Product Review -
Sound Valves VTP-101i Preamplifier - September, 1996
By John E. Johnson, Jr.
|Sound Valves, Inc.,185 North Yale Avenue|
|Columbus, Ohio 43222|
|Phone 614-279-2383; Fax 614-279-0368|
|E-Mail firstname.lastname@example.org URL www.soundvalves.com|
Sound Valves VTP-101i Preamplifier; Vacuum tube preamplifier; Cathode follower circuit; Regulated cathode heater; Frequency response 20 Hz - 20 kHz plus or minus 0.1 dB; Sensitivity 50 mv for 0.5 Vrms output; Maximum output 10 Vrms; THD < 0.015%; Slew rate 12 V/microsecond; Input impedance line level 80 kOhms, phono input 47 kOhms; S/N > 95 dB; Inputs: Phono, Tuner, CD, Video, Aux; Two tape loops; One external processor loop; Size 3 3/4"H x 17"W x 10 1/4"D; Weight 13 pounds; $799; Warranty 3 years parts and labor; Choice of black or gold anodized faceplate.
The first time my daughter saw a tube amplifier (last year) she said, "Cool!" Tubes have made a resurgence, and big time. Many people have been buying them partly because they look very attractive with the lights out and the cathodes glowing. Of course, the novelty of their looks has now waned a bit, and we are seeing more tube equipment with covers on them, at least the preamplifiers. Sound Valves has been making solid state amps and tube amps for several years now, and have enjoyed growth in both areas. We reviewed their limited edition solid state MOSFET 32B stereo power amplifier some time ago, and unfortunately, it is now sold out. Why? Because it was a great amp at an unbelievably low price. That is what Sound Valves (used to be called Sound Values) specializes in: bang for the buck. The VTP-101i is a stereo tube preamplifier that has lots of features, including a phono stage and gold plated jacks, all for $799. If you are not into tubes (yet), that is INEXPENSIVE. (You could pay $799 or more just for a tube phono stage.) They do it by dealing direct. No showroom, no dealerships. The disadvantage here is that you have to buy one before you can listen to it, unless your friend has one. But, of course, there is a 30 day money-back guarantee so you can try it out without risk. It only weighs 14 pounds in the box, so return shipping by UPS is cheap. But I don't think you will return it.
The VTP-101i uses six SOVTEK 12AX7WXT tubes, three for the line level section, and three for the phono section. If you buy a high-end solid state preamp these days, a phono section is likely to be available only as an option. Tubes and vinyl have long been love birds, so the preamp section (it will handle both MM and MC phono cartridges) is standard on the VTP-101i. When the power on switch is depressed, a red LED illuminates, indicating that the cathodes (filaments) are heating up (the power supply is solid state). After about 30 seconds, the LED turns green, indicating that the amp is ready for use. During the heating stage, the preamp is muted. The 12AX7 is a dual-triode, and the pair of triodes from each tube are split into the left and right channels of each section of the amplification stages in a single ended, pure class A configuration (single ended designs have to be run in class A, while push pull - more typical of power amplifiers - can be run either in class A or Class A/B). Since both triodes of a dual triode tube are in the same glass envelope and under exactly the same vacuum level, having the left and right channels processed at any one stage in the same tube helps to ensure that the signals for both channels are handled in an equal manner. Of course, this increases the chances of crosstalk between channels, but the VTP-101i manages to keep this down to -80 dB.
The front panel has, from left to right, the Input Selector (phono, tuner, CD, video, aux), Tape Monitor (for the two tape loops), Balance L/R, Volume, External Processor Loop (EPL) button, Mono button, Mute button, and Power on/off button. The rear panel has a grounded AC jack, ground lift switch (to reduce hum from ground loops), two sets of output jacks, external processing loop jacks, two sets of tape loop jacks, tuner input jacks, CD input jacks, video input jacks (the audio from a VCR or laserdisc player for example), auxiliary input jacks, phono input jacks (input and output jacks are all RCA gold plated), and phono impedance switches (100 kOhms/47 kOhms; 120 picofarads/220 picofarads). I told you this preamp has a lot of features!
