I have examined many TBs. From the data collected a notch below thew MA on QC and tight tolerances.
And i don/t klnwforsure but i guess TB has a higher prifit margin then MA.
dave
And i don/t klnwforsure but i guess TB has a higher prifit margin then MA.
dave
I built these and they sound great.
Well, as a life-long audiophile-purist (defined elsewhere) I hesitate to join the fray, in a forum where frankly some members listened and spoke through measurements. Put most succinctly, reasonably extended, flat frequency response is necessary for high-fidelity music in several ways: reproduction of fast transcients and finest detail; dynamic-articulation esp. 5khz; realistic tonality of musical instruments esp. 7-10khz; soundstage imaging and venue air esp. above 10khz. (Like @perceval) I have not found a purist whizzer-less fullrange driver to pass muster without at least some enhancement (whizzer, notch, stacking, LX etc.), but whizzers tend to shout (listening off-axis to avoid 7-8khz shout gave up all higher frequency). As for multi-way, @tmuikku once showed a set of very simple simulation curves of ideal drivers and textbook XO, whose impulse response had much greater distortion than a single bandwidth-limited fullrange driver (as measured by area ratio in-common-with-source/symmetric-difference-from-source). This is before even considering time-alignment, phase-alignment, center-to-center/comb-filtering, XO parts quality and tolerance (not to mention cost), and so on. So what to do?
My method-to-the-madness is to take drivers that are outstanding in SQ areas I most care about (none are perfect), and try to "solve" their shortcomings in a minimalist way (as would @planet10 whom I consider a mentor) -- fullrange or multi-way both (so they really are both, in spirit and technique). Often unusual or surprising, many have been reported here on diyaudio (or bbs.hifidiy.net in Chinese).
My method-to-the-madness is to take drivers that are outstanding in SQ areas I most care about (none are perfect), and try to "solve" their shortcomings in a minimalist way (as would @planet10 whom I consider a mentor) -- fullrange or multi-way both (so they really are both, in spirit and technique). Often unusual or surprising, many have been reported here on diyaudio (or bbs.hifidiy.net in Chinese).
The Genelecs are $10,000 for a pair, far too large for any desktop and a 3 way design……..and you’re asking for a single driver desktop equivalent for less than a grand? I don’t think I need to point out the absurdity of your expectations. I think we can check a full range single driver solution off the list. 🤣
Many TBs at the same price range of the Maop11 in this case? Doubt it.
So, now we are guessing how much margin a company makes on drivers. Geez.... enough.
Make sure you decouple the enclosures from the desk. The desk will induce resonances. There are pads designed for that.
For 4 figures there's always the Cube F8 Magus and 10" models. Though you might have to make the boxes floor-standing, and maybe 'C' shaped so they crane over the desk.
Rolling off the high frequencies is just a minor side-effect that is easily fixed with EQ. One thing I'd watch out for is that the amplifier doesn't run out of head-room if you end up boosting the treble by 10dB or so. Though with most music there is a lot more energy in the bass.
The M.A. may be good or even great, but I could bet that the speaker impedance does not remain perfectly steady everywhere within the 'Xmax' range.
That's great. But as you can see, people spend thousands to gain fractional improvements in sound, so where's the harm in suggesting something simple like a 0.500mH Jansen coil (26 gauge, 1.5 ohm) that costs around $4?
Rolling off the high frequencies is just a minor side-effect that is easily fixed with EQ. One thing I'd watch out for is that the amplifier doesn't run out of head-room if you end up boosting the treble by 10dB or so. Though with most music there is a lot more energy in the bass.
The M.A. may be good or even great, but I could bet that the speaker impedance does not remain perfectly steady everywhere within the 'Xmax' range.
Choose coaxial system for shorter nearfield transition distance.
Which is their business of course, nobody's arguing that point (I hope 😉 )
Well, if you want me to be honest, I'd say (speaking in the context of P7HD):
a/ the drivers are featherweight loads to start off with, and as far as the actual electrical load is concerned they won't cause the slightest difficulty for anything north of a crystal radio,
b/ I've yet to see a class D amplifier acting like a current source (most tend to high very low output impedances) so the FR will not follow the impedance curve
c/ if you want to cancel out the rising impedance you'd do better to use a reactance annulling Zobel, not a series inductor, which causes additional HF impedance rise, and
d/ inductors don't 'demodulate treble' (or at least they don't as-read -could you be more specific about what you're referring to?)
Setting aside baffle effects etc. (separate issues) what you in essence achieve is a higher HF impedance and a slightly shelved low pass effect, which then requires additional EQ to compensate for. Attached: this is the IEC frequency response of P7HD, grey 'as-is', blue with a 0.5mH inductor, 0.05ohm DCR in series. Impedance plot shows the 'raw' direct-coupled driver in a Butterworth aligned sealed box, blue with the inductor added in. Nothing surprising of course, but I can't see what the improvements you mention are?
You can fix the losses with EQ, certainly. But not everybody wants to use electronic EQ (or has the facilities to do so), & in this case, it seems like it's being used to compensate for losses that didn't exist before the addition was made. I'm obviously missing something, but at the moment, I'm not sure what.
You're very unlikely to run out of headroom in the HF with anything more than a spud amp. Most music power demands exist < 500Hz & energy falls off very quickly above that -good job too or most tweeters would be blasted into the next room, assuming our hearing survived the experience 😉
Well, you've got the impedance curve, & as you can see it's a symmetric drive type motor design; there will be some asymmetry somewhere because all drivers have that, but a 0.5mH inductor isn't going to address it (whereever / whatever its specific details might be -you'd need to take Le(x) & Klippel based measurements to know the details & what fixes may or may not be practical.
