January 2024 Meeting - Member Gear - B&W DM220 +

[masterpaul]

Dear members and friends of Sydney Audio Club Inc,     
     
The first Club meeting for 2024 will be held on Sunday 21st January with a presentation of some classic vintage equipment.

The doors will be open from around 1.00 pm to meet and chat with members before the meeting starts at 2.00 pm.

There will be no Techtalk this month.

Guests are welcome – we are a very friendly club so you don't need to know anyone to join us for an afternoon of fine music and sound.
   
Details of the system for January 21:    
Speakers:
Bowers & Wilkins DM220 from around 1984 - two pairs stacked vertically.
They are a 3-speaker 3-way sealed bookshelf design handling up to 100 Watts into 8Ω with a frequency response from 53 Hz to 20 kHz ± 3 db.
Output sound pressure level 90dB/W/m
Crossover frequency 500 Hz, 3 kHz
External dimensions Width 290 x Height 680 x Depth 320 mm
Weight 15.1kg
Two 20 cm cone type woofers are mounted in the low range and drive the band of 500 Hz or less in parallel.
A fiber cone is used for the diaphragm, and high efficiency and excellent transient characteristics are obtained by driving with a strong magnetic circuit while aiming at low mass.

In addition, the roll-off characteristics of the unit itself match those of the secondary Butterworth filter, and by simply passing the secondary Butterworth filter through one stage, the characteristics of the fourth Butterworth filter (24dB/oct) are reasonably realized. This gives ideal slope characteristics, and by realizing steep attenuation characteristics at the crossover point, interference to the high range of the woofer is effectively suppressed.

A 2.6 cm soft dome type tweeter is installed in the high range.
The diaphragm is made of polyamide film, which has high internal loss and low high-frequency resonance, enabling natural and accurate high-frequency reproduction.

 

Amplifier:
We have two amplifiers to choose from and possibly compare.
 
Audiolab 8000P Stereo Power Amplifier
Power output: 100 watts per channel into 8Ω (stereo)
Total harmonic distortion: 0.05%
Signal to noise ratio: 95dB
The Audiolab 8000P Stereo Power Amplifier is a vastly underrated amplifier. The 8000P was loved by many but also hated by a few others. The main criticism being that it could sound a little sterile, where as those people that loved the Audiolab 8000P Stereo Power Amplifier pointed to it's excellent imaging and bass.

 

Pioneer SA-7500 Amplifier
Power output: 45 watts RMS per channel into 8Ω (stereo)
The Power Amplifier section uses 1-stage differential amplifiers direct coupled OCL
Outputs: A, B and A + B
The Preamplifier section Equalizer is 3-stage direct-coupled and the Control amplifier is 2-stage direct-coupled with 1 FET, NFB type.
Total harmonic distortion: 20Hz – 20kHz no more than 0.05%
This amplifier has independent Bass and Treble controls with Loudness, Hum and Noise filters – remember those !!

 

DAC:  
Topping D30Pro Pre-Amp DAC
The Topping D30 Pro is a quad-CS43198 chipset desktop DAC with preamp capability offering up to DSD256 and PCM 32BIT/386kHz decoding
USB support DSD256 & PCM384kHz high resolution audio
D30Pro uses 2nd generation 8 core XMOS XU208, USB supports up to PCM32bit 384kHz and DSD256 native.
 
Universal Blu-Ray Player
 Reavon UBR-X200 UHD Universal Blu-Ray Player purchased by our club with the generous assistance of Len Wallis Audio.
https://reavon.com/bluray-player-ubr-x200/

 

The second half of the music session is designed to help you evaluate the system with music that you are familiar with. All members and guests are welcome to offer music to share with us all. So bring along your favourite music to play on CD or USB only – no streaming or vinyl this session.
All we ask is that the music and recordings be interesting. We'll ask you to tell us a little about the artist/recording before it is played. Tracks over 6 minutes will be faded out, to give everyone a fair go. We will also have a club member act as Disc Jockey for this session.   

 

Whether you are a novice or a seasoned veteran, you will have the opportunity to listen, learn and share your experiences with others. Feel free to come and hear the capabilities of the system, or to just share the experience with like-minded music lovers in a friendly and relaxed atmosphere.

Guests are welcome – we are a very friendly club so you don't need to know anyone to join us for an afternoon of fine music and sound.  
 
Please bring your music to share with other club members.  

Venue:  Mathews Room, Epping Creative Centre, Dence Park    
Address:  26 Stanley Road, Epping    
When:  Sunday 21st January 2024.

Doors open from 1.00 pm to meet and chat with members.  
Meeting finishes at 5pm with an afternoon tea break.
    
It is a requirement of entry that you sign-in in the visitors’ book.
You are not required to wear a mask but you may wish to do so.    
    
Hope to see you there on Sunday 21st.

John McEvoy
Meeting Co-ordinator
Sydney Audio Club Inc.  
w: www.sydneyaudioclub.org
e: enquiries@sydneyaudioclub.org.au
f:  www.facebook.com/sydneyaudioclub

[A.K.]

A very well attended meeting (for January) and,  we were pleased to see / meet four new guests,  very encouraging!

 

In the first half we were hosted by James who presented music through his pride and joy, the Pioneer SA-7500, a 'gem' and very sought out integrated amplifier from times gone by.

It can still hold its own, against modern amplification as it became evident after listening to it.

