LM307H Substitutions

For a -65 'script' amp:
Is a NTE937 (Mouser.com # 526-NTE937 (can style))
a direct 'drop-in' replacement for the LM307H?
If 'yes', great.
If 'no', what is a viable replacement (DIP's OK)?
If 'maybe', what mods would accompany it?

Good question.... I personally haven't been backed into a corner where I needed to replace one!
It shouldn't be too difficult to substitute a TL062 or some other other "modern" DIP package for the 307. but if you can get a real 307, that keeps everything original.
Steve

Hi the NTE937 don't work so well. The NTE's have offset null connections, and the LM307's don't. I tried to substitute and w/o the offset null connections the chips freaked out and made some noise. I'm not sure if it works or not, but you could try connecting each offset null pin to the negative supply rail with 56K resistors.

Hi, I have just recieved my Brown Dog adaptors, and have some LM307 replacement IC's to try out. I have a NE5534 (a Mullard sound-alike)that I tried and a some BB samples comming. I do have a BB INA105KP single opamap in 8-DIP to TO-99 adaptor with a 8-DIP socket to switch out different opamps. The NE5534 is warm, quieter, extended lows, mids and highs, slightly more gain and sounds great! I have now the BB INA105KP, and it seems more tube-like, maybe not as much midrange like the 5534, which sounds similar to a Mullard 12ax7 in some ways. I have some other very good opamps samples coming in about a month they say, since they are out of stock. I will post my findings then. These newer opamps are a bit quieter too! Overall the sound is better to my ears. The Brown dog apadtors is basically a small PC board that accepts a 8-DIP IC or socket (very small circuit to solder parts on) with header gold plated header pins pressed into the bottom of the PC board to plug into the MM's TO-99 can type socket. They are well made and seem to stay put pretty well in the MM sockets. This is the most cost effective replacement method, at this time and also allows you to try different IC's in the amp. The TO-99 can types are getting too expensive to get(they are mil-spec usually), some of the BB OPA627 chips are as much as $50 a piece or more! You can get them in a 8-DIP package for about $10-$20, depending on grade quality. This is Audiophile quality and may not apply to most peoples wallets size, but there are some excellent opamaps that would be a instant upgrade for the LM-307. The NE5534 for example is under $1 each, so there you go. I did hear a difference swapping to a BB 1NA105KP (about $5 each to buy, I had some in my stash that someone gave me a few years ago, so I looked up the specs), but I want to try the others out and see what the possibilities are. This BB INA105KP is a better sounding, more tube-like, with more tube-like response, when turning down the guitars volume, it cleans up a bit better and the overdrive is rich in tone. The TONE-QUEST goes on, maybe at some point I will play music again, lol!

Here's some Data for the BB INA105KP for those who might like to translate the specs.http://focus.ti.com/lit/ds/symlink/ina10 5.pdf
and here's the OPA627http://focus.ti.com/lit/ds/symlink/opa62 7.pdf
The NE5534,http://focus.ti.com/lit/ds/symlink/ne553 4.pdf
Maybe this can show some of the info to compare specs for those who can understand it. Some of it is overwheling for me, without everything right there to see and hear.
Ed G.

Here's another I have in my stashhttp://focus.ti.com/lit/ds/symlink/opa27 .pdf
And I found a INA106KP that has a gain of 10...http://focus.ti.com/lit/ds/symlink/ina10 6.pdf
This one seemed to have tons of gain compared to the others. Maybe too much!

I am anxious to try the BB OPA627 and OPA2132 (single opamp). The OPA 2134 is a dual for later MM amps that use duals.
The OPA627 is a surface mount design and needs 2 soldered on a adaptor to work. But have rave reviews about them sounding very tube-like and very high specs, but also very expensive. What I am trying to do is see if the sound warrants the expense, most people may not appreciate the difference and be happy with a less expensive opamp. Why spend more if it is not that big a difference, right? But if it is as good as they say, it might be worth a try. So when the samples arrive, I can post some feedback. Maybe Reed would like to say something too. We might be able to offer some options here. Music Man amps have a lot to offer in value, build quality and tone, as many of us here know, and keeping good sources for parts and upgrades will help keep this Legacey alive! Maybe I'm a bit enthusiastic, but I have had many amps over the years, and built some as well. A Music Man amp has a lot going for them and are becoming a popular amp these days, the popularity is growing. If the tone is not right from what you are hearing, there are things that can be done that are reversable that can get you the sound your after.

