Dx Blame ES .... based into the Blameless, i am trying a new amplifier

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taj

diyAudio Member
Joined 2005
I see a minor mistake on the layout. The 220R resistor was changed to 100R in the schematic, but not on the layout. I'll fix that in the update.

..Todd
 

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Yes, of course will be better, but board was tested.

Amplifier was tested 4 times... aproved!, ready to go.

We are in a time of parties, Christmas and New Year, so, everybody is a little bit busy having fun.

My fun is amplifiers, so, i am a non stop builder.

Happy new year.

I understand you want to do fast, i really think you should have done it yesterday , or the day before, because the sound is so good you will be mad because have never tried before.

I will enter portuguese words about at the google translator, to describe the wonderfull thing.

Doctor Douglas Self, the man!.... me, a very lucky guy, hard worker, that made the correct choice.

You gonna dance and cry because emotion, strong emotion are coming to your life...prepare yourself to see the Paradise on earth.... the land of music, pure and cristal clear music.

Treble, the amplifier has a lot, the bass is shy.

regards,

Carlos
 
Month of march i will release the Dx Blame ES II

I am observing the amplifier.... it does not like to operate with weak power supplies.

When the voltage drops, as a consequence of high power bursts beeing sucked from the supply, them the CCS supply voltage goes down too, this is no good because the long tail current will variate too.

In the future, the amplifier will have rail voltage regulators the same way the HRII has.

So, if we go using huge supplies, no problems, but if our supply is no good, we gonna have disturbs in sonics.

the link is youtube small video, showing the Dx Blame ES square wave frequency sweep, the heterodyne style beatings of sonics are because the digital camera recording, transforming a very high frequency into a lower frequency tone:

http://www.youtube.com/watch?v=hTJHUOqmHrg

Carlos
 

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First board made, taj board, the guy said

"since the first second you power the unit on, you feel it is in another level of quality, really have beated all other Dx amplifiers, you should assemble to feel what i am feeling"

Sorry, he used Cell phone camera, but the image is will belong to the Corporation history.

I will repeat... this is the best, i have never listened so detailed reproduction, beated others by great advantage, Dx amplifier is 75, this one goes 96!

Sorry competition, i guarantee to you a second place..do not even dream to beat this one...just impossible!

regards,

Carlos
 

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Happy New Year to the DX corporation members!

I noticed when you tried to tweak th DX Blame ES stability, I see in every schematic the feedback capacitor 18 pF is almost never touched, I wonder if you would have increased it, instead of dumping the VAS output signal, could also have bettered the amplifier stability?
The dumping of VAS output could also instead be used for increased local feedback by larger "Miller" capacitor, and at the same time increase the feedback capacitor equally as much, these are the 2 capacitors one would perhaps look at first before anything else, any thoughts here?
One could think like this, if there's "too much" gain which could cause instability one could instead use local degeneration which both linearise and lower the gain, the VAS dumping cap is doing nothing in comparison.
Anyway, congratulations, you made it before the turn of the year and made many happy!

Cheers Michael
 
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Happy new year to you too dear Ultima.

I have tried today, i have removed, also increased, and the unstability was fixed using the 100 pf from base to colector in the CCS transistor and the 470 pf in the VAS BD139, from colector to emitter.

I was supposing something bad could result,but i could not see problems in the waveform, yeah, the slew rate changed, the square wave rise time was increased, you see in the picture posted we do not have vertical, we have angle.

I tried the simulator, to see the distortion and i resulted increase from 0.00095% to 0.001%.... i tried the 100 Khz sinus to see if changed to a triangle and i found good.

Listening, i have not perceived losses...well Ultima, i think maybe some degrées of unobtanium and inexistiun distortions was increased, but i could not perceive.

A warm hug for you dear Ultima..do not forget, we have a beer around the swiming pool to have together.

regards,

Carlos
 
Interesting the zobel was fixing the stuff Ultima..when removed the amplifier

became more stable or less unstable, before i have made the other modifications... the amplifier could not even sniff capacitances kilometers away that started to oscilate.

Now i can install 2.2uf, of course the square wave shows some damping...but.... i hope no one will install 2.2uf in the output.

