I finished my Aleph 60s mono amps today. I took these numbers after the amp was on for an hour, but haven't adjusted any pots yet, nor done anything with the AC gain. Do these numbers look ok?
Each mono-block actually contains two different amps. On one heatsink is the main Aleph board, and on the other side is the expansion board and a Modulus 686 class AB amp. I used Deluxe 5U stereo chassis' and combined the boards because they both take the same PS rail voltage. Each amp board has its own line input and speaker output on the back, and for now I manually switch the power supply outputs from one board or another, until I get a beefy switch for the back that will do it instead. I used soft-start boards that I had for the class AB amp, so I didn't install the little CL60 AC cap boards. I am planning on using the Aleph 60s with Klipsch Forte II speakers, and the 686 with my Avalon speakers (I swap between the speakers every six months or so), but maybe the Aleph 60 will also drive the Avalon's.
I have been listening to the Aleph 60's while writing this post. They are sounding very, very good, even though they have only been powered up for a couple of hours total. I would like to express my appreciation to rhthatcher and others who contributed to the project, and of course to Nelson for all the great designs we've been able to build and listen to. The outstanding build guides and BOMs and other documentation for this project allowed me to keep my stupid questions to a minimum.
Now I have to clean up the mess before my spouse comes down to the basement.
Alan
Each mono-block actually contains two different amps. On one heatsink is the main Aleph board, and on the other side is the expansion board and a Modulus 686 class AB amp. I used Deluxe 5U stereo chassis' and combined the boards because they both take the same PS rail voltage. Each amp board has its own line input and speaker output on the back, and for now I manually switch the power supply outputs from one board or another, until I get a beefy switch for the back that will do it instead. I used soft-start boards that I had for the class AB amp, so I didn't install the little CL60 AC cap boards. I am planning on using the Aleph 60s with Klipsch Forte II speakers, and the 686 with my Avalon speakers (I swap between the speakers every six months or so), but maybe the Aleph 60 will also drive the Avalon's.
I have been listening to the Aleph 60's while writing this post. They are sounding very, very good, even though they have only been powered up for a couple of hours total. I would like to express my appreciation to rhthatcher and others who contributed to the project, and of course to Nelson for all the great designs we've been able to build and listen to. The outstanding build guides and BOMs and other documentation for this project allowed me to keep my stupid questions to a minimum.
Now I have to clean up the mess before my spouse comes down to the basement.
Alan
Gulp, I'm not anal retentive, but that room would bring out the Monk on me.... MONK, MONK, MONK....
Aljordan,
Your numbers look good. Offset is spot on. MOSFETs share the load evenly. Bias is good.
Did you set AC gain to 50%?
How’s the heat after a few hours? I imagine it’s not too bad since you’re running in a 5U. You might be able to crank up current if you like. If you have clamp type meter you can measure current on the positive or negative rail PSU wire in seconds as you set it.
Your 2-in-1 build is very clever! Well done!
Your numbers look good. Offset is spot on. MOSFETs share the load evenly. Bias is good.
Did you set AC gain to 50%?
How’s the heat after a few hours? I imagine it’s not too bad since you’re running in a 5U. You might be able to crank up current if you like. If you have clamp type meter you can measure current on the positive or negative rail PSU wire in seconds as you set it.
Your 2-in-1 build is very clever! Well done!
I have not yet set AC gain to 50%. I will try to do so today, but I am a little worried about it. Back when I made the BOM orders, there were no 50k multi-turn trim pots available from any of the usual places, so instead I used some extra 50k single turn trimpots I had left over from a biamp 6-24 crossover build. I was able to get the initial setting correct prior to soldering them in, but they are very touchy. I am worried that they may be too touchy to set accurately.
I felt the heatsinks after five hours of listing last night. They were hot compared to my other amps, but I could leave my hands on them indefinately without feeling discomfort. What current level would be a good target?
At some point (in the winter when the extra heat will be welcomed), I will probably remove the 686 boards and convert the amps to dedicated Aleph 2 monoblocks to see what the extra oomph gives me.
P.S. tonyEE, the room is much better looking today. A magical transformation.
Alan
Alan,
Aleph 2 runs higher rails at 3A. So you're in the 2.2 range now... Try 2.5, 2.75, 3.0. See what difference it makes to the sound. The 5U can take 3.0A at the higher rails in Aleph 2 mono configuration, so you're good to go for cranking it up a bit.
You can measure the AC Gain without touching that single turn pot. See what you have. I know those single turns take very delicate handling to do minor adjustments...
