| MrGuitardeath |
I've recently started building my own gear and have discovered the diversity of op amps. I am currently wanting to upgrade the TL072's in my Crate head.
It uses 5 and I was wanting something much higher end but I'm not satisfied with the specs of the chips people are recommending me.
The TL072 has a typical slew rate of
16 V/uS and the AD825 I was considering is 140 V/uS ! The gain bandwidth difference is about the same. Can anyone tell me if the AD825 is a good idea and if not feel free to make suggsetions.
I'm not really interested in the NE5532 or NE5534 which seems to be the popular ones guys swap the TL072's out for. |
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| sangram |
Really, you should swap out the opamps for a tube preamp stage, if you ask me.
I think you will have to experiment to find the tone you want. I would think that the experimentation in musical instruments (yes, an amp is as much an instrument as anything else) should be the quest for tone/colour, instead of hifi where we seek to eliminate colour as far as possible. Therefore the same methodology may or may not be beneficial.
Of course, the NE 5532 is a slight upgrade and the ones you are quoting seem even better but you should actually hear the sound for yourself. It is possible that you may actually like the sound of a 'lower end' chip a little more.
Best is to buy as many different types as you want and decide on which one (or combination) you want. |
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| eplpwr |
I've built some stuff using TL072, since they are very cheap. After
finishing my project, I replaced the TL072 witch OPA2134's and
the sound definitely improved. BTW, I had sockets on my board, making the swap really easy. As opposed to NE553x's, OPA2134 has FET inputs, and thus very high input impedance like the TL072's.
You could also look at the OPA2132, which is less common, but has slightly better specs than the OPA2134 - at double the price.
Good luck with your tweaking.
/ Pelle |
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| MrGuitardeath |
Hey thanks guys.
I already use the solder tails(sockets) and a tube pre-amp stage is out of the question here. Besides, it's already the best tube emulation amp on the market.
I ended up going with OPA2604's after trying many other suggested op amps. They are a bit smoother and richer sounding than the TL072's but not by a whole lot.....not like they were in my distortion pedal!
Anyway is there anything better out there?
I was still considering geting two AD825's and using a two single op amp to dual op amp converter that is also pinned for use in a DIP-8 socket. Maybe even AD627's. It won't be cheap though. My amplifier head uses 5 dual op amps. |
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| bobp |
I am newbie on this list so hello everyone.
What I would like to do is to upgrade Kawai PN100 digital piano
some 2 years old.
I am seasoned hifi tweaker and not solder-gun shy but never tried my luck on anything like this.
Any ideas or pointers to information are welcome.
TIA |
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| jazzpeter65 |
HI!
I have tried ouy dozens of opamps for guitar use. I prefer opa2604. It's smoother than the rest. Have tried opa627 aswell. It's too cold and exspensive too.
- Peter |
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| MP2OLD |
| I am also looking to upgrade op amps. I am rebuilding an ADA MP2 (tube pre-ampw/ effects)with better resistors, caps, etc. This unit has a multitude of op amps. I would keep the manufacturers in business just trying them all out. Anyone have any experience in what sound quality changes different op amps produced?:cool: |
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| jazzpeter65 |
If I were to build an ADA-clone I would go for the OPA2134 from BurBrown. Low noise, fast, FET input and low price.
They are very neutral sounding too. The ADA is a tube preamp, right? That means that the tube will do the coloring of the sound.
OPA2134 is a dual opamp - if you need a single opamp version go for the OPA134PA instead.
Best,
Peter |
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| MP2OLD |
Peter,
Thanks for your input on op amps. I will try the 2134 to see how sound changes. My feeling is that a fast slew rate may be best for digital signals, but maybe not for analog. Low noise and less coloration is my goal. |
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| jazzpeter65 |
If you need more coloration go for the OPA2604. It's almost tube-like. Very smooth but a little more noisy than the OP2134.
PS: If you need a quad opamp go for the OPA4134.
PSS: Are you making your own PCB for the ADA-clone?
Best,
Peter |
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| MP2OLD |
Peter, I am not "cloning" the pre-amp, just trying to "hot-rod" it with better parts. My level of skill is not in design, rather improvement.
Thanks again. I will let you know my results.
