Tungsten - dumb question, what will that part do compared to the CL-60? Will it slow down and spread out the startup? Trying to understand what he desired outcome is with this part (guessing you want it slow, but not TOO slow...and once it has done its job it needs to not 'get in the way' of the power demands of the amp).
Yes, it reduces the inrush current and slows down the charging of the bank capacitors. More important with lots of capacitance being fed by a big transformer. There are several parameters that characterize NTC thermistors. The hot resistance is also good to know, as is the max current rating.
The CL-60 kind of got accepted as a default part, and it kind of works. There are better parts for the job. Mark started a good thread on this topic some time ago. Lots of good information there and some recommendations. That’s where I found the MS22 20005 NTC part.
The CL-60 kind of got accepted as a default part, and it kind of works. There are better parts for the job. Mark started a good thread on this topic some time ago. Lots of good information there and some recommendations. That’s where I found the MS22 20005 NTC part.
Sounds good, thanks! I'll assume others are using this part, so not just hypothetical.
Also, I have driven right by the Ametherm building in Carson City dozens of times, and looking on Google Street View, I think I actually remember looking at the logo and wondering what they did. Small world!
Also, I have driven right by the Ametherm building in Carson City dozens of times, and looking on Google Street View, I think I actually remember looking at the logo and wondering what they did. Small world!
The CL60 steady-state current is the same for 110 (120)V AC and for 220 (240)V AC implementation. Why? Because the 110 (120)V AC schematic uses two CL60's; the 220 (240) V AC uses a single CL60. Hence, the 110V AC splits the power (200W in the case of Aleph J) across two windings and two CL60's. Had to re-draw the power supply schematics to get my head around this - see attached.
My Aleph J draws a 4A constant current at 2 X 24.5V (my rails are sitting at between 24 - 25V loaded). So we arrive at 196W.
Taking into account the transformer losses, this real-life consumption on the secondary side translates to 215W / 240V = "only" 0.9A on the primary side. This is the "hot" current that runs through the thermistor at all times. The hot current range for CL60 is between 1.2A and 5A. So, it is slightly below what the specification sheet states is optimal.
The CL80 might be a better fit with its cold resistance of 47ohms and hot current nominal range sitting between 0.5A and 3A.
However, the CL60 will have a lower steady-state resistance at the steady-state current (0.9A), compared to CL80 - which means less dissipation & lower continuous running temperatures🙂
I'd say, with large capacitor banks (very large inrush currents) and tightly spec-ed transformer ratings (windings might start to buzz after a while, due to constant stress during power-on), maybe CL80 would be a better fit.
I would stay clear of CL90 (which has 120 ohms cold resistance).... especially with a non-symmetrical output stage like Aleph J. I'd start to worry about getting that non-symmetrical output stage as quickly a possible into nominal DC operating conditions (governed by the input diff. pair current and the CCS current) - to ensure the DC imbalance at speaker terminals stays close to 0. If this can't stabilise very quickly, there's a danger that the bass driver coil may start seeing some current running through it😱
This is an especially important consideration for those who bypassed C1 and removed the overcurrent protection transistor... all in the name of the purist approach and best sound.
Last edited:
It is a mistake to conflate vacuum tube amplifiers and mass market amplifiers with Nelson Pass designs that use industrial power Mosfets in the output stage.
what's wrong with tube ampliifers?
in majority of cases they have OPT, thus practically almost impossible to send DC to speaker coil
in fact, of 3 things you mentioned in post, one can be correlated with subpar quality ( mass market amps) while other two can't be correlated with issue of fried coils, in any way
for tube amps I wrote why
for Nelson's amps - there is no doubt in quality of his construction, but we are speaking here about our builds - varying through entire spectrum from utter drek to sublime ones ...... and that is having nothing with ruggedness of mosfet in OS
we are the Gremlins here ........
in majority of cases they have OPT, thus practically almost impossible to send DC to speaker coil
in fact, of 3 things you mentioned in post, one can be correlated with subpar quality ( mass market amps) while other two can't be correlated with issue of fried coils, in any way
for tube amps I wrote why
for Nelson's amps - there is no doubt in quality of his construction, but we are speaking here about our builds - varying through entire spectrum from utter drek to sublime ones ...... and that is having nothing with ruggedness of mosfet in OS
we are the Gremlins here ........
DC speaker protection
For an in depth review of the subject check out this link.
Loudspeaker Protection and Muting
For an in depth review of the subject check out this link.
Loudspeaker Protection and Muting
OK, of the 14 backordered items, I either found subs (matches the values, but also tried to match every other parameter where possible).
Here is where I am stuck, needing these (not sure of a good replacement). I put quantity next to them, as some have a few (but not enough). They also have long backorders. Only one electronic part, the rest are connectors and not sure what would be a good replacement. Appreciate the help!