Aleph 2 runs higher rails at 3A. So you're in the 2.2 range now... Try 2.5, 2.75, 3.0. See what difference it makes to the sound. The 5U can take 3.0A at the higher rails in Aleph 2 mono configuration, so you're good to go for cranking it up a bit.
You can measure the AC Gain without touching that single turn pot. See what you have. I know those single turns take very delicate handling to do minor adjustments...
So it turns out that my single turn pot is the current adjustment pot, not the AC gain pot. I did the "set current gain" procedure, and both amps were quite bit off. The left amp was at 66 mV where it needed to be at 102. The right amp was at 84 mV where it needed to be at 105.5. I was able to set them at 102 and 105 respectively. My multimeter wasn't giving me mV decimals on the AC reading, so hopefully accuracy down to the mV is ok. I rechecked DC offset after and it was fine. Do I need to recheck the current at the source and output mosfets, or should they still be relatively proper?
Thanks,
Alan
Thanks,
Alan
Alan, you should be good to go. Do you notice a sonic difference with the AC gain pot adjusted?
Enjoy the music!!!
Enjoy the music!!!
Thanks,
Yes I do notice a difference. It is firmer in the bass and more dynamic (snappy) sounding on some music, yet still retains good smoothness after it warms up. Very 3D. (Though I hadn't had the amp for a day yet, so I didn't have a great feel for how it sounded before.)
The Aleph 60 is a little sizzly sounding when I first turn it on, but sounds very good after it heats up a while. Out of the many amps I've built, my favorite into the Klipsch Forte has been the Aleph J. There is a subtle beauty to the combo which seems like the Aleph J's are gently asking the speakers to play beautiful music for them, and the speakers say, "but of course we will, we love you". The Aleph 60 seems like it is telling the drivers - in no uncertain terms - what they damn well better do. Lots of grip in the bass, and an exciting and lively 3D presentation. Spooky good at times.
One more question: if I start playing with the current setting, should I readjust the AC current gain after? What does increasing the current tend to do to the sound?
Thanks again,
Alan
The Fortes are 95 db/watt, huh?
Chez moi, the A2s are spanking the A5 all over the map and it's not even subtle... but I drive Maggies so I need the power and the A2 have a lot of control over the bass, as if I had powered up the Entec woofers. I got those Rat Shack APM-200 power meters and at reasonably sound levels I see the 50 wpc LED fully turned on! The soundstage is solid, instruments are located firmly in space, the Maggie Bass Slam is out in full display, albums I've owned since the mid 70s now reveal detail that I never knew, even when playing out, you can hear the bass lines, the metallic shimmer of the crash cymbal.... the only difference here is the amp, mind you. Main difference in sound is that the A2s do this when playing loud while the A5 required a more polite sound level...
With the A2, the music over my Maggie 1.7s is beyond spooky, it just sounds like the stereo is not there. With the A5s, vocal, bluegrass, acoustic and some smaller rock and orchestral reached that level, with the A2s you can play Frampton Comes Alive and suddenly you got a late 1970s live concert in your room. The Beatles, Blue Album, play the 4th side.... Go play While My Guitar Gently Weeps and HEAR the guitar. I have dynamic range now.
Mostly, my comment, is a matter of power and your needs. Will an A2 sound as good over the very efficient Klipsch's as the lower powered 60?
You're likely just be putting out 10 wpc max... (*) If you change your amps to a full time A2, will you lose something when playing over the Klispch?
I realize that these are all Class A... so the first watt should sound as good as the 100th watt, but is this true? Are these amps designed to work best at specific power ranges? From my experience, using the APM-200 power meters, the A2 playing as the same level as the A5, in the 10 watt range, just has a better presentation, deeper bass.... those reserves of power seem to matter. But, if you played those amps in the 1 watt range with an efficient speaker, would the lower powered amp actually sound better because it would be in its sweet spot while the higher powered amp was simply "not awake" yet?
BTW, both my A2s and the A5s share the same (re) builder so there's an commonality in there so I figure the difference is in the amplifiers power and design differences.
(*) Unless you play Hoff... in which case, God Help You.
Oh, yeah, builder's thread....
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I don't think I would lose something via the Klipsch, but I would have to remove the 686 and then might possibly lose something into the Avalons. The Klipsch are my most efficient speaker, but I believe the impedance dips down to 3.6 ohms in some area of the midbass. The Aleph 60 sounds quite a bit better into the Klipsch than the 686 (my personal preference of course).
