Millenium 4-20 (Maplin Electronics)

[Richard]

Yes, the Maplin metalfilms used to say Philips in the catalogue I think. Nice resistors, brighter and clearer than carbon films. Perhaps best not to stuff the whole amp with them (I did exactly that with a pair of Quad IIs ) as they can get tinkly bright but not gritty. Of course they might reveal rough valves (but not GEC KT66's).

If it's a bit gritty I'd look to the EL34s. Chelmer aren't a maker so they could be from various manufacturers. I had KEL34 for a few years (Mike's modified amp is looking very similar) and a pair of very nice monobloc 5-20s for a couple of years too. I love EL34's and will build another amp for them sometime unless WD bring one out

Best overall EL34 I found were Svet winged C sweet, open and neutral sounding. Bounciest were the big sounding fat bottle EI CA7s a little rough but great fun on rock. JJs are creamy smooth but a little closed in compared with the others. Some Chinese are sweet and there are new EH and Mullard branded ones now which I've not tried - but give the cheap small bottle EIs a swerve, probably not many around now.

Rich

[alnewall]

My old Millenium is built entirely of Maplin resistors and doesn't sound gritty to me. If anything it sounds a bit soft and woolly.

Richards views on EL34s, mirror mine exactly.
The new EH 6ca7 are good and in a similar vein to the EI tubes. I can happily listen to these for a change from the Svets.
EH EL34s are detailed but a bit devoid of emotion and uninteresting for my taste.
Shuguang are quite good but i find them a tad bass light.

[Victor]

Hi guys and girls,

I`m really impressed this post is still getting hits and replies. At the moment I have my maplin kit in the box keeping it safe. I`m renovating the house at the moment and also added wind and solar power etc.

If anyone is stuck for the diagrams or anything I can make a small website when I have time with the articles etc. I still have the magazines in perfect condition.

Anyway!! I`m impressed with the build quality and also the modifications people have done to this amp!! Some hate it some love it!! some improve it

I see it as the poor mans introduction to valve sound!

People forget that the Maplin engineers worked on this amp for a short time and not as much as other Valve companies that well...Sell high end kit!!

For what it was at the time was basically a re model and revamp of an off the shelve kit.

To add to the topic. There was also a pre amp made for this amplifier published before this millenium amp. I have not seen anyone who has made the matching pre amp to date. Personally mine sounds fine,but now listening to the modifications people are doing it might be beneficial to improve on the design!! Had a 3 way set of speakers on it for ages and the amp sounded good. I find mine lacks the bass but I really enjoy the midrange of this amp.

Its good in the high end too! Currently use a set of mission speakers on the system and they seem to sound better than the 3 way ones I was using.

To date I don`t think i`ll part with this amp for a good time yet. And for the little spent on it I feel it offers value for money for budding cnstructors.

Has anyone built or heard if the velleman kit valve amp is any good?


K4040
STEREO VALVE AMPLIFIER / CHROME VERSION
K4040B
STEREO VALVE AMPLIFIER / BLACK VERSION
K8010
MONO 65W PURE CLASS A VALVE POWER AMPLIFIER WITH KT88 VALVES

http://www.velleman.be

For now keep going with your upgrades and different styles of building this amp!! I really enjoy reading the new posts on this subject and have learned a lot from it.

[Dave Ed]

nice mid but treble can be a bit 'gritty'

Interesting that others don,t find this with their amps, mine is still 'under development'-Mike has suggested it could be an RF problem?

[Ianm2]

I have seen the pre schematic.

Its a cathode follower active line stage. ecc82

bass and treble active tone controls ecf80

interesting, I have only recently found out...

ef...pentode

ec triode

ecc double triode

ecf pentode, triode efc 80 is a combo I think of ef 86 and ecc83

el power pentode

ecl pentode, triode, ecl 82 is a combo of el84 and ecc83, wow....

fascinating eh?



and the mpalin pre's phonostage is v similar to the rca/gec one, using ecc83s, passive riaa and very stadard resistor values,

good attention as with th epower amp to the power supply....decoupling, stabilty compensatino, and grid stoppers.

these amps are really quite well designed indeed.

hats off to mike

tubes

again, I like the classic brit valves ecc81, 2, 3, 88, ef86, el84, el34 partic. I love. something about the sound, sadly mullard are the best and dearest.

best new is svet winged c, totally agree with rich.

EH aren't bad at all.

jj take it or leave, does the job., ditto sovtek/reflector.

bargain not too known is 5881, silly money, sounds good, v rugged. 6l6, not quite as good, but does the job.

valve art are superb, chinese, very very highly rec.d

I have a proposal for wad I think would work, may put it on a new post.

how about reissues, checking copyrite of course, about the classic amps

eg., mullard 5/10, 5/20,

ged praps,

williamson,

radford

scott or dynaco

and other classic goodies, these got it nigh on rite 1st time, I really don't think you can much improve on them.

they are great and quite simple

#and I WANT a 300b based preamp, but not sure how to configure the line driver.

