Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

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#2,564
Zen Mod said:
yes

soon to have finished (hopefully) last iteration, included limiters for driver buffer

it seems that I need to buy another fly swatter, to increase productivity; or to find 4hrs/day more





shorter one:


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Seems like a few of us are eager to get our hands on it. Please may I ask do you have a website or how do we order?

Trying to prepare the ancillaries before the board is ready, would the size be similar to the previous board or would it be vastly different? What is the VCC? I think you commented that it doesn’t go well with VCC below +- 30Vdc?
 
#2,565
working on version with additional limiter for buffer stage, so no smoke when overdriven

hopefully soon, as always ZM having several plates on the table, so slow .......... even if ZM Omniinevitable

no Trade threads for drekload of my amps and preamps, subconscious effort to leave more time for making new things, less time for Shyloking

time also being reason why I didn't wrote a dot in 4 years on my site

though, number of made ZM Omnithingies in same 4 years justifies that


so, whatever one need from ZML, simple PM is always enough
 
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#2,567
Mikerodrig27 said:
Here is the case. Maybe this link will work for a while. Attached is the description. It seems that there is one manufacturer of them and they get sprinkled throughout the resellers on both Ebay and Aliexpress. Aliexpress tends to have the better pricing.

I've built four amplifiers in that case. Attached is a pic of the 5u and aliexpress case in my workshop.

The case was perfect for the XA252. At max bias, the temp was just right. I believe around 25C above ambiant. If you look for my posts in this thread, I wrote a good amount about that amplifier.

As you noted, I'm using the aliexpress case with the F5mX. Right now I believe I have it at 60 watts a channel and it is sitting at around 25-30C over ambiant.

The stays more local on the 5U where the heat on the aliexpress case is more evenly distributed. The aliexpress is also very stout. Simple thick panels. One piece heatsink as opposed to two, chunky metal blocks holding the corners toghether. The top and bottom panels fasten diretly to the thick heatsinks. Also, the screws are larger... I also like the handles on the front.

The 5U cases can probably be custom drilled for the XA252. They are also a more plug and play solution where you will be drilling holes on the rear, the bottom, the heatsinks and if you want a swtich on the front, you will be drillling that as well. I do believe there is a version of the aliexpress case out in the wild that has a push button switch on the front. Also, the milling on the 5U case is a bit nicer in that sometimes the edges of the heatsinks are a bit rough on the aliexpress case. It doesn't bother me. If you want, you can knock them down and touch them up with a sharpie. The anodizing on the 5U case's heatsinks is more robust than the Aliexpress. The anodizing on the panels of the aliexpress's case are about the same quality of the 5U. The 5U has a rougher brushed finish.

The feet that come with Aliexprss are not bad but grab these if you can. They are nicer. Mount them close to the corners so that when you tip the case, the metal has less of a chance of hitting the surface under the amp.

Also, the front panel on the aliexpress case is some sort of sandblasted finish. I like it personally but people who want brushed would want a different case.

Okay, I may have written too much considering the XA252 is the topic of the thread. But hopefully this info will help some people.
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Please may I know what size is the heatsinks of your Aleph 2? 400 depth by 200 height on each side? adequate cooling? It is probably only 1/2 the amount of cooling area compare with the original?
 
#2,569
@Mikerodrig27 's Aleph 2 case, the Deluxe 5U Modushop 5U/400 case has 8,640cm2 per side for a pair of 200 x 200 x 40mm heatsinks.

The larger 5U/500 with a pair of 250mm long heatsinks has 11,300cm2.

Mike's (Qingfeng Studio = 清风工作室一店) 4320A has a 400 x 200 x 70mm heatsink on each side. I calculate total surface area of one heatsink (internal and external) is around 6,850cm2 and its base plate is thicker which may help with dissipation.

With the 4320A Mike #651 got:
a Delta of 25.1° which is about right on target.
Click to expand...
at a bias of 1.8A 126W whereas @Sorenm #2,514 found +30C in the Modushop 5U/500 with fans.

Does anyone else have figures?

Btw the Qingfeng 4820 case has a wider chassis (internally 380mm wide, 400mm deep, 192mm high) than the 4320A and closer 40mm fins, with a surface area of 8,350cm2. The heatsink's base plate is thinner.
 
