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E250: The Fosi Audio ZP3 Balanced Linestage
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E250: The Fosi Audio ZP3 Balanced Linestage

Introduction to Fozzy Audio Products

Overview of Previous Episodes

  • Greg Weaver introduces the audio analyst series, highlighting his positive experiences with Fozzy Audio products.
  • He mentions previous episodes (199, 206, and 209) where he examined the Fozzy Audio Balanced V3 monolock amplifiers and improvements made by replacing stock opamps.
  • Episode 245 focused on the $89 Q6 DAC, noting significant sonic enhancements after upgrading its opamp.

Exploring the Fozzy Audio ZP3 Preamplifier

Design and Features

  • The ZP3 is described as a well-built preamplifier that comes with a multi-functional remote control applicable across several products.
  • It features multiple connectivity options: two sets of RCA inputs, one XLR input, and various output jacks including subwoofer output.

User Interface

  • The front panel includes controls for power, input selection, balance, bass, treble adjustments, and a volume knob.
  • Unique sliding switches on the bottom panel allow users to bypass tone controls or select high-pass filter settings for low-frequency management.

High-Pass Filter Functionality

Frequency Management Options

  • The ZP3 offers three high-pass filter settings: allowing full spectrum audio or filtering out frequencies below 80 Hz or 120 Hz for subwoofer use.

Benefits of Filtering Low Frequencies

  • By directing low frequencies to a subwoofer output instead of main speakers, it prevents distortion from woofers attempting to reproduce inaudible frequencies.
  • This results in clearer bass response and improved overall sound quality by reducing mechanical distortions in speaker drivers.

Critiques of the ZP3 Preamplifier

Crossover Point Concerns

  • Weaver expresses concerns about high crossover points (80 Hz to 120 Hz), suggesting they encroach into mid-bass rather than focusing on true sub-bass frequencies.

Volume Control Issues

  • The volume knob's microprocessor-controlled rotary encoder does not synchronize with remote signals; thus users cannot visually confirm volume levels when adjusted remotely.

ZP3 Preamp Review: Performance Insights

Initial Setup and Configuration

  • The ZP3 preamp was installed in a secondary audio system, utilizing Rune for streaming from NAS or Cobuzz with the Whim Pro Plus.
  • It was paired with an upgraded Fozzy Audio Q6 DAC via coaxial output, driving Accora MRV1 monitors and powered subwoofers through a Y adapter.

Sound Quality Evaluation

  • The stock ZP3 preamp delivers engaging performance with quiet operation, clarity, detail, and refined resolution.
  • Spatial presentation is faithful left to right but somewhat shallow front to back; images are well represented with good location cues.
  • Despite a slightly dry presentation, the overall fidelity and articulation impressed the reviewer; it offers solid build quality at a judicious price.

Value Proposition

  • The ZP3 competes effectively against higher-priced preamps, offering more features than many competitors at its price point.
  • After six weeks of listening to the stock unit, curiosity led to exploring upgrades by substituting op amps for improved sonic performance.

Upgrade Process

  • Beginners are advised against DIY op amp swaps due to complexity; seeking professional help is recommended for upgrading the ZP3.
  • Detailed steps were taken to access and replace stock TI LME 49720 NA op amps with Sparkos Labs SS3602 discrete devices.

Performance Post-Upgrades

  • Installation of new op amps resulted in enhanced performance that exceeded expectations; improvements noted in tonal richness and dynamic expression.
  • Gains included better low-frequency definition, soundstage layering, and an authentic sense of space within recordings.
  • Overall bass performance improved significantly; dynamics became more nuanced while tone color displayed richer textures.

Conclusion on Upgraded Performance

  • The stock Fozzy Audio ZP3 provides excellent value as a foundational component in modest systems.
  • Upgrading with Sparkos Labs devices can lead to transformative experiences in sound quality that elevate system performance dramatically.

ZP3 Performance Review

Overview of the ZP3 Line Stage

  • The modded ZP3 line stage significantly outperformed a previous reference line stage, which had an original retail price of $1,250.
  • The upgraded ZP3 has brought the second space system closer to achieving world-class performance, comparable to the reference music system.
  • The ZP3 is noted for its exceptional design, build quality, and sonic performance—qualities that were not available just five years ago.
  • The speaker expresses gratitude for viewer support and encourages continued engagement with music through their channel and website.

