Pan,
Just curious if your ExtremeA amp is now up and running? Give us a feedback of the sound quality and performance based on your judgement or maybe a comparison on some of your DIY amp? I think everybody is interested of the outcome?
Just curious if your ExtremeA amp is now up and running? Give us a feedback of the sound quality and performance based on your judgement or maybe a comparison on some of your DIY amp? I think everybody is interested of the outcome?
It will take several weeks before initial testing will take place.
But I will report back. Measurements, subjective impressions and blind bypasstests. The bypass test will be performed in two ways.
1) A loop via the soundcard and amp driving a complex dummyload will be compared to the original using HD600.
2) ExtremA will be placed in a complete high quality two channel set up with controled acoustics. Listening will be performed via the speakers with and without ExtremA (driving a complex dummyload) in the chain.
This bypasstests makes more sense than just throwing the amp in a rig comparing it to another amp.
/Peter
But I will report back. Measurements, subjective impressions and blind bypasstests. The bypass test will be performed in two ways.
1) A loop via the soundcard and amp driving a complex dummyload will be compared to the original using HD600.
2) ExtremA will be placed in a complete high quality two channel set up with controled acoustics. Listening will be performed via the speakers with and without ExtremA (driving a complex dummyload) in the chain.
This bypasstests makes more sense than just throwing the amp in a rig comparing it to another amp.
/Peter
I am looking for heatsinks for the ExtremA.
Think i will go for the SK-533 from Fischer electronics.
Anybody any tips where i can find those, besides directly from the Fischer factory.
Regards
BTW. received the PCB's today🙂
Think i will go for the SK-533 from Fischer electronics.
Anybody any tips where i can find those, besides directly from the Fischer factory.
Regards
BTW. received the PCB's today🙂
@madrigal:
order them directly by Fischer if you could.
I've had always good experience with them - even custom made heat sinks are no problem, different lengths from what is printed in the catalogs won't be a problem too.
They're always very kind and help wherever they could.
order them directly by Fischer if you could.
I've had always good experience with them - even custom made heat sinks are no problem, different lengths from what is printed in the catalogs won't be a problem too.
They're always very kind and help wherever they could.
Just want to ask everyone, where did you buy your 18v or 22v 300VA - 500VA toroidal transformer? I tried parts express but only 250VA max. Can I connect two transfomer in parallel? Would that be possible? 
Hi Guys,
I've been wondering nobody had responded to my question maybe it sound stupid.
But anyway, I have another question. To those who assembled their ExremeA amp, where did you buy your Vishay J511/J510 and J505? I tried to buy these parts at mouser and other electronic stores and it's no longer available, can you guys recommend a store selling these current regulators. I am thinking of using CR470 and CR360 which would be a replica to meet the specs but also not available and expensive. Could I use 1N5314 replacement for J511 and 1N5297 for J505? I think it will work, it has the same function.
I'm just wondering if Pan's amp is now up and running? Never heard a feedback from him. Just curious?
I've been wondering nobody had responded to my question maybe it sound stupid.
But anyway, I have another question. To those who assembled their ExremeA amp, where did you buy your Vishay J511/J510 and J505? I tried to buy these parts at mouser and other electronic stores and it's no longer available, can you guys recommend a store selling these current regulators. I am thinking of using CR470 and CR360 which would be a replica to meet the specs but also not available and expensive. Could I use 1N5314 replacement for J511 and 1N5297 for J505? I think it will work, it has the same function.
I'm just wondering if Pan's amp is now up and running? Never heard a feedback from him. Just curious?
1N5283...1N5314 series should work fine.
An old Siliconix AppNote mentiones 2N4338...2N4341, J201/J202, 2N4391...2N4393 and J210...J212 as suitable "long-gate" JFETs for CCS (to be used with a source resistor to dial in the needed current). Some of those have lower Vds_max ratings than the 50V of the J500 series, then you'd need a series resistor to drop some voltage. Personally, I've been using dirt cheap BF244/BF245 (A, B and C grades) + resistor for CCS without any problems, but those are only 25V parts (like the J210 series)
And yes, you can parallel identically rated secondaries of a single transformer with dual, isolated secondaries, unless it is explicitely stated in the datasheet that you can't (I have never seen such, though), of course getting the polarities right. Paralleing secondaries across transformers is not recommended and probably forbidden by electrical codes anyway.
