And another amp or two

What people are working on at the moment
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steve s
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#1 And another amp or two

Post by steve s »

I've was building a simple solid state amp just after Christmas but I struggled to get it quiet, so I packed it away when I started on the px4 amp for the wam show. I ordered some boards / kits from China which came a few weeks ago. I've built them up but they sounded dire next to the valve amps... I tweeked them by replacing the input cap and bypassing the output cap then fitting some 90s tfk chips.
With a good CD they now sound really quite good. Good recordings where replayed with a lovely sweetness and delicacy not quite at the px4 standard but not far off. The trouble was with slightly lesser recordings the sweetness and realism faded where the px4 amp just seem to dig deeper into the recording.
I've just got some twin rail power supply boards which may improve things as they remove the output cap.
So as they say, one job leads to another.
Anyway this weekend I decided that I would convert the pp3531 board to take the old (90 years) p650s I have.

I tested them and a batch of 85 year old mh4s so started yesterday with the conversion.
Finished the job today and it's been running all afternoon.
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I've swapped the transformers out for tribute amorphous 5 k, which seems to agree with the valve. Adjusted the voltage and surprisingly everything settled to where my calculator said it would.
Sound wise it is good and a very clean sounding 1.1 watts, which don't sound much but it plays very loud and fills the room at 1/2 volume.
What it does is fantastic reproduction
I can't believe the subtleties and realism. I thought the px4 was good which in turn I thought was better than the px25.
Cymbals and the like seem faster and more dynamic. I'd like to say the differences are subtle but not to me when I'm used to what I'm hearing. Far from subtle
It the best sound I've had so far.

The mh4 and the p650

20200331_162639_copy_768x1024.jpg
And next to the px4 for comparison
You can see the extra hight of the anode compared to the px4, they are beautiful ( yes I'm a saddo)
20200331_162639_copy_768x1024.jpg
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The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
Cressy Snr
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#2 Re: And another amp or two

Post by Cressy Snr »

Great stuff Steve.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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IslandPink
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#3 Re: And another amp or two

Post by IslandPink »

Very cool things !
"Once you find out ... the Circumstances ; then you can go out"
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Dave the bass
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#4 Re: And another amp or two

Post by Dave the bass »

Phwwwwwwwwwwwwoooooooooooaaaaaaarrrrrrrrrrrrrrrr!
"The fat bourgeois and his doppelganger"
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Ali Tait
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#5 Re: And another amp or two

Post by Ali Tait »

Nice!
steve s
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#6 Re: And another amp or two

Post by steve s »

Cheers gents.. the amps had a good session tonight, I'm very pleased with it, one of those sessions when the tracks you know well and theres little background details that you don't remember hearing before suddenly appear. I didn't expect that from it. The leading edges are sharper and theres more texture,
I'm really pleased
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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Ray P
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#7 Re: And another amp or two

Post by Ray P »

Keeping you off the streets Steve!

Those old valves do look lovely don't they.
Sorry, I couldn't resist!
Max N
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#8 Re: And another amp or two

Post by Max N »

Someone should make a film, ‘Tube Story’ (like Toy Story, see) where the heroes are valves that wait 90 years for someone to build an amp for them, so they can finally make music.....
Sorry I’m welling up at the thought of it.....

Hope to hear them one day Steve :D
steve s
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#9 Re: And another amp or two

Post by steve s »

I revived an old chassis and managed to fit most things in it after quite a bit of cutting
I could not fit the giant Jensen coupling caps in but fitted a quality volume control.
It sort of didn't sound as good as remember it doing, but it's still very good.and looks half decent
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The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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Nick
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#10 Re: And another amp or two

Post by Nick »

It sort of didn't sound as good as remember it doing
Thats the problem with boxes :-(
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
steve s
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#11 Re: And another amp or two

Post by steve s »

The makings of another amp.. not sure what to put in it though..
But making the most of this nice weather to do the woodwork
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The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
Cressy Snr
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#12 Re: And another amp or two

Post by Cressy Snr »

steve s wrote: Sat May 09, 2020 1:30 pm The makings of another amp.. not sure what to put in it though..
But making the most of this nice weather to do the woodwork.
Shoddy as ever Steve. :)
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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