Phill:) |
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| jazzpeter65 |
Phill,
Hopefully you already know the site called: http://www.adadepot.com/
It's a dream come true. All the manuals & schematics for the whole ADA range to download. I have learned a lot from that site.
BTW: I'm designing my own guitarpreamp at the moment.
- Peter |
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| MP2OLD |
Peter,
I have used an ADA MP-1 since they first came out. I have seen many imitators come & go, but none compare to the quality & sound of an ADA. I gigged with mine for at least 10 years before semi-retiring. Now I use it for recording and playing in our church band. It is versatile enough to allow all kinds of sounds.
I have found the ADA Depot site and have downloaded the schematics I needed. I am now replacing the resistors in the MP-2 with Vishay/Dale 1% metal film, replacing diodes with MUR type & upgrading the capacitors. After I clean up the signal & power paths, I will experiment with op amps.
Keep me posted on the progress of your amp design. If I were to design a pre-amp, I would follow the ideas that made ADA such a cult classic.
Thanks for your interest.
Phill:cool: |
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| jazzpeter65 |
This is how my "Generic All Purpose Guitar Preamp" will look like when it is done.
Schematic will follow.
- Peter |
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| jazzpeter65 |
| ...and here is how it looks in "the real world". |
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| guitargully |
| so changing the OP amp in an amp will create a different sound? For example, if i wanted a different type of distortion i could swap the OP and get a different sound? OOO this sounds cool.. heck build an 8PXT switch (X being however many chips you throw in) and switch it for different sounds.. haha |
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| MrGuitardeath |
Generally switching op amps won't really change your distortion sound.
You may get an increase in treble, bass or mids, possiblly all three or only in one. One chip may simply sound smoother while another sounds harsher.
A couple other things that may happen is you might get a huge drop in gain or it may just be a moderate decrease.
The other is it may totally change your sustain. Several chips I used did this really bad. My sustain went from say 10 seconds to maybe 4 or 5.
The best duel op amp to use is from Texas Instruments. The Burr Brown OPA2604. It won't change your sound persay but it will improve it dramatically. It is very smooth and tube like sounding. It makes solid state sound warm or warmer than it already did. There is also a single op amp version the OPA604.
Most guitar amps use duel op amps.
So far in the guitar pedals I have built the 2604 overall sounds the best. The best sounding chips I have used are:
OPA2604 of course, the NTE858M which is a higher end replacement for the LF353 which also sounds quite good. Lastly would be the TLC072 which is probably the highest end chip that the big name companies use in their products.
Bottom line is in general the 2604 is the very best.
More expensive doesn't generally mean better. The NTE858 is like 3 dollars and some change. The 2604 is somewhere around a buck. These two chips sound a lot alike. The 858 is a little harsher and more defined in the bass and treble. The 2604 is smooth through all 3 bands. |
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| jazzpeter65 |
A comment to mister Checcks:
I generally agree with you about the OPA2604. One thing though; It's quite noisy compared to other opamps.
This is what I do about it: Looking through the schematic of a specific solid state amp, I deside where to place the OPA2604.
I generally place is where I have little gain in the circuit but wnat the coloring.
Where I have lot's of gain going on I place opamps like OP2134, OP37 or OPA627. These are quiter but doesent color as much as OPA2604. This way I get best of both worlds.
I'm about to try out the LT1115 for gainstage - one of the quitest opamps you can get.
It's noise is max. 1.2 nV at 1Khz where OPA2604 is about 10nV.
It's there some of you who have tried it out? |
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| MrGuitardeath |
All but one of the formentioned are single op amps and quite honestly I've never had any noise problems whatsoever from the 2604. Which is a duel op amp.........I've never heard of it coloring the sound drastically or any other op amp doing so for that matter. Really what it did for the sound in my applications was improve what was there.
Are you using it in tube circuits??
As far as most guitar related circuits go be it solid state amps or pedals...most use duel op amps not single.........:confused:
Anyhow I replaced 5 duel op amps in 120 watts RMS guitar head and the only place I had a noise problem was the reverb circuit. Easy solution here was to go back to the TLC072 the reverb originally used.
The amp used all TLC072's and the sound is just smoother and a bit richer now with the 2604's. More tube like. It's actually quieter now. In fact, the specs of the OPA2604 are very similar to a 12AX7 tube.
The only duel op amp you mentioned I have used the OPA2134 and man it was a wall of noise in those circuits.
