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Jeff Checking In: Acoustic Revive, Audio Note (UK), Duelund, iPhone Adventure, Spatial Audio Lab, and music!

04-22-2024 | By Jeff Day |

Greetings friends, I hope you are doing great! 

Life just seems to keep getting busier, but in good ways. 

As I transition into the Winter months my activities tend to shift from outside to inside. I go full INFJ with my writing, reading books, music, audio, weight lifting for exercise, and just generally enjoying a contemplative lifestyle. 

But the Winter months have faded, Spring is now in full bloom, the temperatures are starting to warm up, it's nice to get out and about on two wheels for bicycle & motorbike rides, and of course my audio systems are rockin'! 

The latter is of course why you've stopped by to visit, and I've got lots of cool music & audio adventures to tell you about. 

RHR-21 room tuning devices

Acoustic Revive RHR-21 room tuning devices end views.

I've been methodically working through the exotic and beautifully crafted Acoustic Revive accessories that I mentioned in my January Today's Fresh Catch article in preparation for their upcoming feature review: Chapter 15 of the Acoustic Revive Chronicles

Acoustic Revive RTS-30 turntable mat on CTC 301

Acoustic Revive RTS-30 turntable mat on my CTC Garrard 301.

Some are completely new to me, like the RHR-21 Helmholtz resonators (more HERE and HERE), the RTS-30 turntable mat (more HERE), and the RHS-1 headshell (more HERE), for example.

RHS-1 headshell

The RHS-1 headshell is the result of a collaboration between Ken-san and Shinichi Masuda (Fibonasound), who is a artisan master of headshell design.

Others are improved versions of Acoustic Revive accessories that I've already written about in previous Acoustic Revive Chronicles articles (see the full list of articles in the Archives), like the CS-3K outlet stabilizer, the RCI-3HK cable lifts, and the RGC-24K ground conditioner. 

My primary music system based on my Tannoy Westminster Royal SE loudspeakers, with lots of Audio Note (UK) kit making life beautiful.

I'm working on the feature review for Positive Feedback of the Audio Note (UK) Tomei 211 SET integrated amplifier and M3 RIAA phono stage combination. 

The Tomei and M3 RIAA phono stage combination are absolutely stunning in what they are capable of.

Led Zeppelin studio album from 1969.

My buddy Chad came down to visit from Chelan, and brought along a copy of Led Zeppelin's first studio album from 1969 (the 1977 reissue version), that he found languishing in the basement, unplayed since 1977. 

I put it through a couple of cycles on my VPI record cleaning machine to get it all sparkly clean, and we put it on the turntable for a listen. 

We were absolutely blown away with what the combination of the Audio Note (UK) Tomei 211 integrated amp and M3 RIAA phono stage did for this album. It was one of those vinyl listening experiences where words just can't do justice to the exalted experience of hearing such a classic album played with such a stunning combination of sound quality & musicality.

Audio Note (UK) Tomei 211 SET integrated amplifier with the M3 RIAA phono stage.

If you are one of the lucky few who've got the dough to add the Tomei 211 integrated amp and M3 RIAA phono stage combination to your audio system, it's a no brainer. I've never heard - for my tastes - anything else that can run with it. 

Here's a LINK to my latest Listening article about the Tomei 211 integrated amp and M3 RIAA phono stage combination to keep you going until the full feature review appears at Positive Feedback.

Duelund DCA10GA speaker cables. 

If you haven't had a chance yet to check out my latest Listening article on the new Duelund DCA10GA speaker cables, you can catch up HERE.  

I did a recap of all my Duelund tinned-copper cable adventures for you, as well as offered some ideas for 'art of tone' projects that will give you hours of fun experimenting with them in your audio system, along with my impressions of the latest DCA10GA speaker cables. 

It's not often you can get such stellar cable performance for such reasonable prices, so kudos to Frederik Carøe of Duelund Coherent Audio for making that possible. 

Yazaki-san's "Improved U4" vacuum tube Bluetooth/USB DAC.

I'm sure you've heard all about Yazaki-san's iPhone Adventure by now (intro HERE), where he has collaborated with his friend Honda-san and modified an affordable Douk Audio U4 vacuum tube Bluetooth/USB DAC to stream music over his iPhone. 

You know how young people - and us old geezers - have been causing a resurgence in vinyl listening and record sales?