I tihnk you may even be able to couple it resistor capacitor!!!!

[Richard]

Originally Posted by Dave Ed

nice mid but treble can be a bit 'gritty'

Interesting that others don,t find this with their amps, mine is still 'under development'-Mike has suggested it could be an RF problem?

Could be lots of things, maybe showing up shortcomings elsewhere in the system or simply that the new presentation is unfamiliar. Many folk love/hate EL34s for exactly this reason. Of all op valves they are perhaps the most colourful though they can be neutral with some work. Fantastic for rock/guitar/jazz

Many non-standard amps will work quite easily but you can spend a lot of time getting the best from them. This is where a good commercial amp (should) score, or building a well sorted kit, or established design with approved/tested components, gives benefits. Otherwise you need to be able to understand or see (scope) what's happening. All good fun but time consuming.

Can you scope it on square wave first to check it's not something fundamental? This circuit usually rings a bit but the amount depends on the quality of the op tx.

If you have different txs it's worth tweaking the hf feedback cap to suit them (using square wave). Also try lowering the amount of feedback which tends to make for a more open and involving sound and will improve stability. The circuit was something of a showcase for low distortion for Mullard at the time and has quite a lot of fb to achieve that. Later variants like Kel34 and Mike's wire the first pentode as triode and offset the lower gain (restore the sensitivity) with reduced fb.

Component wise you could try small film caps across the electrolytics to give a path for rf to ground. Also better diodes such as hexfreds or schottkies which produce less noise. Increase the smoothing too, perhaps with a choke, if it is using just the original 68uF at the mo.

None of this is right or wrong as it only has to play music and please the owner. It just happens that, once we get over the initial wonder that the thing works at all, we sometimes recognise shortcomings that we can live with or need to work on

Rich

[Dave Ed]

It just happens that, once we get over the initial wonder that the thing works at all,

I like it! My sentiments exactly-only because I'm a relative novice to this game-I definately belong in the 'Poor Clueless Pilgrim' category at the moment.
As a bit of background I,ve already built the Kel84 earlier this year and because it was such a resounding success it spurred me on to delve a bit deeper.
I don't have any test equipment just ears and a multimeter so I'll happily take on board all comments-at some point I'm going to start changing components -the fun is in the journey!

[Mike H]

Crikey, lots of things here:

Originally Posted by Richard

Yes, the Maplin metalfilms used to say Philips in the catalogue I think. ... Perhaps best not to stuff the whole amp with them ... as they can get tinkly bright but not gritty. Of course they might reveal rough valves (but not GEC KT66's).

Sorry to raise a bit of a stir chaps, I think I meant 'bright and tinkly'. Depends how you define 'gritty'. Certainly can make it 'sharp', again will also depend what else is in there! Yes I used the Maplin 2W MF in a Williamson clone w/KT66's (fr the GEC version having UL o/p, not triode), seemed okay at the time ('cept I'm wiser now ~ or more fussy?... )

... Chelmer aren't a maker so they could be from various manufacturers. <snip>

I could be wrong but I'm under the impression that their basic 'premium' type ('CVC' marking) might be e.g. Chinese new ones and that kind of thing. Not terribly special imho, but will 'get you up and running' at min. cost. But they also do better equivalents or even genuine NOS if they've got it, depends how much you want to spend! Personally I prefer to try for the NOS etc.

Originally Posted by Victor

I`m really impressed this post is still getting hits and replies.

Ditto!

If anyone is stuck for the diagrams or anything I can make a small website when I have time with the articles etc. I still have the magazines in perfect condition.

Yes do! And make sure it can be googled as well

I see it as the poor mans introduction to valve sound!

Yes indeed I believe HFW printed something to that effect too

People forget that the Maplin engineers worked on this amp for a short time and not as much as other Valve companies that well...Sell high end kit!!

Mostly that was me, most everyone else 'stood around and criticized' ~ no that's not entirely accurate, they had other projects to be getting on with as well ~ tho was amazing how many people kept appearing with 'helpful suggestions'

Personally mine sounds fine,but now listening to the modifications people are doing it might be beneficial to improve on the design!!

Well I think so ~ not terribly difficult

Has anyone built or heard if the velleman kit valve amp is any good?

Only really familiar at all with the K1040 (?), stereo 100W UL, 8 x EL34's, Maplin lab had one going off the radio all day every day. Used to blow EL34's at regular intervals, I was once told, plus it was damn hot. All the shine seemed to go off it after a while (had a mirror back panel). Plus the basic gain wasn't enough hence there was an extra triode stage added to the front end. Bit untidy cct to be honest

Originally Posted by Dave Ed

nice mid but treble can be a bit 'gritty' ... Interesting that others don,t find this with their amps, mine is still 'under development'-Mike has suggested it could be an RF problem?

