45 SE

What people are working on at the moment
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Cressy Snr
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#61 Re: 45 SE

Post by Cressy Snr »

Spent an enjoyable afternoon playing with scenarios, this time with clip leads, so things could be changed rapidly and quickly assessed for yes or no. Here's what happened:
First up was the 220uF black gate cap plumbed into the power supply as suggested by Nick.
Even though the cap hadn't been used for a while, you'd have had to have been deaf not to hear the improvement in the already great treble quality.
I had with the BG cap, not even run in, the best top end I've ever heard from my any of amps...ever! And that's not hype either, it really was that good.
The levels of fine detail were subtly improved as Paul had suggested they would be. It wasn't night and day, but nevertheless it was there.

I spent a very enjoyable hour and a half with the clip leaded lash-up, listening to the whole presentation slowly improve, so that the gains in the treble quality I'd heard from the start, began to be replicated across the whole frequency range, and the overall levels of finer detail subtly increased again. This was getting good.

It was then that looking at the circuit wiring, I had a brainstorm. So powering the amp down, I did this to the power supply:
45splitPSUsortof.png
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After powering back up, I put on the same CD of Kenny Burrell's "Midnight Blue" I'd had on earlier.
'Chitlins Con Carne' was bloody awesome with fine cymbal work and loads of 'yeah's and 'hit it man's going off in the background. This group interaction is something I've not heard at all on this CD before, and I had it for thirty years. Kenny's guitar was palpably present and Stanley Turrentine's sax had a texture I'd not heard from it before...bloody hell!

'Mule', is quite a subdued track, but the levels of intimacy going on between Kenny's guitar and Major Holley's bass sounded astonishing to someone like me who has not heard 45s before. I had turned away from the speakers, towards the window, when Bill English closed his hi-hat without hitting it. It frightened the life out of me and I shot round to find that there was a miniature drummer live in the front room. OK so the dynamics of a real drum kit weren't there but my God It was lovely.

And as for Ry Cooder' with 'Mary Elena' from 'Boomer's Story' :love4:

I won't babble on any longer, but to be honest, I'm humbled. I thought I'd heard some and knew at least a little bit about how a music system ought to sound, but fecking hell, the scales have fallen from my eyes this afternoon.

Alright settle down! Yes I've committed the cardinal sin of changing something, then not evaluating the result at the proper length, before doing something else, but at least, in the first instance I changed just the one thing.
And I've gone all hysterical again, unable to keep to the script and unable to keep my emotions away from cold hard science, but what the hell, this is just wonderful. I'm in love with my music once more. It's been a long time coming.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
Cressy Snr
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#62 Re: 45 SE

Post by Cressy Snr »

Inside now it's all soldered up:
IMG_0666.jpeg
IMG_0666.jpeg (126.1 KiB) Viewed 3901 times
And working in the system, with the WKZ having replaced the JJ at the front:
IMG_0668.jpeg
IMG_0668.jpeg (101.1 KiB) Viewed 3901 times
I'm in love with 45 triodes. I can't see myself using anything else from now on.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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IslandPink
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#63 Re: 45 SE

Post by IslandPink »

Cressy Snr wrote: Fri May 07, 2021 8:17 pm And as for Ry Cooder' with 'Mary Elena' from 'Boomer's Story' :love4:
Oh, thanks for reminding me about that one. One of the most beautiful things I've heard, too. I'll fire up the 45's, Black Gates and ribbons later for a quick reminder !
"Once you find out ... the Circumstances ; then you can go out"
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Nick
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#64 Re: 45 SE

Post by Nick »

Would it be a real SQ improvement using a Monolith Magnetic S-9/SA-9 ($350/$500 ) instead of an Electra print TM3KB ($145) for example
You are right of course about the output transformer, but I was taking it as static in the conversation with Steve. I don''t know any of those transformers so I cant say. Personally I like Amorphous core transformers from AE Europe, but lots of things can be more important than the core IMHO, in particular the inter layer insulating material.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Cressy Snr
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#65 Re: 45 SE

Post by Cressy Snr »

OK, so after that euphoric rush of flowery prose, for which I don’t intend to apologise, I just need to re-check all the voltages and currents, to make doubly sure the 45s and the WKZ aren’t being thrashed, and transfer them to the schematic, then I think we have a wrap until I can get the amp to a meet sometime.

For what it’s worth (and aural memory can be a fickle thing, particularly after 10 years) but even without the 6080 series regulation I think this circuit beats my 6B4G monoblocks: an excellent result!

Also, I think this little amp shows that there is still plenty of mileage left in the concept of an ultra-low power SET feeding 100dB plus, single driver speakers. These tubes have shown me just how good single, full-range drivers can sound when fed with the right signal. The big Fane 12-250-TC are astonishing value for money as are their more expensive, even bigger 15in brothers. Maybe driver size is an advantage. It seems so.

Just remains to thank everyone who has provided parts, tubes and advice for this rather short project: one that is giving such great listening pleasure. You know who you are. :thumbright:
Sgt. Baker started talkin’ with a Bullhorn in his hand.
Cressy Snr
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#66 Re: 45 SE

Post by Cressy Snr »

The amp has been checked over and voltages/currents measured and recorded on the schematics below:
45Audiocct.png
45Audiocct.png (74.18 KiB) Viewed 3786 times

I've brought the HT down a little, using 33R of resistance in each leg feeding the rectifier. The resulting 316V keeps the 45s happy at 261V and 32mA, which gives a plate dissipation of 8.35W, so we are looking at around 1.5W of power output. The chosen HT also keeps the Black Gate WKZ cap, well within its 350V rating: no chance of it going over:
45PSU.png
45PSU.png (94.62 KiB) Viewed 3786 times
Anyway, there we are.
Last edited by Cressy Snr on Sat May 08, 2021 5:27 pm, edited 1 time in total.
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Cressy Snr
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#67 Re: 45 SE

Post by Cressy Snr »

There are a number of possible improvements that could be made: the obvious one being better output transformers. But there are a couple of others, such as a good stepped attenuator at the front and possibly an easy one involving making the EF80 into a pentode driver, as suggested by Nick earlier in the thread.

