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Ken
Copper Member
Norway
25 Posts |
 Posted - 09/24/2007 : 19:49:03
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Anybody tried this?
Keely decided to stop using Burr-Brown opamps in his mod on the sd-1 because this combo gave much better result.
More headroom???
/ken
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 09/24/2007 : 23:40:34
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Read about it briefly, at the time, i was reading more about switching opamps with a toggle since the ins and outs pins are the same. Pins 1 and 7 iirc are the outs, and the rest were stacked and crammed into the ic socket.
Found some good things about stacking opamps (parallel)
This guy (minion)here lists off some cons to stacking them
http://www.diyaudio.com/forums/showthread.php?threadid=108076
and how to get around them
i might have a few opamps kicking around, maybe ill try cramming them in my sd-1 (turned into a ts808)
good luck
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/25/2007 : 16:11:58
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Hi Guys
Interesting.
But I think I need to sit down with my thinking hat on, about this one
(The one with the biggest propeller is always better )
I have seen this done with digital gates, to increase the Fan Out characteristics of the IC.
I guess it's worth a try,
but Analog devices are much more complex that simple gates.
Some simple Dual op-amps contain the equivalent of a hundred or so parts.
I have a schematic & build instructions (somewhere?) for a stereo 11 watt Digital amp, that has a truck load of IC's stacked into a 2 towers of about 22 or so Digital gates to get the 11 watts of output.
I think it was in an British Elector magazine, it was a very unique design.
I think the propeller starting to spin very fast on my thinking hat. 
I just remembered, I once saw a dirt box sch. that used a 3 terminal LM317 1.2V programmable voltage regulator, in linear mode, as a basic op-amp,
to get some gain & to drive a couple of clipping diodes, like the output of the DS-1 (distortion rather than Overdrive)
I still have a copy of that sch. if any of you Techo's are interested
PM me & I'll see if I can locate it.
Regards Dr. Bob |
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WarofGhosts
Copper Member
USA
10 Posts |
Posted - 09/26/2007 : 17:57:13
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| I think David Barber had some info somewhere on his website about this but can't seem to find it now. I have tried it and to me I can hear a difference. Some may like it, others won't. |
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Ken
Copper Member
Norway
25 Posts |
Posted - 09/26/2007 : 20:39:53
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Hi WarofGhosts.
You have tried this and heard the difference.
How was it in you ears?
Did you like it, and what was the most distinct difference?
/ken
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WarofGhosts
Copper Member
USA
10 Posts |
Posted - 09/27/2007 : 16:58:15
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| More headroom and more open drive sounds in dirt pedals. Less compression to my ears. In chorus type effects it tends to lead to more headroom and high end (treble) content. |
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Ken
Copper Member
Norway
25 Posts |
Posted - 09/27/2007 : 21:21:08
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Thats actually kinda cool. Think I�ll try with two new JRC 4558s
I own a SD-1 with a Keely "bastard" mod. A little bit of this and that.
Not happy with the sound. Used a Burr Brown even, but still not happy.
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leonard d rock
Silver Member
Philippines
301 Posts |
Posted - 01/24/2008 : 01:40:57
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quote:
Originally posted by Ken
Anybody tried this?
Keely decided to stop using Burr-Brown opamps in his mod on the sd-1 because this combo gave much better result.
More headroom???
/ken
i tried stacking two 4558s in my 0d-1 and theres more gain and bass on it, IMHO. i also tried it on a boston engineering od-100 (not a boss sound-alike but a look-alike only IMHO) and its now closer to an hm-2 rather than an od. |
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maxm3210
Copper Member
USA
7 Posts |
Posted - 01/31/2008 : 04:22:33
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Hi, I am new at bossarea but I have tried the opamp stacking with good results. I have tried 2 rc4558 and 2 BB. But with good luck I found a really cool pair that work excellent with my modified SD1. Try this one and let me know what you think. One TLO72 and one Op275 the TLO72 is very clean with the whole guitar frequency spectrum. The OP275 is even more cleaner for guitar applications but I have found that it focus the bass more and there seems to be more clarity.
In conclusion you get a tone that is scooped with awesome distorion, the lows are great and the highs but the mid is lowered.
If you do this with 2 4558 you will get more focused bass but I think that there is less high contend therefore, I did not like this mod.
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If you do the 2 BB your tone will get too sterile. |
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op amp stacking
