PSE EL84 Amplifier

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Paul Barker
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#16 Re: PSE EL84 Amplifier

Post by Paul Barker »

Mike H wrote: Fri Apr 05, 2024 8:07 pm Just IMO, I don't like the idea of 2 x EL84 in parallel, seems like a step too complicated. Also getting them biased the same with fixed bias couild be a headache. So then what, separate bias circuits with trimmers?

I assume the issue is must drive a 2.5k primary?

Why can't the secondary load be altered to make it 5k primary? Just wondering aloud. :D

As said just random musings :D
only one tap, 8ohm. As you know ratio is only thing calling it the impedance it is. Inductance is way higher than required for that supposed (in name only) impedance. But today if I wanted better bass I would follow Simon. There is no longer any point to building a valve bass amp. Last century the place my head was. Valves could do no wrong. But my single amps do kick out enough bass for my requirements. Quad 57’s are wide band enough for me and el34’s at 6 watts satisfy me mated with them. The Quads are better than any speaker system I developed inspight of all the money I wasted chasing that crop of gold. Maybe If Id paid Bruce Edgar to box a set of his horns in a crate and ship them to me, I would have had a big smile. I left it too late, like everyone Ive treasured and lost, suddenly he passed away.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#17 Re: PSE EL84 Amplifier

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Paul Barker wrote: Sat Apr 06, 2024 10:10 am
Mike H wrote: Fri Apr 05, 2024 8:07 pm Just IMO, I don't like the idea of 2 x EL84 in parallel, seems like a step too complicated. Also getting them biased the same with fixed bias couild be a headache. So then what, separate bias circuits with trimmers?

I assume the issue is must drive a 2.5k primary?

Why can't the secondary load be altered to make it 5k primary? Just wondering aloud. :D

As said just random musings :D
only one tap, 8ohm. As you know ratio is only thing calling it the impedance it is. Inductance is way higher than required for that supposed (in name only) impedance. But today if I wanted better bass I would follow Simon. There is no longer any point to building a valve bass amp. Last century the place my head was. Valves could do no wrong. But my single amps do kick out enough bass for my requirements. Quad 57’s are wide band enough for me and el34’s at 6 watts satisfy me mated with them. The Quads are better than any speaker system I developed inspight of all the money I wasted chasing that crop of gold. Maybe If Id paid Bruce Edgar to box a set of his horns in a crate and ship them to me, I would have had a big smile. I left it too late, like everyone Ive treasured and lost, suddenly he passed away.
My half day sat with him my mouth dripping at his every word are a life long memory to treasure. Backed up by his superior sound far out infront of all other sounds at VSAC 2003. We didnt know at the time. But more went on there than we know about. Firearms involved. Thats when you go to a nation where people have a right to carry. We ought not forsake our peaceful gatherings. My self though, I think its clear as day, I would prefer more valve involvement. But I still come if I have a valve project ready. Sadly my last effirt wasnt ready.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Nick
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#18 Re: PSE EL84 Amplifier

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You should try and get away for the day and come over to the North West Audio Show (22nd/23rd June, Chester area). There normally are some systems that are a cut above what you might expect from commercial kit. Not trying to convert you or sell to you, but it just would be interesting to maybe re-calibrate.
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Paul Barker
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#19 Re: PSE EL84 Amplifier

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Good idea. I have no vehicle on the rd a scrap van outside the house and a car born 2005 sorn at covid as covid crippled me financially the lovely conservatives didnt support people who hadnt been self employed for a year infront of the covid outbreak. As I dont have a crystal ball I wasnt able to know covid would apear in a year’s time.

I dont like the politically conservative. So the car was sorn and the van had to make do. But it wont make do any longer. Its too far gone.

So a car with ceased breaks from standing and probably a lot of other things rotted in its time ignored, is my best hope.

After covid and continuous conservative rule, the Ukrain conflict the Israel conflict and very bad conservatives given a turn in charge, it was the motor trade’s turn to form a cartel with government permission and rob us blind for any vehicle I cant afford. Not forgetting fuel prices and interest rates (mainly due to the flagrant way Lis Truss sold herself to the super rich puppet masters, causing a confidence crisis for far too long before she back tracked, much too late imho.

So car might get road legal before then.

Lease costs are about 4 times what they were in 2004 when Imleased a new van every two years from Citroen. Now, leasing is exhaubitant and way above the worth, people on minumum wage standing like a pansy at the door of Tesco will earn far more than a self employed gas man. At the moment Im doing a few jobs if the customer comes for me and takes me home. Or Ive cycled used my bus pass and walked to very few jobs.

But because I have to keep an eye on Diana and do all the houswork, which Im a long way behind in. Its a good job I get the state pension ,imus £100. Diana gets full state pension. But council tax is £2,400 a year, gas and electric is 500 a month, but I should change supplier because they must have at least £2,000 of my meagre resources. Lockup has to go. But not until I have a vehicle and months to dump stuff put right damage done to lockup when my own made mezanine floor collapsed. My still valuable items in there like some valves a torroidal winding machine a laithe and other machinery, boiler spares etc. most can be dumped though. Until though, that costs me £190 a month.

You cant live on state pension in todays costs.