These are long term aims however because the basic amp as it is now, suits me very nicely and will be enjoyed through the summer months. I’ll think about the above changes around Sept/Oct.

Until then….TTFN. :)
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Cressy Snr
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#68 Re: 45 SE

Post by Cressy Snr »

I feel obliged to make one more post.

We spent all day yesterday and into the evening, listening to music and Melanie (and me for that matter) were loving what this amp does with classical, both of the chamber variety and the bigger works, including operatic stuff from Anna Netrebko, Domingo and Pavarotti. She wouldn't turn the bloody thing off! As I'm writing this, she's reading whilst listening to a cycle of Handel violin sonatas, with William Christie (violin) and Hiro Kurosaki (harpsichord) on Erato.Excellent stuff!

I started blathering about pentode drivers, different output transformers and steeped attenuators and was met with, "Don't you dare touch that amp! I've not been able to appreciate music as good 'til you built that! If you want to mess about, put them other two 45s on a bit o' wood or summat! That one's staying as it is!"...Well that's me told then.

Mind you, I can't really complain about the EF80 triode strapped driver. I've put my exact operating conditions onto Tom Schlangen's 2005 curves and it certainly looks pretty good:
EF80astriode_in45se_SC.png
EF80astriode_in45se_SC.png (125.81 KiB) Viewed 3691 times
So... any further tomfoolery with this particular project looks to be out of the question, especially if I want to stay alive. :lol:
She's never really shown much interest in the sound/music making ability of anything I've done previously, so I'm quite chuffed to be honest.
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Wolfgang
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#69 Re: 45 SE

Post by Wolfgang »

I still couldn't figure out how you made adjustments for the load impedance for all the different tube types which you have used together with the same OPTs and speaker impedance. Did you calculate the details, measure the results? Or did everything simply fall into some kind of "grey zone" where everything worked somehow, some with more THD, some with less etc, and it was all ok (just by listening to the results)? How precisely has the speaker impedance to match with a specific load impedance/OPT windings ratio? In my case for example I would have to use 15 R Lowthers with a 13,5R calculated impedance. Is this close enough? What are your numbers with the 45?
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Nick
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#70 Re: 45 SE

Post by Nick »

Is this close enough
Its all a bit of a guess, for a start its assumed that the load is resistive so a fixed impedance with frequency. and that’s so far from the truth that it is a joke. Secondly we ignore the reactive component of the output transformer, so just drawing the load as a line is wrong as well.
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Cressy Snr
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#71 Re: 45 SE

Post by Cressy Snr »

Wolfgang wrote: Mon May 10, 2021 4:17 pm I still couldn't figure out how you made adjustments for the load impedance for all the different tube types which you have used together with the same OPTs and speaker impedance. Did you calculate the details, measure the results? Or did everything simply fall into some kind of "grey zone" where everything worked somehow, some with more THD, some with less etc, and it was all ok (just by listening to the results)? How precisely has the speaker impedance to match with a specific load impedance/OPT windings ratio? In my case for example I would have to use 15 R Lowthers with a 13,5R calculated impedance. Is this close enough? What are your numbers with the 45?
I didn’t calculate, I have no means of measuring. In fact, the Hammond 1627SE output transformers I have are the only pair of single ended OPTs I own and due to their 2K5 primaries, they are theoretically worse than useless for anything but 2A3. I am on a tight budget, so changing to a more suitable, higher primary impedance OPT is difficult and not really an option.
With all this in mind, I have had to fudge the existing transformer by configuring the secondary for 4R and connecting my 8R speaker, to give a reflected impedance of 5K, which is suitable for EL34, KT77, 807 and 45. There are all sorts of issues with this band aid method, compromised coupling, inductance and stuff I probably haven’t even thought of.

However it could have been a lot worse had I not owned the earlier 1627SE with its multiple secondaries and instead had the 1627SEA, which has a single tapped secondary.
This is my transformer
9082AF68-D27C-4CF0-9F6B-FAA294C6947C.gif
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So parallelling up the 2x4R windings then putting an 8R speaker on the end, sidesteps the coupling issue to a degree as I’m using most of the secondary, but it would have been better to have had the right transformer, there’s no getting away from it.

So you can see that any claims I might make about how fab the sound is and how intimately close to the music it gets my wife and me, could easily be dismissed by the better educated as the rantings of a deluded fool and as such, ought to be treated with skepticism, even contempt. But….it all works. And worse, I don’t know why it works as well as it does, I wish I did. Synergy can be such a cop out, more often than not the preserve of charlatans and flim-flam merchants, but there's not a lot else I can say, except the way this amp connects us with the music, is like nothing else we’ve experienced in the forty years we've been listening to so called hi-fi systems. That's just the way it is.
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Paul Barker
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#72 Re: 45 SE

Post by Paul Barker »

Thanks for the update Steve. Warms the cockles of my heart.
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#73 Re: 45 SE

Post by Wolfgang »

Thanks for the answers. I guess I simply will take my chances and start somewhere .
Cressy Snr
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#74 Re: 45 SE

Post by Cressy Snr »

Paul Barker wrote: Mon May 10, 2021 8:01 pm Thanks for the update Steve. Warms the cockles of my heart.
Cheers Paul,
My eyes have certainly been opened.
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#75 Re: 45 SE

Post by IslandPink »

Nice to see it working out so well.
"Once you find out ... the Circumstances ; then you can go out"
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