It's simple, but not really minimal in my opinion. Minimal to me sounds more like a low parts count, no whiz-bang build. Granted that the SSE isn't all that complex, there is something to be said for a basic build. Hard to beat the SSE for many aspects though.
Last edited:
my versions of simple and minimal amp circuit:
http://www.diyaudio.com/forums/tubes-valves/302531-my-6e5p-amps-spud.html
http://www.diyaudio.com/forums/tubes-valves/302531-my-6e5p-amps-spud.html
Well, just noticed that the last amplifier mentioned had its thread locked due to unsafe building practice (lack of isolation transformer!?) Which is a clear violation of forum guidelines. Please do not build that amplifier!
Hopefully the poster can include a power supply schematic if he reposts it, as it was a clever design aside from the safety issues.
Expounding on my original reply however, take what I posted even more simple, use an ECL82 or similar triode/pentode tube to save yourself another socket, and it allows most of the wiring to be done at the sockets themselves.
If you like push pull you can do up a nice little 1-1.3w or so build using the design I posted in my signature- it uses a 6SN7 as the power tube. You can easily beef up that design to use a larger dual triode such as the 6AS7 with the relevant changes to the PSU. That would get you 8-10 watts depending on execution.
Hopefully the poster can include a power supply schematic if he reposts it, as it was a clever design aside from the safety issues.
Expounding on my original reply however, take what I posted even more simple, use an ECL82 or similar triode/pentode tube to save yourself another socket, and it allows most of the wiring to be done at the sockets themselves.
If you like push pull you can do up a nice little 1-1.3w or so build using the design I posted in my signature- it uses a 6SN7 as the power tube. You can easily beef up that design to use a larger dual triode such as the 6AS7 with the relevant changes to the PSU. That would get you 8-10 watts depending on execution.
There's no such thing as "best" but here's a fairly simple, low parts count, amp I built using a 27 as input and a 6A5G output. I wanted to build a true SET, not a triode strapped pentode. The tubes were chosen to hopefully get close to having all the sonic advantages of using DHTs like the 26 and 2A3 while still being able to use basic AC heating.
Because it uses indirectly heated tubes it doesn't require any special efforts to deal with hum. Most designs using directly heated triodes require DC heating of some sort which can add to the complexity quite a bit, depending on the method used.
Perhaps I'll post more details about it in a separate thread sometime.
Last edited:
The post I referenced has disappeared it seems- here is the original thread I referenced- http://www.diyaudio.com/forums/tubes-valves/309434-6v6-6aq5-pp-integrated-amp-w-ccs.html
Ah the RH84, IME, that is a very simple but very good sounding amp. If you spend money on better output transformers the amp will also produce better sound. The biggest thing is to make a very good power supply, which is also true of any single ended amp. There has been many, many builders of this amp and if that is any indication of worthiness, then you would be in good company.
Here is the link. RH Amplifiers: February 2013
I obviously like this idea a lot, I'm not inclined to use a bridge rectification though, I think I would prefer using a rectifier tube. I want to keep it old school 😉
Questions:
-What's an "AA" Champ?
-Are there any sort of "classic" or "timeless" amp designs from the 50's or early 60's like in guitar amps? Does the hifi "holy grail" of tone exist?
I just finished building one of the "holy grails" of guitar amps, a true classic. And it is an awesome amp, can't be beaten
just realized that nobody responded directly to this. The AA champ is pretty much the AA764 Fender Champ guitar amp. 1-12AX7, 1-6V6GT, and 1-5Y3GT rectifier.
Very easy to modify this into a workable design for HiFi use, simply chop out the first gain stage, remove the tone stack, and like PRR said, bring the power supply voltage down to around 300-320 volts, with a corresponding change of the output transformer to around 5k from the more common original 7.5k.
Something like this should result, and would work well if a few watts will do-
SE-6V6 Amplifier
Use a 12AX7 if you must, But I would like to see a 6SL7 or 12AT7 here, especially when using negative feedback to improve the damping factor (tetrode/pentode amps can sure use it) as well as linearity. I have a soft spot for the 6SL7 especially, but a 12AT7 may be a better choice here so it can run a bit more current, which will make it easier to drive the 6V6 easily. Could even do it with an EL84 if you wanted, a little easier to drive and a bit smaller physically, adjusting parts values to suit. If you do that, you end up with something like the RH84-
RH Amplifiers: RH84 amplifier - revision 2
I've built a few variations of these (mostly 6V6) over the years, and they are a very, very nice, simple, quality amplifier that really lets the tubes shine. If around a couple watts max will work for you they can even be set up as a triode connected build, or even made switchable for playing around later. I'm not that much of an SE guy, but I was really happy with each one I put together and highly recommend putting together something similar. For the PSU a tube rectifier will work fine, 5Y3GT or 5AR4 would work well, as would a bridge rectifier. A few caps and resistors would work well due to the mostly constant current draw, and be a bit cheaper than a choke.
