Simon Dorn
Well-known member
Last edited:
shar-vell Dan
Well-known member
That edited video means nothing.
DanTravis62
Well-known member
Yeah the top end changed each time you switched. It's especially apparent when you switch to 16ohms
Simon Dorn
Well-known member
Watcha wanna say? Dude.
That edited video means nothing.
https://hughes-and-kettner.com/news/ohm-cooking/
Simon Dorn
Well-known member
And also the Mids. Did you read the Article? I found it pretty enlighting. https://hughes-and-kettner.com/news/ohm-cooking/
DanTravis62
Well-known member
Yes, the mids changed, but the reason I mention the high end, is because generally speaking guitar amps have decent EQ controls for the midrange
I.E., any changes through "ohm cooking" to the mids could possibly be accounted for with EQ
That huge change in top end sizzle i'm not so sure about - it sounds higher in frequency than most presence controls i've used
As far as the article - I love Hughes and Kettner. They're one of my favorite brands ever. But just like when mesa said it, I'm not mismatching my cabinets lol.
I've been on the inside of too many tube amps changing transformers because of shit like this. My buddy had a bandmaster head that he ran (unmodified!) into a 16 ohm 2x12 - and I have more blood, sweat, tears, and solder inside that chassis than any other in my lifetime
He thought it sounded good mismatched. It blew up transformers (twice) electrolytics (countless times) and even melted some beautiful NOS RCA tubes
Simon Dorn
Well-known member
Yeah, sure. I don't mismatch. Only when i pulled 2 Tubes and left the speaker cable in the 8ohm output where it's supposed to move to the 4ohm output with an 8ohm Cab. But then i really cranked it without problem. I liked it better than in the 4ohm output.
DanTravis62
Well-known member
If it's a "5.33 ohms" situation like in the article, I can totally understand that
Or even running it mismatched, if that's what you like the sound of
However, it should be mentioned that there could be consequences to this haha
Simon Dorn
Well-known member
Fair enough.
dead-pan
Well-known member
I will sometimes miss match just as I sometimes use a variac. I would never advise someone to do the same as there is potential risk.
Simon Dorn
Well-known member
I think we're all old enough to make our own decisions.
dead-pan
Well-known member
Absolutely, as long as the person isn't blind to possible issues.
Simon Dorn
Well-known member
Regarding the Topic. I found a Post by the "Unspeakable" on a German Forum. Here's the Translation:
"
Under-matching increases the current flow in the transformer and through the output tubes by up to 1.4 times the usual value per step mismatch. This wears out the end tube cathodes more quickly and can overload the thin primary windings of the transformer.
Overmatching reduces the current flow between the cathode and anode within the end tubes, but the screen grid now absorbs considerably more electrons, which can lead to it being overloaded. Furthermore, in extreme situations this can lead to voltage flashovers within the end tubes in the pin area and at the tube socket.
Even if others have been practicing mismatch for years without any problems and Mr. Smith is at least partly of a different opinion, I can only advise against mismatch - whether up or down! Especially because even 'correct adjustment' is already missmatch enough Why?
Because no loudspeaker has a flat impedance curve over its entire frequency band! At the resonance frequency, the impedance is approx. 3-5 times higher than the nominal impedance, which is usually measured at 400Hz. From this frequency onwards, the impedance of each speaker rises continuously with increasing frequency and at 3kHz has reached approx. twice the nominal impedance and at 10kHz approx. three times the nominal impedance.
By the way: I also used to answer the question about permissible mismatch somewhat carelessly with something like: “Any healthy tube output stage can tolerate a step mismatch up or down!” But in the meantime I have distanced myself from this!
Larry"
https://www.tube-town.de/ttforum/index.php?topic=8930.0
"
Under-matching increases the current flow in the transformer and through the output tubes by up to 1.4 times the usual value per step mismatch. This wears out the end tube cathodes more quickly and can overload the thin primary windings of the transformer.
Overmatching reduces the current flow between the cathode and anode within the end tubes, but the screen grid now absorbs considerably more electrons, which can lead to it being overloaded. Furthermore, in extreme situations this can lead to voltage flashovers within the end tubes in the pin area and at the tube socket.
Even if others have been practicing mismatch for years without any problems and Mr. Smith is at least partly of a different opinion, I can only advise against mismatch - whether up or down! Especially because even 'correct adjustment' is already missmatch enough
Why?Because no loudspeaker has a flat impedance curve over its entire frequency band! At the resonance frequency, the impedance is approx. 3-5 times higher than the nominal impedance, which is usually measured at 400Hz. From this frequency onwards, the impedance of each speaker rises continuously with increasing frequency and at 3kHz has reached approx. twice the nominal impedance and at 10kHz approx. three times the nominal impedance.
By the way: I also used to answer the question about permissible mismatch somewhat carelessly with something like: “Any healthy tube output stage can tolerate a step mismatch up or down!” But in the meantime I have distanced myself from this!
Larry"
https://www.tube-town.de/ttforum/index.php?topic=8930.0
conanthewarrior
Member
Listening through my monitors I thought that the 4 Ohm setting sounded a bit more muddied, and that the 16 Ohm setting sounded clearer but I can't put my finger on what, but sounded like something was almost missing if that makes sense?
conanthewarrior
Member
Wait, on your amp you can pull 2 tubes and it will still work? Is this a feature of some amps and if so could you explain it to me? Sorry if it is a basic question but I am new here and trying to learn more about tube amps
ners
Well-known member
I still need to watch that video, but Dave Friedman has said multiple times that a one click difference (eg. 8->16) won't cause any issues (he didn't discuss tonal changes).
Simon Dorn
Well-known member
Did you read the Article i posted?
Simon Dorn
Well-known member
Translate, Copy&Paste from here: https://www.gitarrebass.de/workshops/faqs-zu-marshall-amps-alle-folgen/
"I know some guitarists who have removed two of the four output tubes from their 100-watt heads to reduce the output to 50 watts. Do such measures make any sense at all or is it dangerous for the amp in any way?This is a very common tuning for Marshall heads. However, there are a few things to keep in mind. First of all, it is important that you only remove the two outer or two inner tubes at a time, because this is the only way the amp really stays in so-called push-pull mode. Since the primary impedance of the output transformer is designed for four tubes, you should halve the impedance at the output. Transformers, as the name suggests, "see" transmission ratios and not fixed impedances. For example, if you play a 16-ohm speaker, you should select the 8-ohm tap at the output with two output tubes, and for an 8-ohm speaker you should select the 4-ohm tap. Many Marshalls also have a voltage selector switch that allows you to change the output impedance. Since the number of "consumers" is reduced by two missing tubes, the voltages on the output tubes could increase slightly. It is therefore also advisable to check the quiescent current. However, this usually only increases slightly."
conanthewarrior
Member
Yes I did read the article, so less mids with the 4 Ohm output would explain the kind of muddiness I guess.
Thank you, I have learned something new! I didn't realise on the bigger amps you could just pull two power tubes to halve the power of the amp, thats pretty cool!
