| morbo |
I know that 16 ohm speakers are meant to be wired together to form an 8ohm load, for instance in an MTM. But, it is safe/advisable to run a 16 ohm driver like this one:
http://www.creativesound.ca/details.php?model=WR125ST
From a regular amplifier or reciever? |
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| MEXXX |
You could run a 160 ohm driver on a "regular" amp and it wouldnt hurt it.
The higher the impedance, the lower the "draw" on the amp. So yes, you can. But remember, you will only get about half the power into a 16 ohm speaker as you would an 8 ohm. |
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| Timn8ter |
| Many owners of tube amps prefer a 16 ohm load. |
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| morbo |
| thanks guys, looks like I will be ordering these |
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| planet10 |
| quote: | Originally posted by MEXXX
But remember, you will only get about half the power into a 16 ohm speaker as you would an 8 ohm. |
And half the distorion (in general)
dave |
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| morbo |
| quote: | | And half the distorion (in general) |
Power shouldnt be a problem, this speaker will get the (claimed) 100wpc into 8 ohms from my mass market reciever. Your distrortion statement intrigues me though - my reciever (Pionerr 811s) has a pretty weak amp section, and does not 'officially support' a 4 ohm load, does this mean it will have an easier time driving a 16ohm speaker than an 8ohm speaker? Because with my big floorstanding 8ohm towers, it is not very dynamic, I ended up using the preamp outs for the front channels so I could use an outboard amp with some balls (1970's Yamaha reciever), and it would be nice to avoid the need for a separate amp for this speaker (center channel). |
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| Timn8ter |
| quote: | Originally posted by planet10
And half the distortion (in general)
dave |
That's been my experience too.
(need a new keyboard Dave?)
:D |
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| planet10 |
| quote: | Originally posted by Timn8ter
(need a new keyboard Dave?)
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No, just never learned to type (the f key is right beside the d key)... took Grade 11 Math instead of Grade 10 typing.
dave |
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| salas |
| Maybe you lose less than the theoretical 3dB with 16 Ohm series using small tube amps, especially SET? I would expect so with a high output impedance amp. Did you ever measure SPL when parallel (4 Ohm) double drivers vs series (16 Ohm) when fed off an 8 Ohm tap? Speakers are governed by voltage, so maybe less of a loss than expected? Do you subjectively feel not so much of an spl loss when using push push 16 Ohm vs push push 4 Ohm with tube amps? Planet 10? |
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| salas |
| Timn8ter? Planet10? voice in a desert here.... |
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| kelticwizard |
| quote: | Originally posted by salas
I would expect so with a high output impedance amp. Did you ever measure SPL when parallel (4 Ohm) double drivers vs series (16 Ohm) when fed off an 8 Ohm tap? |
Take an amp, solid state or otherwise, designed for an 8 ohm speaker.
Take 2 eight ohm speakers, each rated 90 dB at 1 watt, (2.8 volts for an 8 ohm speaker).
A single 8 ohm speaker, at 2.83 volts, will be playing at 90 dB. Add another speaker in parallel, and they will be playing at 96 dB. However, they will be drawing twice the current. Nevertheless, at any given voltage level, the parallel pair will be 6 dB louder than the single 8 ohm.
Now, take the same single 8 ohm speaker at 2.83 volts, playing at 90 dB. Add another identical speaker in series. the series pair will still be playing at 90 dB at 2.83 volts. However, they will, together, be drawing half the current of the single 8 ohm speaker, therefore, they will be running at half the power. But they will still put out the same SPL as the single 8 ohm at the same voltage level-in this case, 2.83 volts.
To summarize:
2.83 volts = 1 watt ONLY for an 8 ohm load.
A) (1) 8 ohm speaker at 2.83 volts = 1 watt drawn = 90 dB.
B) (2) 8 ohm speakers in parallel at 2.83 volts = 2 watts drawn = 96 dB.
C) (2) 8 ohm speakers in series at 2.83 volts = 1/2 watt drawn = 90 dB.
The extra 3 dB SPL for B and C comes from the fact that they have twice the cone area of A. |
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| Timn8ter |
| quote: | | Do you subjectively feel not so much of an spl loss when using push push 16 Ohm vs push push 4 Ohm with tube amps? |
I definitely notice a loss when wiring series vs. parallel on bipole applications. It does take a little more power to get the drivers going but the amp has a much easier time with control regardless of it being tubed or SS. Nelson Pass' First Watt article does a good job of explaining this. A pair of WR125ST wired in parallel should give you 88db/1W with excellent control, as they are designed to. I heard the WR125S pushed with a typical Japanese solid state receiver and it still sounded great. I'm going to get a pair (not the 16 ohm model) and try them out on my EL34 push-pull. I'm going have to make shelf space for XBL^2 based drivers now. :xeye: |
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| Brett |
| Good analysis KW, but doesn't it omit the finite output Z of the amp, which is quite often large in tube amps wrt the speakers Z, and assume that the amp has an output Z of 0R? |
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| salas |
kelticwizard
I was seeking practical driveability and subjective spl feel information over many FR types considering the output trafo limitations of lil tube amps despite the well known scalar and wattage addition math. Any experience with that? For instance I measured only 2dB loss from 16 Ohm series vs 4 Ohm on such an amp's 8 Ohm tap. Considering the higher impedance tube output stage loading derived, less distortion reported is well founded.