The Avalon's are 87 dB with a 5 ohm nominal load. The woofers are tough to control. They generally sound loose and flabby in the bass via class A amps (I haven't tried any higher powered class A into them other than the Pass XA100.5 monos, which were beautiful sounding but still didn't control the bass well enough). The Avalon bass sounded amazing with class D amps, but I didn't like the sound of the higher frequencies. I guess I am too picky. I can get quite good sound from the 686 into the Avalon's. I'll try the A60 and see how they do.
I was just wondering how more current generally sounds. I am guessing it gives more driver control when the impedance gets tough. Does all that power corrupt the higher frequencies?
it would be interesting if an amplifier could be built with a front panel switch that controlled the power... perhaps the bias? Vcc? Something like the old STASIS model but with the power supply rail selected statically from the front panel... say three levels... low, mid and high. I figure that would also affect the current?
Experiments.... I have a Conrad Johnson MF2100 solid state AB amp. According to the factory it puts out an honest 100/200 wpc into 8/4 ohms. It has good bass into the Maggies but it misses the midrange and the treble magic. I mean it sounds very good but it just not the same. Not as convincing.
I also have a pair of Acoustic Reality ICE amps. 100/200 into 8/4 ohms. Awesome bass for sure, but as you note, soft in the treble.
Next up I just ordered a case for my NC252MP NCore amp board... same rating, will see, I think it will be much cleaner than the A2 but I think it will also be boring.
All of these are "high current" amps, so they do bass quite well. The ICE amps, have an iron grip. the NCore amps are supposed to be the same -or better. The A2 do the best, so far, Maggie Bass Slam though.
I got other things, all fully rebuilt or almost new... the Marantz 2325 drives the speakers but the lights dim on loud transients... the Sansui G7500 just doesn't cut it, even though it's rated at 90w into 8ohms.. so it should at least do something. A Nuforce STA200 does OK, but not loud and it gets pretty hot... ooops.. and so on.
Given that my amps shared power ratings, I have to note that the more current they can drive, even when rated at the same level, they better they sound. The more the soundstage stays put without shrinking as loud transients come along. But this is into the same speakers, Maggies, which are a cruel load.
I have another set of speakers in the living room, my vintage ADS L810s, I'm their only owner, but those things are so efficient that the DIY F5 drives them to satisfying levels... and the A5s are overkill, besides, they are vintage and they sound good, but the soundstage is not modern. And I'm not going to trudge the main HT speakers, PSB Goldi' MkII into the living room to test my theories.
I would think, if I were you, I'd leave your new amp as it is (*) and build yourself an A2 from scratch. use the black chassis with the handles, the front panel switch and a blue LED.
I've been toying with the idea of asking You Know Who to build me an F3 Turbo V3 if he has the time and the inclination, but for that I really want a front panel old fashioned power meter... round with a black bakelite finish, about 3 inches, round. With WHITE light!
(*) Did you forget to put a BLUE LED on the front panel? OMG!
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I tried the Aleph 60 with the tougher-to-drive speakers. At the standard current setting, the speakers sounded like they had some cloth over the drivers; fairly unresponsive. I increased the current about 0.2 amps, and I noticed a little change, so I cranked the current up to about 2.7 amps, which is about as far as the pot allows. Heatsinks were still fine. The sound freed from the speakers much better, and the amps actually controlled the bass well (very punchy), but they sounded very bass heavy.
I rechecked the AC gain figures, and they were way off at the higher current. Problem is that the range of the AC gain pot doesn't allow you to get near the proper value with the current cranked that high. I was only able to get to a proper AC gain setting when I backed the current down to about 2.5 amps. The amps still sound a bit dark into the speakers, but it is a rather beautiful sound nonetheless, and I don't feel like dynamics are suffering.
I will see if the amp still sounds as amazing into the Klipsch at the higher current setting. If so, then I imagine it will be worth a try to convert to Aleph 2's come winter.
Thanks for the advice.
Alan
Hotrod Aleph 30? Where is my Aleph 40?
I am enjoying my Aleph 30 since a few months now and i love it. I use a 4U 300mm Dissipante / Deluxe enclosure and it runs pretty hot - too hot for my taste. Today i ordered a 5U 400mm enclosure, that should have nearly double the heat dissipation capacity compared to 4U 300.
I also want to restore my M2x that was housed in the 4U 300 box before. To be able to use both amps simultaneously I need:
My goal is to get more power while achieving a cooler chassis. I think 150W total dissipation per channel should be fine with the 5U 400.
