Roy Mottram, the designer of the VTA driver board and the SP-6, SP-8 preamps, was kind enough to ship me one of his wired and tested SP-8SE (Special Edition) "kit" preamps for evaluation. This preamp is 16 inches wide by 4 1/4 inches high and 12 inches deep and weighs in at a healthy 11 1/2 pounds. The preamp has four high level inputs and one phono level input. It has one tape loop and two outputs on the back. The two outputs are handy if you biamp at times as I sometimes do. The front panel has a left gain and right gain control and a master volume control. The master volume control is a stepped attenuator with 24 levels of volume. The left gain and right gain controls have 12 levels of gain and allow you to alter the gain of each channel independently (and subtly) effectivly giving you a "balance" control. The control on the far right is an on/off/mute control. The lamp under the on/off/mute control changes from green to red when the preamp is in the "mute" mode.
Internally the preamp is laid out very cleanly with the entire circuit on one board and a number of neat sets of wires going to the preamp's controls. The board uses two 12AU7 tubes (line stage), two 12AX7 tubes (phono stage) and one 12X4 rectifier tube. The striking component though is the large, 4 1/4 inch diameter, 4+ pound torroidal power transformer. Personally, I have never seen this large a power transformer in a preamp KIT before.
I connected the preamp to my personal 60 WPC ST-120 tube amplifier. The ST-120 was connected to my Tyler Acoustics Linbrook II speakers biwired through home made speaker cables using Canare 4S11 speaker cable. The signal source in this system is a Nakamichi CD player sending the zeros and ones to a Bel Canto DAC2 D/A converter. This preamp is quiet with zero hum and only the tiniest bit of "hiss" when I placed my ears ON THE GRILLECLOTH of the Linbrook II speakers. A foot away from the speakers you could hear nothing! This preamp scores high in the "cleanliness" category.
Playing various CD selections, I was really impressed with the bottom end response of this preamp which was every bit as good as my BAT VK3i preamp which I normally use on this system. The BAT VK3i uses 4 6DJ8 tubes and with its remote and phono board is a $3000 preamp. The SP-8SE's top end was clean, smooth and "effortless" and its sound character did not seem to be altered when the volume went up. Many kit preamps starve for power when the volume goes up because the power supply was skimped on to keep the price of the kit preamp down. Not so in this case. With the ST-120 amp, I found that the two gain controls worked well at their 12 o'clock (center position). With the two gain controls set there and the master volume at 12 to 1 o'clock, the sound was pretty loud. In all honesty I would have to say that the sound quality was as good as my BAT VK3i at about 1/3 the price of the BAT. The BAT does have a remote and 140 volume steps but if you don't need a remote and can get by with the 24 steps in the SP-8SE you can save yourself a bunch of money.
I then brought the SP8-SE to my big downstairs system and put it in place of the other BAT preamp that I have - a BAT VK30SE tube preamp which uses four 6H30DR tubes. This is a $6000 tube preamp with it's remote and phono board. The phono board in this preamp, by the way, is the same as the one in the upstairs BAT-VK3i. In the downstairs system I have a Music Hall MMF-7 turntable with a Goldring Eroica H moving coil cartridge with a Geiger II line contact stylus for spinning vinyl. In this system the SP8-SE was running into a Bryston 4B-SST 500 WPC (into 4 ohms) power amp and then biwired to two Magnepan MG 3.6R planar magnetic 4 ohm speakers. I played both CD's and vinyl though this system. The CD's were handled by a Classe CD-1 CD transport into another Bel Canto DAC-2 D to A converter that I have. The SP-8SE acquitted itself very well against this far more expensive BAT preamp. If I had to make a definitive choice for best sound quality I would probably go with the BAT for slightly superior sound staging and a smidge more bass from the BAT. IMHO the SP8-SE aquitted itself very well against a preamp costing more than 6 times what the SP-8SE kit sells for ($800). With respect to cost vs. performance the SP-8SE is really tough to beat.
