It's an active system. The total power consumption of the 3 power amps on each channel will not be 3x the bass power. 350 VA seems reasonable . Per channel of course. This is a very good amp. Even if you can tweak it to get higher bias current, I think it's not worth it meddling with it. It sounds very good as is ! However for the sake of safety it will be better to use a relay protection at the output just in case something goes wrong. Murphy is ALWAYS lurking around the corner !
Use one relay protection circuit with all 3 channels connected to it with 3 separate resistors and 3 separate relays in parallel ( or series ....depends on coil voltage !). It will of course cut off all drivers if say the tweeter amp has gone bad. But then you won't be using the system with one driver not working !
Use one relay protection circuit with all 3 channels connected to it with 3 separate resistors and 3 separate relays in parallel ( or series ....depends on coil voltage !). It will of course cut off all drivers if say the tweeter amp has gone bad. But then you won't be using the system with one driver not working !
Thanks Ashok, yes 350VA per channel. The other idea i had was to use 2 modules and classD for the bass ..but the xover point is around 750hz. I have found in the past it's best to use the same amps from a synergy perspective, always sounds more cohesive, but it would be nice to have more than 120w for the bass, preferably double.
I'm hearing you on the speaker protection, worthwhile doing..
I'm hearing you on the speaker protection, worthwhile doing..
I seriously doubt you will have any issues using a classD with your bass driver even if it crosses at 750 Hz. Might even be a better system than the ss amp provided the classD is a good amp. Not all classD's sound great. I have several classD kits and some sound very good. Maybe one should say that many classD amps have a classD sound and some classD amps have "superb sound". There IS a 'slight' difference in the way we can class them ! 
Don't shy away from them.
Don't shy away from them.
I only have kits from 41Hz.com and a couple from eBay based on the IRF application manual. I felt the 41Hz kits sounded nicer. One kit is still unfinished !
Was stopped as a chip has to be soldered to the board using an oven ! The heat sink pad was to be soldered and I was trying to see if there was anyway around it ! I'm not confident of doing it with an oven without destroying the chip.
I also have a pair of Hypex UcD 400 units that have as yet not been turned on. They are already 5 years old ! Wonder if they will work !
Chinese IRF based classD 's work well especially for a sub. There are newer designs that I would like to try out. Not just yet as I have no time. I feel that one should always buy a kit with relay protection or install one yourself. Cannot afford to destroy an expensive driver if something goes wrong ! Apart from the cost it will also be the hassle of getting a replacement.
As far as ready made amps go, I bought a SMSL 50+50 watt classD recently. Sounds great. I love it ! Bought two of them eventually ! Nice over the whole bandwidth and inexpensive ! Very nice. I have a large Behringer iNuke classD also. Much more power but doesn't sound as good ! Maybe I should pull it out and try it again !
The one thing that's in extremely short supply is "time" !
Was stopped as a chip has to be soldered to the board using an oven ! The heat sink pad was to be soldered and I was trying to see if there was anyway around it ! I'm not confident of doing it with an oven without destroying the chip.
I also have a pair of Hypex UcD 400 units that have as yet not been turned on. They are already 5 years old ! Wonder if they will work !
Chinese IRF based classD 's work well especially for a sub. There are newer designs that I would like to try out. Not just yet as I have no time. I feel that one should always buy a kit with relay protection or install one yourself. Cannot afford to destroy an expensive driver if something goes wrong ! Apart from the cost it will also be the hassle of getting a replacement.
As far as ready made amps go, I bought a SMSL 50+50 watt classD recently. Sounds great. I love it ! Bought two of them eventually ! Nice over the whole bandwidth and inexpensive ! Very nice. I have a large Behringer iNuke classD also. Much more power but doesn't sound as good ! Maybe I should pull it out and try it again !
The one thing that's in extremely short supply is "time" !
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There are a lot of IRS2092 based classD on eBay. I have a couple of them. One is a stereo amp and the other is a subwoofer amp. Will be testing them again sometime soon.
I might get this one soon.
http://www.ebay.com/itm/Kit-IRS2092...448?pt=LH_DefaultDomain_0&hash=item2c9096b748
I might get this one soon.
http://www.ebay.com/itm/Kit-IRS2092...448?pt=LH_DefaultDomain_0&hash=item2c9096b748
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This is my design L15D-PRO. Digital amplifier.
From the installation process, L15D-PRO is convenient, simple, can save time.
From the performance, the L12-2 simulation and is more excellent.
Hi all I have read and re-read this thread with great interest.
I like to pretend that I understand all of the technical bits but sadly I don't!
that has not stopped me enjoying the discussions.
