Hey folks
I am building a VK-like amp cab and plan on installing my cvr inside. I know there will be a impedance issue here...but I liked the 3 x 10 in my VK so is this about the same idea or will it really cause trouble ? The vk also has a 4 ohm OT...No?
Btw..I did add a nfb loop...switchable.
cvr with 3 x 10 idea
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Stevem
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Re: cvr with 3 x 10 idea
Some basic facts for you to ponder here!
1) any time you mismatch loads on a output transfomer you will drop off 1/3rd of the amps available wattage, this could be good,or it could be bad dependnt on how loud the amp is.
Now temper what I just said with what's below!
2) running a higher impedance load on a amps lower impedance tap will make for a good chance to arc over the windings in the OT when the amp is driven hard.
3) a mismatch of a lower impedance on a higher tap will call for the output transformer to handle far more current than it was likely designed to handle.
4) A mismatch of a lower impedance on. Higher tap will use up the output tubes faster, the opposite is true the other way around impedance wise!
Note that 3 16 ohm drivers wire in parallel is a 5.3 ohm load, and 3 8 ohm drivers in parallel will be a 2.6 ohm load, so it's a toss up as to what would be safer in terms of OT life, if it where me I would first install a new OT that is rated for 10 watts more than the amp can muster, and also note that today'mass produced amps are never up to snuff power wise, if they are sold as a 40 watt amp they are lucky to make 32 watts!
1) any time you mismatch loads on a output transfomer you will drop off 1/3rd of the amps available wattage, this could be good,or it could be bad dependnt on how loud the amp is.
Now temper what I just said with what's below!
2) running a higher impedance load on a amps lower impedance tap will make for a good chance to arc over the windings in the OT when the amp is driven hard.
3) a mismatch of a lower impedance on a higher tap will call for the output transformer to handle far more current than it was likely designed to handle.
4) A mismatch of a lower impedance on. Higher tap will use up the output tubes faster, the opposite is true the other way around impedance wise!
Note that 3 16 ohm drivers wire in parallel is a 5.3 ohm load, and 3 8 ohm drivers in parallel will be a 2.6 ohm load, so it's a toss up as to what would be safer in terms of OT life, if it where me I would first install a new OT that is rated for 10 watts more than the amp can muster, and also note that today'mass produced amps are never up to snuff power wise, if they are sold as a 40 watt amp they are lucky to make 32 watts!
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: cvr with 3 x 10 idea
Your claim seem light in "facts". Could you please quantify your claims?Stevem wrote:Some basic facts for you to ponder here!
Mismatches are quite common in tube amps - especially since the impedances are dynamic with respect to frequency.
Re: cvr with 3 x 10 idea
Fact is, you can do a mismatch if you think it through and do some math.
Most fender amps with a pair of 6L6 tubes have an OT with an impedance of 4000 to 4200 ohms.
5.3 / 4 = 1.325
Connect the 5.3 ohm load to the 4 ohm tap and you have, 1.325 * 4000 = 5300 ohms. I don't see a problem with that. In fact, I think it would sound nice and creamy smooth.
Did I done my maths right?
Most fender amps with a pair of 6L6 tubes have an OT with an impedance of 4000 to 4200 ohms.
5.3 / 4 = 1.325
Connect the 5.3 ohm load to the 4 ohm tap and you have, 1.325 * 4000 = 5300 ohms. I don't see a problem with that. In fact, I think it would sound nice and creamy smooth.
Did I done my maths right?
What?
Re: cvr with 3 x 10 idea
It seems that all I read about the notorious mismatch that it only adds versatility to the amp project I am working on. I intend make it switchable from 3 to the standard 2-10. That way I can still claim all the headroom that I gain by Adding the nfb loop on the cvr..which is also switchable.. doing even more math...then I will get even more early breakup when cvr mode and 3-10 mode is activated. Wouldn't that be a treat guys ??? 
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tele_player
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Re: cvr with 3 x 10 idea
In with you on this. 2.7 ohms isn't enough mismatch to worry about on that amp.bieworm wrote:It seems that all I read about the notorious mismatch that it only adds versatility to the amp project I am working on. I intend make it switchable from 3 to the standard 2-10. That way I can still claim all the headroom that I gain by Adding the nfb loop on the cvr..which is also switchable.. doing even more math...then I will get even more early breakup when cvr mode and 3-10 mode is activated. Wouldn't that be a treat guys ???
Robert
Re: cvr with 3 x 10 idea
The sin starts...
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Re: cvr with 3 x 10 idea
Raw amp cab...Now the hard work begins...
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