Wes, absolutely! :-)
The Aerials use a 10" woofer, and that damn port. The midbass has a 15" driver and the bass uses an 18" driver.
I understand that field coil works the best down on the low side. Some say it is the best bass possible. I haven't been fortunate to hear this yet, but I've heard that it is fast, dynamic, and detailed. And way above my paycheck. :-) |
Would be nice if the poster new what hi eff means and its not 91db or 94db designs. So the threads title is wrong poster has not heard bass problems in Hi eff just a improper system match with a moderately efficient design. So to me the whole premise of this thread is wrong. |
Dan ed, perhaps I'm mistaken, but I was under the impression that field coil drivers usually have power limitations. I would guess that could be a problem with bass drivers. |
JohnK, I don't know of an absolute criterion for "hi eff". FWIW, IMHO, 94 dB is starting to get into the fold. |
Unsound, just FWIW, field coil technology in and of itself has no power limitations any more than regular magnetic systems.
Of course, most of the FC drivers we have seen so far are designed for high efficiency applications, and so do not handle all that much power. The midrange drivers in my speakers are FC and are rated at 50 watts. I would not want to be anywhere near them with that kind of power going through them- they are about 109 db 1 watt/1 meter. |
Hi Ralph,
Its been some years since I've looked at field coils. How did they solve the huge dc resistance numbers?
Tim |
Yeah, who gives a crap about big power when your pulling yourself out of the back wall with 1 watt. ;-) Seriously, I do prefer more power on the low end, 10-20+ on the mid bass and the big honkers are feed with a 500 watt QVC pro amp. I believe in headroom.
Actually, John does have a point. 98dB is what I think of as hi-eff territory. |
I would think field coil technology would enable higher sensitivity designs by nature due to stronger magnetic fields being made possible than with natural magnetic materials.
I've assumed that the potential for greater magnitude magnetic fields (and hence potentially greater sensitivity in accordance) is the prime benefit of FC technology and why I personally would covet such an approach for its game changing potential ?
Still waiting for the first field coil walsh driver to make it to market.
John Strohbeen, are you listening? I suspect the OHM CLS 2 way Walsh driver approach would lend itself best to pushing the limits using a field coil approach.
DDD drivers might benefit as well but tend to do less of the bass s perhaps less beneficial there.
Full range Walsh drivers can be destroyed relatively easily still using conventional magnetic fields, so perhaps less value there. |
|
Hi Unsound,
Its all perception my friend.
I think of low as 82 to 86
mid as 87 to 91
mid-high as 92 to 94
high as 95 +
Thats just me, I can see others not considering a mid high, but in the past, I've been aske say about 93db in sensitivity, is this normal or high. I've always said
"Well, its really mid to high"
Or is 87 really mid-low? Who really knows. |
Tim, I suppose that's about as good an answer as I could reasonably expect. |
Atmasphere, 50 Watts is not very high, but, if they are indeed 109 dB watt/1 meter your point is well taken. That is, if that's the free standing sensitivity. |
Apparently in reply to my post above, Timlub wrote: "Extension, dampning and efficiency are the tradeoffs. The vectors go in different directions. The op questions grip vs eff. The extension is not. as I understand. part of the query. But I'm all in for a free lunch of any kind. Elucidate."
Sorry for the late resopnse; I didn't check back in on this thread until just now.
First let me say that high damping is not necessarily desirable in and of itself; it is the in-room frequency response that we want to optimize because that is what correlates best with subjective preference. An overdamped speaker sounds... overdamped.
Suppose we have a fairly low-Q woofer in a considerably larger-then-optimum vented box. Let's say we're tuning to the upper 30's, giving us a -3 dB point in the upper 30's with a steep rolloff below that. With typical room gain, we're getting down to the mid 30's.
Now let's drive this same speaker with a low-damping-factor tube amp, but without changeing the tuning frequency. Boom! Quite literally - we now have a broad 2 dB hump across the middle of the bass region, and we've managed to push the -3 dB point south a little bit. So far this isn't a net improvement, but we're not done yet...
Let's drop the tuning frequency to the upper 20's, which elminates any peaking and gives us extension into the lower 30's before room gain. We're on the right track.
Now let's factor in room gain, and push the tuning down into the mid 20's. We get a nice gentle rolloff across the bass region that is approximately the inverse of room gain, and real-world extension into the upper 20's. In contrast, before our low-damping-factor amp came into play, we could have expected extension to the mid 30's after room gain.
