Mike are you running dummy buffers with the Sparkos ? I think I need to get Sparkos duals, no way to fit the Burson singles ;-(
Do you know what is best to put in the buffer socket to not stand in the way of current for planars...dummies, buffers or actual opamps ?
Currently using the AD797 and wideband buffers with caps due to the V5i's not fitting.
Hi Lohb,
Yes, I always use dummy buffers in the PB2, when using it with the HD800 or with my recently acquired DT880 600-Ohm (modified by BTG-Audio to use balanced cables).
I would love to have the current gain offered by using "real" buffers in the output stage, but the noise floor is
always lower when I use dummy buffers - as heard with highly resolving headphones. When using the LCD-2 rev.1, HD600, and HD650, for example, I cannot hear the increase in noise floor that comes with using "real" op-amps in the buffer stage - so with those headphones, I can enjoy the extra power that comes with using buffer op-amps, without feeling as if I am having to compromise the noise floor.
And speaking of power vs. noise... check out the comparison chart Sparkos Labs has published:
Source: http://sparkoslabs.com/wp-content/uploads/2014/06/SS3601_SS3602.pdf
Take this chart with a grain of salt, if you like (with it showing the SS360x having
more power and lower noise than the other op-amps listed), but I can attest that not only does a pair of SS3602 duals in my PB2 (with dummy buffers) exhibit an audibly lower noise floor than the Burson V5 duals in the same chain, they can drive my 600-Ohm balanced-cabled DT880 with terrific authority. The SS3602 is powerful, even with only the +/- 16V supply voltage of the PB2. The SS3602 is just coasting along with a +/-16V supply voltage (with the PB2 on external 16V power), given that they can handle supply voltages as high as +/- 22V (compared to the current edition Burson V5's +/-17V).
In looking at the data sheets of a lot of different op-amps, I've noticed that most op-amps tend to yield their lowest noise levels not at their absolute maximum permissible supply voltage, but rather at supply voltages that are roughly 85% to 90% of absolute maximum. Yes, they will give you more output power to your headphones if you can give them their absolute maximum supply voltage, but they will be noisier at their maximum permissible voltage. Consider how good a match the +/- 16V supply voltage of the PB2 is (on external power), with high gain, to the +/- 22V maximum supply voltage of the Sparkos, vs. the +/-17V maximum supply voltage of the Burson V5. Take note that I am assuming these two discrete op-amps behave a lot like most IC op-amps in terms of low noise at less than maximum power, which might not be the case, but in general, it just makes intuitive sense to me that an op-amp which is not maxed out will generate less noise.
The DT880 600 sounds a little compressed and has slightly uncontrolled bass when using only half of the SS3602 Duals via the TRS jack of the PB2, but when I switch to balanced cables, using the PB2's Hirose jack, the DT880 600 comes to life, finally getting enough power to be all it can be - with the tightest, most textured and detailed bass I've ever heard - way better than my LCD-2 rev.1 in terms of control and texture, even when the LCD-2 is connected to my Oppo HA-1's 4-pin XLR jack, that puts out 2000 mW into 32-Ohms. The bass energy (amplitude) of the DT880 600 is not as great as that of the LCD-2 rev.1, but that's a good thing, as I've long since "matured" in terms of how much bass energy sounds natural and real vs. simply "fun." The HD800 weaned me of my lust for bass, but the DT880 600, with balanced cables
and Beyer's pleather pads (instead of the velour pads), is "just right," as Goldilocks would say. I can also say that the Sparkos SS3602 plus DT880 600 has a more "musical" bass. The warp of a tympani drum, for example, is awesomely slurred through a range of low frequencies rather than sounding like a brief honking at a single frequency. I realize that I'm pitching the DT880 600, here, as much as I am the Sparkos SS3602, but the fact is, I don't get this level of performance with other op-amps in the PB2. After getting my DT880 600 back from BTG-audio having installed mini-XLR jacks for balanced operation, I ran through some of my favorite opamps with the DT880, not wanting to overlook any special synergies that might exist. Forget about it. The Sparkos SS3602 wins!
Basically, thanks to the Sparkos SS3602 duals, my precious PB2, and balanced output to the DT880 600, my HD800 is gathering dust (at least for the moment). Oh, the HD800 sounds great with the SS3602s but, it just can't muster the bass energy of the $220 DT880 600 with the $70 mod performed by BTG-Audio and Beyer pleather pads. The detail from top to bottom is spectacular. The noise floor is really low. And the treble doesn't have the smoothing "glow" around every note that the (too tall) Burson V5 Duals have. The Sparkos SS3602 yields so much blackness around even the lowest-energy signals, that the soundstage just blossoms. Micro-details against inky black backgrounds are the building blocks of soundstage - they map out the dimensions of the space in which the music was recorded, revealing the weakest of natural reverbs. The DT880 isn't known for having the big soundstage of the HD800, but thanks to the low noise of the Sparkos, the width and depth of the soundstage is surprising. The Sparkos also place you a lot closer to the stage, where the dynamics are more impactful and vocals more intimate and close (all but feeling the singer's breath on your face) than the Burson V5, where you find yourself sitting farther back from the stage - more laid back,less dynamic, with less "slam." I attribute the superior dynamics, the bass control and and the authority of drum hits and bass kicks to the SS3602's raw power. I'm running them with the PB2 jumpers set to high gain. If I were using much more efficient headphones, these power-related attributes wouldn't be as noticeable relative to the Burson V5s, but the difference in noise floor would be even more noticeable.
Note, however that
I am unable to fully seat the SS3602 into the PB2 sockets:
This has proven to be perfectly OK. They are staying put, with no evidence of rising up out of the sockets on their own, but
I have affixed a section of thick packing tape above the Sparkos op-amps, on the underside of the PB2's cover, to provide a non-conductive surface, just in case the SS3602s would touch the bare aluminum. I've used them with the lid on, without the packing tape, but I feel better having added the packing tape. There is no room under the PB2's closed case to insert a DIP8 extender.
All that said (I can't help myself thanks to be a fast typist), if I were using the Sparkos SS3602 with less than highly resolving headphones, I wouldn't hesitate to at least try using "real" buffer opamps - to get even more power (through additional current gain), but I would make some careful comparisons while listening with a track that has a lot of silence in it. I'm pretty sure "real" op-amps could be used instead of dummy buffers, without running into the SS3602s, but I haven't tried it.
Here's a recording with some silent spaces that really allow the Sparkos SS3602 to show off:
Heart Beat by Antonio Forcione Quartet
Mike
