Hi Mike,
Thanks for taking time to draw this out.
I would like to understand what causes the improvement in sound. What is the logic behind this - crosstalk, voltage drop across channels on power surge, etc?
If I know the factors involved I can knowingly decide which approach to take for my design - 1 chassis, 2 chassis, 4 chassis or 6 chassis. Else it is just following someones recommendation without knowing the rational, hope you understand.
Regards
It's not really a matter of improving sound per se, rather the avoidance of degrading sound quality. Due to the way the sound spectrum is generally apportioned, the woofers and mid range drivers will draw the most current from the amps, and the tweeters much less. So it makes sense to put the two woofer amps together in one box with a single power supply (both amps will be passing identical signals so they won't interfere with each other), and the mid and tweeter amps in another box sharing a single power supply (tweeter amps won't have much current draw and generally won't have as high of a signal level, so there won't be any problem sharing a power supply with the mid amp). And as I already stated, dividing amps into several boxes will make construction and troubleshooting easier. Keep in mind that the more complex something is, it's more likely there will be problems, and more difficult to work with. Another factor to consider is cost. Generally the boxes, heatsinks and hardware will be the most expensive items, followed by power supply components, and lastly the electronics.
Mike
Mike
I originally powered my Orions with two 4 channel amps rated at 60 WPC & in this configuration the woofers were driven by 1 channel each. In this configuration it was possible to get clipping of the woofer channels although it required very bass-heavy program material and at listening levels much higher than I would typically use. The move to 100 WPC on the woofers eliminated this issue for me and the overall sound quality was improved.
There is no change to the ASP required but you must carefully balance the gain of each amplifier channel (single or bridged), so your amp should include a gain adjustment pot. I do this by starting with a tone at the W-M crossover frequency into the ASP and adjusting the gain of each woofer and midrange channel for an output voltage that corresponds to a gain of 26dB (SL's recommended level) with a tolerance of +/- 0.1dB. Once these are set move to a tone at the M-T crossover frequency and match the gain of the tweeter amps to the same gain value as the midrange without changing the previously set midrange gain! For this you will need a stable tone generator (I use a modified Heathkit IG18) and a good multimeter preferably with 4 1/2 digits and frequency and true RMS voltage measurement (I use a BK Precision 2834).
Finally before you dive in you may want to consider buying an amp
(I know - heresy on a DIY forum). Similar to the ATI amp that SL recommends the Sonance 1250MKII amp I bought retails for $1700 new. But they regularly show up on eBay and Audiogon (unlike the ATI 1260) and the winning bid is typically around $500 (I paid $525). I suspect you will have a tough time keeping your parts expenditure under this level (chassis & heat sinks are the big hitter) and, as many others have commented, this is a huge undertaking for a 1st DIY build. Either way good luck...it will be worth the journey!Thanks Kevin, this is one of the most helpful information.
I thought that 50-60w would be inadequate for the woofer channel, but you have confirmed the same.
Finally before you dive in you may want to consider buying an amp
Frankly speaking DIY process of building something in itself is great fun, learning and satisfying experience.
Plus, I would like to build an amp that by itself is better than an ATI or Sonance or any other commercial amp costing 5 times more
The amp budget is $1000 to $1500, depending on what configuration I take. I believe that is a lot of money to build a high quality chip amp!
I am a hardcore DIYer and have done many complex projects in my first attempt (though not in this space), so I am determined and confident enough to pull it off.
I have been reading up on this on forums and have got mixed opinions.
The positives of a separate power supply, seems to be...
+ Freedom from interconnected Audio Grounds (what does this mean???)
+ Less Crosstalk between channels - more stereo seperation leading to better imaging and depth
+ Don’t fight with other channel during intense musical passages, specially for low frequency
+ Provides greater dynamic range
+ Shorter speaker wire (but longer interconnects - they need to be balanced)
+ More audiophile gadget appeal - means highend serious business
Negatives being...
- More expensive - cost of extra chasis, transformer, rectifiers, etc
- Grounding issues
- More space requirement to house the extra chassis
- More weight
Where as Douglas Self, who is a good authority on Audio Amplifiers has following to share
The above leads me to believe the following in order of increasing expense and diminishing returns...
1. Common PSU (Power supply unit)
2. Separation of left vs right channel PSU
3. Separation of woofer PSU from Tweeter and Midrange PSU (as suggested by Mike)
4. Separation of all channels PSU on all sides (as suggested by Andrew)
The first thing you should do is to buy the Orion construction kit. It contains all the information you need to build the speaker and the cross-over plus the PCB for the latter.