 

The four B & W DM220 Speakers were stacked in a column, the top one in an upside down manner, in order to simulate the D'appolito configuration used in many designs, where the twitter(s) are positioned between the midrange drivers for a more coherent sound.

 

James had them working in parallel top and bottom, ( a brave man!..) which had the amplifier "seeing" a 4 Ohm load at best, which could drop as low as 2 Ohm (or lower) at some frequencies!

Yet, the session went well without any incidents and the Pioneer proved to be more than capable in such configuration, despite its modest power output, and at sensible levels.

 

After the coffee brake, the system changed to a Bi-Amping configuration, with two power amplifiers available.

 

The Audiolab 8000 P (https://audio-database.com/AUDIOLAB/amp/8000p.html),  and a Meridian 556, (http://www.meridian-audio.info/public/556[78].pdf), both at 100 w / 8 Ohm per channel.

The Audiolab drove the two bottom speakers while the Meridian was connected to the stacked top ones.

 

This configuration allowed the speakers to operate (mostly) at their 8 Ohm nominal impedance, each having access to 100 watts (if required) from the two separate amplifiers.

 

James was kind enough to continue presenting the "brink your own" session of the meeting.

 

The sound now was  (understandably) more effortless and somewhat more dynamic although some of the sweetness of the Pioneer was lost.

Instead, a very clear, clean and detailed sound emerged as a result of the two large amplifiers working independently on each pair of speakers.

 

The Audiolab 8000 P and the Meridian 556  amps are known about giving an uncolored and 'matter of fact' sound. 

 

Overall this combination offered a more punchy sound with well controlled bass notes and plenty of detail.

By the end of it, it became clear these B & W speakers are anything but 'obsolete'!  

Perhaps we need to re-think about vintage components and their capabilities....

 

And so, the afternoon  went smoothly, with many satisfied listeners that were encouraged to fill the provided new forms of feedback,  with levels of satisfaction as well as, suggestions and new ideas.

The 'feedback'  form is an important part of member participation, in allowing the committee to evaluate opinions and form a path for the future.

So, please in future meetings, make an effort to fill one of these forms to assist with this project.

 

My (and that of the committee)  sincere thanks to James and Ian for supplying and presenting their treasured toys, the Pioneer SA-7500 integrated amplifier and B & W DM220 speakers

Vey well done guys!

 

Till Februray then!

 

 

[masterpaul]

We can't always obtain the latest and greatest for every meeting, so occasionally we ask members to present equipment.

 

On Sunday 21st we had an opportunity to audition 'stacked speakers' for ourselves and see if the concept "stacks up".

 

This presents some technical problems.

Although the speakers were rated as 8 Ohm nominal impedance, some searching revealed that dual woofer systems may drop to 4 Ohms or less at some frequencies - typically between 100 ~ 1000 Hz - and where the most power is required.

For most competent amplifiers this is not a problem however wiring two of these speakers in parallel means impedance could drop to 2 Ohms or less.

 

For the first part of the meeting two speaker pairs were connected in parallel to the Pioneer amp.

The sound was both entertaining and wildly inaccurate.
We learned later that the amp was being run with the loudness switched on and bass boost on the tone control.

 

For the second half two power amps were used, one amp for each pair and fed directly from the Topping DAC.

Unfortunately it wasn't possible to find two identical power amps at short notice.
This presented a different issue as although the two amps had the same rated power and similar topology the input sensitivity was different by something like 3 ~ 4 dB.

Each amplifier was 100 WRMS PCh but somehow the Meridian 556 was the 'sweeter' of the two.

 

The USB source was somewhat gritty and harsh, the CD transport source was superior.
I suspect there was some interaction between the music software (Foobar 2000) and the Windows audio settings - see images below.

 

We did try one pair of speakers on their own and this had superior clarity to the stacked pairs.

There was speculation as to whether there was acoustic interference in the stacked configuration or differences in the amplifiers smearing the sound.

On the plus side the system filled the whole room effortlessly.

 

Two highlights -
"Tricycle" by Flim & the BBs, 1989 DMP Digital Music Products, and
Grofé: "Grand Canyon Suite, Cloudburst" Telarc

No one has ever accused Telarc of being too subtle, and it was abundantly clear that there was 400 WRMS on tap.

 

Great fun.

[masterpaul]

Since the meeting I have found out that the DM220s use 16 Ohm woofers wired in parallel, so no impedance issues running both pairs from a single source.
However Prof. JL had modified the crossovers in one pair and not the other which accounts for the different sound of one pair vs the other, as detected by a few of our more astute members.

[A.K.]

LOL!  Well spotted  Paul..

Mods need to be equal to both sets of speakers, otherwise one enters a .... minefield (of sound).

Personally, I was tricked in believing that the two different amplifiers used (when bi-amped) were the cause as, the Audiolab 8000P  and the Meridian 556 are voiced quite differently.

Of course, when used working in parallel with different crossover specs, it could create an audio havoc.

Yet, I enjoyed the experiment!

 

[Badjones]

I know nothing of technical details, but was interested on seeing some DM220's being tested. I have a couple of pairs of these speakers and have had plenty of surprised positive comments from people hearing them driven with a Yamaha 80WRMS amp. I have the factory stands and find that they love being on those for some reason. I'm looking at some new B&W's but its hard to replace these great old speakers.