Muzak listening system

Hi - I have been a long-time audiophool, mostly hanging out in the past at AA and the Altec User's Board (which is now rife with the sound of crickets), and a now defunct NZ board, AudioEnz.

Recently, I have been distracted on rebuilding my '74 Norton Commando that I have had for almost 35 years. So, a lot of time spent on a Commando forum... A lot.


I built my first horn speakers in my high school wood shop class, Speakerlab 6 kit, which used a proprietary 12" woofer and EV mid and tweeter horns in a sealed box. I loved them and played them loud for years.

Then I got distracted and they ended up in the rec room.

And then I started on tubes. Down the rabbit hole I went.

It started with a Cary SLP-98P and SLAM-100 monoblocs to drive my inefficient Mirage OM-7 speakers. I moved to New Zealand with them from Seattle, and tube rolling ensued.

And then horns called again, and I started lurking about and GPA came out with their 604-8H-III, with the exponential horn. I bought these right out of the gate, and they are SN 003 and 004! And I know who got the first two, I was just a tad slow.

They lived for a few years in 22mm Gaboon ply JE Labs Open Baffles that I whipped together in an afternoon.


But then...

At ~10 cubic feet/ 286 litres with a 6” bottom port, these are the biggest physical change to my system ever. However, they aren’t quite as heavy as I had imagined they would be, but they are not lightweight either! I'd had this wood sitting in my shed for 3 years, and I had a wood shop teacher at a local school help me do these.



These cabs are a variation based on GMs original design done for Jay Fischer, which then formed the basis of the 6Moons Altec Dream article. One inch Baltic Birch with American Walnut veneer, double thick tops/bottoms, no internal bracing or stuffing. Originally, I had stuffed it pretty well with a cut down medium weight duvet hanging diagonally and across the top, and then progressively removed the stuffing and found they sound best with none.

In general, the sound quality is very very nice. It certainly is different (better) having the drivers at ear level vs shin level as they were in the JE Labs OBs. The upper mids are definitely better - more detailed/articulated. Snare brushes are coming through with a lot more clarity and expression now. Much better control and imaging than the having them in the OBs (where they had been for a few years). Excellent imaging.

They also sound much better with ply under the cabs. The thick carpet and underlay really sucked the bass out of the bottom firing port.

Even the wife appreciates the sound. Just not the size.

But, obviously, the big monoblocs were too big. Quite a while ago when I was trying to get rid of them, I came across an inexpensive Consonance J400 parallel single ended 300B amp for relatively little money. But, I found that it was just too soft and flaccid, that it hummed a bit too much, and it had too much gain. So, I wished it well and it found its way to someone else.

Somewhere around that same time I borrowed a KR Antares amp. I had high expectations for the demo given what I had read, but I found it quite the antithesis of the feedback from others that I had seen: it was dull, lifeless, slow and pondering in my system. And, in talking with others who had also heard it, they seemed to concur. So, back it went. Hmmm... is this the 300B?

Then came along the Sun SV-2A3 SE amp that I still love (and others), and I thought briefly of doing the simple mods to make it a 300B amp. But, I liked it too much as it was. Mudorf SIO caps, Vishay and Mills R, WBT Nextgen silver RCA, Eichmann cable pods, EML mesh plates, etc., ad nauseum.


Also, to come and go about this time was a Don Allen GZ34/6BQ7/KT88 SE amp. The Don Allen is a nice amp, with plenty of bass punch. Not quite the delicacy or the richer mids of the 2A3, but it was good and very responsive to driver tube changes, and the 50s RCA black plates do wonders for it. But, at the end of the day, Meh! Gone.


I will digress. I got a bit greedy when the top floor of the house I still had in the USA was burned up by a lodger, and I had to rebuild it with the insurance and then decided to sell. The Cary wasnt keeping up with this, and other things (down the thread..). It was a great first tube pre, but its replacement may be a pre-for-life. A green monster: Shindo’s Vosne-Romanee. I bought it used, and got a screaming deal on it. The VR is very, very nice. Almost too-nice. A harbinger of sorts. But, now I feel no need for another pre-amp.

Instead of going on about how nice it is, I am going to stop and just listen to Jerry Mulligan and Chet Baker for a moment.

Ahh, that’s nice.


So, back to amps....

And then my friend Ken passed, and I helped his widow liquidate his extensive audio estate, and for a gratuity from them I took his beloved red home brew amp into my home. It was a nice E180F/300B SET amp, with a very alluring sound. Not the most sexy looking amp, as it has been around the block a couple times. But it had a very clean tone and rich presentation.