#2,570
Well sadly the Maggie's were too much for the beautiful sound of the beastie. I had been using it mostly in the workshop on my test speakers and after remodeling living room it was time for it to take the roll it was designed for, about 20min in the doorbell rand and while I was answering it my wife said "somethings burning" = never good words to hear I shut it down as the left channel was dead
 
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#2,571
Giallograle said:
@Mikerodrig27 's Aleph 2 case, the Deluxe 5U Modushop 5U/400 case has 8,640cm2 per side for a pair of 200 x 200 x 40mm heatsinks.

The larger 5U/500 with a pair of 250mm long heatsinks has 11,300cm2.

Mike's (Qingfeng Studio = 清风工作室一店) 4320A has a 400 x 200 x 70mm heatsink on each side. I calculate total surface area of one heatsink (internal and external) is around 6,850cm2 and its base plate is thicker which may help with dissipation.

With the 4320A Mike #651 got:

at a bias of 1.8A 126W whereas @Sorenm #2,514 found +30C in the Modushop 5U/500 with fans.

Does anyone else have figures?

Btw the Qingfeng 4820 case has a wider chassis (internally 380mm wide, 400mm deep, 192mm high) than the 4320A and closer 40mm fins, with a surface area of 8,350cm2. The heatsink's base plate is thinner.
Click to expand...
thanks for the detailed calculation, it is unfortunate that made in China heatsinks do not come with any specs.

What is the optimal space between fins for optimal natural convection?

I once read somewhere it has to be wide enough to allow cool air in, but narrow enough such that the airflow is turbulence for maximum heat exchange between fins and the air.
 
#2,572
I need some help to find my THF-51S these insulating brushing, thermal pad and right size connecting terminal like these on the photo. I like to find them on Mouser. Maybe you guys have other ideas how to make thermal pad for Tokin and what to use for insulating brushing?

So far I do not have any luck browsing things in Mouser.

1738584341658.png
 
#2,573
Important revision of protection circuit:

Soldering resistor in parallel to diode in Optocoupler (OK1, OK2, pins 1-2), practically in parallel to LM385-1V2 (V1, V2), thus increasing protection threshold from intended 10Apeak;

So, choose - 100R across OK pins 1-2 shall elevate threshold by 50%; 47R across OK pins 1-2 shall elevate threshold by 100%, not-fitting both OK optocouplers and V1,V2 LM385 and TH1 Thyristor means no current limiting of OS at all; that option also viable

Said resistors can be anything - from tiny smd to 0207 size; power is negligible there

Reminder - all zener diodes right from Q3, Q4 (looking at schm in post #1) - value in range of 8V2 to 12V, whatever easiest to grab

Hope it'll help to contain Gray Smoke in bottle.
 
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#2,574
dBel84 said:
Well sadly the Maggie's were too much for the beautiful sound of the beastie. I had been using it mostly in the workshop on my test speakers and after remodeling living room it was time for it to take the roll it was designed for, about 20min in the doorbell rand and while I was answering it my wife said "somethings burning" = never good words to hear I shut it down as the left channel was dead
Click to expand...
Any idea what caused the failure? Have you really overdriven/clipping the amp. Or had the low impedance of the Maggie’s triggered the OPS protection, which caused an other event to happen?
 
#2,575
I think this relates to what zen just posted re protecting the circuit. It wasn't being driven hard, volume from pumpkin only at 9 o'clock (25%) but it was driven balanced while test set up was SE. Resistor R48 is charred, I need to find time to dismantle that side to access the board properly, anticipate some rebuilding. SIT, seems to have survived.
 
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#2,577
dBel84 said:
Well sadly the Maggie's were too much for the beautiful sound of the beastie. I had been using it mostly in the workshop on my test speakers and after remodeling living room it was time for it to take the roll it was designed for, about 20min in the doorbell rand and while I was answering it my wife said "somethings burning" = never good words to hear I shut it down as the left channel was dead
Click to expand...
Ahhh, the smell of burning R24 in the morning....sorry to hear this, I know the pain...I fried both channels by accidentally sending a large transient through it.
First channel repaired easy, second is giving some trouble, but I will get it.

Russellc
 
#2,578
Thanks for the update ZM.
My boards are assembled with ZD3&4 being 8V2 zeners and parallel 220R/opto mod.

If 220R is too much, I can parallel another resister on the bottom side to lower resistance.

Next step is to power up without pucks installed and measure voltage at locations from your annotated schematic.
 

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