Recommended caps for Carver C-1 re-cap

Fongolio

I have ordered free samples from National Semiconducter of the LM4562. I ordered 5 because that's the most you can for free and I just pay shipping. A very inexpensive way to test those op amps. I'm aware of the non standard pin out and think I'm going with either the Brown Dog adapter or most likely the JLM Audio adapter. The JLM is more money but it uses a dip socket for easy op amp swapping. Probably will go Nichicon and Panny's for caps. One question for FTGV though...do you think I would gain much by swapping both IC6 and IC7? They both appear to be in the output signal path. Bear in mind that I'm not an electronic whiz and am fairly new at reading schematics but am very comfortable with a soldering iron. Also which specific caps do you think I could eliminate after the new op amps are added? Thanks a bunch for your patience with me on this.

Kelvin

FTGV

Fongolio wrote: »

I have ordered free samples from National Semiconducter of the LM4562. I ordered 5 because that's the most you can for free and I just pay shipping. very inexpensive way to test those op amps.

Can't beat that deal.

. The JLM is more money but it uses a dip socket for easy op amp swapping.

Thats why I linked to it,as it will greatly simplify the mod.Playing with SMD parts is not always fun.:)

..do you think I would gain much by swapping both IC6 and IC7? They both appear to be in the output signal path.

All 4 segments of IC6 are in the phono preamp sections.If you are using the phono circuit then upgrading to the 4562's should provide a significant reduction in noise floor and increase in detail retrieval from vinyl.Two sections of IC 8 are in the tone control circuit so if you use the controls you may want to change it as well.IC 7 is the main line stage amp and also the infrasonic (rumble)filter for use with the phono section.

Also which specific caps do you think I could eliminate after the new op amps are added?

You certainly should be able to eliminate the main output caps C217 and 317.A check with a DMM after the mod should be done to be sure DC offset is very low.

Thanks a bunch for your patience with me on this.

Your welcome.There are a few other things that could be done but I will leave that for a later post.

Fongolio

The free LM4562's arrived today. Now I just need to buy a few more and send for the adapters. Four adapters for $100 but I'm thinking this upgrade to the C-1 with caps and op amps will be a very significant step up in sonic improvement.

FTGV

3 adaptors and 6 x 4562's will be enough to cover the phono,tone control and main line amp circuits.Also there doesn't appear to be any local power supply decoupling but I highly recommend adding some.This because the 4562 is a much wider bandwidth device than the stock opamp's so the addition of some decoupling at the power pins of the adaptors(pins 7,11)should reduce the likelihood of oscilation.At minimum use a .1 uf film,but preferably in combination with about 100uf of quality low impedance electrolytic.

FTGV

So any progress?

lanchile

if you are looking for good caps, just get Mundorf caps. I always use them in my diy amps. . for power supply get the Audio grade they cost around $25 each 10,000uf 63v. you can get them at Partsconexion.com

Fongolio

I'm waiting for the adapters. I've got 10 LM4562 op amps (5 free samples for me and 5 free samples for my son). One question for FTGV....the decoupling caps at pins 7 and 11...series? parallel? I know my newness to this is showing but I'm learning. After the op amps are done I will be doing the caps. Still undecided on what brand but the Nichicon and Elna's are the front runners and Panasonic's for the power supply. The Mundorf's are nice but VERY expensive. Mind you the Panny's aren't cheap either.

FTGV

Fongolio wrote: »

...the decoupling caps at pins 7 and 11...series? parallel?

If just using a .1uf film one lead goes to pin 7 or 11(one needed for each) the other lead connects to ground.If you add the electrolytic also it should be in parallel with the film.Since the 'lytic' is polarized attention needs to be paid to the direction in which it is installed.

Fongolio

FTGV wrote: »

If just using a .1uf film one lead goes to pin 7 or 11(one needed for each) the other lead connects to ground.If you add the elecrolytic also it should be in parallel with the film.Since the 'lytic' is polarized attention needs to be paid to the direction in which it is installed.

This is what I thought. The adapters are somewhere between Australia and here. I'm really looking forward to hearing the difference this mod will make. Thanks for all your help FTGV.

FTGV

I should point out that if you intend to use the 'lytics' with the films for decoupling the one connected to pin 7 needs to be reverse polarized.(negative lead connected to pin 7 other lead to ground).This because pin 7 recieves negative 12 volts DC.(Pin 11 recieves positive 12 VDC.)

Fongolio wrote: »

I'm really looking forward to hearing the difference this mod will make. Thanks for all your help FTGV.

Good luck and I look forward to your impressions aswell,and your welcome.

Fongolio

I just thought of something. You must be referring to pins 7 and 11 on the adapter as the new LM4562's are only 8 pins each. And thank you for pointing out the negative voltage on pin 7.

Kelvin

FTGV

Fongolio wrote: »

I just thought of something. You must be referring to pins 7 and 11 on the adapter...

Correct.

Fongolio

Just received the adapters today and there is a little film cap soldered onto the adapter board to what would be the old pin 8. Any ideas what this might be for FTGV? Anyway the project starts this weekend!

FTGV

Fongolio wrote: »

... is a little film cap soldered onto the adapter board to what would be the old pin 8. Any ideas what this might be for ?

It's connected to what would be pin 8 of one of the 4562's?What is the other end connected to?

Fongolio

Looks like a trace that runs to pins 8 and 14

Fongolio

Sorry I had that wrong. One end of the cap is to pin 14 and the other runs down a trace to pins 4 and 7.

FTGV

Strange,what actual pin's on the LM4562's will it be connected to when they are inserted into the the adaptor?

megasat16

I think the adapter has copper traces very close or crossing some traces in small area of doubled layered board? I may be wrong but It may be for parasitic oscillation.

