Gain difference between output impedance on Rocket

[showsii]

Hey everyone, Got a quick question about my rocket.

I was experimenting with different cabs and speakers and found that using the SAME speaker (vintage 30) there is a increase in gain,overdrive ect using a 16ohm V30 compared to a 8ohm V30. The 8 ohm V30 is nice and clean with crunch coming in about 11:00.


Any thoughts? Has this happened to you guys before?


Thanks in advance


Ian

[showsii]

Anybody?


I apologize if this is a stupid question. I am searching for a thread of similar interest, but if some one has it already it would be greatly appreciated!

Ian

[paulster]

Are you sure you've got your output taps wired in the correct order to the impedance selector, i.e. you're not using the 16ohm tap on 4ohm setting and vice versa?

[Cliff Schecht]

16 Ohm taps present the highest impedance and are thought to give better bass response. The idea is that more windings can handle more low end before starting to saturate (bass signals take more energy to reproduce). Haven't tested this myself though..

[showsii]

Are you sure you've got your output taps wired in the correct order to the impedance selector, i.e. you're not using the 16ohm tap on 4ohm setting and vice versa?

I will double check that right now!


Thanks

Ian

[showsii]

16 Ohm taps present the highest impedance and are thought to give better bass response. The idea is that more windings can handle more low end before starting to saturate (bass signals take more energy to reproduce). Haven't tested this myself though..

Interesting, learn something new everyday. (or everytime I get on TAG) When you say saturate do you mean overdrive? Are these words interchangeable in this context?

Ian

[Cliff Schecht]

I'm talking about core saturation of the transformer which is typically an unwanted thing in TW style amps. More windings yields a higher inductance which can support more power before the core saturates and starts limiting frequency response.

[showsii]

I double checked my OT leads going to my switch..

Am I right in saying the following..

Brown-4 ohm
Yellow- 8 ohm
Orange- 16 ohm


Is this correct?


Thanks

Ian

[Cliff Schecht]

You can measure this with a DMM. With no speaker attached, measure the resistance of the output jack (referenced to ground) with the selector switch in each position. 4 Ohms will be the smallest resistance (may take a bit for your meter to finally "settle" on a value), 8 bigger and 16 the highest resistance. Even most cheapo meters with really resistive leads can give you the right information as you long as you take all of your readings as relative (i.e. you know 16 is the highest and 4 is the smallest) and you give the meter enough time to settle.

[overtone]

Ian, double check against the diagram that came with the transformer especially if your meter cannot give you a clear reading.
I recall that you had the transformers from RJ, I think the colors that you listed above for the 8 & 16 do not tally with the Heyboers, but I may be wrong.
If you get really stuck there is a way to determine the ratios of the windings, let us know and we can walk you through that if need be.
When you are certain that you have no mismatch just take the tap which suits you. If you search for it online you will find endless heated discussions on which tap is "best", what ever best may be!
Trust your ears.

[guitarsnguns04]

if its heyboer from rj it should be:
16-yellow
8-orange
4-brown

from what im reading in the posts your 8 and 16 are switched i beleive

[showsii]

YES!

They must be switched then! Yes my Transformers are from Rj. Its all coming together now.

Thanks everyone!


Once again, this amp rocks.

Ian

[Cliff Schecht]

I've mixed this up before too. Instead of messing up my wiring on personal amps, I just relabel the selector switch with the correct correlation between setting and impedance.

[showsii]

I've mixed this up before too. Instead of messing up my wiring on personal amps, I just relabel the selector switch with the correct correlation between setting and impedance.

That sounds like a plan.


Ok, quick question. I happen to like 16ohm going into an 8ohm cab.. Now, is this going to screw up something? Tony, it seems by your post that you can mix and match ohms safely, that everyone has a preference. Is that what you are saying? (just double checking)

Thanks

Ian

[paulster]

I've mixed this up before too. Instead of messing up my wiring on personal amps, I just relabel the selector switch with the correct correlation between setting and impedance.

The only thing I don't like about this is how many times have you reached over the top of an amp to plug into a cab and rotated the impedance selector all the way to one end and then back enough clicks to know what impedance it's set on? In this case you'll have to remember that it doesn't go 4, 8, 16 in order.