Review: Promitheus Reference C-Core Preamplifier

Category: Preamps

I am adding this review mainly for the benefit of many regular integrated amplifier owners who have the ability to add a separate pre-amp and use their integrated as a power amp. I am doing this, because I was so frustrated trying to find information of using the Promitheus TVC with an integrated amp, and could find none. When I put together my audio system, I had an upgrade plan in mind, and when the time came, I could not find enough information on using an integrated amp as a power amp - especially with a TVC.
For regular people like me, who could not initially invest top $$$$ in hi-fi, a good integrated amp is a great start. Then a point comes where we feel the need to upgrade. This need comes when you hear other hi-fi systems, read reviews, visit forums and acknowledge the fact that your own system can be improved when you change/add/delete some component.
Though audio mags are used for reviews, I believe that forum participants/reviewers share an unbiased opinions, as they sponsor their own "buy", and I give the forum participants more weight than any mag. On the forums, folks share the positive/negative points that they felt in the component, and most readily accept the deficiencies if found. They are not paid writers. But there are times when, even the mags and forum participants agree on a cheap priced component that really is "value for money". One such component is the Promitheus TVC that I first read in Stereophile's Sam Tellig's column. I further looked up the Audiocircle forums and was really intrigued by this down-to-earth-priced component. I followed the threads over there and found the price of admission to be pretty low compared to the benefits that the folks there were getting. I read similar reviews and opinions on AudioAsylum and Audiogon and I got interested even more. I emailed to Nicholas who owns Promitheus and provided him with the sensitivity/output impedance and other details of my amp and my system. Nicholas was prompt in replying all my emails. He was confident that the TVC will work with my amp. But still I waited for another 3 months for getting more feedback from the community regarding the compatibility, just to be sure that I was not getting a wrong component. I got mixed results and decided that Nicholas knows his product the best.
After exchanging a couple of emails with some users of the TVC I decided to upgrade my system finally. Initially I decided on the Reference 4/5 version. But after exchanging email with a gentleman who owns the Signature Version, and other opinions of the C-Core topology on Audiocircle, I decided to go for the Reference C-Core version which costs $1370. The Signature Version costs much more. I also added the Elma Switches which cost me $320 more. The wait times for the product are a bit long. I had to wait 2 months before my TVC showed up at my door. I guess the TVCs are so much in demand.
The TVC arrived in 2 separate boxes. The packaging was pretty good and the TVC was packed in Styrofoam sheets and sitting between two big foam tabs. There were packing peanuts as well. The actual TVC looks a different than what we see on the site. It was much more substantial that I thought it would be. I did not like the instruction manual that came with it. It was 4-5 printed sheets with the photos to show how to connect the TVC. There are some other details in the pages too. Maybe this is for overall cost reduction. But I got the TVC connected in my system with its output going to the Main IN of my NAD C352 integrated amp. Of course, I had removed the Preamp-Main IN jumpers on the NAD. My listening room is 14’ X 11’ X 8’ with the speakers placed along the 14’ wall. The speakers are 8’ apart and 2’ from the back wall. Main source is the Marantz SA-8260 SACD player. Other sources are the Technics RS-TR575 Cassette Deck and Sony DVP-SR200P DVD player. I use the Sony player for playing MP3 disc loaned from friends, playing CDs loaned from public library or CDs that friends bring along. Sorry guys, no abused CDs on my Marantz. All cables are from Signal Cable – Silver Resolutions bi-wires for speakers, Analog IC 1 for MP3 & Tape Deck, MagicPower for Amp and Magic Power Digital Reference for the Marantz.

