Good results with LME49720
Today arrived two LME49720 from USA. Considering the actual transaction cost for the item, I believe I made a very good deal at 20USD post included.
At home, after some planning..heating the iron and focusing on the matter, I replaced the LM4562 by the new metal can opamp.
I could not sit it on the pcb because of the circular leg pattern so I hope there is no microphony.
First impressions with the Mighty CD53....
Higher detail and speed on the bass;
Sweeter, more life like female voice;
Faster decay on mid frequencies;
Noticeably more open mid frequency;
Downsides are maybe a little less drama and power on the bass.
Switching to the TT, things got much better than before the mod:
Mid and high freq detail increased noticeably, bass got tighter, better stereo imaging and wider soundstage.
In this case I do not notice any lack in bass power, it just got faster and more detailed. (PS: I have been playing with VTA in the weekend and got rid of some stridency, gaining loads of bass. This mod just gave more control to this added bass).
I will be reporting evolutions after some run in period but it is a keeper
Ricardo
PS: Please excuse the BG Nx around the electronic switch... This was done when I was really noob.
Today arrived two LME49720 from USA. Considering the actual transaction cost for the item, I believe I made a very good deal at 20USD post included.
At home, after some planning..heating the iron and focusing on the matter, I replaced the LM4562 by the new metal can opamp.
I could not sit it on the pcb because of the circular leg pattern so I hope there is no microphony.
First impressions with the Mighty CD53....
Higher detail and speed on the bass;
Sweeter, more life like female voice;
Faster decay on mid frequencies;
Noticeably more open mid frequency;
Downsides are maybe a little less drama and power on the bass.
Switching to the TT, things got much better than before the mod:
Mid and high freq detail increased noticeably, bass got tighter, better stereo imaging and wider soundstage.
In this case I do not notice any lack in bass power, it just got faster and more detailed. (PS: I have been playing with VTA in the weekend and got rid of some stridency, gaining loads of bass. This mod just gave more control to this added bass).
I will be reporting evolutions after some run in period but it is a keeper
Ricardo
PS: Please excuse the BG Nx around the electronic switch... This was done when I was really noob.
Attachments
Aajor mod in sight !!!!!
After building with succes the magnific Salas Riaa with dedicated R6mod shunt, I believe I do not need the 101b internal Riaa circuit.
As some of you already know, I believe in "garbage in -> garbage out" theory so now I have two very high Q sources to feed into the 101b, the magedonTT with salasriaa and the über CDP.
Actually these two sources use the same line in (TAPE) of the preamp so everytime I want to change source, I need to reconnect the RCA´s. (This is good to keep them clean but not very user friendly)
So my idea is to replace the 101b internal head amp + riaa eq modules by a modded board based on a meridianMC module I bought in the net (Worst riaa amp module I ever heard) that I itend to use as a signal bypass wire.
I will remove all the components of the MC board , and use shunts between the in/out golden sockets.
This will enable me to use the CDP in the (TAPE) in and the new Riaa in the phono input.
My main issue is the salas riaa inpedance matching... what should be the minimum ohm value in the 101b input ?
Ricardo
After building with succes the magnific Salas Riaa with dedicated R6mod shunt, I believe I do not need the 101b internal Riaa circuit.
As some of you already know, I believe in "garbage in -> garbage out" theory so now I have two very high Q sources to feed into the 101b, the magedonTT with salasriaa and the über CDP.
Actually these two sources use the same line in (TAPE) of the preamp so everytime I want to change source, I need to reconnect the RCA´s. (This is good to keep them clean but not very user friendly)
So my idea is to replace the 101b internal head amp + riaa eq modules by a modded board based on a meridianMC module I bought in the net (Worst riaa amp module I ever heard) that I itend to use as a signal bypass wire.
I will remove all the components of the MC board , and use shunts between the in/out golden sockets.
This will enable me to use the CDP in the (TAPE) in and the new Riaa in the phono input.
My main issue is the salas riaa inpedance matching... what should be the minimum ohm value in the 101b input ?
Ricardo
Now looking at the output module, I have 1 opamp rigged as an inverting voltage amp.
The feedback resistor R1 is 100K.
The input resistor R2 is 6.9k.
GAIN= R1/ R2 = 14.49
In parallel with the feedback resistor I see a small cap (40~60pF ??) Not sure
This cap is intended to limit the bandwith of the pre and creates a rolloff acording to the formulae: C = 1 / (2 * pi * R * f)
Admiting the cap is 40pF, the rolloff appears at 39788Hz.
I do not know if I can lower this value without compromising stability or S/N.
Hope someone care to comment.
Ricardo
The feedback resistor R1 is 100K.
The input resistor R2 is 6.9k.
GAIN= R1/ R2 = 14.49
In parallel with the feedback resistor I see a small cap (40~60pF ??) Not sure
This cap is intended to limit the bandwith of the pre and creates a rolloff acording to the formulae: C = 1 / (2 * pi * R * f)
Admiting the cap is 40pF, the rolloff appears at 39788Hz.
I do not know if I can lower this value without compromising stability or S/N.
Hope someone care to comment.
Ricardo
BIG IMPROVEMENT
(I am getting good at this )
Just replaced the +-15V regulators in the 101b by the equivalent Spower....Briliant devices (Thank you Brent !!!)
Detail is greatly enhanced and there is a lower noise floor.
I really apreciate the bigger sounstage (due to low level detail enhancement).
Ricardo
PS:
The feedback bypass cap is used to lower the noise and limit the preamp bandwith.... I will not touch it until I decide to go discrete opamp.
(I am getting good at this )Just replaced the +-15V regulators in the 101b by the equivalent Spower....Briliant devices (Thank you Brent !!!)
Detail is greatly enhanced and there is a lower noise floor.
I really apreciate the bigger sounstage (due to low level detail enhancement).
Ricardo
PS:
The feedback bypass cap is used to lower the noise and limit the preamp bandwith.... I will not touch it until I decide to go discrete opamp.
103 Power Amp recap
Just needed to report my last mod:
After heavily modding the 101 pre, I needed to do something to the 103 power amp.
After long term considerations I decided to keep the original 100uF cap values and used 100uF 35v Ruby ZA.
Wonderfull mod.... Outstanding results regarding detail and stage size.
Also big improvements in dynamics.
A must do mod.
Ricardo
Just needed to report my last mod:
After heavily modding the 101 pre, I needed to do something to the 103 power amp.
After long term considerations I decided to keep the original 100uF cap values and used 100uF 35v Ruby ZA.
Wonderfull mod.... Outstanding results regarding detail and stage size.
Also big improvements in dynamics.
A must do mod.
Ricardo
I am now replacing the 101 preamp by a home made pre that does not invert signals.
As the 101 preamp uses an opamp with inverting topologie, should I presume the 103 power amp is also an inverting amp ?
Hope someone can remenber these units and help me in this case.
Here is the schematic of the power amp:
Attachments
I no longer use the preamp but I remember mine is a opamp preamp (not discrete).
I did replace that opamp by a LME49720 and also replaced the 15v regulators by my discrete version.
In the PSU I replaced the caps.
In the power amp, I replaced all EL caps by equivalent valued BGN.
Recently I built a new PSU with two big TX and it sounds very well indeed.
I did replace that opamp by a LME49720 and also replaced the 15v regulators by my discrete version.
In the PSU I replaced the caps.
In the power amp, I replaced all EL caps by equivalent valued BGN.
Recently I built a new PSU with two big TX and it sounds very well indeed.
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