once again with a lot of success. Just too a quick look at the ebay ad. For $43 + postage you really can't go wrong, but you'd need to team it with a decent power supply. Cheers, Alan R.
bruce108 Posted July 11, 2011 Posted July 11, 2011 . . . you'd need to team it with a decent power supply. They seem to cost upwards of $200 (Welborne, Little Pinkie) and more if aimed at specific products like the Squeezebox. That's a disincentive! Assuming that a good psu can really make 30%-40% difference to SQ - which I remember hearing. Any way out of this?
pp312 Posted July 11, 2011 Author Posted July 11, 2011 Howdy, Alan. The point of my original post was that the three links all appear to refer to the same highly regarded design. You're right: for the price you couldn't go wrong with the Ebay version (but doesn't it come with its own power supply--or is that just not up to scratch?). However I've since entered more heavyweight territory with a Matrix-M Stage for my LCD-2s--a nice amp, but not really a huge leap over my modest, $130 Muse amp (an Aune Mk1 clone, for those into Ebay headphone amps). I've never been a great believer in amps making a huge difference, and experience has borne me out (or is it just that my ears aren't good enough?).
Monkeyboi Posted July 11, 2011 Posted July 11, 2011 They seem to cost upwards of $200 (Welborne, Little Pinkie) and more if aimed at specific products like the Squeezebox. That's a disincentive! Assuming that a good psu can really make 30%-40% difference to SQ - which I remember hearing.Any way out of this? I found a schematic for the headphone amp listed on ebay after I made the post. It uses a 12v a.c. supply with a minumum recommended current rating of 0.8A. What surprised me is the amplifier uses only half wave rectification with not a large amount of smoothing (only 2200uF per rail) feeding standard LM7912 and 7812 series regulators for a +12 and -12v differential supply, so other than a suitable transformer with decent line and load regulation, I can't see too much that can be gained without modifying the internals of the headphone amp. Cheers, Alan R.
Monkeyboi Posted July 11, 2011 Posted July 11, 2011 Howdy, Alan. The point of my original post was that the three links all appear to refer to the same highly regarded design. You're right: for the price you couldn't go wrong with the Ebay version (but doesn't it come with its own power supply--or is that just not up to scratch?). However I've since entered more heavyweight territory with a Matrix-M Stage for my LCD-2s--a nice amp, but not really a huge leap over my modest, $130 Muse amp (an Aune Mk1 clone, for those into Ebay headphone amps). I've never been a great believer in amps making a huge difference, and experience has borne me out (or is it just that my ears aren't good enough?). You can still get this headphone amp. It comes supplied complete with the power supply for about AU$42.00 http://www.ebay.com.au/itm/NE5532op-amp-Power-tube-HIFI-Headphone-Amplifier-/320726335792?pt=UK_MusicalInstr_Amplifiers_RL&hash=item4aacc78130 Cheers, Alan R.
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