Hmmm... now is this a 300B? But, after living with it for a while I found I wanted more. More drive, more bass control. Meaner. Less nice. Less single-ended.

Paradoxically, I ended up buying and keeping his very nice Copperies - copper clad DC 417A/45 monos. Love them. Again, EML mesh plates (not pictured) are the bomb. Great for when the family is asleep and listing to some nice old jazzy stuff.


So, then I borrowed a friends Shindo EL84 Montille. Now, I am not a fan of EL84 PP amps, having extensively used both a modded Leak Stereo 20 and a DC ECC85/EL84 Baby Huey amp previously. Boy, was I wrong. Wow. Fantastic amp. I probably could live with that amp.

But, I am a greedy SOB and I remembered a review of the Mactone PP 300B. So, Mark the Dealer was kind enough to bring it down one evening. Simply put, it is a nice amp – but it just didn’t float my boat. It didn’t wow me like the Montille did. In fact, that night I realized that the idea of the 300B and I would have to part ways for a while. Try as I might, we aren’t a good match.

But, between the Mactone and the Montille, I did find that more power was not a bad thing for me. I have the Copperies and the Sun amp – which has so much gain and drive it can play like an 8w 300B amp – but with a cleanliness of tone that is the 2A3. I love it’s sound. But, I also like to hear it across the house. So, 20w might not be a bad thing… but having not really gelled with the Mac – I couldn’t see taking a big punt on its 2A3 PP little brother.

So, I went back to someone who I know had been trying to sell these Shindo GM-70s for a while and they were still there, and a deal was struck. A pretty good deal, I think, including shipping.


These amps aren’t perfect. They had been played a fair bit more than I was led to believe – I could tell by looking at the power tubes and these old girl’s thinning grey getters say that they are d'un certain âge, having been around the block a few times, and were tired.

So, the Lafon was sounding sort of closed in and congested, and I was wondering if new power tubes would really change it that much? The sound was in the room, but it was in a ball. Nothing like the Montille. Or my Sun. But then I tried a suggestion from a fellow Shindophoole and swapped the speaker leads from the 8 ohm taps (my 604s are 8 ohm) to the 16 ohm taps. Now, the room is in the sound. Wow.

No, WOW!!

I didnt really see a loss of power. In fact, maybe the inverse? I was shut down my the wife at midnight shortly after the 16 ohm swap, so I need to listen a bit more closely. So, maybe the taps were reversed somehow? Dunno. Must investigate a bit.

In some quick research, I ran across some comments from Paul Joppa (Bottlehead):

"A really good transformer designer will try to optimize the balance between extension and smoothness, and would either use a single secondary, or adopt one of the "clever winding methods" to eliminate the variation from multiple taps. But even when this is the case, the designer's choice of "optimum" sonics will not be a match for every amp/speaker/souirce/listener/etc

Fostex speakers usually have very large magnets for their light cones. The large magnet increases efficiency, but often results in somewhat over-damped bass. In many cases, a reduced damping factor in the amp will bring the system (speaker plus amplifier) into better balance. Using the 16 ohm tap with 8 ohm speakers will halve the damping factor."


"exactly... what Mr. Joppa said.. I have noted this as well... at the time it was with an SE GM70 copper plate, but I heard the same things as brother Dave... to test the higher output impedance theory I swapped back taps and added a two ohm resistor... same type of change to the sound...

I guess it is just raising Qes and therefore Qts.. and with respect to the cabinet, just raises to total system Q... this juices the midbass a bit... adds some yummy if you need it... "

So, if what I hear from other Shindo owners is true, and they have good experience with running off the 16 ohm tap, and Shindo is known for his affinity with vintage Altec and JBL gear (which is 16 ohm as you go back in time) then it may make sense that, as a designer, he is optimizing for that operating point?

Oh, and the 604 is a fairly low Qts and Qes driver, so this may have a part...

And more oh - some NOS copper plate GM-70 and 6AWA cleared the rest right up. Happily running for years now.


The but will likely come in a few months...
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Other stuff happened along the way.

I was never very happy with the stock GPA N604-8A xo. GPA notes say, “Full-section with 1,500 Hz crossover frequency, 12 dB per octave slope for the low frequencies, and 12 dB per octave for the high frequencies.” My ears say, “Very shouty”.

For a long time I used a custom xo made by the late Rick Craig at Selah Audio. Rick's is much, much nicer - very smooth and not nearly as much "shout". I was very happy with it, even with basic "stock" parts. I have talked to several other 604-III buyers who have also bought Rick's xo, and were very happy with it.


