It came today and is now in (actually outside) my rack. I realize that it needs to burn-in. So we'll see if I can update my wrong opinions on class D.

Thanks for you thoughts.

In my application, the analogue component before the split has an output impedance of 75ohms at 1kHz. I contemplate splitting the analogue signal between: (a) an ADC converter (5.5kR or 5,500 ohms vs 14.5 kR or 14,500 ohms depending on the input), and (b) a Radial Twin ISO box (600 ohms in and out) which will feed an Schiit Mjolnir 3 preamp downstream.

If a split is a bad idea I could also simply use a switcher box, but I'd like to simplify the setup where there is no meaningful impact to SQ. What's the consensus within the hifi community on passive splits?

I have First Watt J2 and F4 amps, though the latter would need to be driven by my Don Sachs 6SN7 preamp. But those hot running Class A amps would be impractical for movie and TV sessions, so I’m looking for a high performance multichannel poweramp. But as my room is only ~ 2850 cu ft, the main speakers are at least 93db SPL/w/m and the center speaker nearly as sensitive, this MCH amp need not exceed much above 50 wpc, especially if a fourth channel can be bridged to drive the center speaker. Of course, wpc like this would be huge overkill.

https://emotiva.com/collections/x-series/products/xpa-dr3

Ideally, the amp will be biased to run in a Class A mode at low listening levels, which given >90db speaker sensitivities could often be the case.

And the amp must have balanced inputs as 8 channel DACs like the Okto DAC 8 Pro don’t perform well feeding unbalanced loads. Adjustable input level controls a plus.

Budget ~ $4K.

"Hey all,

Let's play an audio version of The Price is Right.

As in, what would you expect to pay for a passive, remote control, relay-ladder preamp...oh that also has a switchable, fully differential, fully discrete, 75-V rail, Class A gain stage...oh and that is made in the USA?

If you said $2790 or $27900, we wouldn't be surprised.

But that's not us. And that's why the all-new Saga 2 is $279. 

If you want to know more, here's the product page: https://www.schiit.com/products/saga_2 

Jason Stoddard"

by Marc Heijligers, 11-08-2024

A wish fulfilled

Since childhood, music and audio have always been among my greatest interests. I owned a CD player since 1984, just two years after its introduction, at prices that were just affordable for a high school student. Over time, I gradually upgraded my speakers and amplifiers. In 1992-1993, I acquired an Audio Innovations Classic 25 Tube amplifier, which underwent numerous modifications, paired with an Audio Note E (DIY) loudspeaker, this setup brought quite some musical enjoyment.

In 2003, I embarked on a new DIY speaker project with some friends, to address the shortcomings of the Audio Note E speaker (congested with complex music, coloration). A new amplifier was needed because the new speakers had an efficiency of 85dB/W, compared to the 92dB/W of the Audio Note, and the impedance curve had more dips and peaks. This was too challenging for a ~10W triode-mode tube amp.

I appreciated the rich sound of zero-feedback tube equipment and was drawn to Ayre's design philosophy, which promotes zero-feedback balanced circuitry. By 2005, I owned a CX-7 and AX-7, later upgraded to the Evolution (and eMP) versions. I was always amazed at how effortlessly the AX-7 drove the speakers, giving the impression it had much more power than its specified 60 Watts (@ 8 Ω). The treble attack was somewhat muted and the bass was less tight compared to other amps (a topic I discussed at length with Charles Hansen from Ayre).

In 2022, I had the opportunity to buy an EX-8 Full demo amp at a good price. Comparing it to the AX-7 revealed a larger soundstage, more accurate projection, fuller bass, and brighter treble. Overall, the EX-8 offered more authority, dynamics, and control. While the AX-7 had a slightly nasal and polite sound, it also had a certain "magic”. However, the benefits of the EX-8 outweighed these aspects, so I acquired it and later upgraded to the EX-8 2.0.

A few weeks ago, I saw a second-hand AX-5 Twenty for sale for a fair price. This amplifier, with its Variable Gain Transconductance, had always intrigued me and was high on my hypothetical wish list since it appeared in 2012. The seller was willing to demo the amplifier at my house, allowing me to audition it in my own environment. It took only a few seconds of listening to decide that I wanted to buy it. Let me explain why.

System Description

My current system consists of an Aurender N200 streamer, an Ayre QB-9 Twenty DAC, and the AX-5 Twenty (latest model with all the latests tweaks).

