UG Community @ Ultimate-Guitar.Com

UG Community @ Ultimate-Guitar.Com (http://www.ultimate-guitar.com/forum/index.php)
-   Guitar Gear & Accessories (http://www.ultimate-guitar.com/forum/forumdisplay.php?f=33)
-   -   Changing Impedance? (http://www.ultimate-guitar.com/forum/showthread.php?t=1607318)

AJScott 06-27-2013 01:01 PM

Changing Impedance?
 
Greetings UG members

I fancy buying myself an AMT Stonehead, it's a small lunchbox size 50watt solid state head that is relatively cheap and sounds pretty good, to take to band practice and for use at home so I don't have to use my normal head.

However the Stoneheads only output is 8 ohms, and my 412 Cab, which is a Line 6 Celestion Vintage 30 loaded cab, only takes 16 ohms mono and 8 ohm stereo. I don't fancy buying another cab just to run this through, so is there some device which I can place in the signal path between the Stonehead and my cab which will change it to a 16 Ohm impedance mono, so it will run with my cab or other cabs of other impedances

Thanks

Cathbard 06-27-2013 01:04 PM

It will run fine into 16 ohms but cut the maximum power to about 30W. No damage will be done.

311ZOSOVHJH 06-27-2013 01:05 PM

I believe with solid state amps you can have the head lower than the cab like that. Tube amps different story.

AJScott 06-27-2013 01:12 PM

Quote:
Originally Posted by 311ZOSOVHJH
I believe with solid state amps you can have the head lower than the cab like that. Tube amps different story.



It's like running a tube head without the cab connected? This can still affect some solid state heads aswell, it's not all about tubes but capacitors and resistors aswell.

AJScott 06-27-2013 01:19 PM

Quote:
Originally Posted by Cathbard
It will run fine into 16 ohms but cut the maximum power to about 30W. No damage will be done.



I will need more than 30Watts of power, even if it was a tube head.

311ZOSOVHJH 06-27-2013 01:41 PM

Quote:
Originally Posted by AJScott
It's like running a tube head without the cab connected? This can still affect some solid state heads aswell, it's not all about tubes but capacitors and resistors aswell.

Huh?


Here is the rule I live by:

For Tube amps:
Amp Head Ohms > Cab Ohms = Possible blown Power Valves and/or Output Transformer.
Amp Head Ohms < Cab Ohms = Strain on the Output Transformer, Power loss.
*Some amps can take a 1 step mismatch but not all.

For Solid State Amps:
Amp Head Ohms > Cab Ohms = Broken amp
Amp Head Ohms < Cab Ohms = Power change, no strain

AJScott 06-27-2013 01:54 PM

Quote:
Originally Posted by 311ZOSOVHJH


Amp Head Ohms < Cab Ohms = Power change, no strain



What would be the power change? 50Watts of solid state power isn't much as it is, i'd rather not lose power but get the whole 50 Watts if possible. Is there some piece of equipment that can change the ohmage?

mmolteratx 06-27-2013 01:57 PM

https://taweber.powweb.com/store/zmatch.htm

Seems kind of a waste though. Not much to be gained by going from 30-50W. Like a 2dB increase in volume, which is barely perceptible.

gumbilicious 06-27-2013 02:12 PM

Quote:
Originally Posted by AJScott
It's like running a tube head without the cab connected? This can still affect some solid state heads aswell, it's not all about tubes but capacitors and resistors aswell.


no, it's not like running a tube head without the cab connected. it's nothing like that at all.

some OLD and obscure solid state amps are particular, but the ones we come across for playing music are absolutely fine with a higher impedance speaker cabinet.

heed 311's post.

Quote:
Originally Posted by AJScott
I will need more than 30Watts of power, even if it was a tube head.


i am pretty sure you said that without even trying it. i could be wrong though.

i would recommend:

1) trying the amp with the 16 ohm output using all 4 speakers

2) trying the amp with the 8 ohm output using only 2 speakers

then compare the two and see if you notice any kinda real volume difference. it would be preferable to have a friend help you so you can perform this 'double blind' and not be persuaded by your bias.

then if those two options don't work.

3) spend money to fix the problem.

you see, one and two require no money or excess equipment to attempt. it seems you are ignoring the cheap options that are readily available to you.
Quote:
Originally Posted by mmolteratx
https://taweber.powweb.com/store/zmatch.htm

Seems kind of a waste though. Not much to be gained by going from 30-50W. Like a 2dB increase in volume, which is barely perceptible.


+1. not worth it unless he has money burning a hole in his pocket.

311ZOSOVHJH 06-27-2013 02:13 PM

Yeah, I can't imagine you noticing the difference between 30 and 50 watts anyway tube or solid state.

But then, I can tell the difference between Sovtek 6L6s and JJ 6L6. :D

AJScott 06-27-2013 02:36 PM

I think i'll try the head running into the cab, and see the difference, thankfully the other guitarist in my band has a cab of which I can run it at it's 8ohms so I can see how the power will vary. If I really think I need the extra power i'll buy that impedance matcher, thanks guys!

ExDementia 06-27-2013 04:02 PM

50w should provide plenty of power, solid state or not. My solid state RG100es never gets turned up past 4-5 for band practice and it's 100w -- which doesn't provide much more volume than a 50w would.

The only reason tube amps are usually louder than solid state is because of how they rate them. Your typical tube amp will push quite a bit more than it's rated for if you crank it up, while a solid state amp hits a ceiling and becomes unusable past it's rating.

311ZOSOVHJH 06-27-2013 04:31 PM

^ I think it has more to do with the way harmonics are perceived by the human ear that makes tube amps seem louder - but you may be right too.



:shrug:

ethan_hanus 06-27-2013 04:37 PM

Quote:
Originally Posted by AJScott
What would be the power change? 50Watts of solid state power isn't much as it is, i'd rather not lose power but get the whole 50 Watts if possible. Is there some piece of equipment that can change the ohmage?


Well, my Aracom DAG 150 can change input and output ohms, but it cost almost $1000. It's a nice piece of equipment though. :haha:

I've played around with SS amps enough, and I've run them with out cabs, with cabs with crazy ohms and such and nothing seems to really bother them, as long as they are cooled properly they usually wont get damaged by running them into the wrong ohmage cab.

Cathbard 06-27-2013 09:12 PM

You'll lose about 2 dB going from 50W to 30W which is almost inaudible. You're probably going to get a much larger increase from using a better cab with more speakers. Even that aside, if 2dB is a deal breaker, you are pushing a SS amp too hard already and you actually ............... wait for it .............need a new amp.


All times are GMT -4. The time now is 10:49 PM.

Powered by: vBulletin Version 3.0.9
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.