So, you'd have one tranny for each rail. One drawback, when you blow the primary fuse of one xfomer the other still is active, OTOH with the amp being a bridge design this is unlikely to cause any real desaster. To be safe, you might need to modify the relay driver circuit...
At any rate I would nonetheless prefer a single xformer, there should be ways to get a 500VA type...
- Klaus
An old Siliconix AppNote mentiones 2N4338...2N4341, J201/J202, 2N4391...2N4393 and J210...J212 as suitable "long-gate" JFETs for CCS (to be used with a source resistor to dial in the needed current). Some of those have lower Vds_max ratings than the 50V of the J500 series, then you'd need a series resistor to drop some voltage. Personally, I've been using dirt cheap BF244/BF245 (A, B and C grades) + resistor for CCS without any problems, but those are only 25V parts (like the J210 series)
And yes, you can parallel identically rated secondaries of a single transformer with dual, isolated secondaries, unless it is explicitely stated in the datasheet that you can't (I have never seen such, though), of course getting the polarities right. Paralleing secondaries across transformers is not recommended and probably forbidden by electrical codes anyway.
So, you'd have one tranny for each rail. One drawback, when you blow the primary fuse of one xfomer the other still is active, OTOH with the amp being a bridge design this is unlikely to cause any real desaster. To be safe, you might need to modify the relay driver circuit...
At any rate I would nonetheless prefer a single xformer, there should be ways to get a 500VA type...
- Klaus
Hi Klaus,
Thanks for your reply. I really appreciate it.
Almost all the specification of 1N5314 matches with J511 except the limiting voltage value of 1N5314 which is a little bit lower that made me doubt a bit. So that's why I ask for second opinion which now I feel more comfortable of using it.
In regards to the transformer, I'm planning to parallel two identical transformer with their primaries and secondaries, 0-18ac dual 250VA. I've just read the other day, after I posted the question, on an Aleph amp thread that this guy (cannot remember his name) paralled two transformer to achieve the VA requirement and it worked fine without any problem. So, I'm thinking that it will work too, which I probably have to gamble.
I tried looking for 0-18ac dual toroidal transformer with 300 - 500 va rating here in the US but no luck. It's possible to have it custom made but it will be more money and it will take a long wait. Rapid are selling those transfomers but it will cost me an arm and leg including the shipping cost, around $ 200.00. I might keep searching on the internet to see more options.
Regards,
Freddie
Thanks for your reply. I really appreciate it.
Almost all the specification of 1N5314 matches with J511 except the limiting voltage value of 1N5314 which is a little bit lower that made me doubt a bit. So that's why I ask for second opinion which now I feel more comfortable of using it.
In regards to the transformer, I'm planning to parallel two identical transformer with their primaries and secondaries, 0-18ac dual 250VA. I've just read the other day, after I posted the question, on an Aleph amp thread that this guy (cannot remember his name) paralled two transformer to achieve the VA requirement and it worked fine without any problem. So, I'm thinking that it will work too, which I probably have to gamble.
I tried looking for 0-18ac dual toroidal transformer with 300 - 500 va rating here in the US but no luck. It's possible to have it custom made but it will be more money and it will take a long wait. Rapid are selling those transfomers but it will cost me an arm and leg including the shipping cost, around $ 200.00. I might keep searching on the internet to see more options.
Regards,
Freddie
Hi Freddie,
that Siliconix Note says max voltage for the J500 parts is at least 50V (going up to 100V), while the MicroSemi DS for the 1N4314 says 100V (which also fits to the max dissipation rating of 500mW, with the 5mA nominal current). Since the rail-to-rail voltages in the ExtremA are less, this should be safe. The J511 (U1) for LED bias sees the highest working voltage, which is on the order of 50..60V at most. The others see only 15V, if got that PSU schematic right.
- Klaus
that Siliconix Note says max voltage for the J500 parts is at least 50V (going up to 100V), while the MicroSemi DS for the 1N4314 says 100V (which also fits to the max dissipation rating of 500mW, with the 5mA nominal current). Since the rail-to-rail voltages in the ExtremA are less, this should be safe. The J511 (U1) for LED bias sees the highest working voltage, which is on the order of 50..60V at most. The others see only 15V, if got that PSU schematic right.
- Klaus
Thanks Klaus for your input, that helped me more understand the part. The J511 is the one that hold me on buying parts for ExtremeA since its no longer available for per piece purchase. Theres still a lot of store selling it but you have to buy it by the hundreds. Now with this alternative part that I can use, I can start buying parts. For sure it will take a while before I get this thing completed since I'm doing it only on my spare time.
