Production 5751/EL34 Amp: Schematic/Design Deep Dive!
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- Опубликовано: 19 июн 2024
- This video I go over the schematic of the power supply and the amp and try to explain how everything works/is related. Hope this helps people understand what's going on inside this amp!
Here a link to the final schematics and the BOM:
www.skunkiedesigns.com/el34di...
This is my video on how a tube amp works:
• How do Vacuum Tubes Work?
Link to the GFI wall wart:
amzn.to/43Y3zMS
And the Hakko Soldering Station:
amzn.to/3Un1BCh
This is the build series of my open source production amp. This amp is available for sale in limited quantities, contact me for info. This is a VERY detailed step by step, wire by wire, solder joint by solder joint video series meant to serve as the instruction manual for assembly.
You can send me links and messaged at:
www.skunkiedesigns.com/contact
I have a new personal email: stephe@skunkiedesigns.com
Here is my Patreon, as well as the donation page at my site, if you feel so inclined to help fund some of the future projects for the channel!
www.patreon.com/user?u=87080658
www.skunkiedesigns.com/donate
Here is where you can buy T-shirts and other Merch with my fun logo.
skunkie-designs.myspreadshop.... 
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I appreciate your work, I've been building amplifiers since the 60s, I still have the same enthusiasm and your videos give me more motivation, gratitude for everything!😇
I so appreciate how well detailed you explain what and why. I’m not a newbie as far as listening to tube amps I love the detail of instruments the airy sound and imagine I hear. I’m so thankful your experience an explanations . Thank you so much skunkie. Watching one more time for today I’m sure I’ll watch again.
Fantastic content! I believe that might be the most concise and quick schematic walk through I have seen anywhere!
That local feedback loop between the plates is a very nice solution...........it was used by Werstern Electric in many of their amps long ago...changing the value of the resistor can be optimized to your speaker choice .
I used it on some amplifiers ...example a 6V6 PP driven by a 6SL7 with 470 ohm resistors in tyhe FB loop between plates , and no use of global FB ....sounds very muical and open ..
Some WE amps used also a capacitor ( 0.1 - 0.22 µF ) in series with the resistor in the FB loop to avoid DC signals to enter the FB loop to the dirver tube.
If the OPT is good , by it's design this amp can have a very nice soundstage filled with music
avoiding the nasty harm that regular FB does to little signals and small dynamics.
The amp will also respond clearly to the choice of components and the quality of the ubes ..so tube rolling might be interesting to obtain the synergie one is looking for.
A very nice project for a DIY beginner and even for a skilled experienced audiophile
PS: When someone only needs fleapower on very sensitive speakers , easy to convert to triode mode , connecting the screen to the plate of the EL34 ( with resistor ) ........The EL34 ( as well as an EL84/6BQ5 ) works very well in triode mode....UL and penthode .....
RCA.....Sylvania GB ..and others sound very good as an input tube......finest tubes are the triple mica /black plates .....rare but one can find ONE .....witk a little luck.
Beware a 5751 sold as new or so claimed old stock measured good as a ECC83/12AX7 is in fact a used and ead tube.............So take attention to sellers that pretend the tuibes test as new ( but is in fact end of life ).....especialy on Ebay....
Kind regards
Im a tube amp builder newb, that said Im very curious about having a dc blocking cap in the fb loop! Do you by chance remember the model of we amp? Love to dig up a schematic to see what they did! Great video and fantastic response!
I would add, if you change this to a triode output, I would remove the Schade feedback resistor. It's likely no longer needed.
@@AudioFanMan I have schematics of those WE amplifiers with the capacitor in that particular FB loop .......some studies more recently on SS amps showed the negarive influenhce by injecting DC into the NFB...
In case of the WE amps.........what is substantial is that they do not use global FB .....and distortion levels on small signals go under 0.01 % ....NF on more current SS creates hard distortion ..........very low on big signals but importantbon very small signals ...in French we call this " Distortion dur "
IF you please I can let you know the ISSBN number on those books...
WE was far ahead in tube technology at that time and old amplifiers are sold for horrendous high prices even when rusty ...
It is asthonishing gthe freedom one has by building these amplifiers oneself ............remember that amplifiers that let the music flow freely are like the beauty of wild horses versus those who are controled on horse shows to please the public..........
Also one need thse kind of loudspeaker that let express the musicality of these beaiuties.
You're a happy man to build yourself .........and keep in mind to BELIEVE your ears and soul rather than numbers............
