Supertweeter Circuit Option for Pete Riggle High Performance Loudspeaker Crossover Networks
For a price of $300 per pair, any Pete Riggle High Performance Loudspeaker Crossover Network can be fitted with an optional supertweeter circuit.
Important Note: The circuit diagram for supertweeter connection the supertweeter piggy-backed off of the tweeter. The idea behind this arrangement is that the user would adjust the supertweeter relative to the tweeter, after which adjusting the tweeter level would handle the entire treble adjustment. This was a reasonable idea, but I have found that the supertweeter sounds clearer if it is driven directly from the amplifier + input of a single amplifier crossover or driven from the treble amplifier + input of a biampable crossover. Until I make time to publish a modified circuit diagram, here is the change that is needed: Disconnect the supertweeter switch from terminal 2 of the tweeter L-pad and reconnect the switch to the power amplifier + input of the crossover for a single amplifer installation, or to the treble power amplifier + input of a biampable crossover.
For crossovers with the supertweeter circuit, a switch is included which engages the supertweeter circuit if toggled up, and disengages the supertweeter circuit if toggled down. With the supertweeter engaged the supertweeter operates in parallel with the tweeter and in phase with the tweeter. In this case the supertweeter Lpad is blocked by a capacitor. A 2 uF capacitor is used for an 8 Ohm tweeter. A 1 uF capacitor is used for a 16 Ohm tweeter. The 3 dB down point is approximately 10 kHz. With the supertweeter switched off, the crossover unit becomes a standard 2-way. With the supertweeter switched on, the crossover unit becomes what is termed a 2-1/2 way.
Supertweeter Effect
When appropriate supertweeters are switched in they add air to the sound, increase the height and width of the sound stage, and surprisingly, the bass seems more liquid and musical. I've observed this effect in more than one system and heard this observation by others on the effect of a supertweeter on apparent bass quality.
Calculated Behavior of a Capacitor Blocked Supertweeter
A capacitor blocked supertweeter circuit behaves well. Calculations showing the effect of a capacitor blocked supertweeter are shown at the following link.
Important Note: The circuit diagram for supertweeter connection the supertweeter piggy-backed off of the tweeter. The idea behind this arrangement is that the user would adjust the supertweeter relative to the tweeter, after which adjusting the tweeter level would handle the entire treble adjustment. This was a reasonable idea, but I have found that the supertweeter sounds clearer if it is driven directly from the amplifier + input of a single amplifier crossover or driven from the treble amplifier + input of a biampable crossover. Until I make time to publish a modified circuit diagram, here is the change that is needed: Disconnect the supertweeter switch from terminal 2 of the tweeter L-pad and reconnect the switch to the power amplifier + input of the crossover for a single amplifer installation, or to the treble power amplifier + input of a biampable crossover.
For crossovers with the supertweeter circuit, a switch is included which engages the supertweeter circuit if toggled up, and disengages the supertweeter circuit if toggled down. With the supertweeter engaged the supertweeter operates in parallel with the tweeter and in phase with the tweeter. In this case the supertweeter Lpad is blocked by a capacitor. A 2 uF capacitor is used for an 8 Ohm tweeter. A 1 uF capacitor is used for a 16 Ohm tweeter. The 3 dB down point is approximately 10 kHz. With the supertweeter switched off, the crossover unit becomes a standard 2-way. With the supertweeter switched on, the crossover unit becomes what is termed a 2-1/2 way.
Supertweeter Effect
When appropriate supertweeters are switched in they add air to the sound, increase the height and width of the sound stage, and surprisingly, the bass seems more liquid and musical. I've observed this effect in more than one system and heard this observation by others on the effect of a supertweeter on apparent bass quality.
Calculated Behavior of a Capacitor Blocked Supertweeter
A capacitor blocked supertweeter circuit behaves well. Calculations showing the effect of a capacitor blocked supertweeter are shown at the following link.
