Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 12AX7 on January 13, 2017, 09:31:22 pm
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...is there any difference? In other words, say i have the exact same model in both 8 and 16 ohms and my amp has 8 and 16 ohm taps and i use the proper tapn for whichever i'm using. Would i hear any difference between them? I know it's an old question but I've never really heard a solid answer, so maybe it's just too subtle for most to hear? Anyways, what are your thoughts on the subject ? I'm thinking of trying several used speakers and don't always have the option of 8 ohms as my current one is so i want to be sure what i hear is the different model, not due partially to the different ohm rating.
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Some speakers are the same except 1.414/0.707 wire gauge/length, so unless you have other troubles, they work the "same".
Exact 1.414 gauge/length ratios are not real natural. Wire does not come in part-gauges (unless you mill your own as JBL used to), and a voice coil has to be whole layers, and often preferably 2 or 4 layers. All within tight limits of magnet gap structure and assembly clearance. There's always a big fudge between ideal size and what can really be wound. I have seen some which were not even close. They don't always tell you. And the D130 dips to 8 ohms but is so efficient it works near 16 ohms over most of the range, and I believe "8" or "16" were the same winding.
Output transformers have similar gauge and layer constraints, though not so tight. This probably does not affect you, but some 4-8-16 windings will show small differences at the different taps. This became critical in the Williamson _high_-NFB hi-fi amp, and a proper Williamson has a dozen secondary windings you connect series/parallel to get your desired impedance.
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.... but some 4-8-16 windings will show small differences at the different taps.
Yes, is it exactly as PRR say, I verified that on more than one OT
and if you put some interest on building your own OT you can understand why that happen
Franco
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Can anyone tell me what the tonal difference MIGHT be? I have a guy asking me if i'll be by today to look at a 16 ohm but i have yet to reply to him. it a 16 ohm likely to sound harder/brighter or softer/darker/
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To me it depends on the kind of mismach there is on the 8ohm tap and 16ohm tap
they can be slightly higher or lower respect the nominal impedance
But wait for the answer of someone that is more skilled than I'm
Franco
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MIGHT be. Could you go check it out and report back?
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Can anyone tell me what the tonal difference MIGHT be? ... it a 16 ohm likely to sound harder/brighter or softer/darker/
I'd expect a 16Ω speaker connected to the 16Ω tap of an amp to sound essentially-same as an 8Ω model of that speaker on the 8Ω tap of the same amp.
I was hoping Johan Segeborn (http://www.youtube.com/user/JohanSegeborn/featured) might have already recorded a video testing that theory, but maybe no such luck...
I was also surprised to see that Weber speakers didn't have an answer to this on their site (https://www.tedweber.com/lets-talk-speakers/) (they cover most every other common, and some uncommon, questions). Either that should tell us something, or you should click their link and ask the question for them to post!
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Heard the rumor, but never heard a difference. I have a cab wired where you can use it either 4 or 16 ohm or 8 in stereo. Multitap JCM 800 head. Used for recording many times as it contains Altec 417 8ohm speakers. 62 Pine Fender Cab with closed back and center board.
I have never heard any difference and have never really considered that I would. I guess electrically, looking at speaker graphs you see slight differences, but I do not hink they are audible.