Key Insights on Audio Equipment

  • The ZP3 exemplifies high value in audio equipment, showcasing advancements in technology and design that enhance overall listening experiences.
  • It joins other Fozzy Audio products that have received full endorsement from the speaker due to their superior performance and value.
Video description

0:00 Intro 0:18 Today's Topic: The Fosi Audio ZP3 0:28 Previous coverage 1:30 Getting acquainted with the ZP3 2:04 The rear 2:32 The front 3:06 The bottom 3:34 Tone control bypass 3:38 High Pass Filter 4:59 How the HPF works 6:41 Why I was underwhelmed 7:58 Remote volume and its considerations 8:35 The audition system 9:13 The stock system performance 11:09 Time to OpAmp roll 11:45 Not for the beginner 13:09 Discrete replacing semiconductor 13:21 My thanks to Andrew Sparks 13:45 The sound of the rolled OpAmps 15:40 The “stock” advantage 16:08 The rolled “gold” 16:40 The new reference for my Second Space 17:20 Enjoying a new golden age 17:45 Most enthusiastically recommended 17:56 Martini Time 18:24 Outro-Subscriptions Today, we are going to take a dive into the performance of the two-hundred-dollar Fosi Audio ZP3 balanced preamplifier, yet another well-built and overachieving device. And then, we will give it an upgrade, rolling out the OpAmps with the SparkoS Labs SS3602 discrete devices. Spoiler alert! BIG difference! Now, if you more advanced audio students are curious as to why I didn't dig into things like roll off, slopes, orders, and phase relationships in regard to the High Pass Filter used, there are two reasons. First, that information is not documented anywhere by Fosi, at least, that I have been able to locate. Further, I didn't think it made sense to dig into things like roll off, slopes, orders, and phase relationships for the high-pass filter, given my intended audience. However, since this episode has dropped, I have had that conversation on Facebook, so I’m reposting the relevant information here for those who choose to watch the episode to take in. My listening and playing with the ZP3 lead me to believe that the High Pass Filter has a very shallow curve, likely either a 6dB/octave slope, first-order crossover, or - more likely - a 12dB/octave slope, second-order crossover. My reasoning for that assumption is that it would make the most sense to use a second-order (12/dB per Octave) filter. As such, second-order filters exhibit a +180 degree phase shift in their stop band (at very low frequencies), relative to the input signal. With a +180° phase shift, merely inverting the signal's output restores phase coherence with the primary signal to avoid cancellation issues. And, at 12dB/Octave, as shallow as that is, it would be somewhere in the vicinity of about 10 dB down (half as loud) in the 40 to 50Hz range, so…that is the better choice of the two HPF options. Using the 80Hz selection, and applying the same assumptions about a second-order HPF, the resultant signal would be down 20ish dB or so (one quarter as loud) at the 40Hz-50Hz region. As such, it really doesn’t offer much value for its intended purpose to my way of thinking. Just my two-hundredths of a buck, here... 😀😄😇 LINKS ASSOCIATED WITH TODAY’S EPISODE The Fosi Audio ZP3 Preamplifier Website: https://fosiaudio.com/products/zp3-preamplifier Previous Second Space Fosi-based episodes: E199: The Amazing, Affordable Fosi Audio V3 Amplifiers https://youtu.be/sedOZWAdhIg E206: Epic Sonic Upgrade: The SparkoS Labs SS3602 Discreet Op Amp https://youtu.be/qRDnbXVsJ1o E209: The Fosi V3/SparkoS SS3602 Full Monty https://youtu.be/jpLtt3hJiCs E245: The Fosi Audio Q6 DAC Experience https://youtu.be/mslBc5pDFZE Ways to support the audio analyst©: Show your support with branded merchandise available from my Etsy Store! https://www.etsy.com/shop/TheAudioAnalyst Become a member - Patreon: https://www.patreon.com/theaudioanalyst One-time gift to “greg@theaudioanalyst.com” via PayPal One-Time Gift to “@theaudioanalyst” via Venmo Website: http://www.theaudioanalyst.com Facebook: https://www.facebook.com/theaudioanalyst X/Twitter: https://x.com/audioanalyst Instagram: https://www.instagram.com/audioanalyst/