Promitheus TVC passive preamp anyone?

rollo · « **Reply #2000 on:** 19 Jul 2007, 01:08 pm »

Quote from: Gpj on 19 Jul 2007, 02:31 am

Hello all. A summary: I rec'd my first TVC, standard edition in Five, yes 5, days. Replaced a very well made 36 step dual mono stepped attenuator w hand matched resistors and star grounding that I had used for 15 years. The improvement was obvious. Much smoother, greater depth, sweeter. rather like replacing a good ceramic plate RCA 211 with mother's best Western Electric metal plate. Smile and relax into the music. After 20 or so hours of break in (400hrs, you guys are kidding right?) disaster. A loud hum in the right channel. After switching and reswitching tubes to try to isolate the problem I tried inputting a signal and..aaargh... full output to that channel. No attenuation. Scary loud. Luckily my Quads were retired and there was no damage to the Dynaudios. The unbreakable TVC was broken.I got to Nick and he offered to send a replacement. I accepted but upgraded to a dual mono single box ref3 that was available. While waiting for my replacement TVC I returned the attenuator to the system. The sound that had brought me so much pleasure for so many years was now unlistenable. Once you hear a distortion it is impossible to tune it out. I waited. Turn around was again again five days. For those concerned about delay I had received two consecutive orders in 10 days! The ref3 is marvelous. Both units sound/sounded so organic and musical that I cannot imagine anyone not being delighted with either, regardless the level of his system. Props to Nicholas and the crew (?) at Promitheus. I will try later to discuss the minute differences between the two units. I will continue to burn the new one in past the current 120 hrs although I am not a true believer. Gotta go for now. I can hear Holly Cole in my listening room again. Damn! I told her to stop stalking me.....Gerry

Five days, where are you located?

rollo

Gpj · « **Reply #2001 on:** 19 Jul 2007, 02:57 pm »

Quote from: NewBuyer on 19 Jul 2007, 05:58 am

Quote from: Gpj on 19 Jul 2007, 02:31 am
...After 20 or so hours of break in (400hrs, you guys are kidding right?) disaster. A loud hum in the right channel. After switching and reswitching tubes to try to isolate the problem I tried inputting a signal and..aaargh... full output to that channel. No attenuation. Scary loud. Luckily my Quads were retired and there was no damage to the Dynaudios. The unbreakable TVC was broken...

Hey Gerry did you ever determine what specifically broke in your TVC? Hello NB In discussion w Nick, it appears to have been a delayed reaction to shipping trauma. I personally do not know if the problem is in the trans or the switch. I have forwarded the unit to a USA address and at some point a determination can be made. A minor inconvenience at best Gerry

Gpj · « **Reply #2002 on:** 19 Jul 2007, 03:00 pm »

[/quote]

Five days, where are you located?

rollo
[/quote] I'm in NY on LI Rollo

Jos · « **Reply #2003 on:** 19 Jul 2007, 11:20 pm »

Hi guys,
I'm from the Netherlands and just ordered my TVC ( dual mono ref.) for a try out period. I play with a 0.5 mV cart and a phono stage that can deliver 70 dB, so I'm curious to see whether this will work.
Nick thought it would be OK.

Currently I use a tube pre but that gives so much gain that I can hardly use the volume control and that's why I started looking for a passive. I really hope this will work so that I can relax and simply enjoy the music.

I'll try to add a picture of my system so that you can see where the Promi is going to end up.

Cheers,

Jos

Jos · « **Reply #2004 on:** 19 Jul 2007, 11:29 pm »

One more picture of my amps.

Jos

Jos · « **Reply #2005 on:** 19 Jul 2007, 11:31 pm »

I'm so happy the pictures work that I'll add one more of my pre.

GHM · « **Reply #2006 on:** 19 Jul 2007, 11:54 pm »

Jos you have some beautiful equipment there! Very nice indeed! aa What are those speakers?
You're quick with that camera..you caught a fly relaxing on the preamp.

1000a · « **Reply #2007 on:** 20 Jul 2007, 12:10 am »

Quote from: GHM on 19 Jul 2007, 11:54 pm

Jos you have some beautiful equipment there! Very nice indeed! aa What are those speakers?
You're quick with that camera..you caught a fly relaxing on the preamp.

killing me

JoshK · « **Reply #2008 on:** 20 Jul 2007, 12:18 am »

I am assuming the 1st is your speakers, the 2nd your amp and the 3rd your preamp?? If that is pushpull transmitter with 100+db speakers, no wonder you have too much gain! The only reason why the TVC wouldn't work in this case is too long of cables or a pathetic output impedance (~drive capability) of your source.

If you really wanted to keep your current equiptment and the TVC doesn't work for you, you can use a step down output transformer on your preamp. This will lower the gain of your preamp and lower the output impedance (Zout, which makes its drive capability go up) as well.