Ed, this is so very cool that there are now options available. I just did replace my LM307's with NOS ones and it really cleaned up my sound but they were very hard to get ahold of and now I am curious as to what other tones are available. I for one am going to order these adapters awhile, and I'm very interested in the results that you come up with in trying all these different replacements. Thanks for posting this info.

Hi Dave, yes there are some great upgrades available now. I am inquiring about some various opamps. Reed Obrhom is also working with me on this. We are trying to get samples to try. The Burr Brown's and Audio Devices are great opamps. Then when you find the best opamp, you think "Wow" now I need to upgrade my power supply, well maybe, maybe not... Some hitech opamps might be great for clinically clean but maybe too harsh in overdrive, so theres sweetsopt or middle of the road here too. The BB OPA627 is very hi spec and priced opamp and may work well for clean applications but maybe a slower opamp might be a bit sweeter for lead guitar. I have some NE5534 opamps that are warm, thick and a tad more gain, they sound much like a Mullard 12AX7 and are cheap! I have a stash of less exspensive Burr Browm's (than the OPA627)but some sound ok, some more tube-like and some too much gain or harsh. I like to find an opamp or combination of opamps that give a end result. Maybe for a good Blues/Rock tone, where you want maybe a good medium gain, low noise, good definition, overall great tone more so than hi gain mush, I would go with a hi quality 1st stage input opamp that sets the stage for the first impression. The second stage(after the tone controls)should also have decent gain to to drive the next stage where the overdrive starts to get generated but be dynamic. So maybe a low noise, good spec sound stage, full sounding with a natural clean tube-like quality in the first stage, a warm low noise with good gain in the second stage to push the next stage opamp (3rd) that does not get harsh when pushed into clipping and produces a very tube-like quality. I want my overdrive to clean up nicely when I turn the guitar volume down and to rock out when it turned up. Good clean tone with good articulation when turned down, up slightly with a little dirt, controlled by pick attack, and further on up with the volume up for singing articulate fat tone that sustains easily without having to turn or bend over backwards and fall on your rear to get that feeding back an octave high now sustain like that of Carlos Santana's A barre chord on the end of Black Magic Woman. Or maybe go for that SRV tone... Jimi Hendrix tone, Mr.E.Claptone, Robbenn Ford or Chevy? How about Yourtone... :^) ok I'm dizzy now... gotta go my meds are kickin in, haha!

I just ran across another good sounding and inexpensive opamp, but it needs the Brown Dog adaptor. The LF356N is a low noise good sounding opamp that does not sound harsh, it has a nice clear tone and is cheap! Under a $1 each at this time. The overdrive sound is very rich and not muddy. Sounds somewhat clearer but not too brite compared to the LM307H but with a little more clarity and is internally compensated like the 307. Some opamps I have tried that were high performance and pricey, tend to sound harsh and ringey under max gain settings, but this one sounds pretty good dirty or clean. Comparing between the LM307, the Burr Brown INA105KP OPA27GP and the NE5534. I am still waiting for some other opamps to try out and I will post info on them as well. So far I like the BB INA105KP ($5.60 each) clean and dirty, and this LF356N ($.31 each)clean and dirty, both of these produce a nice clear round Fendery tone that is articulate but not piercing like some opamps. The LM307H sounds warmer since the bandwidth is less than these later chips. But for low noise, a little more bandwidth etc. these are decent upgrades when using the adaptors. I am running the HD-65 through a EV SRO 12" and it has Svetlana Winged "C" EL-34's and a Orange Globe Amperex 12ax7 driver tube. Also I went nutz and put Fairchild FRED rectifiers in the power supply. Next thing will be to change all the electrolytics in the amp even though there is no hum and it sounds good, its probably a good idea to change them out, and it should sound even better yet.

