[gooberdude]

Subs work great with this TVC IMO.  The bass is thorough & forceful & musical. 

One user has commented that he no longer uses a sub in his set-up due to this attribute.

i demo'd a Hsu sub in my L/R recently.  I liked the sp level inputs best, but the RCA's had the same amount of signal driving the sub...sp level seemed to integrate better for me.  anti-cables have proven a good match for this duty.

aftermarket footers can change the bass performance of the TVC also.

[Steve Eddy]

In your design, would you say the 1:1 input transformers mostly contribute to the magic due to their impedance-matching ability, or their signal isolation ability, or both?

I ask because, the Promitheus TVC provides impedance-matching, but not signal isolation (I think)...

I think the term "impedance matching" is something of a misnomer here. Impedance matching generally means either a situation where the source and load impedances are the same, or the use of impedance transformation to increase the load impedance of a load that would otherwise excessively load down the source that's driving it.

At line levels, load impedances usually range from about 10k to 100k with some going as high as 1M. Even a 10k load isn't going to be a problem except perhaps for a handful of asthmatic tube output stages. So impedance matching in that sense isn't really of any benefit that I can see.

Also, the notion that a TVC increases the load impedance by the square of the turns ratio can be a bit misleading. While this would be the case with an ideal transformer, in a realworld transformer, the ability to increase the load impedance by the square of the turns ratio is limited by the transformer's primary inductance.

The transformer's primary inductance is effectively in parallel with the reflected load impedance. So unless you have a really high primary inductance (which would be infinite in an ideal transformer), the load impedance actually seen by the source that's driving the primary could be considerably less than the ideal reflected impedance.

So in some cases, at low frequencies, the source could be seeing a load impedance that's actually lower than it would see without the transformer.

Anyway, getting back to your question, I think the bulk of a good quality input transformer's "magic" comes from ground isolation and common-mode noise rejection. But I think there's also something else there that I can't quite put my finger on. I just know I like the results I get when using good quality input transformers.

se

[tanchiro58]

Subs work great with this TVC IMO.  The bass is thorough & forceful & musical. 

One user has commented that he no longer uses a sub in his set-up due to this attribute.

i demo'd a Hsu sub in my L/R recently.  I liked the sp level inputs best, but the RCA's had the same amount of signal driving the sub...sp level seemed to integrate better for me.  anti-cables have proven a good match for this duty.

aftermarket footers can change the bass performance of the TVC also.

In my system I have to use the Hsu sub which is connected to second RCA output (from low level input of sub) of the TVC since my SET parallel 2A3 (only 6-8 watts output) could not produce enough deep bass. However, the sub blends pretty well with my JBL D131 woofers. I have got a musical and articulate deep bass. I would like to know more about anticables. Do you know where can I find them? Thanks.

Tan

[gooberdude]

www.anticables.com    or work backwords through www.zeroimpedence.com

they are made by paul speltz.   In bulk, a pair cost $2.50 per foot.

I'm trying out the Hsu VTF-2, it is a monster!    Not sure if i'm going to keep it,
but playing with a sub has been fun.

[Early B.]

Keep it.

Hsu makes excellent musical subs for the money. The VTF-2/STF-2 is very nice.

[gooberdude]

I'm still on the fence....    I live in a condo with concrete subfloors & can't use the Hsu factory spikes, my neighbors below and to the sides feel the boom then.   So, i keep it on its side on top of an Auralex SubDude.    the SD is killer when you have suspended floors, its not so hot with thick carpet over concrete.

I might have bitten off more than i can chew in the VTF-2.   One of Hsu's smaller subs would probably do fine and i'd be able to spike it securely.  Lots of fun though!

[rollo]

Gooberdude,
                 Try this,raise your sub off the floor.It is recommended that the sub be raised 22% of your floor to ceiling height.Face the sub either rt or lft not facing you.Any boom or fuzzy base will go away.This was recommended by ASC Tube Trap Corp.
                  I built a MDF platform [2 layers 3/4"] resting on 4 cardboard tubes 4" in dia. sitting on a carpeted wood floor.Works great for me and all who have tried it.The key is getting the height of the sub [bottom] correct.just mulitiply your room height by 22% and thats the distance from the floor to the bottom of the driver.
       Have fun,sitting on top of your other sub is a start but maybe too high.
rollo

[PromitheusAudio]

can somebody explain this.  how do you classify the power energizer?                                                                                             
is the power energizer  A.  isolation transformer?
                                B.  power conditioner?
                                C.  power supply?

The power energizer should be classified as power conditioner. If you are looking for a isolation transformer we have our own Balance transformer
unit called Balanced Power Supply at
http://www.promitheusaudio.com/bps.html

Cheers hope this helps

Nicholas

[PromitheusAudio]

Nick --

Please tell us more about the upcoming DAC - is it SS or tube-based? Non-over sampling? What kind of op amps are used? Etc.?

Also, do you have a price range in mind yet that you can share?

