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TL Audio EQ-1 Help Needed Replacing Pots And IC Chips
Old 1st March 2014
  #1
Here for the gear
 
Boombox Studio's Avatar
 
🎧 5 years
Talking TL Audio EQ-1 Help Needed Replacing Pots And IC Chips

hello all

im a newbie when it comes to upgrading and doing mods to audio gear myself

need some advice quite badly please

my tl audio eq-1 which has lived on my drums for past 15 years has given up as the pots are cutting out

from what i gather the x2 channel volume / gain pots are Dual 5KA centre detent with reverse law

then i need x8 100k centre detent pots for the volume / gain on the frequency bands

the shaft length are about 20mm

these pots seem impossible to find ? , tl audio do not stock them and the only place i managed to track them down wants a near hefty Β£100 for the original stock parts and the quality is pretty shockingly bad , these original tl audio stock pots start crackling after 2 or 3 years as i had more than one set over time

here is a picture of the original dual pot taken out , any ideas of replacements will be forever in my gratitude

see attachments for picture

last of all some advice on op amps would be fantastic

all the old op amps have been taken out and replaced with sockets as this unit had been on near everyday for 15 years

this unit had x7 ne5532 and x2 2017

from what i understand the 2017 sounds dirty and should be replaced , by 2019s ??? , please correct me if I'm wrong

also the x7 original ne5532 would you replace them for new ne 5532s ? or try something like the lm 4562 or LME49720NA or the more expensive LME49720HA ?

I'm sure a few of you will be thinking caps , they all been replaced with decent panasonics , not looked at resistors but the ones inside are all operating correctly

thank you for your help and time

best regards boombox
Attached Thumbnails
TL Audio EQ-1 Help Needed Replacing Pots And IC Chips-dual-5k-potentiometer-centre-detent.jpg  
Old 1st March 2014
  #2
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mjrippe's Avatar
 
🎧 10 years
Have you tried cleaning the pots?

"all the old op amps have been taken out and replaced with sockets as this unit had been on near everyday for 15 years"

They were still working, right? Leave them alone and they will be fine for another 15 years.
Old 1st March 2014
  #3
Here for the gear
 
Boombox Studio's Avatar
 
🎧 5 years
thanks for the reply friend

yes i tried cleaning the pots

a couple of days later i had 1 channel cutting out again

think they are really gone

i don't think you read my post correctly , all the op amps been taken out and now have sockets
Old 1st March 2014
  #4
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mjrippe's Avatar
 
🎧 10 years
Ok, I understand that there are sockets, but why were they taken out? Are the same opamps put back in? It seems like you want to replace them with new ones even though there is no problem with the old ones.
Old 2nd March 2014
  #5
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Richard Crowley's Avatar
 
🎧 10 years
I don't hold much hope for finding exact (or even mechanically equivalent) replacement pots.
Unless you either have extraordinary luck in finding some NOS somewhere, or have a big budget for having premium custom parts assembled for you.

A few decades ago, I wondered how digital signal processing and control would ever overtake traditional electro-mechanical designs.
Now, I wonder how long traditional electro-mechanical can last in the face of digital's many advantages. (Cheaper, easier, faster, more reliable...........)
Your dilemma is a prime indicator of the problem. You could even replace the pots with digital pots and make a new digital user interface.
Old 2nd March 2014
  #6
Here for the gear
 
Boombox Studio's Avatar
 
🎧 5 years
i will keep hunting for the pots which I'm sure will be fun

or try again to repair the old ones possibly

as far as the op amps go i was under the impression they have different charitoristics , headroom ect , some smooth some harder high end

i was also under the impression op amps did not last a lifetime and that 10 or 15 years was realistic time to change them

after changing caps , valves , pots and , op amps I'm hoping to bring this back to its original or better glory

as it does not sound anything like it did at new , level sounds down and started to sound almost low fi

reading reports people say the ssm 2019 is a better replacement than the original ssm 2017 as the 2019 has a smooth sound

just wanted to get some feedback about what to change the op amps to now

as I'm sure there are better suited op amps for each stage

sure i will make a couple of mistakes along the way thats why I'm asking for advice now

thanks again
Old 2nd March 2014 | Show parent
  #7
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Richard Crowley's Avatar
 
