Boss - OD-1 Quad Opamp Comparison Video

[Groovenut]

Hey all. I recently acquired a 1982 OD-1 and decided to set off on a little research about the original. I was able to get the parts together to build one and decided to do some in production quad opamp comparisons with the out of production Raytheon RC3403. Here's the clip of the test. Youll need to decide for yourself about which one sounds best.

http://youtu.be/MjKFNFFfviY

[FiveseveN]

Nice to see a controlled comparison for a change.
Maybe it's too early in the morning but they sounded pretty much identical to me .

[Groovenut]

Sorry for the lack of detail in the post. It was late

The only part that wasn't completely controllable and repeatable was the reverb reaction to the input signal. As such, when I have done frequency level file comparisons the main difference between each file is the reverb. The reason for this is the reverb is being generated by the reamped signal chain. I wouldn't have used reverb at all, but this test was meant to be listened to rather than measured. As I have more time I will do frequency plot overlays of each of the test files to visually show the differences and I'll post those as well. It was an interesting test and as well, so were the findings.

[Duckman]

they sounded pretty much identical to me

+1
Any way, there's "something" I like with the 324

[Groovenut]

I ran and captured visual frequency comparisons between the RC3403 and the other chips. I did comparisons between the chords only half of the wav, the notes only half of the wav and the full wav file. So that's 15 files per gain setting. I can post links to the zip files of each gain setting group or the individual files. I don't wish to clutter things if folks would prefer to download to view. What would be preferred by those interested?

[Groovenut]

here's the zips
https://www.dropbox.com/s/p3i0f7ngn8x93 ... l%20D0.zip
https://www.dropbox.com/s/t6h662ilaes13 ... l%20DN.zip
https://www.dropbox.com/s/9feaikjqs49ui ... %20D10.zip

[Groovenut]

Full wav file comparison - Drive at 0
https://www.dropbox.com/s/cicr9ouvf4s1f ... 20full.jpg
https://www.dropbox.com/s/zl3siuxnvjgo5 ... 20full.jpg
https://www.dropbox.com/s/e4j80uucnombw ... 20full.jpg
https://www.dropbox.com/s/30mg2e6oiaa2b ... 20full.jpg
https://www.dropbox.com/s/mq9oafjltr5oa ... 20full.jpg

Chords only
https://www.dropbox.com/s/c43wt1frtdyof ... Chords.jpg
https://www.dropbox.com/s/wc5y2z5kp1q6h ... Chords.jpg
https://www.dropbox.com/s/qsna4nwykm4nv ... Chords.jpg
https://www.dropbox.com/s/h7qt44j4ujxw1 ... Chords.jpg
https://www.dropbox.com/s/1sl4b4hvu4xoi ... Chords.jpg

Notes only
https://www.dropbox.com/s/nyma30k2fu1gn ... 0Notes.jpg
https://www.dropbox.com/s/ptacjf8p5r7ar ... 0Notes.jpg
https://www.dropbox.com/s/q6k9b5be1v1c7 ... 0Notes.jpg
https://www.dropbox.com/s/mving6fkj4lsh ... 0Notes.jpg
https://www.dropbox.com/s/7w40ipl99e8zm ... 0Notes.jpg

[Groovenut]

Full wav file comparison - Drive at noon
https://www.dropbox.com/s/0lqcev69e9e1a ... 20full.jpg
https://www.dropbox.com/s/vg6r7hl6ni5ql ... 20full.jpg
https://www.dropbox.com/s/8yi152gcfz9sa ... 20full.jpg
https://www.dropbox.com/s/8fbcpzu94lvbg ... 20full.jpg
https://www.dropbox.com/s/7icn4sexqps46 ... 20full.jpg

