| HOME | Dynaco mods | Service & Mods | Links | Downloads |
Preamps
SP-6 / SP-8 preamp
This is our "mid-range" preamp that has received excellent reviews from everyone that has tried it.
This has just been updated/upgraded to our SP-8 designation in February 2009.
Based on customer comments we can safely call this . . . .
the best preamp in the world under $2000 !! .
It uses a classic tube preamp circuit which includes phono stage, line stage, and power supply all on one PCB.
The PCB is sized so that it can be used in a new chassis, or will fit into an existing Dyna PAT4 chassis (NOT recommended to fit into PAS3)
This design will give you extremely high value on your dollar compared to any other DIY kit that we know of.
Available as a PCB only ($89) or PCB parts kit in 2 versions ($189 or $209).
Our new update for this PCB is the option of adding regulated B+ and/or regulated filament power with just a few parts.
For tube purists you might want regulated filaments but unregulated B+ power, choose the options your way,
or add them later after you've had a chance to listen to this great preamp design.
The circuit has a hi-gain phono preamp using a 12AX7 gain stage followed by a highly accurate passive EQ,
followed by another 12AX7 gain stage, for a total gain of 45 db.
The line stage uses a 12AU7 in a cascode SRPP gain stage for high gain with excellent linearity and low output impedance,
for a gain of 15 db. The power supply uses a 12X4 tube rectifier for soft-start, and uses DC power for the filaments
to reduce noise.
The basic version (SP6) uses a standard PAS3 (PA211) transformer for power
The enhanced version with regulation (SP8) uses a choice of conventional or toroid transformer
with the correct voltages needed for regulation of the B+ and filament power supplies.
We also offer your choice of custom made chassis; or using a vintage Dynaco PAT4; or use your own chassis.
please note - NO shipping outside USA for preamp kit please note - this kit is NOT recommended for beginners!! Hopefully you've successfully built a tube amp and/or preamp before, we DO provide a few pages of BASIC assembly instructions, but NOT a full blown 50 page step-by-step manual.
If you need additional help building this, we will highly suggest you let us finish it for you at a labor rate of $50 per hour, Stuffing the PCB takes about 2.5 hours.
Wiring this into an existing preamp chassis such as a PAT4 takes about 3 more hours, but if you are building a completely new preamp in a new chassis, you can figure 8 to 10 hours of total labor time.
We mention this because about 30% of our customers don't realize what is involved, and we end up spending 4-6 hours of rework to get it right.
 to order bare PCB (for SP6 or SP8) for ($89 + $6 shipping) click here: |
 to order the basic PCB (SP-6) kit with parts (tubes NOT included) for $189 + $10 shipping click here: |
| to order the enhanced PCB (SP-8) kit with parts (tubes NOT included) (including B+ and filament regulation) for $209 + $11 shipping click here: |
 to order the enhanced PCB (SP-8 including B+ and filament regulation) completely ASSEMBLED and ready to install (tubes NOT included) for $320 including shipping click here: |
| to order the basic power transformer for SP6 version for $40 + $5 shipping ($45 total) click here: |
to order the enhanced conventional power transformer for SP8 regulated version, (fits better with small chassis) for $50 + $5 shipping ($55 total) click here: |
to order the enhanced toroidal power transformer for SP8 regulated version (fits great in our large custom chassis) (this is HUGE, 4.5" diameter, 4 pounds heavy!) for $45 + $10 shipping ($55 total) click here: |
| to ADD the TUBE set to your order above, for either version (includes 2 each 12AX7, 2 each 12AU7, and one 12X4) for $55 plus $5 shipping click here: |
 set of ALPs volume and balance controls - $50 plus $4 shipping |
|
 Special Edition 24 step volume attenuator (compare at $100) $40 plus $5 shipping |
Special Edition dual mono gain/balance 12 step attenuators $20 plus $3 shipping | |
| sealed silver contact selector switch - $7 plus $2 shipping (compare to others at $30) | sealed silver contact OFF-MUTE-Power switch - $7 plus $2 shipping | Special Edition input relay selector PCB simplifies input/selector wiring and labor - $49 plus $5 shipping |
| Special Edition resistor & coupling capacitor upgrade package to PRP and Takman resistors (as used in $5000 preamps) and SoniCaps (similar to AuriCaps at half the price!)- $75 |
||
 VTA preamp chassis unfinished includes top, bottom, front, and rear panels $90 with shipping |
 custom drilled and engraved front panel 4N - $75 |
 Special Edition custom drilled and engraved front panel 5N - $75 |
 custom drilled and engraved rear panel - $65 |
8 pair of gold plated RCA jacks - $40 plus $5 shipping | IEC AC input connector and power cord - $9 plus $3 shipping |
| set of 4 aluminum knobs - $20 plus $2 shipping | set of 5 aluminum knobs - $25 plus $2 shipping | set of 4 large rubber feet for chassis - $3 plus $2 shipping |
| COMPLETE CHASSIS kit includes chassis, custom 4 knob front and rear panels, ALPS volume & balance controls, selector switch, off-mute-power switch, RCA jacks, IEC AC input and cord, feet, etc everything above except the PCB kit, transformer, and tubes $350 + $20 shipping |
| COMPLETE standard SP8 kit, all parts needed for complete preamp including PCB kit, tubes, enhanced transformer, chassis, custom 4 knob front and rear panels, ALPS volume & balance controls, selector switch, off-mute-power switch, RCA jacks, IEC AC input and cord, feet, etc $699 + $30 shipping |
| COMPLETE Special Edition SP8 kit, all parts needed for complete preamp including PCB kit, tubes, enhanced transformer, chassis, custom 5 knob front and rear panels, 24 step volume and dual mono 12step gain/balance controls, upgraded resistor and capacitors packs selector switch, off-mute-power switch, RCA jacks, IEC AC input and cord, feet, etc $799 + $30 shipping |
here's a couple photos of our latest SP8-SE preamp handbuilt by Roy (Vacuum Tube Audio)
finished preamp priced at $1190 - special order only
here's a recent review of this preamp
send us email at: info@tubes4hifi.com
see this review of the SP6 version with photos and info on the Klipsh audio forum
http://forums.klipsch.com/forums/t/114302.aspx?PageIndex=1
this photo shows the PCB installed in a Dyna PAT4 chassis
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
send us email at: info@tubes4hifi.com
see this review of the SP6 version with photos and info on the Klipsh audio forum
http://forums.klipsch.com/forums/t/114302.aspx?PageIndex=1
this photo shows the PCB installed in a Dyna PAT4 chassis
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
return to HOME page
|
| |
|
|