Hi All,
I have added a B&W DB1 sub-woofer to my passive-preamp + F5 combination, driving a pair of B&W 805D. I have connected the newly added sub-woofer by inserting an RCA splitter at the power-amp output terminals of the Creek OBH-22 passive pre-amp.
After adding the sub-woofer, I perceive a decrease in loudness / drive to the music, now I have to turn the volume knob slightly higher compared to before even though with the sub-woofer the lower bass has been filled in, and I feel that the music has less drive / sounds thin.
I wonder whether it would help to put a buffer like B1 after the passive preamp?
Best regards
Liu
I have added a B&W DB1 sub-woofer to my passive-preamp + F5 combination, driving a pair of B&W 805D. I have connected the newly added sub-woofer by inserting an RCA splitter at the power-amp output terminals of the Creek OBH-22 passive pre-amp.
After adding the sub-woofer, I perceive a decrease in loudness / drive to the music, now I have to turn the volume knob slightly higher compared to before even though with the sub-woofer the lower bass has been filled in, and I feel that the music has less drive / sounds thin.
I wonder whether it would help to put a buffer like B1 after the passive preamp?
Best regards
Liu
What is the sensitivity of the woofer channel compared to the sensitivity of the stereo channels?
Hi AndrewT,
I am not sure. The stereo channel has a sensitivity of 88 dB as stated in the info sheet. As for the subwoofer, in the info sheet of the subwoofer, it is stated to feature a 1000W class-D power amp, but the sensitivity of the drive unit itself is not stated.
I am not sure. The stereo channel has a sensitivity of 88 dB as stated in the info sheet. As for the subwoofer, in the info sheet of the subwoofer, it is stated to feature a 1000W class-D power amp, but the sensitivity of the drive unit itself is not stated.
the stereo channel will have speakers driven by an amplifier.
You need the volts at the input of the amplifier and the output of the speaker in dB of SPL.
You need the same information for the woofer channel.
Then you can identify whether the same voltage or a different voltage needs to be fed to the woofer channel.
88dB/W @ 1m for the stereo channel is 1/4 of the information you need.
You need the volts at the input of the amplifier and the output of the speaker in dB of SPL.
You need the same information for the woofer channel.
Then you can identify whether the same voltage or a different voltage needs to be fed to the woofer channel.
88dB/W @ 1m for the stereo channel is 1/4 of the information you need.
Well, I have actually not given this any thought before. I always assumed that a commerically sold subwoofer is designed to take the same signal that goes to the main speakers channel and just amplifies the signal through its built-in power amp.
Anyway, in the setup menu of the sub-woofer, I have chosen a sentivity level that corresponds to 2V input signal. I assume that having chosen this setting, the sub-woofer takes care of the question of aligning the subwoofer channel and the main speaker channel?
Anyway, in the setup menu of the sub-woofer, I have chosen a sentivity level that corresponds to 2V input signal. I assume that having chosen this setting, the sub-woofer takes care of the question of aligning the subwoofer channel and the main speaker channel?
Hi All,
I would like to have your input to whether a buffer is necessary in this scenario:
Computer -> USB DAC -> Passive Pre-amp (output impedence 20k Ohms) -> F5 (input impedence 100k Ohms) in parallel with Subwoofer (input impedence 15k Ohms)
Looking at the output impedence of the passive pre-amp and the input impedence of the sub-woofer, I am thinking that it is probably a good idea to add a buffer. Appreciate your inputs. Thanks.
I would like to have your input to whether a buffer is necessary in this scenario:
Computer -> USB DAC -> Passive Pre-amp (output impedence 20k Ohms) -> F5 (input impedence 100k Ohms) in parallel with Subwoofer (input impedence 15k Ohms)
Looking at the output impedence of the passive pre-amp and the input impedence of the sub-woofer, I am thinking that it is probably a good idea to add a buffer. Appreciate your inputs. Thanks.
The sub is too quiet compared to the stereo.
That would indicate that it is not set to high gain.
That would indicate that it is not set to high gain.
Thanks Zen Mod, I will try to start with 1 buffer first 🙂
I am thinking of ordering the B1 kit from PassDiy store. However, since I already have a passive pre-amp with remote controlled input switch selection and volume control, I would like to just continue to use it. Refferring to the schematic, would the circuit work as a standalone buffer without volume control (so that I can connect any other source equipment or passive pre-amp to its inputs) if I bypass R100, R101, P100, R200, R201, P200 and connect the input RCA with a straight wire directly to R102 and R202?
I am thinking of ordering the B1 kit from PassDiy store. However, since I already have a passive pre-amp with remote controlled input switch selection and volume control, I would like to just continue to use it. Refferring to the schematic, would the circuit work as a standalone buffer without volume control (so that I can connect any other source equipment or passive pre-amp to its inputs) if I bypass R100, R101, P100, R200, R201, P200 and connect the input RCA with a straight wire directly to R102 and R202?
