Hello,
I have bought lm3886 amplifier as a finished product from Denmark.
Concept.... input relay, potentiometer, lm3886amplifier.
power supply... From +-/38V regulated with 337/317 and TIP35/36 to +-/28V
Sound is so so...It is to sweet sounding. Bas is good midrange iz sweet but to soft and treeble is ...to plastic. Every kind of music has the same tipe of sound...no nevtrality. source pc-jriver-SUBBU DAC
I know that a lot of you have done this amplifier and I will kindly ask If anybody have any MODIFICATION RECOMENDATION.
I think to build in TUBE BUFFER with 12au7 or ecc88 or max gain of 2-4 and lower gain at lm3886 to 10-15. Have anybody experimented with lower values of resistors insted 22k-1k....2k-100R or with sound of gain 30 Vs gain 10. My friend have made some listening tests and say that with lower gain sound is better and less noisier, but is problem that with low output source gain could be to low.
What about volume poti. Is it better to have it in front of tube preamp or behind buffer preamp. I would like to have it after buffer, because at lower pot position you also get less noise. If poti is in fornt of tube preamp al noise get directly to amp. I have read that distorsion is higher with poti at the end of a tube preamp???
Her are some schematcs from AMPLIFIER and tube preamp-buffer suggestion.
You are welcome with ideas. Thank you.
I have bought lm3886 amplifier as a finished product from Denmark.
Concept.... input relay, potentiometer, lm3886amplifier.
power supply... From +-/38V regulated with 337/317 and TIP35/36 to +-/28V
Sound is so so...It is to sweet sounding. Bas is good midrange iz sweet but to soft and treeble is ...to plastic. Every kind of music has the same tipe of sound...no nevtrality. source pc-jriver-SUBBU DAC
I know that a lot of you have done this amplifier and I will kindly ask If anybody have any MODIFICATION RECOMENDATION.
I think to build in TUBE BUFFER with 12au7 or ecc88 or max gain of 2-4 and lower gain at lm3886 to 10-15. Have anybody experimented with lower values of resistors insted 22k-1k....2k-100R or with sound of gain 30 Vs gain 10. My friend have made some listening tests and say that with lower gain sound is better and less noisier, but is problem that with low output source gain could be to low.
What about volume poti. Is it better to have it in front of tube preamp or behind buffer preamp. I would like to have it after buffer, because at lower pot position you also get less noise. If poti is in fornt of tube preamp al noise get directly to amp. I have read that distorsion is higher with poti at the end of a tube preamp???
Her are some schematcs from AMPLIFIER and tube preamp-buffer suggestion.
You are welcome with ideas. Thank you.
Attachments
If you are going to add a tube, with obvious intention to color the sound, then why on earth a cathode follower circuit?
Sounds like contradiction to me.
Sounds like contradiction to me.
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Buffering of a high impedance input seems like a waste of resources.
If the Source cannot drive the cables and load, then buffer the Source, not the load.
If the Source cannot drive the cables and load, then buffer the Source, not the load.
Depends on the goal. Most builders of "buffers" don't really know what a buffer is, but they want to have some sort of distortion generator in-circuit. 12AU7 with low plate voltage will certainly fill that bill.
Even then, the distortion will not be low. Audibly high? Who knows, but there may be a certain psychological satisfaction in seeing a tube in there which causes the user's brain to "hear" a "tube sound."
i have seen a 6N2/12ax7 used as a buffer running on +-12 volt rails.....
surely colors the sound, the amp from china has many followings...
a quasi complimentary power amp stage, the amps sold in the hundreds....
for a price of about U$40....
surely colors the sound, the amp from china has many followings...
a quasi complimentary power amp stage, the amps sold in the hundreds....
for a price of about U$40....
Ok... I see.
Tubes are not appropriate solution.
Let*s go further.
Your opinion ...unregulated vs regulated LM3886?
Gain 10 VS 30 in comparison. Noise, thd, sound?
What do you suggest. Preamp with AD797 or LME49990 or LME49710ha into class A with gain 2-4 and followed by LM3886 at gain 10-15.
At TIP35/36C base position ...resistor 12R vs 2,2R... a little low current settings for filtering?
A class solution with bd140...how does it influence on sound.
I tried A class biasing with various opamps from resistor to fet and as a result, sound was always fuller, with more dynamic and speed.
I don*t need colorated sound. I think that colorated sound is now. Not enough difference between very good and bad recordings. Everything is average. I don*t like that.
Tubes are not appropriate solution.
Let*s go further.
Your opinion ...unregulated vs regulated LM3886?
Gain 10 VS 30 in comparison. Noise, thd, sound?
What do you suggest. Preamp with AD797 or LME49990 or LME49710ha into class A with gain 2-4 and followed by LM3886 at gain 10-15.
At TIP35/36C base position ...resistor 12R vs 2,2R... a little low current settings for filtering?
A class solution with bd140...how does it influence on sound.
I tried A class biasing with various opamps from resistor to fet and as a result, sound was always fuller, with more dynamic and speed.
I don*t need colorated sound. I think that colorated sound is now. Not enough difference between very good and bad recordings. Everything is average. I don*t like that.
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I agree, a tube is not the best idea at this point, you can't "cover up a bad smell with perfume" so instead of adding a pre-amp you either modify the amplifier you have (I'm not familiar with it - don't know if the layout is poor or if better parts and power supply will help), or you need a different amplifier.
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