That will get you ~35V rails, ideal for 8 ohms not so good for 4 ohms. The expedient thing to do is to build another identical anp and use 1 channel per driver.
dave
Totally agree which is why I did use 1 channel per driver. I only hooked one tower to the amp, one channel drove the top woofer, the other channel drove the bottom woofer. The second tower was being run by my sherwood amp for comparison purposes.
Could you advise me as to whether fitting large capacitors to my power supply would fix my gainclone running out of oomph? ATM it only has something like 10uF caps on each rail. A lot of other amp designs I've seen have huge caps on the power supply.
I remember reading somewhere that for a 4R load, 100uF per watt was recommended, most of my 100W nominal amps run 10,000uF smoothing caps
The PD chip amp had low capacitance because that gives it more delicacy in the mid/top. For use as a woofer amp more C is a good idea.
dave
dave
Dual woofers can be parallel or series to halve the excursion.
Extra capacitance isn't going to make a huge difference as ChipAmps aren't renowned as a power house or supply heaps of current. You need to go to a more heft SS design such as the SC amps.... eg Altronics K5151.
No as it doesn't work like that. It's not the DC on input but the balance within the circuit. Some work out fine but others (one I built) has DC offset from hell even with matching resistors. You can fine tune it with resistor values but a pain especially on double sided PCBs.
Run the 4 woofers in series - parallel and you end up with 8 ohm and 6dB efficiency gain over a single woofer.
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Thanks very much to everyone for their help. That clears up a great deal for me.
I think I'm getting turned off the idea of using a gainclone to power the woofers. It sounds fantastic paired with my bookshelf speakers (better than the sherwood imo).
@ rabbitz, I now understand what you are saying about dual woofers in one enclosure having ~half the excursion of a single woofer. In winISD, when I dropped the number of woofers from 2 to 1, the cone excursion doubled on the graph. I guess that's a benefit of having two woofers in one enclosure. Can't imagine that it would be good if one woofer simply stopped working, surely the remaining woofer would just let go of its cone? haha.
I also have another query which any of you will most likely be able to answer easily, slipped my mind earlier. Since trying to drive one of my woofer towers with the gainclone, one of the drivers has started making a disgusting noise. It's most likely a coincidence that it is also the same driver that had a slightly bent basket when it arrived. It's hard to explain, but it sounds like something is loose/moving inside the actual speaker. I'm half guessing that when my underpowered amp was struggling to cope, it was clipping and damaged the driver. I quickly reduced the volume as soon as the speakers started sounding strange. Funny thing is that the other appears to be fine and is making no strange noises when being driven hard from the original sherwood amp.
I think it's clear that I've damaged something, but is it possible to damage a speaker through clipping if it was only permitted to do so for a couple of seconds? Luckily a replacement is only ~$30.
I think I'm getting turned off the idea of using a gainclone to power the woofers. It sounds fantastic paired with my bookshelf speakers (better than the sherwood imo).
@ rabbitz, I now understand what you are saying about dual woofers in one enclosure having ~half the excursion of a single woofer. In winISD, when I dropped the number of woofers from 2 to 1, the cone excursion doubled on the graph. I guess that's a benefit of having two woofers in one enclosure. Can't imagine that it would be good if one woofer simply stopped working, surely the remaining woofer would just let go of its cone? haha.
I also have another query which any of you will most likely be able to answer easily, slipped my mind earlier. Since trying to drive one of my woofer towers with the gainclone, one of the drivers has started making a disgusting noise. It's most likely a coincidence that it is also the same driver that had a slightly bent basket when it arrived. It's hard to explain, but it sounds like something is loose/moving inside the actual speaker. I'm half guessing that when my underpowered amp was struggling to cope, it was clipping and damaged the driver. I quickly reduced the volume as soon as the speakers started sounding strange. Funny thing is that the other appears to be fine and is making no strange noises when being driven hard from the original sherwood amp.
I think it's clear that I've damaged something, but is it possible to damage a speaker through clipping if it was only permitted to do so for a couple of seconds? Luckily a replacement is only ~$30.
Just on this point.
Altronics - Your One Stop Audio Visual & Electronics Supplier
Altronics - Your One Stop Audio Visual & Electronics Supplier
Altronics - Your One Stop Audio Visual & Electronics Supplier
Other than the links above, I will need PSU capacitors and rectifiers.
If I decided to go down this route, how many amps would I need? I'm guessing that one would be cutting it slim, whilst two would probably be plenty. Biggest problem that I see going with two is that these amps are also designed for 8ohm loads. Could I essentially buy a transformer with lower voltage to keep the amp producing no more than 100W with my speakers paralleled? Basically the same idea with driving a 4ohm load with my gainclone. If one amp is enough, then I can simply run the woofers in series then parallel to result in a 8ohm load.