The speakers are DIY speakers, with a pretty flat frequency response (based on an-echoic measurements) and aligned phase response (hence the group delay of the units is the same, and all frequencies arrive at the same time to the listener, contributing to an holographic image). Impedance is amplifier friendly, never going below 5Ω.

First impressions

In May 2024, shortly after acquiring the AX-5, I had the opportunity to audition the AX-5 Twenty more extensively and with a wider variety of music, along with a friend.

In summary, this is the most organic, realistic, and lively amplifier I have ever heard. Its precision, articulation, texture and neutrality are amazing. This amplifier immerses you in the music, regardless of genre, recording quality, or volume. It consistently provides a strong “being there” experience that captivates and inspires.

When you are interested in an extensive decomposition of my experiences, read on. Every topic stands on its own, so arguments may be repeated.

• Tonal balance (timbre)
  The AX-5 Twenty has a timbre that feels authentic and natural. It maintains harmonic control and balance across bass, mid, and treble under all conditions. There is energy in every region, and no particular range stands out unnaturally as with many other amplifiers. There is no electronic haze, no exaggerated details, and no masking of details, resulting in a feeling of ultimate naturalness. This allows you to forget you are listening to electronic equipment and become fully absorbed and emotionally connected to the music. The amp does not exaggerate anomalies in certain frequency components of a recording; instead. This ensures the amp performs well even with less-than-ideal recordings.

• Bass (16-125 Hz)
  The amplifier sounds majestic, with a lot of grandeur, solid and powerful. The pace and rhythm are excellent, making the bass coherent with the rest of the frequency range and sufficiently dampened.
  Off Topic: There are many stories online about the higher output impedance of zero-feedback amplifiers resulting in less controlled bass. The effect of the 0,15Ω output impedance of the AX-5 is less than 10%, and will not be audible. See appendix 2 if you want more insights in this topic.

• Fundament (125-500 Hz) & Midrange (500-2000 Hz)
  The amplifier ensures that each instrument's and voice's fundamental and harmonic components are well-integrated, resulting in a coherent sound that is both full-bodied, and lifelike, avoiding an overly warm and mellow sound. It is a rich sound, which at the same time is not coloured at all.

• Presence (2000-4000 Hz)
  This is the region defining the articulation of voices and attacking energy of cymbals. Excessive emphasis in this range can result in harsh and fatiguing sound, while insufficient presence makes the music sound dull and muted. The AX-5 Twenty delivers ample energy in this specific segment without becoming overpowering. This significantly enhances the realism of voices and instruments, without inducing listener fatigue.

• Treble (4000-20000+ Hz)
  The treble is powerful yet refined, allowing instruments like for instance harpsichords to stand out subtly in a baroque orchestra, akin to real-life performances. It avoids sounding harsh, metallic, or overly magnified, which may initially impress but eventually becomes tiring. The treble is far from muted; recordings with significant sibilance on female voices sound fierce and clear without being rounded off.

• Dynamic range, Grip (scale)
  This amplifier operates without limits, effortlessly delivering without any compression or congestion. This capability remains consistent across all volume levels, showcasing the amp's absolute control. With energy consistently distributed across the whole frequency range, it maintains a balanced contrast between loud and quiet passages, allowing each to develop and decay naturally in the soundstage. An implicit indicator of its correct dynamic performance over the whole range, is its ability to facilitate conversation without requiring a reduction in volume, akin to the experience of live acoustic music.

• Attack & Decay (temporal development)
  The speed at which the amp can accelerate is very impressive. Such attack emerges from complete silence. Sound also decays into a black background without compromising brightness and details (it’s not disappearing and loosing details as with some mellow sounding amplifiers). What's particularly striking is the precision of the harmonic development. When for instance a string is plucked, the journey begins with the energetic release of the string, resonating from its fundamental area. This initial pluck sets the wooden front plate and the surrounding air into motion, resulting in a rich harmonic palette where the subtle nuances of the snare and wooden cabinet resonate alongside the primary tone. It can transition between notes with astonishing fluidity, capturing the dynamic nuances of the music with precision.

