Bass Amp Transformer Dilema

[6bm8]

I have in an 014679 power transformer from a Fender Super Twin/Studio Bass and a vintage 1974 Ampeg 8950004 output transformer. I'm planning a simplified Studio Bass build, just Blackface Normal Channel -> LTPI -> Buffer -> 6x6L6. Should I use the oversized Ampeg iron I already have, or sell that and get a Hammond 1650T? If I got the 1650T, I'd go ahead and use the ultralinear taps just like the Super Twin/Studio Bass.

[thetragichero]

looks like the svt transformer will work (both 1k9 primary), but that Hammond will shave off 18lbs. looking at sold listings on reverb (there aren't many for svt output transformers) looks like it would be a wash moneywise, besides shipping (unless you can find somebody who blew the ot in their svt, in which case you might could make a couple bucks)

[Stevem]

The question needs to be asked as to what general usage will this amp be for, home recording and practice with a band, or gigging out with and if gigging out is the case with how many and what size drivers and then in terms of those drivers used what SPL level are they rated at?

When you use the UL taps on a OT you are running the tubes somewhere between the Pentode that they are and a Triode.
As such your getting a reduced wattage output, but a cleaner output signal.

On the other hand if you already have a excess level of clean RMS wattage ( like 135 watts in late 4 tube Fenders ) that your not tapping into when using the amp then not running a Non UL type OT will provide you with even more clean reserve wattage and save you the cost of buying a new UL tapped OT.

My Bass rig I have used for decades consists of a 120 watt SS head and two very efficient EVM 15" drivers in a tuned cab, and I have never needed any amp with more power even to keep up with a full 8-12" speaker Marshall or Highwatt stack!

Even to this day with the added power needs of the low B string on two of my Basses I have not needed more then the 120 watts I have been using, grated we don't play anywhere as loud on stage any more , but that's the story I can relate to you.

Also of note is that if you play or will some day use a 5 string Bass, 10" drivers of any number , brand and cost will not cut it period!!
You need atleast one 15" driver that can go down to 30 HZ with good efficiency.

[jabguit]

just Blackface Normal Channel -> LTPI -> Buffer -> 6x6L6.

Six 6L6s??

[thetragichero]

Also of note is that if you play or will some day use a 5 string Bass, 10" drivers of any number , brand and cost will not cut it period!!
You need atleast one 15" driver that can go down to 30 HZ with good efficiency.

not to start up controversy and with all due respect to usually quite informative postings, but this is 40+ year old incorrect thinking. there's a reason 10" speakers are the industry standard for bass guitar and it's because you can fit a while lot more of em (about 4) in the same area as a single 15" speaker while providing almost twice as much speaker surface area. if the 1x15 or 2x15 is a dinosaur (we'll consider anything with 18" speakers as cyanobacteria and won't even mention), the 4x10 is some sort of cro-magnon man as they've also fallen largely out of favor. with the advances in both driver and enclosure design over the past few decades, many folks are gigging with one or two 2xs (2x10, 2x12) or going di (pa wattage being ridiculously cheap compared to musical instrument amp wattage, it makes sense)
then there's the fact that 30hz (or anything remotely close) isn't musically useful and huge power hogs. many bassists are running high pass filters anywhere from the high 50s to the low 100hz in front of their amps because then they're only amplifying stuff that you'd want in a full band mix. there's a really cool phenomenon called "missing fundamental" where the thing between our ears "hears" those extremely low frequencies based on the distribution of the harmonics above it that we do hear. it's why some "dance"-type music that's produced with smartphone speakers in mind can sound so rich and bassy even though it's coming out of one crappy 1/4" speaker
frankly I'm glad that the days of folded horns, 2x18s, full stack guitar rigs are behind us. while visually impressive, they're a bear to break down at the end of a long night of playing

[6bm8]

This amp is for "home" use with normal 4 string bass. At my home means a full drum kit, baby grand piano, guitar, and my wife has some friends who play horns, so maybe after COVID we will have some trumpets and trombones over to jam too. This is going to be complete overkill, a 100 watt SS amp would cut the mustard. An SVT is way too much, a Bassman 100 would be fine. But I've already got some heavy iron, I've built a few guitar amps, and have never had a proper tube BASS amp. Weight is not an issue, even if I end up gigging I don't mind heavy gear.

I'm mostly wondering if it's a waste too much iron in the form of a vintage SVT OPT that maybe someone could put to better use. Maybe a bigger deal is that the SVT OPT is a laydown which means more chassis work, the Hammond being a standup, drill a couple holes in the right place and call it good.

Reasons I'd go ultralinear with the Hammond iron are: 1) closer to the Fender Studio Bass/Supertwin circuit, 2) very slightly less complex build.

Cab will be some good 1x15 or 4x10. If I can find an old Mesa Diesel 4x10 for cheap I'll get one, that's my favorite cab ever.