[ppl]

I as some of you might remember was investigating the Possibility of A class A Portable Amp at that time I was Thinking the EL-2009 at 63 Ma a farly good Class a range for most Headphones. However i run across a buffer that when stacked give 400 Ma of output Current (unprotected i might Add) and consume about 40 Ma per the Stack of 4 about 20 Ma Ea. Still good Class A. BUT the big suprise in in the Listening. Using the AD-8610 as an opamp this AMP Defines Clarity and refinement. I would Highly sugest this combo in a Multiloop comfiguation. I was flat Impressed and i as you Know listen to Great sounding Amps. This is as close to sonic Perfection as i have yet to hear out of any Audio Electronics. I am sure a Dual mono or Mono Block Version of this will perform as well or better as any solid state Headphone Amp Available. Oh Ya it Also Runs on batteries. Separate ones for each channel. Thanks tomo for the Toy car Battery Tip. see hear for the Buffer. http://www.intersil.com/design/param...?pn=HA3-5033-5 This is good.For Burr Brown Fans This http://focus.ti.com/docs/prod/produc...tNumber=OPA633 is the Same thing as theHarris Part.

 

[morsel]

The BB/TI OPA633 part blows away the old Harris/Intersil part, with greatly improved offset voltage and slew rate. Yowie, 21-25mA quiescent current.

Way too much for batteries, no? PPL, is this an open loop buffer, i.e. directly stackable? It does not have a BUFnnn designation.

 

[aos]

ppl, still nothing wrong with using EL2009 right? I got a couple of them waiting to be used for this purpose. They are much more powerful as well and don't need to be parallelled, right?

 

[ppl]

aos: the 2009 sounded Great with the 825 it tamed the Sibelence alot compared to the Lower powered 2008, I am going to reavaluate this with the 8610. So far the Ha-5033 OPA-633 and a stack of 4 EL2002's next followed by the 2008 and then the 2001.. I would think that what i am hearing with the Ha's is the high bias because the most stricking difference between this and like a 2001 is Clarity and quick and articulate sounding. in direct comparrison the 2001 and 2008 sound somewhat slower and less detail and ambience vs the 2002 and the 5033.

 

[aos]

OPA633 has pretty bad distortion figures. I know feedback can improve it but still...

 

[puppyslugg]

Hi ppl,

Where can you purchase the ad8610's?

 

[Possum]

You can order directly from Analog Devices here:

http://products.analog.com/products/...product=AD8610

 

[ppl]

High Distortion It looks like 0.05% or less at any reasonable Output. the EL-2001 and the likes we like so mutch but the Data sheet claims 1.0% THD for them....

EL-2009 & AD-8610= at aos's prompting i tried the EL-2009 in the same Amp circuit as some of my other Amps so as to Keep Most the same Except the Buffers. Like the lower bandwidth EL-2008 this 1 Amp Buffer Has about 120MHz. bandwidth @ 50 Ohms. vs the EL-2008's 90MHz. @ 50 Ohms. The Bias Current typicaly runs abou 13-15Ma for the 2008 to 50-70 for the 2009. Wen selecting 2008's for Battery Operated amps I use the ones with the Lowest Current Drain for the 2009 I select the Higest so as to Keep Class A longer. I selected a 65Ma pair and Heatsinked using the small slip-on TO-220 case. This Keept the 2009 cool whwre as with no Heatsink at +/- 10 volts would Thermaly tax the Buffer so Heat Sink is Required.

EL-2008 vs EL2009>>> The 2008 sounded alot slower and slightly darker than the wider bandwidth 2009. The 2009 shares with the 2008 the ability to Kick out the jams into Low Impedance Cans Like Sony's and Gradio's. Use Two pair of these at the same time No Problem Not evean a Breef dropout when the Other cans were Pluged in as this shorts the Output to ground untill the plug is Fully inserted. The most noticable Difference sonicly Between these two Buffers is the Clarity in the midrange and lower trebel is slightly more Refined in the EL-2009, than in the 2008. The sence of unrestraind Power throughout the Midrange and the Upper octave's Bells come across Magnifent on the 2009 where the 2008 seems to take the latter part of the Bells delay away into darkness, on the 2009 these same Bells gently ring without breakup well into the Mastertape His and other what seems to be Digital Grunge. In eather case Both of these Buffers work wonderfully with the AD-8610 Opamp. This is similar to the Differences Between theEL-2001 and EL-2002.