Works very cold, all transistors cold, i can feel something in the second VAS, maybe 7 degrees above my environment temperature, here i am having 30 degrées célsius, and the transistor case seems 37 or 38 degrees.... light human fever temperature.

Well, oscilations are now past.

Carlos
 
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Thanks Carlos I was little curious so no problem, I trust the Brazilian engineering, you have put a lot of energy into it in the past days and weeks and find a good compromise that please both the ears as well as make it "sniffing on capacitor" little bit closer without becoming upset, well done!

And thank you for your new years wishes too, very kind and I have not forgotten the meeting around swimming pool, you know if I come to Brazil at least 2016 I will make sure come by you too.

30 degrees, oh you have really comfortable weather, we have maybe -15 and it has been snowing for 2 weeks almost constantly, absolutely amazing and the landscape is like a white fluffy dreamscape, very quiet as the snow dampens a lot the background noise in the city. Talking about temperature, in my past profession in a design a power mosfet working with almost 900 Volts peak amplitude it had to work in a heat chamber test and were tested for 60 degrees environmental temperature, the body temperature of the TO-247 package was 115 degrees, that is very hot.

I think it's less than a half hour for Brazil to start celebrate the new year, hope you have a great evening!

Cheers Michael
 
Thank you Ultima.... Brazil Northeast does not follow the

National time, we have the Brazilian Brasilia time, because Brasilia is the country Capital and it is in the Geographic center.... our width would result in 5 hours difference i think, from East to West....but we have the Brasilia time to all country..... in special, the Northeast does not enter the summer time...so, we are one hour delayed related others.... the rest of the country will celebrate in 6 minutes...but i will celebrate 1 hour and 6 minutes in the future.

regards,

Carlos
 

taj

diyAudio Member
Joined 2005
Updated PCB, Schematic, BoM v1.2

Updated PCB, Schematic and BoM v1.2 attached.

I hope this solves everything. Peace on earth should be do-able, not sure about socially-functional electrical engineers.


..Todd (by the way, happy new year)
 

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Bom

DX Blame ES parts list (for one channel)
Rev. 1.2 © 2009/2010 Carlos Mergulhão

Transistors:
Device # Value Notes
Q1,Q2,Q3 BC556 Pinout=cbe
Q4,Q5,Q6 BC546 Pinout=cbe
Q7,Q8,Q9 BD139
Q10 BD140
Q11 2SC5200 or FJL4315, or 2SC2922
Q12 2SA1943 or FJL4215, or 2SA1216

Capacitors:
Device # Value Lead Spc Type Notes
C1 10uF/16v 2mm ea. Electrolytic use 2 back-to-back or use film
C2,C4,C5,C6,C9 100nF 5 or 10mm film aka: 0.1uF polyprop. or polyester
C3 220pF 5mm mica, polystyrene or polyprop. or NP0 or C0G ceramic
C7 220uF/16v 3.5,2.5mm Electrolytic
C8 47uF/25v 2,2.5,3.5mm Electrolytic
C10 47uF/100v 5mm Electrolytic
C11 18pF 5mm mica, polystyrene or polyprop. or NP0 or C0G ceramic
C12 100F/16v 3.5,2.5mm Electrolytic
C13 82pF 5mm mica, polystyrene or polyprop. or NP0 or C0G ceramic
C14,C16,C20,C22 470uF/50v 5mm Electrolytic
C15,C17,C19,C21,C23 47nF 5mm film aka: .047uF, polyprop. or polyester
C18 220nF 5 or 10mm film aka: 0.22uF, polyprop. or polyester
C24 100pF 5mm mica, polystyrene or polyprop. or NP0 or C0G ceramic
C25 470pF 5mm mica, polystyrene or polyprop. or NP0 or C0G ceramic

Resistors: (all are .25W metal film, except where noted)
Device # Value Power Notes
R1,R16,R17 220R
R2 10K
R3 10R 0.5W
R4,R22 150R
R5,R6 100R
R7 470R
R8,R9 68R
R10 3K
R11,R12 8K2
R13 12K
R14 3K3
R15 2K7
R18,R21 33R
R19 2K
R20 470R
R23,R25 2R2
R26,R27 0R22 5W Mills non-inductive. Digi-Key: MRA05-.22-ND (4x14 mm approx.)

