Taperssection.com
Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: Todd R on May 22, 2005, 06:21:16 PM
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Ok, wife's away, time for the taper geek to play. Spent some time this afternoon working on the SBM1 I picked up recently. Gave it a good going over with modifications. 3 to be exact:
1) Coax output mod. I've done a few of these, and always seem to be doing something different. For my original one, and for one for jbk, I added a female RCA coax out on the (cutoff) 7pin dongle. For Tim (now in the hands of Scott from the CO Crew), I put RCA coax jack right into the side of the SBM1, so there was no cable at all. I really like this option, but it was a pain to do, and the way it is wired up, you'd need to unwire the coax output to pull the SBM1 guts out to work on it -- which seemed like a pain. This time around, I followed leegeddy's route and totally took out the 7 pin dongle and replaced it with a coax cable with a male RCA plug on the end. I didn't have the right raw 75ohm digital cable lying around, so I used a hacked 75 ohm video cable that I did have in the junk box.
2) Optical out mod. Did this based on the input of Doug Oade:
http://www.oade.com/Tapers_Section/Forum/dcboard.php?az=show_topic&forum=105&topic_id=119&mode=full
This should be real nice when using the SBM1 with a JB3. Once again, it's not like I planned ahead to do this stuff, so it was time to rustle up an optical transmitter. Pulled one out of my Aopen 850D digital soundcard daughterboard. I'm only using the coax out on this, so I figured it was a likely culprit to steal from. A little de-soldering later, I had my transmitter. Needed a 0.1uf capacitor, and found one I could steal from an old car amp I've been cannabalizing in the junk box in the garage. Really that is all that is necessary in the way of parts. Since the SBM1 was already totally disassembled from the coax mod, I just needed to take out the 7 pin socket off the main board and then replace it with the optical transmitter. Wiring it up was a bit tedious due to the size of things, but there is just enough room to get the wires and cap in there. I needed to file the opening on the case just a tad more and use some epoxy to hold it in place, but the transmitter I stole from the soundcard was a pretty good fit.
3) Line stage upgrade mod. The same mod I've done now to several SBM1's now. My take on the line stage (analog stage) upgrade that Doug Oade does. Upgrades the line input of the SBM1 so it sounds nicer. I really should figure out who all has these ToddR-modSBM1's or who had them. I pretty sure COtaper Zach still has one, though I haven't seen him out taping for 3 years. My original one I did for myself has found it's way back home and Simpy owns it, though Tim is going to be using it. Did one for JBK that he promptly got rid of, don't know to whom. And I did one for Mr. Twister, and god knows where that has gotten to after he sold it. I wouldn't mind getting some feedback from those who have run it on how they think it sounds.
Sorry, I didn't take any pictures along the way, though leegeddy has excellent ones of the coax mod in the archives (+T for those Marc!). Below are a couple shots of the coax mod and the optical mod.
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+T for the SBM-1 mods. Care to give any insight on your line stage mod? Opamp choice, cap replacement, etc...
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+t Thanks for the couple photos. Would you be interested in doing the line stage upgrade mod on another (mine) sbm-1?
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+T todd, youre freakin amazing w/ yopur work too ;)
now i may have to pick up an sbm1 and BEG you to do that to it ;D
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nice work as usual todd
I really want to run an a/b between scott's oade modsbm1 and the toddr-modsbm1 that I'm borrowing from simpy. we've got identical rigs, we really need to make that happen
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very nice Todd....quite impressive!
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So if I pick up a SBM-1 would you mod mine......?
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Thanks guys! Now I just need some shows to hit so I can try this thing out. Margo called and asked what I've been up to today, so I told her. Turns out I never admitted to picking up the SBM1 in the first place. Got to learn to keep my mouth shut! :-X
dB--as you guessed, op amp replacement is the biggest factor in improving the sound. I haven't messed with the capacitors. I thought about this awhile back, and think I'd like to stick to my decision not to reveal which exact part numbers I used. Personally, I'm afraid if I did there'd be folks who would just mindlessly swap in the parts I chose. I think the magic of diy is for people to learn about things and especially for folks to try out new things and find what sounds good to them. I'd like to encourage a wider variety of mods so there will be different flavors of gear out there, and don't want to encourage people just to copy what I've done. There are many threads both here and on the Oade board (esp the old one) where people talk about op amp replacement options. Some op amps that have been mentioned by Doug Oade, myself, and various audiophile sites (including Jon Risch's site, an excellent resource) are: the Analog Devices AD712, the Burr-Brown OPA-2106 and OPA-2132, the National Semiconductor LM6172 and the Analog Devices OP-249. When selecting op amps, make sure they are drop in replacements for the ones you're getting rid of. Make sure they also operate on the voltage that is provided on the board you're modding (I believe the power rails of the SBM1 are -6v and +6v). Make sure the replacement op amps don't draw more quiescent and operating current than the op amps you're replacing. After that, look for ones that have low noise levels, have good CMRR, have a fast slew rate, etc. Any of the above listed op amps are probably good candidates for the SBM1, but be sure to double check the data sheets to confirm. Hope that helps!
dgodwin--pm sent.