hi ed,
I've run a parts search using the term "brown dog adaptor" (and all sorts of variations of dip 8 to to-99) and haven't come up with any search results. I'd also enjoy playing around with the op amps on my amp in hopes of finding a sound that I really like more than stock. mind you, I like the stock sound of my MM...I just want to educate myself a little more when it comes to semiconductors and op amps. how about a part number or other reference I can follow to see about these adaptors? I'm very interested in your and Reed's investigations--keep us apprised, will you? thanks, pal
ed

oops, found "brown dog"...I spoke much too soon (a common failing of mine). I do have another question however: is the correct part number 020302S?
I gather from your discussion that these ICs can be changed out and "tasted" much as the pre amp tubes in a Fender to find the sweetest set up. oh, another question: does/can one use different types in different IC sockets like we would with different brands of 12A_7's? anyway, I am very interested in what you and reed discover on the subject.
the other ed

I've gotten the brown dog adapters. They are p/n 020601. http://www.cimarrontechnology.com/index. asp?PageAction=VIEWPROD&ProdID=8
I soldered 8-pin IC adapter sockets to mine so I can swap opamps but haven't ordered any opamps yet. I was waiting also to see if Ed had any other good choices. I did do a little online research and maybe some other candidates might be OPA2604, OPA2132, AD8610, AD820. Any of those on your list?

I had no love ordering the corrected part number from cimarron tech; seems their ordering process was down at the time. I'll try again tomorrow. thanks for the correction, david. my list is composed of those numbers both you and ed have compiled (excepting the $50 opamps, I have serious doubts about my jumping on 7 opamps in the $20 price range for that matter).
[right now may have developed a very serious problem elsewhre in my amp...last night my amp went down during a gig from a most probable dead short heater circuit...btw, I am also an electrician by trade; early retirement three years ago.
ed s.

my brown dogs are on the way as well. let's find that area of heaven known as "tone nirvana."
the other ed

