EL84 equivalent

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geoff 1965
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Re: EL84 equivalent

Postby geoff 1965 » Sat 04/27/19 7:39 pm

the single input jack goes into both triodes of the preamp tube "parallel" and the concentric volume pot lets you control both triode signals seperately i.e. you can use one triode or blend them together,it's the same as using a jumper between the inputs on the old plexi marshall's blending the normal channel with the bright channel.
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Re: EL84 equivalent

Postby crgfrench » Sat 04/27/19 9:11 pm

geoff 1965 wrote:
Sat 04/27/19 6:51 pm
the more i look into these ecl86's the more i am impressed,have a listen to this amp!
https://youtu.be/GsWzUMqA5W0
talk about coincidences, that guy, Mark of Frugal Amps, lives right near where I grew up!
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Re: EL84 equivalent

Postby crgfrench » Sat 04/27/19 9:16 pm

geoff 1965 wrote:
Sat 04/27/19 7:39 pm
the single input jack goes into both triodes of the preamp tube "parallel" and the concentric volume pot lets you control both triode signals seperately i.e. you can use one triode or blend them together,it's the same as using a jumper between the inputs on the old plexi marshall's blending the normal channel with the bright channel.
1959u.gif
Ahhhh, OK that makes sense thank you.
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Re: EL84 equivalent

Postby crgfrench » Sun 04/28/19 12:18 pm

geoff 1965 wrote:
Sat 04/27/19 7:39 pm
the single input jack goes into both triodes of the preamp tube "parallel" and the concentric volume pot lets you control both triode signals seperately i.e. you can use one triode or blend them together,it's the same as using a jumper between the inputs on the old plexi marshall's blending the normal channel with the bright channel.
1959u.gif
That makes sense for the schematic you posted, with different bypass caps and bias resistors for the 12ax7 cathodes. The schematic I posted shows a common cap & resistor there so i was scratching my head. He must have them separated. That makes sense thank you.
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Re: EL84 equivalent

Postby geoff 1965 » Sun 04/28/19 12:45 pm

yeah the schematic is the marshall plexi superlead which he's used for the preamp of the mini superlead in the video,i've sent him an e-mail asking which output transformer he used for the ecl86's.
i also subscribed to his youtube channel,he obviously" knows his onions" and has great tone with the amps he's built!
p.s. Mark has very kindly replied and he used power and output transformers from a Hammond AO-44 organ amp.
here's a schematic of a conversion showing transformer numbers.
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Re: EL84 equivalent

Postby crgfrench » Mon 04/29/19 6:24 pm

I've been binge-watching Uncle Doug, here's his tutorial on the AO-44: https://youtu.be/NX8nWO3tkF0
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Re: EL84 equivalent

Postby JMPGuitars » Tue 04/30/19 5:33 am

crgfrench wrote:
Mon 04/29/19 6:24 pm
I've been binge-watching Uncle Doug, here's his tutorial on the AO-44: https://youtu.be/NX8nWO3tkF0
Please don't, or at least be careful. He gives some ok advice, and a lot of bad or dangerous advice.
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Re: EL84 equivalent

Postby crgfrench » Tue 04/30/19 12:56 pm

JMPGuitars wrote:
Tue 04/30/19 5:33 am
crgfrench wrote:
Mon 04/29/19 6:24 pm
I've been binge-watching Uncle Doug, here's his tutorial on the AO-44: https://youtu.be/NX8nWO3tkF0
Please don't, or at least be careful. He gives some ok advice, and a lot of bad or dangerous advice.
Really -- what are examples of dangerous advice he has given?
I get that nobody is correct all the time, but in the scheme of things Doug seems pretty good, thoughtful and honest.
I don't know him personally but he seems to be pretty good with amps.
Would you recommend any better youtubers? I appreciate the feedback!
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Re: EL84 equivalent

Postby geoff 1965 » Tue 04/30/19 5:41 pm

yeah i like uncle Doug for the way he explains the workings of tube amps in a way that's easy to understand if you're new to this,it's good that people like him take the time to draw out explanations,diagrams & video's for us to learn from.
D-lab and mr carlsons lab are both excellent and their background is electronics,but the key word here is "lab" just look at all the test equipment they have! i for one don't have an oscilloscope,signal generators and a machine to print of circuit boards! etc! etc!
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Re: EL84 equivalent