R28 15R 5W (no Mills avail.) Huntington ALSR. Digi-Key: ALSR5F-15-ND (4x14 mm)
R29 10R 5W Mills non-inductive. Digi-Key: MRA05-10-ND (4x14 mm approx.)

R30,31 2x 100R 1W Optional. Mount on underside of board. Used for adjustm., not for audio.

Miscellaneous:
Device # Value Notes
D1,D2 1n4148
D3,D4,D5 1n4001
Bias Trimmer 500R Bourns 3362P single turn or eqv. Digi-Key: 3362P-501LF-ND

Power, output, ground connectors 4x Faston .25" male. Digi-Key: A29938CT-ND

Fuse holders (5x20 mm fuses) 4x Digi-Key: F063-ND or eqv., need 2 per fuse
Heatsinks for drivers 2x Like Digi-Key: HS106-ND but not sure if these fit. Should do.
 
How to adjust the amplifier

I am waiting more guys to build (Brazilians, there are more three building) to receive from them some feedback about bias potentiometer start up preset resistance, this is variable, we cannot give you a magic number.... only a start number to try.

1) Remove the rail fuses
2) Install DC voltimeter in the fuse socket
3) switch on the amplifier power supply
4) adjust bias trimpot to read from 3.3 to 6 volts
5) Check both rails
6) Move DC voltimeter to the output line
7) Off set reading should be from 3 to 25 milivolts, usually it is 12mV
8) Reduce it if you want, place 820, 1K, 1K2 or 1K5 resistance in parallel with
R8
9) Switch your multimeter selector to ready AC volts and read the output line,
no AC voltage should be there.
0) Check once again your stand by current, if fine, them install fuses and
enjoy your amplifier.

If you experience overflow, or variations in the offset readings, them short the input to ground, after that, do not forget to remove the short you have made.

My home amplifiers, the prototypes, one used 1K resistance to reduce off set to 500 microvolts, the other has used 1K2, so, as you see, this is variable, depends on the differential transistor matching and some amplifier components.

The stand by bias trimpot is also something that changes depending the circuit, a good starting adjustment is 250 ohms, as one of my amplifiers asked for 160 ohms and the other was 330 ohms.

Adjusting your bias at 38 miliamperes, your output transistor will be draining 27 mA each one of them, the negative rail current will be 42 mA, the 100 ohms protective resistance reading will be 3.8V up rail and 4.2V the lower rail,

The amplifier itself, has very low power consumption, the output is adjusted to dissipate, during stand by. 1 watt to each power transistor.

Driver transistors needs heatsinks, and it is a very good idea to install as small piece of aluminium, squared, 2 centimeters side, at the second voltage amplifier,the BD139.

regards,

Carlos
 
Basic specifications

1 Volt peak sensitivity at the input to produce full power output, around 20 volts RMS, or 50 watts at 8 ohms and 90 to 100 watts at 4 ohms (depending how strong is your supply)

Input impedance is around 10K

Distortion is bellow 0.0015% THD

Power supply needs: 25 to 27 volts AC output transformer, with center tap, able to feed 2.5 amperes each rail.

Amplifier efficiency is around 60 percent, so, to produce 100 watts of audio, each channel will be draining 160 watts from the supply.

The amplifier is flat, from 1 cicle to 100 thousand cicles.

Square wave having 10 kiloherz entering is fine, but 20 Kilohertz square wave shows the rise time slower.

The amplifier is flat, but the high frequencies appear (audible) as dominating, the bass is controled and precise, also present and nice, but seems shy compared to the treble that is magnificent.

regards,

Carlos
 
Yes, there's a short there

Also a brazilian friend told me i forgot the bypass capacitor in parallel with C7, a 47n or 100n.... this i do not know if there's room in the pcboard to include.

The amplifier can work without this bypass capacitor, but having it will be even better.

regards,

Carlos
 

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