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group buy for DX Blame MKIII Hx PCBs

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50 are being made. If we go over 50, send me an e-mail anyway. Some people may back out.

If you see an error on the list, send me a PM please.

Hi Byron,

Thanks for your hard work. It looks great (and large!) With its pedigree it should sound wonderful.

I just wanted to be sure that I have not perhaps missed the payment request, or is that still coming? Will you make the request here on the forum or send individual email or Paypal invoices?

Francois
 
Dear Evette... i have asked you to reduce your order

Please, dear Evette, confirm your quantity of order here...i do know you will keep order to Meanman group buy...i would like to know the quantity here...to confirm...you have asked 6....but maybe you will reduce.

Boys.... condensers you have in the power amplifier pcboard are auxiliary...they are there to fill the gaps...without them we had too much empty space there... board without anything on it.... free space...room to be filled with something.... then Alex decide to put condensers...and this was a very good decision.

Try to imagine this board without them, will be ugly .... so, they are there to add more capacitance..this way, your power supply will not need to have all capacitors there...you will have a smaller power supply..so..saving space into the power supply and using free space we had in the audio power amplifier pcboard.

Power specification charts (MKIII thread) show you the transformer power, also the needed current considering each particular situation ...say...8 ohms or 4 ohms or 2 ohms...also if you will use a single supply or if you will use two power supplies...there you can realize the fuses....but i will prepare (soon) a chart informing fuses to each particular situation.

Tekko.... go back some posts and you will see price.... also Byron will soon inform you.

regards,

Carlos
 

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Please, dear Evette, confirm your quantity of order here...i do know you will keep order to Meanman group buy...i would like to know the quantity here...to confirm...you have asked 6....but maybe you will reduce.

Boys.... condensers you have in the power amplifier pcboard are auxiliary...they are there to fill the gaps...without them we had too much empty space there... board without anything on it.... free space...room to be filled with something.... then Alex decide to put condensers...and this was a very good decision.

Try to imagine this board without them, will be ugly .... so, they are there to add more capacitance..this way, your power supply will not need to have all capacitors there...you will have a smaller power supply..so..saving space into the power supply and using free space we had in the audio power amplifier pcboard.

Power specification charts (MKIII thread) show you the transformer power, also the needed current considering each particular situation ...say...8 ohms or 4 ohms or 2 ohms...also if you will use a single supply or if you will use two power supplies...there you can realize the fuses....but i will prepare (soon) a chart informing fuses to each particular situation.

Tekko.... go back some posts and you will see price.... also Byron will soon inform you.

regards,

Carlos


condenser location is good Carlos , ( close to outputs ) and in this case can be second stage of Capacitor bank ...
 
Hi Byron,

Thanks for your hard work. It looks great (and large!) With its pedigree it should sound wonderful.

I just wanted to be sure that I have not perhaps missed the payment request, or is that still coming? Will you make the request here on the forum or send individual email or Paypal invoices?

Francois

Payment requests will go out individually via PM or e-mail when the boards arrive, and I've checked them. By "check" I just mean test for continuity or shorts and look for obvious mistakes. :xfingers: Different buyers will pay different shipping, depending on location.
 
About adjustments.... some details about

I am uploading video about...but here you have some images attached.

A new updated schematic is attached too, the 8K2 resistance was removed, as it was there to adjust off set only...in the reality it does not belongs to the schematic...some guys may use if needed, others will not.

When differential pair has matched transistors we do not have huge off set.... manufacturers accept off set up to 25 milivolts...and 300 milivolts of off set (huge one) represents only 11 miliwatts (0.011W) and this is nothing, or half of anything..will not move your speaker, will not harm your amplifier, will not produce sound when you power your amplifier on..so..do not worry.....BUT..if you want, you can fix and images shows how to do that.

You will see that Miller capacitor, the compensation one is 56 pf in the schematic....not correct, this is for future tuning and i will have to show you a safe way to do that without destroy your power output transistors...use 180pf as before.

Bias transistor can be anyone you find in your junk box...the plastic ones (material that has plasticity, not real plastic) are insulated and does not need washer, insulator and all that stuff is absent..not needed for them..so, it is more better..... transistor there will face (bias circuit) a few miliamperes and 2.2 volts..power there is very small..also voltage there is 2.2 volts as i said.... any transistor will fit...BUT.... each transistor has it's proper gain..so, the base to emitter resistance network should need adjustments in order to achieve the correct bias for this transistor that will supply 2.2 volts to bias the drivers and output trainees.

Bias point, or bias current, suggested, must be very low..in order to keep heatsinks cool while in stand by mode.... 1 milivolt measured as voltage drop across the power emitter resistances is all you need...of course you can change this in order to follow your ideas and beliefs....it is up to you..but you gonna be responsible for that..not uncle charlie.

