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SP8 preamp reviews

here's a couple photos of a finished SP8-SE preamp




by Bob Latino @ The Dynaco Tube Audio Forum

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 
original posting of review here

buy an SP8 preamp here


send us email at: info@tubes4hifi.com



Customer Comments . . . .

"Your kit certainly has a "faster" sound with better bass, both in quantity and in tone. 
I also find it very dynamic.  Your price is well worth it.  


Listening this afternoon was a joy. In a word, the preamp is neutral. It allows you to listen to the work done at the mastering console. I'm able to hear microphone techniques and how the engineer mixed the recording. For me, that's how an amplifier is supposed to "sound". Transient response is quick, you can hear all the subtleties and nuances in the recording. I do so enjoy listening to vinyl records, therefore I spent a goodly amount of time listening to the phono section. The first thing that I noticed was the neutrality of the amplifier. When the recording was well mixed & mastered, the amplifier passed it on without adding or subtracting anything. Playing CDs through the line section is a joy. It's fast, articulate, and allows the subtleties to pass. One thing that comes to mind is that it sounds so relaxed while reproducing the source. Frequency extension is right there. The high end extends to the limits of the recording without making me want to turn down the volume, or worse yet, turn off the system. The bass end is very tight and extends as deeply as the source. The middle range, well, what can I say? It makes you sit up and listen, and not because it's pronounced. It simply sounds neutral. “Correct”, as my wife said last night. I'm listening to the preamp daily. It's such a joy to listen the music.


I just got this note from a repeat customer of mine, who just recently bought an Audio Research SP8 on Ebay for $1000 . . . . . I start loosing interest in the Audio Research pre amp - it does not have the magic of music, the music is kind of harsh. believe me the VTA SP6 I borrowed from you is more pleasant to listen to, it is more musical and the music flows more easy, and the bass is way more detailed and controlled and extends way down. I am looking forward to listening to the new preamp from you. Thank you
I got your pre amp today, thank you. I listened to the pre amp for about one hour. The SP6 is more musical than any thing I listened to so far, I think your sonic grade of 6 in your web site is underestimated and needs a reevaluation! Thank you
> Roy, you asked how I liked your SP6 preamp. It sounded better than any of my other pre-amps, e.g., > Transcendent GG, Van Alstine OmegaStar, Dynaco PAS-4, > Bottlehead Foreplay 3, etc. > I really built it to see if you could produce a really good, pre-amp for under $600 and it certainly > filled the bill. The pre-amp is as good as any on the market selling for over $2000 (< $4000?). > I have only one tube pre-amp, a DIY 6H30, which can compete with it and the 6H30 is a little too euphonic > at times. Both the 6H30 and the VTA offer wider soundstage than the Bottlehead which gives the impression > of listening in a closet after you listen to eith the 6H30 or VTA. > The midrange and highs on the VTA really set it apart from most of the other pre-amps that I've been > listening to. The midrange has 'right on' spatial effects and the highs sparkle like many good pre-amps, > but the combination has that 'just right' sound. > Paul M.
Review: of the (Tubes4HiFi) VTA-SP6 Tube Preamp. Build: This is a simple kit to build that requires some experiance working with electronics, but can easily be accomplished by a beginner with a little help. Skills required: Use of a Voltmeter, Soldering Iron, Screwdriver, Drill, being able to identify electrical parts ie. resistors, capacitors, and diodes. Respect for High Voltage is not necessarily a skill but a necessity when working with tube gear. The line stage: I have had many different tube and solid state preamps over the last few years. to list a few Modified Dynaco PAS 3, Pat 5, NAD 1020, Audio Experiance, and others, and I have to say this preamps line stage betters the preamps I have used before. The VTA-SP6 has a majestic tube sound that would lend itself well to nearly any system. The separation and imaging is this line stages strong point, only to be bested by its incredibly fast bass response. The Phono: The phono stage was my main draw towards building this preamp. My initaial listening test thought was I just can't remember this much detail from my other Phono stages. So I connected my VP-129 Tube Bellari for an A/B comparison, I was right, the SP6 has much better detail, especially in the midrange. I was confused because to date the Bellari held the title for reasonably priced phono stages, so I rolled a few tubes throught the Bellari, but the detail is just not there. I really could not believe how much more detail I was hearing, and is this normal? It must be normal, because I like the way it sounds. In comparion to my beloved Bellari. The sound of the VTA-SP6 moved me into the front row. All of the LP's I have tested sound more life like and spaceous due to the SP6's phono stage. All in all the Tubes4HiFi SP6 is an exceptional value preamp that is reasonably simple to build, even for a beginner like myself. This was my first venture into building tube based audio gear and has been incredibly rewarding. Less than $450 invested. GotHover
I have gone through several solid state preamps (NAD, Adcom, etc.). I also tried a passive preamp with a homebrew phono preamp. All these gave me performances a lot to be desired. I have always wanted to try a tube preamp or two, but I was somewhat put off by off-the-wall prices of preamps that were worth considering. I guess the Dynaco PAS-2/3 would have been an option that can be had for under 200 bucks, but some tweaking (PS upgrade, recapping, and tone control removal) would have to be done to make it listenable. I figured that if I were to spend more than $200 on a decent preamp, I might as well built something new. After having done some research, I narrowed it down to the VTA SP-6. The preamp uses 2 NOS RCA 12au7s for the linestage and 2 TAD 12ax7s for the phono stage. This probably is the best sounding preamp that I owned so far. It sounds very neutral and lets all the subtleties in recording pass without any coloration. It's fast, articulate and versatile. I would recommend it to anyone who's serious about their audio stuff. Min


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