Woah hold on, I'm not saying that's definitely happening, just something to be bourne in mind as a possibility, and what steps to prevent it. Did have a bit of bother with it on my Williamson clones ~ put the 'scope on the speaker terminals with the loudspeaker leads connected I started seeing AM radio signals

Originally Posted by Victor

To add to the topic. There was also a pre amp made for this amplifier published before this millenium amp. I have not seen anyone who has made the matching pre amp to date.

No was definitely published afterwards...

Originally Posted by Ianm2

I have seen the pre schematic. Its a cathode follower active line stage. ecc82

That was the best bit about it, that worked super

bass and treble active tone controls ecf80

Had endless problems with that...

interesting, I have only recently found out... ef...pentode; ec triode; ecc double triode; ecf pentode, triode efc 80 is a combo I think of ef 86 and ecc83

Umm sorry no it isn't, see below...

I've hade to divide this into two separate posts otherwise too long!...

[Mike H]

el power pentode; ecl pentode, triode, ecl 82 is a combo of el84 and ecc83, wow.... fascinating eh?

More accuately: E = 6.3V heater; G = 5V heater; B = double diode (usually[?]); C = triode; F = small signal pentode; L = power pentode; Z = rectifier; 3 = Octal; 8 = Noval (B9A socket)

E.g. EBC33 = 6.3V heater, double-diode triode, Octal, last number = version?

GZ34 = 5V heater, rectifier, Octal, ?...

ECC83 = 6.3V heater, double triode, Noval, and ?... whatever development version it's up to I presume.

The US numbering system is of course a whole different can of worms...

Okay ECF80, and it's ilk ~ essentially this is a radio valve, specifically, for use in VHF tuner heads and suchlike, where the pentode is the 1st IF stage and the triode is the local oscillator. The LO is a tuned grid type with positive feedback from cathode to grid, with the tuned cct on the grid. The thing is it (the triode) is specialised to this task, which makes it pretty much useless for anything else, 'specially audio; the voltage gain is usually terrible for example. Amazingly tho it's often seen as the concertina phase splitter in e.g. a EL84 PP amp. The ECF80's one isn't too bad tho, whereas the ECF82's is a dead loss really. That was one of the problems I was having, didn't know about all ins and outs at the time tho. Also just an inch of two of wire on the grid and it's making funny patterns on your TV ~ if it's turned on ~ the thing's transmitting UHF all over the place!

Biggest problem with the 'Newton' tone control (ECF82) it ran so hot the crimped terminals on the pots would come loose ...?

and the mpalin pre's phonostage is v similar to the rca/gec one, using ecc83s, passive riaa and very stadard resistor values,

Yes that was okay, actually based on Richard Brice's cct as was published by Wireless World 1984(?), 'course had to throw away the 'superfluous extra valve stages' due to cost cutting, I would do it a bit differently now

good attention as with th epower amp to the power supply....

Yes wow actually managed to get a smoothing choke included in it, wonders will never cease

hats off to mike

Well thanks for that anyway!

again, I like the classic brit valves ... sadly mullard are the best and dearest.

Same here really, if you can get 'em

best new is svet winged c, totally agree with rich.

Yes currently using Svet 300B's, very nice. Also got cheaper Chinese ones and Chelmer CVC, not so much, bit 'screechy'

Strewth there's more...

Originally Posted by Richard

Could be lots of things, maybe showing up shortcomings elsewhere in the system or simply that the new presentation is unfamiliar.

Had plenty of that!

Many folk love/hate EL34s for exactly this reason. Of all op valves they are perhaps the most colourful though they can be neutral with some work

Yes heard that too ~ so yes use 'em if you like that kind of sound else something else ~ obvious really innit?

Can you scope it on square wave first to check it's not something fundamental? This circuit usually rings a bit but the amount depends on the quality of the op tx.

No he's not got a 'scope (I presume you mean Dave); should be about a 20% overshoot I'm guessing, with very short ringing

Also try lowering the amount of feedback which tends to make for a more open and involving sound and will improve stability. The circuit was something of a showcase for low distortion for Mullard at the time and has quite a lot of fb to achieve that.

Yes I agree with as minimal feedback as you can get away with, that's one of the reasons why I thought it was a good idea to change the ECC83 to an 82. As it is the Mullard cct's open loop gain for V1 and V2 alone is in the thousands (can't remember the exact number, did work it out), which is rediculous, 1,000 is more than enough if not still too much. Problem is input sensitivity is about 220mV as it stands, which Dave thinks is too much already; lowering the NFB any more will result in a rediculous amount of sensitivity!

[Mike H]

Nearly forgot to mention, Mullard's 520 is directly based on their forerunner 510 cct (EL84's); the 520 coincides with the release of their then brand new EL34 type in 1954. In other words it was a marketing excercise to sell the valves.