This isn't hypothetical. I manufacture this speaker, and chose my woofer and box size and port system with all of this in mind. The scenario I've described doesn't necessarily play out with all high-efficiency speakers.
Duke |
Hi Duke,
Not overly important, but your last post was responding to Lewhite.
Tim |
Hi Duke,
Well after you got my attention by putting my handle in your post, I read your post thoroughly. I see your point completely and can see this happening, but won't that same speaker create frequency dips in some rooms? and/or do you recommend this speaker for certain types of rooms or placement? |
You're absolutely right Timlub - my bad! It was indeed Lewhite I was responding to! Thus dissolves my illusion of infallibility...
Okay to answer the questions which I think actually did come from you this time, the subject of room interaction dips (and peaks) is almost a different topic from the one I addressed. One could argue that a speaker which goes deeper is likely to have more peaks and dips simply because its wider bandwidth gives the room more opportunity to screw things up. But beyond that, I don't see any reason why a low-tuned box with a low-damping-factor amp would result in a room-interaction dip. If you're talking about a sag in the bass response above the tuning frequency, actually that's more likely to happen using a conventional amplifier with a low-Q woofer that's in a somewhat oversized vented box. If you have a modelling program, the effect of low damping factor is to raise the apparent Qes of the speaker (without correspondingly lowering its efficiency... hence, a "free lunch").
Oversimplifying a bit, you can get bass boost from boundary reinforcement or from a low output impedance amplifier. The two can work in your favor, or work against you... but if you can adjust the tuning frequency of the box, that can help a great deal.
Now since you brought up the topic of dips, I'll bring up the topic of peaks, so now we're talking about peaks and dips, which arise from speaker/room interaction. They are inevitable. My preferred technique for addressing them is to use four small subwoofers scattered asymmetrically around the room. This way each will produce a different peak-and-dip pattern at any location in the room, because each is a different distance from each of the room boundaries (in the horizontal plane anyway), and the sum of these multiple dissimilar peak-and-dip patterns ends up being pretty darn smooth. Now if we're talking about two speakers and no subs, one way to introduce some of this staggering/smoothing effect is to place the port on the rear of the speaker, at a different height than the woofer. Toe this speaker in fairly aggressively, and the woofer and port are each a different distance from the room boundaries in all three dimensions! Of course the port is fairly close to the wall in this scenario so it's getting a lot of boundary reinforcement, but that's been taken into account in the design stage (and/or the port's tuning frequency is user-adjustable).
In my experience paying all this extra attention to room interaction makes more of a difference in small rooms than it does in large ones.
Since I've been referring to free lunches here and there, let me mention one more that comes along with low damping factor tube amps (like those atmasphere makes): Their characteristics help to partially counteract thermal compression. Thermal compression arises when the voice coil heats up, and when that happens its resistance rises. Taking an extreme example here, at high power levels your 8-ohm woofer may become, in effect, a 10-ohm woofer. Not only does it take more power to push your woofer, but a high-damping-factor (constant voltage) amplifier will actually put out less wattage into that increased impedance, making a bad situation even worse. On the other hand a low-damping-factor amplifier will put out the same or perhaps even somewhat increased wattage into the higher impedance! So if you plan on pushing your speakers hard, and you hate dynamic compression, you might look for speakers that work well with that type of amplifier. Not that this is the biggest of free lunches out there, but it's at least on the menu.
Imho, and as we all now know, I'm hardly infallible...
Duke |
Hi Duke,
This all makes sense, back in my old days at SpeakerCraft/Marcof, we made a line speakers called Rock Boxes, We didn't call it thermal compression, but we did talk a fair amount about voice coil temperature rising and increased resistance. So in short, my guess seemed correct that you teach how to use your speakers to get the most out of room interaction with their placement. In my current speakers, an mtm, they are mirror imaged. I rear ported the ports in at an angle for the sole purpose of experimenting with how the speakers would react to room interaction. It clearly makes a difference. Not a world different from making a low qtc in a sealed box design to properly interact with a room. Obviously alot tougher with a ported box, but I love the variable port idea.
Thanks for your thoughts and good listening, Tim |
Duke, some of us are not so enamored with the sound of most loudspeakers with ported bass. |
Wes, absolutely! :-)
The Aerials use a 10" woofer, and that damn port. The midbass has a 15" driver and the bass uses an 18" driver.
