soongsc,
Though others may have an aversion to tone controls I am not one of those people. As long as you can bypass those controls at times so you can understand what the sound would be without them. As you say the level changes do change the sound balance and a simple tone control as Doug Self uses in his preamp designs is fine with me.
Though others may have an aversion to tone controls I am not one of those people. As long as you can bypass those controls at times so you can understand what the sound would be without them. As you say the level changes do change the sound balance and a simple tone control as Doug Self uses in his preamp designs is fine with me.
Some of Doug Self's ideas have been studied, and he goes through lots of different configurations in his book. I have also been though lots of other publications as well.
I used to be one of those that just don't want tone controls until I worked on equalizing the Exaltations in the amp. It seems that in the past impedance variation from stage to stage had not been thoroughly considered, so this is an important consideration of mine. Additionally, what would be the steps to shap the frequency response and how it effects phase is another area of concern. Will there be a bypass? It is possible, and probably benefit the user in the process of listening comparison. These are going to be part of the power amplifier since I expect them to stay fixed once properly set. Also still thinking about a polarity switch to make sure something can be done if something upstream inverts polarity.
Finding a reference speaker to test out these things is also going to be tough. It would be even more tedious to test in different systems.
I used to be one of those that just don't want tone controls until I worked on equalizing the Exaltations in the amp. It seems that in the past impedance variation from stage to stage had not been thoroughly considered, so this is an important consideration of mine. Additionally, what would be the steps to shap the frequency response and how it effects phase is another area of concern. Will there be a bypass? It is possible, and probably benefit the user in the process of listening comparison. These are going to be part of the power amplifier since I expect them to stay fixed once properly set. Also still thinking about a polarity switch to make sure something can be done if something upstream inverts polarity.
Finding a reference speaker to test out these things is also going to be tough. It would be even more tedious to test in different systems.
Lynn,
Have you ever considered series crossovers?
I have tried some, and they seem more natural to me than parallel crossovers, but I never dug in to find out why. I do recall that a pair of speakers called "The Ultimate Monitors" used such as well, wonder of anyone here has heard them or not.
Have you ever considered series crossovers?
I have tried some, and they seem more natural to me than parallel crossovers, but I never dug in to find out why. I do recall that a pair of speakers called "The Ultimate Monitors" used such as well, wonder of anyone here has heard them or not.
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Does anybody know about such a autoformer with 1 db taps as Lynn is recommending?
Attenuator: Precision wirewound discrete-resistor L-Pad, or custom autoformer or transformer with 1 dB taps in the 12~15 dB range. The autoformer uses a 16-ohm shunt resistor in parallel with the primary, and the discrete L-pad presents a 16-ohm load to the passive highpass filter.
Attenuator: Precision wirewound discrete-resistor L-Pad, or custom autoformer or transformer with 1 dB taps in the 12~15 dB range. The autoformer uses a 16-ohm shunt resistor in parallel with the primary, and the discrete L-pad presents a 16-ohm load to the passive highpass filter.
Crites has an autotransformer in the -12db max range, with 1db increments, and it's not bad, cost wise.
check out the 3636 model. The transformer will multiply the impedance of the driver it attenuates. The data sheet on this model shows "T/RSquared" in the right column for each level of attenuation. Multiply this number by the impedance of your driver, and that's the impedance your crossover will see. The 16 ohm resistor in parallel with the input keeps the impedance from varying as much, since driver impedance goes up at resonance, etc. A higher impedance seen by the crossover allows for a smaller series cap for the crossover. Once you settle on the crossover cap value you like due to cost, quality, available values, etc., you can vary the crossover frequency by changing the value of the parallel cap.
The autoformer also reduces the source impedance of the amp as seen by the driver, by the same "T/RSquared". In theory, this may improve damping. But there are those that say some series resistance, or "current source" drive, actually is better for some compression drivers, as in lower distortion.
Autotransformers | Critesspeakers.com
It would probably be best to dial in your crossover with an L-pad first, and select a cap value, to find out what level of attenuation you need before thinking about purchasing an autoformer. Or swap in descrete resistors.
I think that it is safe to say that "damping" in a compression driver is not an issue (remember that source impedance only affects EM damping.) A "Current Source" does reduce nonlinearities in the inductance but these are pretty small and nonlinearities in a compression driver are not really an issue anyways IMHO. I have never understood the transformer idea. Just sounds like something else to sell a customer. A couple of resistors work fine (but hey, that's only about a dollar, how can that be any good.
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I use autoformers by Dave Slagle of Intact Audio. I prefer their use over resistors with compression drivers.
