Thank You Eivind . I'll look into changing orientation of board and placement of transistors but it may not be that easy. I'm rather into tubes and haven't touched SS for ages so keeping the layout as is how big is the risk of oscilations and is there any other way to prevent it ?I may drill holes in heat sink closer to the back and group transistors close to each other in each half if its going to help. Since the components were specyfied for 80V B+ the 58 v ac trans will be just fine (~81 V) and as Vincent suggested I can use 58v AC before rectifier for security stage . I hope thats doable.
Rgrds, L
Rgrds, L
No, this is truly the best amp in the world. Ive heard rumors that Nelson has one of these.
What matters is a Class of designer and design. Some will never give up their Naim amps for any A class. Also all chip clone amps are A/B (I think). I think all SS amps are junk compared to tubes but here I am
Now that's a whole different thread - let's not voice our opinions about SS vs Glass here.
It just seems that the VERY BEST amplifier has been modded and tweaked in just over 1900 posts. By definition, the very best cannot be bettered.
I'm itching for a new project and I'm just waiting to see if anyone has actually done any subjective tests between this amp and say the Pass Aleph J/X, which was supposedly one of Nelsons best amplifiers.
I'm itching for a new project and I'm just waiting to see if anyone has actually done any subjective tests between this amp and say the Pass Aleph J/X, which was supposedly one of Nelsons best amplifiers.
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Just reading the whole thread, I think I will be adopting my brother in laws Aleph 4 clone. IMHO that is the best amplifier that I have ever heard.
Nelson himself may well have tried one of these, but he never stands still. If there is a lesson to be learnt here I'm sure the F5 Turbo or its sucessor will adopt any improvements.
I don't want to hijack the thread so I will keep my opinions about Class A to their correct threads.
Nelson himself may well have tried one of these, but he never stands still. If there is a lesson to be learnt here I'm sure the F5 Turbo or its sucessor will adopt any improvements.
I don't want to hijack the thread so I will keep my opinions about Class A to their correct threads.
I think class-A is inherently better than class-B. But don't forget that you listen not only the amp but more importantly is the speaker. Just make sure that the amp, class-A or class-B, has no difficulty to drive the speaker.
For low power amp I still am okay with hot amp. But for high power amp (which I also need) I want class-B for the sake of electricity bill
.As for Goldmund:
(1) I want mosfet sound, and laterals (especially the Hitachi TO-3 ones) are better than vertical in class-B
(2) I want good drive for the mosfet, and Goldmund is very good at that (For 2-stage drive, JLH 82 is good, but not as good as 3-stage Goldmund).
(3) I want good or proven topology, and Goldmund topology is okay for me (of course I like SSA topology more, if the design works).
But I don't like the sound of most JFET amps (but most people like it may be because of the low noise), may be because the current is too low. And high current JFETs (K170, or the one used by Goldmund) are rare.
Above 10W or so there can't be too much difference as it's starting to get "loud".
Undoubtedly above 25W the Class AB, Class B and above come into their own.
Where the Class A is in its own league is at normal listening levels, unless you have no friends.
I started with a 30W Class A amp and the Aleph 4 at 100W Class A is definitely superior. Wether or not this was down to different designs we will never know. The 30 Watter did run out of steam at high volume.
If you chase the threads there is a strong contigent that just love the JLH and Hiraga 10W Class A designs.
The BEST Class A/B designs use Class A at the crossover point, what they do with the remainder of the power curve is what makes them unique.
Undoubtedly above 25W the Class AB, Class B and above come into their own.
Where the Class A is in its own league is at normal listening levels, unless you have no friends.
I started with a 30W Class A amp and the Aleph 4 at 100W Class A is definitely superior. Wether or not this was down to different designs we will never know. The 30 Watter did run out of steam at high volume.
If you chase the threads there is a strong contigent that just love the JLH and Hiraga 10W Class A designs.
The BEST Class A/B designs use Class A at the crossover point, what they do with the remainder of the power curve is what makes them unique.