Hi guys, glad you are getting the parts together, sorry I have not gotten back sooner, been busy. I have some old LF356 single opamps that sound pretty darn good in the HD preamp. Its a low noise compared to the LM307H, and its a tid briter/clearer, maybe more headroom, and the slew rate is not real high, but it is articulate enough to sounds like a fresh 12ax7, haha! Like a new set of strings, and it is not harsh like some opamps I have tried, still waiting for the Analogue Devices opamps and the othere Burr Browns to compare, I have a feeling the high quality/priced units will be quieter and faster responding, and may sound great in clean settings, but maybe a little harsh in overdrive. I like a little slower responding opamp for overdrive but not too slow, the lower quality opamp seems to have a certain sweetness for overdrive tones, but I am looking for a little more bandwidth, lower noise and good overall tone, at this time the BB INA105KP sounds very tube-like and works pretty good in the HD, also the LF356N sounds very good as well, have to play more with them to hear the differences. The biggest difference is price. The INA105KP is about $5 each! The LF356N is about $.31 each! So there you go, the LF356 is an improvement and is internally compensated like the LM307 and is cheap. I had some here to try, thats why I posted them. I have some OPA27GP's that sound good but are bit harsh to my ears. They are very low noise and good specs, but even set up clean, the tone is sharp to me. So I am thinking for guitar, there will be some opamps that will work well inexpensively and are upgrades to the old 307's, with the Brwon-dog adaptors, I am very curious how the BB OPA-627, the AD644 and a few other so called audiophile quality opamps work out. Either they will sound very tube-like or too clinically clean for guitar. Its like saying I need hifi stereo speakers for my guitar amp, they are more efficient and are more full range. Well we know what happens when you plug into a PA board, the sound is somewhat thin compared to the narrow band guitar amp/speaker, since the guitars frequency bands are narrow in the midrange and not really extended in the treble and bass ranges, so that why I am thinking that for guitar, you don't have to go crazy with super duper opamps for guitar. For instance, there was a post here on a RD-50 and the guys who were trying out opamps, had either TLO72's or LF353's in their RD. They ended up preferring 4558's for a more bluesy tone. The tone is less brite or transient and has a slower slew rate, which sounds great for blues guitar, if thats what you looking for. The TLO72 and LF353 are J-fet opamps so the input has a fet there on those, and the sound has more of a bite to it, maybe too much for some, depending on the guitar, pickups and player etc. If your guitar is on the dark side the better spec/performance opamps might work well here. I even tried some old 1458's, they sound very sweet and the tone opens up a bit, maybe a little noisier, tad lower gain, not as much bandwith (treble and bass) but the sound is right in the range of guitar. Very open sounding. So I tried combinations of the different opamps, like a BB OPA2107 in the first stage, it sounds very tube-like, but slightly on the brite side, more gain, fuller bandwidth etc. good for cutting through, more Boogie sounding for example, faster responding. Then I had a NE5532 in the mixer stage where the two volumes (clean and limit Master)are. It warms up the tone, making it fatter and a bit bigger sounding overall. The driver stage seems to like the TLO72 with this combination. So this tone might be good for the player who is trying to get more of a Marshall-like tone with a toothy bite! Good for Gary Moore type tone, or similar to a Plexi... Also its important to try a Mullard, Amperex, Bugle boy, and maybe the GT 12AX7M in the limit channel. Very nice combination for this tone. But if your more into a classic Fender overdrive, the 4558 or 1458 sounds good in all stages, for lower gain applications. I am trying the 4558 opamps now and a TLO72 in the driver. It has just enough sag when picking the note hard for blues, slower slew rate too, but no J-fet input... It has decent gain and does not get harsh. Remember these sounds will be different in a band/gigging situation. A sweet warm pretty sounding amp in the bedroom, will not usually cut through the mix in the club setting, it usually turns to mush, but if its slightly on the brite side, it will usually cut through well in the mix, these things you have to just try yourself to find what works best. An good example was my Friend Gil Ayan, who built some very nice Dumble* clones and one of the first amps, he used caps in the overdrive channel that sounded way huge and blusey at home, at the gig, it sounded ok, but he had the oppertunity to work on a Real Dumble* that had smaller value caps in it, less bass in the overdrive. Well he really did not give much thought to it till later, he for some reason swapped out the caps for the smaller caps, and the drummer commented "That was the shit!, whatever you did to that amp!" So you see the less bass more treble in that case helped his solo's tone to come through more, he said the high notes would sing more, and the bass notes did not buzz after that change. It also helps sustain/feedback effects, since not too much bass weighs the high frequncies to pull the notes into the octave up feedback. A very sensitive circuit.

Anyone know the phone # for Lloyds of London ??
I think we should all pitch in, and have Ed's ears insured for a couple Mil or so.
I've had wonderful conversations with both Ed S. and Ed G. or the phone. Two excellent resources and inpirations.
I'm supposed to be doing my share in the "Opamp of Forturne" contest. I will try to order some of the Analog Devices AD 744 (single amp), and AD 746 (dual amp) chips in the near future. (I know, I've told Ed I would do it 2 or 3 weeks ago). These are supposed to be the neaarest thing to the Burr Brown OPA 627's for less cost.
(For a dual OPA627, you have to get the appropriate Browndog adaptor that accomodates 2 627's soldered onto one adaptor, to make dual opamp configuration).
As Ed says, these are consdidered to be the "cat's meow" for audiophiles, but they may not be the best for guitar amps. We'll see.
"Lower cost" is still relative. The Analog Devoces 744/746's are $3 - 10 ea, depending on quantity purchased, quality grade selected, type of chip body. Not cheap like $0.31, that's for sure !!!! But the Burr Brown OPA627's are $30 - 40 ea, and if you want the 1458 equivalent, i.e. a dual op version of the 627, you're lookin' at $70 - 80 per chip, including BrownDog adaptor. Yowwsa !!.
Thasnks for keeping it going, Ed and Ed. (The Ed Brothers) (Just kidding)
Reed

Thanks for sharing Reed. can't wait to hear the results. Its fun getting to try out opamps and be able to have a replacement for these sweet amps! Keep up the good work buddy ;^)
Ed G.
Ed S. Brother :^)

okay guys, I'll bite. and, by the way, how ya doing reed? sounds like you guys are doing some fine work on the op amps...I have thought about whether it was possible to voice the amp using different ICs...very cool guys.
I, too, have my brown dogs in the mail it is just that I need to sort out another minor problem before I can join in the fun. welcome to the family, ed (or is it you welcoming me into yours? this is all very confusing:^)
ed s.

