MM Stingray 2 band shared pcb design

[remiiiiiii]

There are many op amps 'better' than the LM4250, which is a (once great) design from 60 years ago. But the thing is to find an op amp that is still available in the same DIP8 format as the LM4250. Last I checked a year ago there were at least 5 or 6 options. And of those the best are LT1097 and LT1012. Both are way quieter, slow but not nearly as slow as the LM4250, decent on power consumption and may be stocked in DIP8 form.

For the LT1097 it needs to have the CN8 suffix in the part #. I just got some, they were backordered for more than 6 months. Don't stall too long!
Link Removed

For the LT1012 look for the DN8 suffix, at Digikey but not Mouser at this time:
Invalid Link Removed

Others that will work. All will be quieter and faster than the original, but choose only if the above fall through:
TLE2061 This is the re-designed TL061. Specs say it is as noisy, LTspice model says it is quieter. Must have 'P' in the part# to be DIP8.
TL061 Ancient chip very good on battery life, some hate it for high frequency hiss, but in this preamp should be decent. And quieter that the LM4250, which most people don't complain about. Must have 'P' in the part# to be DIP8.
TLE2021 Quieter than the original, some noise in the bass region. You might say "I like it, it's really fat (or phat)." Must have 'P' in the part# to be DIP8, like CP or ACP suffix.
LT1637 Last resort but it should work, and like the TLE2021 noisy in the bottom end. CN8 or IN8 suffix.

Last comment--this is important--don't buy from the Amazxx or eBxx sites since they may well be counterfeit. I'd be suspicious of any other source than a real electronics supplier (like Mouser, Digikey, Allied Electronics, Element14, Avnet) that orders directly from the manufacturer. In the case of the above xxx dealers these kinds of parts come from independent vendors and the web site has no control over the validity.

Very interesting post.
So in your opinion, what is the best alternative to the LM4250? The LT1097?

Thanks

 

[BQFS]

Very interesting post.
So in your opinion, what is the best alternative to the LM4250? The LT1097?
Thanks

I just ordered a bunch of NJM4250D
NISSHINBO MICRO DEVICES INC

OP Amp Single GP ±18V 8-Pin PDIP ... Item Price: $0.667
Quantity: 50

from Online Components

Can't beat the price. They are reliable, pretty much a dead copy of the original LM4250 ICs. You have to buy 50 at a time, and I only intend to build about a dozen more 2-band MM clone preamps but I was buying ICs that were $6.50 each, so it still works out to be cheaper. Plus the 4250's current draw is WAY less so the battery life will approximate the shelf life, up to 5 years or so, assuming you buy good 9v batteries.

 

[Gaano124]

I just ordered a bunch of NJM4250D
NISSHINBO MICRO DEVICES INC

OP Amp Single GP ±18V 8-Pin PDIP ... Item Price: $0.667
Quantity: 50

from Online Components

Can't beat the price. They are reliable, pretty much a dead copy of the original LM4250 ICs. You have to buy 50 at a time, and I only intend to build about a dozen more 2-band MM clone preamps but I was buying ICs that were $6.50 each, so it still works out to be cheaper. Plus the 4250's current draw is WAY less so the battery life will approximate the shelf life, up to 5 years or so, assuming you buy good 9v batteries.

Buy a LM4250CN Copy at AliExpress, they're like 3$ per stock, 10 pieces each

 

[Edulpn]

Seems like the Mouser cart also has a couple of electrolytic capacitors that are also marked as obsolete:

• UMA1H010MDD
  
• UMF1C100MDD

Anything specific I should keep in mind sourcing these?

 

[Passinwind]

Seems like the Mouser cart also has a couple of electrolytic capacitors that are also marked as obsolete:

• UMA1H010MDD
  
• UMF1C100MDD

Anything specific I should keep in mind sourcing these?

The physical footprint (diameter, lead spacing, and then maybe height) is by far the most important thing in this case. 5mm tall caps are going missing in droves right now, but 7mm tall ones do just as well in many applications, luckily.

 

[BQFS]

Buy a LM4250CN Copy at AliExpress, they're like 3$ per stock, 10 pieces each

Unless you have personal experience to the contrary, I would be wary of any ICs labeled LM4250. That's a trademarked designation, which probably means someone bought a generic single amp IC and put their own designation on it. I, personally, would not trust any IC that isn't sourced from a reputable authorized reseller or wholesaler like Mouser or Digikey or Online Components. AliExpress would make me more wary than even eBay as a quality source. I paid just a bit over $30 for the 50 I bought from Online Components. They work great.

I don't know about anyone else, but $30 for 50 from Online Components, a highly reputable source, seems a much better (and safer) bet than paying AliExpress $30 for 10 where you have NO idea who the actual source is.

Just my 2 cents (based on two electronics degrees and 40+ years of bench tech experience).

 

[Edulpn]

The physical footprint (diameter, lead spacing, and then maybe height) is by far the most important thing in this case. 5mm tall caps are going missing in droves right now, but 7mm tall ones do just as well in many applications, luckily.

Ah, nice, thanks! Are electrolytics a must or other types of the same spec could work?

 

[BQFS]

I have not experimented with the basic design, but so long as the value is the same, the type of cap should not matter that much. I do get a kick out of those folks who think that the Sprague Orange Drop 0.047uf cap is the "tone capacitor" that makes a P Bass sound like a P Bass. As if the passive tone circuitry has intelligence to know what type of cap is in the circuit, let alone who made it. I try to balance my choice of components based o the highest quality part I can obtain for the lowest price.

