XELB said:
I know that store for many years but I don't go there for long years...
If it's the place I'm thinking, it's in Av. Madrid, right?
Are they open on saturday mornings?
Interesting.
Is that 2x35V?
That's too high, but the price is not bad at all.
2x30V at 250~300VA is what I need now...
It's in Almirante Reis. When you go from Areeiro to Alameda you cross a small garden. The shop is "in" the garden.
You can park the car in the garden and ask there for the shop.
(they don't have any outdors)
They still have a lot of prices in escudos and old things in stock. That's why some have really good prices
I saw 35V because a friend (expert in HIFI) tested LM's chips really hot. He said that they play better hot
I'am also awaiting for two STK401-290 chips(2x50W each 6/3 Ohms).
This one's I will bridge.
In the papper they look great, thats why I wont to test them with 2Ohm and 6Ohm speakers.
If I make an external regulated 35/33V PSU, I can use it for the two amps
You can park the car in the garden and ask there for the shop.
(they don't have any outdors)
They still have a lot of prices in escudos and old things in stock. That's why some have really good prices
I saw 35V because a friend (expert in HIFI) tested LM's chips really hot. He said that they play better hot
I'am also awaiting for two STK401-290 chips(2x50W each 6/3 Ohms).
This one's I will bridge.
In the papper they look great, thats why I wont to test them with 2Ohm and 6Ohm speakers.
If I make an external regulated 35/33V PSU, I can use it for the two amps
I have tried the unregulated snubberized PSU loud and clear at lunch time
Differences :
- more detail in high frequencies(guitars, voices, hithat, etc... all got better)
- Backing vocals and supporting instruments more detailed
- Bass seemed equal
( I have a little problem with bass, I am using an 125VA transformer as an test transformer
speakers only wake up when I give some "gas")
What I most enjoyed was discovering new sound that this amp couldn't reach.
I was listening and I was saying to my self, this instrument was not here…. Heheheh
Now a look forward to try the regulated
Differences :
- more detail in high frequencies(guitars, voices, hithat, etc... all got better)
- Backing vocals and supporting instruments more detailed
- Bass seemed equal
( I have a little problem with bass, I am using an 125VA transformer as an test transformer
speakers only wake up when I give some "gas")What I most enjoyed was discovering new sound that this amp couldn't reach.
I was listening and I was saying to my self, this instrument was not here…. Heheheh
Now a look forward to try the regulated
Well, after two weeks I can say that I like snubber more then plain LM338 regulated PSU.
Stage depth, details and bass are really improved. But there are some sounds, like a punch at the bongo's which are slightly different from LM338 in a bad way. They are not as much loud as they were with regulator and timbre is different. Whenever I do something with m GC's I try to listen to some of my reference materials which I know to the bone.
I made my snubber exactly as Carlos recomended, just haven't bypassed elco's at the chip (0.1u). Haven't had any left in a drawer. Will do this weekend. Hopefully. I haven't used MUR860. Instead I put MUR420.
Overall: A little of magic in highs that dissapeared after i put LM338 regs has been brought back with snubber. But I do have a feeling that sound is somehow compressed. I don't know how to express myself in another way.
It is important to say that with LM338 I've had exactly +/-24V (transformer is 2x21V), while with snubber I have +/-29V and we all know that sound of this chips changes with voltage too. So I can not speak about the same conditions anymore.
And Carlos already came with another interesting thing. Now I have to modify my reg. boards. Carlos, will you please take some vacation for a while. We need some time to try all this nice things.
Stage depth, details and bass are really improved. But there are some sounds, like a punch at the bongo's which are slightly different from LM338 in a bad way. They are not as much loud as they were with regulator and timbre is different. Whenever I do something with m GC's I try to listen to some of my reference materials which I know to the bone.
I made my snubber exactly as Carlos recomended, just haven't bypassed elco's at the chip (0.1u). Haven't had any left in a drawer. Will do this weekend. Hopefully. I haven't used MUR860. Instead I put MUR420.
Overall: A little of magic in highs that dissapeared after i put LM338 regs has been brought back with snubber. But I do have a feeling that sound is somehow compressed. I don't know how to express myself in another way.
It is important to say that with LM338 I've had exactly +/-24V (transformer is 2x21V), while with snubber I have +/-29V and we all know that sound of this chips changes with voltage too. So I can not speak about the same conditions anymore.
And Carlos already came with another interesting thing. Now I have to modify my reg. boards. Carlos, will you please take some vacation for a while. We need some time to try all this nice things.
shusha said:And Carlos already came with another interesting thing. Now I have to modify my reg. boards. Carlos, will you please take some vacation for a while. We need some time to try all this nice things.
I will go in vacations in July.
Meanwhile, lots of work for you.
Try the LM338 PSU again, it's quick and easy to put the snubbers on the output of the regs.
And don't forget to use 1,000~2,200uf+100nf caps on the chips, snubberized with 0.47R+47nf.
I have started my work in the regulated PSU
(because I was forced to do it.....)
My chip can only handle an 31.5V transformer!
My new toroid is 35V-340VA. I will have to regulate for 30V
I hope to finish this in the next few days for now, I am enjoying unregulated snubberized PSU.
If I could understand, before the caps near the chip I must use an 0.47R+47nf snubber.
Carlos, after the rectifier what values should I use, the same you advised?
(because I was forced to do it.....)
My chip can only handle an 31.5V transformer!
My new toroid is 35V-340VA. I will have to regulate for 30V
I hope to finish this in the next few days
for now, I am enjoying unregulated snubberized PSU.If I could understand, before the caps near the chip I must use an 0.47R+47nf snubber.
Carlos, after the rectifier what values should I use, the same you advised?
carlosfm said:
I Just asked because I will use this PSU for a different chip(that can only handle 45+/- V)
This PSU is regulated for how much output voltage ?
Lets see if I am correct:
I have an 340VA - 35V transformer, this will give aprox. 4,86 Amper in each rectifier... they will get hot
What should I buy, LM338T or LM338K STEEL ?
XELB said:This PSU is regulated for how much output voltage ?
It's on the schematic, isn't it?
XELB said:I have an 340VA - 35V transformer, this will give aprox. 4,86 Amper in each rectifier... they will get hot
What a confusion...
I think you mean 340VA - 2x35V, right?
The rectifiers have no problems with that.
XELB said:What should I buy, LM338T or LM338K STEEL ?
Whatever.
I use the LM338T.
carlosfm said:
I think XLEB was asking about max current handling, not max voltage handling. Yes the LM388T could handle 35VAC * 1.41 = ~50VDC.
But the question is, could it handle all the current that that the trafo is capable of sending its way?
35 x 2 secondaries means: 340VA/(2*35) = ~4.85 A (same result that XLEB got)
LM388T can handle continuous up to 5A and peak at 7A. So this means you will reach your trafo's max before you reach the LM338T's limit. As for heat, i have no idea.
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