• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Tone controls in tube setup

grindfix

grindfix

Full time hobby
Subscriber
My current system is all SS and I tend to shape the sound a little depending on the recording. I understand that vacuum tube sound is different and possibly all intended frequencies are coming through better at lower volumes then in SS setup, but what about room acoustics or if amp to speakers match is not optimal?
Why better preamps do not come with tone controls? I want to try and build VTA's (tubes4hifi) SP12, PH14 and ST120 to run with my stacked OLA speakers. Sources would be Teac UD-301 DAC and Dennon DP-51F with DL300/AU320 SUT. What are the chances that I'd need to trim some frequencies?
Thanks
 
Register to hide this ad
Hi end tubed preamps did away, mostly, with tone controls. Tone controls by their nature can introduce signal degradation and coloration. I am not familiar with the current tube preamps available so, vintage units are the most available with tone controls. The Dynaco PAS preamp is probably the tubed preamp with tone controls that was produced in the greatest numbers. And because of that it is one of the most reasonably priced. With Hi end units dealers want to sell you "room treatments" to cancel or ameliorate any in room problems.
 
grindfix said:
My current system is all SS and I tend to shape the sound a little depending on the recording. I understand that vacuum tube sound is different and possibly all intended frequencies are coming through better at lower volumes then in SS setup, but what about room acoustics or if amp to speakers match is not optimal?
Why better preamps do not come with tone controls? I want to try and build VTA's (tubes4hifi) SP12, PH14 and ST120 to run with my stacked OLA speakers. Sources would be Teac UD-301 DAC and Dennon DP-51F with DL300/AU320 SUT. What are the chances that I'd need to trim some frequencies?
Thanks
Click to expand...

If you use tone controls now I think the odds are good you'll still want to use them with tube gear.
 
Unless all of your recordings are perfect and the speakers are linear chances are that
having tonecontrol will enhance your music experience.
To be able to defeat them is certenly a plus, just like dynaco pas3X.
 
All my vintage gear has tone controls including a Mac 110, I have one modern tube pre that has no tone controls and I like it very much, I also very much like my vintage gear with my 110 sounding just as good as my modern pre, though my modern pre has a bit more detail but that doesn’t make my Mac any less of a quality piece.
 
peterh said:
Unless all of your recordings are perfect and the speakers are linear chances are that
having tonecontrol will enhance your music experience.
To be able to defeat them is certenly a plus, just like dynaco pas3X.
Click to expand...
Hi Peter, on the PAS, the tone controls are not "defeated" which implies that they are out of circuit, but supposedly at the "flat" setting. But one must be sure that the pot is properly positioned for that to be true and also that the original PAS pot is being used. With that preamp passing from one owner to another sometimes changes are made that are undocumented and parts that are not original are used. The Sansui AU70 is one amp in which there is a switch that actual reroutes the signal from the tone controls to the tubes and thereby defeating that circuit. I am sure there are other amps or preamps with that circuit, but they are somewhat rare.
 
primosounds said:
Hi Peter, on the PAS, the tone controls are not "defeated" which implies that they are out of circuit, but supposedly at the "flat" setting. But one must be sure that the pot is properly positioned for that to be true and also that the original PAS pot is being used. With that preamp passing from one owner to another sometimes changes are made that are undocumented and parts that are not original are used. The Sansui AU70 is one amp in which there is a switch that actual reroutes the signal from the tone controls to the tubes and thereby defeating that circuit. I am sure there are other amps or preamps with that circuit, but they are somewhat rare.
Click to expand...

That is true for the PAS 2/3, however, Peter was referring to the PAS 3X. In this case the tone controls are, in fact, out of circuit when set to the flat setting. They are completely bypassed.
 
primosounds said:
Hi Peter, on the PAS, the tone controls are not "defeated" which implies that they are out of circuit, but supposedly at the "flat" setting. But one must be sure that the pot is properly positioned for that to be true and also that the original PAS pot is being used. With that preamp passing from one owner to another sometimes changes are made that are undocumented and parts that are not original are used. The Sansui AU70 is one amp in which there is a switch that actual reroutes the signal from the tone controls to the tubes and thereby defeating that circuit. I am sure there are other amps or preamps with that circuit, but they are somewhat rare.
Click to expand...
Undocumented changes will nullify any claim of accuracy and sound quality. We are discussing "original" amps.

Another interesting amp is dynaco pas-4, that lacked tonecontrol but had a loop for an external tonecontrol. Defeat was made by
deselecting the loop. It's an interesting idea as the tonecontrol is independent and may be of any complexity and with any
bells and whistles. Unfortently the only exemples of such tonecontrols are equalizers, as far as i know.
 
You must log in or register to reply here.
Back
Top Bottom