Oh well, on what forum to post a question on an amplifier for a subwoofer? My question is somewhat elaborate because it refers to the various choices to be made, and to experiences from others.
In the German magazine HobbyHifi of April/May 2013 a subwoofer was presented with the Mivoc XAW320HC (220W RMS/600W/4 ohm) and an identical passive membram XAW320PR. Back then, I bought the woofer set, but did not yet buy an amplifier module. What amplifier for a subwoofer, that is my question now.
In the same issue of the magazine, the German subwoofer plate amplifier Detonation DT-300 was described: 210W/8 ohm in ClassD with ample filter options in a closed box seemed adequate. However, on various German fora this plate amplifier appeared to have issues, and the service of the manufacturer was lacking. In the past years, the technology and the market for subwoofer amplifiers have developed fast. For instance, the most recent issue of HobbyHiFi of august/September is fully focused on the theme of the subwoofer. See the following link:
HOBBY HiFi
HOBBY HiFi 1/03
More specific, the following amplifier modules are reviewed in this HobbyHiFi-magazine:
Audaphon, AMP-24-4250: 2x or 4x 500W/4 ohm; DSP filter; XLR/Cinch; USB; plate
Mini-DSP & Ice-Power, PWR-ICE125: 2x 125W/4 ohm, or 1x 450W/4ohm; DSP filter; XLR (analog + AES/EBU)/cinch; Ethernet RJ45; plate
Monacor, AKB-400 DSP: 1x 400W/4 ohm; 2x DSP filter; XLR; USB; plate
McCrypt, PAC15A: 1x 200W/4 ohm; simple analog filter; XLR/6,3 jack; - ; plate
Reckhorn A-409: 1x 365W/2 ohm in analogue design; elaborate analog filter; cinch; - ; box
The price range is between € 115 (McCrypt), € 300-350 (Monacor, Reckhorn, and Mini-DSP & Ice-Power) up to € 600/750 (Audaphon). What strikes is that even in this small selection not all are specifically designed for subwoofer use.
For diy’ers quite some links for a subwoofer amplifier come to mind, of which many on our diyaudio forum. Some mention a gainclone amplifier in parallel would do a good job. Moreover, there are threads as the Honey Badger, which offer a solid amplifier and power supply of classic design:
http://www.diyaudio.com/forums/solid-state/211905-diyab-amp-honey-badger-build-thread-125.html
In ClassD several threads explicitely mention the application for a subwoofer, such as:
www.diyaudio.com/forums/class-d/294294-class-d-bass-amps-best-recommendations.html#post4775238
or
http://www.diyaudio.com/forums/vendors-bazaar/238156-amplifier-modules-pcbs-sale-24.html
In the diy approach for a subwoofer, in addition to an amplifier, a separate analog or DSP filter is required, and also here are several serious threads to be found. A diy solution has the advantage of being able to repair or upgrade.
So, what criteria are relevant to decide whether to buy or to diy? The classical analog approach offers a reliable solution. My first subwoofer is still in silent service: the ‘roaring subwoofer’ of Russel Breden in Electronics World of February 1997. You really want a subwoofer amplifier to be reliable first and for all. What strikes from an internet search is the significant number of times a ClassD amp, as well as a switched power supply (SMPS), is mentioned to have problems after some time of use.
What is wise, a ClassB or ClassD design? In ClassD the so called half bridge seems to require attention for the power supply, in order to not be confronted with increasing supply voltage and an activating protection. See, for instance:
www.diyaudio.com/forums/class-d/281698-abletec-53v-dual-rail-450w-supply-20-a-10.html
Is full bridge the way to go for a ClassD subwoofer application? Furthermore, the power supply needs to be adequate, and SMPS or analog do not seem to differentiate much (analog being more bulky). The specs for readily available SMPS devices are hard to read for an average diy’er like me, though.
As for the filter, nowadays DSP is available in different kinds and easy to use. However, a well designed analog filter is hard to beat, and at least has no latency issues.
Such variety in options make it difficult to choose.
Can you please share you experience from practice with a subwoofer amplifier, and it's power supply?
In the German magazine HobbyHifi of April/May 2013 a subwoofer was presented with the Mivoc XAW320HC (220W RMS/600W/4 ohm) and an identical passive membram XAW320PR. Back then, I bought the woofer set, but did not yet buy an amplifier module. What amplifier for a subwoofer, that is my question now.
