[Nisbeth]

Thanks for the comments everyone. I've done a bit of tweaking to the layout, including adding pads for the pot as steinchen suggested. Other changes include widening the power and output traces from 50 to 70 mils and fiddling a bit with the silkscreen

Layout picture:

New Eagle files here


/U.

 

[tangent]

Quote:

Originally Posted by Jazper So like a ppa..

...with an inferior buffer, yes.

The LISA relies on hand parts matching to even approach the accuracy and adjustability of the PPAv2 buffer. Plan to have lots of JFETs on hand.

 

[ppl]

Its been along time coming and without any help from any one the LISA III is Born. This is soon to be available as PC Boards as soon as i get some one to distribute them. this amp is the natural evolution of my previous three channel Portable Amplifier. Note the full ground plane both top and bottom for a noticeable blacker background. Unlike its predecessors the LISA III has only one configuration and one choice of Op-Amp.
The LISA III therefore is more appealing to DIY'ers that want the best sound in an optimized complete system.

the first board run has arrived
http://www.esnips.com/doc/3ce63c1b-b...I-PCB-Top-Side

http://www.esnips.com/doc/bcd197d0-0...m-Side%3Cbr%3E

BTW i will have a couple of prototypes done before the International meet any one want to be the one to introduce my latest DIY Portable Amp?

 

[NelsonVandal]

Good news, this might be the best portable ever! Will it be possible to bypass the opamps, just using the buffers without too much offset? I almost never need more than unity gain.

 

[joze7205]

I really wan't an amp like this. Is it hard to build? For a n00b like me? (I've built my Cmoy and is about to build my first Pimeta.)

 

[Yen]

Quote:

Originally Posted by joze7205 /img/forum/go_quote.gif I really wan't an amp like this. Is it hard to build? For a n00b like me? (I've built my Cmoy and is about to build my first Pimeta.)

There is soon to be released the newest LISA III. It is actually released, but the PCBs or kits isnt ready yet for public. Just wait a bit, and read from this headwize thread and stay informed.

With a kit, or even a PCB and source parts locally, it is pretty easy and straightforward to build. I would say if you can build a PIMETA, then a LISA isnt much a problem.

 

[ppl]

Two LISA III's were shown at the International meet. boards should be available in about 3 weeks. The Schematics and parts list as well as the PCB have been changed slightly and new data will be posted when that is finished

 

[Yen]

It is great to hear that, ppl! I have been waiting for this to materialize.

 

[TzeYang]

was bored because my PN4392s have yet to arrive. So to not waste time, i built the L.I.S.A II.





Currently equipped with 2x 1000uF Panasonic FM, opamp power supply decoupled with 0.1uF metal films, TLE2426 rail splitter buffered by an OPA551 instead of the stock LM6171. OPA2107 configured in Unity Gain mode. Output transistors used are the BD138 and BD137 instead of the default BD139 and BD140. This amp runs off 2x 9V rechargeables.

How does it compare to the open loop Sijosae diamond buffers and Millett Diamond buffers i've built? It sounds nice, but heck it's a little too bassy for me and it is slightly inferior than the open loop buffers i previously built. I blame it on the output transistors used. I should have used the MJE2x3 pairs instead LOL. But since i was trying to cut down cost i used the BD13x pairs instead.

Actually, i was hoping someone could confirm whether the bassy signature is caused by the output transistors?

 

[NelsonVandal]

Nice work TzeYang. Isn't the bassy sound coming from OPA2107? I find it's bass accentuated just like OPA2132/34. I find the sound "nice" in a way with warm and open mids, but the treble is very unclear or muddy compared to the open loop buffers.

And hey! have you finished the Millet hybrid buffers? How do they sound compared to Sijosae's?

Did you ever compare the BD13x transistors to BC327/37 or the MJE's? I'm about to order 100 pieces and haven't decided wich trannies to use in the output position. I really love the sound of the BC327/37. The only thing I could wish for is a bit more slam to the sound, not just the bass.

I haven't had the energy to order the components, but I plan to build a semi-balanced open-buffer amp with common input and balanced output to see if it will sound even better. I've also ordered some SMD-boards and have plans for a "speed demon PINT" with AD8099/9631 (or AD8045).

