Owners Manual for Altec N800 Crossover Mounted in Speaker
This manual is for a version of the Pete Riggle Altec N800 Circuit Crosover with the crossover board in the speaker box and the control panel mounted on the rear of the speaker box.
Pete Riggle Crossover, Altec N800F Modified to Lpad Control, Crossover Board Internal to Speaker Box, Control Panel Mounted on Rear of Speaker Box, Supertweeter Circuit Included
The Altec N800F circuit was used by Altec for a number of speakers with the 811 tweeter. I have compared the N800F and Hiraga circuits on my Altec A7-500-8 speakers. The N800F circuit crosses at 890 Hz into 8 ohms (the nominal impedance of the A7-500-8 speakers). The Hiraga 8 Ohm circuit crosses at about 600 Hz into 8 ohms. Thus the the woofer goes higher with the N800F than with the Hiraga circuit. The Hiraga and N800F circuits sound very much alike on my A7 speakers. It would be difficult to choose one over the other.
As the title says, this version of the Lpad controlled N800F is for the customer who wants the crossover board internal to the speaker box, with the controls mounted on the rear of the speaker box.
Like all of the Pete Riggle High Performance Crossovers, this crossover is available with or without a supertweeter control circuit. The supertweeter control circuit has an on/off switch that engages or disengages the supertweeter. With the supertweeter control circuit engaged, a high pass signal is sent through a blocking capacitor (10 kHz 3 dB down point) to terminals for the supertweeter. A pair of supertweeter terminals is provided on the crossover board internal to the speaker box. A separate pair of supertweeter terminals is provided on the control panel mounted on the rear of the speaker box. The supertweeter can be connected internally or externally, but not both.
Control Panels
Here is a photo of the control panels intended to be mounted on the rear of the speaker box.
The Altec N800F circuit was used by Altec for a number of speakers with the 811 tweeter. I have compared the N800F and Hiraga circuits on my Altec A7-500-8 speakers. The N800F circuit crosses at 890 Hz into 8 ohms (the nominal impedance of the A7-500-8 speakers). The Hiraga 8 Ohm circuit crosses at about 600 Hz into 8 ohms. Thus the the woofer goes higher with the N800F than with the Hiraga circuit. The Hiraga and N800F circuits sound very much alike on my A7 speakers. It would be difficult to choose one over the other.
As the title says, this version of the Lpad controlled N800F is for the customer who wants the crossover board internal to the speaker box, with the controls mounted on the rear of the speaker box.
Like all of the Pete Riggle High Performance Crossovers, this crossover is available with or without a supertweeter control circuit. The supertweeter control circuit has an on/off switch that engages or disengages the supertweeter. With the supertweeter control circuit engaged, a high pass signal is sent through a blocking capacitor (10 kHz 3 dB down point) to terminals for the supertweeter. A pair of supertweeter terminals is provided on the crossover board internal to the speaker box. A separate pair of supertweeter terminals is provided on the control panel mounted on the rear of the speaker box. The supertweeter can be connected internally or externally, but not both.
Control Panels
Here is a photo of the control panels intended to be mounted on the rear of the speaker box.
Here is of the rear of a control panel.
Crossover Boards
Here is a photo of one of the crossover boards that mount internal to the speaker box.
Here is a photo of one of the crossover boards that mount internal to the speaker box.
Here is a photo of the internal crossover board terminals:
Connections Between Crossover Board and Control Panel
Five connection wires are required between the crossover board internal to the speaker box and the control panel mounted on the rear of the speaker box. These are 1) amplifier input negative terminal, 2) amplifier input positive terminal, 3) tweeter negative terminal, 4) supertweeter negative terminal, and 5) tweeter filter output (which connects the filter output on the crossover board with the control panel). The control panel support blocks are drilled through at the sides to allow access of the connecting wires to the terminals without draping the wires over the control panel.