• Details, Texture, Resolution, “micro-dynamics” (fine details)
  What sets this amplifier apart is its exceptional ability to seamlessly integrate timbre, scale, dynamic development, and details throughout playback. Unlike many amplifiers that tend to exaggerate details, resulting in a constant haze that can become irritating over time, this amplifier maintains a perfect balance. This coherence is what truly brings the performance to life, making it feel realistic and deeply engaging, and drawing you into the music.

• Sound stage (sense of space, 3D)
  The AX-5 creates a deep and expansive holographic soundstage, characterised by air around the sound sources and multiple layers where the musical setting takes place, all while maintaining excellent imaging and separation. There are amplifiers that may project a deeper image, this is often achieved at the expense of an excess in the treble region. Upon careful listening, one may notice that the decay of sound in the depth of such amplifiers is limited to the upper frequency ranges, rather than the full frequency range. In contrast, the sense of space rendered by the AX-5 is impeccable, offering a balanced and natural representation of the music's spatial dimensions.

• Imaging & separation (pin-pointing)
  The AX-5 exhibits excellent pinpointing capabilities, ensuring that sources within the soundstage maintain a stable position and are accurately sized and delineated. Even in complex pieces, there is no tendency for the sound to smear or blur, allowing for precise localisation and separation of individual elements within the music.

• Long-term impressions
  After spending some months with this amplifier, my impressions remain unchanged. With every listening session, I continue to be amazed by the exceptional sound quality it delivers. Many friends, who now have also experienced the amp, share my sentiments—they've all been genuinely impressed.

Conclusion
Overall, each note is delivered with precision and clarity, allowing you to fully immerse yourself in the music, and to find yourself on the edge of your seat, exploring the different elements of the performance and uncovering the wide range of emotions and nuances that the artists are trying to convey. It's a reminder that there's so much more to music than just rhythm and melody; it's about emotion, expression, and the profound connection between the listener and the music.

Appendix 1: Comparison to the EX-8 2.0

The AX-5 Twenty outperforms in every aspect. It delivers a more organic sound, extracting richer textures without becoming “electronic”, while maintaining greater control, weight, and grandeur. The AX-5 excels in integrating timbre, dynamic development, and transparency, offering a beautifully cohesive experience. Vocals, violins, and pianos are articulated with a natural continuity, energetic drive, and harmonic richness that feels just right. While both amplifiers ramp up sound effectively, the AX-5’s attack is more precise, emerging from complete silence and decaying with grace. In contrast, the EX-8’s decay lacks the same depth, with a less black background. The AX-5 also creates a deeper and broader soundstage with more layers, enhancing imaging and separation without compromise. It feels like it has a proper cross-feed. With challenging music, I often find myself lowering the volume on the EX-8, but with the AX-5, I can comfortably increase it, even with demanding tracks. Both amplifiers provide a lush and warm midrange, but the AX-5 truly captivates with sources like voices due to its harmonic structure and timing of harmonics.

Does this make the EX-8 2.0 a disappointing amplifier? Not at all. It is a very good amplifier, the best I know for its price! I’ve compared it to many alternatives up to and above its price range, and it always came out as the best amplifier.

It reminds me of a previous experience that stands out in my mind; a visit to Peter van de Willenswaard with Guido Tent, around 1998. The reason for our visit was to listen to an Audio Note Ongaku amplifier that Peter had for service at his company, AudioMagic. At that time, the Ongaku was a €100,000 amplifier with a strong design philosophy regarding circuits and components. When we arrived, Peter’s push-pull pentode amplifier (a modified Philips HF309) was playing Stravinsky's "Sacre du Printemps”, on a pair of Audio Note E speakers. The sound was marvellous, captivating, and I was wondering “what could ever be improved”? When we played the same music through the Ongaku, a whole new world opened up. Compared to the previous setup, the sound was so “organic” and reached your soul so much deeper that it was almost a spiritual experience. Upfront, Guido warned me that after this session I wouldn't be able to listen to my own setup for weeks, and he was right.

This is exactly the experience I had with the AX-5 Twenty versus the EX-8 2.0. The latter is very good (best at its price range), but the AX-5 Twenty is a point of no return (but at more than twice the price).

Appendix 2: Terminology & Tech

Frequency range

The following table can serve as help for the terminology I use to describe certain frequency ranges

Output impedance

There are many stories online about the higher output impedance of zero-feedback amplifiers resulting in less controlled bass. The measured output impedance of the AX-5 Twenty is about 0.15Ω in the audible frequency range. Passive filtered loudspeakers typically have an inductor in series with the woofer; in my case, it's 4.7mH. At 35/50/100Hz, this inductor causes the woofer to see a series resistance of 0.75/1.5/3 Ω to the amplifier, in addition to the output impedance of the amp. This 0.15Ω output impedance has a 20/10/5% effect on the damping factor. I consider those values to be inaudible.

