Thinking about restoring a Crown SL-2 I have owned since new. It works, but the bass seems muddy. (might just be me)
Any suggestions on changing out the op amps?
I would think I should replace all the caps on the board, due to the age any way. Suggestions on upgrading them?
I am fair with a iron, and have a good adjustable temp iron. I have also built several kits, so I am good on the mechanics of it, but short on the theory.
Any help, suggestions would be greatly helpful!
Any suggestions on changing out the op amps?
I would think I should replace all the caps on the board, due to the age any way. Suggestions on upgrading them?
I am fair with a iron, and have a good adjustable temp iron. I have also built several kits, so I am good on the mechanics of it, but short on the theory.
Any help, suggestions would be greatly helpful!
Yes, there are lots of electrolytic coupling caps in this unit, so replacing them should be an easy upgrade.
If you are still unhappy after that, try bypassing some circuit blocks entirely, like the low filter block,
and the tone control block. Only after that should you try replacements for the 5532 op amps.
Ok, before I start replacing parts, maybe you can offer some suggestions on where to start.
I finally hooked everything up in my new apartment, and at first I thought the speakers were blown... Bass was slightly muddy, but sounded eh, low Midrange the same, mid highs to highs sounded like a cracked or separated speaker cone, kind of buzzy and shrill.
I figured it was just my Ipod, so I pulled a CD player out of storage, and it was the same, as a last resort, I hooked up my home theater processor and everything was good!
So the Crown SL-2 is definitely bad. Any suggestions? As I said before, I was planning on replacing the caps, but with what type?
Any other suggestions would be helpful!
I finally hooked everything up in my new apartment, and at first I thought the speakers were blown... Bass was slightly muddy, but sounded eh, low Midrange the same, mid highs to highs sounded like a cracked or separated speaker cone, kind of buzzy and shrill.
I figured it was just my Ipod, so I pulled a CD player out of storage, and it was the same, as a last resort, I hooked up my home theater processor and everything was good!
So the Crown SL-2 is definitely bad. Any suggestions? As I said before, I was planning on replacing the caps, but with what type?
Any other suggestions would be helpful!
Read your power supply voltages under load. any sag, you know which caps to replace first.
I find if I buy electrolytic caps over 3000 hours service life, they are premium in most other respects. Brands made outside the country of fake concrete schools and bridges, with the QA paperwork only tradition, have been Nichicon, Rubicon, Panasonic, Vishay Sprague. Others from the country of origin of 99% of all consumer products, that have worked okay so far in my hifi & organs, have been united chemicon and multicomp. I USA you are not allowed to know the country of origin of a product you buy until it has been shipped to your door.
Film caps and ceramic caps are not usual suspects of problems, unless an output transistor has failed and sent rail voltage banging through the driver and preamp areas through the base of the output transistor.
Bad solder joints and oxidized connectors are more problems than components, other than the speaker disconnect relay contacts. Cleaning the speaker relay contacts (if any) are sort of a first step on a 10 year old amp anway. Any disconnects in the signal path, like 1/4 phone plugs with the internal switch, are also candidates for the anti-oxigen patrol. No sandpaper or emory cloth, it leaves particles of insulating oxide embeded in the contact. Files or picks only.
Ribbon cables and any connector with a punch in contact to the wire, that needs to be removed and replaced after 10 years.
Unless you think a Crown is immune to a bad solder joint, I found one in a 98 Peavey product that every tech in there since then had missed. Since it made the output slam to positive rail frequently, there had been several such tech entries.
I find if I buy electrolytic caps over 3000 hours service life, they are premium in most other respects. Brands made outside the country of fake concrete schools and bridges, with the QA paperwork only tradition, have been Nichicon, Rubicon, Panasonic, Vishay Sprague. Others from the country of origin of 99% of all consumer products, that have worked okay so far in my hifi & organs, have been united chemicon and multicomp. I USA you are not allowed to know the country of origin of a product you buy until it has been shipped to your door.
Film caps and ceramic caps are not usual suspects of problems, unless an output transistor has failed and sent rail voltage banging through the driver and preamp areas through the base of the output transistor.
Bad solder joints and oxidized connectors are more problems than components, other than the speaker disconnect relay contacts. Cleaning the speaker relay contacts (if any) are sort of a first step on a 10 year old amp anway. Any disconnects in the signal path, like 1/4 phone plugs with the internal switch, are also candidates for the anti-oxigen patrol. No sandpaper or emory cloth, it leaves particles of insulating oxide embeded in the contact. Files or picks only.
Ribbon cables and any connector with a punch in contact to the wire, that needs to be removed and replaced after 10 years.
Unless you think a Crown is immune to a bad solder joint, I found one in a 98 Peavey product that every tech in there since then had missed. Since it made the output slam to positive rail frequently, there had been several such tech entries.
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You might want to replace the 3-leg regulators with the Super Regulators that Janneman redesigned for the DIYAUDIO store, or Peranders which have a smaller form factor. Unfortunately, the rails are a bit high to use the Linear Tech LT1963A. FWIW, I easily fit the original SR's into a much older IC-150.
If you're not uncomfortable with adapters, consider the OPA4134 to replace the TL074 in the phono sections. (Is a JFET opamp necessary here?)
Favorite electro coupling caps are Elna Silk or Nicchicon Muse, both available from DK.
If you're not uncomfortable with adapters, consider the OPA4134 to replace the TL074 in the phono sections. (Is a JFET opamp necessary here?)
Favorite electro coupling caps are Elna Silk or Nicchicon Muse, both available from DK.
Could you please let me know if these types of caps should be replaced?
I am already replacing all the can type, both radial and axial.
also the disc type since there are very few of them.
what about these 2 types that I have attached here?