I do know the circuit you use an op amp in has a lot to do with getting noise or feedback.
The general concensus on the internet is the OPA2604 is the best duel op amp for audio related circuits particularly guitar related ones.
I've got easily over 12 different types of chips to use in my guitar amp and pedals and hands down the OPA2604 has outperformed all others. Quieter, richer, warmer, gain is smoother and my tube emulation was slightly improved. There were just improvements all around. I've used a lot of different chips too I must say.
Maybe it's just the circuits I used the 2604 in but I'm inclined to believe otherwise based on my results and the postings of countless others that swear by it as well. Anyone out to capture a bit of the smoothness and richness of tube seems to swear by it.
I'm pretty surpirised by your noise comment more than anythingbut maybe I've just been lucky. The difference in sound I've noticed with using different op amps isn't usually too different or coloring. Generally I feel it's the same sound as before but with a slight change if any. One chip might be colder or warmer. One might be more grainy. ANother might cut sustain or gain maybe both.
I think the Duel op amp I liked most next to the 2604 was the NTE858M. Even with it's noise rating being 18 v, it was still quiet for me. These two chips sound VERY much alike but the NTE858M has a grainier and raspier sound when used in a gain circuit. It has a bit bolder treble and bass where as the 2604 is even in bass,mid and treble in comparison. Oh and this ones not cheap either. Most I've spent on a chip so far: $3.63 USD plus shipment of the entire order. OUCH! |
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| jazzpeter65 |
To MrCheecks: I guess that you have been lucky not hitting the noise floor of the OPA2604.
It's quite strange, but an 25 years old opamp - the NE5532 - has less noise.
OPA2604 has 10nV where NE5532 has 3.5nV. Quite a difference....
I think it's a matter of where you place your opamps in the circuit. Also a matter of how the circuit was put together. If it's a clever design you will have very little noise.
Problem is, most solid state guitar amps are not very well thought out. Not in hifi terms......;-)
I play alot of acoustic guitars (Godin) and I really like when my amp is dead quiet. I'm designing my own preamp at the moment for the some reason. |
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| MrGuitardeath |
I'm working on my own pre too. Mine will be solid state being I don't know enough about tube at this point and quite honestly I'd rather work with solid state.
I've heard SS sound as good as tube but certainly not always. I think it can be done easily through combining the right circuits more so than just designing a circuit from scratch. With the circuits I've built, mostly pedals, I realised from combining certain ones I could actually build my own amp that was as good if not better than the big name brand gear in the market.
I think I've got a really great design and now I'm studdying active filter controls built via op amps. I'll likely use a tone stack for starters though. I've got a killer transistor based tube emulation circuit and a few other tricks up my sleave for the pre. Best of all, the circuits are all really simple and noiseless. Even my gain circuit is noiseless.
I've been fortunate with my guitar amps. I own a SS Crate head and a cheap Rogue which is MusiciansFriend's house brand. The Crate uses a transistor based tube emulation circuit and also a mosfet power amp. It's a pretty dead on tube simulation but does not sound like any Specific tube amp. Very Fendery and Marshall like though.
The Rogue amp has managed a tube emulation via duel op amps and I'm not too sure of how. Then it also uses a mosfet so both amps power amp section clip like a tube does.
I used to play a lot of acoustic but being my acoustic broke and I couldn't afford a new one I've been without for quite a long time now and it's killing me. My old one I restored perfectly but then the clear coat dried all gritty for some reason. It's winter here so I'm unable to redo the finish.
Hopefully the new amp will sound good for my acoustic. I'll have a lot of clean gain for my clean channel and seperate EQ's for both. My power amp will be based on an opti mosfet kit from Seal electronics but I'm just buying the PCB. My tube emulation circuit will run through both channels which I've noticed many tube emulation amps only use emulation on the dirty channels. I find this rather foolish. |
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| jazzpeter65 |
What about your schematic? Could I see it?
I have allready my amp running as a prototype. Need to layout a PCB for it. |
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| jazzpeter65 |
| Preview of the schematic for my preamp... |
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| MrGuitardeath |
I'm pretty new at designing my own gear but I'd have no problem sharing the schematic once I have everything sorted out.