From Rick:
"I didn't really pay any attention to the stock crossover or specifications when creating the new design. The drivers were tested for frequency response and impedance and then everything was imported into our software optimization program.

This combination presents a difficult challenge in that there's very little overlap of the driver response curves due to the fairly small horn and large diameter woofer. The woofer has a significant breakup in the 1.8K-3K area The tweeter also has resonance issues in the 1-2K area. The shaping of the filters around the crossover point is critical and choosing the place to cross isn't easy.

I started first with a lower parts count crossover and experimented with different topologies. The objectives were to maintain good phase response in the crossover region, minimize the resonance and frequency response issues, maximize horizontal dispersion coverage, and provide plenty of headroom to keep the horn distortion low.

The crossover's acoustic slope target around the crossover point was 24db/octave. There are different ways to achieve this and a third order electrical filter was implemented for the tweeter. The woofer filter is a first order combined with a parallel resonance trap. Both are far from textbook values and designed to work in tandem with the driver responses to achieve the desired acoustical transfer function.

I also added a conjugate filter which creates a smooth system impedance. This is important for tube amps, in particular SET designs which typically have high output impedances. The less reactive load will provide better results and insures compatibility with virtually any tube amp."

Recently, after hearing so much good word for so long, I purchased a set of Werner Jagusch’s xo with autoformers and motor-run caps. Wow. Transformative. Clear, smooth, detailed. So nice. Worth every penny. I sold the GPAs and Rick’s are on the shelf.


I recently undertook a bit of an experiment and built a pair of red neck bucket subs (I had meant to do this, what, 10 years ago?) which I am running bridged mono with a Crown 1502 amp. I am generally very happy with the experiment, but the Crown is noisy, and the buckets are ugly (despite the fact I used shiny gloss black buckets the wife says they have to go). But I am loving them – they have that missing bit I didn’t know I was missing, and they integrate seamlessly with the Altecs in the big cabs. So much so, I am scared to buy anything that has higher WAF. Likely will test some big SVS subs soon.
And some vinyl stuff happened along the way...because I love it.

I got rid of the Rega P3 I got when I moved to NZ in 2004. I think I upgraded?


I wont go into how I built it to this state too much here, but I do love it and I wouldnt trade it for something, even if it was marginally better. Well, maybe.... You can read more about it if you want on The Analog Dept. and see pics of the build on Flickr.

I got an Analogue Instruments Apparition arm from one of James’ first lots (he was an arm builder for a while here in NZ).

He was gracious enough to come up and help set it up, and we had a good listen (back when the 604s were still in the OBs). In the shoot-out with my Thomas Schick arm, the Apparition killed poor Herr Schick’s tired arm. Well, it was barely broken in, so it was not so tired, really. But, it was absolutely no contest – James’ arm rocks, swings, and finessed the Schick to a new home on a 401 in the States. Aufweiterzien, sucka!


This is an old video from James' place

Also new on the phono front was the Miyajima Shilabe, which I love. A nice upgrade from the Benz SL I previously had in every respect. The tone of the Shilabe is just so nice!

But, the Jensen SUT that I have been using forever was a terrible match for the Shilabe. Enter a Bob’s Devices Cinemag 1131 Blue.


These are special edition trannys, hand wound by the top man at Cinemag, David Geren. Bob also has a Shilabe he uses in his home system, and said the 1131 Blue was one to get. He uses it, as does the Miyajima rep for the US uses it (says it is better than Miyajima’s ETR-800 SUT). So, I got the 1:20/40 version. I have no regrets on this one, it is the best SUT I have heard.
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Next Round Is On Me
Site Supporter
Welcome to the haven. Great taste in gear and quite the journey! Shindo is one company I’d like to try out due to the synergy and creators use of Altec drivers.
Thanks, I have had that Norton since the days when my Speakerlabs were my only audio, powered by a nice HK 670 receiver and a crappy JVC tt. 4AD days...

Digital stuff happens too...

Back in the days when I had my old Mirage setup, I was using a Musical Fidelity A3 CD and A3.24 DAC (you can see them peeking from under the 401). It was ok. ish. No great shakes. But, I was listening to a lot of vinyl, so whatever. VINYL RULES!! right??

I had long since said to myself, "no new CD player or server till that CD player dies".

Several years ago, I went to play a CD and hit the play button and POOF. Smoke actually started pouring from the CD player! When I performed surgery on it to retrieve the CD, I could see the toroidal had melted its insulation. Kaput.