On the upcoming DAC it would have
A) Non-oversampling using TDA1545
B) NIckel Core Pulse Transformer
C) Passive I/V with Allen Bradley Carbon Comp resistors
D) OP-Amp using Philips Ne5534 (most musical opamp i compared with)
E) Output transformer
F) 4 Separate Power SUpply for Receiver, DAC, Opamp + and - voltages
G) Low noise power transformer using our own balanced topology for noise cancelation.
We are trying to target the price range of around usd350 to 400
Future topology will be Tube output with output transformer. Without an output transformer whether tube or solidstate, to my ears the sound is no where near my analog rig.

Cheers
nicholas

[PromitheusAudio]

I'm still on the fence....    I live in a condo with concrete subfloors & can't use the Hsu factory spikes, my neighbors below and to the sides feel the boom then.   So, i keep it on its side on top of an Auralex SubDude.    the SD is killer when you have suspended floors, its not so hot with thick carpet over concrete.

I might have bitten off more than i can chew in the VTF-2.   One of Hsu's smaller subs would probably do fine and i'd be able to spike it securely.  Lots of fun though!

When using my sub i have some sound absorption material place on the floor. This help me to tighten up and made the sub more tuneful.
This absorption material is injected plastic with odd peaks and bottom to abosrb music. It works.

Also make somemore home brew bass traps. This really help to tune up the bass. Also even though silver some times get a bad rap for being thin sounding, i find them really good for bass duty. Firm, fast and texture. Plus being thin sounding helps with the BOOM.

[tanchiro58]

I'm still on the fence....    I live in a condo with concrete subfloors & can't use the Hsu factory spikes, my neighbors below and to the sides feel the boom then.   So, i keep it on its side on top of an Auralex SubDude.    the SD is killer when you have suspended floors, its not so hot with thick carpet over concrete.

I might have bitten off more than i can chew in the VTF-2.   One of Hsu's smaller subs would probably do fine and i'd be able to spike it securely.  Lots of fun though!

When using my sub i have some sound absorption material place on the floor. This help me to tighten up and made the sub more tuneful.
This absorption material is injected plastic with odd peaks and bottom to abosrb music. It works.

Also make somemore home brew bass traps. This really help to tune up the bass. Also even though silver some times get a bad rap for being thin sounding, i find them really good for bass duty. Firm, fast and texture. Plus being thin sounding helps with the BOOM.

I put my Hsu sub on a Maple wood platform and it sounds without boomy but having deep bass too. However, if you place your sub at a one of the corner of the room you should place a bass trap at that corner so the sound would not effect to your listening and/or other room behind the wall.
I will try your method Nick. Thanks.

Regards,
Tan

[gooberdude]

based on the advice of a poster here, Tanchiro, i mounted the sub on a 2" thick 15' x 18' Timbernation platform, it sounds much better than having the sub lay sideways on the SubDude.  More tuneful and tight output....this is gonna cost me another $100      The sub is facing the ground with the factory spikes into the platform.     I will try laying it on the side on top of the platform to see if firing left or right is beneficial...its cool that the sub sounds good when its spiked though.    

I also removed the Dayton brass spikes from my amp's maple timbernation platform (floor mounted) last night, so now the amp is coupled to the platform via Mapleshade footers and the plat simply sits on the carpet - isolated from the concrete subfloor.   Concrete sounds terrible!   there's a new tone to the sound now, should be interesting after its settled for a day.  my immediate reaction was that the sound is sweeter.

A few weeks back i realized how bad my speakers sounded when spiked to concrete - it was immediately obvious with the sub - and now with my amp.    i may  even remove the floor spikes on the equip rack as well.  just can't get over concrete's bad effects...

Rollo, according to your calculations the woofer needs to be about 21" off the ground in my L/R.  I have 8' tall ceilings (96" x 22% = 21.12).  Is this correct?
If the sub is sitting on its side, should the bottom of the woofer be 21" up from the floor??    i could do this easily with the sub upside down and sitting on a 2" platform...the driver would be firing at the ceiling though.

I just ordered a sub interconnect from Blue jeans cable. in a week i hope to try the sub with the IC input versus sp level with the anti-cables.  The only IC i've tried so far is a Heartland cable with Eichmann's, not a good match.  that IC is SO slow sounding...  the anti-cables seem to do great on the sp level input.    


Over the past 2 weeks i've been demo'ing two separate sets of 4" thick Mapleshade speaker stands...the Ultra bedrocks & the floorstanding speaker plinths.   I'm finding the Ultra Bedrocks to work best with my floorstanders - this is NOT what they were designed for.  

After removing the brass feet from the speaker plinths I now have 2 - 4" thick Mapleshade 12" x 15" platforms to play with.    i've swapped back & forth between the MS & Timbernation plats under the TT, not yet with the TVC though.  

There's very little comparison between the 2 brands.  The MS 4" is simply 3-D.  it opens a deep, clear and wide window into recordings.  the Timbernation is quite 2-D in comparison, sounds WAY less refined.    I'm probably doing more harm then good since i'll never own the 4" MS platforms, but it is very interesting to hear the diffs between the wood.   Its as big an effect as when i inserted the Belles 150A Hot Rod in my system versus the old Muse 100.   The Muse is warm, fuzzy and bass heavy whereas the Belles is open, airy, 3-D and really precise yet far from dry or analytical.  Slow vs fast with both being musical...  