For the novice: see below the relationship between the speaker enclosure Q_TC (an indication of dampening), and the total series resistance that a woofer sees (amp + wiring + filter choke).

It show that a series resistance of 5Ω even doesn’t bring a speaker with Q_TC=0,5 (in my case) to a speaker with Q_TC=0,7 (also ignoring room reflections disrupting the impulse response even more)

So the 0,15Ω output resistance of the AX-5 is completely negligible.

Appendix 3: Music Auditioned

In the initial session, we have listened to the following tracks to review the amplifier (and enjoy the evening and music):

To suit 230V system, any Nema connector and cable isn't going to work, and Aussie connectors are few and far between of good quality, decided years ago to standardise on Euro connectors being of the right voltage and a wide choice of cables and connectors. Now to find a cable that's 10AWG and won't break the bank. Amazon.de have quite a few Chinese cables on offer for good prices, at least more reputable than e-bay, which want the money first, then ship, extending delivery to several months....

One cable manufacturer from China, Monosaudio at least has a website and unlike many cable manufacturers put their name on the cable, and by looks of the connectors, make OEM for other manufacturers. The offered power cable the 902R is a three core design, with each core screened and an overall screen with foil. I did have a look at other braided copper designs, however the coverage wasn't 100%, still allows a field to sneak in, which is not good.

For EUR107, the 902 1m, considering the size of wire is 'reasonable'. That's with MwSt, some 17%+ tax, which comes off export, that more or less pays for the freight form Germany.

The cable and the connector have a good quality about them, certainly no below spec. IR at 500V and sailed through that with no issues.  Removed the IEC connector to have a closer look, was worried about the collar unscrewing without a tool and exposing conductors, but this wasn't the case.  The colour coding was a little strange, Red for the Line (no issue) stranded white 16 AWGg for neutral (OK for USA), and black for ground, which is not OK, the PE should be green/yellow. The AAA battery is shown to compare the size of the connector and cable only. This cable is 2m.

 A better photo of the structure

Earth connection shown, black sleeving, maybe they wired it wrong? Earths cannot be multiconductor, but can be multi stranded.

The shields are connected at the male end of the cable, which is fine.

There are direction arrows on the cable, but since the connectors determine the source and load, it's kind of superfluus, however in a busy panel where mutliple cables converge, having the direction is very handy to identify cables.

The connector material looks like a varnished copper, could be heat or cold treated to give it that colour, certainly very even, not spotty at all.

In use with bi-amps, I made the box with the dual Furutech outlets. Internal wiring is 10AWG SPC.

The Monosaudio 902R have been in the system for a few weeks now, today received the 5m 902R and immediately the bass took off, the top end rounded off nicely, with no splash. Look, it's not  night and day, but definitely better than the Furutech Ag and pleasant to listen to. Depth much the same as before, I'd say the image stability has firmed, would put this down to the screening.

The factory is quite approachable, the 5m cable was a special at USD325, I think if they invest in an e-commerce software, sales would be a lot easier, but now rely on distributorships, mainly on the connector side. 

I was dubious about the Chinese quality and finish, however the Monosodio cables deliver great sound quality for the value they deliver, certainly would have to spend a great deal more for a small amount of SQ improvement.

Highly recommended!

This is my first post in the forum and I want to thank you all for allowing me to be here. 

I would like to ask your help in deciding what class D amplifier to buy. I need help deciding among the different options: Purifi, NC502, NC500X, Nilai, etc. 

I am new here, but I am not new to audio. Let me introduce myself. I became an audiophile more than 20 years ago. During my journey, I had many speakers such as the Danley SH50, Triangle floor standers, Triangle bookshelves, PSBs, NHTs, Tyler Acoustics, and some custom made horn speakers with Jabo horns. I also had many tube (SET, DHT, Push and pull) and solid state amplifiers, custom made and commercially available ones.

Around 2015, I had to do a radical downsize due to moving overseas, and I sold all my equipment.