You really only need to run one amp (drivers series - parallel) as there is already a 6dB gain in efficiency, unless you want stereo subs then each side with 2 drivers in parallel giving a 4 ohm load. I built one of these SC 100W amps and can drive subs with ease unlike GainClones. The output devices used on these amps are more robust and can supply heaps of current and almost double their power when halving the impedance so rail voltages do not need to be lowered.
All you need is a heatsink (H0545), transformer rated to the spec in the build information (IIRC was around 35-42VAC 300VA), a bridge rectifier and some caps.... maybe around 30,000uF at 63VDC rating. They have a power supply K5153 for this amp.
A case, wiring, connectors are also required.
For the noisy driver, check when you push the driver in that the VC is not rubbing as if it bottomed out, the VC may be mushroomed (unlikely). A twisted pressed steel frame can also do this. Loose spider under the cone can also give this noise and is a common issue with some of the Peerless XLS drivers. I don't think you have damaged the VC and check the Re with a DMM. You can compare against the other drivers and should be around 5R5 to 6R5.
All you need is a heatsink (H0545), transformer rated to the spec in the build information (IIRC was around 35-42VAC 300VA), a bridge rectifier and some caps.... maybe around 30,000uF at 63VDC rating. They have a power supply K5153 for this amp.
A case, wiring, connectors are also required.
For the noisy driver, check when you push the driver in that the VC is not rubbing as if it bottomed out, the VC may be mushroomed (unlikely). A twisted pressed steel frame can also do this. Loose spider under the cone can also give this noise and is a common issue with some of the Peerless XLS drivers. I don't think you have damaged the VC and check the Re with a DMM. You can compare against the other drivers and should be around 5R5 to 6R5.
Thanks rabbitz, too easy.
I only have a mono feed for the sub coming from the PC, but if these amps can handle a 4 ohm load without needing to reduce the rail voltage, I'm just going to grab two now, they're on special as it is.
Thanks for the tips on the noisy driver, I'll give it a go.
Edit:
Just realised I was looking at the K5150, not the K5151. One amplifier will do for now I think...
I only have a mono feed for the sub coming from the PC, but if these amps can handle a 4 ohm load without needing to reduce the rail voltage, I'm just going to grab two now, they're on special as it is.
Thanks for the tips on the noisy driver, I'll give it a go.
Edit:
Just realised I was looking at the K5150, not the K5151. One amplifier will do for now I think...
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Damn, I just finished buying one... I guess you're starting to see how impulsive I am, haha.
Even still, I wouldn't mind having a couple sitting around. Do you have any like I used on my gainclone? They are roughly 200mm x 70mm x 45mm? Anything around that size : $10 each plus postage???
Even still, I wouldn't mind having a couple sitting around. Do you have any like I used on my gainclone? They are roughly 200mm x 70mm x 45mm? Anything around that size : $10 each plus postage???
Actually, the heat sinks are out of stock at altronics. So I'll still need one for this amp.
Let me know what you have and what you want for it (send a pm if you'd like). The recommend HS was around 300mmx45mmx70mm. I'm thinking that it's overkill for this application, especially considering I will only be using this with an 8ohm load. I'm guessing I'd make do with a single 200mm heatsink, was even considering chucking a spare pc case fan in the enclosure anyway.
Let me know what you have and what you want for it (send a pm if you'd like). The recommend HS was around 300mmx45mmx70mm. I'm thinking that it's overkill for this application, especially considering I will only be using this with an 8ohm load. I'm guessing I'd make do with a single 200mm heatsink, was even considering chucking a spare pc case fan in the enclosure anyway.
Can you post a link to the kit you will be building
i have some BNIB heatsinks here but they cost me about $40- each, but i have quite a few salvaged ones which (of course ) are much more likely to be in your price range
i have some BNIB heatsinks here but they cost me about $40- each, but i have quite a few salvaged ones which (of course ) are much more likely to be in your price range
ROCKBY SPECIALS PAGE 3
HUGE
68000uF but only 63V
$35 each nothing like overkill on the storage/smoothing
HUGE
68000uF but only 63V
$35 each nothing like overkill on the storage/smoothing
Wow, that's big.
Caps will be the next thing you'll see a tonne of queries for in this thread, haha. I'm going to wait until I have the kit in my hands though, see what I'm up against.
Caps will be the next thing you'll see a tonne of queries for in this thread, haha. I'm going to wait until I have the kit in my hands though, see what I'm up against.
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