We tested the VTP-101i with several of our reference components and cables, including the Silver 9t, Sunfire, MOSFET 32B, SE-1, Nordost Flatline, AudioQuest, as well as some other products currently under review. Interestingly, this unit is designed with the home theater enthusiast in mind. The external processing loop (EPL) has one set of inputs and outputs. The idea is to connect the EPL output jacks to one of the sets of inputs on a surround sound processor, let's say Video 1. Then, you connect the line level output of the front left/right channels from the surround sound processor (of course, this assumes you have line level outputs on the processor) back into the EPL inputs. The preamp main outputs are connected to two channels of power amplification, which drive the front left/right main speakers. Here is the way it works. When you want to play CDs in standard stereo, you turn on the VTP-101i and your two channel power amp. If you want to play CDs in surround sound mode, or when you want to watch movies with surround sound, you turn on the VTP-101i, all power amplifiers, and the surround sound processor. To play CDs in surround mode, switch the VTP-101i to CD input, depress the EPL button, and switch the processor to Video 1. The CD stereo output of the VTP-101i will be sent to the Video 1 input on the processor, and the front left/right surround sound info will be fed back to the VTP-101i. The rest of the surround sound will be fed by the processor to the other amps (which could be the ones inside the processor or outboard power amps). If you are using a VCR or laserdisc player, switch the input of the processor to this source, and it won't matter which input is selected on the VTP-101i. The EPL circuit is after the inputs but before the volume control, so both volume controls (VTP-101i and processor) are active. This way, you get the advantages of tube sound to the front left/right main speakers even when listening to surround sound. Neat!
The VTP-101i has a typical tube sound: sweet, melodic, and a full bodied mid-range. We found it especially nice when using electrostatic speakers and ribbon speakers which have very sharp detail, since this results in reduced listening fatigue (tubes have a characteristic softening of edges in music, and CDs sometimes have a metallic edgy sound to them). There was a noticeable break-in period (about 20 hours) after which the preamp obtains its full sonic signature. The preamp also needs a warm-up period for each use (it is not recommended to leave a tube component on all the time). Now keep in mind that the tube sound is not for everyone, because there is a definite warmth to the music that is different than the razor sharp analytical quality characteristic of solid state. Tubes have a very lush mid-range which some people like and others don't. As a compromise, you might try pairing this preamp with solid state power amplifiers, which is what we decided we liked best. MOSFET power amps will have a more tube-like sound, while bipolar output device power amps will deliver a fast crunch. On the other hand, if you really like tubes, then by all means, pair the VTP-101i with a tube power amp.
In summary, Sound Valves has done a fine job with the engineering of the VTP-101i. It has quality construction, loads of features - including the ability to use it in a home theater surround sound system, a great price, and, of course, that tuuuuuuuuuuuuube sound you just gotta love.
John E. Johnson, Jr.
Thank you for your review of Sound Valves' VTP-101i tube preamp. We claim "Affordable Tube Components-100% Conceived, Designed, and Built in the USA." We're delighted you found our preamp to have "lots of features" and "INEXPENSIVE." We work hard to deliver full value-100% built in the USA.
Our "dealerless" FACTORY-DIRECT policy does save the customer money (usually 20-50% over comparable dealer distributed products). But there's more to the story. . .
Our 30-day audition period allows the customer to conduct what may be the only truly valid listening test- A SUBJECTIVE TEST WITH ONE'S OWN GEAR IN ONE'S OWN ROOM. It is SV's position that dealer demonstrations are frequently more misleading than enlightening. This is because both the dealer's components - and listening area - have little or nothing in common with the customer's home system and listening environment.
Finally, a lively debate rages in audio circles as to which is more important: the tube amplifier or the tube preamp. While our VTP-101i certainly works well with our 140/140W SV250 MOSFET amp, we believe that there is genuine synergy in using both tube amplifier AND tube preamplifier. In our listening, using tubes at the front and back end produces the optimal result. Gone is the flabby, ill defined, and not particularly deep bass of 1960s tube amps. Our modern tube designs produce deep bass and detailed extended highs . . . without the shattering glass "hash" so often associated with solid state components.
John Peterson, President
© Copyright 1995, 1996, 1997 Secrets of Home Theater & High Fidelity
Return to Table of Contents for this Issue.