In the same issue of the magazine, the German subwoofer plate amplifier Detonation DT-300 was described: 210W/8 ohm in ClassD with ample filter options in a closed box seemed adequate. However, on various German fora this plate amplifier appeared to have issues, and the service of the manufacturer was lacking. In the past years, the technology and the market for subwoofer amplifiers have developed fast. For instance, the most recent issue of HobbyHiFi of august/September is fully focused on the theme of the subwoofer. See the following link:
HOBBY HiFi
HOBBY HiFi 1/03
More specific, the following amplifier modules are reviewed in this HobbyHiFi-magazine:
Audaphon, AMP-24-4250: 2x or 4x 500W/4 ohm; DSP filter; XLR/Cinch; USB; plate
Mini-DSP & Ice-Power, PWR-ICE125: 2x 125W/4 ohm, or 1x 450W/4ohm; DSP filter; XLR (analog + AES/EBU)/cinch; Ethernet RJ45; plate
Monacor, AKB-400 DSP: 1x 400W/4 ohm; 2x DSP filter; XLR; USB; plate
McCrypt, PAC15A: 1x 200W/4 ohm; simple analog filter; XLR/6,3 jack; - ; plate
Reckhorn A-409: 1x 365W/2 ohm in analogue design; elaborate analog filter; cinch; - ; box
The price range is between € 115 (McCrypt), € 300-350 (Monacor, Reckhorn, and Mini-DSP & Ice-Power) up to € 600/750 (Audaphon). What strikes is that even in this small selection not all are specifically designed for subwoofer use.
For diy’ers quite some links for a subwoofer amplifier come to mind, of which many on our diyaudio forum. Some mention a gainclone amplifier in parallel would do a good job. Moreover, there are threads as the Honey Badger, which offer a solid amplifier and power supply of classic design:
http://www.diyaudio.com/forums/solid-state/211905-diyab-amp-honey-badger-build-thread-125.html
In ClassD several threads explicitely mention the application for a subwoofer, such as:
www.diyaudio.com/forums/class-d/294294-class-d-bass-amps-best-recommendations.html#post4775238
or
http://www.diyaudio.com/forums/vendors-bazaar/238156-amplifier-modules-pcbs-sale-24.html
In the diy approach for a subwoofer, in addition to an amplifier, a separate analog or DSP filter is required, and also here are several serious threads to be found. A diy solution has the advantage of being able to repair or upgrade.
So, what criteria are relevant to decide whether to buy or to diy? The classical analog approach offers a reliable solution. My first subwoofer is still in silent service: the ‘roaring subwoofer’ of Russel Breden in Electronics World of February 1997. You really want a subwoofer amplifier to be reliable first and for all. What strikes from an internet search is the significant number of times a ClassD amp, as well as a switched power supply (SMPS), is mentioned to have problems after some time of use.
What is wise, a ClassB or ClassD design? In ClassD the so called half bridge seems to require attention for the power supply, in order to not be confronted with increasing supply voltage and an activating protection. See, for instance:
www.diyaudio.com/forums/class-d/281698-abletec-53v-dual-rail-450w-supply-20-a-10.html
Is full bridge the way to go for a ClassD subwoofer application? Furthermore, the power supply needs to be adequate, and SMPS or analog do not seem to differentiate much (analog being more bulky). The specs for readily available SMPS devices are hard to read for an average diy’er like me, though.
As for the filter, nowadays DSP is available in different kinds and easy to use. However, a well designed analog filter is hard to beat, and at least has no latency issues.
Such variety in options make it difficult to choose.
Can you please share you experience from practice with a subwoofer amplifier, and it's power supply?
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The power amplifier needs a good PSU. That's where most kits, or pre-made, will fall down.
It needs the LF time constants set to allow ALL of the bottom two octaves from 20Hz to 80Hz to pass through without any attenuation on sustained bass notes.
And finally it must be capable of supplying current when the speaker demands current.
A good clue to this last is the maximum power specification into rated load and then into half the rated load.
eg.
from a Yamaha
80W x 2 into 8ohms both channels driven
105W x 2 into 4ohms both channels driven
90W in 8ohms one channel driven
120W into 4ohms one channel driven
The increase when one channel is driven gives an indication that the PSU is near it's limit for current delivery when both channels are driving 4ohms.
The small increase from 8ohms to 4ohms tells us that the amplifier cannot deliver adequate current into a 4ohms load.
This amplifier will perform better as a 90W into 8ohms bass amp with one channel disabled. Except that the low end response is stated as 10Hz. No clue is given whether that is F-3db, or F-1db. But in either case it is too high for a bass amplifier. You should probably be looking for F-3dB lower than 4Hz and maybe lower than 2Hz, giving an F-1dB ~2Hz
It needs the LF time constants set to allow ALL of the bottom two octaves from 20Hz to 80Hz to pass through without any attenuation on sustained bass notes.
And finally it must be capable of supplying current when the speaker demands current.
A good clue to this last is the maximum power specification into rated load and then into half the rated load.
eg.
from a Yamaha
80W x 2 into 8ohms both channels driven
105W x 2 into 4ohms both channels driven
90W in 8ohms one channel driven
120W into 4ohms one channel driven
The increase when one channel is driven gives an indication that the PSU is near it's limit for current delivery when both channels are driving 4ohms.
