Promitheus TVC passive preamp anyone?

fredgarvin · « **Reply #20 on:** 22 Sep 2006, 04:08 pm »

Thanks for the review Gymane! I had been planning to order a Promithius myself but bought an IRD Purist first and I am very happy with it so don't plan on changing. I also love its zero gain setting and its transparency. If I ever do feel like experimenting, your review solidifies the Promithius as the next unit up.

PaulFolbrecht · « **Reply #21 on:** 23 Sep 2006, 03:26 pm »

I've got one on order - one with a metal case. After bugging Nick about it for a bit, he decided to try it. I'm paying a bit more for this.

I have high expectations based on what I've heard. It will be a couple weeks at least, I'm sure, before I see it (paid him a week or so ago I think).

Paul

Bwanagreg · « **Reply #22 on:** 23 Sep 2006, 03:47 pm »

Newbuyer, your instincts were dead on. The hum was being generated by my Paradisea DAC, which was a few inches above the TVC. Once I moved it further away the hum disappeared. I can work with this placement limitation. I will also try some of the Cardas' on the unused inputs - they have a very high pitched noise present when selected, which isn't a problem in normal use but it is distracting.

So now I'm down to one problem - the bad 10th detent.

I took a photo for Nick to show the broken wire - not hard to find - and though you guys might like to see it.

This really is a nice looking little unit. Note the broken wire sticking up behind the volume pot on the right.

For grins, here is how I received the second package from DHL.

If you are going to puncture the box, don't blow a hole through the "Fragile" sticker... jeez!

My wife and I listened to the new MFSL CD of Zappa's masterpiece We're Only In It For The Money last night. The remastering is really amazing, and they found a much better master tape to work from, making this almost 40 year old recording sound beter than I have ever heard it. The sound of my little system was fluid, detailed, layered, and jaw dropping at times. I swear it sounds like I added a nice warm (and $) tube preamp to the system. I'm definitely a tranny convert like Gymane.

Next up is trying my battery powered Tripath amp in this system.

GHM · « **Reply #23 on:** 23 Sep 2006, 07:17 pm »

Thanks Greg for the pics and the little review. Man they banged that box pretty darn good!!
You think the broken wire is making it even more sensitive to the Dac? Like an antenna of some sort? My guess is once the undamaged one arrives, your hum problem will disappear along with the high pitch noise... neither of which I'm getting at the moment.

Hopefully soon you'll have your replacement.

Glad you can at least listen too it until the replacement arrives. I'm also happy to know my hearing isn't playing tricks on me. For thinking this TVC gives off such an organic sound.

Paul..wishful thinking on a couple of weeks. I wouldn't start looking for it... for at least a month.

Hope that metal chassis doesn't screw up the organic sound.

PaulFolbrecht · « **Reply #24 on:** 23 Sep 2006, 07:52 pm »

You may be right. Fortunately for me, I have a pair of Welborne 45 SET monoblocks to build before I need it, and I'll be amazed if I'm done before it arrives! :-}

(Nick - if you're reading this - I really need that thing ASAP.)

aa

bikes and beats · « **Reply #25 on:** 23 Sep 2006, 10:51 pm »

Hello,
I'm always looking for improvements to passive preamplifier designs. I had a CI Audio passive for a couple weeks and I must say that I didn't care for the sound. Detailed but NOT dynamic. What do the transformers in the Prometheus do? I have a tube pre now that's tube rectified and I like it fine but this.... this Prometheus has me thinking. One less device to plug in. Also, I'm running NuForce 8.02's. Any feedback on whether this would be a good combo? Oh, and how many ins and outs does I have. I'd like two outs so I can go direct to the sub.
Alright!
-MikeO

GHM · « **Reply #26 on:** 23 Sep 2006, 11:58 pm »

Quote from: bikes and beats on 23 Sep 2006, 10:51 pm

Hello,
I'm always looking for improvements to passive preamplifier designs. I had a CI Audio passive for a couple weeks and I must say that I didn't care for the sound. Detailed but NOT dynamic. What do the transformers in the Prometheus do? I have a tube pre now that's tube rectified and I like it fine but this.... this Prometheus has me thinking. One less device to plug in. Also, I'm running NuForce 8.02's. Any feedback on whether this would be a good combo? Oh, and how many ins and outs does I have. I'd like two outs so I can go direct to the sub.
Alright!
-MikeO

Hey Mike what are you using as a source? The Promitheus has two outputs and four inputs. Not thin at all..take the notion of all passives being thin and throw it out of the window. It doesn't exist with this unit. Why? I have no earthly idea.

