I'm just in the middle of collecting all the aluminum, transistors, and other parts to needed to assemble my very first DIY amp, the Aleph 5. As a result of these efforts and alot of reading on this forum I decided to start the following thread for my own (and hopefully others) education and amusement. The top ten list I'd like to have us compile is to do with assembly practices and improved components. Not one particular amp design over another. I will starting the list here with one item and hopefully go from there.
1.) 1% metal film resistors?
Regards,
Dan
1.) 1% metal film resistors?
Regards,
Dan
Use twice as much heatsinking as you calculate you will need, and then leave out R-19 from the circuit all together. This should give you the best sounding Aleph you've ever heard!! This will bias the amp all the way up...at least as high as Q-5 will allow. Also, use lots of power supply capacitance and inductors if you can, and all Vishay resistors in the amp circuit. Nothing else in the circuit seems to make much of a sound quality difference as doing the R-19 removal. You might also want to just solder your speaker leads directly to the PCB insteading of wasting your $$ on designer banana jacks. Eliminating these usually makes for some improvement in sound.
Mark
Mark
I don’t think that resistor type (other than standards) is important (surely the “precision” predicate is not), but if it counts, how about using a non-polar feedback capacitor? (I usually put a series of 2 capacitors in feedback to make it NP. With my system, being forced to lower the value a bit had never harmed the low roll-off)
How about choosing the MOSFET? Will it be relevant to the topic? The IRF drives me crazy. I need a better high frequency. I have tried to increase the bias current, and also padded down the high frequency in the tweeter crossover, but still not satisfied. I’m collecting information to build the Aleph with 10N16/10P16 (2SK135/2SJ50 substitute). But because I have to buy them in complementary pairs, it may not be 100% Aleph.
How about choosing the MOSFET? Will it be relevant to the topic? The IRF drives me crazy. I need a better high frequency. I have tried to increase the bias current, and also padded down the high frequency in the tweeter crossover, but still not satisfied. I’m collecting information to build the Aleph with 10N16/10P16 (2SK135/2SJ50 substitute). But because I have to buy them in complementary pairs, it may not be 100% Aleph.
Dantwomey said......
"1.) Buy more heasinking and jumper R19."
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Am I missing something here? I dopn't see how jumpering R-19 would improve things. Removing it raises the current......in theory as high as it can go...according to the actions of Q-5. Changing things around Q-5 too much and then its not an ALeph any more.
Mark
"1.) Buy more heasinking and jumper R19."
_________________________________________________
Am I missing something here? I dopn't see how jumpering R-19 would improve things. Removing it raises the current......in theory as high as it can go...according to the actions of Q-5. Changing things around Q-5 too much and then its not an ALeph any more.
Mark
My 
1. Crank the bias up as much as you can manage.
2. Use a better power supply than what is shown in the service manual.
3. Use non-polar caps for the two 220uF caps.
4. Use a silver mica cap (or something similar) for the feedback cap.
5. Use whatever brand of exotic resistor you most prefer
6. Decrease the activeness of the aleph current source.
1. Crank the bias up as much as you can manage.
2. Use a better power supply than what is shown in the service manual.
3. Use non-polar caps for the two 220uF caps.
4. Use a silver mica cap (or something similar) for the feedback cap.
5. Use whatever brand of exotic resistor you most prefer
6. Decrease the activeness of the aleph current source.
IMO one of the most significant ways to improve over the standard design, specially if you have eficient speakers is to add a Pi filter on the power supply.
Originaly I had the standard bank of caps with 240Kuf which I thought was enough but had to add a CRC type of filter that greatly reduced the hum. The resistance selected was 4 x 3.3 Ohms in parallel, around 0.8 Ohms total, that droped my rails by about 6 Volts. So at this stage if you decide on some type of Pi filtering you might as well chose a higher secondary voltage for your trafo and revise the voltage rating of your first set of caps.
Reacently decided to add some inductors for a LCRC type of filtering on the PSU. The chokes will be high quality 23 mH good for some 3 Amps. Will post results.
Originaly I had the standard bank of caps with 240Kuf which I thought was enough but had to add a CRC type of filter that greatly reduced the hum. The resistance selected was 4 x 3.3 Ohms in parallel, around 0.8 Ohms total, that droped my rails by about 6 Volts. So at this stage if you decide on some type of Pi filtering you might as well chose a higher secondary voltage for your trafo and revise the voltage rating of your first set of caps.
