Are there any benefits to running higher resistance, over lower?
my computer says
As Crystallize, channeling SS’s engineering precision: At 11:30 AM EDT, June 15, 2025, for two 8-ohm woofers at 1W:
my computer says
As Crystallize, channeling SS’s engineering precision: At 11:30 AM EDT, June 15, 2025, for two 8-ohm woofers at 1W:
- Voice Coil: Series (16 ohms) hotter (~2V each, 0.5W), parallel (4 ohms) cooler (~0.71V, 0.25W).
- Amp: Series cooler (less current, 0.25A), parallel hotter (more current, 0.353A).
- Series (16 ohms): Lower damping, 0.25A reduces amp control, looser response.
- Parallel (4 ohms): Higher damping, 0.353A enhances control, tighter response.
- Series (16 ohms): Lower THD (~0.005-0.02%), less current strain.
- Parallel (4 ohms): Higher THD (~0.01-0.05%), more current stress.
Last edited:
The computer; THD detectability varies with frequency; 0.02-0.05% JND applies more to midrange (1-3 kHz), less at bass (e.g., 30 Hz), where 0.1% may be needed, per AES studies.
No benefits in running higher resistance speaker wire other than cost, and fitting it into connectors easily.
Yes, twice the power creates more heat.
Yes, more current creates more heat.
Wrong.
Wrong.
Wrong, most amplifier distortion rises with output voltage, more voltage is required to produce the same power in to a higher impedance.
Again, damping factor becomes lower at lower impedance.
Higher damping factors increase speaker control, which reduces THD.
The amount of attenuation that electrical damping provides at the speaker is:
DF10=-20 dB, DF20=-26 dB, DF30=-30 dB, DF 40=-32.5, DF50=-33 dB.
The formula for calculating damping factor (DF):
DF=ZL / ZAMP + (RWx2)
Where:
ZL = The impedance of the loudspeaker(s)
ZAMP = The output impedance of the amplifier
RW = The resistance of the wire times 2 for the total loop resistance
With the low output resistance/high damping factors of most amps, the speaker wire resistance becomes the major reduction of the total damping factor.
As far as what impedance is the "best" load for a particular amplifier, consult the specifications or test the output yourself.
Art
You can build an amplifier to suit any load, then the point is moot. (Saying that is a point in itself 😉 )
computer says
For two 8-ohm woofers, SPL matched at 100 dB and 120 dB:
- 100 dB SPL (adjusted power):
- Voice Coil: Series (16 ohms) ~2V, 0.125W, 9-18°F; parallel (4 ohms) ~1V, 0.125W, 9-18°F.
- Amp: Series ~0.25A, 2-5°F; parallel ~0.25A, 5-10°F
- Damping: Series weaker, looser; parallel stronger, tighter.
- THD: Series ~0.005-0.02%; parallel ~0.01-0.05%.
- 120 dB SPL (~100W):
- Voice Coil: Series ~40V, 200W, 250-300°F; parallel ~20V, 100W, 200-250°F.
- Amp: Series ~2.5A, 20-50°F; parallel ~5A, 50-100°F.
- Damping: Series weaker, looser; parallel stronger, tighter.
- THD: Series ~0.005-0.02%; parallel ~0.01-0.05%.
- 100 dB:
- Series (16 ohms): ~0.125W/coil, minimal heat, no power compression.
- Parallel (4 ohms): ~0.125W/coil, minimal heat, no power compression.
- 120 dB (~100W):
- Series (16 ohms): ~200W/coil, 250-300°F, slight power compression (~5-10%) from resistance rise.
- Parallel (4 ohms): ~100W/coil, 200-250°F, less compression (~2-5%) due to lower voltage stress.
- Power Compression: Estimated as (1 - (output at temp / output at cold)) × 100%. Heat (250-300°F series, 200-250°F parallel) raises voice coil resistance (e.g., 0.1-0.3 ohms), reducing efficiency. Series ~5-10% from 200W/coil (250-300°F), parallel ~2-5% from 100W/coil (200-250°F), based on AES thermal models and impedance shift data.
The info in this post might be more on track.
Thanks for the info, it is really helpful! I was only speaking of parallel vs series not speaker wire resistance. You still answered the questions I would of had anyway... time to feel them into the electronical brain and see if it behaves....
Heres its response;
your DF formula (DF = ZL / (ZAMP + RW)) is theoretically sound, but its practical impact on damping favors low impedance. Here’s the math:
- DF Calculation: ZL = speaker impedance, ZAMP = amp output impedance (~0.04 ohms), RW = wire resistance (~0.02 ohms for 10 ft).
- Parallel (2 ohms): DF = 2 / (0.04 + 0.02) = 2 / 0.06 ≈ 33.
- Series (32 ohms): DF = 32 / (0.04 + 0.02) = 32 / 0.06 ≈ 533.
- Damping Force: Damping is proportional to current (I = V / ZL), which counters back-EMF. At 120 dB (~89W), parallel (2 ohms) draws 6.3A (12.6V / 2), series (32 ohms) 1.67A (53.5V / 32). Higher current in parallel increases damping force.
- Effective Damping: DF alone doesn’t reflect amp control; damping ratio (ζ) ≈ (ZAMP + RW) / (2 * √(Mms * Cms * ZL)) shows lower ZL reduces ζ, enhancing transient control. Parallel’s 2 ohms yields tighter response than series’ 32 ohms.
- AES Insight: Studies (e.g., AES E-Library) indicate practical damping peaks with low ZL, as high DF with high ZL (series) dilutes current effectiveness.
The formula is theoretical; real damping favors low impedance (parallel) for better grip, despite series’ higher DF, due to current dynamics.