Thank you Ed S. I like to try different things like this, and have read where some folks have changed out the opamps in their overdrive pedals to get a desired effect, maybe a sweeter tone, more bite, maybe a slightly more compressed tone, etc. All adds up to get you a better overall tone, to inspire the senses. David Gilmour is a good example of that. Well I got the AD744ANZ, AD797ANZ, and the AD823ANZ (dual opamp for later MM) opamps yesterday. Well in a A/B test and my 47 year old ears, The AD797 opamp was twice as loud when they were awakened from their package and pushed into the world of tone demanding suroundings. Within a couple minutes the opamps started to fart and burp compulsively, and where pulled out, maybe they could not handle the company of 30+ year old components, haha! The sound was way huge while they were in their moment of glory, but they pooped out in that circuit, maybe the voltages were not right for them? So then I put in the AD744ANZ... they are faster, full sounding, and have some punch to go with the party, but I A/B'ed them with the LF356N, and I personally like the LF356N better for clean-dirty sounds. The attack is not so piercing and I believe the slew rate is a little lower, has a little give in the pick attack, great for guitar! The OPA105GP sounds good too, has a tube-like toothy bite. So for now I have the LF356N's there. At $.31 each, you can't go wrong... Noise-wise, I had a hard time telling much difference. The power supply probably puts out its own noise in to the sound.

Here's a datasheet on the LF356N, note the High slew rate of 5V/ushttp://www.chipcatalog.com/Datasheet/BA9 1033415F9A5D1BBC22C7F33552AEE.htm
The slew rate on the AD744 is,http://www.analog.com/en/prod/0,2877,AD7 44,00.html
75V/us Slew rate. A little faster? Maybe too fast for me, lol
Here's one for the INA105KP unity gain opamp.http://focus.ti.com/lit/ds/sbos145/sbos1 45.pdf

Hey Guys,
I might as well just keep my amp out of it's cabinet for awhile.
Please bear with me, since I'm not an electronic tech. I'm trying to understand the preamp section. Looking at the schematics for my HD130 it looks like IC-1 and IC-2 are for channel one and IC-3 IC-4 are for the second channel. Then they both go through IC-5.
My first question. Would you want the more dirty sounding IC's in the the first stages and a more clean sounding faster one in IC-5 ? This is my train of thought but please tell me if I'm way off base.
Also I'm seeing 2 IC-6 LM1458 on the schematic
which I do not see on my amp. What are they for?
I'm thinking of maybe ordering 2 opa604's for the one channel and 2 5534's for the other channel. And maybe an opa134 and a opa627 to swap for the final stage. Any opinions on this? I've been reading alot on the DIY guitar amp forums and these seem to be the popular choices for guitar amps. I'm kind of anxious to try something since I have my adapters ready.
BTW I did have a chance to play through my amp for a few hours last night. Since I replaced the tubes, caps, and LM307's the amp is sounding pretty darn good. Anything else will just be icing on the cake.