I understand that field coil works the best down on the low side. Some say it is the best bass possible. I haven't been fortunate to hear this yet, but I've heard that it is fast, dynamic, and detailed. And way above my paycheck. :-)Dan_ed
Dan,
Precisely what i had suggested , multiple drivers is the way to go IMO, i have no doubt in what you have described, have fun ...
regards,
|
01-27-11:
Hi Unsound,
Its all perception my friend.
I think of low as 82 to 86
mid as 87 to 91
mid-high as 92 to 94
high as 95 + -Timlub
I would be in agreement here and efficiency mean different things to different topologies, a linesource for eg, 88 db would be very efficient IMO with a linesource after factoring the typical 9-12ft listening distance . |
Duke , it does seem to me that you are discussing speakers designed for corner placement, if not how would this apply when speakers are setup and voiced away from the walls.
regards, |
Wesixas, we may be splitting hairs here, but, I agree even more with your criterion. Of course the impedance will have to be figured in as well. |
"Duke, some of us are not so enamored with the sound of most loudspeakers with ported bass." - Unsound
Me neither! But remember that unless you're outdoors you never hear the bass independent of the room. The bass of most ported-box speakers isn't voiced to synergize well with gain from boundary reinforcement. However if done right, I believe that a good ported box has qualitative advantages over a good sealed box... mainly because it can be more closely tailored to what's going on in the room.
"Duke , it does seem to me that you are discussing speakers designed for corner placement, if not how would this apply when speakers are setup and voiced away from the walls." - Weseixas
Corner placement would be the extreme example, but wouldn't it make sense to approximately match the speaker's inherent bass rolloff characteristics with its acoustic environment regardless of where it is? If the speaker is up on a stand out in the room away from walls, maybe even in an open-floorplan home, then you're going to need a great deal more bass energy from the speaker in order to get acceptable tonal balance. In this scenario we'd shorten the ports and raise the tuning frequency, and once again a ported box gives us options that a sealed box does not.
I don't know why more manufacturers don't incorporate user-adjustable ports. Most of my customers have ended up happiest with a tuning frequency different from the one I shipped the speakers with. One customer is even tuning the two speakers differently based on where they're located (one's in a corner, the other isn't). I use Precision Ports, available from Parts Express and Madisound and probably others, in case anyone wants to retrofit them to their speakers. They screw into the cabinet so they can be removed, and I just use a few wraps of electrical tape to secure the sections together.
Duke |
Duke,
I think your assessment of the pros and cons of ports is right on! |
"Duke , it does seem to me that you are discussing speakers designed for corner placement, if not how would this apply when speakers are setup and voiced away from the walls." - Weseixas As mentioned by Duke, the speakers can be placed just about anywhere in the room, including corners. I own a set of his Jazz Modules and I too have to wonder why other manufacturers whose speakers incorporate ports don't allow for user adjustment. My speakers are 5' out into the room (19 x 15), 6' from side walls, and toed in approximately 45 degrees (the axis crosses about 18" in front of me). The bass port can be extended about 8", but I do not use any of the extensions. So I'm getting more bass energy over most of the bass region, but a more rapid roll off once it starts rolling off. With a 12 watt SET amp using it's 3 ohm tap (the speakers are 8 ohm minimum, 12 ohm top) I'm not suffering from lack of bass response. |
What I've been talking about above might be called "room gain complementary tuning". Let's look at a couple of well-documented examples. First up, the little Guru QM10, which defies expectations with its bass extension into the lower 30's. When placed up against the wall as recommended, the QM10 gets boundary reinforcement off the wall probably up to 200 Hz or so. As we go progressively lower in frequency, other room surfaces start to become a small enough fraction of a wavelength distant that their reflections are also in-phase, thus reinforcing the original sound. First the floor, then the ceiling, and somewhere along the way the near sidewall, and then the far sidewall. The designers apparently anticipated that this room gain would be about 3 dB per octave, and so they chose a woofer, box size, and tuning frequency that would give an approximately 3 dB per octave anechoic rolloff down to about 35 Hz. The rolloff accelerates after that, and after anticipated room gain we're -3 dB in the lower 30's. Here are SoundStage's measurements of the Guru QM10. Notice that from about 140 Hz down to about 35 Hz (two octaves), the bass rolls off at about 3 dB per octave anechoic: Guru QM10 measurementsIf anyone has a modelling program, I challenge you to find a practical sealed box alignment that