#21
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#22
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Here is an interesting test for a pre amp if you have an open reel tape deck with a variable output. Play the tape deck directly to the amplifier, then insert a pre amp between the tape deck and the amp. Listen to the loss of resolution that the pre amp will introduce. Compare 2 pre amps against each other in this capacity to see which one changes the sound of the tape deck least - that's the winner.
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#23
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I've thought about these issues as well and that's how I discovered the passive preamplifier I use in my system. Here is the principle behind its design: The unit's autoformers keep signal power (from the DAC) constant as the gain to the amp is attenuated. So as the voltage to drive the amps goes down, the current increases and this works to effectively lower the output impedance of the preamp to maintain the integrity of the low-level signal that drives the amplifiers. Most volume controls are resistive; when you turn down the volume a proportion of the voltage and current is thrown away along with dynamic contrasts. I wrote about it here. |
#24
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Nice write-up of the AVC-1 Carlos. I can attest in having visited your home that your system is transparent and beautiful sounding. The former having a lot to do with your passive preamp and the latter probably more because of the Pass amplifiers.
My DAC has a 69-bit digital volume control (implemented via FPGA I believe). I don't know how lossy it is when attenuating the signal (turning down the volume). Given the price of the AVC-1, especially when bought as a DIY kit, it's cheap enough I may buy it just to play with it. That said, it's some of the other properties/behaviors of a preamp I speak of in regard to musicality. Transparency is an interesting notion, with people defining it in a variety of ways. Is it emphasis on leading edge transients or tonality/bloom/body of what follows the onset of the note/sound one hears? Is it the reverb/echoes of the studio and concert hall? Is it the richness of timbre? For me it's a balance of all of the above. My new preamp gives me more information in terms of tonality and reverb. The more balanced sound with the active preamp can make the leading edge of notes sound not quite as accentuated, but that doesn't mean that audible information isn't there. It's just there is more of everything that follows that instance in time that is present to a greater degree. I find it interesting that a reputable and well-respected designer such as Bascom King say he can't definitively explain why his BHK components sound better with the preamp than without with his DAC driving his amps directly. Did he engineer it that way just to make more money? Maybe. But this phenomenon has been observed by more than one reviewer with various other brands. And I can state that I am certain I'm hearing more musical information in my recordings with my Rogue preamp than without, and likewise compared to my previous active linestage - the Classe CP-800. I'm also fairly sure it goes beyond impedance matching given my experience with the Placette even though I agree that is part of the equation of what a good preamp brings to the table. At the end of the day, I always believe there is a scientific explanation behind everything we experience. Sometimes science lags behind engineering (the Romans built bridges that have stood for 2 millennia long before equations were formulated that describes their ability to carry load). I think some day physicists and engineers will be able to explain why a Stradivarius sounds the way it does or why a preamplifier improves the sound of a stereo system. Until then, it's fun to debate and argue it out p.s. - I just checked Bent Audio's website and he's evidently been so busy with OEM work that he's not selling DIY or fully built units.
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Primary System (Always in flux): Analog Source: Rega RP10 Phono Preamp: Bryston BP2/PS3 Digital Software: Roon, Tidal Streaming Digital Music Server: Melco N1A/2 Digital Sources: Totaldac d1-twelve SE MkII (factory upgraded from MKI) with "live power" 4 output power supply, Oppo UDP-205 Preamplifier: Rogue Audio RP-9 (factory upgraded from RP-7) Amplifier: Vandersteen M5-HPA Speakers: Vandersteen Quatro Wood CT w/IsoAcoustics Gaia 1 feet Cabling: WW Platinum Starlight 7 digital wires, Totaldac Gigafilter USB filter, AQ Sky XLR, AQ Fire RCA Speaker Cables: AudioQuest Oak spades ---> bi-wire spades Power Cables: Esprit PC (for DAC), 2 WW Platinum Electra PC (Preamp/Phono Preamp), AQ NRG10 (Melco N1A/2), AQ Blizzard (Quatro Wood CT built-in subs) Power Conditioning: 2 AQ Niagara 1000, 3 Oyaide R1 outlets Sound Treatments: 23 ASC Tube Traps and 10 Panels Last edited by ylee; 10-21-2017 at 06:00 AM. |
#25
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Ayre has implemented one of the most interesting volume controls with the VGT.
It addresses one of the challenges an analog preamp has - that at low levels they lack dynamics and punch and life. From what I gather - the problem stems from using a variable resistor to control volume which has varying impedance presented. The difference is very clear to me in some of my combinations - a high gain EMM XDS1 player with a high gain Plinius SA Reference power amp makes my ARC Ref5SE quite unusable - pumping out almost full volume at less than 10 on the volume dial. Even with my PS Audio DS DAC, I’ve found a big improvement going to low gain on the DAC and using the Ref5SE at higher levels but maintaining the same SPL. Ayre uses a variable gain transistor which maintains the same impedance throughout. So I was really pleased with the BHK Signature Pre which uses tube gain and variable gain to achieve a similar result.