First of all; a self-correction regarding the prices of Burr Brown OPA627's, that I spouted off about a few days ago (see above). Prices on Digikey for the OPA627's range from "only" about $18 - 35, depending on chip body/pin mounting type and quality grade. BTW, they do have a OPA627 in a TO-99-8, can type, 8 circular arranged pins, that would plug right in to the sockets in the HD 65/130's, with no need for a Brown Dog adapter, but those are the ones that are $35. So, prices are a little less than I quoted above; still not cheap, and again, if you are making a dual opamp version using OPA627's, you have to buy 2 surface-mount 627 chips (since the OPA627 is a single amp opamp, and I haven't come across a Burr Brown model that is specifically a dual amp version. But I think Ed mentioned above that he has found one), and buy the correct Browndog adapter, solder the two chips to the adapter. The double opamp versions would be needed for the HD 75/150, and others>>, which use LM 1458's in the preamps, in a 8 DIP socket mount in the preamp sections, and driver sections, as well.
Which brings me to my second comment, addressing Dave's preceeding question;
(I essentially am passing on what I have learned from Ed G., who "walked me through" the schematic of the HD 130 and HD 150, both of which I have. (Note, I have only the "Bass" medels of these two amps, i.e, non-reverb/tremelo circuits, so I know there are a few (2?) more chips in the reverb/tremelo circuits. You'll have to call Ed G. for yourself, and get the "skinny" on those parts of the circuits). Anyway, thanks Ed for the insight, I'm passing it on, as I understood it. Please add, embellish, amplify (hey, there's a concept !!), and/or correct, at your pleasure !)
Anyway, Dave; Be aware that in the same PDF document that is the schematic for the HD130, there are two schematics; The first one is for the original circuit, using the 12AX7 tube as the Phase inverter, in the Driver Section.
The second schematic on that same document, is for the later HD130's, where MM had switched to a Solid State Driver section. The two IC-6's you see, both listed as LM1458, are the two inner opmams of the LM1458, which is a "dual opamp" chip, i.e, two discrete amplifying circuits in one chip. The two amp sections of this chip are therefore the 2 "halves" of the driver stage, that drive the tubes, in a "push-pull" design. (I still don't have a real good "handle" on how a "push-pull" tube design works, but that will be "next semester's" topic)
So, I assume your amp has the 12AX7 driver stage, and thus you would not see the LM1458's in your chassis, and would want to reference the schematic that shows the 12AX7, not the one that shows the 2 halves of the LM1458.
I hope I've not just inadvertently auditioned for the role of the "poster chiid" for the axiom, "A Little Knowledge Is A Dangerous Thing" ^!@%$
Reed

All of the technical interplay and self-help going on here is extremely gratifying to find! This is the reason I put this site together in the first place... so we can all benefit from each other's individual efforts in keeping our MM amps alive for yet another generation to enjoy (after we have some fun with them, of course).
I have been swamped in many areas of my life and I only check in from time to time but keep up the good experimentation so I can learn what works too!
As has been stated before, I can't wait to get back to playing my amps instead of working on them. However, in my case it is also true that I can't wait to get some time to WORK on my amps as well.
Steve

Hi Dave, whatever you can get from sample suppliers etc, to try, that has the proper pinouts for your amp. Yours has the LM307H, correct? Then the 1458 will not work as Reed said, since a 1458 ia dual and the 307 is a single. As far as dirty in the first stage, I would think it would be a little more difficult to clean up with your guitar volume control if theres too much gain up front, but a good way to think if you are wanting to control the overdrive from the guitar better, is take for example the Trainwreck Express amp, it is designed to distort from the powertubes first, the PI second and the preamp third as a push, this is exremely guitar volume friendly! But the amp will start to distort with the volume set at about 9:00! THey usually set the volume for the lead tone say maybe 11:00-2:00, ant turn the guitar vlume down for clean chimy cleans. Check out the Kometamp site and listen to the downloads. This is just an example of how that scheme works. Also having too much gain up front might tend to be more noisy, so I would go (personally) with a good gain, low noise performance opamp like a LF356N or the OPA105KP or similar opamp in the first stage, it doesnt hurt to try as many as you can as long as they have similar specs and the pinouts are correct. I have tried the NE5534, which is a higher gain, fat sounding opamp, but tends to be a bit dirty all the time, but does clean up fairly well, it depends on the tone your after and you gear, guitar taste, etc. So try as many as you can and please report back with your experience, it is greatly appreciated! I have been trying to get the Burr Browns but TI is giving me the run around saying they have not heard back from me, as I have sent numerous emails with the request for OPA627's and a few others to try out, I even called and left a message on their wonderful automated message system! The rep only emailed me back to say, " I have not heard back from you, you must have solved you opamp needs" I keep emailing them and this is what I get, maybe you or someone else will have a better luck? I am pretty happy with the LF356N, they are inexpensive, the sound very nice, from clean to distortion and in between. Not harsh or ice-picky as some of the higher priced opamps sound for guitar, my personal feelings anyway. Each individual will probably experience a different effetc though. I suggest to experiment as Steve said, and please let us know what you come up with, but use our experience as a guideline maybe, to help you decide what works best for you. I find that the 3rd stage is where most of the distortion is generated and tyen it pushes the 12AX7 into a sweet overdrive. Loof at the Clapton mod schematic, and the 3rd stage is where the overdrive is boosted, the 4.7k resistor that parallels the stock 4.7k does allow more signal through and works really well, I have one on a push/pull pot so I can go from stock to boost with the push/pull switch. I only addedv the 4.7k resistor to the boost mod, it calls for a 1uf cap paralleled as well, but I could not hear any difference when trying it, the 4.7k was the biggest audible imprevement there, so far.