will result in a 3 dB per octave rolloff anechoic like that. A Qts = .50 sealed box still rolls off at 6 dB per octave anechoic. The Guru is not alone in using a 3 dB per octave rolloff to take advantage of room gain. Let's look at the corner-placement-recommended Audio Note AN-E reviewed by Stereophile. From 200 Hz down to 25 Hz, the rolloff averages about 3 dB per octave: Audio Note AN-E measurements My point being, here are successful real-world examples of room-gain-complimentary tuning, including the all-important measurements that reveal what the designer is trying to do. If we were designing a speaker that would normally be getting less boundary reinforcement, we'd want to take that into account as well. Now wait just a minute, you're probably thinking; all this theory is great, but sealed boxes sound just plain have more natural-sounding bass than vented boxes! Okay, here's why (imho of course): Most sealed boxes roll off somewhere between 6 dB per octave and 12 dB per octave. Most (nearly all) vented boxes are tuned for deepest-loudest-possible bass, so they are "flat" as low as possible and then roll off very rapidly (18 to 24 dB per octave). Of the two, the sealed box's rolloff characteristics come closer to approximating the inverse of room gain, especially if it's a low-Q box, so sealed boxes will work better in a wider variety of rooms than "typical" vented boxes. And too much bass (more likely from a typical vented box) is a more heinous crime than too little bass. But take both speakers outdoors, where boundary reinforcement is negligible, and the flat-tuned vented box will have better tonal balance than our sealed box, and much better than our room-gain-complementary tuned Guru or Audio Note. It's not just the speaker and it's not just the room (or where it is in the room) - it's both. Duke dealer/manufacturer/no affilication with Guru Pro Audio or Audio Note |
Isn't Bose doing the same thing with his 901, he uses the walls to great effect.
regards, |
Duke, as you say "...but sealed boxes sound just plain have more natural-sounding bass than vented boxes!" Now I'm guessing (and really ALL this is just guessing on my part,) this is because after the bass driver emits, the vent lags after driver, then the room lags after the driver, then the room lags after the vent. That's a lot lagging. Then of course, unless your using separate subs, the loudspeakers when placed near the walls will have early reflections from midrange on up, smearing that all important range. Now if you do have separate subs, in order to keep any semblance of time coherence your going to have to introduce some sort of time manipulation. Since your already going to have to manipulate the signal, you might as well just consider bass eq from the full range loudspeakers out from the walls in the first place. Which should have the added benefit of better driver integration and more free floor space. |
Personally and absolutely speaking, I have never heard a sealed enclosure sound better than vented, now if you are running tube gear then there is some advantage in using a sealed enclosure. |
Unsound, I don't think the ear can hear all of these lags in the bass region.
That's one of the reasons bass is perceived as omnidirectional inside a room: Our time-domain resolution is so poor down there that the ear/brain system cannot tell the difference between the first-arrival sound and the reflections.
In contrast (so I've been told by a psychoacoustics researcher; never tried this myself), outdoors the ear is able to discern the direction of low frequency energy down to a much lower frequency than in a room. This is because there are no reflections to confuse the ear-brain system by arriving before it has resolved the initial impulse. We can hear direction at very low frequencies, as long as it's not masked by reflections arriving before our ear/brain system can isolate the first-arrival sound. All of those lags you mention arrive before the ear/brain can isolate the first arrival sound, so perceptually they just get blended in with it. And the room's effects on the frequency response are what dominates the perceptual modification of what would otherwise have been a clean first-arrival impulse.
I used to believe that the superior time-domain performance of a good sealed system was the reason for its "tight, natural" sound, but after reading Earl Geddes and Floyd Toole on the subject, I now believe that the in-room frequency response is the dominant factor by far.
Come to think of it, for many years the most natural-sounding bass I'd ever heard was from an IMF transmission line. A transmission line would inherently have poor time-domain behavior but might well have not only a room-gain-complementary native frequency response, but also significant physical displacement of its two bass sources (woofer and line terminus), with ensuing dissimilar room-mode-interaction from the two along with its smoothing effect. This would have addressed the two main problems of in-room bass reproduction: Gain from boundary reinforcement, and peaks-and-dips imposed by room modes (actually just different manifestations of the same problem). But no one really thought in those terms back then.
