Jump to content

In a digital system how important it an analogue preamp?


DomT
 Share

Recommended Posts

2 minutes ago, TheFlash said:

Adding a preamp into a chain which previously had none simply cannot let more of the original signal through. No additional component can do this.

Isn't it about replacing one component for another? 

I think I might have lost the plot on this. :D

Link to comment
Share on other sites

Most active pre’s add their flavour. None can let through more than a TVC passive pre.
Oh dear, I'm afraid this is just absolutely not true.

While many would love to believe that TVCs are the perfect weapon, they are not.

As you can see in the picture below, the TVC being measured here actually exhibits quite monumental HF roll off within the audible range. TVCs also are totally susceptible to hum and airborne RF. They also introduce inductance and are very easy to achieve mismatched impedance with.

I am not knocking anyone for using one, or criticizing TVCs, I hear the appeal, but they are not as linear as well designed solid state preamps, and almost all of them cant achieve anywhere near the same bandwidth.

The same issues exist with SUTS, which is why I abandoned those too.

I have a active (unity gain buffer) preamp here that has the following spec:

Frequency Response: D.C. – >500kHz
THD: S+N/N Ratio: >108dB (IEC ‘A’)
Crosstalk: >90dB (10Hz – 20kHz)
60ffc83d31c6add896c0a7084b7fa325.jpg

Sent from my KB2003 using Tapatalk



  • Upvote 3
Link to comment
Share on other sites

HF rolloff. That's absolutely what I hear with all the TVC preamps I've tried. Boring! 

EDIT - I should have mentioned the HF rolloff thing previously, but Oli's post brought to mind the full horror of the TVC preamps I tried! I grew to really dislike them. 

Edited by JANDL100
Link to comment
Share on other sites

3 minutes ago, Bigman80 said:

Oh dear, I'm afraid this is just absolutely not true.

While many would love to believe that TVCs are the perfect weapon, they are not.

As you can see in the picture below, the TVC being measured here actually exhibits quite monumental HF roll off within the audible range. TVCs also are totally susceptible to hum and airborne RF. They also introduce inductance and are very easy to achieve mismatched impedance with.

I am not knocking anyone for using one, or criticizing TVCs, I hear the appeal, but they are not as linear as well designed solid state preamps, and almost all of them cant achieve anywhere near the same bandwidth.

The same issues exist with SUTS, which is why I abandoned those too.

I have a active (unity gain buffer) preamp here that has the following spec:

Frequency Response: D.C. – >500kHz
THD: S+N/N Ratio: >108dB (IEC ‘A’)
Crosstalk: >90dB (10Hz – 20kHz)
60ffc83d31c6add896c0a7084b7fa325.jpg

Sent from my KB2003 using Tapatalk


 

Perhaps I should have said MFA TVC. 

Which TVC were you using when you saw HF rolloff?

Link to comment
Share on other sites







Perhaps I should have said MFA TVC. 

Which TVC were you using when you saw HF rolloff?


We have measured around 11 TVCs, the best in terms of bandwidth being a pair of Tribute Silver wound TVCs, that includes Sowter made TVC. Also, don't be fooled...they all sounded different, thus imparting their own sound on the signal.

Same with the SUTS I tried. Ortofons, Hashimotos, Bobs devices.....you name them!

However, all of the other issues remain. Including bandwidth and linearity issues.

Regardless of who makes them and what they cost.

Just to add, I used a Slagle for months and it was beautiful. I still miss it at times, but that had a definite character too. Mainly in the LF which was not what I would describe as "measuring acceptably"


Sent from my KB2003 using Tapatalk





  • Like 1
  • Upvote 1
Link to comment
Share on other sites

My Slagle:189b48ad1d8b7b4b12058444ddffb9f8.jpgd8226a208d235e8c52eb456f1a315211.jpg

Sent from my KB2003 using Tapatalk

Link to comment
Share on other sites

48 minutes ago, TheFlash said:

It simply can’t.

Following your train of thought ......

Since i hear a more dynamic sound using a preamp compared to using the output stage in the DAC then if the preamp can't add the dynamics then the volume control / Output stage in the DAC's must be squashing the dynamics instead. An equally unpalatable suggestion to some i'm sure

maybe the impedence matching aspect is important here ?

  • Upvote 1
Link to comment
Share on other sites

13 minutes ago, Bigman80 said:



 


I have measured around 11 TVCs, the best in terms of bandwidth being a pair of Tribute Silver wound TVCs, that includes Sowter made TVC. Also, don't be fooled...they all sounded different, thus imparting their own sound on the signal. Same with the SUTS I tried. Ortofons, Hashimotos, Bobs devices.....you name them!

However, all of the other issues remain. Including bandwidth and linearity issues.

Regardless of who makes them and what they cost.

Just to add, I used a Slagle for months and it was beautiful. I still miss it at times, but that had a definite character too.


Sent from my KB2003 using Tapatalk

 

You invested in a load of measuring gear, Oliver? When did that happen?

Link to comment
Share on other sites

Following your train of thought ......
Since i hear a more dynamic sound using a preamp compared to using the output stage in the DAC then if the preamp can't add the dynamics then the volume control / Output stage in the DAC's must be squashing the dynamics instead. An equally unpalatable suggestion to some i'm sure
maybe the impedence matching aspect is important here ?
Your preamp likely has gain, whereas most DAC based Volume controls don't.

This may explain the new found dynamism.



Sent from my KB2003 using Tapatalk

  • Upvote 2
Link to comment
Share on other sites

You invested in a load of measuring gear, Oliver? When did that happen?
When I stared to build phonostages, Paul.

Also, since 2016 ive take nearly everything that crosses my path to@Firebottle where we run the rule over the equipment. It's been very illuminating.

In recent times I've also gained access to more equipment and expertise from another UK hifi designer who has taught me a great deal.

Want to see my oscilloscope? It's a 16bit digital jobbie....very useful.

Sent from my KB2003 using Tapatalk


Link to comment
Share on other sites

to quote the our now absent friend......."level matched" !

i feel like an actor saying "Macbeth" now  

Edited by mtbmarkymark
  • Haha 2
Link to comment
Share on other sites

to quote the our now absent friend......."level matched" !
I have a preamp that I can change the gain with. Nothing else changes, except for one resistor being added to the circuit.

When I added gain, it created an emphasis on the leading edge and made the bass appear to hit harder.

I went from a factor of 2 to 8 and it seemed to change more per addition. I prefer the gain factor of 0, and have stayed there.

Gain. It has an effect.

Sent from my KB2003 using Tapatalk

  • Like 2
  • Upvote 1
Link to comment
Share on other sites

frantically rushes off to research the difference between gain and level......

Edited by mtbmarkymark
Link to comment
Share on other sites

3 minutes ago, Bigman80 said:

Want to see my oscilloscope?

I think I saw that on a business card pinned to a red telephone box, in Soho, in about 1979. 

I'm pleased you're enjoying your hi-fi journey. Just be careful where you point that thing...

  • Like 1
  • Haha 3
Link to comment
Share on other sites

I think I saw that on a business card pinned to a red telephone box, in Soho, in about 1979. 
I'm pleased you're enjoying your hi-fi journey. Just be careful where you point that thing...
Hahaha, nothing says "I love this hobby" like a probe in dangerous places......that's what I tell the wife anyway.

Sent from my KB2003 using Tapatalk

  • Like 1
  • Haha 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...