Before I connected the TVC system, I played the Steely Dan “Aja” CD on my then current system, just to memorize the “before” sound. Once all the setup was done, I switched my amp ON and put on a Steely Dan “Aja” CD. The TVC has 24 notches to go from MIN to MAX volume. I turned up the volume by 10 notches to get to the moderate listening levels that I was used to. The change that I noticed immediately from the “after” sound was that the bass was suddenly tight. It was as if the TVC took control of my Quad’s bass drivers. I definitely liked the sound from my system after connecting the TVC. The overall sound was better, but surely not $1690 better. But the user manual (pages) and some forum threads did mention that the TVC needed some 150 hours break-in period. Also I had new Signal Cable’s Silver Resolution interconnects between the TVC and NAD. That cable also needs about 50 hours of break-in. I was in no rush to break in. So I let my regular listening session break-in the TVC. One important point that Nicholas had mentioned that the source did not matter as much, as did the power amp. And I tried this by connecting my wife’s iPod to the TVC. I got the similar moderate volume level after I moved the volume up by 2 more notches (to 12). So for all the people who want to know if your MP3 player will work with TVC - the answer is yes. Note that my NAD C352 amplifier section’s input sensitivity and impedance is 770 mV / 20k ohms / 470 pF. If your integrated amp has numbers close to this, then this TVC is worth the try.

So as days passed by, the TVC got between 100-120 hours of break-in time. It is now approaching about 180 hours. But I did my critical listening after 130 hours. And this was specifically because I wanted to report to the community about the TVC and integrated amp combination. I enjoy it more as times go by. I started with Eric Clapton’s “Slowhand” SACD. On song 5 – We’re All the Way – the woman’s sound on the left sounded way out to the left and at least 2 feet at the back of the speakers. It was as if the room boundary on the left side had just been extended. This was an eye (ear) opener for me. With my older setup, I had heard her sound a bit to the left of the left speaker. It always used to remain attached to the speaker, but slightly at the back of it. I was pleasantly surprised by this experience. The TVC also transported me to a larger venue, with expansive sound stage than I am used to with my NAD. But then I should really not compare the NAD’s built in passive preamp to the TVC. The price parity is too much. The strings on this SACD sounded so real – as if they would jump out of the speakers. It reminded me why we all love live music so much. It is because live music had the “presence” and the TVC added that to my system. Sara K sounded to be right in my room when I played the “Hell or High Water” SACD. I was always impressed by this SACD even with the NAD integrated alone. But the TVC made it more natural. In the title song, the tin whistle came from left side of the right speaker and way back than what I was used to. As always, I enjoyed the entire album, but with more presence and channel separation this time. The TVC makes all the instruments sound natural. There music becomes so “fluid”. There is a sense of ease and naturalness to the instruments. I am really impressed by this nature of the TVC. The NAD, as an integrated was no match for the TVC. But one thing I was impressed about the NAD was the power amp section really showed what the TVC communicated to it. I am surprised with my NAD too, as I did not expect such good sound quality from this regular amp. The NAD now sounded a much different amp than what I heard from it before.

The Promitheus and NAD C352’s power amp section seem to match very good. For example, when I was listening to “I’ve Got You Under My Skin” from Diana Krall’s “When I Look InYour Eyes” SACD, the guitar in the first few seconds sounded so real, as if they were being strummed right in my room. Similar was the effect of the bass strumming in “East Of The Sun (West Of The Moon)” from the same SACD. I could “see” the strings being strummed!! Trumpets sounded – well just like trumpets - with such presence in “Why Should I Care”. I really was impressed by all this.
But something was bothering me during my listening sessions. The vocals, which should have come from dead center of the sound stage, were slightly to the right. Raising the Volume control on the Left channel corrected that. This seems incorrect. I went to the left speaker and tried to shake it. And it did wobble!! It was then I realized that the day before I installed the TVC in the system, I had toed in the speakers a bit more to get a better imaging. And I had completely forgotten to realign the Left speaker’s feet so that it did not wobble. Through the NAD I did not realize this issue. But the TVC was throwing precise images of the sound stage and the issue came to light. During the break-in period, I was just enjoying the music that came though TVC without critically listening to it. I assumed that all the deficiencies I was listening to, were part of the break-in. My mistake.

