[SamA]

If I hadn't already built the original Bugle and power supply, I'd be in on the Bugle2 in a flash.

Curious, though. If the new Bugle2 has "more modern and linear audio opamps," I wonder if the new opamps couldn't be dropped into the original Bugle. If so, what are they?

Good luck with the Bugle2, Jim.

[hagtech]

LM4562.

jh

[SamA]

The LM4562 opamps took my Bugle to a whole new level. I'm very pleased. More bass with oomph and and more detail. I've been running around like a kid sampling LPs!

[Folsom]

What about TI's  LME49720HA ? They are cheap only about $8 through Mouser.

[doug s.]

what about the audio-gd discrete op-amps?  they are listed as a replacement for the lm4562...

http://www.audio-gd.com/Pro/diy/OPA/OPAEN.htm

thanks,

doug s.

[hagtech]

The TI parts looks like it should work fine.  The OPA won't fit under the hood.

jh

[poseidonsvoice]

what about the audio-gd discrete op-amps?  they are listed as a replacement for the lm4562...

http://www.audio-gd.com/Pro/diy/OPA/OPAEN.htm

thanks,

doug s.

Great link. You can always rebox the Bugle 2 with your own enclosure, although, at that point you leave the 'budget' arena.

Best,
Anand.

[doug s.]

The TI parts looks like it should work fine.  The OPA won't fit under the hood.

jh

doesn't it depend on the size of "the hood"?  my bugle is in a big box: 





and, w/these extension leads, i don't think it would be an issue, anyway:



are there any other constraints?  would there be any of the op-amps that would be preferred to replace?  or not needed?

thanks,

doug s.

[Speedskater]

The last photo looks like an oscillator looking for a place to happen.  I hope that you have a high frequency O-scope.

[hagtech]

Hey, I was just going to say the same thing!  Don't ever think of using those extender wires.  You have to be absolutely clueless to try something like that...

jh

[doug s.]

Hey, I was just going to say the same thing!  Don't ever think of using those extender wires.  You have to be absolutely clueless to try something like that...

jh

hey!  i resemble that remark!   

the mfr sells these, specifically to be used in situations where clearance is an issue, and offers one w/a cap that is supposed to keep the op-amps working properly when the leads are >100mm.  so - as i am clueless, clue me in as to why i shouldn't use these, and what type of oscillation might occur and why.

also, as it's clear i don't need the extenders in my application, i'd still like to know  - are there any other constraints to using discrete op-amps such as these in the bugle?  would there be any of the op-amps that would be preferred to replace?  or not needed?

thanks for your help,

doug s.

[hagtech]

Sorry, I should not have been so rude.  But the power supply "loop" is not the only critical one.  The most sensitive spot is the negative input pin.  Any capacitance kills your slew rate and the opamp goes open loop (overshooting).  Inductance in the feedback network adds phase shift and creates an oscillator, typically in the MHz region.  And like speedskater said, you most likely won't see it without proper test equipment.  Got that "20MHz" filter set on your scope?  Poof, it's not there!  An opamp with a parasitic RF oscillation will burn extra power and often cause a shift in dc bias.  This can manifest itself sonically in a number of ways.  Lack of dynamics, huge even order distortions, shrillness, clipping, and open loop operation. 

On the other hand, if properly implemented, you should be able to use many different opamps in the Bugle2 circuit.  Including discrete ones.  You need low noise in the first stage, low offset voltage in all stages, and solid output drive in the final stage. 

jh

[doug s.]

Sorry, I should not have been so rude.  But the power supply "loop" is not the only critical one.  The most sensitive spot is the negative input pin.  Any capacitance kills your slew rate and the opamp goes open loop (overshooting).  Inductance in the feedback network adds phase shift and creates an oscillator, typically in the MHz region.  And like speedskater said, you most likely won't see it without proper test equipment.  Got that "20MHz" filter set on your scope?  Poof, it's not there!  An opamp with a parasitic RF oscillation will burn extra power and often cause a shift in dc bias.  This can manifest itself sonically in a number of ways.  Lack of dynamics, huge even order distortions, shrillness, clipping, and open loop operation. 