What I do know is this thing makes REAL music. It has the dynamics of any active preamp I've heard. What it doesn't add is that forced sound you get from some SS active units. Once you hear it you'll understand what I mean by this. Some active or passive preamps make the top end thin and highlighted. Or they tilt the sound to the lower frequencies.This is probably my biggest gripe with the ones I've heard or spent any time with.

I've listened to more music in 4 days than I have in the last 3 months... Since this unit arrived.This unit makes you want to listen. The more I listen the more I can't get over how good this thing is! I've got music here that I've had for nearly 10 years. I'm discovering there is music on these disc that I've never heard..I truly mean that.

There was a time I thought if I go directly from the source to the amplifiers I would get the most transparent sound..that idea is long dead. What I got was musical but fatigue in some cases. The top end would have that over shoot. You know ...for example when a guitarist is strumming the strings and at some point it gets sharp and almost painful. That doesn't exist with this preamp in the chain.

I'm not going to hype it..it will speak for itself, all you have to do is listen.

Also what kind of speakers do you use? My system is all SS. I'm willing to bet the average audiophile wouldn't know this by listening.They would assume there are tubes some where in this system.

Good listening

bikes and beats · « **Reply #27 on:** 24 Sep 2006, 12:26 am »

Quote

I'm not going to hype it..it will speak for itself, all you have to do is listen.

aa

Too late, you already did!
I have 2-way DIY floorstanders that are likely ~88db efficient. I need some power with these. One day I'd like to have a set of full range drivers, but I have no plans for this currently. Anyway, I wouldn't have asked about this tasty pre if I didn't think the price was worth the risk. Very tempting! I like the wood enclosure and I hope they are still available.
One more thing....
Is the Interconnect type and length as important with the TVC as for other passives? Should I plan on getting Prometheus Silver IC's with the pre?
Thanks,
-Mike

bikes and beats · « **Reply #28 on:** 24 Sep 2006, 12:28 am »

Oh, my source is a Sony 3100es DVD/SACD player.
It's.... okay.

-Mike

GHM · « **Reply #29 on:** 24 Sep 2006, 12:42 am »

..you would have to email Nick about the output. It should be compatible..but who knows? Hey..I'm just excited about this unit. I've spent thousands and hadn't found this sound. Just a happy camper.

I just wanted to give you an idea of the sound. Which is tough when it must be typed in words.

I forgot to add that I haven't used his cables. I use 3 ft cables with no problems.
But I also use a buffer..so again I'm not sure about how long you could go.

Good listening

denjo · « **Reply #30 on:** 24 Sep 2006, 01:01 am »

GHM
I share your joy and new found musical enjoyment! Although I have not heard the Promitheus, I "know" the sound as I have sound musical nirvana with a TVC as well - Bent Audio TAP (silver trannies). You are absolutely right about that "tube-like" quality. The sound is transparent and pure. Its as if all veils have been lifted for the listener to get right into the heart of the music!

It will be interesting to read 6Moons' forthcoming review of the Promitheus (and the Bent Audio TAP, now Music First)!

Enjoy!

Best Regards
Dennis

GHM · « **Reply #31 on:** 24 Sep 2006, 01:07 am »

Thanks Dennis it is always good to read someones found that audio nirvana. From your words..you understand exactly where I'm coming from. I look forward as well to the reviews.. I really enjoy this hobby when I discover something new too me and exciting. it's like coming to the end of a long road race..refreshing!

All the best,
Gymane

NewBuyer · « **Reply #32 on:** 24 Sep 2006, 05:23 am »

Quote from: Bwanagreg on 23 Sep 2006, 03:47 pm

Newbuyer, your instincts were dead on. The hum was being generated by my Paradisea DAC, which was a few inches above the TVC. Once I moved it further away the hum disappeared. I can work with this placement limitation. I will also try some of the Cardas' on the unused inputs - they have a very high pitched noise present when selected, which isn't a problem in normal use but it is distracting...

I too hear this high-pitched noise when I select an unused input of the Promitheus TVC. I just tried a pair of RCA shorting plugs on one of the unused inputs - and now when I select that input, it is entirely silent.

As these plugs short the RCA positive/ground, I'm guessing the EMI prefers this straight-path to ground (instead of into the transformers) when the input is selected.

