Amplifier circuits

[drummerman]

I enjoy looking at 'lid off' pictures of amplifiers, cdp's etc. Even with todays double sided boards it's sometimes possible to trace the circuitry from beginning to end ... powersupply to output. It also reveals manufacturers design philosophy and sometimes trows up questions. Any of you feel the same?

I start with a Supernait. Look out for the meticulous wiring and relative 'simplicity' of layout. A large toroidal transformer and 2 sizeable reservoir caps/channel for a relatively low rated output in typical Naim fashion. Questions? Perhaps the close proximity of one pair of speaker terminals to the power line input?

 

[Anonymous]

On a not too dissimilar theme, I've read that the new Audiolab DAC contains 250,000uF of capacitors. That's a lot of charge when you consider that my Quad power amp has 40,000uF of caps for output of up to 20A peak current (100W per channel). It's comparing apples with oranges but still, a lot of charge!

 

[drummerman]

igglebert:On a not too dissimilar theme, I've read that the new Audiolab DAC contains 250,000uF of capacitors. That's a lot of charge when you consider that my Quad power amp has 40,000uF of caps for output of up to 20A peak current (100W per channel). It's comparing apples with oranges but still, a lot of charge!

 

[the record spot]

My one (not the actual, but as near as); those four big capacitors handle 15,000uF each, 60,000uF all in - mind yer fingers! - dual mono design too, ALPS pot, superb in its day and still now:-

 

[drummerman]

That looks impressive even by modern standards though it's difficult to make out from the picture what is where. Is the pre-amp board/circuitry next to the transformers or between the heatsinks/elsewhere? How old is the amp? (Spring clip terminals/captive lead)

 

[drummerman]

Primare i30

Looks neat. I can't make out if the volume control is of the processor type or a pot.

 

[the record spot]

It's from around 1977 (mine was from November 77 I think, going by the serial number), everything else, I couldn't say. I've had the lid off mine though I haven't tinkered; I'm no electrician, probably a good thing! I might take some shots of the interior now since the servicing earlier this year.

The front panel is shielded by that heavy casing, so accessing it becomes tricky. Needs - ideally - someone with experience, but these are few and far between in the UK. All the circuitry sits on its side as you can see, so it becomes a challenge to take it to bits.

There is a very good site on the web that details the stripping down process and the effort needed to do it properly. Mind you, when it is all done, it's 18 kilos of sheer joy; I'll run this thing till it finally gives up the ghost!

 

[chebby]

Luxman 550 AII

Yamaha A-S2000

Accuphase E-560

 

[drummerman]

Roksan Caspian M2/Kandy K2

 

[Anonymous]

RS: that's a thing of beauty. Drummerman: I don't know how to upload pictures, but I love the inside of the reference series Pioneers (e.g. A-656).

 

[drummerman]

Jack White:RS: that's a thing of beauty. Drummerman: I don't know how to upload pictures, but I love the inside of the reference series Pioneers (e.g. A-656).

Find a picture, right click, go to properties, hightlight URL right click and copy. When you compose your message click on the tree, paste your image URL and insert. I think max dimensions are 400 x 400 but not sure) or you can just copy the link as per chebby.

 

[Anonymous]

Thanks Drummerman, here it is (freshly nicked from the web):

 

[jockey.wilson]

drummerman:

I enjoy looking at 'lid off' pictures of amplifiers, cdp's etc. Even with todays double sided boards it's sometimes possible to trace the circuitry from beginning to end ... powersupply to output. It also reveals manufacturers design philosophy and sometimes trows up questions. Any of you feel the same?

I start with a Supernait. Look out for the meticulous wiring and relative 'simplicity' of layout. A large toroidal transformer and 2 sizeable reservoir caps/channel for a relatively low rated output in typical Naim fashion. Questions? Perhaps the close proximity of one pair of speaker terminals to the power line input?

Sorry to be a bit picky, but thats an XS not Supernait. Note lack of balance control and digital circuit. That said, the power supply transformer (Toroidal doughnut shape thing) looks very similar. In many respects, the quality of an amp is proportional to the size/quality of its power supply.

 

[drummerman]

jockey.wilson:

Sorry to be a bit picky, but thats an XS not Supernait. Note lack of balance control and digital circuit. That said, the power supply transformer (Toroidal doughnut shape thing) looks very similar. In many respects, the quality of an amp is proportional to the size/quality of its power supply.

Embarrassing. I'll see if I can find one of a SNait. Here it is ...

 

[MUSICRAFT]

the record spot:My one (not the actual, but as near as); those four big capacitors handle 15,000uF each, 60,000uF all in - mind yer fingers! - dual mono design too, ALPS pot, superb in its day and still now:-

Hi the record spot

The Sansui is beautiful

Old is gold

All the best

Rick @ Musicraft

 

[the record spot]

Jack & Rick - thanks very kindly. My take on this amp is really simple - if you see one, buy it. Chances are you'll get one for about £200 (ignore Audio Gold in Crouch End in London who have a D907F - effectively a 919 I think - for £500, this is hopelessly overpriced) and you won't look back. Best thing is, you can add a power amp to one of these...

 

[the record spot]

And I should add that Jack's Pioneer looks the business - shortlisted that one for, er, "future reference" on a just in case basis!