the opamp used in the zhaolu is opa2604
the best sound is opa627bp
the best buy is ad823an
copied from
http://www.rock-grotto.co.uk/opamp.htm
Test one: LF 353 Price: £0.40p
This is the op amp that comes supplied with the kit and it really doesn't do the amp much justice sounding shrill, grainy and very "in your face". It is actually very similar sounding to the valves that come supplied with the musical fidelity X-Can V2... on some high notes the LF 353 can produce ear bleeding harshness. Remove this (don't fit it in the first place) and go for something better if you want to hear the amp at its best. 4.5 / 10
Test two: Burr Brown OPA 2604 Price: £2.50
OPA2604 sounded very warm, very laid back and very easy to listen to but slightly veiled in the detail department. "Chocolaty" and "syrupy" though a good easy to listen to Op amp but not my cup of tea as I prefer a greater insight into the mix. Having said that, however, this may just be what the doctor ordered for those who like a laid back, thick, chocolaty, easy going and easy to listen to sound. 6.5 / 10
Test three: Burr Brown OPA 2228 / 2227 Price: £3.00
These chips makes the sound more valve like than the X-Cans ever did if that can possibly make any sense! (I couldn't detect any sonic differences between the 2227 & 222 Melodious, slightly laid back and warm yet it brings out every last bit of detail from a recording. Overall a very nice sound. A kind of hybrid valve and solid state mix which gives the best of both worlds. Nice smooth valve like mids and highs with lovely solid state bass oomph . This is the Op amp for those who prefer a valve like sound but would also like a solid state bottom end delivery. With this Op amp you can have your cake and eat it. 7.5 / 10
Test four: Burr Brown OPA 2132 Price: £4.00
Smooth, highly analytical, warm, uncoloured, laid back yet all detail is present (and then some) Very electrostatic quality to the sound with that super solid state bass underpinning the proceedings without overwhelming them. Start and stops are followed by an inky black silence and the timbre of the drums is very realistic indeed. Something that is very evident with this op amp is it's inherent ability to provide accurate timing which I really do like! There is no bass overhang, the drums start and stop as they should and, as a result, the timing is pretty much spot on. This is like listening to music with a stethoscope with the metronome ticking away in the background but it also adds a touch of valium to make the experience very bearable and extremely enjoyable. 7.5 / 10
Test Five: AD 823 AN (Analogue Devices) Price: £3.00
Without a shadow of a doubt this op amp is the star of the show so far. From the moment I rolled this into the amp I knew it was a winner. It provided very similar results to the OPA 2132 but each component of the sound was treated to an additional air of realism and effortless delivery that was immediately evident. Easy to listen to, easy to pick out every last detail and ever so natural. There was an ethereal quality to the sound that I have only ever heard on high quality loudspeaker based systems. It's hard to put what this op amp does into words but listening to the sound with it on board is as close to headphone heaven I have yet been. 9 / 10
Test Six: AD 712 JN (Analogue Devices) Price: £4.50
A "Very" revealing chip, similar to the AD823 but rougher around the edges. I don't know if the roughness was on the actual recording or if it was attributable to the AD712 but I found this chip gave out "way" too much information for my liking. It is analytical to the point that certain pieces of music can become impossible to listen to, especially bad recordings, it reproduces every last detail / imperfection with microscopic accuracy which, at times, can be detrimental to the overall enjoyment of the music. For those that love a warts and all insight into the music then this is the star of the show but it may not be to everyones liking. 8.5 / 10
Test Seven: Burr Brown OPA 627 BP on Browndog adaptor Price: £28 each (Total £56 for 2 singles) Browndog adaptor £5 Total: £61
Two words sum this chip up........ "absolute class" This is the only single chip in the test (the rest all being duals) and it was necessary to fit two single channel 627's onto a single to dual Browndog adaptor which Adapts two single-channel DIP-8 op-amps to a dual DIP-8 pinout. These 2 single channel op amps absolutely trounced anything that had gone before them in this test..... the width of the soundstage, the clarity and the sheer presence make this my choice of op amp for use in the Chiarra without a shadow of a doubt. The sound is just so "clean", so "natural", so "musical" and so "detailed" with the 627's on board. I said the AD 823 was "as close to headphone heaven I have yet been" The Burr Brown 627 "is" headphone heaven....... absolute class act. 10 / 10