The tweeter is a 6 Ohm model and paralleling them brings the impedance down to 3 Ohm. The woofers are 4 Ohm models and quite current hungry due to their high moving mass. There is a reason why Linkwitz himself recommends solid state amps for the task.
If you still want to try it with chip amps, follow Andrew's advice and build a mono- or stereo amp first. If you succeed, you can add more channels by Copy-&-Paste. If you don't, you cut your losses.
The tweeter is a 6 Ohm model and paralleling them brings the impedance down to 3 Ohm. The woofers are 4 Ohm models and quite current hungry due to their high moving mass. There is a reason why Linkwitz himself recommends solid state amps for the task.
If you still want to try it with chip amps, follow Andrew's advice and build a mono- or stereo amp first. If you succeed, you can add more channels by Copy-&-Paste. If you don't, you cut your losses.
Hi Pacificblue,
That is already agreed based on suggestions from Andrew and Mike, I will make 1 mono channel first, experiment with it and fine tune the circuit before building rest of the amps. Makes perfect sense.
But I still need to decide on the over all amp design and configuration. Building one channel will still not allow me to decide on those aspects - like single PSU or multiple one, how many chassis, etc.
Tweeter is 6 ohm but on the frequency range it operates on it dips down to 5 ohm (speaker has variable impedance based on the frequency).
Woofers are Peerless 830452 and each one is 8 ohm impedance. I am building Orion 3.3 ver.
Though I have not bought the Orion construction plan yet, but I have gone through the whole site to understand the project. With Construction plan, it should be a simple project to build. Moreover, Linkwitz doesn't provide any additional information on amplifier design in that plan. All amplifier requirements are mentioned in his public webpages and FAQ section.
Thanks,
ST7677,
I am a pretty accomplished woodworker and have done a fair bit of electronics DIY and I would describe Orion as a straightforward but hardly simple project. A lot depends on how basic or exotic your choices are in materials, details and finishes on the cabinets. If you are going for painted MDF that helps alot but if your tastes are more toward solid woods with inlays, etc that's a lot tougher - and more fun! The ASP is simple enough to assemble but you will encounter some challenges in finding all of the tight tolerance film caps as that is an area of ongoing flux. Overall though your planned amp project is likely a good bit tougher than the speaker system.
Hi Kevin,
Planning to use plyboard wood for the orion construction.
I have not decided on the final finish, but most likely it will be mix of clear lacquered Veneer with inlays, and duco paint (automotive finish).
I hear that with (latest DIY) 3.3version upgrade Linkwitz has revised the ASP components list to what is available today (as many of the earlier parts list were not available any more).
New Orion ASP PCB boards are also expected this month which are slightly simpler to assemble and offer more options.
With the circuit diagram, construction plan and PCB boards directly from Linkwitz and support from Orion forum, I am pretty comfortable with the Orion. I am only worried about the amps. I want pretty much the best that can be done with LM3886s
PS: Wishing happy independence day to all Indian
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My calculations suggests that in dipole configuration
The woofer driven from 50W amplifier and 7 amp max current will be
XMAX limted at 20 hz
Voltage limited between 20hz to 88hz
Current limited above 88hz
Max freespace SPL at 30hz = 76db
Max freespace SPL at 90hz = 93db
The woofer driven from 130W amplifier and 12 amp max current will be
XMAX limted at 30 hz
Voltage limited above 30hz
Max freespace SPL at 30hz = 80db
Max freespace SPL at 90hz = 98db
Since the woofer is required to work between primarily between 20hz to 92 hz (later being the crossover cutoff to midrange) the second option seems to be the desired configuration.
Ofcourse these are for one woofer in open space. For 4 woofers in a room powered by individual amps, 18db can be added for overall loudness.
FWIW, the manufacturer of the active speaker I'm currently using recommends an overall headroom of 26dB above normal listening levels to accommodate peaks in orchestral music.
Normal listening levels will vary, of course, and can be 1/4 watt or less.
Another bit of useful info (from Rod Elliot's site) which may be of interest - a passive crossover loses around 3dB. So using 2 x 50 watt amps with a 2-way active speaker will match the output of the passive version driven by a single 200 watt amplifier.
Good luck with the project - you're getting some invaluable advice from the other posters here.