I am currently using a TPA-3116 amp board with a Stereo Coffee LDR to power a pair Proac Response 2.5 clones that I built many years ago.
Can any one advise me if the stock L12-2 or indeed the stock L15D-Pro would be a an improvement in sound quality over The TPA3116? With regards to the Stereo Coffee LDR how easy would it be to change (higher) the L12-2 input impedance for a better match.
Looking forward to any advice.
I like to pretend that I understand all of the technical bits but sadly I don't!
that has not stopped me enjoying the discussions.
I am currently using a TPA-3116 amp board with a Stereo Coffee LDR to power a pair Proac Response 2.5 clones that I built many years ago.
Can any one advise me if the stock L12-2 or indeed the stock L15D-Pro would be a an improvement in sound quality over The TPA3116? With regards to the Stereo Coffee LDR how easy would it be to change (higher) the L12-2 input impedance for a better match.
Looking forward to any advice.
I haven't found a spec. for the output impedance of Hifi Wigwam's LDR volume control kits but note that a match should not be necessary. All you need is higher impedance than the source to minimize loading. Most commercial preamps are ~ 200R output impedance and solid state amplifiers are between 10k and 50k input impedance, so there is no attempt to match impedance. The L12-2 is around 50k so it's at the high impedance end of the range. Most class D TPA3116 kits are specified at 22k.
Sound quality is in the ear of the beholder but I think traditional opinion would say the L12 will outclass any class D amplifier and other Ebay AB class kit amps too. It's an unusually fine sounding, higher powered amp kit, as others have posted here previously. If fitted, the Sanken output transistors for example, are about the best quality available at any price.
I guess you are aware that setting up a quality stereo amplifier is a lot bigger and more expensive project than a mini-D class amplifier. Check the rest of this thread out for clues.
Thank you Ian for your response.
An email from Chris (Stereo coffee)..."Recommended is a source component with low impedance capability, and power amps 50k or higher, or exceptions like Quad 306 that is 30k but has sensitive front end."
So the L12-2 should be just fine in that regard.
I have enjoyed tinkering with the smaller class D and class T amps, I built an Autocostruire 2020-m from a kit, and a hard wired inverted LM3875 some years ago. The TPA3116 I use currently has been the best of these, but I realise my speakers need something a bit better with better control.
I think the L12-2 sounds like it could be a step in the right direction, and for such a low price for the boards is a no brainer.
I will read through this thread again and garner as much info as I can, and hopefully practical advice will be available should I need it.
Thanks once again.
Ian
An email from Chris (Stereo coffee)..."Recommended is a source component with low impedance capability, and power amps 50k or higher, or exceptions like Quad 306 that is 30k but has sensitive front end."
So the L12-2 should be just fine in that regard.
I have enjoyed tinkering with the smaller class D and class T amps, I built an Autocostruire 2020-m from a kit, and a hard wired inverted LM3875 some years ago. The TPA3116 I use currently has been the best of these, but I realise my speakers need something a bit better with better control.
I think the L12-2 sounds like it could be a step in the right direction, and for such a low price for the boards is a no brainer.
I will read through this thread again and garner as much info as I can, and hopefully practical advice will be available should I need it.
Thanks once again.
Ian
Since my source is dc free ( has an output capacitor) I use my L12 without any input capacitor. It certainly sounds better in the bass ( deep,clean and taut ) without a generic cap. A good quality polyprop cap might be good but too big to fit on the board. But the stock electrolytic used there isn't too bad....just that it isn't as good as no cap !
BUT , IF you use no cap at the input , you need to be very careful. Any accidental connection to something with dc will fry your speakers without any speaker protection relay. The input could also be damaged if the dc voltage is high like a tube preamp without a coupling cap !
Might be a better idea to try out various caps at the input and pick what you think sounds best. That way you don't give the amp a chance to start 'smoking'. " Smoking kills" !
Note: the input impedance is a 100K parallel 11K. That works out to 9.91K ! The 11K is 1K in series and 10 K at the actual input of the circuit. You can raise the 10 K to 22k or 47K. This will increase the dc offset at the output of the amp for which there is no control pot. This will depend on the gain of the input transistors and their mismatch. Often the offset will not be too bad. Less than 0.1 V is actually quite safe . Most guys would like to keep it under 20 mV .
A 22 K resistor will give an input impedance of 18.7 K ohms. A 47 K resistor will give an input impedance of 32.4 K ohms. The 100K resistor is to take the input end of the input capacitor to dc ground. You can raise it , which will increase the input impedance. I would think that you can use 220K or 470K also. ( with 220k giving Zin of 20.8 K and 39.4 K respectively ). Increasing the 100 K will result in greater dc drop across it due to the input capacitor leakage current. So one must make a compromise. Maybe 220K is OK.