Now, that I am based in north Virginia, I am finally rebuilding my system. My system is very humble at the moment. I have a MacBook feeding (with Audirvana) a Mini DSP Flex (via USB). The Mini DSP Flex sends high pass with some PEQ to Fosi V3, and also sends an open signal to a Rythmik L12 subwoofer. Fosi feeds main speakers, NHT C3 (85db, 6ohm).

My listening room is around 230 sq ft, and my listening position is 10 feet from speakers. I mostly listen around 70-75 db with peaks of 80-85db, this is measured with a sound level meter at my listening position. So, considering listening position distance from speakers, I do not need a lot of watts for my type of listening, but I would appreciate some headroom in watts for peaks.

On a subjective side, the NHT C3 are bright, but that can be tamed with some PEQ. Also on a subjective, personal, level, I listen to a lot of jazz, outlaw country, soul, indie rock, folk, progressive rock, among other more obscure musical genres.

Now, I am looking at the many Purifi stereo offerings from respected manufacturers (such as Boxem, Buckeye, VTV, Audiophonics, March Audio, etc) but I am wondering if with my current setup I would be able to even to listen the sound character differences between an Hypex Nilai, a Purifi or a NC502 based amplifier. I know the Purifi and the NIlai have a much better Sinad. But, I would also like to know how they sound from some of you who may own them or have listened to them.

Also, somehow, the ability to change op amps in some of the Purifi amplifiers (Audiophonics, VTV, Apollon, March Audio)  interest me because I can tune a bit the sound signature. 

I am only upgrading from the Fosi because I would like to experience this new, supposedly much better, generation of Class D amplifiers. 

Any help, ideas, comments, thoughts, numbers and/or calculations, are highly appreciated.

Thanks!

Alan Brain

I want to drive a ~ 90db SPL/w/m center channel speaker either of four ways:

1.)    A ~ 10 watt mono tube amp. Budget ~ $2.7K

From the DAC output feeding a LOW power tube amp. Driving the center speaker even with any of these lesser 300B SET mono blocks?

https://www.google.com/search?q=300b+mono+set+amplifier+between+$1,000+and+$3,500&udm=28&shoprs=CAESFhIUCQAAAABlzc1BEQAAAGC4E-pBGAEYBSoXMzAwYiBtb25vIHNldCBhbXBsaWZpZXIyMQgFEg8kMSwwMDAgLSAkMyw1MDAYAiIWEhQJAAAAAGXNzUERAAAAYLgT6kEYASoCGAFYprMgYAI&sa=X&ved=2ahUKEwj569e1l7mHAxVpEVkFHSYsCDkQ268JKAJ6BAgQEB8&biw=1066&bih=438&dpr=1.2

2.)   The other idea was a 45 tube amp, which I’ve heard can rival the sound of 300B SETs, but I can’t find any around.

Any suggested 45 mono amp under $2.5K? But do they run much hotter and/or have higher power draw than a cheap 300B mono block?

3.)   My stock First Watt F4 amp in balanced mono mode. https://www.firstwatt.com/product/f4/

https://www.firstwatt.com/wp-content/uploads/2023/08/prod_f4_man.pdf

As the F4 as a mono block does 100 watts, my room's only ~ 2800 cu ft and I'd be only 13 ft away how much input signal voltage could the F4 really need, even to sound it's best under these conditions? That's why I wanted to know if someone has ever put a balanced passive line stage between the F4 and a balanced output source-like a multichannel DAC, which will have a ~ 4.6V output.

https://static1.squarespace.com/static/5e15d4fba20f9d0f914ce7aa/t/5ecbdb96fd31365e4fd5daf5/1590418329103/convert-8-chop-shop.pdf

 Or this DAC card for the Merging Hapi DAC offering much higher output voltage?

https://www.bhphotovideo.com/c/product/1806156-REG/merging_technologies_700341_da8_output_card_up.html

Would there any loss in sound quality using a passive line stage like these, assuming their balanced stereo passive outputs could be bridged to feed the F4 in balanced mono mode?  https://khozmo.com/product-category/preamplifiers/

4.)   However, as many F4 users have said, as it’s quite the chameleon and will essentially sound much like whatever’s feeding it. Thus, the F4 in balanced mono mode fed from a fully balanced tube line stage? Budget ~ $2500. I would think this last option might be best as I would just need the best sounding tube line stage I can afford. But which for awesome sound stage size, spot on imaging, holographic mids and airy highs?

