Hi
I do not have the models for 5534 nor 31-32 but I read a few posts of the people who built the amp and they warned for the oscillations.
I did not build the circuit from the post 38
but you may expect very good sound from every transconductance amp!
After removing the 68R at the output, is there a problem with the Lm 1875 if you powered it up without a speaker load ?
Indeed, this is a fantastic amp !
Indeed, this is a fantastic amp !
Simple V-I Amp
Sorry kp93300 as I was away from the forums.
Try the circuit below, It is tested by me and is the simple version of what I had originally built. A non-polar 47uF cap replaces the DC Servo to make things simple.
1. Adjust 4R15 per your personal taste.
2. 4R9 controls the gain of the circuit
3. 4C5 controls the bass response with 4R6 and needs to be bi-polar.
All the best!
Sorry kp93300 as I was away from the forums.
Try the circuit below, It is tested by me and is the simple version of what I had originally built. A non-polar 47uF cap replaces the DC Servo to make things simple.
1. Adjust 4R15 per your personal taste.
2. 4R9 controls the gain of the circuit
3. 4C5 controls the bass response with 4R6 and needs to be bi-polar.
All the best!
Attachments
bimbla,
thanks for the circuit
What is the sound effect of changing 4R15? What is the usable range ? 100 R to 200 R ?
kp
thanks for the circuit
What is the sound effect of changing 4R15? What is the usable range ? 100 R to 200 R ?
kp
kp,
I acknowledge that I was inspired by Esa and padamiecki to jump into current amplifiers. I also acknowledge that the topology of the above circuit is from Introduction: Greetings and introduction and is not my original work. Do visit the website and enjoy a big sea full of wonderful information which is present there.
So with the credits taken care of, the 4R15 can be looked upon as a control that let's you change from voltage amplifier to a current amplifier. The value can be anything from 0E (short) to 1K. 0E makes it a 'pure' current amplifier.
Give LM1876 a try. It has better protection and has Mute and Stand-by pins to take care of turn-on/off noises.
As for booming/ extra bass, try sealed enclosures using the thiele small parameters of your driver. Make sure that the dimensions of the box follow the 1.6 rule to not make a square box. For tighter response, line the alternate walls of the enclosure with glasswool (not mineral wool or foam).
I have used Bose Acoustimass 3 with this amplifier and the results were simply out of the world, at par or even better than Genelec!
I would like to give MarkAudio drivers a try soon and would look to you for your findings.
I acknowledge that I was inspired by Esa and padamiecki to jump into current amplifiers. I also acknowledge that the topology of the above circuit is from Introduction: Greetings and introduction and is not my original work. Do visit the website and enjoy a big sea full of wonderful information which is present there.
So with the credits taken care of, the 4R15 can be looked upon as a control that let's you change from voltage amplifier to a current amplifier. The value can be anything from 0E (short) to 1K. 0E makes it a 'pure' current amplifier.
Give LM1876 a try. It has better protection and has Mute and Stand-by pins to take care of turn-on/off noises.
As for booming/ extra bass, try sealed enclosures using the thiele small parameters of your driver. Make sure that the dimensions of the box follow the 1.6 rule to not make a square box. For tighter response, line the alternate walls of the enclosure with glasswool (not mineral wool or foam).
I have used Bose Acoustimass 3 with this amplifier and the results were simply out of the world, at par or even better than Genelec!
I would like to give MarkAudio drivers a try soon and would look to you for your findings.
Hi guys!
I got too excited and ended up in a mess. It's your fault that my speaker is now having a multiple personality disorder (or maybe just showed its real self, dunno). 😀
I used the TDA2030 puny opamp and built the thing with parts right from junkbox and now vocals are throwing bolts at me!!! I mean, I am shocked. My cheap-a$$ fullranges seem like having a full-body mutation. I'm not sure whether I like or hate the sound but clearly it's wayyyyyy different from that with my other amps! Naturally my drivers are not built for current drive and probably have poor efficiency, but the vocals... the vocals seem wow! That said, there are obvious peaks and dips here and there. Looks like an 8 or 10 band eq is on its way.
Anyways, I think I will give the two channels a good long listen for the next few days, need to get over the confusion.
