# Traynor YBA-3 Custom Special OT impedance?



## JC103 (Oct 6, 2007)

I have a pair of these beasts dating from 1969 according to the filter cap dates. This is the version of the circuit with the choke transformer. The power and output transformers are absolutely huge!! God bless Pete Traynor for overbuilding these amps, they are truly bulletproof. I am pretty sure that I will not run into any problems here, but I am looking for opinions on how "safe" it is to run speaker cabs that are either 4 or 16 ohms on the 8 ohm OT? I have had the OT measured and it is indeed 8 ohms. However no one on the internet can agree if it is safe to run cabs rated one step beyond the 8 ohm rating in either direction. Some say only use a 16 ohm cab, others say nope, only 4 ohms is safe. Traynor even tells people 4 ohms is safe if you email them. 

Bass players on talkbass.com have been running them into 4 ohm cabs for 20+ years and they are still kicking. I am aware that the speaker jacks on these were originally wired in series. I have one cab that is 8 ohms, so no problem there, but the other is currently wired for 16 ohms. The amp on the left sounds and perform fine when run with the 16 ohm cab. There is way more volume on tap than I'll ever need, I hardly ever get over 2.5 on volume knob. Considering these can put out 180w on a scope at full volume, I think I'm safe running them at conservative levels. Are there any Traynor experts out there that can offer some clarity to the situation?

FYI: I run these amps in stereo, so one cab per amp.

Speakers in the left cab are Eminence Lynch Super V12's wired in series for 16 ohms (300w).
Speakers in the right cab are Eminence Reeves OEM Vintage Purples wired in parallel for 8 ohms (150w).


----------



## High/Deaf (Aug 19, 2009)

In my experience, a mismatch of 2 either way isn't an issue. Mismatches are only a problem if you are at or near the rated output. Well below that should be OK. And considering the overbuilt nature of Traynors of that era (Pete took pride in making them strong like bull), that is an extra level of protection.

I played my Night Train 15W head at a 4X mismatch for about 45 minutes. It was in a big rehearsal studio, with drums and a big PA. The 412 was marked as 16 ohms but was actually 4. I used the 16 ohm output from the head and played (near full up) until it was so hot I had to stop (couldn't touch the steel cage, let alone the transformer). I recognized the problem, let the amp cool down, used the 8 ohm output and finished the night. The power tubes took a shit-kicking but the amp itself was no worse for the wear. Now this is an Asian-built PCB amp, with big (but not Trayor big) transformers. I think we consider tube amps as fragile. Some of the newer ones perhaps are (saving cost, weight and size on just-big-enough transformers) but the old amps, like yours, were 'brute strength and stupidity'. Tubes are not as good these days, but they are easily replaceable. The amp itself, unless you are playing really, really loud, probably won't even blink at a X2 mismateh. Just keep and eye (or finger) or the transformer temps.

This is my opinion. I'm sure you will get others. Caution is certainly not a bad idea - go a little at a time and keep an eye on overheating. I think your ears will give up before the amp will.


----------



## cboutilier (Jan 12, 2016)

I ran my 2 ohm Super Reverb on a 2 ohm cab for 4 hours straight last night with no issues. Only turned it up to two though.


----------



## flyswatter (Apr 6, 2016)

The general rule for tube amps is that higher than rated impedence is fine (so, 16ohms on a 8ohm transformer is okay) but you lose some of the efficiency of the amp output. I often run my Traynor YBA-1 on a 16-ohm Celestion cab just because I like the sound of that cab and have never had a problem, even on 3-4 hour gigs. 

Lower impedence (4ohm load on a 8ohm transformer) can overheat the transformer and, theoretically, blow it -- although as someone said above the "big iron" amps like Fenders, Traynors and Marshalls can withstand the mismatch. The only time I've witnessed a transformer about to blow, was in a Super Champ (much small transformer, etc) where there was a zero ohm load on the speaker owing to a shorted output jack. I have a friend who blew the tranny in his Eden solid state bass head when he forgot to plug in the speaker. But amps like that are built nothing like the old Traynors in terms of durability.


----------



## WCGill (Mar 27, 2009)

High/Deaf has it-2x is not a big deal. However if the mismatch is bigger, LOWER is safer. A higher ohm mismatch could be problematic due to flyback voltages in the OPT. Older Fender amps always had a shorting output jack on the main speaker out so that if you forgot to plug in a speaker there would be no damage as the load would be zero. An infinite load is a different story.


----------



## High/Deaf (Aug 19, 2009)

flyswatter said:


> The general rule for tube amps is that higher than rated impedence is fine (so, 16ohms on a 8ohm transformer is okay) but you lose some of the efficiency of the amp output. I often run my Traynor YBA-1 on a 16-ohm Celestion cab just because I like the sound of that cab and have never had a problem, even on 3-4 hour gigs.


Not 100% true. Too high of an output load can cause excessive flyback voltage (reactive) that can, in theory, break down or arc across winds in an output transformer. I've never seen it happen, but I wouldn't go much beyond a 2X mismatch, especially if running the amp hard.



> Lower impedence (4ohm load on a 8ohm transformer) can overheat the transformer and, theoretically, blow it -- although as someone said above the "big iron" amps like Fenders, Traynors and Marshalls can withstand the mismatch. The only time I've witnessed a transformer about to blow, was in a Super Champ (much small transformer, etc) where there was a zero ohm load on the speaker owing to a shorted output jack. *I have a friend who blew the tranny in his Eden solid state bass head when he forgot to plug in the speaker. *But amps like that are built nothing like the old Traynors in terms of durability.


???

SS amps only have a power transformer, and SS amps can be run open-circuit (no load, no speaker, whatever) all day long with no problems (too low of a load impedance will hurt them though). If he blew his PT, it was unrelated to forgetting to plug a speaker in.


----------



## JC103 (Oct 6, 2007)

Thanks for all the replies. I have played the 16ohm cab with both amps now and have found that after an hour of run time the OT is still cool to touch. After three hours it warms up a fair bit, but no where near hot enough to cause any concern. I think I will just continue on enjoying the great tones I am getting from these amps.


----------