Hey Guys; I hope you don't think this is too "off topic", but it just makes me love "that sound" of a "singing amp" so much !!!
It's a short segment from NPR's All Things Considered, about two videos on Youtube.com that are IMHO, knockouts.
The first one, from "FunTwo" has a tone to die for !! (not to mention, licks TDF too)
The second one is acoustic, so just a nice compliment for the first.
I invite, encourage, demand !! (??), that you listen to the NPR segment (it's only 3 minutes). If that whets your appetite, click on the links for the full videos, in particular, apropos this Message Board, the first one (FunTwo).
If you watch the video(s), and don't get a smile on your face at least once !!, I'll refund your picofarad.
And if Steve says I have to, for posting this music link, I'll write "I Will Not Stick My Fingers In A Music Man Chassis Without First Discharging The Filter Caps" 1000 times on the blackboard.http://www.npr.org/templates/story/story .php?storyId=5725826
Enjoy, Reed

Greatest thread ever! Thanks for the scientific exploration and reporting, very nice work.

I have uploaded a .doc with links and prices to the various IC's listed and related items. I concentrated mostly on single channel op-amps but the sellers carry dual and quads without exception. I had trouble finding the BB opamps suppliers in the models recommended: any suggestions would be nice.
I ordered the brown dog adapters and the NE5534 and LF356N. The whole project, including shipping, for five of each IC's with adapters cost less than thirty dollars.
The problem that lead me here is a failing LM307 on the reverb send.http://www-personal.umich.edu/~tdunham/M usic%20Man%20Opamp/
One file is .DOC and one is PDF with links intact.

The BB opamps will be a TI product now, since Texas Instruments bought BB (Burr Brown) out some time ago. I find that BB opamps are very flat response opamps and good for that purpose. The LF356 is very good sounding and very articulate, where a 5534 is warm and fat like a Mullard ECC83, mix and match opamps for your own rolled reciope... The Browndog adaptors are great!

Hi Ed,
I really like the LF356's and found the 5534's kind of noisy in some positions but still a good rec. I'm running LF356's in the signal path with the 307's on the effects. Surprisingly, the 307's are the only IC that work in the non-master channel.
Thanks again for the info, very fun satasfying project.

I am installing new op amps into my old 12AX7 HD130. I will report back. I will have 5 AD843 op amps; 1 LM741CN; 1 OPA627 can to interchange.
I will be using 5 out of the 7 available. Let's see what I come up with. Ohhh.. I have reduced the bass channel pre-tone bass/mids cap from .47 to .22uf orange drop - C5 on my schematic.
I am aiming for 2 slightly different channels directed towards the guitar freqs. I want to use an A/B stomper with varied effects going into the seperate channels. I will atempt to get a stronger mid/high response from the bass channel through its soul rather than a bandage type bandpass filter. Uhhhhh...other than the cap change-out.hehehh.Commencing the experiment sooonnn.....

Hi Guys,
Are you all aware, that the substitution of op amps, will actually affect the intensity and speed of the tremolo effect in the MM One Thirty amp, basically weakening the effect in a negative way! I went ahead and bought all the op amps recommended and tried them, only to realized it too late. The LM307H was the only one which kept the warm tremolo effect unchanged and strong.

Did you adjust the trim pot for the Tremolo on the circuit board? It may need to be tweaked to the opamaps. What Opamps did you go with?