Toshiba SB-420 Stereo Amplifier

A really beautiful amplifier and the matching tuner is equally nice. I believe these were produced around 1974-77 but I have been able to find little info on them.

 

The ST-420 tuner is a lovely piece of design, I especially like those linear meters for the Signal strength and Tuning centre. The way the tuning scale fills the width of the unit and the angled front panel makes it my favourite tuner to date.



I'm very impressed by the build quality, If these had a Pioneer badge they would fetch silly money but it seems these Toshiba units have slipped through the net. The PCBs are marked Aurex which only appears on Toshiba's high end offerings. Two 10000uf capacitors in the amplifier power supply, no twin transformers here but the transformer is very big for a 40watt amp.



I was given this amp by a friend who said it had a nasty crackle on one channel that was un-effected by operation of the control knobs. When I tested the amp with my headphones, I nearly went deaf from the huge pops and bangs it made. I quickly turned it off and started tracking down the source of the noise.



I am convinced the issue is coming from the RIGHT channel on the tone control board "CCT-AF-C51". The noise is like the wind blowing, with random pops and bangs, I assume this is a transistor at fault?



I've found the service manual via a thread on audiokarma and upon close inspection I can only assume that Tr009, Tr0011 and Tr0013 are the cause of my still ringing ears! Also C031 had exploded which I'm guessing may have caused the fault?

I could really use some help in trying to resolve this issue. I don't know if I'm attacking the right components and if I am, what would be suitable replacements?

A Google search suggests NTE159 PNP for 2SA841-GR and NTE199 NPN for 2SC1000-GR but is this correct for my application and are there others I could use? If you are reading this and could give me some advise I'd be forever grateful.

On the schematic TR009, TR011 are marked 2SA493-GR but appear as 2SA841-GR in the parts list and in real life. Maybe a 2SA493-GR would also work here?

Anyway the sound of the one working channel suggests very decent sound indeed, with very good bass performance and a mid-range bursting with mustard. The top end however is a little foggy but the power amplifier is still waiting for a re-cap.

If you can help, please don't hesitate to get in touch via the comment box. Until the next time guys...

Pro-Ject Head-Box - The Amazing Headphone Amplifier

Not really vintage but an interesting little box nevertheless. I have little experience with headphone amplifiers, even headphones in general but this unit was very surprising indeed.



I picked this up at a boot fair a few years back and its just sat around in a cardboard box ever since. However the other day I was refurbishing my cherished Cambridge CD1 and felt the need to go hunting for op-amps. This lead me to the Pro-Ject Head Box but sadly it used dual op-amps, not what I was looking for. But upon opening the unit I was so impressed with its design I felt I should take a closer look.



I came across a thread where someone had also been impressed with it and modified theirs with great results. I could feel me figures twitching for the soldering iron, I wanted to get stuck in, it was Lampizator all over again!

I plugged the unit in for the first time and was shocked, it sounded better than my Sansui Ca-2000 on headphones! How can this be, my world has been crushed. Cheap and cheerful op-amps never sounded so good!


So lets gets started!

First off, new caps
470uf   35V   x2  main power supply, after ac-dc conversion
330uf   16V   x2  main power after regulator
10uf     63V   x2  op-amps (no need for such high voltage surely?)
4.7uf    100v  x4  decoupling (by volume pots)

Main power supply caps can be increased but I kept original values as space is at a premium and very little current drain in this amplifier. I used Sanyo oscon on op-amp and 1uf polyester for decoupling. The polyester are by no means the best thing to use but its all I had. Polypropylene should be used instead, wima ect.

Second, op-amp sockets for easy swapping!



Above we have the finished article, or so I thought. After plugging my phones in I had too much mid-range, very crisp and transparent but it was hurting my ears! Hmmm I felt the polyesters may have given this effect but I wasn't sure. So now I had to get those op-amps out and start swapping!

The 4580 came out and the LM833 went in, not much difference on paper but the 833 is used in a lot of the good old TDA1541 Philips players.

Headphones went in and BAM! there it was, perfect. The LM833 sounded lush, shimmery mid with very realistic vocals and as a bonus it had less distortion at higher levels. Anyone who says op-amps have no impact on sound is talking rubbish!

