Thanks for the congratulations on the wedding, as it is 2 weekends from now 
Here is another picture of the amplifier pcb during the assembly process. I am finishing up the users guide now. I will also place higher resolution versions of the pictures on my website.
The negative feedback resistor, the 22.1k resistor seen attached to the LM3875 package, can also be soldered to the bottom the pcb, directly to the device pins, if you are to put it as it is shown. This resistor is the most important component in the amplifier and the shortest possible signal path for this component will result in the best possible performance of the amplifier.
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Brian
Here is another picture of the amplifier pcb during the assembly process. I am finishing up the users guide now. I will also place higher resolution versions of the pictures on my website.
The negative feedback resistor, the 22.1k resistor seen attached to the LM3875 package, can also be soldered to the bottom the pcb, directly to the device pins, if you are to put it as it is shown. This resistor is the most important component in the amplifier and the shortest possible signal path for this component will result in the best possible performance of the amplifier.
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Brian
Attachments
KT said:
KT,
I will be doing another group order in a month. I have created a Wiki for seeing how much interest there is for one:
http://www.diyaudio.com/wiki/index.php?page=NI+GC+PCB+Group+Order+Phase+II
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Brian
Re: Victoria Magnetics
I told John that it should be 320va 2x24vac. If you are ordering one, mention that you know me, and want to order this. Since you are located in GA, you can probably get a better deal if you go there and pick it up, as a portion of his cost is the packaging of the transformers. This seems to be a hassle, to pack the transformer without having it come out of the side of the box during shipping.
Thanks for the congrats getting closer.
To others, status update:
I am still putting kits together. Tonight, I spent at least 4 hours cutting apart the tubes that the LM3875 came in, and packaging them in packs of 2. This was quite a hassle, but I got it done for all the kits. I should be able to ship out a bunch of kits soon. My goal is to get most of them shipped out by the end of the week. Meredith has about 1/3 of the packages addressed, and I have put together a portion of the kits.
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Brian
net-david said:
I told John that it should be 320va 2x24vac. If you are ordering one, mention that you know me, and want to order this. Since you are located in GA, you can probably get a better deal if you go there and pick it up, as a portion of his cost is the packaging of the transformers. This seems to be a hassle, to pack the transformer without having it come out of the side of the box during shipping.
Thanks for the congrats
getting closer.To others, status update:
I am still putting kits together. Tonight, I spent at least 4 hours cutting apart the tubes that the LM3875 came in, and packaging them in packs of 2. This was quite a hassle, but I got it done for all the kits. I should be able to ship out a bunch of kits soon. My goal is to get most of them shipped out by the end of the week. Meredith has about 1/3 of the packages addressed, and I have put together a portion of the kits.
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Brian
Re: Re: Re: Victoria Magnetics
It depends on your speakers. I am running 4 ohm speakers with the 2x24vac transformer just fine, but if the impedence of your speakers is 4 ohms, and tends to drop quite low, I would go with the lower voltage transformer. If you are using 8 ohm speakers, it shouldn't matter.
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Brian
roibm said:Hi Brian
Do you(Peter? or anyone else) think it would be better if I would get a 340VA with 2x25V over the 250VA which has 2x22V?
It depends on your speakers. I am running 4 ohm speakers with the 2x24vac transformer just fine, but if the impedence of your speakers is 4 ohms, and tends to drop quite low, I would go with the lower voltage transformer. If you are using 8 ohm speakers, it shouldn't matter.
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Brian
chipco3434 said:
The one in the demonstration GC is the the asian stepped attenuator, which jrsun is selling. I would not recommend using this, as it makes popping noises as you change the volume steps. This is quite irritating, though it works well, once the volume is set. When changing volumes, it makes a sound similar to machine gun fire.
I bought some Alps 50k Black Beauty potentiometers for my next amplifier. I will be using Peter Daniel's chassis kit for my next gainclone:
http://www.specializedkits.com/integrated-amp.html
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Brian
widman said:
This pot is not a real alps, but a fake. It is ok for the money, but doesn't have the reliability of the real Alps pots. View this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=28792
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Brian
6 channel amp questions
I have 3 kits soon to be on the way, and I want to use them to power my HT setup for now. I just want to verify that a 960va 6x24vac transformer would do the job. Is that correct? I have already received a quote from Victoria Magnetics for the transformer, and I just want to be absolutely sure that it is what I need.
Now after I receive the transformer and begin the build, I should have no problem wiring it up because with the exception of the one transformer, it will be basically the same? Will someone let me know if anything needs to be done differently regarding the volume control or other components? I plan to use either an 25K noble or 50k alps Black beauty.
Thanks
from the banker who wants to be an electronics guy. I try to explain to people my hobbies, and it is if I am speaking an alien language.
I have 3 kits soon to be on the way, and I want to use them to power my HT setup for now. I just want to verify that a 960va 6x24vac transformer would do the job. Is that correct? I have already received a quote from Victoria Magnetics for the transformer, and I just want to be absolutely sure that it is what I need.