Pics Please!

FTGV

Good thought James that might be it.I'd want to know what pins it connected to on the 4562's though,it may cause problems.

megasat16

Fred, I might be wrong. I am just throwing in what I knew. I am a little puzzled since the cap is wired to 2 pins on one end and 1 on the other end. I also don't know the pinouts of the adapter so I don't know how it will relate to the actual LM4562 pin assignment.

Fongolio

I've sent JLM an email inquiry about the purpose of the capacitor. There was no capacitor in the photos of the adapter on their web site.

I have to again correct what I wrote above the cap ties the two pin 4's together on the 4562's. On the other side it connects the two pin 8's on the 4562's together. Pin 4 on the 4562 is V- and pin 8 is V+ so what effect does the cap have on these?

Here's what I can make out on the adapter to 4562 configuration:
pin 1 4136 to pin 2 first 4562
pin 2 4136 to pin 1 first 4562
pin 3 4136 to pin 3 first 4562
pin 4 4136 to pin 4 first 4562 and to one side of the capacitor
pin 5 4136 to pin 3 2nd 4562
pin 6 4136 to pin 1 2nd 4562
pin 7 4136 unused
pin 8 4136 to pin 6 2nd 4562
pin 9 4136 to pin 7 2nd 4562
pin 10 4136 to pin 5 2nd 4562
pin 11 4136 to pin 5 1st 4562
pin 12 4136 to pin 7 1st 4562
pin 13 4136 to pin 6 1st 4562
pin 14 4136 to pin 8 2nd 4562 and to one side of cap

maybe this can help.

Kelvin

Fongolio

Forget all that was written above. adapter upside down. Someone check me for drugs please!! I am sooooooo feeble minded some days. Sorry.

Fongolio

Here is the ACTUAL pin placement:

pin 1 4136 to pin 2 first 4562
pin 2 4136 to pin 3 first 4562
pin 3 4136 to pin 1 first 4562
pin 4 4136 to pin 1 second 4562
pin 5 4136 to pin 3 second 4562
pin 6 4136 to pin 2 second 4562
pin 7 4136 to pin 4 first 4562
pin 8 4136 to pin 6 second 4562
pin 9 4136 to pin 5 second 4562
pin 10 4136 to pin 7 second 4562
pin 11 4136 to pin 8 second 4562
pin 12 4136 to pin 7 first 4562
pin 13 4136 to pin 5 first 4562
pin 14 4136 to pin 6 first 4562
The cap goes from pin 4 of the second 4562 to pin 4 of the first 4562. The other side goes to pin 1 second 4562 and to pin 1 first 4562.

I am near certain this is the correct placement and it checks out on the two chip diagrams. I'm still not sure what the cap is for though.

Fongolio

Below is the response from JLM Audio to my query about the purpose of the cap on the 4136 adapter:

HI Kelvin
The 0.1 mono caps is a extra power supply decoupling cap close to the opamp power pins to help keep modern dual opamps from oscillating due to long PCB tracks etc. So you should leave it as it will help with the LM4562.

FTGV

OK good the cap is on the power pins.They are correct and as I mentioned in post #35 the wider bandwidth of the 4562 could pose a problem with oscillation so adding some decoupling would be a good idea.

Fongolio

New op amps in!! Had a tiny problem with right channel not playing but traced it to an incomplete solder on one pin. Initial impression is first off higher gain on my mc stage. Less volume required for same db output. Next was like a veil had been lifted. As many of you know I use an eq (ADC Soundshaper 3 Paraequalizer) and I need considerably less eq for the desired bass and treble. Very clear and airy. Bass is better defined and hits with more impact. Treble is extremely articulate now but not etched. The mids have really come to life. I still need to do the caps so this is an excellent result so far.

Question: Do op-amps need a burn in time to sound their best?

Anyway, I can say this upgrade is well worth the effort and money. By the way I replaced IC's 6,7, and 8 so the cost was three adapters at $25 each plus shipping and the cost of shipping on the LM4562's since I got them on the sample program from National Semiconductor. So the cost is around $100 and now my C1 sounds even better than before. I am a happy dude!! Thanks everyone but especially Fred for your guidance in this project. Next up caps.

Kelvin

FTGV

Excellent stuff Kelvin

Fongolio wrote: »

Less volume required for same db output.

Hummm,that really should' nt be the case as you did'nt change any of the gain setting resistors.Maybe the extra clarity and lowered noise floor give the impression of more gain?

Next was like a veil had been lifted.

Thats what I would have expected ,op-amp design has come along way in thirty yrs.

Question: Do op-amps need a burn in time to sound their best?

Some hear changes they attribute to burn in but that has'nt been my experience.In my case I think there is an acclimatization period needed to adjust to the changes I'm hearing with different devices.

Fongolio

The gain thing puzzled me too but you are probably right about the lower noise floor leads to the perception of more gain.

I'm also hearing quicker transients. My son's first reaction was there was more bass. It also sounds better on streaming stuff from my comp as well. However the difference between 44,100 16 bit and analog appears greater now. Vinyl sounds considerably better now but I haven't played a cd yet through the Rotel with tube output. I'll report back when I do.

FTGV

Hi Kelvin,I'm in need of a few LM4562's for a project and was thinking of taking advanage of the free sample offer they have.Megasat kindly sent me a pair but I need a few more.May I ask how you went about ordering yours?


btw.Hows that C1 working?


Thanks Fred

megasat16

Fred,

I think National has LM4562 samples request here. I think you need to sign up with them.

http://www.national.com/pf/master_LM4.html

Good Luck with your next project!