Attachments
Last edited:
I dug this up from a Klippel paper:I'm obviously missing something, but at the moment, I'm not sure what.
Klippel loudspeaker nonlinearities pdf
Below that they also mention inductance modulation due to voice-coil current. So at high frequencies like 10kHz, the key point is to divide the distorting part of the inductance down to a smaller fraction of the total impedance.
Some argue that since motor force is in Newtons per ampere, current drive is therefore the ideal, with practical examples probably between 10s of ohms (Pass F1, F2?) up to maybe 1k ohm. But I think there's a case of diminishing returns, and conflicting behaviour in the bass (actively discussed in a couple of current drive threads).
Where speaker impedance has peaks at low frequencies, voltage drive has a lot of advantages, like concentrating the voltage across the part of the coil where the magnetic field is strongest.
Something like 4.7 - 22 ohms in series is a super easy hack to get a feel for any audible differences, though the weak spot would likely be the bass. A small inductor (say, 500uH, air cored) takes that to the next level, giving 10s of ohms at HF, while passing bass with whatever the DC resistance is. But as you rightly said, active EQ could be a stumbling block.
Thinking about this, given the competitive marketplacew i expect both companies have razor thin margins. TB gets a big hand from their big OEMJ clients.
None of the TB (except for a pair of 3” prototyped i have) did not impress me.
There are many makers because there are many tastes and requirements.
dave
Yes, that's the Le(x) test (and some more involved ones).
Which is one reason symmetric drive (in Scan Speak parlance -it was around for many years prior to that 😉 ) exists. The more linear your basic impedance load is, the higher the probability it will remain consistent at higher drive levels / excursions. While not foolproof (that's why Le(x) etc. testing exists of course), it's a reasonable guideline in the absence of anything else.
It looks like we're moving away a bit from drive units into the voltage / current source amplifier debate. It's an interesting one, since they ultimately form a summed system, but beyond the basic fact that a driver with a more linear impedance load tends to remain that way in both cases, while those with more basic motors also show more changes as electrical damping from the amplifier is reduced, we seem to have deviated a bit. Either way, whatever its other merits / demerits may (or may not 😉 ) be, P7HD in that sense is one of the most linear loads you're likely to find.
As in at driver resonance or around system tuning?
It might; OTOH it might not. Depends what you're doing; ideally you design an LF load for the effective system Qts' (as in driver Q with any relevant amplifier output impedance / series R in circuit), so this varies according to the expected amplifier. In a number of cases this was expected (historically many Fostex & Lowther units) & if you deviated you were moving outside the intended operating region.
Agreed, that's a straightforward enough approach to experimenting with reducing the electrical damping (or artificially raising effective Q) & how it can affect behaviour. I design a lot of my own speakers assuming general types of amplifier, or equivalent compensation. I've done a couple of small ranges of enclosures assuming different amounts of series R as functional components for the target alignment too, which can be quite interesting to play with. Back in the day, it wasn't unusual to have amplifiers with variable output impedance so you could more easily dial in the system alignment. Sadly it seems to have been far too logicial, so vanished about 6 decades ago.
So much for 'progress'. 😉Apologies: I'm probably a bit dense, but I'm still not seeing where the advantages are. Possibly somewhere up-chain, assuming you also add in appropriate compensation for the losses caused, but this is also going to depend heavily on the amplifier's characteristics; you're not going to get improvements this way on the end of Class D etc. in itself; you're just changing the load characteristic. I'm interested in variable output impedance designs (I'd love to see some of those back) & some high output impedance types too if accounted for in the design itself (love some of Nelson's work, obviously), but I still don't follow how sticking a 0.5mH inductor in series with a P7HD on the end of class D amplifiers is bringing any benefits.
Last edited:
Scottmoose
Now it is really too difficult to understand what you write for an amateur.
Impressed by your knowledge. Most of them just listen and like the sound so and so.
Choosing an amplifier that suits a driver is difficult for an amateur.
Have a few different amps to test with. Class D, Tubes 6550c, Class AB.
Of course they sound different.
Now it is really too difficult to understand what you write for an amateur.
Impressed by your knowledge. Most of them just listen and like the sound so and so.
Choosing an amplifier that suits a driver is difficult for an amateur.
Have a few different amps to test with. Class D, Tubes 6550c, Class AB.
Of course they sound different.
Is there a greater chance that there will be a more audiophile result to use a closed box and a suitable driver for this? Qts 0.45-0.85
I'll pass on that one as I'm not (and don't want to be 😉 ) an audiophile.
Re the previous -sorry, not my intent. This isn't a python-measuring contest & the day I stop learning is the day I give up -there are people here who've forgotten more than I'll ever know & I owe what little I do know to. As for the amplifiers -sure, they'll certainly sound different 'as-is' for a whole host of reasons, one of them being their output impedance: the higher that is, the lower the amount of electrical damping you have & the more the frequency response will start to deviate from what you think you had, and actually start to follow the impedance curve. Seriously though -if you want me to clarify any of my wittering, for the love of Mike don't worry about asking!
Re the previous -sorry, not my intent. This isn't a python-measuring contest & the day I stop learning is the day I give up -there are people here who've forgotten more than I'll ever know & I owe what little I do know to. As for the amplifiers -sure, they'll certainly sound different 'as-is' for a whole host of reasons, one of them being their output impedance: the higher that is, the lower the amount of electrical damping you have & the more the frequency response will start to deviate from what you think you had, and actually start to follow the impedance curve. Seriously though -if you want me to clarify any of my wittering, for the love of Mike don't worry about asking!
You managed to get a KEF LS50 coaxial unit ???!!! 😲 How much? Can you reveal your secret source?