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sweetness, todd!!
many thanks for all the info you've provided for the coax mod. i couldn't have done it without it.
marc
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dB--as you guessed, op amp replacement is the biggest factor in improving the sound.
I was planning to install one of the Mill-Max low profile sockets to audition one of the opamps you mentioned and a couple others which have been suggested to me.
Mods=hours of entertainment... ;D
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Very nice piece of engineering Todd! That optical mod makes me wish I hadnt sold my SBM-1 :'(
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todd
great work.
i have one of your mod-sbm1 here in philly...we exchanged emails back and forth when i was purchasing it...that was a year or two ago. you were very helpful. i upgraded from a stock sbm-1 to your modded sbm-1. it is a line stage mod only. and the 1/4" mic inputs still work. i am extremely pleased with the unit.
i m pretty sure i know what op-amps you used, but your secret is safe with me. 8)
let me know if you would perform the optical output mod (which replaces the 7pin in) on the my unit. i would pay for shipping, parts, and whatever you feel your time/effort/labor is worth.
thanks again.
oh, one more thing. i have always given credit for the mod in my seeds. in my source lineage for shows i seed, i have been using:
pre-amp > Todd_R mod-SBM-1 > recorder
a few times i have used TR mod-sbm1
is this ok, or would you prefer something different
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How about a line-stage mod to an M1 and skip the SBM completely. Can be done, but damn there's little room for error on that PCB...
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can you run optical & coax out at the same time??
loooks nice!!
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anyone know where i could find the panasonic TOTX178A that doug talks about?
i tried digikey and mouser but neither carry it.
also, is this really panasonic and not toshiba? i found a toshiba optical transmitter with the TOTX178A code.
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can you run optical & coax out at the same time??
loooks nice!!
Yep, it'll definitely be able to send out optical and coax signals at the same time.
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How about a line-stage mod to an M1 and skip the SBM completely. Can be done, but damn there's little room for error on that PCB...
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Could be possible, I don't own an M1 so I don't know what the design is like. One thing to note though, the A/D of the SBM1 is an upgrade from the M1. The M1 takes a 20 bit signal and uses the basic tdf (triangular dither function) to dither to 16 bits. The SBM1 uses 24 bits initially and then uses sony's proprietary Sony Bit Mapping dither function to dither down to 16 bits. The SBM dither process seems to be much more highly regarded than the tdf dither routine.
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Ok, I've had several people now inquire about me doing mods to their SBM1's. Previously, this hadn't been something I wanted to get into. But at this point, it looks like Doug Oade is no longer doing mods, so there is no one available to fill the gap like there was before. And at least at this point, I am unemployed so I've got a lot more time available to me. Bottom line, I'm leaning towards doing any of the mods I did to my SBM1 (coax, optical, line-stage) for other folks. I spent some time this week looking into parts, etc., but need to spend a little more time on it. Once I get things all figured out, I'll get back to the people who have inquired so far.
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Todd, is it possible to bypass the SBM function and get a straight 24-bit output from the device? Is there enough room above the noise floor of the unit to even make this worthwhile?
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anyone know where i could find the panasonic TOTX178A that doug talks about?
i tried digikey and mouser but neither carry it.
also, is this really panasonic and not toshiba? i found a toshiba optical transmitter with the TOTX178A code.
http://www.datasheetcatalog.com/datasheets_pdf/T/O/T/X/TOTX178A.shtml
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Todd, is it possible to bypass the SBM function and get a straight 24-bit output from the device? Is there enough room above the noise floor of the unit to even make this worthwhile?
I don't really know the answers to that. But I seem to recall reading a post by Doug a long time ago on the old Oade board saying the chip that is used by Sony could be used to provide 24 bits. I have no idea whether the rest of the design/signal path of the SBM1 would allow for 24 bits though. The SBM1 when it was released was an amazing piece of portable gear for providing high quality 16 bit data. Even today after some tweaking the SBM1 design can really hold its own over modern designs using present day semiconductors at 16 bits. But my guess for 24 bits it wouldn't be worth it. I would imagine that as you say, the noise floor of this whole design would not be low enough to justify modding it and using it as a 24 bit encoder.
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+T todd......here's to #400 :)
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Thanks, Cap'n! Bakatcha. :)
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Ok, I've decided to go ahead and perform line/opti/coax mods to SBM1's for people who want them. I've contacted those who have already expressed interest. If you're interested in one, drop me a line and I fill you in on details.
