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by Paul Barker
Sun Mar 24, 2024 8:50 am
Forum: Everyones Projects
Topic: Directly Heated 1619 SET
Replies: 18
Views: 522

Re: Directly Heated 1619 SET

Well I get the point, and I liked the mofo at Steve’s in Hull. But I prefered the 45 and its worth the cost. Right, after looking at the 6SL7 it is woefully short of 2nd distortion. It has enough gain for a single stage though. But searching for luscious sound it came to mind carry on with the e88cc...
by Paul Barker
Sun Mar 24, 2024 7:53 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 149
Views: 32321

Re: OK…so I’m on wi’ summat

Circuits: 1. Audio Circuit with measured voltages: EL34Audiocct.png 2. Choke input power supply: EL34LCinputPSU.png Sorry to be a pain in you’re proverbial Stephen but I looked at youre blokes circuit to see if I could use his design of the use of the 6sl7. Having tied myself in knots following a t...
by Paul Barker
Sat Mar 23, 2024 8:47 pm
Forum: Everyones Projects
Topic: Directly Heated 1619 SET
Replies: 18
Views: 522

Re: Directly Heated 1619 SET

I vaguely recall the E88CC calculated out with 8% so that may help. I’m prepaired to find its not as good as the EL34, plus that’s more powerful. Its all a surprise how it turns out sounding. The 6550 was more powerful but unemotional. EL34 is less powerful but tone full. Reports about the beam valv...
by Paul Barker
Sat Mar 23, 2024 5:55 pm
Forum: Everyones Projects
Topic: Directly Heated 1619 SET
Replies: 18
Views: 522

Directly Heated 1619 SET

Using the 6V6 triode curves 18Watts total dissipation, I see the strange 2nd harmonic reduction found in A2 operation because the left most curves pich together similarly to the right mose curves. So into 4k7 we see 5 Watts SET at 5% 2nd. Condisering the EL84 only achieves 2 watts power out, that is...
by Paul Barker
Fri Mar 22, 2024 1:00 pm
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

Meanwhile b+ delay fully automated.

Image
by Paul Barker
Fri Mar 22, 2024 11:18 am
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

Eric has cap coupled to the A2 output stage which is supposed to cause “blocking distortion” in A2 Yep, it is a bit ugly that output stage. No need for quotes around blocking distortion, its a real thing and it will happen in that amp. he has tried to avoid it by using as big a coupling cap as prac...
by Paul Barker
Fri Mar 22, 2024 7:36 am
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

After which I may never need to build the GM70. So, lets just look at the PX25 and then look at any other ideas, to make sure we aren’t in error. From the Vade Mecum there are two SE operating point options.h Vade mecum option 1/ 400v -31 62.5mA into 3k2 (but I’d be into 4k7) gets 6 watts @ 6% 2nd h...
by Paul Barker
Fri Mar 22, 2024 7:30 am
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

https://i.postimg.cc/W4JSBp0c/IMG-1157.jpg So Ive been thinking of “this EL34 migration circuit requires a challenge” Can it really be this good. But actually progress would come from starting the GM 70 build. Just a quick diversion there and more detail about Eric Barbour’s concept circuit. Eric h...
by Paul Barker
Fri Mar 22, 2024 6:22 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 149
Views: 32321

Re: OK…so I’m on wi’ summat

There were a lot of good SE circuits with the oil cap philosophy. This one below for example. This circuit also was the first to introduce the 6EM7. Eric Barbour was the US rep for Svetlana for a while, but disappeared off teh scene early doors, and the Svetlana website vanished too. https://i.posti...
by Paul Barker
Sun Mar 17, 2024 9:01 am
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

https://i.postimg.cc/JztSR81n/IMG-1154.jpg At the moment single ended one valve has a 4k6 load, but I drew the above to see what PSE looks like but the opt’s are 2k ohm. This graph represents 4k because two EL34’s achieve double the power. So power out becomes 16 watts. Don’t ask me where the disto...
by Paul Barker
Sun Mar 17, 2024 7:07 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 149
Views: 32321

Re: OK…so I’m on wi’ summat

Agree.
by Paul Barker
Fri Mar 15, 2024 9:04 pm
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

I found the electro harmonix EL34’s sound much better. But thats a bonus because a single New Boxed GE 6550 /KT88 £195 on Ebay. So Ive got 8 and 6 used but work like new 4 sovtec and two Tungsol made in Britain. 🇬🇧 so I can sell those, since EL34 much better sounding.
by Paul Barker
Fri Mar 15, 2024 6:41 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 149
Views: 32321

Re: OK…so I’m on wi’ summat

Oh pooh, really sorry to have to tell you this, honest I wasn’t copying you. I adjusted b+ in my amp to get g2A 425v the bias on the cathode 39v 48 mA. 21 watts dissipation. Totally better by a mile than the 6550.Diana just nuck up on me, I nearly jumped out my skin. “Gosh its sounds really……signifi...
by Paul Barker
Fri Mar 15, 2024 5:26 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 149
Views: 32321

Re: OK…so I’m on wi’ summat

Envious
by Paul Barker
Fri Mar 15, 2024 5:18 pm
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9440

Re: 6550 SE Amplifier

The good news is non of the output valves are sounding any different but a couple GE’s are 5v down in bias. The 4 Sovtec’ all ST62 are 5v down including the fourth which was never used. The GE’s sound better and drawer more current. But the Sovtec’s are all the same as the new one of the four. So no...