🎧 10 years
Quote:
Originally Posted by Boombox Studio ➑️
i was also under the impression op amps did not last a lifetime and that 10 or 15 years was realistic time to change them
That sounds extremely dubious to me. I would like to see some evidence of that.
Now, to be sure, in 10 or 15 year's time 2 or 3 generations of linear integrated circuit manufacturing technology and component design will have transpired, so there may very well may be NEWER chips that could be substituted. But I VERY MUCH doubt that the original chips themselves have any significant degradation mechanism at play.
Old 2nd March 2014
  #8
Here for the gear
 
Boombox Studio's Avatar
 
🎧 5 years
sadly I'm well beyond this stage now

thats why I'm requesting replacement op amp info

after reading other gearslutz posts I'm not the only person who has changed there op amps on tl audio products as there a fair few posts on this subject which all vary between a few brands

next time i will keep your valuable feedback in mind and be less fast to pull the trigger

its all a good learning process for me

you can make a mistake once but not twice thats for sure

also i will be interested to see how much difference caps and op amps make before we drop in the new tubes

i will report for others to read once we are all done and make my own report for other tl audio users
Old 2nd March 2014 | Show parent
  #9
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Richard Crowley's Avatar
 
🎧 10 years
Quote:
Originally Posted by Boombox Studio ➑️
after reading other gearslutz posts I'm not the only person who has changed there op amps
To be sure "op-amp rolling" is nearly qualified as an Olympic sport. But it is typically practiced in search of better performance, not because of deterioration of the original part operation.

Not everyone believes in the sport as popularly practiced: Op Amps: Myths & Factsl.
I rather agree with NwAvGuy.
Old 2nd March 2014
  #10
Here for the gear
 
Boombox Studio's Avatar
 
🎧 5 years
that was a very interesting read on nwavguy's blog , thanks richard

i might well just put the drop in replacement ic chips same as where originally in the unit at the end of the day

but i will do a test with some of whats called 'the exotic' chips and listen out for anything in the frequency range which sounds odd or nice

if there anything nasty going on i will be able to tell , will also run all the service manual checks

appreciate the feedback

cheers boom box
Old 5th March 2014
  #11
Gear Addict
 
Time Tech's Avatar
 
🎧 10 years
I'm rebuilding a eq-1 now. I took out all the pots and selector switches, ultra sonically cleaned and re lubed them. I've upgraded the PSU, and will start on op amp and tube rolling next. The advantage of this being a 2 channel unit, you can roll and upgrade one side and then A/B it with the "stock" side. Best of luck with it!
Old 22nd April 2015 | Show parent
  #12
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analogsynth's Avatar
 
1 Review written
🎧 5 years
Quote:
Originally Posted by Time Tech ➑️
I'm rebuilding a eq-1 now. I took out all the pots and selector switches, ultra sonically cleaned and re lubed them. I've upgraded the PSU, and will start on op amp and tube rolling next. The advantage of this being a 2 channel unit, you can roll and upgrade one side and then A/B it with the "stock" side. Best of luck with it!
I know it's a long time ago you posted this, but it would be really interesting if you posted the results for us, especially for me as I also have a TL Audio EQ1 that I'm thinking about upgrading as the Chinese made "National" branded tubes mine came with are not the best in the world.

I'm considering replacing them all with some new JJ low gain tubes since I can't really afford any NOS tubes as the prices they go for is out of this world. From what I understand, JJ tubes are the best bang for your buck and miles better than $2 Chinese rebranded tubes, which National supposedly is.

