M-audio opamps replacement

[jasonhanjk 0]

What speaker did you have? My HD600 win my Altec Lansing ACS56...

[ablaze 0]

depends on what cans you're using. for me I'm using very low-impedance, high efficiency cans, so it sounds pretty good even without any amp. BUT I got a headphone amp ordered already. what cans are you using?

[julery 0]

What speaker did you have? My HD600 win my Altec Lansing ACS56...

I using Aego2 leh. I guess my newly bought Philips HP890 loses to Aego2.

 

Or izzit need to burn-in for 3 days first? Or the stock cable sucks?

 

[julery 0]

depends on what cans you're using. for me I'm using very low-impedance, high efficiency cans, so it sounds pretty good even without any amp. BUT I got a headphone amp ordered already. what cans are you using?

Using Philips HP890 lor, dun have the OMG factor.

 

Dunno much about impedance stuffs but it stated on box:

 

Impedance : 32 Ohm

 

Frequency range : 5-30,000 hz

 

 

[ablaze 0]

how much was the Aego2? the Philips's only $70..not a fair comparison right. get equivalently priced headphones to compare

[julery 0]

how much was the Aego2? the Philips's only $70..not a fair comparison right. get equivalently priced headphones to compare

I got it at $250 for the Aego2.

 

As I mentioned in my other thread, it work smoothly and with punch just by plugging it into my Sony FM stereo walkman.

 

Oh yes, the Sony FM stereo Walkman with H-890 plug into it can match the Aego2 anytime.

 

What is missing?

 

mod edit: I've replied to you in your HP890 thread. perhaps you'd want to start a new thread, so as not to go too OT on current threads

Edited July 21, 2003 by ablaze

[ablaze 0]

thanks to you getting me interested in the AEgo2, now I got a pair too

 

anyway, back to the thread.

some czech guy the revo mod too. damn. his soldering looks much better than mine

[adhoc 0]

wow like that he might even be able to send it in for servicing if anything goes wrong. it looks exactly like a new revo at first glance!

[ablaze 0]

yeah. thats damn good soldering. I'm hoping he's got some smd soldering station or something. If he did that by hand too, then I'm very

[ablaze 0]

update:

Cliff Watson at AVSforums (one of the respected guys there) did the mod and apparently wasn't too impressed

http://www.avsforum.com/avs-vb/showthread....threadid=285366

Revo Mod Test Results

 

I know that I’m going to get flamed for this report, but I think it’s best to get the truth out in the public. I am amazed at how easy some people can be lead astray by glowing reports of major improvements without the least amount of supporting data and test conditions used to draw that conclusion. The paradigm for DIYer’s seems to be “if it cost more then it absolutely must be betterâ€.

 

Replacing a “workhorse†integrated circuits with the latest and greatest (and expensive) ICs without redesigning the whole circuit including the resistors and capacitors to match the properties of the mother IC is foolish and in my opinion a waste of time (and money). Just because an IC is pin compatible does not mean that the rest of the circuit is optimized to the replacement IC.

 

I tested Revo unmodified and with a bypass jumper shorting the electrolytic blocking capacitors.

 

I tested and compared the Revo above with a modified Revo with 5532 Op Amps replaced with AD8620 (with and without electrolytic blocking caps) and with metal film bypass caps.

 

I’m not getting into a pissing contest by listing the names of the components in my audio system. I learned a long time ago that no matter what equipment you own some a-hole will find fault with it to claim invalid results. Let’s just say that my amps, speakers, speaker wires and interconnection cables cost more than the annual budget in a small third world country.

 

My stereo amp has two power supplies (one for each channel), power bandwidth (-3dB) of 5Hz to 130kHz, gain of 29dB with 2dB additional dynamic headroom, damping factor >1000, distortion < 0.005% and more wattage than anyone would ever use.

