Trust, the most delicious Dx Amplifier

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Condensers i will use connected in the Trust Amplifier output

They are output coupling condensers..there are several in parallel.

Attached,

regards,

Carlos
 

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To play with amplifiers, an old style amplifier, output is coupled using condenser

low power and delicious sonics..the most delicious sonics (coloured) i have made..distorts a lot while clipping..but sounds great when not playing too much loud.

Something to recall old style amplifiers, made using a little bit more modern parts.

Good for a weekend project, to use your time doing things that will be usefull and will bring you pleasant moments.

regards,

Carlos
 
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This is an interesting little amp. DX. Some people are always talking about old style single rail and caps in the output, EF input etc. etc.
All interesting but you built it for a reason, an idea, inspiration. Now when you think back to this time, how do you think about the sound? Maybe you can say a comment about what made you build it. I would appreciate this, thank you.
 
Coloured, filled with harmonic distortion, having some small loss in high end

reproducing a lovely warm deep bass...good precision....we can say high fidelity.

Well...match my taste....i think it is the most delicious..a very pleasant sonics.

But it is not the best, it is the most delicious one!

I have tried options...to offer several options.... i love people building my stuff..so..offering more options results more chances.

Power is small...almost underpowered to my taste..but sonics are nice...very nice.

regards,

Carlos
 
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Joined 2010
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Thanks. If you still have a board, maybe you could try it on 50-60 volts with a couple of cap changes. Probably not eh, you don't have the board anymore, I guess.

Anyway, I saw in your videos you have some nice little KEF IQ(x) speakers. Still have them? They are very sharp clear imaging IMO. Probably making an interesting complement with the old type amp design. Just a thought, my friend - no bother, please - you have probably tried all this before.
 
You can listen this amplifier...nice warm sonics..old style

Sound was equalized and sent to The Trust ..... output was captured using Panasonic electret condenser microphone...one meter distant and inside a housing (chamber) made uaing 4 matresses and the bottom was cement and brick wall.

YouTube - The Trust, old style amplifier

This amplifier does not measure fine as the more modern ones...but the sound is the most delicious..power is small too

regards,

Carlos
 
i'm a starter(a builder !), and wanted to try dx trust ^^ hoping for that delicious sound, but i can't find 8600uF for my application (well.... i wanted for 4 ohm speakers)

and i wanted to ask if i could make it flexible and work with either 4/6/8 ohm speaker ?
and about the heatsink, where should i install ? (can't found it anywhere)

additional question : I saw added a c5a parallel to c5, without much explanation, is it really needed there ?
 
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this kind of amp does sound good and a good amp to build - you don't need the exact same output capacitor, just that you use something with the same or higher voltage rating as per DX recommendation and if you have only smaller valued capacitors just parallel up enough capacitors to achieve something of roughly the same total value as DX used. For capacitors in parallel you just add up the capacitances of the separate capacitors to find their equivalent value instead of a single large one. For the best possible sonics, I believe using a larger number of capacitors of smaller value with voltage rating of 63V is better than one large capacitor.

this kind of amplifier should work fine with 4, 6 and 8ohm. Maximum power and distortion performance of the amp will vary between them but they should all work.

heatsink - well I'm not sure I understand the question, the output power transistors must be properly mounted to a sufficiently large heatsink to handle the power you want to use. I know that's a bit vague but it depends on the details of what you want to build. You want to ensure that Q3 is also mounted on the heatsink so that it can follow the temperature of the output devices, or mount Q3 with some silicone glue directly onto one of the power devices - it's used to control the current through the output to ensure it doesn't go uncontrollably hot and damage itself.

C5a is a small capacitor designed to go in parallel with a larger valued C5. I personally don't use bypass caps in this location and I believe the amp will work perfectly without it (Carlos might shoot me though).

p.s. nice country Malaysia, I've been a few times, and love the food.
 
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If 9x 1000uF capacitor, set in parallel ? or 4x 2200uF or 2x 4400uF ?
It is safe to make it bigger or smaller (capacitance) than the standard value ?
If all those capacitor i put into higher voltage rating, is it fine ? (hard to find exact 35V)

I just want it at 36V X.x not challenging high voltage !
 