BUT , IF you use no cap at the input , you need to be very careful. Any accidental connection to something with dc will fry your speakers without any speaker protection relay. The input could also be damaged if the dc voltage is high like a tube preamp without a coupling cap !
Might be a better idea to try out various caps at the input and pick what you think sounds best. That way you don't give the amp a chance to start 'smoking'. " Smoking kills" !
Note: the input impedance is a 100K parallel 11K. That works out to 9.91K ! The 11K is 1K in series and 10 K at the actual input of the circuit. You can raise the 10 K to 22k or 47K. This will increase the dc offset at the output of the amp for which there is no control pot. This will depend on the gain of the input transistors and their mismatch. Often the offset will not be too bad. Less than 0.1 V is actually quite safe . Most guys would like to keep it under 20 mV .
A 22 K resistor will give an input impedance of 18.7 K ohms. A 47 K resistor will give an input impedance of 32.4 K ohms. The 100K resistor is to take the input end of the input capacitor to dc ground. You can raise it , which will increase the input impedance. I would think that you can use 220K or 470K also. ( with 220k giving Zin of 20.8 K and 39.4 K respectively ). Increasing the 100 K will result in greater dc drop across it due to the input capacitor leakage current. So one must make a compromise. Maybe 220K is OK.
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You are right with the 10k input impedance calc. ashok, my bad as I read R18 value wrongly on the schematic.
I am concerned though, about an LDR volume controller that appears to be a bit too basic and perhaps does not have a buffered output. Daddy dj would be better served by a more flexible device that didn't require such high (100k) load impedance and hence higher amplifier noise level.
http://stores.ebay.com.au/stereocoffee?_trksid=p2047675.l2568
Personally, I would make best use of the existing low impedance impedance input for its low noise advantage. I fitted an (alleged) ALPS 10k pot to mine) and it is dead quiet with 89dB sensitivity speakers. 'Sounds superb too.
I am concerned though, about an LDR volume controller that appears to be a bit too basic and perhaps does not have a buffered output. Daddy dj would be better served by a more flexible device that didn't require such high (100k) load impedance and hence higher amplifier noise level.
http://stores.ebay.com.au/stereocoffee?_trksid=p2047675.l2568
Personally, I would make best use of the existing low impedance impedance input for its low noise advantage. I fitted an (alleged) ALPS 10k pot to mine) and it is dead quiet with 89dB sensitivity speakers. 'Sounds superb too.
A pre-amp or Buffer feeding a power amplifier needs a DC protection for the speaker.
That can be either a DC blocking capacitor, or a DC detection and isolation "system".
If one goes for the very simple DC blocking capacitor, then you only need the capacitor at the output of the Pre-amp/Buffer OR at the input of the power amplifier.
One does not need both ends of the interconnect cable to be DC blocked.
If both ends are DC blocked, then look inside and see which is the better cap with an appropriate frequency roll off.
Bypass the inferior DC blocker.
That can be either a DC blocking capacitor, or a DC detection and isolation "system".
If one goes for the very simple DC blocking capacitor, then you only need the capacitor at the output of the Pre-amp/Buffer OR at the input of the power amplifier.
One does not need both ends of the interconnect cable to be DC blocked.
If both ends are DC blocked, then look inside and see which is the better cap with an appropriate frequency roll off.
Bypass the inferior DC blocker.
Comments about DC Blocking duly noted, The TPA3116 has Epcos MKP X2 caps (cant see the value due to how it is mounted in the case)...does the L12-2 have no DC blocking caps on board?
The LDR I have seems to work pretty well with the TPA3116, the board I have has an input impedance of 30 kOhm
What would be recommended for DC blocking on the L12-2 to use with the LDR?
Thanks for the Input.
The LDR I have seems to work pretty well with the TPA3116, the board I have has an input impedance of 30 kOhm
What would be recommended for DC blocking on the L12-2 to use with the LDR?
Thanks for the Input.
If you could find a contemporary solid state amplifier with at least 50k input impedance, the cap could be as little as 1.0 uF. Lower impedance inputs require more capacitance for the same bandwidth and the L12 comes with C5, 10uF (see schematics posted at #6, #12)
If the LDR unit's seller recommended a minimum load of 50k though, it would be unwise to try and use it with a 10k impedance amplifier.
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Given the design details of the LDR unit, we may be able to suggest some less drastic changes than scrapping it, like including a buffer stage in it if necessary, since there ought to be one following the LDR unit anyway. However, as we are off the L12-2 topic with that, a new thread would be in order in the Analog Line Level forum.