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todd...are you busy one day this weekend?
id love to come up for a few hours for jb3 repair attempt before you get swamped by SBM1s!
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This weekend is probably going to be pretty busy for me, holiday weekend and all. Weekdays are better -- maybe sometime after work you can swing by?
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Very cool ! +T
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Ok, I've decided to go ahead and perform line/opti/coax mods to SBM1's for people who want them. I've contacted those who have already expressed interest. If you're interested in one, drop me a line and I fill you in on details.
:), +t Todd R, Those mods look great!
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I can see it now....coming soon little stickers on a bunch of SBM-1's "This unit modified by ToddSounds". Todd, no shit you should try modding a UA-5. Since the Oades will only modify their own you could make a tidy little profit on modding ones for folks who dont have Oade units (like me 8) ) as well. We should get some of the CO folks to go in on one off ebay for you to experiment on, if successful we could have a community unit that the CO crew could use in times of need. Just thinking outloud.....+T again :)
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i have an extra un-modded UA5 that Todd could use to experiment with (if he wants it).
If it gets fried, no biggie.
If it ends up working out, we coulld put it in the loaner program and pass it around and run some comparisons.
send a PM if you are interested, Todd.
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+t for the work...
Sorry, I didn't take any pictures along the way, though leegeddy has excellent ones of the coax mod in the archives (+T for those Marc!). Below are a couple shots of the coax mod and the optical mod.
where? - i think it was my unit he was modding, and i would love to see them..
the pics of that finished unit are below...
link (http://photobucket.com/albums/v405/macdaddy_47/rig/sbm1/?action-view&slideshow=true)
coming soon little stickers on a bunch of SBM-1's "This unit modified by ToddSounds".
mine didnt get an oade sticker :(
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The pics leegeddy posted are in the Archive:
http://taperssection.com/index.php?topic=2232.msg545741#msg545741
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thanks - i guess that one was simp's...
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So is there any feedback from someone who had this mod performed by Todd? I don't doubt the abilities, I just want some opinions.
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Todd,
If you could get the UA-5 upgrade info from Doug, that would be awesome. Last I knew, he was not doing any more mods to stock UA-5s. He's only maintaining the warranty on the originals that he modded. I'd love to get a Transparant Plus mod, but Doug won't touch it because its not an original Oade digi-mod. Bummer. :-\
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Todd,
If you could get the UA-5 upgrade info from Doug, that would be awesome. Last I knew, he was not doing any more mods to stock UA-5s. He's only maintaining the warranty on the originals that he modded. I'd love to get a Transparant Plus mod, but Doug won't touch it because its not an original Oade digi-mod. Bummer. :-\
When and where did you get this info
Last I heard Doug is still modding UA-5s bought through him. He doesnt have anymore in stock and can not get anymore cause they are out of production.
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I think you both are pretty much saying the same thing. Doug will change the flavor of w-, p-, and t-mods of the units he has sold, or will do an upgrade to a digi-mod he has sold. But he isn't selling new ones (out of production) or modding existing units he did not sell.
At any rate, I doubt Doug will provide any info on the exact parts he used for these mods, since those parts may well be used on mod 410s or mod FR2's or whatever he's got up his sleeve. Time permitting, I might look into mods to the UA5 myself, but not at this point.
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Doh....thats what you get for reading through to fast and doing something else at the same time
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I think you both are pretty much saying the same thing. Doug will change the flavor of w-, p-, and t-mods of the units he has sold, or will do an upgrade to a digi-mod he has sold. But he isn't selling new ones (out of production) or modding existing units he did not sell.
At any rate, I doubt Doug will provide any info on the exact parts he used for these mods, since those parts may well be used on mod 410s or mod FR2's or whatever he's got up his sleeve. Time permitting, I might look into mods to the UA5 myself, but not at this point.
Thanks Todd! I'll check back with you on the tail end of this calendar year. +T
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todd, did you make any mod SBM1 with a hardwired coax dongle in place of the 7pin dongle..
just wondering.....
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Todd, you prolly already know this, but keep a list of what you did to what serial numbers!
+T on the mods - that optical output mod is going to be the rage!
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I think you both are pretty much saying the same thing. Doug will change the flavor of w-, p-, and t-mods of the units he has sold, or will do an upgrade to a digi-mod he has sold. But he isn't selling new ones (out of production) or modding existing units he did not sell.
At any rate, I doubt Doug will provide any info on the exact parts he used for these mods, since those parts may well be used on mod 410s or mod FR2's or whatever he's got up his sleeve. Time permitting, I might look into mods to the UA5 myself, but not at this point.
There was a whole thread about the parts he used for the UA-5 mod on TS somewhere. Ill have to dig it up.
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Some of it is here http://taperssection.com/index.php?topic=28422.0
With links to the Oade board on that thread.
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