Are Ceramic Caps Any Good For Audio?

[Vinylcafe]

Am am recapping an old TASCAM Portastudio 4 channel cassette deck.
The Record/Playback board is full of small value (22pf-330pf) ceramic capacitors.
I am no engineer, but have always read that this type of cap was kind of a lowest-common-denominator type of component.
Should I be replacing these with a film cap like WIMA, Vishay, etc?
Or do they poses properties that I want in the circuit and leave them alone?
On the other hand, was this a cost saving measure at the time, and would the deck benefit from a change-over?
Any thoughts welcome.

 

[slimecity]

Most of the time depending on the application, they will be fine.

I think you find they aren't in the signal path. There may be some that could benefit from using a poly instead, ie: to get better stability across transistor leads etc, but my understanding is that this isn't often.

 

[elnaldo]

I'd say let them alone. They are good for many applications.

BTW, If you have further questions, I know those machines quite well, I fix them all the time. I have 3 different portastudios in my shelf waiting for service right now.

 

[Vinylcafe]

I'd say let them alone. They are good for many applications.

BTW, If you have further questions, I know those machines quite well, I fix them all the time. I have 3 different portastudios in my shelf waiting for service right now.

Thanks elnaldo!
It's a 246 for my daughter.
All the rubber is ordered, will redo electrolytic caps board-by-board.
Good to know there's an expert in the house!

 

[elnaldo]

I rarely found bad electrolytic in this series. Just found bad caps in a 488 MKII power supply. Actually I never faced a recap in this machines due to labor costs, but doing it for yourself is different.

What I've found was dirty relays and worn input selector switches. I usually remove all the mini relays , open them and clean the contacts, and replace any switch that keeps giving trouble after cleaning it.

 

[Vinylcafe]

Yeah, that is on the list for sure.
A lot of pots, faders, relays and switches in the signal path.
With a complete recap, new rubber, etc. it's a big project.

 

[dr*audio]

Ceramic caps in that range are used for rf to prevent oscillation. They are very effective at rf and rarely go bad. Leave them alone.

 

[dlucy]

When I'm shotgun replacing or completely rebuilding a board and have a low value ceramic cap in the audio path, I use 5% tolerance MLCC ceramic caps with a C0G NP0 dielectric. That's supposed to be the best for audio frequency signals.

TDK and Murata make and Mouser carries such caps in 50V and 100V for cheap. Buying in quantity (I.e. ten at a time) helps, too.

Just my hobbyist OCD $0.02

 

[Bob]

down at the pf level there aren't a multitude of choices like at the uf level. so many
times its ceramic and lately (wasn't around in the 1970s) are the C0G mentioned above
and the alternatives are the silver micas.

 

[dlucy]

down at the pf level there aren't a multitude of choices like at the uf level. so many
times its ceramic and lately (wasn't around in the 1970s) are the C0G mentioned above
and the alternatives are the silver micas.

My first project was a tube based phono stage (Bruce Heran's Groovewatt) and it called for a close tolerance cap in the RIAA circuit. Not having much experience I looked for an exact value and could only find the silver micas and ended up paying something like $11 for each of them. Since then I've replaced dozens of low value ceramic caps in preamp, tone, phono and power amp stages using the cheaper, slightly less precise, much smaller MLCC caps at something like $0.11 each. Big learning for me back then and great to get a real experience with many different kinds of caps.

It is very good to know all your choices and silver micas and MLCCs should be on your go-to list for audio gear work.

 

[mhardy6647]

There are those who feel that the ceramic coupling capacitors used in EICO's HF-81 PP EL84 stereo integrated amp are a key to its fine sound. I am not one of those folks

-- I put Orange Drops in mine.

 

[Vinylcafe]

Ceramic caps in that range are used for rf to prevent oscillation. They are very effective at rf and rarely go bad. Leave them alone.

Roger that.
Won't touch 'em.

 

[granto]

I'd say let them alone. They are good for many applications.