Now after I receive the transformer and begin the build, I should have no problem wiring it up because with the exception of the one transformer, it will be basically the same? Will someone let me know if anything needs to be done differently regarding the volume control or other components? I plan to use either an 25K noble or 50k alps Black beauty.
Thanks
from the banker who wants to be an electronics guy. I try to explain to people my hobbies, and it is if I am speaking an alien language.
Re: 6 channel amp questions
Jeff,
I just called up John at VM and verified what you stated: ~1kva, 6x24vac secondaries. I also mentioned that you should get a shield around the outside of it, as I have with mine. I attached a picture of the two transformers that I got from him a while back for my Aleph amplifiers.
(mine only have 4 pairs of secondaries, not 6)
They are 1kVA.
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Brian
jlh28 said:
Jeff,
I just called up John at VM and verified what you stated: ~1kva, 6x24vac secondaries. I also mentioned that you should get a shield around the outside of it, as I have with mine. I attached a picture of the two transformers that I got from him a while back for my Aleph amplifiers.
(mine only have 4 pairs of secondaries, not 6)
They are 1kVA.
--
Brian
Attachments
For those wanting to upgrade their order to use the BlackGate 4.7uF 50v N capacitors in the power supply, I will be receiving another batch of them from Michael Percy in a couple of days. Here is the payment page if you wish to upgrade your kit:
http://brian.darg.net/order/bg-upgrade.html
The price is the same, $5 for a pair of caps to go with your kit, replacing the 4.7uF Panasonic FC caps.
Drop me an e-mail if you have any questions.
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Brian
http://brian.darg.net/order/bg-upgrade.html
The price is the same, $5 for a pair of caps to go with your kit, replacing the 4.7uF Panasonic FC caps.
Drop me an e-mail if you have any questions.
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Brian
Brian, I was just thinking that since there seems to have been great interest in BlackGate caps for the bypass service and they were snapped up, you may want to consider offering the 1000 uF filter caps for the "premium" kit in your Phase II order. I'm guessing that they would be snapped up as well.
leadbelly said:
The problem is that the BlackGate 1000uF STD caps cost almost $15 each, meaning an extra $60 for 2 channels. This is quite expensive, and it has been said by some that the combination of the Panasonic FC capacitors with the BG 4.7uF N capacitor in the power supply is a great combination. I myself, will be content for now with the Panasonic FC 1500uF caps and the 4.7uF BG N combination.
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Brian
Yet another Transformer question
OK, If I run 2 channels using a single transformer of about 150 VA, that is woefully inadequite, everyone agrees on that I believe.
1. What will happen if I listen at reasonable levels- basically only somewhat more than background level.
2. What if I exceed it's capacity by turning it up too much?
Transformer gets hot?
Loss of dynamics?
Clipping?
Is there a built-in clippping limiter that makes a wierd sound?
Chip releases magic smoke?
Thank you,
MArk
OK, If I run 2 channels using a single transformer of about 150 VA, that is woefully inadequite, everyone agrees on that I believe.
1. What will happen if I listen at reasonable levels- basically only somewhat more than background level.
2. What if I exceed it's capacity by turning it up too much?
Transformer gets hot?
Loss of dynamics?
Clipping?
Is there a built-in clippping limiter that makes a wierd sound?
Chip releases magic smoke?
Thank you,
MArk
Re: Yet another Transformer question
I would expect it to be fine at low volumes, based on the current draw from a bench supply. If you crank it up, I would expect the voltate to drop on your transformer, and it would possibly get hot. As for clipping, this wouldn't happen, unless the voltage drops to a point greater than the gain.
The amplifier clips normally, and you should be to clearly hear it.
It looks like the big bass notes draw the most current, from watching the bench scope bounce around, so if you crank it high enough, you might lose some bass.
I don't expect the chip to release magic smoke. I would just monitor your power supply voltages, and the temperature of your transformer.
From watching the bench supply, I am amazed how little current the amplifier uses when it is running at low volumes, probably less than 100W (VA) for moderate listening levels.
Good luck. The best practice would be to try it out and post your results, as I am sure others are thinking the same thing.
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Brian
Variac said:
I would expect it to be fine at low volumes, based on the current draw from a bench supply. If you crank it up, I would expect the voltate to drop on your transformer, and it would possibly get hot. As for clipping, this wouldn't happen, unless the voltage drops to a point greater than the gain.
The amplifier clips normally, and you should be to clearly hear it.
It looks like the big bass notes draw the most current, from watching the bench scope bounce around, so if you crank it high enough, you might lose some bass.
I don't expect the chip to release magic smoke. I would just monitor your power supply voltages, and the temperature of your transformer.
From watching the bench supply, I am amazed how little current the amplifier uses when it is running at low volumes, probably less than 100W (VA) for moderate listening levels.
Good luck. The best practice would be to try it out and post your results, as I am sure others are thinking the same thing.
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Brian
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