With the supertweeter Lpad turned fully up, and a supertweeter with the same sensitivity as the tweeter, the supertweeter circuit raises the combined response of the tweeter and supertweeter at frequencies above 10 kHz. As the supertweeter Lpad is turned down, the combined very high frequency response of the tweeter and the supertweeter may be lower than the response with the supertweeter circuit turned off. The result is that the supertweeter Lpad control is capable of raising or lowering the very high frequency response relative to to the 2-way.
Assuming a supertweeter sensitivity within +/- 4 dB of the tweeter sensitivity, I am comfortable with the result using an 8 or 16 Ohm supertweeter with either an 8 Ohm or 16 Ohm crossover.
If the supertweeters seem too dominant they can be tamed with the supertweeter circuit level control.
If the supertweeters do not produce sufficient effect, they can be made more prominent relative to the tweeter by reducing tweeter sensitivity at the tweeter (not with the tweeter L-pad). Tweeter sensitivity can be reduced using an input resistor at the tweeter red terminal and a bypass resistor between the tweeter red and black terminals. A table of resistor values for this purpose is presented immediately below. In this case the tweeter level control can bring the tweeter back up to the optimal level, with the supertweeter level control used to balance the supertweeter with the tweeter.
Tweeter Sensitivity Reduction
16 Ohm Tweeter 8 Ohm Tweeter
dB input R bypass R dB input R bypass R
-1 2 Ohms 130 Ohms -1 1 Ohm 70 Ohms
-2 3 60 -2 1.5 30
-3 5 40 -3 2.5 20
-4 6 27 -4 3 14
-5 7 20 -5 3.5 10
-6 8 16 -6 4 8
How to dial in supertweeters with Pete Riggle Crossovers
With Pete Riggle crossovers, the optional supertweeter circuit is piggy-backed off the output of the tweeter L-pad. The tweeter L-pad raises and lowers the supertweeter circuit along with tweeter level adjustment . This keeps the supertweeter and tweeter volumes in balance as the tweeter level is adjusted relative to the woofer. The supertweeter circuit operates with its own L-pad to tame the supertweeter if it is too loud.
As mentioned above, 8 and 16 Ohm Pete Riggle crossovers with the supertweeter circuit option use 2 uF and 1 uF supertweeter blocking capacitors, respectively, to roll the supertweeter down 3 dB at 10 kHz. Detailed calculations show that if the supertweeter sensitivity is within about 4 dB either way of the tweeter sensitivity, we can achieve desirable results with an 8 or 16 Ohm supertweeter used with an 8 or 16 Ohm Pete Riggle Crossover. With a 16 Ohm crossover, an 8 Ohm supertweeter will play a touch louder than a 16 Ohm tweeter. With an 8 Ohm crossover, a 16 Ohm supertweeter will play a touch less loud than an 8 Ohm supertweeter. Whatever the combination of crossover and supertweeter impedances, it would be beneficial practice to listen to the system with the supertweeters switched in and possibly adjust the supertweeter relative to the tweeter as discussed above.
Supertweeter Mounting
A supertweeter for Altec A7 speakers needs to be mounted to achieve time alignment between the supertweeter and tweeter diaphragms, and to be mounted high enough so that the mouth of the tweeter horn does not block sound radiation from the supertweeter. There are many mounting options. For Altec A7 speakers I mount the supertweeters with their axis 16 inches above the tweeter axis as shown in the photos below. The first photo is an image of the installation I recommend, followed by a sketch showing how to build a supertweeter stand like that shown in the photo.
Assuming a supertweeter sensitivity within +/- 4 dB of the tweeter sensitivity, I am comfortable with the result using an 8 or 16 Ohm supertweeter with either an 8 Ohm or 16 Ohm crossover.
If the supertweeters seem too dominant they can be tamed with the supertweeter circuit level control.
