using tube linestage before TVC

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1000a

using tube linestage before TVC
« on: 29 Apr 2009, 05:48 pm »
Hello Nick
or anyone who might be able to help,

I want to try placing my Monarchy MN24 tube line amp before my TVC, so the order would be (line amp - TVC - amp)
The reason is my tube line amp has too much gain used behind the TVC (with the line amp vol at full & even 3/4 the TVC vol at 1 clk late night listening is impossible).
Another reason is with the Line amp in position before the AMP, it picks up a lot of noise somehow- so I also thought the TVC in second position would also act as a better buffer.

Both the line amp and the TVC when used separately are dead silent as is the primary amp in integrated mode (has vol pot jumpers).

1-If I can do this, where do I set the volume (ideal) on the tube line amp?
2-Are the specs aligned enough (between the 2 units) to use them like this?

From Nick's website:  Maximum input Voltage of our TVC: All our TVC are tested in house at the voltage of 7.5vrms. They are design to take up to 20Vrms.

My line stage output specs are:

Output Impedance:
510 Ohm one pair RCA Tube Line Amp out,
Max Output 27 Vrms,
Output Impedance: 300 Ohm                   


Thanks in advance too anyone who might be able to help me.

1000a (ignore the below list- the new set up uses Virtue 1s (t-amp design) as monos

Say

  • Jr. Member
  • Posts: 64
Re: using tube linestage before TVC
« Reply #1 on: 29 Apr 2009, 08:52 pm »
Hello 100a, I tried a similar set up before and liked the results. I think you can get away with it by hooking up your source component to the Monarchy line level inputs, then another pair of interconnects to the TVC. If you can bypass the Monarchy's internal volume pot all the better. Experiment and see what you get (analog out versus line out). One way or another should cure your late nights blues thus having more range over your volume range .

hi5harry

Re: using tube linestage before TVC
« Reply #2 on: 29 Apr 2009, 09:18 pm »
I will  be anxious to see the replys. I am building a zero gain tube buffer circuit to use AFTER my Bent Audio TVC. I hope to impart a little tube magic into this system plus I have heard that if the TVC does not have to drive the interconect, you get a little more extended frequency response.
« Last Edit: 1 May 2009, 07:41 pm by hi5harry »

1000a

Re: using tube linestage before TVC
« Reply #3 on: 30 Apr 2009, 01:55 am »
I got a quick reply from CC Poon the designer of the Monarchy NM24 tube DAC / tube line amp on the same questions- I do not know if this helps others but I thought I should post it.  I will send him another email to make sure I have clarity on the last couple of questions. 
For now I will treat the NM24 at the vol pot location w some ERS paper place it back inline behind the TVC and ck it w vol set to full and 3/4 to see if ERS paper lowered noise.

Even if it does I will use a 12 position as a vol setting as he states below with the TVC in front of the line amp, this should rid most all the noise.  I am still hot to try the line amp to the TVC but a little paranoid from a past possible blunder.

Say: I am still concerned (line amp ---  TVC w the specs of a max 27 Vrms on the lineout going into a TVC which maxs out at 20 Vrms , but if I understand the TVC correctly the fiqure will not be an issue because the TVC reduces the impedance substantially, correct?

If you guys have seen the forum pages on the Promi tube stage w the TVC you know what I am after a little more drive with all that lovely TVC organic wide open detailed sound.   Despite the noise issue I was having the sound w the TVC and line amp together is definitely better than either used separately.

Hello Mr. Poon
 Sorry to bother you, a few questions.
 
context first:
I'm using my NM24 as a line amp behind a TVC so it's:     
digital source (feed thru NM24 tube DAC)-----TVC-----NM24 (as line amp)----amp
 
I'm setting the NM24 volume at full and also at 3 pm but both volumes are causing noise seemingly in the NM24 - easily heard in the speakers from a foot away at full vol. - with the TVC volume at zero.
 
There is no noise using either NM24 or TVC separately as pre-amps or the primary amp as an integrated (it's volume pot has jumpers to disable it).
 
The amp company did say I may get noise using a separate pre- so I am trying to do away with the noise and maximize the audio- the sound with the TVC and NM24 is out of this world good!
 
1-I am wondering what volume setting on the NM24 (w the NM24 after the TVC) you recommend using (the ideal in a perfect world) so I can adjust the volume with my TVC and still maximize the best audio quality?
Reply:
Say 12 o'clock

 
2-Would I lose any audio quality if I set the NM24 volume at 12 o'clock or lower?  (there is far less noise at that setting)
Reply:
No, actually the distortion would be lower at this setting, instead of at full volume.