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AcousSignThunderTA5000PurpleHeartNS WandMasterPearwoodII PSA DSD BHK ThielCS3.7SS2.2 |
#26
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I noticed that John Chapman is no longer supporting the production of the AVC-1 because he's doing so much work for others. I think his main customer is Vinnie Rossi. I see a resemblance between this preamp and the the AVC-1. |
#27
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I appreciate the question was posed as the ‘sonic’ benefits of a PreAmp but it should be stated that switching sources is one of the most important functions of a PreAmp.
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Main Equipment: Kharma Elegance dB11-S, JL Audio F113v2 X 2, Block Audio Line & Mono SE Amplification, Bricasti M21 DAC, Antipodes Kala K-50 Server, Clearaudio Performance SE. Satisfy tonearm & Maestro Wood MM cartridge. Power: Shunyata Everest 8000, Sigma XC v2, Sigma NR v2, Block Audio PCs, Defender, ADDPowr Wizard Grounding: Shunyata Altaira CGS - 4 X Alpha CGS cables, Network : Supra Cat 8+, Twin (Nenon) Modified Buffalo GS2016 Switches, Keces P3 LPSU, Cables: Wireworld Platinum 8 USB, Wireworld Platinum Eclipse 8 Speaker cables, 6M & 1M Tubulus Concentus ICs, Other:Two PSI Audio AVAA C20, Multiple GIK products, Stillpoint Apertures, Stillpoint Minis and Ultra SS, Three 20 Amp lines, Furutech GTX - Gold outlets, Adona Rack |
#28
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Definitely. My acquiring a preamp was in part motivated by the desire to add a phono preamp in the future along with a turntable. Other digital sources of interest may be added too as the years ago by. I may also have my dad's reel-to-reel purchased in 1977 repaired so I can listen to it from time to time.
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Primary System (Always in flux): Analog Source: Rega RP10 Phono Preamp: Bryston BP2/PS3 Digital Software: Roon, Tidal Streaming Digital Music Server: Melco N1A/2 Digital Sources: Totaldac d1-twelve SE MkII (factory upgraded from MKI) with "live power" 4 output power supply, Oppo UDP-205 Preamplifier: Rogue Audio RP-9 (factory upgraded from RP-7) Amplifier: Vandersteen M5-HPA Speakers: Vandersteen Quatro Wood CT w/IsoAcoustics Gaia 1 feet Cabling: WW Platinum Starlight 7 digital wires, Totaldac Gigafilter USB filter, AQ Sky XLR, AQ Fire RCA Speaker Cables: AudioQuest Oak spades ---> bi-wire spades Power Cables: Esprit PC (for DAC), 2 WW Platinum Electra PC (Preamp/Phono Preamp), AQ NRG10 (Melco N1A/2), AQ Blizzard (Quatro Wood CT built-in subs) Power Conditioning: 2 AQ Niagara 1000, 3 Oyaide R1 outlets Sound Treatments: 23 ASC Tube Traps and 10 Panels |
#29
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I do believe you about the results of your comparisons, and it’s intriguing that we have had the opposite results. I bought my ML No. 523 for source switching and HT Bypass, the preference for its sound was unexpected. Last edited by Karl Maga; 10-23-2017 at 09:52 PM. |
#30
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1) not all digital gain stages are identical - some are better than others 2) the interface between gain stage, amplifier and speaker sensitivity needs to work. Generally going much below-18db or so can lead to enough digital loss that it may become an issue. 3) When I do these comparisons, I do not use multi miked, studio type recordings. If these are used, it becomes much more difficult to determine better versus preferences. I think this is a very big point - if I tried to make decisions on less than great recordings it becomes much more difficult or even can lead to different conclusions. Also, I don't generally agree that it all comes down to preference. Some things are simply better than others, and when talking about a pre amp - it is simply which one changes the sound of the source less. 4) The winner on what you would consider your best, most truthful recording is the winner. I listen for information retrieval, image specificity, volume of recorded venue and micro and macro dynamics. The winner on the very best minimally miked recordings is the winner - even if i prefer the alternative with different recordings. 5) I am listening solely for "truthfulness" to the source - not a preference. Of course, this is still to some degree subjective, but I have never had anyone else listening with me at the same time come to contrary conclusions - better is better - less is more.Generally, I find the elimination of the pre amp simply puts less between you and the music. Of course I know many others may not agree or have had the same experiences that I have had. If so, I would suggest listening or doing the comparison as highlighted above if you are interested - if not - no issues - we all need to be happy at the end of the day! |
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