Normal listening levels will vary, of course, and can be 1/4 watt or less.
Another bit of useful info (from Rod Elliot's site) which may be of interest - a passive crossover loses around 3dB. So using 2 x 50 watt amps with a 2-way active speaker will match the output of the passive version driven by a single 200 watt amplifier.
Good luck with the project - you're getting some invaluable advice from the other posters here.
No I am planning to use the Peerless 830452 and build ver 3.3
In the version 3.4 SL has updated per channel power requirement to 150W, i.e. 150W x 8 channels of active amplification...
I generally aim for 20dB of headroom for AC peak to AC average dynamic range.
I regularly use low dynamic range sources (FM radio) that, even at maximum volume, cannot drive the chipamp to clipping.
Yet, from my normal listening levels of <680mW into 8ohm speakers, I can hear deterioration of SQ as average levels approach and go above ~1W into 8ohms, even though I know I am well below voltage clipping of the chipamp.
Since these are going to be DIY amplifiers and DIY speakers, I am planning to integrate the amplifiers into the speaker cabinate itself for increased WAF i.e. to reduce the space the whole thing will take, + reduction in number of cables for power and interconnection (Only two wires will go into a speaker (+amp) cabinate – one mains power and one source signal wire (RCA)).
The amplifiers and power supply will be separated and put on two different levels respectively (see image).
The amplifiers (8 LM3886s) will be housed in the bottom most part of each speaker cabinate (this is in an extended height area over standard design).
The power supply will be put between the mid range and the woofer speakers, where about 5-6" space is already available.
Most wires will move within the cabinate, ie. power wires between the Power Supply to ASP / Amplifiers and signal wired between ASP to Amplifiers and then to speakers.
IMO, There are multiple advantages to this approach.
1. Separation of power supply and amplifiers, reducing induction related noises and cleaner sound
2. Short wiring between amplifier and speaker, which means less expense on speaker wires and better amplifier control on speaker (damping effect, due to lower wire resistance).
3. Integrated design, saves space in my small house
4. Clean wiring - only 2 wires will go to each speaker. Else wires will first go to ASP from there 3 wires will go to amplifier from where 5 wires will go to speaker box + power wires to ASP and to Amps
5. No cost of expensive amplifier cases
Disadvantages are
1. All speakers (specially Tweeter and mid range) height moves up by about 5". As per standard Orion design Tweeter should ideally be at 42.5" i.e ear height level while sitting or slightly higher - is this a big issue over 8'+ listening distance
2. Rear wave of mid range may be slightly impacted due to additional box of amp power supply - again is this likely to be significant?
Any other possible issues?
Is there any possibility of amplifier power supply (torroids) interfereing with the speakers (mid range above and woofer below) in anyway (assuming I will keep the signal wires away from power wires)? There are likely to be two 500VA torroids placed together for each side of speaker.
Please share your inputs.
The amplifiers and power supply will be separated and put on two different levels respectively (see image).
The amplifiers (8 LM3886s) will be housed in the bottom most part of each speaker cabinate (this is in an extended height area over standard design).
The power supply will be put between the mid range and the woofer speakers, where about 5-6" space is already available.
Most wires will move within the cabinate, ie. power wires between the Power Supply to ASP / Amplifiers and signal wired between ASP to Amplifiers and then to speakers.
IMO, There are multiple advantages to this approach.
1. Separation of power supply and amplifiers, reducing induction related noises and cleaner sound
2. Short wiring between amplifier and speaker, which means less expense on speaker wires and better amplifier control on speaker (damping effect, due to lower wire resistance).
3. Integrated design, saves space in my small house
4. Clean wiring - only 2 wires will go to each speaker. Else wires will first go to ASP from there 3 wires will go to amplifier from where 5 wires will go to speaker box + power wires to ASP and to Amps
5. No cost of expensive amplifier cases
Disadvantages are
1. All speakers (specially Tweeter and mid range) height moves up by about 5". As per standard Orion design Tweeter should ideally be at 42.5" i.e ear height level while sitting or slightly higher - is this a big issue over 8'+ listening distance
2. Rear wave of mid range may be slightly impacted due to additional box of amp power supply - again is this likely to be significant?
Any other possible issues?
Is there any possibility of amplifier power supply (torroids) interfereing with the speakers (mid range above and woofer below) in anyway (assuming I will keep the signal wires away from power wires)? There are likely to be two 500VA torroids placed together for each side of speaker.
Please share your inputs.
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