One of the AudioNZ forum members was Mark Cole from Antipodes Audio. He started out making some very swish cabling, that was out of my price bracket back in the day, even though he gave us NZ'ers a discount on the overseas retail price. And then he started building himself a music server. And another. Then for others. You get the drift.

So, I went looking for a server and found a sweet deal on a trade in DX unit, which the factory graciou$ly has upgraded for me a couple of times to the guts of the new Oladra unit. So, it looks like a family sedan, but it has a V12 under the hood. Price effective.


"The Oladra employs an innovative new Server engine, plus enhanced Player and Reclocker engines. A new power scheme involves a triple cascade power supply macro-topology integrating four unique micro-topologies."

It is a great unit, and with the old DX chassis, it has a built in CD ripper - stick one in the slot and it automatically rips the CD to Flac-0 and downloads the album art from the internet (ethernet connected) et voila. No user intervention. Runs Roon, Tidal, QoBuz, Squeeze, SC, HQplayer, MPD, and more.

The DAC is a mouthful - Holo Audio – Spring 3 DAC L3 Kitsune Tuned Edition. Some better marketing required. But, the approach is interesting, to quote the presser:

"The HoloAudio Spring is a member of an interesting but nearly extinct subfamily of D/A converters called R-2R or ladder DACs. Ladder DACs date back to the dawn of digital, and use cascaded voltage dividers consisting of resistors (valued R and 2R) to passively convert pulsing bitstreams to continuous analog voltages.

The original Philips/Magnavox CD players of the 1980s were multi-bit R-2R designs whose 14-bit Philips TDA1540 chips used oversampling and noise shaping to get nominal 16-bit performance. That chip was replaced in 1986 by the TDA1541, a genuine 16-bit R-2R DAC. Around 1990, single-bit sigma-delta chips superseded these benignly musical multi-bit chips. Of course, just as when transistors superseded tubes, not every audiophile thought the new part was an improvement. Some fraternities of audio cognoscenti (most of whom were still using tubes) clung to the TDA1541A, which remained in production until 1995.

The last hope of those who clung to R-2R, Burr-Brown's venerated PCM1704 24-bit/96kHz chip, was discontinued in 2015. Since then has emerged processors using a new breed of meticulously executed chipless, discrete-resistor ladder DACs, obvious examples of which are the American-made MSB Technology Select DAC ($84,500–$119,985) and the French-made Totaldac d1-six (?13,500). Unfortunately, those DACs' massive linear power supplies and arrays of discrete, high-stability, low-tolerance resistors are expensive to make."

The Spring cost nowhere, anywhere, near that. No way.

But this is just the back story. These two units together have almost made me stop listening to vinyl. My old CDs sound sublime. Streaming Hi Res from Tidal or QoBuz sounds great. No snap, crackle, pop of LPs, but oh well. Not better than vinyl, but different. But pretty much as good. And easy. I can stream from my server using my phone as a remote control. I can stream to my home office desk where I am sitting now with my crappy NuForce Icon2 and Tannoys listening to a brand new disco album I have never heard of before, That! Feels Good!

And I can still listen to CDs on the old tank if I want to. Thanks to my late father in law, George.


And it is a tank.


It uses then-top-of-the-range Pulseflow DACs. Built for Pioneer by an un-named specialist, these true 1-bit DACs include four second-order noise-shapers and a total of eight differential PDM output stages, all running at 384 times oversampling.

Not great.

I run the Holo DAC in NOS mode (No Over Sampling) for good reason.

But, I play the Christmas mix CD every year when we open presents. George loved Bing, Doris, and the Rat Pack.
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WElcome to the forum!!!!. I will say one thing, YOU keep the audio stuff, I want the Norton.
I have never seen one with siamesed pipes like that.
I did have a 1958 Triumph Tiger 100 that had them from origional, but like a fool I sold it.
Didnt handle like the Norton does ( DONT forget the suspension bush shims ) but was a beautiful bike.

Cheers from Australia.

WElcome to the forum!!!!. I will say one thing, YOU keep the audio stuff, I want the Norton.
I have never seen one with siamesed pipes like that.
I did have a 1958 Triumph Tiger 100 that had them from origional, but like a fool I sold it.
Didnt handle like the Norton does ( DONT forget the suspension bush shims ) but was a beautiful bike.

Cheers from Australia.

Hey bro!

The pipes are made by a mate of mine down in the Hawkes Bay. But, he took over making them from a well known race shop in the UK after that guy retired. Steve Maney. +6 BHP with the pipe. And it growls.

I don't need no stinkin shims now. I have vernier adjustable isolastics. Also compression and rebound dampening in the forks too. Handles damned fine. And light. In ways, better than my modern Ducati.