Once the speaker feet were set correctly the speakers did not wobble and the vocals were back in their original place. The imaging got tighter than what I heard previously. In fact the instruments now have their own space in the sound stage!! I got back the previous SACDs and gave them a listen again. They sounded even better, with the improved imaging. On Miles Davis “Kind Of Blue” SACD, the sound stage was so very wide. The sax seems to come from a foot or two from behind the speaker in “Blue In Green”. Normally the sax seemed to come from inside the speaker with my old setup. With the TVC in place the trumpets sounded very real on this SACD. On Madeleine Peyroux – “Half The Perfect World” CD – in the song “I Am All Right”, Dean Park’s guitar has it’s own space and identity instead of getting lost in the mix. I am not sure if I heard it with my previous setup. So when I heard it so clear, I picked up the booklet and made sure that there was indeed this extra guitar in that song. Instruments did not get lost in the mix. Finer details of guitar strings, tightness of bass strings etc, came out so naturally.
The imaging of this TVC is so superb that I am hearing the “moves” of the musicians. For example, on Jerry Lee Lewis’s CD “Last Man Standing”, I was listening to the song “Pink Cadillac” and I could actually see Dave Wodruff’s movement of sax of left of the sound stage – from left to middle and again to left. I was able to track his movements, which I was not aware of in my previous setup. For this CD I was transported to a large auditorium. Another point in case is the song “Willow Weep For Me” from Diana Krall’s CD “From This Moment On”. Jeff Clayton’s sax comes from left side. Even when I faced the speakers directly, the sax did not seem to come from the speaker. The sax seemed to come from beyond the speaker!! The ambience was just like a small jazz club and I was sitting in the front row. With the TVC in place, the bass, drums and other percussions now have “definition”. There are details that I don’t think I heard before. I believe that the professional reviewers may be referring this to the “inner details” – not sure. What ever it is – it is natural.
Rosemary Clooney’s “Girl Singer” is a very good recording and I have always enjoyed this SACD. The TVC made this sound so natural. In the song “Of Course It’s Crazy” the guitar on the right sounded so “distinct” – as if a separate space and mic was allocated for it. The ultimate test for the TVC came in the form of “Blue Coast Collections” SACD. And this is not in terms of sound quality or imaging – but in terms of creating a “live” session in my room. The sound quality of this disc is no doubt very good. But I always felt the songs of this disc pretty boring. But the TVC somehow made this disc sound interesting to me. I decided to play this disc as background music as I started to write this review. But damn, it just would not let me continue. I just could not concentrate. So I shut off my laptop and got involved with the music. The song “Lillianna” demoed the guitar in the middle and the Jose Blanco slightly to the right –excellent imaging. But I was actually getting along with the music – even though I do not speak or understand Spanish. Similar was the effect on “Slow Day”. I began to appreciate the music on this disc. The TVC reminded me why we audiophiles love this hobby!! Live music draws you, even when there is just 1 person with a guitar or a harmonica. It is spontaneous and of course you are “present”. I feel that this is the change that the Promitheus TVC brought to my system. It has brought a “presence” in my system, to a degree that I find it very difficult to play background music on my system. If I have to do background listening, I have to turn down the volume at least by 4-5 notches. And still it remains noticeable that I lift my head up and try to “see” the music.
But is the Promitheus TVC a magic bullet for all issue of a recording? Absolutely not!! On the contrary, the TVC is damn too revealing. For example, I purchased the “Raising Sand” CD recently, as I have always liked to listen to Alison Krauss. Thought the music on this disc is pretty good, the recording mix is muffled and dark. I have a thread on the Asylum and people have similar feelings. So the TVC did not magically improve the mix. But on CDs that sound narrow and where the instruments got lost in the mix, the TVC can give such CDs some life by creating space and trying to separate the instruments in space. “The Very Best Of Sting and The Police” CD is case in point.
Last but not the least – I am beginning to enjoy the mono records as much as I do stereo. Mono songs in “The Definitive Collection – Louis Armstrong” have bands and background vocals. With my previous setup, the entire band was holed up in the center of the stage. The Promitheus TVC now creates a wide center stage thus separating the instruments, background and lead vocal. I feel as if the sound got “broader” and “breaths easy” because of the space.

