Millenium 4-20 (Maplin Electronics)

[Dave Ed]

I'm beginning to realise that now

[leesonic]

I came across this site searching for information on the Maplin Millenium (see my introduction post at) :

http://www.wduk.worldomain.net/forum...85&postcount=1

I have the original articles for both the Millenium power amp, and the Newton pre-amp. I'd love to dip my proverbial toe in the water of valve amps, but in my recent visits back home, Maplin seem to have moved away from their electronics background, they only appear to stock Velleman kits now.

Is it still possible to get PCBs for either the Millenium power or Newton pre-amp? The original articles for the Newton don't show a PCB track layout, although with some Paintshop Pro work it should be possible to make one. I've never made a PCB before, so that will be an investment in the etchant, drills etc. Failing that, I've seen some people wishing to strip wire their existing amps, any layouts for that?

Then there's the question of transformers, I'm sure Maplin no longer stock them. Doing my research there are a couple of companies here in the States that make valve (tube) transformers. From the original article, the output transformer specs are 6.6k with 43% from CT screen grid taps. Can anyone suggest suitable output and power supply transformers from these companies?

http://www.edcorusa.com/products/tra...push-pull.html
http://www.hammondmfg.com/5cindex.htm

The Maplin design used silicon rectifiers. Has anyone re-designed their Maplin amps, Millenium or Newton, to use valve rectifiers? Something big like a 5U4 would look good in the Millenium, it might even dwarf the EL84s. Maybe something like a UY85 in the Newton. I saw in an earlier post that someone modified their Millenium to use KT88s. Was there any circuit or transformer modification needed for those valves?

So many questions I know. But I'm new here, and if you don't ask you don't find things out.

Lee.

[pre65]

You have a PM Lee.

[pre65]

Maplin still do this output transformer and it looks half tidy !

http://www.maplin.co.uk/module.aspx?moduleno=46773

Andrew I purchased a pair and he said they looked OK ! Don't think he's used them yet though.

[pre65]

Try and get a copy of the Mullard book "tube circuits for audio amplifiers" and study the chapter on the 20W amplifier.

This goes into great detail to explain the famous 5-20 amp build,and of which,the Maplin millenium was a cheap(ish) copy !

This has the valve rectifier and a pair of EL34 in push pull.(per monoblock)

There is one on e-bay (USA) at the moment.

http://cgi.ebay.co.uk/Mullard-Tube-C...3A1|240%3A1318

A VERY worthwhile read if that is the sort of amp you aspire to,and with full specifications and component values.

PS 4-20 = 4 valves @ 20W
5-20 = 5 valves @ 20W (the "extra" valve is the rectifier,or rectumfrier)

[Mike H]

Originally Posted by leesonic

I came across this site searching for information on the Maplin Millenium (see my introduction post at) :

Is it still possible to get PCBs for either the Millenium power or Newton pre-amp?

No, not for about 10 years

Then there's the question of transformers, I'm sure Maplin no longer stock them.

No, I do!

The Maplin design used silicon rectifiers. Has anyone re-designed their Maplin amps, Millenium or Newton, to use valve rectifiers? Something big like a 5U4 would look good in the Millenium, it might even dwarf the EL84s.

Yes, originally U54 probably, might still get it as NOS. Else GZ34, that works too

I saw in an earlier post that someone modified their Millenium to use KT88s. Was there any circuit or transformer modification needed for those valves?

Depends, if the idea was for more power, then definitely different

Originally Posted by pre65

Maplin still do this output transformer and it looks half tidy !

That is NOT the same transformer as was originally created for the Millennium, Maplin discontinued all those

[Mike H]

Originally Posted by leesonic

but in my recent visits back home, Maplin seem to have moved away from their electronics background, they only appear to stock Velleman kits now.

That's right, they were down-sized and the whole shebang moved up to Yorkshire. In the process they lost the in-house development engineers 'lab' to design new projects. The original South East head office finally closed about 2001 I think. Without the 'lab' kits couldn't be kept up to date and trouble-shooted. To be honest they wanted to dump kits anyway cos they are a big hassle to maintain and by that time they become largely controlled by the bank cos they were in financial difficulties. The bank bosses insisted on streamlining, I'm guessing. Maplin have now become like a 'Tandy Store' which I think was the best solution TBH. Also the number of home constructors was waning (a survey was done once I remember), only ones left wanting to actually build stuff seem to be 'old fogies' like me; the younger generation just weren't interested.

Sorry if these posts seem a bit downbeat

[Mike H]

Aaaaaanyway, on a somewhat brighter note, here's some photos of my still ongoing Millennium Mk II prototype

[Mike H]

[leesonic]

Originally Posted by Mike H

(5U4) Yes, originally U54 probably, might still get it as NOS. Else GZ34, that works too

Theres a site I use a lot over here in the US called parts-express (www.parts-express.com). They still have a 5U4 rectifier tube listed, two actually, when I just checked their web site, they were out of stock of the Sovtek, but had the Electro-Harmonix in stock. Maybe certain valves are easier to come by in certain Countries?

For those of you in London, did you ever visit an electronics shop called Garlands down at the bottom of Blackheath Hill in Deptford? As a kid, I used to go there a lot, in fact, that was where I bought the SEAS drivers for my "monster" speakers (see my introduction post). They used a stock a range of Mullard and then later Pinnacle valves.

Originally Posted by Mike H

(Maplin) That's right, they were down-sized and the whole shebang moved up to Yorkshire.

That's a real shame. I've nothing against Yorkshire, but when they were in Essex, I could order one day, and the stuff would be at my house the next. In fact one day, I ordered in the morning, and it was there when I got home from work.

Parts Express have that Mullard book in stock, I will have to add it to my cart (American for trolley) when I place an order next.

Lee.