That doesn't make sense. The pre needs to be on before the amp
Well, there is some reason the preamp waits to click in.Hi all,
I finished my GC. I attached some pictures of the first DIY GC. My bother helped me much in doing the case.
We also looked around for a pair of bookself speakers and finally decided to choose JBL2080 to start our hi-fi listening. Actually, there are some other brand name old pairs that the seller introduced: MS, B&W, Altec Lansing, Audit HRM-2, Phillips. All are old but in very good condition. Very like to listen to Audit but as budget reason and we both agreed that should begin with some "beginning level" first. C'est voila, JBL2080 was picked.
Together with GC, it immediately became our buddy everytime we are at home. Listen to music is naturally and totally relax. The bass of JBL2080 is very comfortable, we love it. And high is clear, crisp, And GC (thanks to premium kit from Peter) and JBL2080 is like a mom with two daughters wandering on the beach when the sun is going down. Beautiful sounding. My brother comments that listen to music is now not tired and we can do it hours and hours, days and days. No wonder someone out there pay much effort for better and better sound.
We are enjoying our music and time.
Thank you very much, Peter!
I finished my GC. I attached some pictures of the first DIY GC. My bother helped me much in doing the case.
We also looked around for a pair of bookself speakers and finally decided to choose JBL2080 to start our hi-fi listening. Actually, there are some other brand name old pairs that the seller introduced: MS, B&W, Altec Lansing, Audit HRM-2, Phillips. All are old but in very good condition. Very like to listen to Audit but as budget reason and we both agreed that should begin with some "beginning level" first. C'est voila, JBL2080 was picked.
Together with GC, it immediately became our buddy everytime we are at home. Listen to music is naturally and totally relax. The bass of JBL2080 is very comfortable, we love it. And high is clear, crisp, And GC (thanks to premium kit from Peter) and JBL2080 is like a mom with two daughters wandering on the beach when the sun is going down. Beautiful sounding. My brother comments that listen to music is now not tired and we can do it hours and hours, days and days. No wonder someone out there pay much effort for better and better sound.
We are enjoying our music and time.
Thank you very much, Peter!
Attachments
Nice build. I do agree with lohk. Pull them a few feet out from the wall. Even 4 ft might be good. Put yourself at the apex of triangle with all sides equal to 9ft. Some folks do 6ft. Depends on size of your room I guess. Turn the speakers inward so that the apex now crosses a few feet in front of you. Play with this apex distance from your face. This is a good place to start.
Uriah
Uriah
Oh and ohh... I didn't realize that it is the worst position. Thought the space is open in front and have enough distance (15cm) from the wall will make the listening well already.
I arranged this position because of the size of my room (2.8m x 3.0m) and hoped this was appropriate. You know that is a student's room and moving something big requires quite a messy arrangement.
I will try to bring them to the living room and persuade my friends to share the test. I know I must put them back here in my room then but I will do some research about best postion in small room first.
Thanks a lot, lohk and uriah.
I arranged this position because of the size of my room (2.8m x 3.0m) and hoped this was appropriate. You know that is a student's room and moving something big requires quite a messy arrangement.
I will try to bring them to the living room and persuade my friends to share the test. I know I must put them back here in my room then but I will do some research about best postion in small room first.
Thanks a lot, lohk and uriah.
Peter,
I wonder if I can power your GC with battery (car or motobike battery for example)? What should I do? Any performance affection?
As back to my country, the main power is not stable and sometime it is cut for even a whole day or more, I am considering the battery instead. Read about this in Mother-of-Tone with BYOB amp and DAC but still doubt it is applicable for GC LM3875.
Any suggestion?
Thanks,
HT
I wonder if I can power your GC with battery (car or motobike battery for example)? What should I do? Any performance affection?
As back to my country, the main power is not stable and sometime it is cut for even a whole day or more, I am considering the battery instead. Read about this in Mother-of-Tone with BYOB amp and DAC but still doubt it is applicable for GC LM3875.
Any suggestion?
Thanks,
HT
Thats an interesting thought!!
Building a GC for car !!.
Any plans somewhere for that kind of power supply?
Nick
I have poewered a gainclone with four 12V batteries (+/- 24V) with very good effect - I still believe it maybe sounded better than with mains power. But it was only temporary.
The SLA batteries were used ones from alarm lights and gave plenty of power. I think car batteries would also be sufficient.
Powering a gainclone with a LM3875 from a single 12V battery (like in a car) is IMO only possible with a voltage converter (like in most higher powered car amps), with a lot of effort and very unpredictable side effects to the amplifier's sound.
The SLA batteries were used ones from alarm lights and gave plenty of power. I think car batteries would also be sufficient.