 

[Edulpn]

I have not experimented with the basic design, but so long as the value is the same, the type of cap should not matter that much. I do get a kick out of those folks who think that the Sprague Orange Drop 0.047uf cap is the "tone capacitor" that makes a P Bass sound like a P Bass. As if the passive tone circuitry has intelligence to know what type of cap is in the circuit, let alone who made it. I try to balance my choice of components based o the highest quality part I can obtain for the lowest price.

Yep, I have a good laugh everytime I see those "premium premade electronic harnesses" for $300 with soviet made oil caps and unicorn hair braided wire...

My local electronics store seems to carry Nichicon "FG series audio grade capacitors", 5 pieces for $10 (CAD) a pop... Probably too expensive for what they are, but still cheaper than getting something shipped if I can't find an alternative at Mouser/Digikey.

 

[Passinwind]

Ah, nice, thanks! Are electrolytics a must or other types of the same spec could work?

Aluminum electrolytics are likely to be the cheapest and easiest solution, when I can get to my PC a little later I’ll post a few sub part numbers for you. Panasonic GA series is one of the usual suspects, for starters. Anything costing over 50 cents a pop or so is probably overpriced IMO.

 

[Edulpn]

Aluminum electrolytics are likely to be the cheapest and easiest solution, when I can get to my PC a little later I’ll post a few sub part numbers for you. Panasonic GA series is one of the usual suspects, for starters. Anything costing over 50 cents a pop or so is probably overpriced IMO.

I was able to find two Panasonic 10uF caps:

• EEA-FC1E100
• EEA-GA1C100 (based on your recommendation)

For the 1uF, I found a couple of others from brands I'm not familiar with: KEMET, Illinois Capacitor and Rubycon.

 

[Passinwind]

I was able to find two Panasonic 10uF caps:

• EEA-FC1E100
• EEA-GA1C100 (based on your recommendation)

For the 1uF, I found a couple of others from brands I'm not familiar with: KEMET, Illinois Capacitor and Rubycon.

All of those brands are fine. I was using Rubycons in my onboard designs until very recently, when they discontinued the 5mm tall ones in the values I typically need.

 

[Passinwind]

Personally, I'd stick with the same brand and series for both parts, so probably:

1uF: Link Removed

10uF: Link Removed

I tested this series in some DIY onboard builds a few years ago and they worked just fine. Kemet film caps are my default choice in many circuits, it's definitely a very reputable brand.

 

[ReidK]

Hi folks. I've read most of the threads about this preamp, and I have a couple of questions.

1 Was there ever a consensus reached about whether the feedback resistor in the bass loop should be 100k or 220k? I see that it's called out as 100k on these boards.

2 I saw a frequency response plot somewhere that illustrated the difference in bass response between the 1uf output cap and the 10uf. I didn't save or bookmark it. Can someone please point me to it? IIRC the curves were nearly identical above 30 hz, and it looked like the 1uf would help eliminate subsonics, essentially acting as an HPF.

Thanks, and thank you very much mnats!

Reid

EDIT: Never mind #2, I found it:
https://www.talkbass.com/posts/17555779/

Thanks for posting that, PW.

Reid

 

[Passinwind]

Hi folks. I've read most of the threads about this preamp, and I have a couple of questions.

1 Was there ever a consensus reached about whether the feedback resistor in the bass loop should be 100k or 220k? I see that it's called out as 100k on these boards.

2 I saw a frequency response plot somewhere that illustrated the difference in bass response between the 1uf output cap and the 10uf. I didn't save or bookmark it. Can someone please point me to it? IIRC the curves were nearly identical above 30 hz, and it looked like the 1uf would help eliminate subsonics, essentially acting as an HPF.

Thanks, and thank you very much mnats!

Reid

EDIT: Never mind #2, I found it:
https://www.talkbass.com/posts/17555779/

Thanks for posting that, PW.

Reid

For my builds I ended up liking 180K for that resistor, FWIW. But I never put one in an actual Stingray.

 

[ReidK]

For my builds I ended up liking 180K for that resistor

"None of the above" has always been my favorite answer.

But I never put one in an actual Stingray.

I won't be, either!

Thanks again.

 

[ReidK]

Apart from the bias supply, there's no supply filtering. Is it assumed that there's an outboard cap, or does it just not use one?

Or is the first cap shown on the bias supply enough for the main supply as well?

Sorry if this is an old faq for this circuit!

 

[Edulpn]

OSHPark took it's sweet time to deliver my PCBs, but finally put the circuit together and wired it up on my Sterling Ray4.
I have volume and Bass control, but seems like no Treble.
Any ideas on how to troubleshoot this? Measured the treble pot with my multimeter (both on the lugs and on the board solder points) and it seems to be working fine.
I'm using the 25K pot for volume, 1M For treble and 100K for bass (which I believe was the values in the stock wiring for my bass). Am I doing anything something wrong here?

 

[Edulpn]

Oh wait, went through a couple of the solder joints with the hot iron and flowed them a bit and seems like I have treble now!

 

[Gaano124]

Oh wait, went through a couple of the solder joints with the hot iron and flowed them a bit and seems like I have treble now!

Also you have to use C1M, not 1M with reverse wiring. Frequency response is different