The small increase from 8ohms to 4ohms tells us that the amplifier cannot deliver adequate current into a 4ohms load.
This amplifier will perform better as a 90W into 8ohms bass amp with one channel disabled. Except that the low end response is stated as 10Hz. No clue is given whether that is F-3db, or F-1db. But in either case it is too high for a bass amplifier. You should probably be looking for F-3dB lower than 4Hz and maybe lower than 2Hz, giving an F-1dB ~2Hz
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Andrew,
I'm afraid I have to disagree about LF rolloffs. I haven't seen many systems online that'll reach down to 4Hz with authority. One of them was a wall of those Peerless 12" subs in a concrete basement. Another was a lot of 18"s and 21"s and of the order of 40KW in amplification.
Most systems, even the serious ones, stop before 10Hz.
Chris
I'm afraid I have to disagree about LF rolloffs. I haven't seen many systems online that'll reach down to 4Hz with authority. One of them was a wall of those Peerless 12" subs in a concrete basement. Another was a lot of 18"s and 21"s and of the order of 40KW in amplification.
Most systems, even the serious ones, stop before 10Hz.
Chris
If you are aiming for PA duty, then LF roll-off has to be done much higher to protect the Drivers from damage.
For domestic type reproduction you need the amplifier to pass ALL the audio LF band.
For domestic type reproduction you need the amplifier to pass ALL the audio LF band.
I'd agree on PA systems. That's a given.
For home audio, 99.99999...% of systems will be just fine with a 10Hz cutoff, since they simply don't have the speakers that can reproduce frequencies down that low. All you'll get is distortion, so I actually think its beneficial to roll off below even 20Hz, unless you know your system can handle it.
Chris
For home audio, 99.99999...% of systems will be just fine with a 10Hz cutoff, since they simply don't have the speakers that can reproduce frequencies down that low. All you'll get is distortion, so I actually think its beneficial to roll off below even 20Hz, unless you know your system can handle it.
Chris
hi ... i've used ready made TDA8950 class D kit for subwoofer duty in BTL mode into 4ohms ... so far didnt face any issue yet ... would like to hear from your opinnion too
Thanks for responding; an interesting start of the thread.
@Dannyjmf: you write about a kit. Was the power supply already in the kit?
Can you please elaborate?
@Dannyjmf: you write about a kit. Was the power supply already in the kit?
Can you please elaborate?
My experience culminated in tossing out Class D and using 2 pairs of VMOS driven by a LME49830. I chose the smaller IRFP640/9640 devices as HF performance was not needed and their input capacitance would not be a problem. They run 42V rails, biased at 50mA per pair.
I find this has better transient capability and a cleaner bass. The Class D IRS2092 theoretically performs just as well, but in real life it really didn't. The bass was a little spongy and not totally clean.
I find this has better transient capability and a cleaner bass. The Class D IRS2092 theoretically performs just as well, but in real life it really didn't. The bass was a little spongy and not totally clean.
I think the comments above on power supply are relevant. You want a power supply that can supply lots of current for relatively long periods. Most SMPS's cannot deliver large transient currents, except those that allow you to hang a large electrolyic (10,000uF + ) on their output to take up the lf transients. Not all SMPS's allow that, so that's something to look for.
Other than that I believe an SMPS is a good solution.
As to the amp, I would go for class D. Sometimes they sound different than AB but in my experience that is because AB just doesn't cut it at those levels and frequencies. Bridge or not would not be a point for me, but more the power into 4 ohms (if that it your requirement). Not the peak power but the average or RMS power!
Jan
Other than that I believe an SMPS is a good solution.
As to the amp, I would go for class D. Sometimes they sound different than AB but in my experience that is because AB just doesn't cut it at those levels and frequencies. Bridge or not would not be a point for me, but more the power into 4 ohms (if that it your requirement). Not the peak power but the average or RMS power!
Jan
Hi,
I´m totally confident with powersoft class-D modules.
Most of them come with PSU (and PFC) included and they are true professional products in every respect.
Some even come with a DSP-filter integrated or a slot for their proprietry DSP modules.
They may not be the cheapest modules, but they are extremely compact, span a wide power range (from 100W to several kW) and are very reliable.
I never had any issues so far.
Sonically they perform with very tight controlled and powerful sound.
jauu
Calvin
I´m totally confident with powersoft class-D modules.
Most of them come with PSU (and PFC) included and they are true professional products in every respect.
Some even come with a DSP-filter integrated or a slot for their proprietry DSP modules.
They may not be the cheapest modules, but they are extremely compact, span a wide power range (from 100W to several kW) and are very reliable.
I never had any issues so far.
Sonically they perform with very tight controlled and powerful sound.
jauu
Calvin
Yup .. The power supply is built in the kit already ... there is a photo shown below ...
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