Sugden P51

Yes I finally located the P51 in the storeroom!!!

The P51 is the power amp which accompanies the C51 pre.

Weighing about 10kg, the unit is able to deliver 50W RMS per channel and had the innovative feature of being able to be converted into a mono-block with the flick of a switch (for the 60's).

The P51 is known to be able to drive extremely demanding loads and many often used them with ESL(s).

In addition, the C51-P51 pair was often the reference set for many reviewers in the late 60's and early 70's.

Front

Back

Top

Right side

Left side

The last time I fired up the C51 with P51, reproduction clearity was startling - when you consider the age of the unit.

Need to locate the special DIN cable which came with it ... one of the joys of having too many units and managing the misc cablings for them!!!

Speaker cables I am using

Please note I understand there are many opinions and preferences in this area. I am not implying in any manner or form, if any make or model of speaker cables is better than the other, or, even attempting to rate them. 

I am only advising this is what I am using to connect the various units in my collection of speakers and amps aka this is what works for me

The next question my visitors frequently ask after checking out my various speakers are (pix in Mission 753 link below) ... what speaker cables are you using? once they have heard my setup, and, noted the various well known speakers I have in my listening area.


The following is a close-up of the thin-nish speaker cables I am using.

Closeup of speaker cables from the Sansui AU-7900

You can see them deployed in the pix(s) for the Mission 753  at http://myoldvintagehifi.blogspot.com/2011/01/mission-753-freedom.html, Meridian A500  at http://myoldvintagehifi.blogspot.com/2011/02/meridian-a500.html and Sansui AU-7900 at http://myoldvintagehifi.blogspot.com/2011/01/sansui-au-7900.html

Any guesses? If someone gets it right, I will spill the beans and reveal how I acquire them. 

Been using these speaker cables since 2004 for my Celestion SL6s, Quad PRO63, Meridian A500 and Technics SB-X700. I have a large box of well known brands of speaker cables in my storeroom - been there in the storeroom since I started using the above cables. Only took out the QED Silver Anniversary for the Mission 753 recently - can't recall when was the last occassion I used it before this!

Sssshh to my visitors who know the answer ... please don't tell them yet !!!

Meridian A500

My visitors often ask about my unbranded speakers (logo not visible from front) once they hear it. My usual response is  "... don't worry just enjoy the music".

View from sofa

Curiosity usually gets the best of them after about 5-10mins .  . . 

Angled view

Rear

Rear

Top

Frequent reactions upon eye-ing the well known logo include these for real?, how old are they?, where did you get them from?, and, don't remember this model?

The A500 was the last passive model speaker from Meridian e.g mid 90's. Judging from my visitor responses of the reproduction, one can easily imagine why the model is rarely available in the resale market.

Removing the sock (aka dust cover) reveals the two 6-inch units for mid and bass. Treble is provided by a horn loaded tweeter. Each speaker weights 25kg.

Without sock

Sock for speaker

Although rated at 90dB with maximum wattage of 100W, it is a surprisingly power hungry unit. I was using the Celestion SL6s (well known power hungry model) paired with a 100W subwoofer before switching to the A500. The SL6s were rated at 86dB and 120W. I expected the volume to increase after the swap. Received a most nasty shock as I had to turn the volume up a little more from the same setup, to obtain the volume as per the SL6s when using the A500!!!

From experience the A500 is at it's best when driven in a horizontal bi-amp mode. Bass is then superbly firm and sounds extremely realistic. High power amps are required to do so. Otherwise you will hear the polite bass, as per hifi reviews from the past. I previously used a pair of Arcam Alpha 8 power amps (50W RMS per channel; my mistake to use the newly recapped Sansui AU-5900 as pre-amp!!! Buyer wanted that as well)  for the task. Sold the Arcams as they were hardly used once I had my Sansui B-2101 and Sansui B-2102 power amps recapped since these were more capable (each rated at 200W RMS per channel).

Another unique feature is the method to re-sock the speaker. There are no pugs or pins to hold the sock in-place. Instead the grooves towards the front of the speaker are the holders. These grooves run the entire front parameter of the unit. Once you place the sock into them, you need to use a credit card (or similar plastic item) to push the sock firmly back into place.

Before "sock-ing"

"Sock-ing"

The base of the speaker has four spikes which are adjustable. My A500 was adjusted to be just slightly higher on the front than rear to permit better image projection nearby.

The original boxes for the A500 now store my SL6s.

Quad 33 (2nd set; ***Updated***)

After the conservative and successful maintainence to my 1st unit, I became more adventurous.

Top view of the 2nd unit

As per the 1st unit, voltage was increased to 16V following Dada Electronics suggestions. I replaced other capacitors in the unit with Wima, ROE,Philips for poly and EC are Panasonic ECA, FC and Rubycon. Poly caps were replaced in the motherboard of the Quad 33 as well, using ROE and Wima.

All value of the new capacitors are as per original except the large Wima used on the tape monitor board (immediate below). Found the 1.5uF MKS-C (replacing a 2.2uF electrolytic capacitor) to be most suitable, resulting in solid and realistic bass reproductions when partner-ed with my 2nd Quad 303 (http://myoldvintagehifi.blogspot.com/2010/12/quad-303-after-recapping-2nd-unit.html) driving the Meridian A500.

Phono and Tape adapters

Another view of the Phono and Tape adapters

Pre-amp adapter boards removed to show mainboard substitutions 

Closer view of the exposed mainboard

One of the pre-amp boards

Back of the pre-amp board with bypass

Phono board

Back of  Phono board with bypass

How do these Quad 33 sound and compare against the original?

Both of the original units were warm but sounding as if they hit a treble ceiling (aka roll-off). Bass was not boomy but neither was it firm. Reproduction of details from the original were acceptable but not superb - reveals much potential. 

After performing maintainence to the 1st Quad 33 unit, it sounds mellow with good reproduction of the background details. The 2nd unit builds upon the1st unit's capabilities with highly improved headroom and much firmer bass when paired with the maintained Quad 303.

The Quad 33 and 303 are well worth preserving as these were well designed with ease of maintain in mind.


Update - 15Nov2012

Bought some ERO KC1849 a while back but did not have the time to install them into my units.

Hence finally had the opportunity to insert four 0.01uF onto the Phono adapter board, replacing the blue Wima(s) of equivalent values.

After ERO replaced the blue Wima

So far so good ...