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Old 17th September 2012, 03:33 AM   #841
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Nice progress Bambadoo. The fuse may have saved your output transistors . Remember you had not set bias. Hope nothing else got damaged.
You could use a b1 buffer preamp between your preamp and amplifier. Although the preamp may sound dead silent by itself, any low level hum is further amplified by the
amplifier making it audible. Thats why when you cut the amplifiers gain, the hum reduced. The b1 buffer preamp might fix up this for you. Nelson Pass and diyaudio stock kits
for this buffer. Check to see whether your preamps voltage swing is safe for the buffer.
Take your time, you are making great progress. You may play with the amp , but dont mod it too much (this may change its character)
Attached are line level voltages Line level - Wikipedia, the free encyclopedia
Assuming your CD or source has 3v of output swing then pass this through the preamp for +18 dB gain, well ........it just doesnt work out
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Last edited by OnAudio; 17th September 2012 at 03:36 AM.
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Old 17th September 2012, 05:34 AM   #842
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Originally Posted by bambadoo View Post
... Extreme grip on the woofers....
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Originally Posted by bambadoo View Post
Yes I almost fainted when i played Lee Ritenour as the first note. Holy crap - I felt the bass note right in my guts..
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Originally Posted by bambadoo View Post
It is natural since this amp plays ridiculously good and I would like to be able to use it with my setup..
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Originally Posted by bambadoo View Post
Have been playing with the amp some hours now. The initial harshness in the upper regions seems gone. Suspect some burn-in time. Only beautiful music.

I have tried alot of amplifiers during my hifi - time.

This is maybe the first transistor amp I have tested that really grips the woofers and are very dynamic at very low volumes.
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Originally Posted by bambadoo View Post
Vocals seems vere "real" and I have not tried any classical yet..
Your almost there Bambadoo . Imagine having an exotic amplifier that you cannot buy from the shop currently and that you yourself have build. Looking forward to your review. Thank you for the time and expense that you are putting into this. Thank you for sharing your findings, these are important since we perceive sound uniquely. Is there a formula ?
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Last edited by OnAudio; 17th September 2012 at 05:38 AM.
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Old 18th September 2012, 03:33 AM   #843
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Originally Posted by bambadoo View Post
However - i Changed from RC to CRC in the psu just now.
Bridge rectifier - 2200uf - 7.5ohm (100w resistor) - 36000uf
Do you mean 0.75 Ohm ? , 0.075 Ohm ?

Remove the 2200uf and 7.5ohm and tell us the sound difference .
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Last edited by OnAudio; 18th September 2012 at 03:39 AM.
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Old 18th September 2012, 03:17 PM   #844
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Default Symef vs Symasym

Hi,

has anyone compared Symef with Symasym? What are the sound differences?
I have built just Symasym and searching if something can sound even better.

Thanks.
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Old 18th September 2012, 04:25 PM   #845
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Hi Kacernator, thank you for your query, the members will answer that for you. Joining us would be nice. Your input is important. The focus of this research is on real life like sound reproduction. You can read a few reviews here Gallery
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Old 18th September 2012, 04:47 PM   #846
routhun is offline routhun  United States
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Hi Kacernator,

Yes I built both of them, I haven't do a blind A/B test but I believe SYMEF is in a next level compared to SymAsym. Both have huge sound stage, but with SYMEF vocals and strings are amazing. Also the bass is tight and punchy with SYMEF. If you are looking for better than Symasym SYMEF is definitely worth a try.

Thanks,
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Old 18th September 2012, 04:47 PM   #847
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Quote:
Originally Posted by OnAudio View Post
Do you mean 0.75 Ohm ? , 0.075 Ohm ?

Remove the 2200uf and 7.5ohm and tell us the sound difference .
No I mean 7.5 ohm (two 15ohm 50w in parallell) - Reason is that I would be "safe".
2*35v trannie and with this setup i get 40.5V on the rails.

If I remove these my guess is approx 48Vdc on the rail.. Is that perfectly safe?

I have been playing a bit with Duncans psud designer for this...

The resistors do not get that hot.

I also have some inductors I could try but I have no idea if this is beneficial for this kind of amp.. (less ripple and so on)..

BTW: I have ordered dcb1 buffer

Thanks alot for advice. Read a couple of 100 pages here regarding it and could be what I need...


BTW::: Symef just keeps impressing me.. I have a hard time saying this but my tube power amp may get early retirement

And that is a really good one.
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Old 18th September 2012, 07:38 PM   #848
evette is offline evette  Canada
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I would take out the resistors the amp can handle 48 volts. Evette
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Old 19th September 2012, 04:18 AM   #849
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Originally Posted by bambadoo View Post
BTW::: Symef just keeps impressing me.. I have a hard time saying this but my tube power amp may get early retirement

And that is a really good one.
Its time we sent an amp to stereophile .
I am also interested to find out how it compares to some of the $250,000 amplifiers they have reviewed,
If the formula used on SYMEF is valid, there is a great likelihood SYMEF will come out ontop or they will be at par.

If however SYMEF is beaten to pieces the formula will be updated and we will have learned something new.
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Last edited by OnAudio; 19th September 2012 at 04:36 AM.
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Old 19th September 2012, 04:56 AM   #850
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Quote:
Originally Posted by OnAudio View Post
Its time we sent an amp to stereophile .
I am also interested to find out how it compares to some of the $250,000 amplifiers they have reviewed,
If the formula used on SYMEF is valid, there is a great likelihood SYMEF will come out ontop or they will be at par.

If however SYMEF is beaten to pieces the formula will be updated and we will have learned something new.
Let's be realist here... Even if this amp could beat a 250K amplifier, Stereophile would not be 100% neutral. The reason is simple... Those big companies pay a ton of money in advertising and it would be stupid from them to say that a DIY amplifier is beating one of their $$$ contributors.

I'm all for sending a unit there but without a brand they would not even review it I'm affraid... Maybe 6 moons?

Do
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