If the supertweeters do not produce sufficient effect, they can be made more prominent relative to the tweeter by reducing tweeter sensitivity at the tweeter (not with the tweeter L-pad). Tweeter sensitivity can be reduced using an input resistor at the tweeter red terminal and a bypass resistor between the tweeter red and black terminals. A table of resistor values for this purpose is presented immediately below. In this case the tweeter level control can bring the tweeter back up to the optimal level, with the supertweeter level control used to balance the supertweeter with the tweeter.
Tweeter Sensitivity Reduction
16 Ohm Tweeter 8 Ohm Tweeter
dB input R bypass R dB input R bypass R
-1 2 Ohms 130 Ohms -1 1 Ohm 70 Ohms
-2 3 60 -2 1.5 30
-3 5 40 -3 2.5 20
-4 6 27 -4 3 14
-5 7 20 -5 3.5 10
-6 8 16 -6 4 8
How to dial in supertweeters with Pete Riggle Crossovers
With Pete Riggle crossovers, the optional supertweeter circuit is piggy-backed off the output of the tweeter L-pad. The tweeter L-pad raises and lowers the supertweeter circuit along with tweeter level adjustment . This keeps the supertweeter and tweeter volumes in balance as the tweeter level is adjusted relative to the woofer. The supertweeter circuit operates with its own L-pad to tame the supertweeter if it is too loud.
As mentioned above, 8 and 16 Ohm Pete Riggle crossovers with the supertweeter circuit option use 2 uF and 1 uF supertweeter blocking capacitors, respectively, to roll the supertweeter down 3 dB at 10 kHz. Detailed calculations show that if the supertweeter sensitivity is within about 4 dB either way of the tweeter sensitivity, we can achieve desirable results with an 8 or 16 Ohm supertweeter used with an 8 or 16 Ohm Pete Riggle Crossover. With a 16 Ohm crossover, an 8 Ohm supertweeter will play a touch louder than a 16 Ohm tweeter. With an 8 Ohm crossover, a 16 Ohm supertweeter will play a touch less loud than an 8 Ohm supertweeter. Whatever the combination of crossover and supertweeter impedances, it would be beneficial practice to listen to the system with the supertweeters switched in and possibly adjust the supertweeter relative to the tweeter as discussed above.
Supertweeter Mounting
A supertweeter for Altec A7 speakers needs to be mounted to achieve time alignment between the supertweeter and tweeter diaphragms, and to be mounted high enough so that the mouth of the tweeter horn does not block sound radiation from the supertweeter. There are many mounting options. For Altec A7 speakers I mount the supertweeters with their axis 16 inches above the tweeter axis as shown in the photos below. The first photo is an image of the installation I recommend, followed by a sketch showing how to build a supertweeter stand like that shown in the photo.
A favorite supertweeter
A favorite supertweeter for me is the Harmon JBL branded Selenium ST400BLK supertweeter, an 8 Ohm bullet supertweeter, which is a super performer at a currently super bargain price of $130 USD per pair including shipping from Amazon. I use these supertweeters with great satisfaction. Do not let the low price scare you. See the following photo.
A favorite supertweeter for me is the Harmon JBL branded Selenium ST400BLK supertweeter, an 8 Ohm bullet supertweeter, which is a super performer at a currently super bargain price of $130 USD per pair including shipping from Amazon. I use these supertweeters with great satisfaction. Do not let the low price scare you. See the following photo.
Customer Assessment of JBL/Selenium Supertweeter
"Hi Pete, I just have about 2 hours of listening in, but I am happy that the soundstage and imaging are fully intact plus an extended range up giving some more airiness without being harsh. I am playing around with the volume, but I am sure they are a keeper. Thanks again for your assistance and recommendation. Best Regards, Harald Kneuer
"Hi Pete, I just have about 2 hours of listening in, but I am happy that the soundstage and imaging are fully intact plus an extended range up giving some more airiness without being harsh. I am playing around with the volume, but I am sure they are a keeper. Thanks again for your assistance and recommendation. Best Regards, Harald Kneuer
Hiraga Circuit Crossover Front and Rear Panels with Supertweeter Circuit Option
In conclusion of this page, the photos below show the front and rear panels of Hiraga circuit crossovers including the supertweeter circuit option. The covers have been removed.