Kind regards
Very good explaination of a tube amp schematic.
Great work!!! I love that little amplifier. I may build one.
Thank you! Appreciated the nfb explanation
Glad it was helpful!
Received my transformers today for this project! Need to order a power switch and an input selector, and a volume knob. I am excited to build this!
Good luck!
Great video 👌👍
Thank you! Cheers!
I used one of those power switcher/GFI things to turn a hot-air popcorn popper on/off since it had no switch of its own. I eventually noticed the switcher was hot (always) so I tossed it. It may have been a different design.
That appliance likely pulls a lot more power is the difference here.
Howdy.
I would say using the volume control pot. as shown is a waste of good gain.
I suggest controlling volume by controlling neg. feedback from the input tube's anode to the input tube's grid with a pot. This would make use of all the gain to minimize distrosion.
Regards.
You realize there is no negative feedback for a reason and I have no interest in removing all the distortion. If I did, I would just buy a SS amp. BTW I've never seen an amplifier control the volume in this way, adding this much NFB turns the amp into an oscillator.
Thank you for the safety advice
Had not given it proper consideration…yikes
If people will spend $70k on an audio cable you can bet I will get the best GFCI plug-in outlet which won’t really cost very much thankfully 😅
I have a healthy respect for High Voltage Rock ‘N Roll
Thanks for the overview! I noticed a manufacturer that has their main circuit ground point isolated from the chassis and earth ground with a capacitor. Do you think this is unsafe or a good way to avoid ground loops?
I haven't found the need and don't like the idea of what is basically a floating ground. Especially if they don't have any of the input/outputs grounded directly. I always try to think worst case and don't think any part that can have human contact isn't zero ohms to chassis/earth.
Nice looking circuit. Could include a triode switch too quite easily.
Having the cathode resistance in the driver stage unbypassed also improves the effectiveness of the plate feedback by increasing the Z of the 12ax plate.
And it sounds better :)
@@SkunkieDesignsElectronicsWould the unbypassed cathode resistor be a good option for the Reisong A12 modification?
Note I am only "unbypassing" a portion of the total cathode biasing voltage.
Hello, Can a 650 Ohm cathode resistor be used so that the EL34 is not so at the limit of its power?
Sure, but these are $20 tubes, what are you trying to preserve? Expect more distortion and it won't sound as good.
Thank you for sharing this! I'm planning on building this amp. I noticed you are using 2 watt metal films. I have a large stash of old Dale metal film resistors, mostly in 1/2 & 1 watt sizes I would like to use. Do you think 1 watt plate & B+ dropping resistors would be sufficient & then I could use 1/2 watt everywhere else (other than the higher wattage power supply & cathode resistor)? Thanks!
That resistor in the power supply needs to be a 5W. I think I have supplied enough voltages to calculate if those will work elsewhere.
I would be interested in how the quality of the output transformer translates in to the measurements, Very good video by the way.
Coming soon
Can you replace the 360k ohm feedback resistor with a linear potentiometer, adjust to suit your system then either lock it in place or measure the value and replace with fixed resistors?
I haven't done this, my worry is finding a pot rated for that voltage/wattage. I did do an amp once with a center off DPDT switch to be able to listen to zero feedback or two different values.
Will changing the value of the 1.2k input resistor on the 12AX7 change the sound of the amp at all?
Nope.
I'm currently building an EAR 834 clone which has solid state rectified power for 12.5V heaters and 280V B+ line. What woul be the pro/con vs a tube rectified set up?
I honestly don't see any reason to use a tube rectifier on a phono stage. I mainly use then for the slow B+ ramp with higher current output tubes, especially run as hot as I tend to run them.
Hi, can i use local feedback if i connect the amp on triode mode !so do i have improvement on ringing square wave!We can see this on the kt 88 abdella amp vs blueglow .have you put local feedback resistor on the kt 88 ,it would be interesting to see on your oscilloscope square wave 1000 hz and 10000 hz cause you dont have vidéos for testing this amp .
You can but I have found from listening tests, very little if any local feedback is needed or desired if you triode strap the output tube. Doing so ends up with a very dead sounding amp irregardless of scope testing results
ok the ear is the best judge always
@@SkunkieDesignsElectronics
sorry, Stephe, I know You took the schematics from the net but I have seen something: mega is with capital m, mili is coded with small m
I didn't take the schematic from the net... Why would you say that?
@@SkunkieDesignsElectronics sorry, my bad