In addition to these 2 types there is a third type that I do not have a picture of yet, looks like a silver tube?? Will try to get pictures tonight and post them tomorrow.
Thanks for your help
I am already replacing all the can type, both radial and axial.
also the disc type since there are very few of them.
what about these 2 types that I have attached here?
In addition to these 2 types there is a third type that I do not have a picture of yet, looks like a silver tube?? Will try to get pictures tonight and post them tomorrow.
Thanks for your help
Attachments
![20160116_153411[1].jpg](/community/data/attachments/498/498688-388efafd89d5f413e461d150dd83c7f1.jpg?hash=OI76_YnV9B)
![20160116_153454[1].jpg](/community/data/attachments/498/498707-37872746bad70ebde3d7ce869363c460.jpg?hash=N4cnRrrXDr)
DO NOT REPLACE THE 5532 OP AMPS, EXCEPT WITH THE EXACT SAME PART!!!
I can't believe how much lame advice I have seen thrown around on this and other forums about how to "upgrade" your op amps to make the sound "better". This is complete garbage in a large majority of the time. You cannot just replace one type of op-amp (with one kind of input topology) with another and expect the circuit to behave the same. On the contrary, jackinnj's advice to replace the TL072 with a modern FET op-amp is a good one as that would be an in-kind replacement with a much better modern part.
The 5532 is an EXCELLENT op amp for audio. It has low distortion, can drive VERY low impedance loads without falling apart, and is used in many, many pro recording consoles (with each console having tens of them). Unless there was some kind of electrical failure (e.g. short, etc.) the original op amps are likely just fine.
Your time is better spent replacing and and all electrolytic caps, especially in the power supply - these definitely age and will likely be very sub-spec. You do not need some esoteric cap, just a good quality new one. After the PS, look for any electrolytic coupling caps in the signal chain.
I can't believe how much lame advice I have seen thrown around on this and other forums about how to "upgrade" your op amps to make the sound "better". This is complete garbage in a large majority of the time. You cannot just replace one type of op-amp (with one kind of input topology) with another and expect the circuit to behave the same. On the contrary, jackinnj's advice to replace the TL072 with a modern FET op-amp is a good one as that would be an in-kind replacement with a much better modern part.
The 5532 is an EXCELLENT op amp for audio. It has low distortion, can drive VERY low impedance loads without falling apart, and is used in many, many pro recording consoles (with each console having tens of them). Unless there was some kind of electrical failure (e.g. short, etc.) the original op amps are likely just fine.
Your time is better spent replacing and and all electrolytic caps, especially in the power supply - these definitely age and will likely be very sub-spec. You do not need some esoteric cap, just a good quality new one. After the PS, look for any electrolytic coupling caps in the signal chain.
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Again, start by ONLY replacing the electrolytic caps. The ones you show above are NOT electrolytic caps. Elcaps typically have radial leads. Ceramic disc caps do not need to be replaced unless you can determine that one has failed.
C103 looks to be a TRW polycarbonate -- in the phono input stage. C5 is used across the a.c. line, the last one is a mylar that Jameco used to sell.
Looking at the schematic, you could replace the various 22uF non-polarized DC blocking caps with back-to-back ELNA silk, OR use the WIMA 22uF/63V PET cap. When this crown preamp was sold we didn't have caps that size in such small dimensions. If you have the space, you can use 22uF PP caps, but these are generally available only in high voltage. By now, 30 years later the NP electrolytics are well passed the date on the milk carton.
Looking at the schematic, you could replace the various 22uF non-polarized DC blocking caps with back-to-back ELNA silk, OR use the WIMA 22uF/63V PET cap. When this crown preamp was sold we didn't have caps that size in such small dimensions. If you have the space, you can use 22uF PP caps, but these are generally available only in high voltage. By now, 30 years later the NP electrolytics are well passed the date on the milk carton.
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This is just simulation, so take it fwiw...the 4.7uF input cap (C101) might need some help, same with the output decoupling caps C107, C108. I am beginning to suspect that the Crown folks may not have picked the correct input node at which to analyze the RIAA performance:
Attachments
Thanks for your suggestions.
I will start with just replacing the electrolytic caps, which I will order tonight.
jackinnj: Thanks for the suggestion, but I have no idea what that graph is actually showing, but it sounds like you do. The preamp actually sounded quite good when new, but I am willing to make changes to make it better!
What it sounds like is you are suggesting increasing the values of C101; C107 and C108? And this would flatten out the graph?
I will start with just replacing the electrolytic caps, which I will order tonight.
jackinnj: Thanks for the suggestion, but I have no idea what that graph is actually showing, but it sounds like you do. The preamp actually sounded quite good when new, but I am willing to make changes to make it better!
What it sounds like is you are suggesting increasing the values of C101; C107 and C108? And this would flatten out the graph?
I checked it again, I had an error in one of the nodes, so disregard the simulation. I thought that 4.7uF would be satisfactory.
In any event, you could replace the input coupling cap with a wima film cap. They are either 4.7u or 5uF 63V and available at Mouser.
In any event, you could replace the input coupling cap with a wima film cap. They are either 4.7u or 5uF 63V and available at Mouser.
The gain of the phono stage seems more than adequate for an MM cartridge at about 50dB (with R1_A/B set for minimum gain). you can adjust R1_A/B for another 20dB of gain for MC, or change the value of R109 from 340 to 32 Ohms. The latter, however, will change the response of the RIAA network. I think that the person who wrote in the R109 change didn't look at how it would affect the phono response.
If you're using an MC cartridge, then the values of R106,7 will be much , much lower, i.e. maybe 100 Ohms.
If you're using an MC cartridge, then the values of R106,7 will be much , much lower, i.e. maybe 100 Ohms.
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