1: CB4/2H Altech | Mouser
20: EV18-6RB-L Panduit | Mouser
20: DPF14-250FIB-M Panduit | Mouser
2: RFS-35V100ME3#5 Elna | Mouser
6: 39890-0303 Molex | Mouser
Here is where I am stuck, needing these (not sure of a good replacement). I put quantity next to them, as some have a few (but not enough). They also have long backorders. Only one electronic part, the rest are connectors and not sure what would be a good replacement. Appreciate the help!
1: CB4/2H Altech | Mouser
20: EV18-6RB-L Panduit | Mouser
20: DPF14-250FIB-M Panduit | Mouser
2: RFS-35V100ME3#5 Elna | Mouser
6: 39890-0303 Molex | Mouser
"Find Similar" is a great tool with Mouser. Also, as you go along, do your best to determine what the part is used for by referencing the build guide you got the BoM from, and any critical specs. You can also reference 6L6s guide (this thread) for physical connections he used.
1. Use - holds the ground lift thermistor. Is it used in 6L6's guide - no. Alternatives. Mount it to the chassis and the PSU board directly a la 6L6 or any suitable two-position (or more) block you like.
If you really like that model, then this is a slightly beefier model from the same manufacturer. You can compare the specs.
https://au.mouser.com/ProductDetail/Altech/CB6-2H?qs=RTnkMsGiivlJNniHbembQg==
2. Use - Various chassis connections. Is it used in 6L6's guide - sorta. Alternatives - Hit Lowes, HD, Amazon etc, and grab a box. These are very common. Note - they're color coded.
3. Use - Connections for PSU and IEC. Is it used in 6L6's guide - sorta. Alternatives - see above.
4. That's a tricky one. "Audio Grade" caps are a touchy subject. I'll let someone else with thicker skin suggest a part. Personally, I'd look for a low ESR cap from Panasonic or something from the Nichicon UKZ or UFG line as a cop out. There are also 3 different BoMs posted on the store site that offer alternative part numbers. I'd start with revision D and work back. One may hopefully be in stock.
5. This alternative comes up when using the "find similar" functions.
https://au.mouser.com/ProductDetail/TE-Connectivity/282836-3?qs=A%2Bip%2BNCYi6PbXzB92YbbqQ==
Really cool, Anand. Thank you for the effort and insight!
ZM: What circuit changes of yours would you say could help explain the subjective differences Anand has noted between the J and the J Zen?
Regards,
Andy
all my traces are circling CCW
good enough explanation?
well, poseidonvoice pretty much explained in his writing, mentioning few differences, but I know it is clear to me simply because I know what circuit exactly is
anyway, as said before, entire package is outa my hands, Mighty ZM as always left only with duty of helping here and there, so who is gonna publish schematic and what else of files, is not up to me
one day it will be published, entropy dictates .........
good enough explanation?
well, poseidonvoice pretty much explained in his writing, mentioning few differences, but I know it is clear to me simply because I know what circuit exactly is
anyway, as said before, entire package is outa my hands, Mighty ZM as always left only with duty of helping here and there, so who is gonna publish schematic and what else of files, is not up to me
one day it will be published, entropy dictates .........
CCW strikes me as the ultimate proper solution, obviously zeroing feedback effects and inverting distortion polarity
Babelfish not written on upper side, but trace pattern made in pattern of my most trusty Towel
Attachments
Last edited:
as I said before - not much Babelfishing, everything made to ease life (read - both assembly and setting procedure) of regular Greedy Boy, without loss of SQ comparing to original
so no biggie
major efforts invested in containing Mighty Myself to not go wild
so no biggie
major efforts invested in containing Mighty Myself to not go wild
You can imagine for me THE MIGHTY DELUSION of not having da BABELFISH logo on my front panel 
Live Long and 42
P.S. Out of spite I will put a towel inside!!!
Live Long and 42
P.S. Out of spite I will put a towel inside!!!
Where did you source the l-brackets for mounting the donuts?
I know you have limited twisting OCD, compared to some. Papa does too, ref to FW builds. However his bridges are always put at the back of the chassis. I think I am OK/good either way, but the two pics attached show two alternatives. Practically speaking, one bridge on each side of the tranny, is preferred, if distance to PCB is OK. Distance to first MOSFET measured to approx 7 cm.
The other solution, between trannies, is obviously the quietest, having all the worst ripple carrying wiring in one place as far away from sensitive stuff as possible, approx 20cm. But space is a bit tight.i could easily make it work though, and also there is room to move the trannies further from each other.
Why this challenge? Many, many caps. A proper BJ needs big caps