 

[TzeYang]

Quote:

Originally Posted by NelsonVandal /img/forum/go_quote.gif Nice work TzeYang. Isn't the bassy sound coming from OPA2107? I find it's bass accentuated just like OPA2132/34. I find the sound "nice" in a way with warm and open mids, but the treble is very unclear or muddy compared to the open loop buffers. And hey! have you finished the Millet hybrid buffers? How do they sound compared to Sijosae's? Did you ever compare the BD13x transistors to BC327/37 or the MJE's? I'm about to order 100 pieces and haven't decided wich trannies to use in the output position. I really love the sound of the BC327/37. The only thing I could wish for is a bit more slam to the sound, not just the bass. I haven't had the energy to order the components, but I plan to build a semi-balanced open-buffer amp with common input and balanced output to see if it will sound even better. I've also ordered some SMD-boards and have plans for a "speed demon PINT" with AD8099/9631 (or AD8045).

after spending half an hour listening to the L.I.S.A. II, i can confirm that i REALLY don't like the close looped configuration with opamps. The treble, the neutrality, the transparency and the cleanliness are nothing as compared to the open loop buffers i've built. It sounds too bassy for my liking. Even the KSC 75 suddenly looses it's treble.

About the Millett Hybrid Diamond buffers, yes i finished building them, i just did not have enough time to update my signature LOL. They are using BC327/BC337 transistors for the input stage and current mirror stage, while the output transistors are BD137/BD138 pairs.

Sound quality wise, they beat every single amps i've built so far except the discreet PPA v2, which i think sounds better. The discreet PPA v2 is using MJE2x3 transistors for the output, so i guess the MJE2x3 pairs suits my ears better. I tried comparing the MJE2x3s to the BC3x7s and i found the MJE2x3s to be significantly better at everything. I would suggest going with the MJE2x3s not only because they sound better, but they are also tougher pairs of transistors and don't break that easily as compared to the BC3x7s and BD13xs.

In addition, the only thing i find great about the LISA II is the design. No transistor or components matching are required. Offsets are well below 1.0mV. Transistors are biased in Class AB.

Before i forget, since you're going to order 100+ of output transistors why not stack the output transistors? You get better current output capability. It's not a problem for us perfboard users

 

[ppl]

please note that the LISA iii is completely different than the LISA II. First and foremost difference is the LISA iii unlike the LISA ii is built upon the Three channel Amplifier Platform First introduced in the PPA The output stage on LISA iii employs my Latest Dyn-O-Bias III (The Non Switching output stage) utilized around a true Diamond buffer Biased with Jfet type CRD Diodes. LISA iii includes my Jfet Op-Amp supply rail isolation and low battery Indicator LED topology's used in my previous Amplifier designs. LISA iii also includes the AD744 operated with its internal output stage bypassed as is done on some of my previous designs also. LISAiii introduces the synergistic combination of using the AD-829 in the Ground channel as opposed to the AD744 as would be done if using conventional methods, moreover Lisa also debut my Full metal jacket PC board design using RF layout practices to lower the noise floor as well as improve the High frequency performance of the Amplifier.

So while the casual observer may think LISA III is simply an extension of the previous LISA's a look hear will bring you up to the most current published data and that still needs to be updated http://www.esnips.com/web/lisa-iii

 

[TzeYang]

ppl, thanks alot for the effort and contribution to the DIY community.

i have always been a fan of your amps. For instance, the PPA v2 and the PPA v2 with dyn-o-bias II.

I initially wanted to build the LISA III first, but because i don't have the parts to build one, i had to try the LISA II just for fun. One thing for sure, design wise, the LISA III is a total different beast than the LISA II.

Also, as for the AD744JN, is it necessary to use an external compensation cap even if the amp is configured at unity gain, and using compensation pin as output?

 

[ppl]

the most current Schematic and spec pdf for the LISA III http://esnips.com/doc/2927d82c-402d-...SPECIFICATIONS

This includes all the changes from the prototype and is mostly part number and value changes to reflect the best sounding out of the Built Prototypes.

Added parts consist of Jfet Op=Amp rail current sources replacing the previous resistors and replaced the to-92 Battery charger Regulator with a SMT D2 Pk (the TO-220 SMT Pkg.) version so as to charge the AA battery Pack used in the Expiation version and since just one resistor across the charger Regulator determinisms the charging current both the Standard version and the expedition version can be made with one PC Board Artwork. The previous battery Holders are replaced with Board mounted Clips so as to NOW FIT in the 1455J1602 case. In addition the Input RCA Jacks are Board mounted now so the Complete amp including batteries all are upon one board.

Heck with the Full metal jacket PC Board and all components are mounted upon it why use a case

Just kidding anyway see the PC Board http://esnips.com/doc/e20fc634-bc0c-...III-PCB-V-1.0B


Why did my image link dissipeer the nice Photo of the wood case Lisa that was hear now gone humm Why would that happen Oh and i can not relink it or even post the url on this post so ill post

 

[TzeYang]

Holy thanks!

is it me or does the LISA III looks much much much more easier to build than the previous LISA III? (due to the parts used)

Oh thank you very much ppl, the schematics is much clearer than the previous now.