making an 8 ohm amp into a 4 ohm one

[drew_half_empty]

ok so this kinda goes along with my other thread but i think this question merits its own thread

so the traynor yba-1 looks good, but it's 8 ohm, and seeing as i own a bassman, my 4x12 is 4 ohm

so what all do i need to do to make it a 4 ohm amp?

 

[That90'sGuy]

Re: making an 8 ohm amp into a 4 ohm one

You'd probably need new OT with a 4ohm secondary, unfortunately. Heyboer makes some good stuff.

+1. Unless by some great act of God there is a 4 ohm tap on the secondary (which I doubt because it'd probably be listed on the back of the head), you're going to need a new output transformer.

 

[the guy who invented fire]

Re: making an 8 ohm amp into a 4 ohm one

Short of putting a new tranny in your Traynor, I would opt for a Weber Z Matcher...it macthes mismatched impedencesm it's on his site.

 

[kevlar3000]

Re: making an 8 ohm amp into a 4 ohm one

I also have a Bassman and several Bassmasters. It is fine to run the Bassmasters into a 16 ohm load, those amps can handle that fine. You could wire a series/par switch into your cab so you could switch between a 4 an 16 ohm load. Very handy, as I recently did it when I got the Bassman. $3.00 at Radio Shack for the DPDT switch ( heavy duty) otherwise the Weber is a great option for ohm matching, just a little more spendy.

 

[drew_half_empty]

Re: making an 8 ohm amp into a 4 ohm one

what kind of OT should i go for?

a mercury magnetics one is out of my price range

also, would there be any way to wire in a tap? or would i need a new transformer for that too?

 

[drew_half_empty]

Re: making an 8 ohm amp into a 4 ohm one

http://www.informatik.uni-bremen.de/~dace/vb/models.html#bassmasteryba-1

ok now i'm confused, it's 8 ohm but can be run at 4?

 

[the guy who invented fire]

Re: making an 8 ohm amp into a 4 ohm one

what kind of OT should i go for?
a mercury magnetics one is out of my price range
also, would there be any way to wire in a tap? or would i need a new transformer for that too?

If you have an amp with only an 8 ohm tap, you can run it at 4 or 8 or 16 ohms with no issues assuming you have an amp with stout trannys...if you have an old Traynor you have an amp with stout trannys.

If you really want things to be matched up just get the Weber Z matcher...don't pull the tyranny out of the traynor, those are great trannys and the Z matcher will leave you amp completely stock and cost less than a new tranny anyway...

Just my 2 cents.

 

[Rich_T]

Re: making an 8 ohm amp into a 4 ohm one

If you have an amp with only an 8 ohm tap, you can run it at 4 or 8 or 16 ohms with no issues assuming you have an amp with stout trannys...if you have an old Traynor you have an amp with stout trannys.

If you really want things to be matched up just get the Weber Z matcher...don't pull the tyranny out of the traynor, those are great trannys and the Z matcher will leave you amp completely stock and cost less than a new tranny anyway...

Just my 2 cents.

Yeah, agreed. Another vote for leaving it stock and using a Z matcher.

 

[kjrocks]

Re: making an 8 ohm amp into a 4 ohm one

+1 on the Z matcher. Worked great for me and was easier than new speakers or a new tranny

 

[That90'sGuy]

Re: making an 8 ohm amp into a 4 ohm one

Wow... never even knew the Z Matcher existed, that's definitely the fool proof way to go!

 

[ES350]

Re: making an 8 ohm amp into a 4 ohm one

I have a early YSR that I run into 4 ohms....no problems.
There are very good OT's around for less than the cost of the MM's. The AES 50 watt Marshall OT comes to mind...

 

[LJ King]

Re: making an 8 ohm amp into a 4 ohm one

Tube amps are much more forgiving than most people will tell you.

Yes, matching output impedance with cab impedance will result in the greatest bandwidth/power transfer.

But remember, impedance is rated as "optimal", not an absolute. It will vary across frequency.

Just never run your tube amp without a load - no speaker connected. If it is a Fender, with a shorted speaker jacks your amp might survive. If it is a Marshall with open speaker jacks - your output transformer will be toast. Notice that Marshall stole the Fender schematics prior to Fender making piggy-back amps.

 

[Lewguitar]

Re: making an 8 ohm amp into a 4 ohm one

Drew, just plug your 4 ohm cab into the amp and if you like the way it sounds: you're done!

You won't hurt anything and you don't need to swap your tranny.

That might be a Hammond transformer...good stuff if it is!

Lew

 

[drew_half_empty]

Re: making an 8 ohm amp into a 4 ohm one

thanks guys