Group order of non-inverted LM3875 pc boards? Anyone interested? - Page 29 - diyAudio
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Old 14th March 2004, 06:44 PM   #421
BrianGT is offline BrianGT  United States
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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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Old 14th March 2004, 07:04 PM   #422
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by KT
Hi Brian,

Missed out on the group buy (unexpected expenses came up), but look forward to purchasing a few kits in the next month or so. Please keep us posted....really looking forward to it!

Best,
KT
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.p...Order+Phase+II

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Brian
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Old 15th March 2004, 12:54 AM   #423
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Default Victoria Magnetics

Brian,

Does John at Victoria have the specs for your recommended transformer?

Congrats on the upcoming nuptials!

David
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Old 15th March 2004, 02:40 AM   #424
BrianGT is offline BrianGT  United States
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Default Re: Victoria Magnetics

Quote:
Originally posted by net-david
Brian,

Does John at Victoria have the specs for your recommended transformer?

Congrats on the upcoming nuptials!

David
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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Old 15th March 2004, 10:39 AM   #425
roibm is offline roibm  Romania
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Default Re: Re: Victoria Magnetics

Hi Brian

Quote:
Originally posted by BrianGT
I told John that it should be 320va 2x24vac.
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?
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Old 15th March 2004, 10:54 AM   #426
BrianGT is offline BrianGT  United States
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Default Re: Re: Re: Victoria Magnetics

Quote:
Originally posted by roibm
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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Old 15th March 2004, 03:43 PM   #427
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What is the model attenuator in your demonstration GC? Would you be so kind as to suggest a suitable pot for the budget minded?

Lastly, I would suggest that anyone who can solder (or roof, or hammer, or mow, or SAIL) is a very suitable marriage partner. Congratulations!
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Old 15th March 2004, 04:07 PM   #428
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by chipco3434
What is the model attenuator in your demonstration GC? Would you be so kind as to suggest a suitable pot for the budget minded?

Lastly, I would suggest that anyone who can solder (or roof, or hammer, or mow, or SAIL) is a very suitable marriage partner. Congratulations!
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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Old 15th March 2004, 04:30 PM   #429
mls is offline mls  United States
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Default CD Pro2 kit

Quote:
Originally posted by BrianGT



Anyone interested in board (or kit) for the cdpro2? I know that Nico currently offers one, but my kit would be easier for those living in the US. I am also considering open-sourcing this project, so that people can modify the firmware anyway that they want. It is written in C, and has a serial bootloader. (free one month trial is available for the c compiler from the company that makes it)

I have gotten a few more requests for kits, and I will try to start taking orders again soon, as soon as I get a substantial number of the existing orders shipped out.

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Brian
Yes! Count me in, Brian. I sent you an email a couple of days ago as well. I'd at least be interested in pcbs, if not a kit.

Mike
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Old 15th March 2004, 04:45 PM   #430
widman is offline widman  United States
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Quote:
I bought some Alps 50k Black Beauty potentiometers for my next amplifier.
I've been looking at potentiometers to use with my pcb-kit and wondered if the following would be an acceptable option:

50k Alps

Thanks,
widman
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Old 15th March 2004, 06:43 PM   #431
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by widman


I've been looking at potentiometers to use with my pcb-kit and wondered if the following would be an acceptable option:

50k Alps

Thanks,
widman
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:
Alps pot on ebay

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Brian
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Old 15th March 2004, 06:44 PM   #432
BrianGT is offline BrianGT  United States
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Default Re: CD Pro2 kit

Quote:
Originally posted by mls


Yes! Count me in, Brian. I sent you an email a couple of days ago as well. I'd at least be interested in pcbs, if not a kit.

Mike
I got your e-mail. It will be at least a month before anything else happens with my cdpro2 project.

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Brian
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Old 15th March 2004, 08:18 PM   #433
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Default 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.
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Old 15th March 2004, 09:09 PM   #434
BrianGT is offline BrianGT  United States
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Default Re: 6 channel amp questions

Quote:
Originally posted by jlh28
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.
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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Old 15th March 2004, 10:12 PM   #435
BrianGT is offline BrianGT  United States
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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
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