Why not just build B-1 and use a selector switch instead of the two input toggle switch, and also add two outputs, one for F-5 and one for sub?
yes , you can
even if I didn't checked parts designation (not knowing on which exact iteration you're pointing) , but I believe you got it right
I have to admit that I am lazy, therefore would like to keep the passive pre-amp so that I can select the inputs and change the volume using the remote control. If the B1 circuit would still work being connected that way, that would be just great. ;-)
You need two things to happen.... one a global volume control and two, an independent volume control to match the subs to the main speakers. If you use buffers/passives,the independent control can only attenuate the signal that goes to the more sensitive amp.
Hopefully, that is ok from an overall volume perspective.
Hopefully, that is ok from an overall volume perspective.
Hi,
Driving long subwoofer cables from a power amp output
in parallel with the power amplifier is a recipe for trouble,
especially with a passive pre-amp it is likely to be poor.
The simplest buffer you can use is your power amplifier.
Attenuate its output to line level to drive the sub cable.
rgds, sreten.
Driving a sub from my Audiolab 8000a powerampout clearly
affected the top end due to driving the cable capacitance.
Another fix would be a series R in the drive to the sub.
Driving long subwoofer cables from a power amp output
in parallel with the power amplifier is a recipe for trouble,
especially with a passive pre-amp it is likely to be poor.
The simplest buffer you can use is your power amplifier.
Attenuate its output to line level to drive the sub cable.
rgds, sreten.
Driving a sub from my Audiolab 8000a powerampout clearly
affected the top end due to driving the cable capacitance.
Another fix would be a series R in the drive to the sub.
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@BigE, lucky for me, the two things you mentioned are available. I have the passive pre-amp as the global volume control. The passive pre-amp now has two line out (after I put a 1 to 2 splitter at its single line out) : one to the power amp, another to the sub. The sub has it's own gain level control. I have managed to match the level between the power amp to the mains and the sub by ear (hopefully that is accurate).
@sreten: yes, as I have experienced just now, it is really troublesome. The sub cable is long, and the low input impedence of the sub is not helping the situation. So I am going to try to put a buffer at the line output that goes to the sub, and leave the other line output that goes to the F5 as it is for the moment, hoping that the buffer would be able to drive the long cable and also handle the low input impedence of the sub.
@sreten: yes, as I have experienced just now, it is really troublesome. The sub cable is long, and the low input impedence of the sub is not helping the situation. So I am going to try to put a buffer at the line output that goes to the sub, and leave the other line output that goes to the F5 as it is for the moment, hoping that the buffer would be able to drive the long cable and also handle the low input impedence of the sub.
Hi,
If the sub has plenty of spare gain (input impedance is 15K) put
series resistors in its cable at the preamp end, say 10K. This
will cause a treble roll-off due to cable capacitance but that
won't matter, and it will prevent the capacitance loading.
rgds, sreten
If the sub has plenty of spare gain (input impedance is 15K) put
series resistors in its cable at the preamp end, say 10K. This
will cause a treble roll-off due to cable capacitance but that
won't matter, and it will prevent the capacitance loading.
rgds, sreten
Hi All,
So I have started building the B1 buffer by ordering for the parts and components required for the Pass B1 buffer. The version that I chose is the Passdiy version, and ordered the PCB+4 Matched JFETs from the passdiy website.
The problem I am facing now is I have ordered a capacitor (C101 and 201 in the original B1 article) that is too huge for the chasis: FP-CA-10-AU - AMPOHM WOUND PRODUCTS - CAP, FILM, PP, 10UF, 630V, AXIAL | element14 Malaysia
I only realised this when I started to stuff the PCB yesterday. So I am wondering whether using other types of capacitor will affect the sound very much, and whether this particular one will be OK to use: MKT1822610016 - VISHAY ROEDERSTEIN - CAP, FILM, PET, 10UF, 100V, RAD | element14 Malaysia
Best regards
Liu
So I have started building the B1 buffer by ordering for the parts and components required for the Pass B1 buffer. The version that I chose is the Passdiy version, and ordered the PCB+4 Matched JFETs from the passdiy website.
The problem I am facing now is I have ordered a capacitor (C101 and 201 in the original B1 article) that is too huge for the chasis: FP-CA-10-AU - AMPOHM WOUND PRODUCTS - CAP, FILM, PP, 10UF, 630V, AXIAL | element14 Malaysia
I only realised this when I started to stuff the PCB yesterday. So I am wondering whether using other types of capacitor will affect the sound very much, and whether this particular one will be OK to use: MKT1822610016 - VISHAY ROEDERSTEIN - CAP, FILM, PET, 10UF, 100V, RAD | element14 Malaysia
Best regards
Liu
If it is too long you can still use it by mounting it "standing soldier" style. Stick one end in the board with the cap vertical and bend the lead to insert the other end in the board. Attach a wire if necessary. I am using this capacitor.
RFS-35V100ME3#5 Elna | Mouser
I very good capacitor recommended by Mr Pass.
RFS-35V100ME3#5 Elna | Mouser
I very good capacitor recommended by Mr Pass.
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