Powering a gainclone with a LM3875 from a single 12V battery (like in a car) is IMO only possible with a voltage converter (like in most higher powered car amps), with a lot of effort and very unpredictable side effects to the amplifier's sound.
In the datasheet there is a diagram for single supply ie. +12V/0V. Its meant for cars. Its more complicated but should work fine and sound good.
For LM3886 datasheet is saying must have 20V or more but then the graphs are showing operating conditions with ~10V and up.
Will check LM3875..
Ah, okay looked at the graph again, its the one showing supply current vs supply voltage and even though it shows supply voltage as being at a min of ~10V that means +/- 10V so really you do need ~20V all together. I just wonder if that is necessary in the single supply configuration. Maybe there is more info in some app note. Will look around a bit.
Uriah
For LM3886 datasheet is saying must have 20V or more but then the graphs are showing operating conditions with ~10V and up.
Will check LM3875..
Ah, okay looked at the graph again, its the one showing supply current vs supply voltage and even though it shows supply voltage as being at a min of ~10V that means +/- 10V so really you do need ~20V all together. I just wonder if that is necessary in the single supply configuration. Maybe there is more info in some app note. Will look around a bit.
Uriah
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Thought for sure I would find an automotive app note for something in OVERTURE series that would talk about 12V operation. From not finding anything I am thinking you must use min 18-20V/0V for single supply. The two car batteries in +-+- configuration will give you what you need for dual supply and would be easier than the single supply circuit.
Uriah
Uriah
Well lets see if I can Get some help with this one.
I'm finally getting around to putting my amp in a nice case. I built up a separate psu with a new transformer from Antek and the extra power supply board. It's all neatly installed in a box along with a +/-15 supply for the phono pre [see attached pic]. I have a four conductor connector handling just the GC supply which is +/- 35vdc at the output of the psu. There is a 3 ft cord connected to the GC temporary enclosure. I also have +/- 35vdc at the connector coming in. So everything appears to be right on so far. Now when I hook up the amp boards I pop fuses. Out of the 100 times I've traced the wires from the connector to the board I've found nothing wrong or different than the way the last supply was hooked up.
If I detach the purple wires [see pic]that carry the PG- wires to the star ground I can hook up the +/- vcd without a problem.
If I have the PG- wires attached and try to touch either of the +/- vdc wires from the amp boards to the appropriate pin on the connector it will spark
Anybody got any suggestions?
I'm finally getting around to putting my amp in a nice case. I built up a separate psu with a new transformer from Antek and the extra power supply board. It's all neatly installed in a box along with a +/-15 supply for the phono pre [see attached pic]. I have a four conductor connector handling just the GC supply which is +/- 35vdc at the output of the psu. There is a 3 ft cord connected to the GC temporary enclosure. I also have +/- 35vdc at the connector coming in. So everything appears to be right on so far. Now when I hook up the amp boards I pop fuses. Out of the 100 times I've traced the wires from the connector to the board I've found nothing wrong or different than the way the last supply was hooked up.
If I detach the purple wires [see pic]that carry the PG- wires to the star ground I can hook up the +/- vcd without a problem.
If I have the PG- wires attached and try to touch either of the +/- vdc wires from the amp boards to the appropriate pin on the connector it will spark
Anybody got any suggestions?
Attachments
I am building a pair of gain clone mono's. and have a pair of 25v 25v 300va avel lundy transformers i'd like to use. Most of the gain clones are using 22v transformers. The original humpties use a 23.6 volt tranny don't they? Can i use these 25 volt ones? should i worry about the extra voltage? Can i make use of the xtra voltage to improve the performance? What values would you recommend for some induction post transformer to soothe the peaks a bit? I also have a pair of air gap 3 henry inductors, wouldn't these reduce the PS output voltage and smooth it?
anystereo,
I personally use 300, 25x2 and it's perfect for my GC. I got some level-0 questions here (http://www.diyaudio.com/forums/audi...it-building-instructions-138.html#post2468041 and http://www.diyaudio.com/forums/audi...it-building-instructions-139.html#post2476239) and they were all solved. I even remember Peter has suggested that with high power toroid (>300VA) the sound is stronger but no need for more than 400VA (http://www.diyaudio.com/forums/audi...kit-building-instructions-37.html#post1707916)
HT
I personally use 300, 25x2 and it's perfect for my GC. I got some level-0 questions here (http://www.diyaudio.com/forums/audi...it-building-instructions-138.html#post2468041 and http://www.diyaudio.com/forums/audi...it-building-instructions-139.html#post2476239) and they were all solved. I even remember Peter has suggested that with high power toroid (>300VA) the sound is stronger but no need for more than 400VA (http://www.diyaudio.com/forums/audi...kit-building-instructions-37.html#post1707916)
HT