I'm basically combining some of my favorite individual cirtuits into a pre that I will later add an amp to. Next I'll build a head case or possibly a combo cabinet for it.
Looks like a really good pre you built there. If I'm right it looks like you have active op amp filters which I'm just recently really interested in. When I had spotted this pre on the other page I was assuming it was tuibe based. Tube is great but I've heard some solid state sound just as good.
I think as people such as ourselves continue working with solid state it will get better and better until even deticated tubeheads give in and start buying solid state. As is, the tube market gets smaller and smaller everyday but I still don't see a huge improvement in solid state. As of right now Crate, Tech 21, Randall and most recently Behringer make some really great solid state amps. As good as anything tube for that matter but Crate has drastically changed their cheaper line of gear by improving it and jacking the price up. Now they have a much higher end of SS amps that are really expensive for SS equipment. Really sucks cuz I liked them best.
Anyway out of curiosity have you ever worked with any tube emulation circuits? |
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| w00t |
| quote: | Originally posted by sangram
Really, you should swap out the opamps for a tube preamp stage, if you ask me.
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Hi there,
Is there a particular tube preamp you recommend? Thanks!
:D |
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| MrGuitardeath |
I think it's a bad idea to throw a tube in a solid state circuit that wasn't designed for a tube pre-amp stage. There's a good chance of feedback and microphonics being a major problem.
Most of all I'd like to know what brand, even model of amp you are modifying. Tubes are becoming more obsolete everyday. And quite honestly they don't sound any better than a SS amp granted you purchase the right ones. In fact, side by side I've heard SS tube emulation amps and tube amps sound IDENTICAL.
I've studied both subjects intensely and in blind taste tests guitarists can not tell the difference between tube amps and emulation amps. These studies were in fact done with the guitarists playing the amps blindly and having a variety of guitars to choose fro.
It's been my experience tube heads hate solid state for the simple fact it is solid state! I can see why someone would hate something when they spent $5000 USD on something that somone else achieved for $500 or $600. I feel it's a nostalgia and well no offense to tube guys but they are caught up with or simply stuck in the past.
I have PAiA 's tube pre-amp, the stack in a box, and side by side with my Emulation amp there is no difference. This pre is said to be THE best you can buy. It's response is no better or different than my Crate emulation amp. The microphonics of this pre are horrible on top of it not doing anything my amp doesn't already do and in fact does better.
I guess my point is tube is great but quite honestly it isn't all that. Flat out SS is a hundred times more versatile granted it's emulation.
Anyway good luck modding your solid state. Hopefully you won't ruin it! |
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| sangram |
Well, um to be honest the closest I've gotten to it is connecting a valve amp from an old radio to a solid-state output stage, and I'm actually working on a hybrid circuit from the ground up.
As far as not being able to tell solid-state and tube apart, I think depends to a large extent on what amps and whose ears we are talking about. Yes if the solid-state was designed to emulate a tube design it would be more difficult, but a good set of ears should be able to tell the difference some of the time.
Maybe time again for some double blind testing ?:D :devilr: I wouldn't mind some old Tweed amps and maybe a twin reverb, oh and let's throw in some JCM heads into the mix as well. :D you can send the equipment to me as gifts, I wouldn't have an issue with that ;)
But seriously, we are looking at valve buffered GCs so seriously. It cannot be too hard to design a hybrid circuit for guitar (except for the fact that we are dealing with low level signals as opposed to VBIGC/VBNIGC). Let me try and get started on it - my plate is really full as of now and I don't have a simulator, so I do my circuits the hard way - build them. |
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| MrGuitardeath |
I still Digress some amp models you would never know weren't tube, doesn't matter how good your ears our. Some amps yes, some amps a complete no.
Oh and I'll send you those amps right away.....hows the 3rd Sunday of this week sound???
:D |
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| sangram |
| 3rd Sunday of the week sounds good :D |
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| MrGuitardeath |
Boy the NE5532 made a huge difference when used in the signal boosting section of my amp circuit.
Talk about warm, fuzzy and dense !!!
My amps sound has improved ten fold. |
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| DragonMaster |
Anyone knows a 4-chan opamp better than a TL064(Talking about PSU noise and output noise)?
