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 ...

Altec Lansing ACS33 (2.1 for PC)

Although not really hifi, having a set of decent sounding speakers for the PC does help when you are listening to MP3, watching movies, accessing Youtube, etc - especially when you are used to a decent sound system!

I choose the Altec Lansing ACS33 (2.1) many years ago as I could not convince myself to invest on a pair of nice Klipsch speakers for the PC ($700+ vs about S$135 for the ACS33)!

ACS33 2.1 PC speakers

In stock form, sounds leans toward bass and can sound boomy. Details and highs were acceptable.

Hence I decided to investigate possibilities on improving the ACS33.

With bottom half of the sub uncovered

I removed 6 screws  from the bottom of the sub to reveal the above pix.

Closeup of PCB (after substitution)

Perform the following on the PCB:

• replace the 1uF EC with a poly (yellow)
• replace non-essential 1uF with poly (orange)
• replaced 4x0.22uF (green) poly with 0.15uF Vishay BC (grey) - makes largest audioble difference
• replaced the 2 caps for filtering power supply with Rubycon 2,200uF
• add a heatsink to the voltage regulator as it gets hot
• changed a few caps on the right side of the pix (though not really necessary)

The results?

Bass was firm and quite respectable. High and mids sound pretty decent (to myself)! Don't think I will be shopping for a replacement anytime soon...

Sansui AU-7900

The AU-7900 is a well known unit in the "black face" line-up of the 70's. Perhaps best known for it's great phono stage.

A feedback at http://www.diyaudio.com/forums/solid-state/97232-sansui-intergrated-amp-su-7900-a.html speaks volumes of the AU-7900, especially since it was in a shoot-out by a stereo club!

Front

Internals from top

From bottom

Frankly I was quite surprised by the "kick" from the unit - at the volume setting in the pix, it had enough juice to drive the Mission 753 Freedom to a decent volume - many articles mention the 753 can be power hungry!

No recapping necessary as it still sounds great after all these years! Quality really stood out for something in the 70's.

Mission 753 Freedom

I finally laid my hands on the infamous unit. Weighting in at about 25kg each, it is a well constructed speaker.

753 without cover. Meridian A500 (with puppet on top), Quad ESL Pro63 in the rear and the Technics Honeycomb 

Upon initial listening using the copper cable transferred from the Technics Honeycomb, the 753 was disappointing - sounding compressed, glimpse of imaging, restricted headroom, with plentiful of flabby bass???

I was driving it using the Leak Delta 30 with only 15W RMS per channel but enough to drive my other well known speakers ... (not tried the Leak on my stored Celestion SL6s and the Pro63 yet)

Searching the internet, there were many comments regarding using an amp of atleast 50W per channel as well as mods to the crossover, etc to get the best from the 753.

What I did note was that the above setup while had plentiful bass and sounding compress, the 753 did convey the details as per my other speakers.

Hence I decided to try a simple experiment before going for the "works". I replaced the existing copper cables with my old QED Silver Anniversary (newer version has less than half the original core size).

Sounds almost top flight via the low wattage Leak Delta 30 using QED Silver Anniversary speaker cables!!! Like night and day by just changing the speaker cables.


Update

On the following week I managed to add a Sansui AU-7900 to my collection.

Tried pairing it with the 753 via the copper cable (since it has more power than the Leak). Bass was respectable but over-emphasized. The treble had the 'behind the veil'effect. Hence I inserted a bypass using a ROE 0.022uF for the 10uF and 6.8uF capacitor. And insert WIMA 0.33uF bypass for the 470uF capacitors. Furthermore added 2 layers of foam padding to the bottom cavity as the original was empty(?).

The cross-over unit looks a bit different from the pix(s) on DIYAUDIO and other websites as this is the Freedom model - without the 1,000uF capacitors and a simplified crossover board.

Original

After adding bypass to capacitors

Different view of cross-overs

Add 2 layers of foam

Speaker cable from the AU-7900 - more than enough 'juice'to drive the 753F

Been an hour and the sound is beginning to take shape ... vocals are sweeter and bass is firmer. Has the makings of a keeper!


Update:

Using the previous setup and copper wires, the 753F seem to slightly warmish. Bass became more firmer, voices were almost "being there" but there seem to be a very light veil still in-place.

Connecting the 753F via QED Silver Anniversary seems to be it. Everything is falling into place, with firm bass!!

Quad 33 (1st unit of 2)

This particular Quad 33 is part of components from my 1st set of Quad 33, 303 and FM3.

Updates completed were largely according to Dada Electronic suggestions. Electrolytic capacitors used were mainly average quality. Very few Wima and Panasonic FC were deployed. Sounds suprisingly good though.

Front

Bottom and rear

The original plastic feet were replaced by rubberised equivalents, to prevent impacting other components during stacking.

Phono and Tape board

Top view

A bypass was added to the output boards as there was not much improvement in the HF response e.g seem to have been "cut-off". Used a green Wima for the bypass on the output boards. Sounded proper again after the bypass was added.

I was more adventourous with the 2nd Quad 33.

Luxman T-240

This is the Luxman tuner which is of the same series as per my L-410.

Front

In stock form, the unit sounded nice but (a little) reserve. Due to age, the four power caps of 47uF 50V were replaced with 220uF 50V.

The following section were recapped with better quality capacitors - for the FM outputs.

Mod to FM output section

And the original 1,000uF 6.3V Elna cap was replaced with a Panasonic FC of equivalent specifications.

Sounds more open and realistic after the above recap. One of my visitors was pleasantly surprised when the FM station announcer did his job!!!

Accuphase E-203

The E-203 is an early Accuphase which help Accuphase established themselves.

The unit runs hot as it is a MOSFET unit based into Class-A. More details at http://www.accuphase.com/cat/e-203en.pdf

Apologies as I do not have pix of the internals, as the unit is still in storage at the moment. The unit is well known to have an excellent phono stage - MM and MC.

Front of E-203

E203 as pre with Meridian 557

Sugden C51 (***Updated***)

The C51 pre-amp, together with the P51 formed the reference set for many reviewers in the 70's.

Sounds pretty good, even by today's standards. It is a very simple unit internally - apologies as I located these two pix in a photo album.

I will add the P51 pix to the blog once I find it in my store room (no kidding!!!).

There is a site dedicated to Sugden components so I won't repeat the praises sung there.

Front

Rear

Update

The following are the internals of the C51.

Top View

Bottom view

Was unable to locate the special grey-ish DIN cable which carries the audio signal and power between the C51 and P51 to enjoy the units . . ... the joys of having too many items in the storeroom!!!

Sony ST-S333ESXII

This is my Sony ES tuner. It is to be part of my set of matching components with wooden side panels. The other units in the group are the Sony CDP-X7ESD, Sansui AU-G90X and Marantz CDA-94. The other maching tuner is the Sansui TU-D99X.

Quality is as per expectations from a ES component e.g Nichicon Muse, Elna Starget, etc.

Sounds pretty decent - as good as reproduction from CD!

The website, FMTUNERINFO rates the ST-S333ESXII well and I quote .... "the ST-S333ESXII is a really close second to the Macs in sound quality, and just as good as the McIntosh MX 117"

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Rear

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Left

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