The bias transistor is also a thermal compensating device...when heatsinks goes hot, then this transistor goes hot too..when it is hot its internal resistance drops down.... so, the previous 2.2 volts adjusted (from coletor to emitter) will be no more 2.2 volts..it will reduce...in the reality, when hot, your amplifier will show you much more current in stand by mode..and bias transistor will help to control that for you ..please, do not adjust your amplifier while hot..because when it return to a cool operation it will be underbiased or will have output transistors off, operating as class B, and this distorts low level signals.

I hope this helps.

regards,

Carlos
 

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More about adjustments.... the Dx Blame MKIII-Hx setup

You need huge..really huge heatsinks... this amplifier can reach one kilowatt (distorting as a crazy dog barking)..but it can go to that power during audio peaks and transients while using 2 ohms loads.... this will produce a lot of heat...if you do not have huge heatsinks the thermal compensation will not make miracles..will be unable to fix that wrong sittuation about heatsinks.... you will have thermal avalanche and your output transistor will be destroyed.

1000 watts in my mind represents a heatsink that is equivalent (area exposed to the air) to 100 (yes, a hundred) aluminium blades measuring 10 bv 10 centimeters.... this is for continuous power at 30 degrees celsius environment temperature..if heatsink is in the correct position and outside the enclosure (not obstructed)..this is for continuous.... to music (average) you can have a 2 kilowatt audio amplifier using this heatsink (100 blades one)

You have to produce your supply..use industrial heatsinks...the huge ones..for 30 amperes to each channel.... i have not suggested series coils..because will be hard to use them with the current we gonna drain...better not to use them..will be a hell on earth..they will overheat and will burn your board and will result in voltage drop there because resistance, even small, is something enougth to drop some volts because of huge current crossing it.

The video:

‪Adjustment to Dx Blame MKIII-Hx‬‏ - YouTube

More images attached,

New updated schematic attached.

regards,

Carlos
 

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down the home stretch!

Boards are scheduled to be shipped to me August 4, Thursday of next week. We currently have orders for 4 more boards than will be made. So two of you are in a "wait list".

I've been told it is common for some people to back out when it comes time to pay:mad:, which means those on the wait list (in red) will probably get your boards.

Also, Meanman is running a group buy for the same boards in Europe, on a different forum, and he may have extra boards.
 

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Mine lower power versions will have help, follow up, support and schematic published

when released in December,24th as Christmas gift to myself and to my friends from the Dx Corporation...i made that, the decision to publish latter, in order not to empty this group buy.

I will not stimulate, nor help, builders of my non published low power versions as they are in development..... i must test them and some modifications will be made in order to match (perfectly) the new supply voltage and output power.

I feel sorry as i have opened my damn big mouth and i have one already giving up to order boards...this worries me a lot...because Byron will have to eat non sold boards....but it is all right....he may give me a board if this happens..and this is interesting to me...hehehehehe.

In October i wil release another board, made by another man, a new layout, and this one will be for a little bit less power and gonna use 4 pairs n the output..... the Home Edition will be for 50/100W (December) and the Mini Edition will be for 20/40 Watts (aproximattely) and will be released in December too).

regards,

Carlos
 
Byron is producing part list...or Bill of Material (BOM)

But this is extremely rigid....a non flexible list that shows suppliers, part numbers, codes and you have to order exactly that ones without have the change to use parts you already have..from junk, saved or previously ordered parts.

I decide to answer a question Byron has made in video, to help all of you to take your own decisions about capacitors values.

Please, download at google transistors datasheet to know where is base, colector and emitter not to install them inverted by accident.... 2N5401 and 2N5551 are tricky as they do not use the same pin others transistors use..be carefull with these folks.

Sorry, audio is long...i use to talk too much..but i hope this may help, at least, one of you...this will make my effort valuable.

‪Audiophoolery about capacitors - part 1‬‏ - YouTube

‪Capacitor Audiophoolery - Part 2‬‏ - YouTube

regards,

Carlos
 
If Byron sells all the boards except for the two I asked for, I will happily buy the boards. I did not intend to leave him in a comprimisd position. I saw that others wanted the boards, so I offered. As I said, I will happily meet my commitment if it keeps him from eating any boards.
 
It seems to me, dear Buzz, that if you give up will not be a trouble to him

he is having more orders than he can provide..so...if you give up may be a help for him.

No problems..it is all right dear Buzz...i do understand your reasons..you are free to go ahead or give up.

Never mind...i was just having my concerns about.... my own regrets about my damn big mouth that makes me talk too much and play against my group of cooperative friends..they open group buys and sometimes i do my sabotage (without the intention to do that).... offering options that may produce people giving up.

Byron have asked me not to do that...but i failed about that...talking too much.

Not your fault Buzz...was mine fault...sometimes i am deeply stupid.:eek:

regards,

Carlos
 
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