The SP-8SE is the finest tube preamp KIT I have personally heard. I have also auditioned in the past the Dynaco PAS-3, Bottlehead Foreplay and Audio Electronic Supply AE-3 tube preamps that were built from kits. Roy also sells the main SP-8SE board and parts kit separately for $209 + $11 shipping. The main board may be installed in your Dynaco PAS-2, PAS-3 or PAT-4 preamp for huge increase in sound quality. For more info on the SP8-SE and other photos and options on this preamp visit the tubes4hifi web page at the link below.
The Tubes4hifi preamp page
Bob
Internally the preamp is laid out very cleanly with the entire circuit on one board and a number of neat sets of wires going to the preamp's controls. The board uses two 12AU7 tubes (line stage), two 12AX7 tubes (phono stage) and one 12X4 rectifier tube. The striking component though is the large, 4 1/4 inch diameter, 4+ pound torroidal power transformer. Personally, I have never seen this large a power transformer in a preamp KIT before.
I connected the preamp to my personal 60 WPC ST-120 tube amplifier. The ST-120 was connected to my Tyler Acoustics Linbrook II speakers biwired through home made speaker cables using Canare 4S11 speaker cable. The signal source in this system is a Nakamichi CD player sending the zeros and ones to a Bel Canto DAC2 D/A converter. This preamp is quiet with zero hum and only the tiniest bit of "hiss" when I placed my ears ON THE GRILLECLOTH of the Linbrook II speakers. A foot away from the speakers you could hear nothing! This preamp scores high in the "cleanliness" category.
Playing various CD selections, I was really impressed with the bottom end response of this preamp which was every bit as good as my BAT VK3i preamp which I normally use on this system. The BAT VK3i uses 4 6DJ8 tubes and with its remote and phono board is a $3000 preamp. The SP-8SE's top end was clean, smooth and "effortless" and its sound character did not seem to be altered when the volume went up. Many kit preamps starve for power when the volume goes up because the power supply was skimped on to keep the price of the kit preamp down. Not so in this case. With the ST-120 amp, I found that the two gain controls worked well at their 12 o'clock (center position). With the two gain controls set there and the master volume at 12 to 1 o'clock, the sound was pretty loud. In all honesty I would have to say that the sound quality was as good as my BAT VK3i at about 1/3 the price of the BAT. The BAT does have a remote and 140 volume steps but if you don't need a remote and can get by with the 24 steps in the SP-8SE you can save yourself a bunch of money.
I then brought the SP8-SE to my big downstairs system and put it in place of the other BAT preamp that I have - a BAT VK30SE tube preamp which uses four 6H30DR tubes. This is a $6000 tube preamp with it's remote and phono board. The phono board in this preamp, by the way, is the same as the one in the upstairs BAT-VK3i. In the downstairs system I have a Music Hall MMF-7 turntable with a Goldring Eroica H moving coil cartridge with a Geiger II line contact stylus for spinning vinyl. In this system the SP8-SE was running into a Bryston 4B-SST 500 WPC (into 4 ohms) power amp and then biwired to two Magnepan MG 3.6R planar magnetic 4 ohm speakers. I played both CD's and vinyl though this system. The CD's were handled by a Classe CD-1 CD transport into another Bel Canto DAC-2 D to A converter that I have. The SP-8SE acquitted itself very well against this far more expensive BAT preamp. If I had to make a definitive choice for best sound quality I would probably go with the BAT for slightly superior sound staging and a smidge more bass from the BAT. IMHO the SP8-SE aquitted itself very well against a preamp costing more than 6 times what the SP-8SE kit sells for ($800). With respect to cost vs. performance the SP-8SE is really tough to beat.
The SP-8SE is the finest tube preamp KIT I have personally heard. I have also auditioned in the past the Dynaco PAS-3, Bottlehead Foreplay and Audio Electronic Supply AE-3 tube preamps that were built from kits. Roy also sells the main SP-8SE board and parts kit separately for $209 + $11 shipping. The main board may be installed in your Dynaco PAS-2, PAS-3 or PAT-4 preamp for huge increase in sound quality. For more info on the SP8-SE and other photos and options on this preamp visit the tubes4hifi web page at the link below.
The Tubes4hifi preamp page
Bob