 
3-Can the volume controll on my MN24 be disconnected - is this something I could do- or would I need you do do it?
Reply:
Not recommended: de-soldering necessary.

 
4-Can I use the NM24 as a line amp in front of the TVC? (I am hoping the TVC in the middle will better isolate the setup from noise)
so it would be:  digital source (as above)----NM24 (as line amp)----TVC---amp
Reply:
Our NM24 is hum free.
You can verify this by simlying bypassing the TVC as show in this signal chain.
 


5- If this is safe to do (it has been done this way with other preamps but the specs below worry me), what volume setting do you recommend on the NM24 when it's placed before the TVC?
Reply:
12 o'clock.

 
the specs on the TVC say: Maximum input Voltage of our TVC: All our TVC are tested in house at the voltage of 7.5vrms. They are design to take up to 20Vrms
NM24 specs say: Output Impedance: 510 Ohm one pair RCA Tube Line Amp out, Max Output 27 Vrms, Output Impedance: 300 Ohm
 
6- What worries me is their specs: They are design to take up to 20Vrms?, your max out is 27 Vrms?
 
Reply:
The volume control on the NM24 can adjust from Zero to Maximum.
I think 12 0'clock is a good starting point.

 
Thanks a million,
 
george

loxllxol

  • Jr. Member
  • Posts: 22
Re: using tube linestage before TVC
« Reply #4 on: 30 May 2009, 09:25 am »
I have the Monarchy as well and contemplating getting a promi TVC. Quick question, why are you bothering with the line amp? Can't you just go

source > dac (nm24) > TVC > amp? Only reason I could think of is a lack of system gain maybe?  Also, any updates to your situation?

PromitheusAudio

  • Jr. Member
  • Posts: 270
    • Promitheusaudio
Re: using tube linestage before TVC
« Reply #5 on: 1 Jun 2009, 03:19 pm »
 1000a
putting the tvc after the preamp is fine. Helps to lower the noise and lower the gain and impedance
the tvc can support the max output of your preamp. BUt then again it would not reach that high output voltage.

For the gain, that is a hard question. I think you can leave the tvc and the middle and the tube preamp middle. But this has to be played by ear



1000a

Re: using tube linestage before TVC
« Reply #6 on: 1 Jun 2009, 05:27 pm »
I have the Monarchy as well and contemplating getting a promi TVC. Quick question, why are you bothering with the line amp? Can't you just go

source > dac (nm24) > TVC > amp? Only reason I could think of is a lack of system gain maybe?  Also, any updates to your situation?

Short Version:

TVC alone= more organic, more detail, air, big stage :drool:
NM24 linestage= more drive to dynamics, more drive to PRAT :D

Many people bought a Promi active pre to use w their TVC and
were even more thrilled w their TVCs. It gave them back  :D :drool: :D the little
bit of drive they lost w their TVC.

Since I already owned the NM24 and Lynn Olson,s high praise for the linestage used with an auto former or a TVC it was a no brainer.

If I had to choose either or,. get the TVC- it is a no brainer- Fantastic would not change it for the world- I believe Nick still has some stock on sale no shipping.

IMS  I could use a little more gain w the TVC alone, with the linestage included I seemed to have too much gain- but Monarchy (CC Poon) told me to run the linestage at 1/2 vol. because running it at full the unit's distortion was at its highest.

So with Nick's recent comment and CC Poon's 

I am home free-now unfortunitly I need to fix a wire in my NM24.


Lynn Olson's comments:
Is there a weak point to the M24? Yes. It's the built-in volume control, which knocks down the quality of the linestage quite a bit. Thom and I were using the Dave Slagle autoformer volume control, which is in the same sonic league as the Bent Audio TX102 control, or other high-quality autoformer or transformer volume controls. If you just use the DAC portion of the M24, you'll never hear it. But if you listen to the linestage, which as mentioned above, is superb quality?the difference between the external autoformer volume control feeding the linestage, vs. the internal volume control?was the difference between a fairly decent $1000 tube linestage and a top-rank $10,000 tube linestage. Of course, what's a little unfair about this is autoformers or transformer volume controls usually cost as much as the entire M24!

1000a

Re: using tube linestage before TVC
« Reply #7 on: 1 Jun 2009, 05:35 pm »
Thanks Nick,

Now I can try both orientations and see which works best.
I am still absolutely blown away :drool: by your fantastic reasonably priced TVC.
It has allowed me to really achieve high end for reasonable money.

1000a

1000a
putting the tvc after the preamp is fine. Helps to lower the noise and lower the gain and impedance
the tvc can support the max output of your preamp. BUt then again it would not reach that high output voltage.

For the gain, that is a hard question. I think you can leave the tvc and the middle and the tube preamp middle. But this has to be played by ear