 Going kind of nuts with this. Please share ideas.

With transformers, the amplifiers see the impedance on the windings, in this case 53 Ohms. People have argued that transformers restrict dynamics, and this relatively high impedance is one of the reasons. So to overcome this issue, the pre-amp and power amps are connected directly to the wall (until a dedicated line can be installed, just one of those other jobs 'to do').  A dedicated line has the impedance of the AC mains network which should be less by a factor of 10 compared with the transformer, so dynamics are certainly restored, can vouch for that.

The main issue with the Equitech, used locally, it transfers the harmonics from the load to the primary where it creates an annoying buzz. On no load, it's quiet, but after 12 hours or so on load it creates that hum, with the rattle or to U2, rattle and hum, either is distracting!

By chance, was looking at the Denafrips site, and way down the back of the pages is a model BIC500EU or US. This device is also a balanced output transformer (115-0-115) for 230V mains input, or 60-0-60 V for 120V systems. Denafrips only offer one model at 500VA which is plenty for source components. I agreed with the dealer that the transformer would not be suitable for the amps, so they remained plugged into the wall for now.

Description

Nothing much inside apart from the transformer, a small PCB which as a line iron cored choked with about 15 turns of Phase and neutral windings. There's a 0.1uF cap, VDR and suppression device for protection against high surge voltages, but not lightning. Outlets for EU use are four Furutech gold plated outlets (receptacles). Iknow they are since I bought the same ones for another project. and I guess also a Furutech line input jack which is shiny metal silver colour, so not gold. No on off switch or meter, that's it. Weight is 6kg 13lbs. Checked the wiring, seems to be in regulation, the output centre tap is earthed.  Output voltage symmetry is not bad at all, only varying by a few hundred millivolts (if the mains kept still it would be easier to measure).

Price: USD779, you go no wrong here with the price.

Audio performance

With AC power, the topology of the system plays an important role and trying to fit a conditioner in is somewhat tricky. Begone are power conditioners with chokes and caps, like from Furman. Monster, they don't fit audio, but certainly use them for IT equipment, printers, computers and so on.  The BIC500 only supplies source components, these are listed in my profile, but essentially:

SACD player

DAC

Lumin U1 (using the AES3 to the DAC)

FM radio

DAB+, Internet radio

Turntable

AC Power cables: Furutech Nanoflex 18

Out of the box, vocals have air around them, and placement doesn't drift. This is from the Travelling Wilburys 'You're not alone any more', Big O vocals are centre high, background vocals occupy a little right of centre. The recording is not exceptional, that's the point, if vocals can be placed accurately on an average recording, then an exceptional recording works wonders. And it does, with Veronica Swift 'How lovely to be a Woman' just above the speaker line and such articulation. Lady Gaga never ending power on 'Diamond Heart' doesn't drift, stays rock solid, once again above the speaker line. 

I'd say there's more front to back image, than with the Equitech, where it was a little more confusing. Tonally, much the same as before which is a good sign, good image is working noise reduction. Certainly at idle, there's no noise/hiss from the speakers.

No rattle and hum either. Very impressed!

Rear view

Interior view, Denafrips claim the transformer is theirs from in house.

The PCB is mainly for the input treatment, simple LC filter network on the primary.

A few years ago I was given a non-working JVC TD-711 cassette deck. It sat in my closet for at least 5-years. I finally found a local repair tech and he completely refurbished this deck and when I picked it up he told me it was one of the best he's ever seen. According to him it was approaching Nakamichi quality.

So, I bought some Type II tape and made a recording directly from my Chord Hugo TT2 to the JVC. I chose a favorite album from Qobuz in 24/192 resolution that I knew had a lot of dynamics, plenty of acoustic instruments in a naturally echoic venue.

To my surprise... it sounded great. Of course this deck has every kind of noise reduction available and can make the most of the best tape types. But darn if that recording doesn't sound wonderful. My first thought, was "Why did we dump cassettes?" except that I know why.

I don't think I'm ready to go down that rabbit hole and start recording and collecting tapes, though I know many folks do that. But I wanted to at least comment out-loud that cassettes can sound really good.

Currently a Schiit Freya + preamp owner. Been overall pretty happy with it for the past few years until last week the tube stage went dead with no output (but the passive mode and solid state differential mode works fine)

Going to drop it off to my friend who is an amp tech to fix it.