What about the op amps? I'm afraid I don't know anything about op amps and if they're not socketed I think I'll leave mine where they are.
Old 22nd April 2015
  #13
Lives for gear
 
🎧 15 years
Hi
ALL valves gradually deteriorate over the years, they are a 'consumable' item. As an observation some of the cheap 'chinese' valves, if used hard (which they are not really in these units) tend to 'fail' earlier than some other manufacturers. This is usually manifest as a loss of gain, although whether this reflects directly on this unit is harder to predict as the effect is not directly correlated.
The op amps are pretty much OK and don't 'need' changing. The mic amp chip, I believe SSM2017 has been superseded by SSM2019 which 'might' be better but again if that translates to a significant improvement for the whole unit is debatable.
If cleaning pots, they MUST be relubricated with the right lubricant as a dry 'track' will wear very quickly.
Matt S
Old 23rd April 2015
  #14
Gear Guru
I rebuilt a few of those. The EQ caps are 5mm mylar, stacked against each other with 3mm thickness. Tought to fit WIMA FKP's in there, MKP's at lower voltages will fit.

I would try LME opamps in there. Add a pair of .1 uf psu bypass caps from the power pins to ground. Check outputs on a scope to ensure stability. Check DC offsets, if below 5 mv, you can yank out or short out the el cap that follows.

The 1989 SSM2017 is long in the tooth. The Burrbrown INA217 and THAT 1510 are pin compatable substitutes as is the SSM2019. Also available with superior specs and sound is the Audio Upgrades PIP mic preamp module, designed to retrofit 2017 mic chip preamp layouts.

Soundcraft uses a 5k reverse log dual Alps pot for the mic/line gain on Delta, 6000, Venue and other models. there is no detent, but they would work.
Old 23rd April 2015
  #15
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analogsynth's Avatar
 
1 Review written
🎧 5 years
Thanks both for your input,

but what I really wondered is if a different brand of valve would make it sound smoother or better in any way. The JJ valves would surely be an upgrade, but I don't know how much that would affect the sound since this is not a guitar amp where overdrive characteristics is the all important issue.

I'm also wondering if it is possible to substitute the 12AX7 valves with 12AT7 or 12AU7 valves for a lower gain and more headroom, just like you would do in a guitar amp, or if this would mess up the workings of the unit.
Old 23rd April 2015
  #16
Lives for gear
 
🎧 15 years
Hi
The 'headroom' of the valves is WAY above the rest of the circuit. Direct substitution of alternative valve types as mentioned will not 'damage' anything but the bias conditions are different so the valves will be using a different part of their 'range'. The biassing is usually 'designed' so you get the greatest signal level capability for the least distortion. Other valves should have the cathode resistors changed to suit the different characteristics of the valve. Whether this is a worthwhile activity would have to be tried.
Matt S
Old 23rd April 2015
  #17
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analogsynth's Avatar
 
1 Review written
🎧 5 years
OK, that's as I expected, maybe not so wise to swap for a different type of valve, but the unit is known to not have the best of headrooms and valve distortion quickly sets in, for some that's the attraction (no need for enhancers to get that bright top end), but I want to temper it a bit and as the JJ valves are known for quite a clean sound I was going to take a chance on them, but if anyone has experimented with different valve brands and found a match that sounds sweet, I could maybe save myself some dough.
Old 5th May 2015
  #18
Lives for gear
 
gyraf's Avatar
 
🎧 15 years
An available pot that may be usable is the Monacor VRB-101S100, part-Nr.: 012430

2x100K Lin, center-detent.

It has splined shaft, but you may be able to mount your knobs anyway.

---

Please note, that pots getting scratchy nearly always is caused by leaky electrolytic coupling capacitors. Try recapping and clean pots again - it may work this time.

---


Jakob E.
Old 7th May 2015
  #19
Gear Nut
 
🎧 5 years
One thing to keep in mind is that scratchy pots can be caused by leaky electrolytic coupling caps that allow DC to travel through the pot. Before replacing the pots, I'd check the electrolytics. These could easily degrade over 15 years of being 'on' in a rack.

Sorry to be redundant - just saw the previous post!

Last edited by Monte McGuire; 7th May 2015 at 08:21 PM.. Reason: (didn't read previous post - sorry!)
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