But on the bright side the people who decide have told Diana she shall get PIP. We just dont know what PIP and when. But there is a horison light coming on soon we hope. If she diesnt die first, but anyway when she dies no more PiP. Then I’ll probably give up audio sell the house buy a big van and wild camp.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#20 Re: PSE EL84 Amplifier

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It may be already too late, but before going wild camping I’ll be found trying to sell my valuanle audio stuff at whatever the National Vintage Radio Fair has become by then.
I’ll have to give it all up when Im wild camping.
Or I may be found on a canal in a 72ft converted barge, or a boat in the harbour and a van on land when the storm comes.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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#21 Re: PSE EL84 Amplifier

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On the bright side Ive found out where you get youre 500x500 sheet of stainless guillotined in Scarborough. I’ll go there on the bus when theyre next open; Monday.

But a word to the wise, just buy another Hammond Chassis next time, it will be cheaper in the long run, and as you should be downsizing anyway sling the broken audio purchases away. I could never have fixed the Rosenblit otl it wasnt made to diy repair. But it didnt sound good enough anyway.

But I have some silver god caps a pair of desirable Russian valves selling for 50 each on ebay or 100 new and some other russian valves selling for 20 each. A filament transformer I cant use in this project and a stepped attenuator I’m suspicious of because its made of cheap metal film resistors.
Last edited by Paul Barker on Sat Apr 06, 2024 12:31 pm, edited 1 time in total.
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#22 Re: PSE EL84 Amplifier

Post by simon »

Paul Barker wrote: Sat Apr 06, 2024 10:10 am But today if I wanted better bass I would follow Simon. There is no longer any point to building a valve bass amp. Last century the place my head was. Valves could do no wrong. But my single amps do kick out enough bass for my requirements. Quad 57’s are wide band enough for me and el34’s at 6 watts satisfy me mated with them.
FWIW at 6W I still think GM70 SET is a good option. The bass was great, really tuneful, and that was with the coppers which are reckoned by some not to be as funky in the bass as the cooking graphites.

What did surprise me when switching to 45SET was more detail in the mid and treble compared to the coppers. I haven't switched back, but enjoy the positives of chips lower down and valves where it counts for me. But GM70 bass might be nice - I haven't tried it instead of the MoFo but I've thought about it...

As an overall package the low HT GM70 amp is hard to beat. Apart from energy consumption, iron, real estate etc.
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#23 Re: PSE EL84 Amplifier

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Great to hear, I can do 6 watt with a 630 volt power supply. But I dont really think its worth building at all for just that. So I’ll wait until Ive built it for proper voltages. As I have a 6 watt amp.
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Nick
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#24 Re: PSE EL84 Amplifier

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What did surprise me when switching to 45SET was more detail in the mid and treble compared to the coppers.
May not be the case, but what I have found you can't ignore is how much simpler it is to make a good transformer for a 45 than it is a gm70. And one of the things I find a good rather than an average transformer gives you is "more detail in the mid and treble". Paul used to turn up at mine (15-20 or so years ago I guess) with an amp on a breadboard with some obscure (to me at the time) triode 1W SET and it was a source of constant depression how much better it was than anything I had (WAD 6550 at the time). With hindsight I released the magic was 1. better output transformers, and 2. No bass worth speaking off. The 2, was the killer, the lack of bass meant that it was so easy to be blown away by the mids and treble.
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#25 Re: PSE EL84 Amplifier

Post by simon »

No they're good points. I was thinking earlier how different the amps are - whilst they're both SETs they're quite different really.

I don't remember the bass being compromised switching to the 45s, but I was using class D with the GM70s too as I'd found the passive crossover robbed life and detail.

Aural memory over a long time is a bit flaky, but when I first built a Bugle 15+ years ago I used 5k AE amorphous c cores with the 208eZ horns and the bass thundered - the best bass I'd had at that point, better than 2A3 and 300B. It really surprised me.
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#26 Re: PSE EL84 Amplifier

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Ive just walked to Eastfield with my new top plate. R & R engineering kindly guillotined it for me.

Fukc diving into the GM70 project. Ive change tack again, consudering Mikes fears and considering my past experience. Im makling the four Mullard EL822’s as push pull output on a ccs tail with a balance pot and 1 ohm sense resistors. Ive also ordered two brand new dark black glass Mullard EL821’s as driver tubes, Sukuma style.

This power supply ive shown will work the same.

John Caswells Sowter PP opt’s will do the job.
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#27 Re: PSE EL84 Amplifier

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A bit of 2nd dominance at the driver and a bit of distortion cancellation at the output.

Should blend good.

Mullards for less than Chinese or Russian.

Imageimg post

Should look better.

Image

Image

I owe the factory in Eastfield Tea money.

Glad to find the-milk of Human Kindness is functioning well.
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#28 Re: PSE EL84 Amplifier

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Diana was wrong they havent awarded her pip her disability isnt enough.

She’s only barking mad and demented.

My mate has been offered 40k basis for the manager of his old firm that was liquidated. But I cant apply because Id find Diana dead when I got home one day, and probably the house burned down. Only two days ago she had the microwave on with nothing in.
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#29 Re: PSE EL84 Amplifier

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Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#30 Re: PSE EL84 Amplifier

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Anyway making amps that I want to make keeps me happy and Roxy my best friend. Trimming my nails. Image
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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