On the other hand, if properly implemented, you should be able to use many different opamps in the Bugle2 circuit.  Including discrete ones.  You need low noise in the first stage, low offset voltage in all stages, and solid output drive in the final stage. 

jh

thanks for the more detailed reply!     perhaps this is why audio-gd runs an extra wire, (which looks like it goes from the negative input pin), and recommends you ground it separately:

The discrete opamp not only can replace typical single or double output opamp, but it also has a separate earth(ground) wire which can be connected to the earth of the player. Even if the earth wire is not connected or used, the output sound will have slight difference. The user can choose to decide on his own, but we recommend to connect the earth wire to ground.  Please do not  connect OPAs earth wire to AC power socket ground.


thanks again,

doug s.

[Speedskater]

"doug" I don't think that the designer (I hesitate to call him and engineer) realizes what he is getting the circuit user's into.

[doug s.]

"doug" I don't think that the designer (I hesitate to call him and engineer) realizes what he is getting the circuit user's into.

s/s, i am simply a nowice, wanting to learn a bit as i possibly upgrade my system.  however, i do know that audio-gd products have received uniwersal praise; so i am sure the engineer (i have no hesitation whatsoever to call him that) has an idea about what he's getting the circuit users into.  the first iteration audio-gd op-amp, which is still sold, as the "sun", was distributed by burson as their own, at a considerable mark-up.  (do you also believe burson are not engineers?) 

there is no doubt that, when retailing something like a discrete op-amp chip, the designer cannot know all the possible circuits where they may be used.  prewiously, in inquiring about using this op-amp in a particular tuna, i was told that its woltage requirements could not be supported by the particular tuna in question.  so, i am aware that there may be limitations for something like this; i am sure its designer is also aware of this.

if you have any constructive info about the use of audio-gd's grounding wire, i'd love to hear about it.

doug s.

[Speedskater]

It not about the ground wire,  it's about suggesting to a person that does not totaling understand the circuit, to just hook-up a wire.  "Ground" is not what most people think it is!  What appears to you to be the ground point may not be a ground point to the op-amp.

This is a 30 year old article by Henry W. Ott

"Ground- A Path For Current Flow"
http://www.hottconsultants.com/pdf_files/ground.pdf

not familiar with burson.

Note: I found "Burson Audio Buffer" at 6moons and Positive Feedback.

[Brinkman]

The LM4562 opamps took my Bugle to a whole new level. I'm very pleased. More bass with oomph and and more detail. I've been running around like a kid sampling LPs!

How does it compare to other opamps you've rolled into it?

[xtreme4099]

On my Bugle1B,  I used the LM4562 and Metal TO-99 LM4562 and I still liked the LM49990 better than both, it had a blacker lowered noise floor background, sounded snappier, and a bit more detailed, liquid and natural; the LM4562 sounded etched by comparison.  This was several A/B's back and forth on a few of  the same tracks. Thing sounds great on the Modded Rega P3 by the way

LME49990 specs here :
http://www.ti.com/product/lme49990

You can get them already assembled here : http://cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx

When the Bugle2 gets here, planning to go all out with z-foil vishay tx2575 resistors, flims caps and aluminum organic semi caps like maybe oscons if possible.

On listening tests, the organic aluminum's were a step up from even blackgates F/FK on my headphone amp, they were less colored, neutral, had more snap, and detail.  I had a duplicate of my headamp to play with, one with BG"s and  the other with Oscons to AB back and forth.

[Folsom]

On my Bugle1B,  I used the LM4562 and Metal TO-99 LM4562 and I still liked the LM49990 better than both, it had a blacker lowered noise floor background, sounded snappier, and a bit more detailed, liquid and natural; the LM4562 sounded etched by comparison.  This was several A/B's back and forth on a few of  the same tracks. Thing sounds great on the Modded Rega P3 by the way

LME49990 specs here :
http://www.ti.com/product/lme49990

You can get them already assembled here : http://cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx

When the Bugle2 gets here, planning to go all out with z-foil vishay tx2575 resistors, flims caps and aluminum organic semi caps like maybe oscons if possible.

On listening tests, the organic aluminum's were a step up from even blackgates F/FK on my headphone amp, they were less colored, neutral, had more snap, and detail.  I had a duplicate of my headamp to play with, one with BG"s and  the other with Oscons to AB back and forth.

For the right resistance ranges you could go an even step above naked Vishay resistors.

[Napalm]

The discrete opamp not only can replace typical single or double output opamp, but it also has a separate earth(ground) wire which can be connected to the earth of the player. Even if the earth wire is not connected or used, the output sound will have slight difference. The user can choose to decide on his own, but we recommend to connect the earth wire to ground.  Please do not  connect OPAs earth wire to AC power socket ground.

The indications above plus the soldering style and skills as seen on their web page are telling me to stay away.