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Old 3rd April 2012, 05:58 PM   #131
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I have made some changes to the original assembly guide, due to different reasons:

1-. Glued not only the big 220uF capacitor, but the smaller 100uF cap against the 0.22uF coupling capacitor too. It seemed to be the only piece "dancing" in the amplifier so, why not?

2-. Neither of the transformers nor the choke are grounded. They are even isolated from the chasis by means of plastic isolators. Is it not generally recommended to ground transformer's core to Protective Earth?
I have volmetered power trafo core and... it is at 39v above ground!! quite enough to shock a wet hand if touched! The other trafos have voltage on them but not as high.

3-. I added a second fuse to the input. IT IS A GREAT FAILURE NOT TO DO IT if you live in a country where you don't know on which pin LINE and NEUTRAL are, like most european countries. If I connect it to the wall, I may be fusing the line (I don't know unless measuring with a voltmeter). If I flip the mains plug 180, now I am fusing the neutral AND NOT the line. Which is like fusing anything.
If you live in a country where mains plugs on the wall have no polarity, it is a must to add a second fuse. Going further, it is illegal to not do it (fuse mains line). Going further, in case of failure you get a 50% chance of dying electrocuted.

4-. Another importans issue, specially when in the testing stage, is to add a permanent bleeder resistor to dicharge the capacitors. High ohmmic value enough to not suppose a considerable load to the PSU, but low ohmmic value enough to dicharge the capacitors fast enough. I can't remember the value I used, I think it forced around 1-2mA through the resistors, so make the maths assuming +400v. It takes the capacitors (with no tubes plugged) to 0v in around 30 seconds.

5-. No ON light indicator is issued with the kit, so I added a blue LED which serves two purposes:
-Giving an indicator that power is ON and the amplifier is plugged to the wall.
-Because the LED has a voltage drop of 2v, it will shut off as soon as PSU voltage goes lower than 2v (more or less). That helps to show that HV capacitors have no voltage across them.
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Last edited by regiregi22; 3rd April 2012 at 06:03 PM.
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Old 5th April 2012, 07:16 PM   #132
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Hi Regi,

The amp looks great. Good job. Glad you like the sound.

In reference to post #121 above, and the transformer core grounding.

Although I have been assured by the manufacturer that the transformer windings are extremely well isolated from the core, I am going to suggest the following additional safety method of mounting the output, & power transformers, and the choke to the chassis:

1. Use the plastic bushings only for the top of all transformers and choke outside the covers, as indicated in the manual. Do not use the plastic bushings between the transformers and choke, and the chassis.
2. Scrape away the varnish from around at least two of mounting holes for the transformers and choke where they come in contact with the chassis.
3. Use a star washer between the two points described above in #2, and the chassis.

I will be notifying all purchasers of the master kit with laydown-style transformers of this additional safety procedure.

With reference to mention of a second fuse: The amp is supplied with an IEC grounded receptacle for connection of AC power. I am guessing your receptacles are the grounded Schuko type? Thanks for bringing this to my attention. I will make an addendum to the manual suggesting the additional fuse for users of this amplifier with European style power receptacles.



Thanks,

Scott

Last edited by scott17; 5th April 2012 at 07:25 PM.
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Old 22nd April 2012, 04:25 AM   #133
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The Master Kit and fully assembled amp are still available.

Demo available on Saturday/Sunday near JFK airport.

Send a PM if interested.
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Old 22nd April 2012, 05:28 AM   #134
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The demo will be conducted using the 2-way horn-loaded loudspeaker system that I have designed specifically for this outstanding amplifier.

Be prepared to personally witness a new benchmark in music reproduction.

Scott
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Old 22nd April 2012, 06:16 AM   #135
TerryO is offline TerryO  United States
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Quote:
Originally Posted by scitizen17 View Post
The demo will be conducted using the 2-way horn-loaded loudspeaker system that I have designed specifically for this outstanding amplifier.

Be prepared to personally witness a new benchmark in music reproduction.

Scott
Scott,
Would details of that "2-way horn-loaded loudspeaker" design be available to those that are geographically challenged and cannot attend, but never-the-less "need" a Hi-Efficiency speaker to go with their amp (like DaveR!!!!).


Best Regards,
TerryO
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Old 22nd April 2012, 05:15 PM   #136
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Yes, details available. Here you go. The speakers are Deltalite II 2510 & Ciare 1.38TW.

I should have said that the amp is available for demo on any Saturday or Sunday as long as I am in town.

Scott
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Old 23rd April 2012, 10:53 AM   #137
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Quote:
Originally Posted by scitizen17 View Post
The demo will be conducted using the 2-way horn-loaded loudspeaker system that I have designed specifically for this outstanding amplifier.

Be prepared to personally witness a new benchmark in music reproduction.

Scott
I may agree, this is quite tru regarding amplifier's quality.

I have made more tests on in and I have to add that the problem related to lacking bass was due to my speakers. They are small ones and with low sensivity, around 88db/W.
I tested the amplifier on a pair of 91db/W tower speakers and it sounded VERY GOOD! Bass was there again, even it was more present in the room compared to my 300watts amplifier BPA-300. Very creamy and natural sound, I just love it
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Old 24th April 2012, 04:19 AM   #138
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Happy Birthday Regi!

Quote:
Originally Posted by regiregi22 View Post
I may agree, this is quite tru regarding amplifier's quality.

I have made more tests on in and I have to add that the problem related to lacking bass was due to my speakers. They are small ones and with low sensivity, around 88db/W.
I tested the amplifier on a pair of 91db/W tower speakers and it sounded VERY GOOD! Bass was there again, even it was more present in the room compared to my 300watts amplifier BPA-300. Very creamy and natural sound, I just love it
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Old 24th April 2012, 04:44 AM   #139
Dave R is offline Dave R  United States
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Quote:
Originally Posted by TerryO View Post
Scott,
Would details of that "2-way horn-loaded loudspeaker" design be available to those that are geographically challenged and cannot attend, but never-the-less "need" a Hi-Efficiency speaker to go with their amp (like DaveR!!!!).


Best Regards,
TerryO
Thanks Terry, but first, I just need to finish the last project that you encouraged me to work on!
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Old 24th April 2012, 05:15 AM   #140
TerryO is offline TerryO  United States
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Originally Posted by Dave R View Post
Thanks Terry, but first, I just need to finish the last project that you encouraged me to work on!
Dave,

I have so many ideas and you have so few hours!
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