Post by bleekgill on Jan 21, 2012 13:12:23 GMT -5
After several satisfied months of living with a DecwareCSP2+ between my source and UPA-1's, I thought I’d write up a summary of my observations and potential insights.
The first thing I discovered is that the UPA-1's, as with many SS amps, aren’t an ideal match for many tube preamps. At 1.25V input sensitivity and 29-32db gain, they can be easily overloaded by 12-20db of tube preamp gain, potentially resulting in tube hiss and hum, as well as uneven channel balance at the low range of the preamp’s pot. The Emo’s relatively low input impedance might also result in rolled-off frequency extremes if matched to a preamp with high output impedance, although I didn’t experience this with my initial 1k+ unit. These technicalities aren’t an issue with SS preamps, but I wanted tube and had to go through some auditions before I came to grips with these audible realities.
This is where the CSP2+ eventually came to the rescue. The Decware is fairly unique in that it has adjustable L and R output pots that are separate from the main volume control and allow the user to match the gain of the amp. It is also interesting in it uses a large output capacitor to lower the impedance to levels easily accommodated by SS amps and longer cable runs. Some purists, even the guys at Decware (at least before they made this preamp) like to minimize the placement of these in the signal path, but this particular implementation appears work very well, besting some other impedance-lower methods. It definitely sounded much bigger and more transparent to me than another preamp that was coupled to my amps with high quality gain- and impedance-lowering transformers.
This high degree of technical matching has an awesome effect of my UPA1's. The soundstage is large, with huge 3D images, great bloom and transient decay, as well as SS-like detail from top to bottom. It can also be tonally natural, dynamic and extremely fast, but this really depends on the type of tubes you choose to use. Online reviews are misleading when authors don’t roll out stock tubes before making claims about agility, tonal balance, etc. This is disappointing. It isn’t easy for tube makers to keep a stock of the perfect NOS tubes for each of the models they make.
This is what makes tube ownership both challenging at times, but also fun and fulfilling. The only stock tubes I ended up retaining were the 6N1P-EV's in the driver positions. I have found the directly-heated 5Y3 rectifiers, especially the 5Y3G's, to be best for dynamics and speed. The indirect models such as that from MAZDA and Bendix can sound a little flat, at least in my system. Imaging, frequency extension and detail were also affected by the choice of input tube.
So in short this is preamp is a great technical and musical match for the Emo amps. It's a great option for those of you looking to venture into the world of tubes. Hope this review is helpful.
The first thing I discovered is that the UPA-1's, as with many SS amps, aren’t an ideal match for many tube preamps. At 1.25V input sensitivity and 29-32db gain, they can be easily overloaded by 12-20db of tube preamp gain, potentially resulting in tube hiss and hum, as well as uneven channel balance at the low range of the preamp’s pot. The Emo’s relatively low input impedance might also result in rolled-off frequency extremes if matched to a preamp with high output impedance, although I didn’t experience this with my initial 1k+ unit. These technicalities aren’t an issue with SS preamps, but I wanted tube and had to go through some auditions before I came to grips with these audible realities.
This is where the CSP2+ eventually came to the rescue. The Decware is fairly unique in that it has adjustable L and R output pots that are separate from the main volume control and allow the user to match the gain of the amp. It is also interesting in it uses a large output capacitor to lower the impedance to levels easily accommodated by SS amps and longer cable runs. Some purists, even the guys at Decware (at least before they made this preamp) like to minimize the placement of these in the signal path, but this particular implementation appears work very well, besting some other impedance-lower methods. It definitely sounded much bigger and more transparent to me than another preamp that was coupled to my amps with high quality gain- and impedance-lowering transformers.
This high degree of technical matching has an awesome effect of my UPA1's. The soundstage is large, with huge 3D images, great bloom and transient decay, as well as SS-like detail from top to bottom. It can also be tonally natural, dynamic and extremely fast, but this really depends on the type of tubes you choose to use. Online reviews are misleading when authors don’t roll out stock tubes before making claims about agility, tonal balance, etc. This is disappointing. It isn’t easy for tube makers to keep a stock of the perfect NOS tubes for each of the models they make.
This is what makes tube ownership both challenging at times, but also fun and fulfilling. The only stock tubes I ended up retaining were the 6N1P-EV's in the driver positions. I have found the directly-heated 5Y3 rectifiers, especially the 5Y3G's, to be best for dynamics and speed. The indirect models such as that from MAZDA and Bendix can sound a little flat, at least in my system. Imaging, frequency extension and detail were also affected by the choice of input tube.
So in short this is preamp is a great technical and musical match for the Emo amps. It's a great option for those of you looking to venture into the world of tubes. Hope this review is helpful.
