Ultra Linear OT in a guitar amp?

[Loomer]

Looking at transformer options I've chanced upon some OTs labelled as "for HiFi" which come with the UL taps.

My understanding is that using those will work the power tubes in a more triode-like way, as well as increasing headroom and flattening the frequency response.

More to the point though, would these transformers be fine to use without bothering to wire up the UL taps or would they still tend to behave differently compared to another OT of similar specs? And were they to be perfectly usable options, would the option of using those UL taps be there to be hooked up to a switch in the same manner some designs (eg Vox HW) have a pentode/triode switch?

Thank you in advance!

[shooter]

I stumbled onto a few Marshalls that used them, with the G2's wired to the OT for UL, I tried it, I liked it, will You?, try n see.
i wouldn't do any UL tap switching

[tdvt]

The late 70's big Fenders were UL & are looked down on, not sure that is is a deserved reputation or not.

I was rebuilding a 79 UL Pro earlier in the year, sounded nice to me (ongoing project with board conductance issues).  Actually have another copy of the same amp (in pieces) coming next week, as they seemed to be unloved.

The output ratings were wildly different between the non-UL & UL versions, 40W vs. 75-80W but I suspect much of that was on paper.

[sluckey]

All the old Sunn amps used UL "hifi" OTs. Sound very good to me.

[kagliostro]

When I started to read forums about guitar amps, 16 years ago, the most people were talking not in a very good way about guitar amps with UL OT, but this thing changed and there are many people that say they are satisfied by this architecture

Here on the forum there are guys that builded amps with such a feature and are happy with it

Franco

[bmccowan]

The late 70's big Fenders were UL & are looked down on, not sure that is is a deserved reputation or not.

About 20 years ago I bought 135W UL Twin Reverb. It was cheap and needed filter caps. Loads of clean power. A keyboard playing friend loved it and has it now on "loan." Loan is in quotes because I know I will never see it again.
I understand pedal steel players like that amp.

[tdvt]

About 20 years ago I bought 135W UL Twin Reverb. It was cheap and needed filter caps. Loads of clean power. A keyboard playing friend loved it and has it now on "loan." Loan is in quotes because I know I will never see it again.
I understand pedal steel players like that amp.

Since it's "loaned out", at least you don't have to move it!  My Pro is a bit of a beast, the Twin must be that much more...


I have heard the same about steel players liking them.

[PRR]

Yes, you can ignore (tape off) the UL taps and treat it as "normal".

[kagliostro]

Also a switch is possible

Franco

[Loomer]

Yes, you can ignore (tape off) the UL taps and treat it as "normal".

In fairness my curiosity was mostly in regards to that - obviously every OT will have its own characteristics and sound, but rating and impedance being the same I could consider one of those UL OTs as an option for guitar amp builds, or do they tend to have anything about them different to what we'd get in, say an Hammond 1750?

[PRR]

A UL winding "should" be "too good" for guitar. The primary wound in multiple sections to extend high frequency response on dummy load. The UL is just a little butter (and patent money) on a very good winding.

OTOH, I have seen a "plain" Ampeg OT with supersonic response. Also a single (or array) driver has a rising treble impedance which complements the rising reactive loss in a plain winding. Also just because an OT was wound UL does not mean it is "good" UL.

I don't know any reason (except nominal price) that you shouldn't just try it. The UL costs a buck more for leads, several bucks more for suitable core-size and winding frills, but that's when you order a crate. Buying onesies from odd-lots the price is arbitrary.