Reacently decided to add some inductors for a LCRC type of filtering on the PSU. The chokes will be high quality 23 mH good for some 3 Amps. Will post results.
tweaky top ten...
My favorites without ranking – all important to reach the best sound:
- Diodes with low inner resistance and soft recovery – really a big step. Less harshness, more dynamic and transparency.
- Not masses of PSU caps, but high quality ones = lowest inductance, fast types. Bypassed with a e.g. 0,1UF MKP or FKP type – the sound improvement is amazing compared to this little bypass cap stuff…
- Inductance free power resistors, MOX like in speaker crossovers or metal strip ones, e.g. MPC71. This holds specially the contour of the music alive.
- Best coupling caps: expensive, huge foil types or – my reasonable tip – Panasonic FC Elkos 220UF 16V or 25V. They sound very fast, open and neutral. Spend an 10nF KP or MKP or FKP bypass and the loose last harshness. I compared them to 33UF MKP from Solen (the producer in France for almost all MKPs in Europe, like Mundorf, Audyn, …) – no chance for the fat monster. Somehow a bit intransparent and slow.
- "Hard electrical coupling" of parallel parts, like the FET bench or the speaker output resistor group or the PSU elkos. Hard means with low impedance = relatively high gauge. E.g. solder a rod of massive copper with <2,5qmm CSA on the thin and weak PCB track or use flying P2P. The sound becomes tighter and not washed.
I know it all sounds like I have lost my mind in tweaky drug stuff… But maybe first test it to know what it is about. If no difference can be heard frequently the improvement is hidden behind other stronger failures of the chain.
regards
Klaus
My favorites without ranking – all important to reach the best sound:
- Diodes with low inner resistance and soft recovery – really a big step. Less harshness, more dynamic and transparency.
- Not masses of PSU caps, but high quality ones = lowest inductance, fast types. Bypassed with a e.g. 0,1UF MKP or FKP type – the sound improvement is amazing compared to this little bypass cap stuff…
- Inductance free power resistors, MOX like in speaker crossovers or metal strip ones, e.g. MPC71. This holds specially the contour of the music alive.
- Best coupling caps: expensive, huge foil types or – my reasonable tip – Panasonic FC Elkos 220UF 16V or 25V. They sound very fast, open and neutral. Spend an 10nF KP or MKP or FKP bypass and the loose last harshness. I compared them to 33UF MKP from Solen (the producer in France for almost all MKPs in Europe, like Mundorf, Audyn, …) – no chance for the fat monster. Somehow a bit intransparent and slow.
- "Hard electrical coupling" of parallel parts, like the FET bench or the speaker output resistor group or the PSU elkos. Hard means with low impedance = relatively high gauge. E.g. solder a rod of massive copper with <2,5qmm CSA on the thin and weak PCB track or use flying P2P. The sound becomes tighter and not washed.
I know it all sounds like I have lost my mind in tweaky drug stuff… But maybe first test it to know what it is about. If no difference can be heard frequently the improvement is hidden behind other stronger failures of the chain.
regards
Klaus
Hi Klaus,
I noticed that you said "harshness" in your posting above.....After a 100 hour or so break in period I have yet to have any problems with harshness at all. In fact a major speaker designer visited my house a couple of weeks ago and thought the 2's were by far the best sounding amps he ever listened to. He will be building a tri-amped system for himeself using all Alephs in the near future. I wonder if the harshness could be that your speakers that might be excessively bright??? Also I've found there is definately a break in time on an Aleph to get where it sounds best. So I reccomend that you have to let the amp break in again each time you make a component change and then see what the effect is. Things seem to settle down in about 60 to 100 hours.
When I say R-19 I mean in the Aleph 2 and Aleph 5. Its a different R number in the 3 but the equivelent resistor in the 3 does the same thing. I think its alot higher value to begin with though. For the 2 or 5 I reccommend a 250K pot be inserted in place of R-19, and then you listen at different bias levels gradually working the bias up till you get the maximum drop across the source resistors. In my 2's thats just under .7 volts across the source resistors.