Duke |
Duke, we have all read that bass is omni-directional, and yet very often it's very easy hear where the sub-woofer is (perhaps it's because the overtones appear to come elsewhere?). Despite the theories, some of us clearly prefer the sound of sealed boxes over ported ones. As the old cliche' goes; "the proof of the pudding is in the eating". |
Stereophile recently claimed they had tested 750 speakers and the average sensitivity was 86dB . John Atkinson didn't come right out and say it, but seemed to prefer sealed box designs .
The only sub Iv'e heard that didn't give away it's position was a very large REL .
All this ( proof is the pudding ) talk is making me hungry . |
Duke,
Bass localization is detectable indoors, get the math wrong and you will know, phase is absolutely critical.
regards, |
Duke, "Come to think of it, for many years the most natural-sounding bass I'd ever heard was from an IMF transmission line."
So many folks who have been fortunate enough to be around Bud Fried's various designs echo the same thing. The corollary is that so few say it about most other true TL designs. Bud was intelligent/courageous/confident enough in himself to do things differently than everyone else without giving it a second thought; TL implementation being a prime example.
The last true example of the speaker Duke referenced was the Fried Studio V. So often, I say to myself exactly what Duke said. Though I've been around countless loudspeakers that produce much better bass on paper, to me, no speaker (OK, maybe his own personal O subwoofers, which I happen to have in my home) has ever made bass that was more perfect (actually, it's not even close) in terms of sounding like actual music. I admit that it's something that haunts one forever. Here's hoping one day I find a pair... |
Weseixas, I would think it would be much easier to get correct phase with a sealed box than with a port. |
"Duke, we have all read that bass is omni-directional, and yet very often it's very easy hear where the sub-woofer is (perhaps it's because the overtones appear to come elsewhere?)." - Unsound
"Bass localization is detectable indoors" - Weseixas
Hearing the location of a subwoofer is not necessarily the same thing as hearing the direction that low frequencies are coming from. Subs can be generating harmonic distortion that is more audible than the actual fundamental, and they can be passing lower midrange energy at a level that is still audible. We easily hear where a bass instrument is in the soundstage from the overtones and other higher frequency sounds (drumskin).
"Despite the theories, some of us clearly prefer the sound of sealed boxes over ported ones. As the old cliche' goes; "the proof of the pudding is in the eating"." - Unsound
If you re-read my theory, it is consistent with your observation.
"...get the math wrong and you will know, phase is absolutely critical." - Weseixas
Phase is audible in the bass region only to the extent that it impacts frequency response. So when you hear a difference after adjusting the relative phase of your subs, or their distance relative to the mains, what you are hearing is the effect on the frequency response.
Duke |
Hello Unsound ,
Are you talking acoustic or time , the rise time on a sealed cabinet is slower than that of a reflex, compare the square wave response.
Now if running tubes, subjectively there is some argument, tubes have poor damping and hence very little bass control to speak off , a sealed enclosure might be an advantage here, TL too , due to the loading.
regards, |
Phase is audible in the bass region only to the extent that it impacts frequency response. So when you hear a difference after adjusting the relative phase of your subs, or their distance relative to the mains, what you are hearing is the effect on the frequency response. - Audiokinesis
Ok Duke ... LOL, Hence Bass localization.
Now if you move the woofer outputs closer to mid ceiling the effect will be minimized to almost nothing.
Bass column-circa 1988
Regards, |
My question for you guys is what is having the most affect on our perception? More even pressure front? Or simply better stereo effect?
I have experienced the localization Wes is talking about and at frequencies below 80 Hz, which is where some claim our ability to localize is severely diminished. Adding an additional sub has rectified this issue for many and adding second bass horn did the same for me. And I find both don't need to be driven as hard as a single. |
Now if running tubes, subjectively there is some argument, tubes have poor damping and hence very little bass control to speak off , a sealed enclosure might be an advantage here, TL too , due to the loading. Actually in practice the reverse is true. Vented boxes usually need less damping of the driver for optimal response if I have my theory right- so less damping from the amplifier will be needed. So you can have plety of bass control! No speaker known requires a damping factor of above 20:1. That can be created by any tube amplifier, given enough feedback. However you pay a price for adding feedback- while you get more damping, you also add odd-ordered harmonic distortion, which essentially is audible as brightness and harshness. So if you want tubes to give you the best they can offer, its in your best interest to use an amplifier without feedback, and a speaker that is intended for an amplifier with a higher output impedance. The only thing about this is that loop feedback contributes to harshness in transistor amplifiers too. Since the ear/brain system uses the 5th, 7th and 9th harmonics as a means of determining how loud a sound is, messing with these harmonics will cause the system to sound louder than it really is, plus the odd orders are perceived as harshness. So there is a powerful argument for eliminating feedback altogether, as figuring out how loud a sound is is arguably one of the more important rules of human sound perception. IOW, the model of an amplifier with an output impedance of zero ohms may not hold water, given other real-world issues. So designing a speaker for that may not make a lot of sense either. |
It was certainly the case for me that an Atma-sphere S-30 gave me much improved bass over the solid state amp (Pass Aleph 30) I had previously, which had a much higher damping factor. With my 96 dB efficient drivers in a ported box, the Aleph overdamped my bass. |
The BC ref1000m monoblocks I use have damping factor spec of 1000 I believe.