I'm upgrading a Kawai keyboard too : a K5(With this you can here how sounds a LM386(with 4 TL064 in series as preamp) with a noisy PSU, a enough loud white noise to turn you depressive if you hear it for too long, even when you play notes) |
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| DragonMaster |
| And now : for an LM386 ? (IMO I think it's a single channel powerful opamp) |
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| skyraider |
Ive tried 2132, 5332, 072, 4558 opamps.
I still prefer the coloured, muddy sound of jrc4558. For me, this is the closest to tubes. Even though it is noisier, but the tones im getting compensates for that. Anyone has tried this chip?
5332 is too 'SS' for me. Even the old faithful 072 sounds warmer than 5332.
Could not say Ive tried 2604 though.. |
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| rabstg |
Hi All-
I have read allot of comments saying one OPAMP is better than another and would like to build a circuit to experiment with.
May I ask which chips are pin compatible so I can build a test bed and then swap opamps? |
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| skyraider |
Basically, all the single opamp(741, 627, 604,5334), dual opamp(2132,2134,072,5332, 2604, 4558), quad opamp(074,..) are interchangeable. You have to check it yourself what type of opamp it is.
But sometimes just changing the opamps is not a good comparison, because some opamps has different operating conditions. You have to tweak the circuits as well. |
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| rabstg |
So if I'm buffering one channel why would I use a dual or quad opamp?
And in "normal" configuration are the dual opamps in parallel on a single channel? |
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| amz-fx |
Other than possibly noise floor, or the input impedance, all opamps will sound much the same in guitar use...
Why? The response of a typical guitar amp speaker drops drastically after about 4800 Hz. Differences or distortion in the upper octaves are filtered out!
Also, most people will have trouble discerning a 1% distortion in a circuit, much less the 0.001% differences that come from subbing different opamps into it. It's a fact...
Here's the frequency response of the classic Celestion V30:
Also, check out my 20 Commandments of FX Design: http://www.muzique.com/editor.htm#cmd
Your mileage may vary... :D :D
regards, Jack |
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| skyraider |
| quote: | So if I'm buffering one channel why would I use a dual or quad opamp?
And in "normal" configuration are the dual opamps in parallel on a single channel? |
What I understand is that you want to build a test bed to experiment with different opamp sounds? I dont think its a good idea, because the opamp might sound good in the testbed, but as a complete guitar circuit, it might sound bad. Why dont you just replace the opamp in your amp with a socket and try different opamps for comparison?
As a sidenote,
when i build my guitar preamp, I used TL072. It sounds ok, but I have the itch to try out better components. So I first tried out the NE5334 which has better performance than TL072. However, the NE5334 dont last more than 5 minutes in the circuit, and finally I settled for JRC4558. (NE5334 is much superior than JRC4558 in audio circuits)
| quote: | | Also, most people will have trouble discerning a 1% distortion in a circuit, much less the 0.001% differences that come from subbing different opamps into it. It's a fact... |
In guitar circuit, those measurement values has almost no meaning. Even 741 IC can sound good in certain effect pedals |
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| amz-fx |
| quote: | | Even 741 IC can sound good in certain effect pedals |
It certainly can but in those circuits it is probably acting as a defacto lowpass filter... you will get better performance by using a more modern chip (like a TL071) and tweaking the frequency response of the R-C components to your taste.
The distortion measurements certainly have meaning especially when micro-differences in components are being compared.
I did a test a few years ago where I made a TS-9 clone using cheap ceramic capacitors and another using all expensive metal film and polypropylene capacitors... in blind A/B tests, none of the guitarists who played the pedals could detect any difference between them.
http://www.muzique.com/editor.htm#caps
:) best regards, Jack |
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| skyraider |
Hi Jack,
Do you hear any major differences between TS-808 and TS-9? I have built the 808, and wondering if its worth the effort to build the TS-9.
What opamp do you use for your clone? From my tests, I found LM833 is the sweetest. (I couldnt get my hands on NOS JRC4558) |
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| rabstg |
| quote: | Originally posted by skyraider
What I understand is that you want to build a test bed to experiment with different opamp sounds? I dont think its a good idea, because the opamp might sound good in the testbed, but as a complete guitar circuit, it might sound bad. Why dont you just replace the opamp in your amp with a socket and try different opamps for comparison?
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Hi Skyraider-
Actually I need to build just a buffer circuit for a guitar and not replace an opamp in a device.