In conclusion of this page, the photos below show the front and rear panels of Hiraga circuit crossovers including the supertweeter circuit option. The covers have been removed.
WHY USE A SUPERTWEETER?
THE ANSWER TO A CUSTOMER'S INQUIRY
Hi Guido!
With my Altec A7 speakers I've been using a capacitor blocked supertweeter with a blocking capacitor selected to attenuate the supertweeteer electrical signal by 3 dB just below 10 kHz. We get that with a 2 uF capacitor blocking an 8 Ohm load. This works subjectively very well in my system with the supertweeter L-pad all the way up or attenuated a few dB. When I simulate crossovers using a blocking capacitor that gives 3 dB down at 10 kHz, I find that the relatively slow rolloff of the supertweeter allows a contribution to the sound in the 5 to 10 kHz octave, substantial at 10 kHz and minimal at 5 kHz. The degree of the contribution depends on the setting of the supertweeter L-pad.
Because most older people do not hear the octave between 10 and 20 kHz, one might question why older people choose to use a supertweeter. Surprisingly, what we are hearing from the supertweeter, which is very apparent and not at all harsh, may be the result of better dispersion in the 5 to 10 kHz octave. I cannot answer that question conclusively. Some very credible audiophiles claim to hear benefits from frequency extension out beyond 20 kHz. A group of Japanese scientists made measurements showing brain response to frequencies high enough that the subjects claim not to hear them. What I can say from my experience is that Selenium supertweeters make a very beneficial contribution when used the way I have been using them.
One needs to take Altec's loudspeaker system upper frequency response specifications with a grain of salt. The output level at 20 kHz is not specified. Dispersion narrows when wavelengths become shorter than the circumference of the horn mouth, resulting in reduced total power output at high frequencies. I have looked extensively and unsuccessfully for horn supertweeters with substantial dispersion above 10 kHz. I know that the Altec 802-8D compression driver, with circular phase plug slots, falls off rapidly above 11 kHz. I understand that the 802-8G, with radial phase plug slots (the Tangerine phase plug) used in the Model 19 speakers extends the response a bit, possibly because some of the 8G models were made with thinner diaphragms than are now currently available. When I comparatively listened to 8D versus 8G compression drivers in my system, I did hear greater apparent high frequency output from the 8G but found the 8G to be less coherent and musical than the 8D. In my system I am now using Radian 475PB 8 Ohm drivers which provide more pleasant listening than the Altec 802-8D and 802-8G drivers.
The capacitor blocked supertweeter question is difficult to address rationally. In my opinion the Selenium supertweeter, used as I use it, only adds to listening satisfaction. Visitors to my listening room agree. I think it is the subjective results that matter. I currently configure my crossovers to drive the supertweeter blocking capacitor directly from the amplifier inputs. Therefore the supertweeter circuit does not interact with the woofer and tweeter filter circuits. The blocking capacitor feeds the combination of the L-pad and supertweeter, which provides a sufficiently constant resistance to maintain good rolloff behaviour. Counter to some opinions, I have never been aware of a system degradation attributable to L-pads.
I hope you find this helpful.
Kind Regards,
Pete
___________________________________________________________________________
Pete Riggle Audio
2112 S. Olympia Street, Kennewick WA 99337, USA
shop phone: 509 582 4548 email: peteriggle@msn.com
VTAF™ Trademarked. U.S.Patent No. 7630288.
Website content Copyright © 2023 Pete Riggle Audio, All Rights Reserved.
Pete Riggle Audio
2112 S. Olympia Street, Kennewick WA 99337, USA
shop phone: 509 582 4548 email: peteriggle@msn.com
VTAF™ Trademarked. U.S.Patent No. 7630288.
Website content Copyright © 2023 Pete Riggle Audio, All Rights Reserved.