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zentropa
Gold Member
USA
837 Posts |
 Posted - 05/01/2008 : 16:41:20
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heyas,
i'm attempting to find the right components to install just the seeing eye mod part of the keeley mod. i've done the SEM/ultra for others, but i wanted to just do half of it as i haven't used a drill in over 10 years and would probably lose an eye or finger trying to install a switch :)
i was wondering if there were people who've done enough of these to be able to answer some quickie questions.
i'm guessing the seeing eye mod part is just this?
C1, C5, C12 change to 0.1uF
C2, C8, C9, C14 change to 1uF
C7 220pf silver mica or monolithic
D5 change to 3mm red led
is the 47pf cap jumper needed for only the 1 mode?
also, my gf decided to hop on the computer when i was halfway done and i was working off memory so i think i installed the LED backwards, i'm guessing that's going to make a big difference?
lastly, how important is the material of the 220pf cap? there's only 1 shop in town that has silver mica and when i visited them no one had purchased one since their inventory had gone computerized (~1995) and when they got entered into the computer, no warehouse location was specified... so basically, they couldn't find em. i installed a 220pf ceramic disc for the time being and ordered a silver mica online. is this a huge difference and worth paying the extra money?
thanks. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/01/2008 : 16:56:51
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quote:
Originally posted by zentropa
heyas,
i'm attempting to find the right components to install just the seeing eye mod part of the keeley mod. i've done the SEM/ultra for others, but i wanted to just do half of it as i haven't used a drill in over 10 years and would probably lose an eye or finger trying to install a switch :)
i was wondering if there were people who've done enough of these to be able to answer some quickie questions.
i'm guessing the seeing eye mod part is just this?
C1, C5, C12 change to 0.1uF
C2, C8, C9, C14 change to 1uF
C7 220pf silver mica or monolithic
D5 change to 3mm red led
is the 47pf cap jumper needed for only the 1 mode?
also, my gf decided to hop on the computer when i was halfway done and i was working off memory so i think i installed the LED backwards, i'm guessing that's going to make a big difference?
lastly, how important is the material of the 220pf cap? there's only 1 shop in town that has silver mica and when i visited them no one had purchased one since their inventory had gone computerized (~1995) and when they got entered into the computer, no warehouse location was specified... so basically, they couldn't find em. i installed a 220pf ceramic disc for the time being and ordered a silver mica online. is this a huge difference and worth paying the extra money?
thanks.
This is the SEM from the Keeley site:
- C1, C5, C12change to 0.1uF metal film (104)
- C2, C8, C9, C14 change to 1uF metal film (105)
- C7 220pf silver mica or monolithic
- D5 change to 3mm red led (orientation is important - it must be the same "direction" as the diode removed)
- R39 to 20K
- R14 to 1.5K
- Add 47pf cap across clipping diodes (yes you need this)
I used a 220pF mylar cap for mine. Silver mica is optimal, and I guess it sounds better to a sensitive ear? I can't tell the difference and I'd happily use a mylar/polyester/ceramic in place of silver mica.
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zentropa
Gold Member
USA
837 Posts |
Posted - 05/01/2008 : 17:02:59
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Thanks Laurie,
i saw some other info online that recommended a silver mica for the 47pf cap. not sure if that is accurate either.
i wasn't sure which parts were supposed to be for which part based on his formatting.
i've been playing it as is and it doesn't sound bad, but not as impressive as i remember how the other ones have sounded.
i will finish it up after work. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/01/2008 : 17:07:59
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quote:
Originally posted by zentropa
i saw some other info online that recommended a silver mica for the 47pf cap. not sure if that is accurate either.
I used a ceramic for my 47pF. I'd think ceramic would be OK in both of these spots. Based on where they are and what they do in the circuit I'm reasonably confident that changing capacitor type won't make an "impressive" audible difference.
