The Amp Garage

Ciao Sergio, That one is the standard OD100. I've had the SE and it was written in the front. I've played a Classic plus and it was written in the front. There are variations on the circuit during the years, but the very basic rule is a classic Fender clean channel and a lead channel with two cold s...

EL34 can produce power output far exceeding its dissipation rating and KT66 really can’t reach it. [OMISSIS] 6L6 tubes have several ratings but really output the same wattage. I know the voltage ratings change but in a test between metal body 6L6 and a 6L6GC, they have basically identical output sh...

Good catch pdf64!
The one in my mind was european, but then it isn’t the only one!

LOUDthud,
thanks for the FCC explanation.I thought UL was covering the emissions too. We have something similar in Italy and EU as well, but I don’t recall the name.

Maybe the thread can be split? We are going OT.

In any case, to test a SMPS with SE amps, these can be used:
https://it.aliexpress.com/item/1005003572385033.html
https://it.aliexpress.com/item/1005003138732085.html

Hi Dave, i run them at 340V B+ with 8k Raa and 23% UL, source followers DC coupled to the grids of the output tubes to reach AB2, plus a local feedback to triodize the curves (similar to the other thread about the 360k amp). Here below the loadline and the curves with UL (but without the local feedb...

I do remember another amp of mine does overdissipate the screens. EL34s with 6.6K OT, 470V HT, Choke but 2.2K screen grid resistors. I think it runs the screens at 12W flat out and the limit for EL34s is 8W. Komets must be even worse given they use 1K screen grid resistors with a choke and 5.2K OT!...

R.G., just curious, how hard is it to get an SMPS past the FCC and possibly UL ? If a DIYer made one that had significant emissions, would there be any legal consequences ? I clearly remember a commercial guitar tube amp with SMPS but I cannot recall which one it was. Sold worldwide, so CE and UL c...

In PP amp you dont need too much filtering at all to avoid hum at the output. It is enough resistor 300-500ohm between Ub+ and Ug2 node. Noisewyse I agree, but then the amp will become very sensitive to the volume you play at. I've done some tests and (also depending on the loadline you have chosen...

I can't tell you how much blow back I have received over the years for proposing SS diode replacment/updates in tube amp power supplies, using MOSFETs in tube amps and so on. I still have a file collecting some of the most frantic ones somewhere. :D I can imagine, because every time I propose a des...

Hi Aurora, can I ask you to please elaborate more the "Gyrators has nothing to do in power supplys"? As you know they are widely used on many SE designs of valuable designers to replace chokes with good results, lower costs and weight. It isn't the only solution, of course, not the total panacea for...

Hi Phil, it is absolutely NOT my intention to start any flaming. If I seemed “strong” in my posts, it was not my intention to do it, and re-reading me frankly I don’t see it, but could be me. PS I'm not in disagreement with what he wrote, I just proposed a possible solution to the ripple vs sag... s...

Frankly I don't understand this approach R.G. Using words like "what do you think it is" is a very aggressive and trollish approach. May I ask you the reasons of this rude approach? The energy stored (so released, minus efficiency) is half the inductance multiplied the squared value of the current. ...

Real inductors store, then release their own energy. Gyrators take energy from another power supply and actively take it in and let it out to fake the operation of a real inductor. They don't store their own power like a real inductor does. If we consider just the screens, there's no need to have a...

By "bigger" you mean "stiffer"? Yep, that could even be an SMPS and avoid the gyrator (and be lighter and cheaper as well). Looking at the current you set for the first node I understand it is a 50W amp. Indeed as you stated, simulation shows that specific result because of the parameters you set. S...

Once you suppress ripple enough, you get dramatically diminishing returns on ripple audibility. I fully believe that "sag" is ... something... , but I suspect that it is hard to quantify, and even harder to design for. What about a gyrator just after the rectification to eliminate the ripple (cheap...