The Aleph Power Spreadsheet I mentioned before calculates around 55°C heatsink temperature for a dissipation of 165 Watts per channel, all thermal conductivity values have been down rated for safety, assumed ambient temperature is 28°C. This calculation is based on a rail voltage of 30V and a quiescent current of 2,7 A.
Coming from an Aleph 30, what values have to be changed to go to 8 MOSFETs per channel instead of 6? Do I have to change the value of the FET bias resistors? What would I have to change to use more quiescent current? Any hints?
I am enjoying my Aleph 30 since a few months now and i love it. I use a 4U 300mm Dissipante / Deluxe enclosure and it runs pretty hot - too hot for my taste. Today i ordered a 5U 400mm enclosure, that should have nearly double the heat dissipation capacity compared to 4U 300.
I also want to restore my M2x that was housed in the 4U 300 box before. To be able to use both amps simultaneously I need:
- new power transformer(s?)
- a new PSU PCB (I should have a spare F5TV3 PSU PCB)
- Maybe a new Set of 2x8 MOSFETs to spread the heat more evenly on the split heatsinks of the 5U 400
My goal is to get more power while achieving a cooler chassis. I think 150W total dissipation per channel should be fine with the 5U 400.
The Aleph Power Spreadsheet I mentioned before calculates around 55°C heatsink temperature for a dissipation of 165 Watts per channel, all thermal conductivity values have been down rated for safety, assumed ambient temperature is 28°C. This calculation is based on a rail voltage of 30V and a quiescent current of 2,7 A.
Coming from an Aleph 30, what values have to be changed to go to 8 MOSFETs per channel instead of 6? Do I have to change the value of the FET bias resistors? What would I have to change to use more quiescent current? Any hints?
Maybe my last post was a bit longish.. Few days ago I messaged Randy to ask him for some opinions about the Aleph 40 project. Luckily he is very interested in creating an Aleph 40 buildguide for a 4+4 MOSFET configuration (instead of 3+3 in a A30 build). We aim for at least 40W power into 8 ohm and hopefully around 65W power into 4 ohm.
Randy offered his help and a set of boards and parts for this build (thanks again!). So now I am starting to gather some parts for the dual-mono PSU with two 400VA / 22 VAC donuts.
Don't expect me to finish my build next week. But I want to finish the build and documentation before the end of this year.
Randy offered his help and a set of boards and parts for this build (thanks again!). So now I am starting to gather some parts for the dual-mono PSU with two 400VA / 22 VAC donuts.
Don't expect me to finish my build next week. But I want to finish the build and documentation before the end of this year.
Interested in your developments Addidub. I’m in the process of building my Aleph30+. My dual mono SLB psu will feed approximately 28-29vdc (loaded) which is right in between Aleph30 and Aleph5. Hoping for output in the 40’ish watt @8Ohm range. I am also interested in the 4+4 configuration, but if adding the additional pair of mosfets will be most beneficial for 4R speaker loads, that probably will not help me though. Still lots to do, but in no hurry to add a room heater during the summer months
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Vunce, that looks great! As the SLB is a capacitance multiplier the voltage drop will be not as high as with Randy's V8 CRCRC boards. So I am optimistic that you will reach 28 - 29V under load with your 20V transformer. With Randy's help I decided to go for 22V transformers - I hope to to get 29V - 30V under load. Let's see..
To achieve 40W into 8ohm I think 30V rail voltage is the minimum. My speakers are 4R so I am more into increasing the quiescent current (2.8A - 3.1A per channel) to achieve more power into lower R loads.
I'm so excited to see how these 4+4 Aleph ~40's come out! It's exciting that AddiDub will be the trailblazer and then Vunce might go for an upgrade.
@Vunce - your dual SLB stacked over donuts is totally cool - well done!
The SLB will have a higher voltage drop than CRCRC based on the cap multiplier. I'm very curious to see where the 24V Donuts / SLB vs. 22V Donuts with CRCRC come out for rail voltages in the real world.
@Vunce - your dual SLB stacked over donuts is totally cool - well done!
The SLB will have a higher voltage drop than CRCRC based on the cap multiplier. I'm very curious to see where the 24V Donuts / SLB vs. 22V Donuts with CRCRC come out for rail voltages in the real world.
I am down to 1 of these boards in my box of boards, so it's time to order more. I have made a few changes and want to get input from @Plott and any others in 220/240VAC regions. See Post 273 and the following few posts for more detail.
Changes:
- rounded corners
- added "120VAC Hookup" label on one side
- added silkscreens on other side to reflect 220/240VAC hookup with only 1 CL-60. Based on Plott's drawing above.
See Pix. Any feedback?