I had to play the whole London Grammer album, start to finish, I was helpless. So this is me signing off in a state of bliss, until the next time folks!

Quad 44 Pre-Amplifier & 405-2 Power Amplifier

A highly respected pair of units with a massive following. I have fond memories of my Quad 303 so I was hoping for more good things here.

Lets start off with the 44 pre-amp.
First off, I love the styling. The choice of colours is perfect and it's nice to see the tasteful use of LED indicators. Interesting control layout but of course we leave everything flat.

 

This is a very well built unit, face plate is cast metal which is then painted grey and brown, surely the two best 70s colours. Sadly a lack of inputs is a bit of an issue so unless you use din connectors you are limited to a Phono and Auxiliary input. However there is a good selection of input settings on the top and the pre-amp has two sets of outputs, one is louder than the other. The lower output worked best for me because that volume knob is sensitive!

 

On the whole I was a little disappointed with the quad, the sound was good but so serious, dark and solid. There was nothing to get excited about, and that baffled me. Why do so many people go after these things? I suppose they are a well known, good quality, reliable amplifier with decent power but for me nothing in the musical department. I opened up the pre-amp to find a nicely built modular layout. Good use of quality components as well, I was starting to like the quad again but It wasn't to last. What did I find?  nasty op-amps. Why Quad why! A pre-amp with op-amps in it and the 405.2 has them as well! Hence the dull and unengaging musical experience then.

I'm sure a full recap of the pre-amp and power amp will provide better results but after you workout the costs you may as well get a better setup. £400 - £500 on a good 44 405 pair, plus another £100 - £200 on recap. For that kind of money you could buy a pioneer sa-9800 or a Sasnui au-999 and you wont find op-amps in there. Better still, get an Optonica SM-3636, recap it and blow them all away for peanuts.

Untill the next time guys ;)

Sansui AU-9900

Pioneer SA-9500 mkII

Pioneer SA-9500 MKII Integrated Amplifier.





 



 

Sansui Ca-2000 Pre-amplifier & Ba-2000 Power-amplifier

The Sansui CA-2000 Control Amplifier.

Sansui had come a long way since they started as a small manufacture of transformers in 1947. By 1975 Sansui had introduced the CA-2000 and Ba-2000, this pre and power combo were slightly smaller than the 3000 series but what they lost in size they more than made up for with their elegant looks and lush styling.

 

Everything was silver at the time but the black and silver styling from Sansui remained and personally, I think it's far superior. Sansui were building some of the worlds finest audio equipment but sadly the company would later hit hard times and be lost for all eternity. That is until the very early 90's when they started to fight back but even though they had some good amplifiers they disappeared again. Now you can find their name on cheap lcd tvs and £10 dvd players.



The Sansui BA-2000 Base? Amplifier

Introduced alongside the Control Amplifier the 2000 amplifier was a great big hunk of 110watt solid state goodness. First class build quality, one huge toroidial transformer with two windings, one for each channel of the amplifier. Big vu meters on the front with selectable scale and they are back-light in that lush Sansui green.



The sound is sublime, its fairly warm and sounds so effortless. The Pre & Power combo is very "lush" sounding rather than "high-end" but, when mated with the right speakers, envelopes you, there is an overwhelming force making you tap ya foot, it seems only Sansui units have this "magic". I can play the same music on the same speakers but with a pioneer sa-9900 in the driving seat I feel nothing. No emotional response from the music, that is a serious negative and I shall be writing an article going into further detail soon.

By this point you may think I'm some sort of "Sansui FanBoy". Well, I am, but only because they have proven themselves worthy. Trio 600, Pioneer sa-9900, revox B750mkII, acuphase pre-power, the list goes on but nothing captures me in the music like these. I find the build quality exquisite, I really love the looks and the sound is sheer bliss. Sansui equipment has a serious fan base and all the high end amplifier models are well respected, Its just a shame their speakers don't deliver!

Luxman 308

The Luxman 308 Integrated amplifier.

Vintage solid state amplifier from the early 70's. 55watt rms a channel, tone controls for left and right. Perspective control and advanced filter controls. Made in Japan using the finest components of the time.