Well we have, but there's also something else important going on in audio where the majority of young people are now listening to music streamed from their iPhone to their hi-fi, or over headphones. 

Only Yazaki-san and his friends have had the opportunity to hear this mini-marvel Improved Douk Audio U4 vacuum tube Bluetooth/USB DACs up until now, and they have been enthusiastically praising its performance in the group emails I have seen.

A big thank you to Yazaki-san for sending me one of his Improved U4 vacuum tube DACs so I could join in on the fun too!  

What happens when a couple of World Class professional audio engineers like Yazaki-san and Honda-san decide to modify a simple U4 DAC with a few top-notch components and circuit improvements?

Well now ... you can add me into the group of Yazaki-san's friends that have been astonished at the sound quality and musicality of this DIY U4 DAC project.

I didn't really know it was possible to get this impressive of a level of quality when streaming audio from an iPhone.

I mean how does the Improved U4 work such magic with what are typically low-resolution audio streams?

My vintage Altec A5 Voice of the Theatre loudspeakers based audio-visual system with the Yazaki-san's Improved U4 DAC.

I've been listening to the Improved U4 in my A-V system based on Altec A5 Voice of the Theatre loudspeakers, and I'm extremely impressed.

As an aside, my A5s use Hiraga-san inspired crossovers - wired with vintage Western Electric WE16GA tinned-copper wire - with a few tweaks by Yazaki-san, so that they are optimized for boundary positioning in my A-V room (spare bedroom). 

The speaker cables are the Western Electric inspired Duelund DCA16GA, along with the Yazaki-san recommended Belden 8402 tinned-copper microphone cable interconnects.

The amplifier is the Yazaki-san designed and voiced SPEC RSA-M3 EX Real Sound Amplifier, which does a credible job of sounding like a fine single-ended-triode amplifier, but uses a cool running Class D design that is perfect for the hot Summer weather that will be coming up soon.


While you can stream from any source on your iPhone, I've been primarily listening to Seattle's superb Jazz24 radio station stream HERE, and I'm blown away with how good the Improved U4 makes Jazz24 sound. 

I've never heard this level of inner detail, musicality, sound quality, and such a smooth & organic presentation of music from my A-V system, as I have from Yazaki-san's Improved U4. 

The Improved U4 completely trounces my Mhdt Labs Havana vacuum tube USB DAC, which is an excellent performer in its own right.

Note that the same vacuum tubes that are used in the Havana can be used in the Improved U4. 

Yazaki-san's Improved U4 in my A5 system.

By the time you buy a Douk Audio U4 and the select DIY upgrade parts to build one according to Yazaki-san's instructions, you're only talking about $500 USD or so, for what is truly impressive performance. 

While the Improved U4 is primarily intended as a DIY project for you to do on your own, due to the tsunami of interest in this project by readers, Yazaki-san has said he will build a few for people who don't have the requisite technical skills to do the project on their own.

Yazaki-san will build a few Improved U4s on a first come, first serve, basis as he has time to work it into his schedule. Contact Yazaki-san about details and scheduling at [email protected]

I'm working on my next installment of Listening for the Improved U4 now, but if you haven't had a chance to read my last Listening article about my iPhone Adventure with the Improved U4, you can catch up HERE

I would absolutely love to hear what Yazaki-san & Honda-san could do with an inexpensive modded CD player so I could play my 78 transfers through it. That's not a project that's in the works, I'm just Day Dreaming ... 

Spatial Audio Labs

Doc David just asked me if I would like to write about the Spatial Audio Lab Raven Preamplifier and a pair of their Blackbird 300B monaural amplifiers for you here at Jeff's Place and Positive Feedback. 

After a quick perusal of their webpage, and being intrigued by what I saw & read, I replied with an enthusiastic "Yes!".

It will be a while out before the build of the Raven pre and Blackbird 300B monos will be ready, but when I receive them I'll go through my usual Today's Fresh Catch, First Listen, Listening, etc., articles process, before I write their final feature review for Positive Feedback, sometime towards the end of 2024 (probably). 

I'll be looking forward to it!

My 100 year old gramophone.

I had planned to tell you about some great new 78 records transfers I bought, and a couple of other recommendable albums, but I've run out of time for writing today, so that will be for next time!

As always, thanks for stopping by, and may the tone be with you! 

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