I'm just curious how it sounds since nobody in this thread made any comment. Silence means, " yes it's awesome!!!"
What do you think Klaus? Did you give it a shot? 
Freddie
I'm just curious how it sounds since nobody in this thread made any comment. Silence means, " yes it's awesome!!!"
What do you think Klaus? Did you give it a shot? Freddie
Transformers
Hi fredlock,
try http://www.schuro.de/
They have high end transformers @
http://www.schuro.de/preisl-v-rkt-ms-sw.htm
You can order them at any voltage ratings (for 6 EUR).
I haven't used them but I think the 800VA type is just the thing you need.
Best regards,
RolMar
Hi fredlock,
try http://www.schuro.de/
They have high end transformers @
http://www.schuro.de/preisl-v-rkt-ms-sw.htm
You can order them at any voltage ratings (for 6 EUR).
I haven't used them but I think the 800VA type is just the thing you need.
Best regards,
RolMar
fredlock said:
Use a 250VA/Rect. for the positive rail and another 250VA(+ bridge rect.) for the negative one.
Maybe cheaper, some even prefer it that way.
Thanks RolMar for the link. That's a nice site to buy electronic stuff. The only problem is I don't understand the language. 🙄
Thanks Jacco for the tip. I will for sure do that since I don't have any choice. Buying those transformer out of the country is killing me. The shipping cost is almost the same as the price of the trafos.
Thanks Jacco for the tip. I will for sure do that since I don't have any choice. Buying those transformer out of the country is killing me. The shipping cost is almost the same as the price of the trafos.
All things relative, shipping costs for ordering bulky stuff from California or Canada is just as painfull from this end, overhere even the mailing ticket receives a 35% sales and import tax surcharge.
Indeed a nice shop, 15 years ago it offered OPA627/637 and LT1028 at half the rate that was charged by the single supplier overhere, and without the requirement to buy a minimum (+uneven number) quantity.
It surprises me to see so many bite the bullet.
Assembling this amplifier for a lower continuous output power level would make logistics and thermal issues a lot easier.
A 250VA would be enough for a 50W/8 version, and a 0.25-0.30C/W heatsink is easy enough to find.
(not as much fun as superchargin though, like this one, as used for the A'd GB50d, <<0.1C/W )
Indeed a nice shop, 15 years ago it offered OPA627/637 and LT1028 at half the rate that was charged by the single supplier overhere, and without the requirement to buy a minimum (+uneven number) quantity.
It surprises me to see so many bite the bullet.
Assembling this amplifier for a lower continuous output power level would make logistics and thermal issues a lot easier.
A 250VA would be enough for a 50W/8 version, and a 0.25-0.30C/W heatsink is easy enough to find.
(not as much fun as superchargin though, like this one, as used for the A'd GB50d, <<0.1C/W )
Attachments
fredlock
Try www.plitron.com for the transformer. Here is the link
http://www.plitron.com/shopping/shopexd.asp?id=183
This is where I'll be getting my tranny once I get the PCBs to build the ExtremA.
Also try http://www.sayal.com/ for J511 part. I know they have them.
Good luck.
Try www.plitron.com for the transformer. Here is the link
http://www.plitron.com/shopping/shopexd.asp?id=183
This is where I'll be getting my tranny once I get the PCBs to build the ExtremA.
Also try http://www.sayal.com/ for J511 part. I know they have them.
Good luck.
Thanks once again for the tip. I will be building this amp and the F5. I will compare them on the sound quality but unfortunately, I cannot make the comments here since it will be unfair to both designer. I will keep it confidential and the judgement will depend on my sonic taste. It's the same thing on food, sometimes you like it more saltier and others prefers it less salt.
Thanks Vadim, good to know about that store that still sells J511 in retail. I haven't been to that site yet but I'll try it later today.
Thanks Vadim, good to know about that store that still sells J511 in retail. I haven't been to that site yet but I'll try it later today.
Hi Vadim,
I checked that site, http://www.sayal.com/, and didn't find any J511. Can you post the full link location of that part? If you're getting it from another site, then let me know. If no luck then, I'll just use the alternative diode mentioned above.
Thanks.
I checked that site, http://www.sayal.com/, and didn't find any J511. Can you post the full link location of that part? If you're getting it from another site, then let me know. If no luck then, I'll just use the alternative diode mentioned above.
Thanks.
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