Interconnect length is not as critical for a transformer volume control as it is for other passive pre's. This is largely because the TVC's effectively lower the output impedance received from your source, making it much easier to drive subsequent interconnects and presenting a much easier load to your amplifier. This is a consequence of how attenuating transformers operate, and also accounts for why TVC's sound so much better then almost all other passives. There is a very nice FAQ on the promitheusaudio.com site about this.

Edit: Changed the above to read "RCA shorting plugs" instead of "Cardas RCA Caps"...

GHM · « **Reply #33 on:** 24 Sep 2006, 08:41 am »

Thanks New Buyer for your help. Is there a cheaper alternative to the Cardas RCA Caps? Does another company make these? Thanks

Hey Dennis..I was just notified I'll get a chance to compare a Bent Audio NOH to the Promitheus in a few weeks. I'm looking forward to playing with it also. It will be fun! aa

denjo · « **Reply #34 on:** 24 Sep 2006, 09:05 am »

GHM
That sounds very interesting! Look forward to your views between the two.

Best Regards
Dennis

NewBuyer · « **Reply #35 on:** 24 Sep 2006, 10:17 am »

Quote from: GHM on 24 Sep 2006, 08:41 am

Thanks New Buyer for your help. Is there a cheaper alternative to the Cardas RCA Caps? Does another company make these? Thanks...

I was mistaken in calling these plugs I'm using Cardas RCA Caps (I just edited the above post to correct this) - the plugs I'm using are all-metal RCA shorting plugs. They look similar to the Cardas product, but they also have the center RCA pin and so provide a true short, unlike the Cardas. I'm not sure where to source all-metal RCA shorting plugs - I wonder, can somebody here please suggest a source? But if you don't mind a plastic outer shell (instead of all-metal), Calrad has RCA shorting plugs for under a dollar per piece.

JLM · « **Reply #36 on:** 24 Sep 2006, 03:27 pm »

As I understand, the reason for insensitivity to I.C. lengths and sound improvements from other passives is all in the use of the transformers that take care of impedance mismatches between source and amps (provides a big synergy help), like an active pre-amp but without gain or extra components, versus typical volume controls that change impedance with volume.

According to Srajan at 6 moons (a tube fan), he'd recommend the TVC with tube amps and a good tube pre-amp like the Modwright with solid state amps. But I'm sure as always YMMV and its all system synergy dependent.

I'm feeling an early x-mas present to self coming on...

Bwanagreg · « **Reply #37 on:** 24 Sep 2006, 09:32 pm »

By concidence there is another thread discussing shorting plugs.

These look promising.
http://tweakshop.com/Shorting%20Plugs.html

NewBuyer · « **Reply #38 on:** 24 Sep 2006, 10:04 pm »

Quote from: JLM on 24 Sep 2006, 03:27 pm

...versus typical volume controls that change impedance with volume...

The TVC changes impedance with volume too, in that the more you lower the volume, the lower the signal impedance seen by your amp. This is a great feature especially for low-volume listening where dynamics can otherwise be compromised. The TVC does not match impedances, but it helps resolve impedance mismatches (as you said) by outputting a lower impedance version of the source signal than the original source could deliver. This improving the bridging impedance ratio, maximizes voltage transfer through your IC's, and presents a much easier load to your amp. The amp still sees wild impedance variations from the speakers, but Nick is now selling output transformers to put between amp and speakers that should provide yet another major sonic improvement.

GHM · « **Reply #39 on:** 24 Sep 2006, 11:51 pm »

Thanks for the links on the plugs guys. I'm still looking through the pages trying to find the $1.00 deals.

JLM,
I read several reviews saying the same thing. This is what kept me away from the TVCs. I was afraid it would be etched or over emphasis the highs.

Not a problem with the Brine's. I think it is the speakers that are being used in the review causing this problem. It's definitely not the TVCs from my listening so far. As I remember the speaker used in the review only has a resistor or capacitor in-line with the tweeter? Maybe this type of speaker isn't a good match for the gainclone? I know of one owner who sold his Gainclone and TVC because he got harsh or hard highs with the Zu speakers.

I wonder how the transformers designed to go in-line between the amplifier and speakers, would compare to the zobel that is already in place ? This is designed to allow the amplifer to see a steady load if I'm not mistaken. Maybe this is why I don't hear the problems in the 6moons review mentioning the mismatch of the TVCs and Gainclones. The amplifier sees a steady load through majority of the speaker's response with the BSC/ zobel in place. I referenced this from the response charts Mr.Brines sent me.