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zentropa
Gold Member
USA
837 Posts |
Posted - 05/02/2008 : 00:54:20
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thanks laurie,
i got it up and going and it sounds like i remembered them sounding. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/02/2008 : 01:02:25
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| Excellent!! |
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zentropa
Gold Member
USA
837 Posts |
Posted - 05/06/2008 : 06:53:27
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i believe on a different thread a picture was mentioned.
here's my modded DS-1.
i have silver mica caps on the way that will replace the ceramics in the two spots i have them.
i also replaced the LED w/ a yellow one just to have it be a little different and the LED's are like $0.22 locally.
yah, i'm posting a pic of my craptastic solder work. my apartment was recently flooded by an upstairs neighbor so i'm temporarily homeless until they replace all the walls, ceilings, and carpets... so this was done on my gf's kitchen table without my normal tools. i will admit that even with all my tools my soldering is only marginally better :P
price paid for mod parts:
3 x 0.1uf mylar caps $0.25 ea. = $0.75
4 x 1uf mylar caps $0.25 ea. = $1.00
1 x 3mm diffused red LED $0.19
1 x 47pf ceramic cap $0.10
1 x 220pf ceramic cap $0.10
price w/out shipping = $2.14 (i bought 5 sets worth of parts + some extra stuff and shipping was like $2.90 total)
the yet to be installed silver mica caps = $0.95 for the 220pf and $0.56 for the 47pf. i bought 5+ mods worth for w/ $5.15 shipping.
$3.45 per pedal before shipping.
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Edited by - zentropa on 05/06/2008 07:08:10 |
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zentropa
Gold Member
USA
837 Posts |
Posted - 05/07/2008 : 09:37:29
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well, my silver mica caps arrived.
i first swapped out the 220pf ceramic w/ a 220pf silver mica.
the change was minor but noticeable in the gain structure.
the silver mica cap increased the gain on the low end and decreased some extreme high end fuzz. basically, it seemed to smooth the gain over a little and cleaned up the treble.
i then swapped the 47pf ceramic w/ a 47pf silver mica.
this was minor but noticeable. the silver mica cleaned things up a touch and was too big to fit under the board and still allow the bottom to close. i didn't really want the extra clean and put the ceramic back in. i suppose if i could find a 47pf in a different material that would fit better i would probably go with that.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/07/2008 : 10:04:00
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Hi zentropa
Thanks for the pics & your write up.
Just for your interest:
A RED LED turns on at approx 1.5VDC.
A Yellow-Green LED turns on at approx 1.75VDC.
I know you have a really good ear for things like this,
you might have noticed a slight increase in the available level,
as the yellow LED tuns on at approx 0.25VDC greater, than a standard RED LED.
I wanted to write this last night, before your more recent post,
about changing the caps to Silver Mica types, but I arrived home very late yesterday evening.
Regards Dr. Bob |
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zentropa
Gold Member
USA
837 Posts |
Posted - 05/12/2008 : 04:34:18
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thanks dr. Bob.
i realize i completely missed your post... just saw it today.
as for the tonal difference between red vs. yellow, you mean if i had a yellow one in the D5 slot right?
the yellows i got just went in as the power LED to go "hey, this is my modded pedal".
the odd thing is... that the after-market red LED's in place in D5 sound slightly different than using the red LED from the pedal itself.
i liked the sound of the boss LED better in D5 but it was very slight. the boss LED was a tad smoother with less "airy" noise in the extreme treble range (> 8 KHz).
since i got flooded out of my apartment last week i only have access to a solid state amp... and the differences are much more apparent to me because the amp is so f'n bright and shrill.
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leonard d rock
Silver Member
Philippines
301 Posts |
Posted - 05/31/2008 : 03:12:54
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quote:
Just for your interest:
A RED LED turns on at approx 1.5VDC.
A Yellow-Green LED turns on at approx 1.75VDC.
hi dr. bob, does a red LED clip more compared to a yellow one? i tried the yellow one but i think i doesn't clip as much as a red LED?
mabuhay!
LDR |
Edited by - leonard d rock on 05/31/2008 03:14:35 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/31/2008 : 07:48:25
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Hi leonard d rock
That's about right for the Yellow LED
you have about 0.25V (250mV) more level/headroom before they clip.
Stick with the red LEDS if that's the OD/Dirt tone that you prefer.
On a side note:
It would be interesting to try this with White LED's,
as the ones I have here take about 4VDC 20mA before they start to conduct.
And Schottky diodes conduct at about 0.1V, clipping even earlier but you would have reduced level as well.
Regards Dr. Bob |
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leonard d rock
Silver Member
Philippines
301 Posts |
Posted - 06/01/2008 : 06:03:13
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thanks dr. bob.  i changed the red led to yellow and without much listening, tidied up and went to a gig. it was at the gig in the middle of a solo when i noticed i didn't have as much gain and sustain as i had the previous week when i had red leds. i'll try the white ones but i think i have to make some diode adapter first. my pcb looks almost toasted.
mabuhay!
LDR
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Topic |
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DS-1 Seeing Eye Mod vs. Ultra