To put it simple. Is 16 ohm always subjectively preferable when with SETs and the like? |
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| planet10 |
| quote: | Originally posted by salas
Maybe you lose less than the theoretical 3dB with 16 Ohm series using small tube amps, especially SET? |
Yes, i would expect this is true... particularilly if you use the 16 ohm taps.
dave |
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| planet10 |
| quote: | Originally posted by kelticwizard
A single 8 ohm speaker, at 2.83 volts, will be playing at 90 dB. Add another speaker in parallel, and they will be playing at 96 dB. |
Good explanation Peter... but it rests on the above incorrect statement.
A 2nd driver in parallel, gives you 3 dB more (ie 93 dB) given the same 1 watt in...
the myth you have stated comes from many people assumming all amps double their power into half the impedance and therfore put out 2 W into the now 4 ohm load. In actuallity the amps that double (or even come close) into 4 ohms vrs 8 ohms are actually only a small subset of the set of amplifiers).
dave |
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| SY |
| p10, let me nuance that a bit. What you say is exactly correct when considering maximum power. But I think that most 20 watt amps, for example, would indeed double their power into 4 ohms versus 8 ohms at the 2 watt level. Not exactly, because source impedances aren't zero, but they're usually pretty small. |
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| kelticwizard |
| quote: | Originally posted by planet10
A 2nd driver in parallel, gives you 3 dB more (ie 93 dB) given the same 1 watt in... |
Yes, that is why I stated it as 2.83 volts in, and not "1 watt in".
| quote: | Originally posted by planet10
...the myth you have stated comes from many people assumming all amps double their power into half the impedance and therfore put out 2 W into the now 4 ohm load. In actuallity the amps that double (or even come close) into 4 ohms vrs 8 ohms are actually only a small subset of the set of amplifiers).
dave |
I gave the answer for small to intermediate power levels, and figured the absolute max level could wait for later in the discussion. |
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| kelticwizard |
| quote: | Originally posted by Brett
Good analysis KW, but doesn't it omit the finite output Z of the amp, which is quite often large in tube amps wrt the speakers Z, and assume that the amp has an output Z of 0R? |
You are absolutely correct, I did assume an output Z of zero, figuring, perhaps incorrectly, that while tube amps have higher output Zs than solid state, the output Z of a tube is low enough to make the analysis workable.
If in fact the output Z of a tube amp does make a real difference, my analysis goes out the window. |
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| salas |
| even 2 Ohm output Z isn't rare with SETs. |
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| kelticwizard |
Salas:
My apologies. It was 8 o'clock on Sunday morning over here, and the fellows you were patiently waiting for an answer from were on the West Coast, three hours behind me. It seemed like you were asking for basic information, so I gave it. Fact is, I do not have a lot of experience with tube amps or even transformer output amps, so I just made the assumption that the output Z was low enough to not to take into account.
If the output Z is high enough to make a difference, then the information I gave you is wrong.
I would only suggest that if indeed your output Z is high enough to make the difference, then if you plan to use an enclosure for your speaker, it would be wise to measure the speaker Qts yourself using that self-same amp. A high output impedance of an amp will change the speaker's Qts value, and therefore it's performance in an enclosure-or even outside an enclosure.
http://sound.westhost.com/tsp.htm |
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| salas |
| Thanks KW. I always go underdamped with 'tube in mind' speakers. You have a strong point here, that I havent seen it discussed much, though it can make or brake a good tube friendly speaker. |
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| planet10 |
| quote: | Originally posted by SY
But I think that most 20 watt amps, for example, would indeed double their power into 4 ohms versus 8 ohms at the 2 watt level. |
Even my tube amp... or an OTL (more likely to put out 1/2 as much power into 1/2 the load)
What bothers me is that people seem unwilling to separate the speaker reality -- 3 dB more -- from a possible amplifier reality.
Even if you series 2 8 ohm drivers you get 3 dB more with the same power input. Using voltage input is, IMHO, a marketing ploy.
dave |
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| johninCR |
| My Decware SET amp prefers a 2 ohm load and has more power there. What I need is a good 2 ohm high efficiency full range driver. Does anyone know of one? These 8 ohm speakers are killing me when I have the house to myself. |
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| kelticwizard |
There seems to be a trend in car audio toward 2 ohm drivers, or at least dual voice coil 4 ohm drivrs. Most of the drivers seem to be woofers, though there are some mids.
Image dynamics makes a few 2 ohm bass mids, but I cannot find any info on frequency response, etc.
Good luck.
http://www.full-line-audio.com/image_dynamics/mid-bass/ |
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