And thanks everyone here, I love surprises. ^^
shaan
I got too excited and ended up in a mess. It's your fault that my speaker is now having a multiple personality disorder (or maybe just showed its real self, dunno). 😀
I used the TDA2030 puny opamp and built the thing with parts right from junkbox and now vocals are throwing bolts at me!!! I mean, I am shocked. My cheap-a$$ fullranges seem like having a full-body mutation. I'm not sure whether I like or hate the sound but clearly it's wayyyyyy different from that with my other amps! Naturally my drivers are not built for current drive and probably have poor efficiency, but the vocals... the vocals seem wow! That said, there are obvious peaks and dips here and there. Looks like an 8 or 10 band eq is on its way.
Anyways, I think I will give the two channels a good long listen for the next few days, need to get over the confusion.
And thanks everyone here, I love surprises. ^^
shaan
Attachments
Last edited:
bimbla,
My markaudio 12p in superpensil matches very very well with this amp !. I sealed the bottom hole with 2 ordinary foams and change the input caps to 0.7 uf.
Most of my friends like it very much and offer to buy it off me !!
After building the tda 1541 dac , i will build Joes and your current amp for more fun !
regards
kp93300
My markaudio 12p in superpensil matches very very well with this amp !. I sealed the bottom hole with 2 ordinary foams and change the input caps to 0.7 uf.
Most of my friends like it very much and offer to buy it off me !!
After building the tda 1541 dac , i will build Joes and your current amp for more fun !
regards
kp93300
shaan,
I think a sealed fullranger design is ideal for this this type of amp .
Any ideas ?
I agreed it sound very very different from DOZ , F5, P3 , VSSA, aleph and TPA 3116 amps.
The best thing is that it is so simple and minimal demands on heatsink requirements .
regards
kp93300
I think a sealed fullranger design is ideal for this this type of amp .
Any ideas ?
I agreed it sound very very different from DOZ , F5, P3 , VSSA, aleph and TPA 3116 amps.
The best thing is that it is so simple and minimal demands on heatsink requirements .
regards
kp93300
I would describe the sound like detailed rich silk highs, accurate clear mids and punchy, deep, weak controlled bass. No chance for listening fatigue.
With qood quality equalizer at the input it will sound more flat in bass region, however I used to use my transconductace 1875 amp without eq with sealed Saba Acoustic Monitor 80 speakers with excellent impressions with extended bass (compared to conventional amps).
Interesting thread....
I use a First Watt F1J with a pair of Ref3a Episode speakers.... This was my foray into current drive... it's very, very good, no going back to voltage drive for sure....
I am also starting a speaker project, Bastanis Wildhorn... this should be even better than my current speakers. Hah... Current Speakers.... did yah see what I done there!!!
sorry... weird humour..
regards
J
I use a First Watt F1J with a pair of Ref3a Episode speakers.... This was my foray into current drive... it's very, very good, no going back to voltage drive for sure....
I am also starting a speaker project, Bastanis Wildhorn... this should be even better than my current speakers. Hah... Current Speakers.... did yah see what I done there!!!
sorry... weird humour..
regards
J
You may also ask Joe in his excellent thread about the speakers and crossovers: http://www.diyaudio.com/forums/chip...ductance-current-amplifier-3.html#post3580082
The Bastani Wildhorn will be a good one as it's a single 12" wideband driver, no crossover for needed for it. The tweeter uses a single capacitor. There is also a resistor which may or may not be needed which is placed across the main driver.
I have looked many times at Joe's thread too... very interesting..
Thanks
John
I have looked many times at Joe's thread too... very interesting..
Thanks
John
Hi,
In post # 46, is it enough to build the circuit as it is? or should there be a decoupling caps on board for the LM 1875s. Alternatively, if the power supply section is built on the same board, can we completely eliminate the decoupling caps?
In post # 46, is it enough to build the circuit as it is? or should there be a decoupling caps on board for the LM 1875s. Alternatively, if the power supply section is built on the same board, can we completely eliminate the decoupling caps?
trying to integrate the amps with my 2.1 x-over. the filter will have dedicated in/out sockets. the high pass out will be connected to the chipamp via a dpdt switch. offset at the speaker terminals is -1.8V when floating, and -80mV when speakers are connected.
Attachments
@shaan
Noticing how none of your wires are twisted, is it hum-free? My previous experiences dictate that i should go crazy in wire-twisting. That or use shielded wires.
Noticing how none of your wires are twisted, is it hum-free? My previous experiences dictate that i should go crazy in wire-twisting. That or use shielded wires.
hi ballpencil
it sounds hum-free (not Totally though, just a little mmmmmm in ear-over speaker mode).
The inputs will use shielded wires, of course!
it sounds hum-free (not Totally though, just a little mmmmmm in ear-over speaker mode).
The inputs will use shielded wires, of course!
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