Notes only
https://www.dropbox.com/s/a5zbcrr8e8i5x ... 0notes.jpg
https://www.dropbox.com/s/thtstpshrmn7y ... 0notes.jpg
https://www.dropbox.com/s/qhxjbziltegt8 ... 0notes.jpg
https://www.dropbox.com/s/wem0rvp4ntvy6 ... 0notes.jpg
https://www.dropbox.com/s/2u4qaleozjiej ... 0notes.jpg

chords only
https://www.dropbox.com/s/qla0c12x841nu ... chords.jpg
https://www.dropbox.com/s/w5s0gxnzojhze ... chords.jpg
https://www.dropbox.com/s/teonvdapmvrd3 ... chords.jpg
https://www.dropbox.com/s/mxlwqeksqwvnl ... chords.jpg
https://www.dropbox.com/s/jom1v7teepwnh ... chords.jpg

[Groovenut]

Full wav file comparison - Drive at 10
https://www.dropbox.com/s/cugunjiws82gc ... 20full.jpg
https://www.dropbox.com/s/8thd3bkmlcypg ... 20full.jpg
https://www.dropbox.com/s/ytu1f4daijti4 ... 20full.jpg
https://www.dropbox.com/s/7n2dfr0n502hz ... 20full.jpg
https://www.dropbox.com/s/9dk1vah52dreg ... 20full.jpg

Notes only
https://www.dropbox.com/s/9vccr6bpjvpuu ... 0notes.jpg
https://www.dropbox.com/s/m7am813l0sum8 ... 0notes.jpg
https://www.dropbox.com/s/pvsvso5bc34vy ... 0notes.jpg
https://www.dropbox.com/s/je6bpqzrin3u1 ... 0notes.jpg
https://www.dropbox.com/s/0mkiufcm85v5w ... 0notes.jpg

Chords only
https://www.dropbox.com/s/dx1gs6wwe4xq7 ... chords.jpg
https://www.dropbox.com/s/qn4nmnhusf0e3 ... chords.jpg
https://www.dropbox.com/s/ymjajeecqkgm0 ... chords.jpg
https://www.dropbox.com/s/tiapdkmujr2lo ... chords.jpg
https://www.dropbox.com/s/jzpfqqh0mvxwp ... chords.jpg

[Groovenut]

So my conclusion is that even the lowly TL074 is a great sub in this circuit and that each of the opamps showed most of their differences when handling single notes as apposed to chords. The closest to the original was the JRC3403 followed closely by the TL074 according to the freq measurements. YMMV

[FiveseveN]

As long as you're taking time to measure things...
It would probably be more illustrative to compare frequency response just after the effect, ideally with a white noise input. Harmonic distortion (with a pure sine input) would also be interesting, though I'd be surprised if the op amps have any influence.

[Groovenut]

I did a series of sweeps through just the effects and the results were similar to what Ive posted so far. Little to no difference between the quad opamps and very little difference between the original RC3403 and the JRC4558. I didn't try measuring with white noise but I would think the results would be very similar.

[Pedal Dan]

Haven't looked inside mine in a while but... I thought the other side of the quad was used for input/output buffers.

[grrrunge]

They are Your point being?

[Pedal Dan]

They are Your point being?

Not much difference. The new Boss DS-1X kills all the old Boss OD's for me. All of them suffer bass loss when rolling back the Vol. Yeas it's digi... But I'm sold.

[mitchelr]

they sounded pretty much identical to me

+1
Any way, there's "something" I like with the 324

I have a very early OD-1 with a 324 chip, this is the first time I have heard anyone mention the 324 chip.
Do you know if Boss used the 324 or has it been a replacement

Ron

[Groovenut]

they sounded pretty much identical to me

+1
Any way, there's "something" I like with the 324

I have a very early OD-1 with a 324 chip, this is the first time I have heard anyone mention the 324 chip.
Do you know if Boss used the 324 or has it been a replacement

Ron

To my knowledge Boss never used the 324 in stock OD-1s. Im no expert but I didnt come across any mention of it in my research, so I would guess it's a replacement part, but it's just a guess.