Five connection wires are required between the crossover board internal to the speaker box and the control panel mounted on the rear of the speaker box. These are 1) amplifier input negative terminal, 2) amplifier input positive terminal, 3) tweeter negative terminal, 4) supertweeter negative terminal, and 5) tweeter filter output (which connects the filter output on the crossover board with the control panel). The control panel support blocks are drilled through at the sides to allow access of the connecting wires to the terminals without draping the wires over the control panel.
Combining the Crossover Board and the Control panel as a Stand-Alone Unit External to the Speaker Cabinet
In the event the user wishes to use the crossover board and the control panel as a unit external to the speaker box, the control panel support blocks are notched to allow the control panel to rest securely atop the crossover board front and rear panels. See the photos below:
In the event the user wishes to use the crossover board and the control panel as a unit external to the speaker box, the control panel support blocks are notched to allow the control panel to rest securely atop the crossover board front and rear panels. See the photos below:
Calculated Electrical Response Curves:
Calculated crossover unit electrical response curves (for 16 Ohm loads) with the crossover acting in the 2-way mode and the tweeter electrical signal level adjusted to match the woofer electrical signal level are shown in the image immediately below. The solid blue curve represents the combined response with tweeter phase inverted, which is achieved by connecting the positive and negative terminals of the woofer and tweeter to the respective positive and negative terminals of the crossover board.
Electrical response curves with the tweeter electrical level set 4 dB above the woofer electrical level are shown immediately below. The red curve is the combined response with inverted tweeter phase.
The dotted curves are phase response curves.
Calculated crossover unit electrical response curves (for 16 Ohm loads) with the crossover acting in the 2-way mode and the tweeter electrical signal level adjusted to match the woofer electrical signal level are shown in the image immediately below. The solid blue curve represents the combined response with tweeter phase inverted, which is achieved by connecting the positive and negative terminals of the woofer and tweeter to the respective positive and negative terminals of the crossover board.
Electrical response curves with the tweeter electrical level set 4 dB above the woofer electrical level are shown immediately below. The red curve is the combined response with inverted tweeter phase.
The dotted curves are phase response curves.
Electrical response curves with the tweeter electrical level set 4 dB above the woofer electrical level are shown immediately below. The red curve is the combined response with inverted tweeter phase.
The dotted curves are phase response curves.
The dotted curves are phase response curves.
Electrical response curves with the tweeter and woofer electrical levels set the same are shown below for cases where the tweeter is in phase with the woofer (tweeter connection to the crossover board reversed) and where the tweeter is out of phase with the woofer (tweeter connection to the crossover board not reversed) are shown immediately below.
The red curve represents the combined response with the tweeter out of phase. The green curve represents the combined response with the tweeter and woofer in phase. These curves suggest that if the woofer and tweeter voice coils are the same sound travel distance from the listener's ear, the tweeter should be connected as indicated by the crossover board terminals; and that if, at the crossover frequency, the tweeter voice coil is half a wave length further away from the listener's ear than the woofer voice coil, the tweeter connection should be switched from that indicated by the crossover board terminals. There is nothing to prevent the listener from trying both tweeter connections to determine by listening which connection is preferred.
The Supertweeter Circuit
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 disengaged, the electrical response curves are as shown in the preceding figures. With the supertweeter engaged the supertweeter operates in parallel with the tweeter and phase with the tweeter. In this case the supertweeter Lpad is blocked by a 2 microfarad capacitor located on the rear of the control panel. 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.
A capacitor blocked supertweeter circuit behaves well. With the supertweeter Lpad turned 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 combined 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.
Lpad Controls
Lpad controls for the tweeter and supertweeter reduce the effect of impedance variations of the tweeter and supertweeter. The supertweeter Lpad is slaved to the tweeter Lpad. The result is that when the supertweeter is dialed into the preferred output relative to the tweeter, the tweeter Lpad controls simultanously raises or lowers the tweeter and supertweeter volumes by the same amount.