I was a tech writer for nine years, and for much of that time, had access through Tektronix to the early Arpanet (mid-Eighties). One thing I never forgot as I warmed up to post on "rec.audio.high-end" was a comment from a passing writer: Never say anything on the Net you wouldn't mind a manager seeing ten or twenty years from now.
As the Arpanet grew into the Internet of the early Nineties, the BBS/PC culture of anonymous posting and "flaming" and "trolling" joined in. The Arpanet had different rules because an offensive post could be quickly traced to the guilty party, and his (and it was almost always "his") post brought to the attention of their manager. Access to the Arpanet was restricted to a select few universities, large companies with military contracts, and nuclear weapons labs. That kind of monkeyshines was an on-the-spot firing offense; almost the polar opposite of BBS culture, which was a kind of male-teenage-geek outlaw culture at the time.
After thirty-some years on the Net, I still don't see the appeal of anonymity, unless you're posting at work, or live in a dictatorship where making the wrong post could land you in prison. That's hardly the case here on diyAudio, where we discuss the most trivial subjects imaginable, yet people get really bent out of shape about it.
Resistors versus transformers? Really, who cares? We're not talking about the political situation in Ukraine, the byzantine complexities of the Mideast, or pathways of AIDS transmission in Africa. That affects the lives of millions of people; what we talk about doesn't.
News flash: the wider public sees high fidelity about as important as model trains. At least model trains are fun to look at as they whiz around the track; our stuff just sits there and looks like a leftover prop from the movie set of Frankenstein. If we're lucky, it sounds good (to us).
All we can do here is discuss our experiences, how-to's, measurement tips and tricks, share ideas, and be halfway decent to each other.
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Resistors can cost a lot as well, like Duelund resistor.I think that it is safe to say that "damping" in a compression driver is not an issue (remember that source impedance only affects EM damping.) A "Current Source" does reduce nonlinearities in the inductance but these are pretty small and nonlinearities in a compression driver are not really an issue anyways IMHO. I have never understood the transformer idea. Just sounds like something else to sell a customer. A couple of resistors work fine (but hey, that's only about a dollar, how can that be any good.
For sure they are going to sound different. I have tried different resistor technology, in series with a driver, they make a difference, although not directly proportional to cost.
I have not used autoformers, but considering budget permitting, I don't rule them out.
Yeah. I don't get the transformer thing in this application. Seems like an over complication.
These compression drivers need quite a bit of attenuation (mine are set at -17.5). If it were just a few dB's, resistors would probably be just fine. In my experience, compression drivers start to lose dynamics with significant resistive attenuation. With autotransformer attenuation, the sound just gets quieter but remains lively.
As an analogy, think of driving a car with a manual transmission. Using an autotransformer is like shifting into a lower gear instead of keeping one foot on the gas and the other on the brake.
If you prefer resistors, by all means go for it. But if you don't like the results, don't blame the design, which includes autoformer attenuators.
As an analogy, think of driving a car with a manual transmission. Using an autotransformer is like shifting into a lower gear instead of keeping one foot on the gas and the other on the brake.
If you prefer resistors, by all means go for it. But if you don't like the results, don't blame the design, which includes autoformer attenuators.
I think that it is safe to say that "damping" in a compression driver is not an issue (remember that source impedance only affects EM damping.) A "Current Source" does reduce nonlinearities in the inductance but these are pretty small and nonlinearities in a compression driver are not really an issue anyways IMHO. I have never understood the transformer idea. Just sounds like something else to sell a customer. A couple of resistors work fine (but hey, that's only about a dollar, how can that be any good.
The transformer produces its own sound signature, so while a decent power resistor will be technically fine, its that personal tone adjustment, while avoiding the degradation of an LCR tone control and messing up the phase profile. Less is more.
Off the subject a bit you guys. I need a bit of advice.
When designing a crossover for the Radian 165 (high-pass) see this graph. Radian High Frequency Compression Drivers - Radian 465PB - Radian 465PB 1" high frequency compression driver. Radian 465PB 1" high frequency compression driver is available here. Radian 465PB speaker components.
Is it bad practice to implement a 1st order at around 6000hz and be done? I know there's a big loss in efficiency but I only want around 98db anyway and the driver should only see a watt or three.
Thanks, Ron
When designing a crossover for the Radian 165 (high-pass) see this graph. Radian High Frequency Compression Drivers - Radian 465PB - Radian 465PB 1" high frequency compression driver. Radian 465PB 1" high frequency compression driver is available here. Radian 465PB speaker components.
Is it bad practice to implement a 1st order at around 6000hz and be done? I know there's a big loss in efficiency but I only want around 98db anyway and the driver should only see a watt or three.
Thanks, Ron