I am currently hoping to build the buffer around the BB OPA134 but since I need this buffer to be as transparent as possible I was going to build a test circuit to evaluate as many opamps as possible.
I need a gain of 1-2 but mostly need the impedance of the guitar pickup to be changed and be able to drive a LONG cord with low noise. |
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| amz-fx |
I don't hear any MAJOR differences between the TS9 and TS808... the reason I made the TS9 pedals was because I had an original TS9 to compare with... I used old RC4558 chips in the clones.
If you want a good buffer chip, try something like the OPA2604 which is high input Z and can drive long lines easily.
Or go hog-wild and get one of these chip replacements: http://www.lcaudio.dk/com/ad8065.htm
:D
regards, Jack |
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| rabstg |
Hey amz-fx-
So after looking at that I have to ask, are they paralleling two opamps?
Is there no decoupling resistors or anything?
Can you parallel two opamps like that with direct connections? |
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| skyraider |
You can try this buffer circuit, I took it from ampage website sometime before.
You dont need to parallel two opamps, there is nothing you can gain from doing it. If it is a dual opamp package, you can just ignore the other channel. |
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| amz-fx |
| quote: | | Can you parallel two opamps like that with direct connections? |
You can parallel two opamps.... what you get out of it is increased current drive. Typically, a small value resistor, 10 - 50 ohms is inserted on the output of each opamp before they are combined to the signal output. This insures that the opamps share the drive more equally.
regards, Jack |
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| rabstg |
Great!. That was what I was looking for regarding the parallel opamps..
I will try a single first, but then if needed go parallel.. |
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| skyraider |
Parallel opamps has no advantages to the buffer in this application. Sure you get more current, but it is unecessary. Furthermore, you increase the noise level which would be amplified few hundred times later in the amp.
Something worth tweaking, try biasing the opamp into class A. It has been done successfully with audio circuits, and I believe it could do some miracles for guitar buffer too. |
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| rabstg |
Well I grabbed a 741 OPAMP from radioshack to play with until the OPA627 arrives.
I did not see any method of biasing the opamp..
Any suggestions?
Can the OPA627 be biased class A?
What OPAMP would you recommend as a buffer biased class A?
And sorry for the questions, but does an opamp biased into calss A require a heat sink? I could glue on to the top of the package maybe... |
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| skyraider |
Try this link for more information:
http://www.diyaudio.com/forums/show...8984&highlight=
Basically you connect a resistor between the -ve supply to the opamp output. The preffered bias current is between 5-10mA. Lets say your -ve supply is -4.5volts, and you want to bias it to 10mA. Just use R=V/I, you get the resistor value of 450 ohms(470 preferred value)
It works sometimes with certain chips, but Ive not tried it with guitar buffers yet. |
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| amz-fx |
| quote: | | Parallel opamps has no advantages to the buffer in this application. Sure you get more current, but it is unecessary. Furthermore, you increase the noise level which would be amplified few hundred times later in the amp. |
Using a pair of opamps in parallel will actually decrease the noise by about 3dB due to random cancellations... four opamps in parallel would reduce it even further but that's about the practical limit.
I don't see any reason to try to force the opamp into class A operation since this cuts the available clean headroom in half... though it certainly is a point for experimentation. :)
rabstg, there are some practical examples of buffers on my site at:
http://www.muzique.com/lab/buffers.htm
regards, Jack |
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| rabstg |
Hey Jack-
Thanks for the info.
As the signature states, I'm from Lafayette.
I'm part of the economic displacement program we routinely run in LA.
Mind me asking what area you live in, and what bands your currently playing with? |
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| skyraider |
| quote: | | Using a pair of opamps in parallel will actually decrease the noise by about 3dB due to random cancellations... four opamps in parallel would reduce it even further but that's about the practical limit. |
I didnt know that
:eek: :confused: :eek:
But i never see this idea implemented in any circuits before.. I guess I can try it with my noisy JRC's |
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| skyraider |
A bit sidetrack,
Jack,
Im going to try one of your distortions some day. The shaka Bradah looks very appealing |
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| MrGuitardeath |
I just recently built a JFET buffer very similar to the ones on Jack's site.
Talk about no noise and a richer tone!!!!
I made some simple mods.....DOn't really know what I'm doing but they worked.
