ADC 303AX Speakers

Acoustic Dynamics Corporation, ADC 303AX speakers came my way yesterday. This sealed 2-way speaker is right out of the early 70's and competed with the usual suspect including AR, KLH, Dynaco, Jensen and others.

 These speakers were built around CTS Alnico woofers and a CTS tweeter that also has a doped surround, before the infamous yellow phenolic ring tweeter.

The sound is very deep in the bass region smooth across the mid range and the highs were surprisingly crisp and clean with great dispersion.

Real walnut veneer cabinets are in good shape with all corners square, the usual Wabi Sabi* scratches are evident event after a light sanding and a coat on MinWax and I am fine with that. In fact I prefer Wabi Sabi to modern standards.

 These sound best through the Single Ended tube amp, in fact they sound fantastic, I am well surprised.

An old ad was found on the Audio Karma site from a discount store called Dixie's and you can see where they fell in the pack.

Generous gobs of the doping material have sufficiently cover the crossover that make the 6uf cap un accessible so I will just leave it as it is.

*Wabi Sabi: Japanese for the art of imperfection.



Broadly, wabi-sabi is everything that today’s sleek, mass-produced, technology-saturated culture isn’t. It’s flea markets, not shopping malls; aged wood, not swank floor coverings; one single morning glory, not a dozen red roses. Wabi-sabi understands the tender, raw beauty of a gray December landscape and the aching elegance of an abandoned building or shed. It celebrates cracks and crevices and rot and all the other marks that time and weather and use leave behind. To discover wabi-sabi is to see the singular beauty in something that may first look decrepit and ugly.

Wabi-sabi reminds us that we are all transient beings on this planet—that our bodies, as well as the material world around us, are in the process of returning to dust. Nature’s cycles of growth, decay, and erosion are embodied in frayed edges, rust, liver spots. Through wabi-sabi, we learn to embrace both the glory and the melancholy found in these marks of passing time.

Electrohome Kalmar 120 push/pull tube amp with Phase Linear Model 3300 pre amplifier

I have been lucky enough to be listening to a Electrohome Kalmar 120 push/pull slave tube amp connected to a wonderfully clean Phase Linear Model 3300 pre amplifier.

The Electrohome Kalmar 120 is probably rated around 25 watts per channel and does an incredible job at powering any of my speakers to their best.

The sound is deep and powerful in the bass region, coupled with an incredibly open and transparent mid range topped with silky smooth treble that is crisp and clean.

There is a huge difference between the sound of tubes versus the sound of solid state gear that when comparing A/B between the both I find myself returning to the tubes.

So far this amp/pre amp combo sounds best with the Tannoy Oxford Golds, then the NAD Model 30's, it makes my Mission 770 Freedom IV's really come alive and with a bit of equalization, powers the University RRL-12 to new heights. Not saying that this combo does not do any other speakers in my collection justice, I just find myself coming back to the speakers noted above.


How does a Single Ended tube amp compare to a Push/Pull?

To my ears the single ended tube amp is not a clear in the bass region but far more open and forward in the upper mid range/treble region. The push/pull has much more punch and control in the bass along with stronger lower mid range. The upper mid range is a little more laid back and the treble region is not quite as hot/sizzling.

Both are amps are a true window into music with proper and I mean in the room with the musicians sound, the imaging is transparent, clean and true.

Once bitten by the tub amp sound one has a hard time plugging the solid state back into the wall.

University RRL-12 Speakers

A friend of the blog arrived this week with a pair of immaculately refurbished pair of University RRL-12 speakers. The RRL-12 speakers feature 12" woofer with Alnico magnets along with a 5 inch midrange with Alnico magnets and a wonderful dome tweeter.

This pair of University RRL-12 were lovingly and painstakingly redone with mint cabinets and crossover that have high quality Erse and Solen capacitors along with audiophile grade resistors.

With a little tweaking with the brilliance control on the back along with a little added bass and treble powered through a push/pull Electrohome Kalmar 120 tube amp and these speakers sound absolutely fantastic.

Once the equalization was figured out the sound was very open and transparent with incredible detail and depth, by depth I mean the 3 dimensional image of where the instruments and vocals have their place in the room. It is as if you are in the same room as the musicians, the clarity can only be realized with a tube amp.

This surviving pair of University speakers are a real gem to grace this audiophile blogger.

EPI 100V crossover upgrade

The EPI 100V is a wonderful speaker that has graced this blog an multiple occasions and this latest pair is another example of how a simple internal wiring and capacitor upgrade brings out the best in this speaker.

Once again the latest pair that I picked up got the royal treatment. One thing I did notice is that the woofer had been refoamed already with the distinct signature of Vancouver Audio Speaker Clinic all over it.

The old really thin speaker wire was replaced with proper thick copper wiring along with a Solen Metalized Polyester cap. I also like to add proper binding post to accept banana plugs.

This simple upgrade is a night and day difference and always worth doing.

Acoustic Research AR 18B Speakers

My second pair of Acoustic Research speakers to grace this blog the AR 18B speakers. My last pair was a pair of AR-15's that needed extensive restoration.

The AR 18B is a early 80's refinement of the AR18 and AR 18S, this pair uses well matched woofer tweeter combo where a single 5uf cap is used for the roll off for the tweeter at 4000hz. The woofer is designed to roll off naturally.

This pair needed a re foam given that they are 30 years old and I figured a new Solen 5uf cap was pretty easy to replace and upgrade.

Straight forward these speakers sound much better through the Noresco 2570 than they do with the tube amp. There is ample bass from the 8" woofer and very smooth across the lower mid range. The upper mid range is a little less forward, perhaps laid back. The high notes are typical of a cone style tweeter that tend to roll off reducing the crispness that a dome tweeter produces. Cymbals sound a little blurred when A/B comparisons with the EPI A70 speakers. The efficiency of the AR 18B's is reported to be 86db at 1 watt which could benefit from a mid range power amp of 25-50 watts per channel.

Over all these are a nice compact bookshelf speaker that seems to have a small cult following on the interweb machine. Some even some go on to say that these have been used in studio's in lieu of the Yamaha NS-10's.

March 23 update:

I had a good long session with these speakers through a Single Ended tube amp, and these speakers really do sound fantastic, the front to back imaging is spot on and they cover the mid range perfectly. This is a great little speaker for tight space and is one I would seek out on a regular basis.