I use them with Dynaudio monitors and OHM Walsh speakers.
The OHMs in particular have a reputation as benefiting from high damping so this is something I sought specifically.
The bass is the most articulate and rewarding over-all I have ever had with both.
Damping is a useful spec to consider when attempting to match speakers to amp for best results.
Some speakers may benefit from high damping and others not, either by accident or design. |
Hi Guys,
A question for a couple of you hard core amp guru's. I have and have seen you guys here mainly discussing Damping factor. In the past, I have also looked at how an amplifier slew's. Is this no longer a factor in todays amplifier designs? Slew rate/Input/Output? |
Certainly it is! The slew rate (or risetime) is a measure of how fast the amplifier can respond to a signal. The quicker it responds, the more likely the signal will be processed by the emotional centers of the brain (limbic system) rather than the cerebral cortex. This is where toe-tapping comes from.
Mapman, a damping factor of 1000... well let's put it this way- you won't hear the difference between that and an amplifier with a DF of 50, all other things being equal (which, it seems, they never are...). Its my guess that there are other things that are making that work for you. |
It was certainly the case for me that an Atma-sphere S-30 gave me much improved bass over the solid state amp (Pass Aleph 30) I had previously, which had a much higher damping factor. With my 96 dB efficient drivers in a ported box, the Aleph overdamped my bass. -Roscoeiii
Roscoeiii, Are you saying the S30 had more bass or improved Bass?
Atmasphere:
The vented box will need an amp with good bass control to sound proper, especially after roll off.
I cannot see the bass from tubes having more control, well actually never heard that before, i know yours are OTL's and most tubes are not , but your amplifiers do have a high output impedance, based on such i would prefer to run your amplifier with 16 ohm bass speakers, which will half your output power, but allow better control and less distortion due to impedance mis-match.
A question , any reason why 6LQ6 tubes are no longer being used today..
regards,
|
Both more and improved bass from the Atma-sphere. My speakers's bass has sounded best from the Atma-sphere S-30 and the FirstWatt F1 and F2. Didn't have the chance to directly compare the S-30 and the FirstWatts, but what they all have in common is a low damping factor. |
Hello Roscoeiii
Could you tell us the speaker ?
regards, |
Weseixas, actually with many tube amps when you increase the load impedance the output power goes *up* not down.
In the case of transformer coupled amps, this is because the OPT is more efficient. In the case of OTLs (and especially if its a *smaller* OTL), this is because the entire output section is running more efficiently- more power is dissipated in the load and less in the output section.
Bass extension has nothing to do with output impedance. Bass 'control' might, but since damping plays such a minor role here, what really is important is distortion. That's what gets you muddy bass! So if the amp is undistorted its more likely to be perceived as 'control'. Just FWIW.
Anyway, if the speaker was designed on tube amps, its unlikely that a transistor amp will exhibit more 'control'. My impression is that transistor amps in this situation exhibit 'punch' but not a lot of definition or subtlety. I often find myself trying to turn them up to get the same impact I expect out of the tube (in this case, OTL) amp. I guess my point is that so much depends on the interface between the amp and speaker that its very hard to make generalities. |
Hello Atmasphere,
what's the story regarding 6LQ6 tubes, any reason why they are no longer being used ? |
They were made for TVs and got phased out in the 1970s. It just so happened that if wired right, they could be operated with low voltage and high current, and so were useful in OTLs. Today they are pretty rare. The closest thing to them is the EL509, which is not as gutsy. |