Here's the one I built:
http://www.till.com/articles/GuitarPreamp/
On the voltage bleed section, I used a 20 k trim pot which I keep wide open for optimum output.
I also eliminated the output cap and resistor, and swapped the 6.8k resistor with a 15 k.
The horrendous treble drop off is no longer an issue.
Dead silence and quite honestly it seems to be giving me a little extra sustain. Hate to say it but this circuit performed rather poorly untly I made those simple changes......don't even know exactly what some of them did other than the 20 k trimmer.
Is it possible to use this buffer POST high gain to clean up the sound??? |
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| amz-fx |
| quote: | | Is it possible to use this buffer POST high gain to clean up the sound??? |
Once you get noise or distortion in a signal it is quite hard to remove, so it isn't going to do that, but it might sound good in that position for other reasons.
| quote: | | The shaka Bradah looks very appealing |
It sounds like no other overdrive on the market; you should try it!
| quote: | | Mind me asking what area you live in, and what bands your currently playing with? |
I live in Baton Rouge, but am currently retired from playing live. I played in bands for many years but gave it up after I moved to Louisiana a few years ago.
Regards, Jack |
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| MrGuitardeath |
Yeah I noticed using the buffer post gain seemed to give me a richer or denser tone.
Seemed very tube like to me and it actually did reduce noise. |
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| Dermo |
AMZ - I love those quotes on that link you posted a while back.
In my experience, replacing op amps in new designs rarely does much to improve things. Most people use at least a TL072 or 5532 in commercial products and unless you are doing mic preamping, or really high impedance, low level stuff, the difference will be inaudable, especially when proper ABX testing is done.
That being said, I do tend to use OPA2134's instead of TL072s in our products if audio goes thru them. :eek:
When preamping a guitar, depending on the guitar, a TL072 may actually end up being quieter than a 5532 because of the current noise difference. High impedance guitars like strats and tele's and even Humbucker type guitars, have enough noise that you probably still wont notice a difference between any decent op amp. My point about the TL072 being quieter is due to the current noise being lower in it, and if you have a guitar with +100K output impedance, the current noise of a 5532 will make it noisier than a FET input OPAMP, even if the voltage noise is 6db or more worse. When I have plugged in a guitar to an identical preamp with normal volume settings, the buzz from the guitar was soooooooooooooo much louder than the opamp noise that I was cracking up.
The comment about the 4558's sounding more tubey was interesting. I think those old opamps work really well and the slew rate may be why they sound more tubey. They are very slow. If I remember, they clip squarely without inversion which is important. Guitar plucks can be 20dB above the rest of the tone, and very brief, so if you clip them quickly, you wont even hear it. Bell labs said any clipping below about 1mS (900uS) was inaudible and I believe them. In a heavy electric guitar, one must remember that freqs above 10K are often USELESS:whazzat: <ducking from the audiophile guitarists!> I have seen major mixdown engineers roll off all freqs above 8K on heavy guitars to tighten them up, make them less hissy, and leave that area for other instruments.
Holy Quacamole! I've run on and on. and now I must RUN ON!
CIAO!
PS. I just remembered, dont go tooo crazy over your coupling caps either. Ive actually only seen a few times where the cheapest cap performed audibly or measurably bad. Tube circuits require high voltage caps and that can be a different story. But I have people ask me all the time what caps to use and I say, What do you have laying around? :D When I can, I just eliminate caps completely in the audio path. THIS IS ONE PLACE A GREAT LOW OFFSET OPAMP CAN HELP OUT! |
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| DragonMaster |
Anyone knows an opamp that isn't much influenced by DC power line noise?
I've got a synth using TL064 opamps and there's a -58dB noise level. Headphones output use a LM386 and it's REALLY noisy. The noise seem to come from power line because when the synth is initializing, there is no noise even if the opamps are powered. Maybe there are mute transistors?
Someone used OPA4124s instead and told there was less noise, but I think he told there was still some.
Also, there are M5222L VCAs that seem pretty rare in it. No datasheets are available, but I found pinouts in a schematic I found somewhere. Thanks to google PDF search, the synth scheme pinout aren't descriptive. These VCAs seem noisy since someone that had these in a video cam bypassed them and used a separate volume control instead . . .
Can replacing the 7806 regulators by something else help? Rectifiers? |
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