Regards,
Mark
I noticed that you said "harshness" in your posting above.....After a 100 hour or so break in period I have yet to have any problems with harshness at all. In fact a major speaker designer visited my house a couple of weeks ago and thought the 2's were by far the best sounding amps he ever listened to. He will be building a tri-amped system for himeself using all Alephs in the near future. I wonder if the harshness could be that your speakers that might be excessively bright??? Also I've found there is definately a break in time on an Aleph to get where it sounds best. So I reccomend that you have to let the amp break in again each time you make a component change and then see what the effect is. Things seem to settle down in about 60 to 100 hours.
When I say R-19 I mean in the Aleph 2 and Aleph 5. Its a different R number in the 3 but the equivelent resistor in the 3 does the same thing. I think its alot higher value to begin with though. For the 2 or 5 I reccommend a 250K pot be inserted in place of R-19, and then you listen at different bias levels gradually working the bias up till you get the maximum drop across the source resistors. In my 2's thats just under .7 volts across the source resistors.
Regards,
Mark
Hi Mark,
First thanks for your hints!
I just checked the dictionary for the vocabulary "harshness", it is not to good. I meant the more: shrillness, aggressive and somehow dull. This all IS NOT CAUSED by the Aleph! I can just agree, already with standard components and no tweaking this amp sound extremely good – specially regarding the missing of "harshness". But much more is possible, if the last rests of above mentioned properties are gone caused by "bad" components. Then the Aleph really takes off! I had the occasion to hear my DIY Aleph4 monos compared to a series production Aleph2. My amp made Music more neutral, because it really seems to be freed of last small bits of "harshness". And more transparency, contour and so on. The benefit of tweaking – exceeding the budget of series product producers.
I totally agree: after each small modification I listen for days, but IMHO 10h of "burn in" is enough. I am lucky to have no harsh or bright speakers. The opposite, AMT… Fantastic partner for dreams became true - by Pass Aleph gifts!
I will test the R19 story, but I fear my coolers will run into problems. Did I got you right: you utter following your tests, that the amp sounds better biased at maximum possible current, e.g. 0,55V vs. 0,7V on source R = idle +27% current. What are your experiences regarding the optimum strength of positive feedback to the current source by the RC-bridge?
Regards
Klaus
First thanks for your hints!
I just checked the dictionary for the vocabulary "harshness", it is not to good. I meant the more: shrillness, aggressive and somehow dull. This all IS NOT CAUSED by the Aleph! I can just agree, already with standard components and no tweaking this amp sound extremely good – specially regarding the missing of "harshness". But much more is possible, if the last rests of above mentioned properties are gone caused by "bad" components. Then the Aleph really takes off! I had the occasion to hear my DIY Aleph4 monos compared to a series production Aleph2. My amp made Music more neutral, because it really seems to be freed of last small bits of "harshness". And more transparency, contour and so on. The benefit of tweaking – exceeding the budget of series product producers.
I totally agree: after each small modification I listen for days, but IMHO 10h of "burn in" is enough. I am lucky to have no harsh or bright speakers. The opposite, AMT… Fantastic partner for dreams became true - by Pass Aleph gifts!
I will test the R19 story, but I fear my coolers will run into problems. Did I got you right: you utter following your tests, that the amp sounds better biased at maximum possible current, e.g. 0,55V vs. 0,7V on source R = idle +27% current. What are your experiences regarding the optimum strength of positive feedback to the current source by the RC-bridge?
Regards
Klaus
My list of the most effective techniques for getting the best sound out of an Aleph:
1) measure the linearity of each output transistor in addition to matching and use the most linear
2) bias the hell out of it, with overkill heat sinking
3) substitute in combinations of diff pair devices, picking the best performing ones in terms of distortion, noise, and sound
4) a good pi filter on the supply
5) power transformer two feet away
6) filter cap on reference Zener
7) a glass of fine Cabernet
8) better caps
9) better connectors and wire
10) better resistors
1) measure the linearity of each output transistor in addition to matching and use the most linear
2) bias the hell out of it, with overkill heat sinking
3) substitute in combinations of diff pair devices, picking the best performing ones in terms of distortion, noise, and sound
4) a good pi filter on the supply
5) power transformer two feet away
6) filter cap on reference Zener
7) a glass of fine Cabernet
8) better caps
9) better connectors and wire
10) better resistors
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