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BIG.
It's not just the inductance of the wiring going back and forth, but also the proximity of the MOSFETs to the big heatsinks.
(aka Apoo made a real poo-poo of the GM, as bad as it gets)
OK, than what do you suggest? If I use L alu bracket on the back and position transistors to align with the holes on PCB and attach bracket to the back of chassis will there it be enough heat sinking in this arrangement? Regards, L
Well, There are only 6" (14cm) behind the board to fit transformer. In this chassis there is no other choice than
A) cluster transistors close together on both side of the heatsinks and hook it up with wire.
B) attach small L brackets to both sides of heatsinks with 3 transistors each and run the wires to the board.
There is no space inside to position the board any other way and fit transformer
except maybe positioning the board side way with transistors facing heatsink and using two small 200V-250 transformers on each monoblock or scraping the chassis and building a different one.
A) cluster transistors close together on both side of the heatsinks and hook it up with wire.
B) attach small L brackets to both sides of heatsinks with 3 transistors each and run the wires to the board.
There is no space inside to position the board any other way and fit transformer
except maybe positioning the board side way with transistors facing heatsink and using two small 200V-250 transformers on each monoblock or scraping the chassis and building a different one.
What i would do :
- rotate the board in the amp case, output stage facing the transformer.
- saw the output stage part of the board.
- Tilt it at a 90 degree angle off the main board.
- mount it on an L-angle (0.2" minimum thickness), other flange facing up.
- attach the L-angle to an aluminum square bar that fits like a glove inbetween the heatsinks (1.5" x 1.5" or preferably 2" x 2")
- attach the square bar to the heatsinks on both sides (threaded holes and allen bolts, or with a small bracket on opposite sides of the bar, plenty thermal paste)
Connections between both boards with drilled holes and wire links.
Refurbishing cost of $50-$75 tops. You could cover up the holes in the heatsinks with an alloy strip.
- rotate the board in the amp case, output stage facing the transformer.
- saw the output stage part of the board.
- Tilt it at a 90 degree angle off the main board.
- mount it on an L-angle (0.2" minimum thickness), other flange facing up.
- attach the L-angle to an aluminum square bar that fits like a glove inbetween the heatsinks (1.5" x 1.5" or preferably 2" x 2")
- attach the square bar to the heatsinks on both sides (threaded holes and allen bolts, or with a small bracket on opposite sides of the bar, plenty thermal paste)
Connections between both boards with drilled holes and wire links.
Refurbishing cost of $50-$75 tops. You could cover up the holes in the heatsinks with an alloy strip.
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hmmm, rotating the pcb is a good idea but you might not need to saw the pcb, just attach the L angle to the board attach the L angle to a square bar and attach square bar to heatsinks.
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Goldmund works perfectly and the sound is best I've heard.
I currently Aleph2, Aleph5, F5, F5balanced, AEM6500.
Goldmund 9.2 for me is the top.
Very fast, very balanced and superb dynamics with very good bass.
I do not get enough of it
We used all components after original scheme.
Goldmund is very stable.
I 3mV output;
bias - 90mA per transistor;
AC - 60V (+82 V,-80V);
DC - 70 V.
The picture signal to 1kHz,10kHz,100kHz.
Now working on the case, I'll come back with more results.
I want to thank very much to Nikos, Alex mm and Liliya for help and advice.
Thank you!
I currently Aleph2, Aleph5, F5, F5balanced, AEM6500.
Goldmund 9.2 for me is the top.
Very fast, very balanced and superb dynamics with very good bass.
I do not get enough of it
We used all components after original scheme.
Goldmund is very stable.
I 3mV output;
bias - 90mA per transistor;
AC - 60V (+82 V,-80V);
DC - 70 V.
The picture signal to 1kHz,10kHz,100kHz.
Now working on the case, I'll come back with more results.
I want to thank very much to Nikos, Alex mm and Liliya for help and advice.
Thank you!
Attachments
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