Say you have a biwire speaker with a low freq section with a 4ohm impedance, and mid/tweeter section 8ohms. You biwire it to a tube amplifier that has both a 4 and 8 ohm winding, connecting the speaker sections to the appropriate transformer output terminal.
What's the effect?
What's the effect?
Depends. If the speaker as such was advertised as '8 ohms' (or '4 ohms'), the xover filter would be dimensioned to take care of the difference in individual drivers.
Your proposed connection would then upset the response.
Jan
Your proposed connection would then upset the response.
Jan
Would such a biwire speaker even exist as a commercial product?
Maybe I don't understand the question as was intended but I read it as connecting an 8 Ohm and a 4 Ohm speaker to the 8 Ohm and 4 Ohm taps of one and the same output transformer. That would at least mess up the impedance ratio, and maybe even more. In many datasheets for toroidal output transformers there's a warning to not use more than one tap at a time.
Maybe I don't understand the question as was intended but I read it as connecting an 8 Ohm and a 4 Ohm speaker to the 8 Ohm and 4 Ohm taps of one and the same output transformer. That would at least mess up the impedance ratio, and maybe even more. In many datasheets for toroidal output transformers there's a warning to not use more than one tap at a time.
Agreed. Biwired speakers are normally meant to be connected to the same speaker connections on the amp.
The speaker would be advertised as 8 ohms or 4 ohms, whatever the internal drivers.
Sometimes you find a mix of 8 ohms and 4 ohms drivers inside a speaker, selected to combine to get a flat response or better power delivery or whatever.
Jan
The speaker would be advertised as 8 ohms or 4 ohms, whatever the internal drivers.
Sometimes you find a mix of 8 ohms and 4 ohms drivers inside a speaker, selected to combine to get a flat response or better power delivery or whatever.
Jan
The speakers, woofer pair 4ohm and tweeter/mid 8ohm are separately wired to input terminals with a nominal 6.5 ohm factory rating(I believe with jumpers).
You still want to put them on the same tap, usually 8 ohm (like my ProAcs which are nominally around 6.5 ohms, IIRC, but most people use an 8 ohm tap) or 4 ohm if you prefer, but use the same tap.
Thats how I have my speakers hooked up now using Hammond 1620's-
4 ohm taps (L&R) are hooked to 12" Dayton SD-315A's (8 ohm DVC in parallel)
8 ohm taps (L&R) are hooked to modded Polk T50's. Mod's include reducing cavity volume and raising low range Fco to let the dual 12's in separate vented enclosures do the heavy lifting. Used links below to decide on passive X over LC values. Listened and tweaked... bottom line is you should try it.
I asked same Q's you are asking here couple years ago.. referred to it as 'Bi-coiling"... Lots of theories, but no "Yeah I've tried that & it sucked w/ back to back listening". Online search didn't turn up much either. So decided to try it- what my ears told me was that the mid's and hi's were stronger and cleaner. Not sure if it helped down low- this is my reason why-
If you look at passive X over circuits, they most always have series coil & shunt cap on the woofer for low pass filter. This path attenuates the mids and tweets signals that are tied into this single source. If you have dedicated windings to drive each section, then passive crossover effects from one group of speakers don't affect the other group nearly as much. I say this cuz both output windings with differing impedances/freq load the secondaries differently, and therefore the primary differently.
Since you're setup provides the opportunity, you should try it. Get you ear close to each speaker group and listen... back to back...then decide
Jim
https://www.hammfg.com/electronics/transformers/classic/1608-1650?referer=790
https://www.erseaudio.com/CrossoverCalculators/Second-Order-3-Way
http://www.kbapps.com/audio/speakerdesign/calculators/ThreeWayCrossoverSchematicCalculator.php
The issue is that the speakers would have been designed to see equal AC voltage at the woofer and tweeter/mid terminals, with the mid and tweeter perhaps padded to achieve the correct balance. If you connect the tweeter/mid to the 8 ohm tap and the woofer to the 4 ohm tap, the tweeter/mid will now see a higher AC voltage and will be louder - "...the mid's and hi's were stronger and cleaner...". You may or may not like this, but it will be different to what the designer intended.
Tikiroo, I understand your points. I'm still curious with this "equalization" by padding down for correct balance why the speakers sound different connected to either the 8 or 4 ohm tap given that each section(woofer mid/tweeter) receives the same AC voltage(?).
If I understand your last post correctly, you're assuming that the 8 Ohm and 4 Ohm taps output the same voltage? This isn't correct, so maybe you mean something else?
If instead, you mean that your speaker has user-adjustable level controls for the mid/tweeter, and that you've attempted to equalize the comparison, then you've asked a more subtle question. Young humans can hear differences of maybe a dB or even less between adjustments across a broad spectrum like your example. This is a level of fine tuning that's very difficult to get by ear alone.
For the sake of music listening, we're amazingly forgiving of huge errors of frequency response in both magnitude and time. Good thing, because all loudspeakers + rooms are amazingly awful. By sheer internal computing power we forgive these flaws, and listen to music anyway. But we can hear smallish differences if we focus our attention there.
Attention is the only important thing. All good fortune,
Chris
If instead, you mean that your speaker has user-adjustable level controls for the mid/tweeter, and that you've attempted to equalize the comparison, then you've asked a more subtle question. Young humans can hear differences of maybe a dB or even less between adjustments across a broad spectrum like your example. This is a level of fine tuning that's very difficult to get by ear alone.
For the sake of music listening, we're amazingly forgiving of huge errors of frequency response in both magnitude and time. Good thing, because all loudspeakers + rooms are amazingly awful. By sheer internal computing power we forgive these flaws, and listen to music anyway. But we can hear smallish differences if we focus our attention there.
Attention is the only important thing. All good fortune,
Chris
The effect will be that:
- the 8 Ohm connected speaker will see more AC swing across it;
- the 4 Ohm connected speaker will see sqrt(2) times less AC swing than the previous, but same power;
- the tube amp will work on a loadline that is half the one has been designed to, so its performance will not be optimal, so most probably more distortion and possible damages to the amp can occur.
The "padding down" I mentioned was just the usual that might be included in the crossover to account for differences in driver sensitivities. The point was that presuming the levels are correct to begin with, by connecting the woofer and mid/tweeter sections to different taps you are feeding them with different voltages so the levels will no longer be "correct". The loadline issue bought up by zintolo is another matter. I don't know that the load will be half (it depends on the other crossover components) but it will certainly be different.