I fully believe the TT is more receptive to the platforms than the TVC...


nick, what inputs will your DAC have?  USB?    And how is the Hybrid amp devlopment going?

[rollo]

Gooberdude,
                Your math is correct.When I had a downfiring sub and turned it on its side there was just no going back.I forgot to add before the sub will require some weight on top,seems to stabilize the cab. vibes.
         My sub is located approx. 4 feet behind the pipedreams and 2 feetlft. of the right speaker.NO CORNER location for me.
        As we all know low bass needs some distance [length] to fully develope,say 40 ft.If you fire your sub into the floor you defeat the theory.I tried to position the sub where it would reflect the sound wave to achieve a sound wave as long as possible.NO BOOM,at all.I run the pipes full range[60HZ flat] and tune the sub to 65HZ,blends well for my rig.
        TRy it and put on some serious bass material you will be suprised!
rollo

[gooberdude]

i will certianly try that Rollo.   I have a spare pointed small brass weight from mapleshade and will try that on the side to deal with vibes.   

My room won't allow a corner position.   Now the sub is behind the speaks 3' and closer to the left one.  Its about 2' from the front wall.     I'm running my speaks full-range too with the hsu x-over at just under 60hz...haven't played with that setting much though.   Experimenting with difft speaker stands keeps changing the amount of low bass the Thiels put out. Once i get the stands figured out i'll really dial in the sub.

The sub is a whole new experience.  Lots of deep bass in recordings that wasn't audible before.
I fought tooth & nail to keep my system simple with only 2 speakers, glad i took the plunge though.

Old recordings are the most surprising...the bass guitar in Beatles albums is simply awesome on some tracks.

[StereoJoe]

Finally, my TVC showed up today! Strange feeling to see and handle it after just seeing pictures. I've plugged it into my system and played a few hours: there is a fullness and kind of ease with the way it delivers music - very enjoyable! Dynamics are good, the background is dead silent. The bass has not settled yet, guess it takes some time to fully get on track.
However, there is a slight problem: at lowest level on the volume control, the sound is still too loud for late night and easy listening. I need to figure a way around this, any hint or tips?


Regards,

[gooberdude]

I think the TVC needs a month to settle in order to fix the click #1 problem...i recall thinking the same as you initially.

it could be a gain or impedence issue too.     

Mine is a few months old now and i don't notice the 'instant sound' being a problem anymore.    however there is still sound at click 1, which is something no other pre i've owned did.

Over the next month the presentation should get real smoooooth almost to where the term 'effortless' is an understatement.

matt

[vkaiwar]

I've had a Promitheus TVC Ref 2 for about a month now.  This is definitely the best preamp I've owned and it's a great credit to Nicholas for providing such a fine unit at a decent price.  The other day I was running the unit through its paces and decided to turn the volume control all the way to the maximum position (with the music off).  Once I got past the 3 o'clock position each click was accompanied by a sharp burst of noise.  This happened whether I was turning it up or down.  Up to the 3 o'clock things are fine.  I have an email in to Nicholas and I'm awaiting his response, but I was wondering if anyone else has had this problem, and also what might be the cause of it.

Cheers.

[tanchiro58]

Mine is an Dual Mono TVC old version with one aluminum plate on top and wooden attenuators but it does not have any problems except when I turn volume up the step has a big gap (23 steps) the music is stopped for a few seconds (not continuously). In my opinion the sound of this version has more spacious, smoother and musical than a stereo version (sold to my friend) that has aluminum plates on top and bottom with input switch and stereo volume knobs in the front.

Regards,
Tan

[F-100]

Mine is an Dual Mono TVC old version with one aluminum plate on top and wooden attenuators but it does not have any problems except when I turn volume up the step has a big gap (23 steps) the music is stopped for a few seconds (not continuously). In my opinion the sound of this version has more spacious, smoother and musical than a stereo version (sold to my friend) that has aluminum plates on top and bottom with input switch and stereo volume knobs in the front.

Regards,
Tan

Tan, thanks for introducing me to the preamp . When Tan told me about this unit, I thought to myself that this is just "another preamp" and there is no way it can sound better than my Blue Circle BC3, which cost almost ten times more in MSRP. Well, I was dead wrong... I was blown away by the sound of this little preamp. As other owners had stated, the Promitheous has more depth and width, and the soundstaging is amazing.

The Promitheous is definitely one of the hidden gems in the audio industry and I'm going to keep this baby.   

[Gaara]

Tan,

Did you purchase your dual mono tvc straight from Nic or from audiogon?  You mentioned earlier that you bought one off audiogon, but I wasn't sure if it was your stereo one or your mono.  I purchased one off audiogon from Gvcycleman, at the time he was selling two dinged up dual monos, a light one and a dark one.  Just wondering because mine does not have 24 steps, it is only 16 steps + mute with -32db of attenuation.

Jared