BTW, If you have further questions, I know those machines quite well, I fix them all the time. I have 3 different portastudios in my shelf waiting for service right now.

Hey elnado, I have a few questions for you!

I'm servicing my old 414. Are there any caps you'd recommend replacing while I'm in here, even if I don't see any that are bulging?

Also, do you have any suggestions for when an input is noisy? Most are fine but one has a good amount of white noise even without an input in the jack, and I can remove it with the volume fader. I suppose it could be the output, too.

Any suggestions on what to clean? My faders are pretty sticky and I used Deoxit D100, without taking them apart, and it only partially worked. I think I'll take eveyrthing apart and really scrub.

I replaced the belts. Any other suggestions while I have it opened up?

Finally, have you found a replacement AC adapter that isn't noisy? The one I'm using doesn't seem to be that high quality, and the OEM adapters rarely show up on ebay.

Thanks for any advice you might have!

 

[Catmanboo]

You're responding to a years-old thread, (4+). He's from b-a, Argentina & last active on AK today, so he may reply. Your first post should've been in the introduction forum. That said, welcome to the biggest audio info source out there. Now, for that intro - git on it!

 

[granto]

OK thanks I posted an intro

 

[elnaldo]

Hey elnado, I have a few questions for you!

I'm servicing my old 414. Are there any caps you'd recommend replacing while I'm in here, even if I don't see any that are bulging?

Also, do you have any suggestions for when an input is noisy? Most are fine but one has a good amount of white noise even without an input in the jack, and I can remove it with the volume fader. I suppose it could be the output, too.

Any suggestions on what to clean? My faders are pretty sticky and I used Deoxit D100, without taking them apart, and it only partially worked. I think I'll take eveyrthing apart and really scrub.

I replaced the belts. Any other suggestions while I have it opened up?

Finally, have you found a replacement AC adapter that isn't noisy? The one I'm using doesn't seem to be that high quality, and the OEM adapters rarely show up on ebay.

Thanks for any advice you might have!

Hello. Those are complex machines and I usually just fix problems and perform speed and levels adjustments if needed, I don't do any recap or preventive maintenance due to labor costs. In your case, one noisy channel could point to some noisy semiconductor (op amp or transistor) or some leaky capacitor. The fact it is "pre fader" (I understand the volume fader mutes the noise) narrows the search to the first stage of the preamplifier. You need some tools to identify the problem, or some experience to narrow the suspects components without a precise diagnostic.

Regarding the adaptors, I never had problems using standard adaptors . Old school linear power supplies are usually silent. Newer SMPS can introduce noises in the audio chain, sometimes picked by other devices too, not only the portastudio. But it's not usually a problem down here. I've faced those noises just a few times. Most of the adaptors perform OK.

In any case, if you have further questions, I suggest you to start a new thread at the TAPE sub forum, explaining your problem, dedicated only to your machine.

 

[granto]

Hello. Those are complex machines and I usually just fix problems and perform speed and levels adjustments if needed, I don't do any recap or preventive maintenance due to labor costs. In your case, one noisy channel could point to some noisy semiconductor (op amp or transistor) or some leaky capacitor. The fact it is "pre fader" (I understand the volume fader mutes the noise) narrows the search to the first stage of the preamplifier. You need some tools to identify the problem, or some experience to narrow the suspects components without a precise diagnostic.

Regarding the adaptors, I never had problems using standard adaptors . Old school linear power supplies are usually silent. Newer SMPS can introduce noises in the audio chain, sometimes picked by other devices too, not only the portastudio. But it's not usually a problem down here. I've faced those noises just a few times. Most of the adaptors perform OK.

In any case, if you have further questions, I suggest you to start a new thread at the TAPE sub forum, explaining your problem, dedicated only to your machine.

Thanks so much for the response to an old thread!

OK, I posted in the TAPE sub forum another question. However, to wrap this up for posterity: Embarrassingly, after a bit more tinkering I realized the noise I was hearing was because I had my DBX switch set to Sync, so there was no DBX on channel 4, thus the output noise. Cheers.