Honestly i had been mostly using the tube stage of the Freya + for all my listening in my main system and wasn’t giving much love to the passive or solid state differential mode at 0db gain for the past few years…

In the meantime, I get to use the passive mode and the solid state mode and I got to say I am not sure if I miss the tube stage!!
 

Sure You don't get that holographic, expanded soundstage but especially the passive mode is sounding really nice, natural and organic!!!
 
I will get the Freya + tube stage fixed regardless but it really seems like I have now converted. I started looking at potentially getting a solid state preamp maybe a Benchmark LA4, Schiit Kara or maybe a Bryston BP173 and wonder what that will do to my system having a revealing preamp with gain compared to my current setup which is basically using the Freya + as a passive preamp for volume control!!!

The rest of my speaker setup is Ifi pro idsd dac or Holo Cyan 2 -> Freya + -> nuprime evolution sta power amp -> Monitor Audio PL200ii and 2 PSA 15” down firing sealed subs.

cheers and thanks for reading

Deric

Don't need a separate preamp, this one is a easiest part. Only amp's new, with warranty, do not need any second hand and discontinued items.. Thanks.
 

INPUTS:
3x Single Ended RCA (Cinch)

Largest Value 12Vpp (4.25Vrms)
Impedance 3.9 KOhm
2x Balanced  XLR

Largest Value 24Vpp (8.5Vrms)
Impedance 7.8 KOhm
OUTPUTS
1x Single Ended RCA (Cinch)

Largest Value 16Vpp (5.65Vrms)
Output Impedance 33 Ohm
2x Balanced Output XLR

Largest Value 32Vpp (11.3Vrms)
Output Impedance 66 Ohm

WEIGHT    9 kg
DIMENSIONS    430 × 260 × 55 mm

Measured performance:
Third party measurements here: https://www.l7audiolab.com/f/measurements-of-holoaudio-serene-preamplifierpre-retail/
Key specs:
>120dB SINAD (2nd and 3rd harmonics both below -145dB)
>140dB Dynamic range

Features:
- XLR-1 outputs can also be used as a 3 watt @ 32 ohm headphone amplifier (apparently holo will later be releasing a dedicated full-size headphone amplifier unit as well)
- Relay controlled volume adjustment in 1dB steps
- Chassis is the same as spring 2 / may and will stack perfectly if you have those (additionally the remote control works for both the serene and the spring 2 / may DACs)
- Fully discrete 8 channel amplification, with one module for buffering and one for amplification on each channel (two channels, balanced, with two modules each, so 8 modules total).
- All outputs driven simultaneously

Interesting - I am afraid to see the price.....

Long story short, I decided to buy this 1972 cassette because was fairly nice to see and at a decent price. 

It works and the sound is not bad for a 50 years old piece of equipment BUT, because there is always a but, it has quite a bit of wow and flutter.

Now, I changed the belt with a cheap one found on amazon, and cleaned the roller as much as I could, but I don't know if there is anything else that I could do to mitigate or solve this problem.          So, any advice is welkome! 

tube, class AB amps I have owned. This week I've just moved my Magnepan 1.7's to the much larger living room, after listening they aren't going back to

where they were before, even if I have to spend a weekend putting acoustic damping tiles up to kill the "cavern echo" of the room.

I want to beef up to a Hypex NCx500 design in a stereo chassis that will improve over the input section of the OA mono blocks and give me that added

current maggies demand.

Any suggestions in the $1~3K range?

its pretty good, but wondering if getting something dedicated like a crane song Interstellar might be a better option

the tube diode controls seems very interesting to play around with

anyone have experience with high end ADC for vinyl ripping

thanks !

The amp is a Proceed Madrigal HPA2, essentially a Mark Levinson, 250 amps into 8 ohm, approx 500 into my 4 ohm Aerial Acoustics 7B towers.

From time to time the amp will 'stop' briefly in response to turning on a light or other appliance in the room on the same circuit. It starts playing again almost immediately. I don't know if this is protection mode or simply the power dropping below a certain level. But, it is certainly aggravating.

I'll preface this question by saying I know very little about electricity. What I'm wondering is, would running a dedicated line back to the breaker box (which is modern and has a few open breakers available) help with this problem? If so, what amp breaker?

I will also say that this is not intended as a sound quality upgrade of some sort. I just want the amp to stop cutting out. Thanks,

George