Use of the N800F crossover for Drivers of Various Impedances
I was at first surprised by Altec's use of the N800F circuit for the Malibu speakers which combine two 12 inch 16 ohm woofers into 8 Ohms effective impedance, in combination with a 16 Ohm compression driver. However this caused me to investigate the electircal response of the N800F with the four various combinations of 8 and 16 Ohm drivers . . . 16 Ohm woofer with 16 Ohm tweeter, 8 Ohm woofer with 16 Ohm tweeter, 16 Ohm woofer with 8 Ohm tweeter, and 8 Ohm woofer with 8 Ohm tweeter.
Woofer (Ohms) Tweeter (Ohms) Crossover Frequency (Hz) Response Variation (dB)
16 16 1135 +1.1/-.4 Valencia spkr.
8 16 890 +0/ -2.6 Malibu spkr.
8 8 900 +0 /-2.7 A7-800 spkr.
16 8 900 +1.3 /-1.2
Because for the various combinations of impedance there is so little variation in response with frequency, I offer only one version of the N800F. I have heard and heartily approve of the N800F crossover with the Valencia, Malibu, and A7 speakers.
Circuit Diagram For 2 way N800F Crossover internal to the speaker box
Important Note: The circuit diagram below shows 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 disengaged, the electrical response curves are as shown in the preceding figures. With the supertweeter engaged the supertweeter operates in parallel with the tweeter and phase with the tweeter. In this case the supertweeter Lpad is blocked by a 2 microfarad capacitor located on the rear of the control panel. 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.
A capacitor blocked supertweeter circuit behaves well. With the supertweeter Lpad turned 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 combined 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.
Lpad Controls
Lpad controls for the tweeter and supertweeter reduce the effect of impedance variations of the tweeter and supertweeter. The supertweeter Lpad is slaved to the tweeter Lpad. The result is that when the supertweeter is dialed into the preferred output relative to the tweeter, the tweeter Lpad controls simultanously raises or lowers the tweeter and supertweeter volumes by the same amount.
Use of the N800F crossover for Drivers of Various Impedances
I was at first surprised by Altec's use of the N800F circuit for the Malibu speakers which combine two 12 inch 16 ohm woofers into 8 Ohms effective impedance, in combination with a 16 Ohm compression driver. However this caused me to investigate the electircal response of the N800F with the four various combinations of 8 and 16 Ohm drivers . . . 16 Ohm woofer with 16 Ohm tweeter, 8 Ohm woofer with 16 Ohm tweeter, 16 Ohm woofer with 8 Ohm tweeter, and 8 Ohm woofer with 8 Ohm tweeter.
Woofer (Ohms) Tweeter (Ohms) Crossover Frequency (Hz) Response Variation (dB)
16 16 1135 +1.1/-.4 Valencia spkr.
8 16 890 +0/ -2.6 Malibu spkr.
8 8 900 +0 /-2.7 A7-800 spkr.
16 8 900 +1.3 /-1.2
Because for the various combinations of impedance there is so little variation in response with frequency, I offer only one version of the N800F. I have heard and heartily approve of the N800F crossover with the Valencia, Malibu, and A7 speakers.
Circuit Diagram For 2 way N800F Crossover internal to the speaker box
Important Note: The circuit diagram below shows 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.
In Conclusion
I hope you find the above information on the Pete Riggle version of the Altec N800F circuit crossover useful. Please contact me if you find yourself with questions or concerns. Telephone: 509 582 4548 . Email: peteriggle@msn.com.
Pete Riggle
Kennewick, WA, United States
June 24, 2021
I hope you find the above information on the Pete Riggle version of the Altec N800F circuit crossover useful. Please contact me if you find yourself with questions or concerns. Telephone: 509 582 4548 . Email: peteriggle@msn.com.
Pete Riggle
Kennewick, WA, United States
June 24, 2021
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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 © 2021 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 © 2021 Pete Riggle Audio, All Rights Reserved.