EL-2009 vs HA-5033/OPA633>>>> This i listened to for just a short while in direct Comparrison the EL-2009 had alot more Guts than this stack of 6 5033/633's Both have great sounstage and seem similar in this regard. The 5033/633 did have an Extended Trebel over the ELantec Buffer. Also i thought the 5033/633 had less Distortion Throughout the Audio. The Elantec Parts have Always sounded Cleener than Similar Buffers Like The BUF-634, But in comparrison to the 5033/633 The 2009 appears to have added upper harmonics in addition to the Main Note. This quality i did not notice untill i did this test. My main gripe about the 5033/OPA is the Total lack of Guts.I meaen Six 100 Ma Non current Limited Parts should Drive 60 Ohm Cans Just Fine, NO so I think More of these will be needed to Bring the Dynamic Punch Factor Up. The EL-2001, are evean Better let alone the 2008's and 2009's whitch Kick Dynamic But Better than any other Monolithic Buffer and only bettered by the now Disconued but Spendy when it was available Apex WB-05 Hybird in a TO-3 Case. But Cost $200.00 Each 10 years ago. so if ya got some 2008's and 2009's save them four your Killer Output stage. The 5033 and OPA-633 I think i would Love on chamber Music Because of it's Liquid seemless Midrange to lower treble, where most Solid State Amps of Any Tecnology Have Problems in in Comparrison with Good Tube Amps. So if Guts are what you want 2008 and 2009.. for extreamly low Preceived Distortion the 5033/opa are the finest in this regard than any Buffer i have heared Including the WB-05. But Who need Guts fore Chamber Music anyway.

I gess toy know your a fanatic when you have a Separate amp for Different Music.

 

[morsel]

Thanks for the great reviews PPL.

 

[aos]

Yes, thanks ppl! I can now use EL2009 with confidence. 1A buffer, yeah baby!

 

[Joe Bloggs]

Another Porta Corda coming to me in the mail, this time biased for Class A operation with 1.2kOhm resistors out of the factory. How does the LM6171 compare to the EL2009 for Class A operation?

 

[Possum]

You mean how does the LM6171 used as a buffer compare to the EL2009?

 

[aos]

EL2009 is buffer, meaning it has only one input and has fixed gain of 1. LM6171 is fully featured operational amplifier that can be configured to use as a buffer. EL2009 has nonstandard package which is completely different from standard DIL that majority of opamps come in. EL2009 can supply more far more current, by a factor of 10 at least. Comparing these two, while maybe not like comparing apples to oranges, is still very hard. These two chips are in different categories alltogether.

 

[Joe Bloggs]

Sorry

So what was the main opamp that ppl used in his portable amp? The AD 8610?

Really, I have no business posting here

Joe

 

[ppl]

Joe: Yes i am using the AD-8610 in at least two of my amps and will most lickly do all my Portables including the BUF-634 X 3, and deffinitly the EL-2008. this Amp draws only about 40 or so Ma. so is battery frendly for 16 AAA's. And the 8610 hav a bonus in Portables as being low Current Consumption, Heck 60 Volts Per uSec and a 24 MHZ. bandwidth on 2.8 Ma of supply Current. It sounds Good at lower Voltages, Evean a single 9 Volt battery will Power this Opamp Well But Low sensitivity cans may need more swing as from a pair of 9 volts.

I am still inclined to use the AD-825 in one Portable since I am Liking the speed of it and a stack of 6 EL-2002's 180 MHz. Buffer. The AD-8610 also sounds Wonderfull with the 2002.