[elmuncy]

First off, I love the sound of the Promitheus TVC.  It's better than anything I've ever had.

My problem, is I get far too much gain with my Sonographe A250 power amp.  One notch on the TVC and it's too loud for late night listening.  Being that this is a Passive pre, I never thought that I'd have this problem.  The Sonographe has an input impedence of 100k.

One of the ways I've tried to solve this, is by using line attenuators made by Rothman. It brings the volume down, and I thought the problem was solved, but the Rothmans change the sound, and not for the better.  I've tried them on the input and the output of the TVC, but they change the sound.

Has anyone else had this problem?  If so please help!

I

[bummrush]

Is this a common problem with that passive pre I had a 250, awhile back, i dont think the 100 k is unusual, but i suppose it could be.But with the passive isnt the situation you're in pretty odd?

[milpai]

Elmuncy,
Please check your connections. I think you may have mixed INPUT with OUTPUT and vice versa. Just a thought.

[onyxch]

What model of TVC are you using? I have a Ref4 TVC.
If you have a multimeter. Turn it to an 'ohm' mode then stick the two pins onto the + and - of the output RCA terminal(either right or left channel) of the TVC. Please record the ohm values of first 3 and the last 3 positions by turning the volume knob. The values on my Ref4 TVC are approximately: 1st =0.1 ohm
                                                                                                                      2nd = 0.6 ohm
                                                                                                                      3rd = 1.0 ohm
                                                                                                                     last = 118 ohm
If your values are too far away from mine. The TVC may be soldered in an opposite way as it should be.
Hope it helps.
David
                                                                                                     

[elmuncy]

My readings are as follows:

1  2.2
2  2.6
3  3.2

last  66

I think the main problem is that my digital sources put out too much gain, as I can play my phono pre-amp quite nicely.  Perhaps just attenuate the digital input.  I don't like doing that, because I can hear the difference.

[bummrush]

Whats the gain of your dig.I think alotof players put out like 1.9  to 2.5 ,,2.5 would be possibly high but doesnt seem that it would be too bad,but who knows.

[onyxch]

The data you provided seems fine . Any extra thing put between the CD player and the TVC will sure degrade the sound and will remove the merit of your TVC.

[elmuncy]

I've got several digital sources, and all of them do the same thing. I can tell from the ohm readings of my TVC, that it's higher than the other. Were these made, TVC's, with different levels of gain? I thought I read somewhere that the earlier ones had this problem, and that it was addressed. I bought the unit used, there is nothing on the unit, and I have no paperwork with it.

I switched the TVC with an older Modsquad passive, and the problem ended. All works fine with plenty of volume level.

I hesitate to purchas another TVC not being able to tell if it will work in my system. I really like the TVC

[milpai]

Hi Elmuncy,
Did you try to change the INPUT to OUPUT and OUTPUT to INPUT? I am specifying this even more, since you mention that you did not get any paperwork. The problem with this TVC is that INPUT and OUTPUTS are not properly marked. This TVC is damn good and I don't want you to loose heart till we have exhausted all options.
Good Luck

[onyxch]

Any chance that you may test your TVC in other stereo systems.

[PromitheusAudio]

First off i would like to thank to the various contributors who post helping to solve the solution

From i read, i can sumarize
1. You are using it correctly. If its in the wrong position, the sound would not be good
2. Attenuation levels are not enough for your system

If you can take a quick picture of the unit, or describe it to me i could tell you what is the gain attenutation

Currently we make all our tvc at -54dB as a standard unless requested. Previously around 2 years ago we were doing it with -48dB which we had feedbacks that it could not control the gain sufficiently. We also do custom attenutations of -60db to 72dB. Depending on the user's system. For instance a -60dB would be about 4th position of where you are now if its the new units. And it would be 7 position if you are using the -48dB. Which would be good match for easier control

TVC the reason they sound perceive louder because it represents an easier load to the cdp. With the current gain, this is more obvious they sound perceive louder than other passive devices

[elmuncy]

the unit is:  12" long
                   8" wide
metal top


Two knobs on front (left and right volume)
2 inputs   2 outputs and a switch on rear

[guest48077]

First off, I love the sound of the Promitheus TVC.  It's better than anything I've ever had.

My problem, is I get far too much gain with my Sonographe A250 power amp.  One notch on the TVC and it's too loud for late night listening.  Being that this is a Passive pre, I never thought that I'd have this problem.  The Sonographe has an input impedence of 100k.

One of the ways I've tried to solve this, is by using line attenuators made by Rothman. It brings the volume down, and I thought the problem was solved, but the Rothmans change the sound, and not for the better.  I've tried them on the input and the output of the TVC, but they change the sound.

Has anyone else had this problem?  If so please help!

I

I am using my Promitheus Dual Mono TVC with great succes. No gain issues. My amps are rated for
Input Impedance 10k ohms
Input Sensitivity 1 Vrms

With my Phono it is fine and with my CD player is is fine, and with my Computer Direct out (no DAC) it is also fine. Maybe this will help you with your Impedance numbers

[louie3]

I have another TVC.  It was made in the Far East also.   The back panel connections are backwards.   Input is output and Output is input.   I suspect their may be a language issue here.

Also the right and left channels are backwards (left says right and so forth).

Finally took the plunge and plugged it in backwards, sounds lovely....and I do mean freaking lovely!!!!

Louie3

[milpai]

Louie3,
That is what I am suggesting to the OP. Not sure if the OP tried this solution.

[elmuncy]

I have the TVC hooked up correctly.  I dragged out an old amp, Audiosource Amp 300, which has gain controls built in. I have to turn them almost all the way down to make things work. This TVC could work with someone that had more inefficient speakers, and a more inefficient amp.

[elmuncy]

Thanks for everyone that tried to help me. I found out from Nick that the TVC I have is an old one.  It would cost quite a bit to bring it up to modern.
What has solved the problem, is a variable output DAC.  I can turn it down enough to be able to play any of my digital sources. There doesn't seem to be any sound degradation like there was with the Rothwell attenuators. In case you're wondering which DAC, it's the Beresford 7520.