Postby JMPGuitars » Tue 04/30/19 8:11 pm

crgfrench wrote:
Tue 04/30/19 12:56 pm
Really -- what are examples of dangerous advice he has given?
I get that nobody is correct all the time, but in the scheme of things Doug seems pretty good, thoughtful and honest.
I don't know him personally but he seems to be pretty good with amps.
Would you recommend any better youtubers? I appreciate the feedback!
One example is a video regarding amp testing, and isolation transformers. He advised lifting the ground in a way that would absolutely kill you if there was a shock or fault of some kind. Another video I saw he was using regular scope probes wrong on purpose, doing what should only be done with high voltage differential probes. ...and I have no interest in his pets.
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Re: EL84 equivalent

Postby crgfrench » Tue 04/30/19 11:44 pm

JMPGuitars wrote:
Tue 04/30/19 8:11 pm
crgfrench wrote:
Tue 04/30/19 12:56 pm
Really -- what are examples of dangerous advice he has given?
I get that nobody is correct all the time, but in the scheme of things Doug seems pretty good, thoughtful and honest.
I don't know him personally but he seems to be pretty good with amps.
Would you recommend any better youtubers? I appreciate the feedback!
One example is a video regarding amp testing, and isolation transformers. He advised lifting the ground in a way that would absolutely kill you if there was a shock or fault of some kind. Another video I saw he was using regular scope probes wrong on purpose, doing what should only be done with high voltage differential probes. ...and I have no interest in his pets.
Thanks for the heads up.
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Re: EL84 equivalent

Postby crgfrench » Tue 04/30/19 11:53 pm

geoff 1965 wrote:
Tue 04/30/19 5:41 pm
yeah i like uncle Doug for the way he explains the workings of tube amps in a way that's easy to understand if you're new to this,it's good that people like him take the time to draw out explanations,diagrams & video's for us to learn from.
D-lab and mr carlsons lab are both excellent and their background is electronics,but the key word here is "lab" just look at all the test equipment they have! i for one don't have an oscilloscope,signal generators and a machine to print of circuit boards! etc! etc!
I learned a lot from all 3 of those and also from Rob Robinette's 5E3 website. I do have a Tektronix 453 scope which isn't really necessary for building amps; my signal generators are a strat and a Les Paul; and https://oshpark.com/ is my "machine" to print circuit boards. I watched one D Lab episode where he was resting the fingers of his left hand on the chassis while probing the components with his right after drinking that wine, I was a little nervous there but he didn't get zapped...
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Re: EL84 equivalent

Postby geoff 1965 » Wed 05/01/19 7:08 am

neat link! anyone can make a mistake no matter what their level of expertise,look at the tutorials & book's Gerald Weber has written yet watch this! deadly but this still makes me laugh!
https://youtu.be/3BEHIwzpiCM
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Re: EL84 equivalent

Postby crgfrench » Wed 05/01/19 11:29 pm

geoff 1965 wrote:
Wed 05/01/19 7:08 am
neat link! anyone can make a mistake no matter what their level of expertise,look at the tutorials & book's Gerald Weber has written yet watch this! deadly but this still makes me laugh!
https://youtu.be/3BEHIwzpiCM
I bought Gerald's EP2 Echoplex from him about 15 years ago, it's the one in his "Desktop Reference" book. Sold it about 4 years ago and wish I had kept it.
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Re: EL84 equivalent

Postby JMPGuitars » Thu 05/02/19 6:15 am

geoff 1965 wrote:
Wed 05/01/19 7:08 am
neat link! anyone can make a mistake no matter what their level of expertise,look at the tutorials & book's Gerald Weber has written yet watch this! deadly but this still makes me laugh!
https://youtu.be/3BEHIwzpiCM
Sure, everybody is probably human. But giving bad / dangerous advice isn't the same thing as making a mistake. When you make a mistake, in these situations, you're usually only putting yourself at risk.
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