Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Misc Schematics and Layouts => Topic started by: Taerix on April 17, 2022, 10:06:27 pm
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So Im Looking top get into the hobby for building amps. and I'm sure that i am biting off more than i probably should on my first project but ive found the schematics on this site (and a few different ones).
Has anyone built an Uberschall clone from schematics that are correct? these all seem to be different. this is the most laid out set i could find but for some reason they are set up with 12ax7's instead of EL34s that are natively in them, Also does anyone have any recommended reads or youtube series that are worth digging into to learn more about building and the basics?
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This Bogner is an incredibly difficult complicated amp. If this is truly a 1st build for you, I would respectfully say you have little to no chance being successful with this project. I've probably built close to 30 different amp designs (including some high gain amps) and I would be very very hesitant to take this one on.
As a 1st project, I would anticipate that it would not work at all at start up OR you would have a ridiculous amount of noise at idle (when not playing) OR severe oscillation problems. There are 1001 things that can go wrong.
The first build I did ended up actually having the most difficult trouble shooting problem of any amp. I spent almost every weekend for 2.5 months trying to solve it (which I was finally able to do). 15 yrs later, the last significant trouble shooting problem I had took me almost 20 hrs to find and resolve.
On top of that, building your own amp typically is just as expensive (or more expensive) than buying a used version of one.
And if you don't know what you are doing, you can easily get shocked with lethal voltages.
Respectfully, Tubenit
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++ what tubenit says. He's absolutely right. So, if not an Uberschall,where to start? Take a look at Doug Hoffman's list of "kits" here: https://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&thispage=PartsListIndex.htm&ORDER_ID=!ORDERID! (https://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&thispage=PartsListIndex.htm&ORDER_ID=!ORDERID!). These are well designed with good documentation (see the Project Link for each), but you will have to make design decisions along the way and you will learn.
Reading suggestion: Merlin Blencowe's "Designing Tube Preamps for Guitar and Bass." You can read some of it on his website http://www.valvewizard.co.uk (http://www.valvewizard.co.uk) -- by far the best author for amplifier design at your level. Rich Kuehnel (https://www.ampbooks.com (https://www.ampbooks.com)) is next, but you will want to know what Merlin has to say first.
By the way, the EL34's are on the second page of the schematic in the driver section.
One question I have regarding this interesting design: why all the optocouplers?
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Reading suggestion: Merlin Blencowe's "Designing Tube Preamps for Guitar and Bass." You can read some of it on his website
Merlin truly is a wizard :worthy1:
I have seen that some Bogner amps are based on Marshall, if lower wattage is not a problem perhaps the 2xEL34 Hoffman Plexi 50 to get you the EL34 tone if your playing metal,
Rob Robinettes JCM800 design has an EL34 25w version with easy to follow layout drawings and tips on circuit tweaking etc,
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The opto-couplers are for channel switching in many cases. Channel 1 or 2 , clean or dirty.
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What helped me with the little knowledge i have is to draw the very amp i am actually building with expressch and also save old versions, since you may alter things and maybe cant remember what you did.
Also i have an excel sheet for the very amp to enter voltages into and it calculates current and plate dissipation automatically. So i dont drown in paper and feel much safer now.
Ymmv but i think this actually saves time, too.