I could go on and on, but I am really enjoying the TVC, and am short on listening hours. There were days where I sat ready with my notepad but forgot to write the notes, because the music became so engrossing. There is a sense of “ease” and “naturalness” that the TVC has brought to my system. Some glare in the CDs like “ABBA Gold” has either gone or reduced considerably. Instruments simply seem to jump out of the speakers and form in air mid way between the speakers. At this point I feel that this TVC is worth more than what it costs. I feel that owners of integrated amp whose amps can be used as a power amp should try this TVC in their system and see what their systems are really capable of. This will generally apply to the integrated in the range of <= $2000 range. This is just a guess. I may be right or wrong. But in case of my system – I was ABSOLUTELY right. I have read people diss passive preamps and TVC on many forums. In the case of this TVC, they would be dead wrong. I have exchanged emails with folks on Audiogon/AudioCircle/Asylum who have compared the TVC to mega buck preamps and in many cases the Promitheus TVC has actually come out on tops and by a large margin.

In my previous threads on Audiogon and Asylum I was trying to decide, if I need to upgrade my integrated or start with a preamp. I am glad that I went ahead with the Promitheus TVC. It is indeed the best audio investment have I made. Now-a-days I just wonder and dream how a pair of very good mono blocks can improve my system. I will look forward to upgrade to some mono block amps in the near future – used of new. I am leaning towards the Wyred 4 Sound SX 1000. But this will have to wait.
years ago they sent me a broken promitheus passive pre and expected me to fix that myself
the pre should be sent back to the company but they did not accept that kind of service
I sold that for $200 to a person who has the ability to fix that
That is pretty unfortunate. Hopefully they have improved their customer service policy. I saw that they had a review in Stereophile a month or two back. At they had requested their "circle" to be closed a couple of years back. But they are listed there as well.
I should say though, their TVC sounds fantastic, at least, in my system, where I have matched the gain and other parameters.
I have owned two Promitheus passives, a ref 4 and a double C core signature. I loved both of them, and bought both of them used to avoid the notorious wait and problems in importing a new one. As far as reliability and customer service, there is not much that can go wrong with these. It's just a much easier route to wait for a used one already in the US than it is to place an order and wait months for it to be built and shipped. And for those who receive an unit that is not working properly, you go through the ordeal all over again.
Buy used and sit back and enjoy. The used Promitheus TVCs are the best bang for the buck out there in my opinion.
What was your conclusion between the TVC and the Statement? Do you still have both in your system?
Milipai, The C-core statement was a clear upgrade over the Ref 4. Crystalline highs with the statement is probably the most immediately obvious and striking difference between the two.

I sold the Ref 4 after I purchased the Statement. The statement has been replaced by the Coincident Line Stage. At $5500, the Coincident should be expected to outperform the Promitheus Statement and it does. I held on to the Statement as something I might use to start a bedroom system in the future. Its just too good a piece to let go of until I'm sure I won't use it again. If you have a passive friendly system, I just don't see how you can touch it in terms of bang for the buck.
I agree with you on the C-Core. Pretty happy with my Reference C-Core. And my system has been matched to be passive friendly, although it is a solid-state only system and average speaker sensitivity. I am planning of getting a new CDP in the near future that has XLR out. This will provide me with even more gain, which is good for the TVC.
I believe you are referring to the "Signature" version, when you are saying "Statement" version of the TVC.
there was not used promitheus in agon at that time
Milpai, Correct on the Signature.
Jmlab, Yes, one has to be patient in waiting for one to come up used. On the other hand, there are numerous stories about people waiting months after placing an order for a new unit.
Nicholas really needs to set up a North American distributer who has inventory to allow potential customers to circumvent all of these frustrations in ordering new units. Maybe he has all the business he wants, but I think a lot more people would be using these TVCs if they knew how good they were.
he does not know how to run a business I did not give him a negative feedback
and there are other passive and active preamps around
I agree that Nicholas needs to do a better job.
With there recent review in Stereophile, I am assuming that they have [probably] changed their mode of operation. But it will take them quite some time to regain the popularity that they lost to all the negative feed backs. Unfortunately none of the feed back was for their products. All of them were for services.
If you look up the Audio Circle's forum an entrepreneur from the US wanted to represent him in the States, but things did not work out. I am assuming Nicholas must have had some thing going on in his mind for the future, hence that project did not materialize. I am hoping they have changed and the new buyers do not have to go through the long wait times.