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all three options sound good to me and a bit bigger or smaller should be fine. voltage rating of the capacitors should be higher than the highest dc voltage across them, for 36V rails you want 50V rated caps. The difference between the rated voltage of the cap and the voltage you will use them at is a margin of safety that allows for fluctuations in your power supply, manufacturing tolerances in your capacitors and generally speaking it prolongs the lifetime of the components by minimizing the stress placed on them.

the dangerous part is the mains voltage, you're on 240V in Malaysia if I remember so if you aren't sure of what you are doing please seek some advice if you are building your own power supply.
 
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all three options sound good to me and a bit bigger or smaller should be fine. voltage rating of the capacitors should be higher than the highest dc voltage across them, for 36V rails you want 50V rated caps. The difference between the rated voltage of the cap and the voltage you will use them at is a margin of safety that allows for fluctuations in your power supply, manufacturing tolerances in your capacitors and generally speaking it prolongs the lifetime of the components by minimizing the stress placed on them.

so as to say, voltage rating only means higher cost (most of the time) and doesn't much different if is within operating margin (lower than voltage rating) ?
Is it better to have the capacitors (in parallel) to be similar value (well... don't know, maybe more evenly distributed ?)
So i came out for below combination (also less number of capacitor & nearer to standard):
3300+2700+2700 = 8700
2700+2200+2200+1500=8600
and you tell me which is the best ? (with factor of spaces, heat produce, etc)
 
I don't think it matters which of these options you pick, it's not necessary for the values of capacitors in parallel to be the same - some people even say it's good if you have a range of different capacitors from large to small.

You can use capacitors with voltage rating of any value so long as it's above the voltage you will use them at but higher voltage rating is usually more expensive and the capacitor is bigger for the same value of capacitance. Some people have reported that higher voltage ratings, say 63V, sound better. I haven't tested that idea myself.
 
I'm kinda online purchasing those component, and i came across that saying of using polypropylene on small capacitor (1uF and below) will make sounds better ^^
according to this link (read the summary & table 1 is better... too long article to read thoroughly)
Picking Capacitors - Walter G. Jung and Richard Marsh
but the problem is that i found alot of those capacitors alot more voltage rating than my requirement (such as 630V, 2.2kV, 6.3kV), guess that doesn't matter ?
 
Man, i am very sorry as i am in outer space and i need to return earth

So long time passed and i cannot remember details about this amplifier...i am very sorry about it.

The output condenser controls bass response... the bigger will result in better low bass response (less losses)..the smaller will cut some deep bass tones (higher losses)... you can increase or decrease, depending what parts are available to you.... the lower the speaker impedance, the bigger the condenser should be.

Heatsinks you should calculate considering that an aluminium blade, 1 to 2 milimeters thickness, measuring 10 centimeter each side (square) will be good to a 10 watts amplifier (10 watts of audio, sinus audio ,undistorted, unclipped, continuous rms audio power...this is not consumption or heat...it is audio)... then so on.... 20 watts of audio power will need two of these blades, or equivalent area exposed to the air.

This amplifier really has the kind of sonics i love...it is not perfect, has some harmonics, a very old style unit....warm lovely sonics from my youth..i hope you will love it the same way i love it.

The good thing from these old style designs is the output coupled by capacitor, or electrolitic condenser in our amplifier... this blocks DC, so, everything can happens in the amplifier circuit without send DC to the speakers...when modern amplifier destroys speaker sending rail DC voltage to the speaker coils, this one can burn, short and melt and anything happens to the speakers....and this is absolutelly lovely.

About troubles we may have with condensers...well.... i do think it warms sonics that became more and more nice to my ears..... i remember that a good speaker brand, made in England in the seventies or eigthies, have used big condensers in series inside the speaker case....into the passive crossover, to control bass response.

I am doing other things and i have to land earth once again, to watch this amplifier schematic and think about it once more...i do not remember anymore.... i have made several other amplifiers and i cannot remember all them...not with 60 years old...i do not even remember what i had as dinner tonight!

regards,

Carlos
 
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