Amp/Preamp Asylum Looking for a new Amp or Preamp? If you're after tubes, post over here.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Amp/Preamp Asylum ]

---

[ Alert Moderator ]

---

RE: what is mono dual power supply in a preamp

Posted by Palustris (A) on July 7, 2016 at 15:33:57

In Reply to: RE: what is mono dual power supply in a preamp posted by Awe-d-o-file on July 7, 2016 at 13:06:57:

Thanks for your post; you clearly don't mind embarrassing yourself in public despite your overwhelming ignorance.

I stand by my statement that a dual mono supply in a preamp will be detrimental to the sound and, further, that the only reason for a marketing department to make such a statement is out of desperation to come up with something different. Having worked in both marketing and engineering I fully understand the pressure and the need to employ some means to differentiate a product from the competition. That's just the nature of the business.

That said, it just so happens that I have spent some time in the last few months actually testing different power supply configurations both dual mono and stereo for a preamplifier, DAC, or as the frontend for an amplifier. I built three power supplies; two mono and one stereo and I employed them in preamps and as the voltage stages of amplifiers. The supplies were architecturally the same: CLC with low reactance and low resistance parts; power transformers with abundant current capabilities; Wima DC Link capacitors exclusively; and a low reactance low resistance choke in the pi filter. The three power supplies have very low internal impedance and the same stable voltage output with ample current capabilities.

I employed my three power supplies using the same vacuum tube preamp stage and the same voltage amplifier in a power amp either as dual mono or as a stereo. While both mono and stereo supplies sounded truly excellent, extended listening with certain well recorded music revealed a slight difference between them. The stereo supply had an edge in coherence and a noticeably more stable and precise stereo image. This surprised me as I truly expected both the stereo and mono supplies to sound the same. As I have already stated, the three power supplies were identical with respect to architecture and components, the only difference was each will have had slightly different internal impedance and output voltage a result of standard deviation of the parts employed in the supplies.

If we abandon our preconceived notions and audiophool dogma and consider what might be happening, it becomes clear that slight changes in power supply voltage can manifest themselves in a tube amplification stage as slight differences in transconductance, plate resistance, and gain. This phenomenon is clearly shown in the tube manual. So, I believe what is happening is that despite the attempt to make the two mono supplies identical, it is impossible to make them entirely so since they are composed of two sets of transformers, capacitors, inductors and resistances. These slight changes manifest themselves, as I stated above as a slight blurring of the placement of instruments in the soundscape. They move slightly, blur, and are not as pinpoint accurate. The stereo supply does not suffer from the same defect because both stereo channels are fed off of the same supply: the voltage and internal impedance is identical for both channels.

So, Mr. Awedeophool, I challenge you to do your own testing; build your own power supplies; listen for changes in sound. Report back to us your findings. If you are fair-minded you will retract your characterization of me as a "fool" and apologize to the board for your ignorance.

This post is made possible by the generous support of people like you and our sponsors:

VH Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---