JoshK · « **Reply #2009 on:** 20 Jul 2007, 12:20 am »

btw, love the fly!

tanchiro58 · « **Reply #2010 on:** 20 Jul 2007, 12:42 am »

Jos,

Can I copy the picture of your preamp and THE FLY? Honestly where did you get the wooden horn? Do you have JBL LE 85 or 175 alnico magnets? What kind of woofers and tweeters are you using?

Tan

rollo · « **Reply #2011 on:** 20 Jul 2007, 12:50 am »

Quote from: JoshK on 20 Jul 2007, 12:18 am

I am assuming the 1st is your speakers, the 2nd your amp and the 3rd your preamp?? If that is pushpull transmitter with 100+db speakers, no wonder you have too much gain! The only reason why the TVC wouldn't work in this case is too long of cables or a pathetic output impedance (~drive capability) of your source.

If you really wanted to keep your current equipment and the TVC doesn't work for you, you can use a step down output transformer on your preamp. This will lower the gain of your preamp and lower the output impedance (Zout, which makes its drive capability go up) as well.

Josh K,
The TVC has no problems with long IC's. I use 5 Mtrs and it has been tested using 7.5 Mtrs no problem. If the passive was resistive based I would then agree. The Transformers take care of that.

Jos,

That is one hell of a preamp. I am back to using my active I miss the clarity of the Dual Mono dual box TVC but the weight, authority, depth and scale is now back in my system. I will give the TVC a fair shake and compare one more time. Both have their advantages and disadvantages as you will find out.

rollo

rollo · « **Reply #2012 on:** 20 Jul 2007, 12:52 am »

Quote from: Gpj on 19 Jul 2007, 03:00 pm

Five days, where are you located?

rollo
[/quote] I'm in NY on LI Rollo
[/quote]

So am I. If you want to come over for a listen email me. Good luck with your TVC.

rollo

JoshK · « **Reply #2013 on:** 20 Jul 2007, 12:59 am »

Quote from: rollo on 20 Jul 2007, 12:50 am

Josh K,
The TVC has no problems with long IC's. I use 5 Mtrs and it has been tested using 7.5 Mtrs no problem. If the passive was resistive based I would then agree. The Transformers take care of that.

Depends on the capacitance of your IC's...but anyway, i agree that the TVC does better than passive (increased current).

Gpj · « **Reply #2014 on:** 20 Jul 2007, 01:48 am »

Quote from: rollo on 20 Jul 2007, 12:52 am

Quote from: Gpj on 19 Jul 2007, 03:00 pm

Re: Email me

rollo I would like to get together. I confess to not being very good with these messageboards. I believe I have sent you a PM

Gpj · « **Reply #2015 on:** 20 Jul 2007, 01:54 am »

One more picture of my amps.

Jos

Very nice Jos. Should you have an interest in NOS RCA or United Electronics 211's let me know Gerry

Jos · « **Reply #2016 on:** 20 Jul 2007, 09:15 am »

Josh,

Never thought of using a step down transformer. Good idea. That might be the way to go if the TVC doesn't work for me.

The speakers consist of the following components:

B&C DE 25-16 tweeters.
Iwata Horns with Philips EL 5502 Drivers
Altec Lansing 515C bas units in Onken Grand enclosures.
Sensitivity: 98dB.

Tachiro, I bought them from a German Herr Doctor who had them handmade in Italy. Cost him a fortune but he simply wanted a change after living with them for a few years. I'll post a picture of the crossovers
They gave me a shock when I first saw them; the size of beercrates and I'm not talking sixpacks.

The power amps are 90 Watt set using parallel 845's.

I kind of like the fly myself, gives it all a 'human'touch.

Rollo, wouldn't it be possible to use the TVC with my pre amp, or is that putting the horse behind the cart?

Jos

PromitheusAudio · « **Reply #2017 on:** 20 Jul 2007, 10:59 am »

You can actually use the TVC infront of your preamp. Many people have done this and they like the results
or you can try to remove the volume control and use the TVC as the volume control
You get best of both worlds

F-100 · « **Reply #2018 on:** 20 Jul 2007, 01:17 pm »

Holly Smoke!!! That is some killer xover . This is the first time that I've seen Xover using tube components.
Very nice system you got there, Jos.

Gpj · « **Reply #2019 on:** 20 Jul 2007, 02:54 pm »

PS: I am not a tweaker by nature. My feeling is that you do not change the signature of the unit and if you are spending too much time tweaking and too little listening to music there is a problem. However

in my setup the wooden feet Nick provides deadened the sound points-down and left the TVC to slip and slide points- up. My solution? Those of you who have dining room chairs on wooden floors are familiar with the stick on sliders that attach to the bottom of the chair legs. The ones I have are thick felt. I doubled up three pairs (single one is not high enough to clear tranny screws on bottom of unit) and stuck them on, two in front, one in rear. Voila. Just the right height, dampens the base plate (more than three feet sounded overdamped), and TVC does not slide around. Bass seems right and midrange is sparkling. They are cheap and come off with a little tugging. Works for me. Gerry