 

The 2.1 speaker system has a frequency response of 20Hz to 26kHz +1, -3dB and is very clean, clear and detailed. The speakers have clear, detailed highs without being overly bright. The powered subwoofer is a sealed design and has always been tight. It does not produce sub frequencies as loud as ported subs, but I prefer tighter bass for music.

 

Testing setup;

 

I used 2 computers, one with unmodified Revo and one with the various Revo mods. Winamp 2.91 with Kernel Streaming plugin was used for both and the Revo control panel had the identical settings. A remote was programmed to start playback on both computers from a single code.

 

Both Revo cards were connected to a remote control audio switch box with identical cables and the output from the box was feeding the amps. The same remote control was used to A/B the output.

 

My real time audio spectrum analyzer has a resolution of 1dB that I didn’t think was good enough for this test so I measured the voltage through out the signal path with a digital scope and audio sweep signal generator to within 1 mV.

 

All music used for testing was ripped to drive “C†as wave 16/44.1 for playback. CDs used are as follows:

 

Norah Jones – Come Away With Me (songs - One Flight Down & Turn Me On)

Joe Sample – Carmel (songs – More Beautiful Each Day & Midnight and Mist)

O Brother, Where Art Thou? (songs – Down To The River To Pray & I Am A Man Of Constant Sorrow)

Tchaikovsky – (songs – “1812†Overture & Serenade in C for Strings) (This is the Telarc Digital version of 1812 with real brass cannons)

Vivaldi – The Four Seasons – Concerti, Op. 8, Nos. 1-4 (all tracks)

Dixie Chicks – Wide Open Spaces (songs – Wide Open Spaces & I’ll Take Care Of You)

Erich Kunzel – Cincinnati Pops Orchestra (songs – The Hunt For Red October & Terminator Theme)

Diana Krall – Stepping Out (songs – Between The Devil And The Deep Blue Sea & Straighten Up And Fly Right)

 

Test result #1:

 

I modified the Revo by replacing all three opamps on the front L/R channels (1 used as low pass filter and 2 as buffers), the center/sub channel opamp, and bypass all blocking caps for the 3 channels. The other Revo was not modified in any way.

 

I’ll discuss the unmodified Revo at the end in my conclusion. With the replacement opamps (AD8620) and bypassed blocking caps the quality of the mid-high frequencies is particularly poor, where the mid-band is brittle and aggressive, and higher frequencies are edgy, cold and fatiguing to listen to. The mid and high bands got skinny and you can think of this as a baritone sounding like Tiny Tim.

 

Test Result #2:

 

This test was done with the bypass removed from the blocking caps.

 

This helped improve the mod greatly, however, there was still an ever so slight edginess to the high band with certain music such as loud solo piano and violins.

 

Test Result #3:

 

This test was done with a metal film cap used to bypass the blocking cap.

 

Forget this one because the high band took a dump and sounded like the low pass cutoff was around 4kHz.

 

Test Result #4:

 

This test was done with the new opamps and the standard DC blocking caps in place. Also the other Revo was modified to bypass the DC blocking caps.

 

Conclusion!!!

 

The Revo without DC blocking caps (with old 5532 opamps) sounded absolutely identical to the Revo with new (and expensive) opamps and caps in the circuit.

 

So if you have an entry-level sound system with rolloff of the high band you may benefit from the replacement of opamps. For people with mid to high-end sound systems you have two options depending on the sound you would like to have.

 

If you like the pleasant sound of tube amps the unmodified Revo is for you and if you prefer the sharp digital sound you can get it with a simple and inexpensive mod by soldering jumper wires across the DC blocking cap legs.

 

The low band (sub bass) was the same from my sealed sub reqardless of the modifications tested.

 

Flame suit on

[Wortel 0]

Where is the pic of your revo soldering ablaze?

[ablaze 0]

I did post some pics on page 5 of the thread wortel

eg.

[Wortel 0]

ok I'll read it.

Edited August 7, 2003 by Wortel

[adhoc 0]

please read through the entire thread.

[Rameish 0]

Ablaze,

 

your soldering skills have come a long way :-)