The schematic has been re-posted with a proper isolation transformer. I think he should give it a serious look.
73,
Randy AB5NI
Just have to disagree. Simple but fundamentally flawed. Better designs are available.
Shoog
Replace the driver triode with a pentode (or change it to use cathode feedback) and change out the CCS for an LED array, and now we're talking! I don't personally think the RH84 is the best, but they do sound pretty nice.
In my earlier post the RH84 was only mentioned due to similarity and simplicity. There are better ways to do things, yes. Good basic bones in the design to start and swap some things up.
All the versions of SE amps I've built look mostly like the HiFi champ I described, and they really are hard to beat. Maybe it needs a catchy name to catch on better? Perhaps I'll start a new thread on the "Champion" SE Amplifier 😀
You have described the essence of the issues involved. If you only have a triode driver then cathode feedback is by far the better approach than the RH concept, and its just as simple but requires careful modelling to get the most power out. Built a very nice EL82 spud amp on just such a principle and it sounded much better than I could ever have anticipated within its limited power range.
Also a CCS has no place in such a design or any other SE design for that matter.
Shoog
Care to elaborate on that statement?
Is there a technical reason, or is this a personal preference?
I agree with Shoog, the CCS in an SE is somewhat trendy nonsense, a simple R+C gives rather that nice soft clipping sound.
The LED array would be same as a zener, which potentially could make a benefit of keeping the bottle a little bit cooler, but you gotta carefully audition it and pick a precisely right one (not overdo).
I am wondering how a choke would do instead of R+C.
i am clueless as how a SE El84 / SE 6sn7 can be of any use to anybody.
I strongly believe it would sound worst than a 15 $ transistor amplifier
I strongly believe it would sound worst than a 15 $ transistor amplifier
Well, good thing we have ways of engineering one to work well at low distortion then, huh?
SE Triode EL84 can be a pretty linear (for what it is, push pull is no doubt a bit better in the engineering side of things for distortion) and supply a couple of easy watts that sound very nice when done right. Pentode mode can get more power at good distortion levels if you use some feedback and tailor it all to work well together.
SE 6SN7? Not sure why anyone would do that personally, and I'm not sure I've seen any references to one posted. Might be a neat idea for headphones if a half watt or less would do.
I'm not a huge fan of SE, but it can be made to work within it's limitations by a competent engineer. Push pull is a bit better for most uses of course, but has it's own design considerations to deal with.
Cathode loads for SE can be an interesting fistfight among a ton of audio guys. Here's my take on things based on my research and first hand experience-
The CCS will give reduced headroom (minimum dropout voltage of the CCS will limit swing) and limit the possible output power, even if you bypass it. Some will even oscillate under overload. The only true benefit I see is providing a steady bias current that doesn't change over time, but I feel the disadvantages outweigh that "feature" in this application. For the cathode you want the load constant in voltage, while allowing the current to vary with signal- a CCS prevents that when you deal with higher current types of applications.
A resistor/capacitor combo would be better in this sense, but on heavy signal you will encounter blocking distortion as the cap does its thing. It works fine most of the time, as music doesn't tend to have a huge crest factor, so the issue isn't usually a huge deal. If you want to have some real fun in the olde-schoole sort of way, try cross-coupled garter bias...
A nice low-impedance LED array (series/parallel to give the desired current handling and voltage drop) will be a great solution, as it will vary much less over signal in practical use, and will not require (or benefit from) a bypass capacitor, and therefore will prevent blocking distortion from the capacitor charging/discharging in use. It will show a positive and measurable difference in THD levels. Take a look at Sy's Red Light District Amplifier for some engineering behind why it's a good idea, and how well it works.
Even better? Ground the cathode and go fixed bias. You need to make an adjustable bias supply, but that's no big deal usually. Admittedly I'm not a big user of fixed bias, as it doesn't have any way to self limit itself in the event of bias drift over time, as can be seen in some old and/or gassy tubes.
Never really played with choke loading anodes or cathodes, so I can't really comment on that idea.
My advice and reasoning are offered for your perusal, with no warranty expressed or implied. It's worth waht you paid for it. Use it as you see fit 😀
Last edited:
So, my ideas are on a new thread, for anyone interested. I don't want to further clutter the OP's thread with my ramblings 😉
The Champion SE amplifier.
Give it a look 😎
The Champion SE amplifier.
Give it a look 😎
- Status
- Not open for further replies.