Is this a ceramic?

[12AX7]

I want to try a ceramic treble cap but i don't want to order one, pay $5-10 for a 2 cent cap and wait a week or 2 for a cap that very well may be a waste of time/$. So i looked for one on some old pars boards i save and i found these which i can parallel to get 250pf. But i'm only familiar with ceramic as those non glossy yellow caps. I do realize some are epoxy dipped tho and wondered if theres are ceramic given the fact they are round like ceramics i'm familiar with are. Some have voltage on them so i know the are fine for the tone stack and i used my meter to determine the values. I just need to know if they are ceramic.

[bmccowan]

Google or any other search engine - 10 seconds:
https://www.alldatasheet.com/view_datasheet.jsp?Searchword=CD101K&sField=1

[12AX7]

thanks. I thought that was just some generic number that wouldn't refer to a particular type. Anyways i tried it already and it was strange how different it was, tho not necassarily in a good way. It changed the variable NFB, presence, and treble controls to where they did a lot less. I checked several times and it was right around 300PF. My amp also has a pull pot that switches between 250 and 350pf treble caps and formerly between 250 and 500pf, so i am very familiar with how changes in value affect the tone and this was very different. Seemed like it was passing much smaller amount because the amp also seemed less loud. Again, i checked and rechecked and it was right around around 300pf. Strange. I wouldn't say it was smoother because there was much less top end when at the settings i usually use and had to have the treble/NFB/presence turned up considerably to get as much top and then if anything was less smooth. I also found a huge ceramic i forgot i has thats the flat yellow type and is 500pf and while i don't care for the way the amp sounds with 500pf, it was definitely harsher than 500pf mica. So i dunno why my results were so different but i certainly didn't hear ceramic as smoother/less harsh.

[Lectroid]

FWIW, I just swapped out a 250pF mica cap in that position for a 270pf  ceramic in my BFDR clone.  It killed a lot of harshness and gives a much smoother sound.  I hear what you're saying; it's just weird I got a different result. Amps are funny animals.

[12AX7]

I see what was happening. The 2 caps in parallel are tiny and had short leads. So i hade to carefully try and solder them together then add lead length and apparent one cap leg wasn't making contact. So the value was around 150pf and thats why i had to crank treble with the treble pot, presence and variable NFB to get enough top end but it made it harsh. So now i'm getting normal results and yes, it seems a bit smoother but it's not a huge difference. But the amp is very good sounding and at this level of tone every little improvement you get can be quite notable. So i'll go ahead and order some. Any suggestions or do they vary? I notice a different in caps elsewhere by type and in come cases brand like sozo vs mallory. If no one has suggestions for a particular brand i'll just probably order whatever is cheap from china. I'm assuming the ones i am using are high enough voltage but i don't know for sure. (only the one i posted a pic of had any part # on it but that one is a large value. Ones i'm using don't have anything recognizable. Plus i'd rather get the proper value than have two paralleled caps.

[sluckey]

Unless you have a parts house next door or place a big order to offset shipping costs, this is probably about as cheap as you can buy one 250pF cap.

https://www.ebay.com/itm/144739189624?hash=item21b320c378:g:LZUAAOSwgohjMwkf&amdata=enc%3AAQAHAAAAoIVWvqxx3rH4Q8aLq%2Fvq0HcRPo5f8uPE3tc9xlMM033zdLjGbdZkkAluo3CsIbAx5BJh3KLm%2BQRRN0Hn50lKmu%2FM%2FzfjZxzyfYMx6TylUUrKfeE7%2BnI82m1dfgYq%2Bd2EhFe8Ae%2FV381wIumhzJ%2BRYnpA1OGVj4FrlMNym%2FMBhjpXlzmxFspHyY3m2VjUXM8qzMQMj2tCPbnlujhEbbb4yMc%3D%7Ctkp%3ABk9SR8yrkIuAYQ

[12AX7]

So one's the same as the next? If not that'll do. Thanks.

[sluckey]

NTE has been making quality caps for a long time.

This cap will likely have some pretty big DCV on one side so get at least a 500V cap. 1KV is very common for that size cap.

[12AX7]

Thats TEN caps for $6, right? You said one but it seems to say quantity is 10. Gonna order because i need to also put about a 100pf in parallel on a switch so i can choose 250pf or 350pf. Being 250 i can use 2 in series then parallel them with a switch and it's be a bit more at 375 total but thats ok. Plus at 10% i may be able to choose one close to 100pf.

[sluckey]

Thats TEN caps for $6, right?

That's what the eBay listing says.

i need to also put about a 100pf in parallel on a switch so i can choose 250pf or 350pf.

I bet that switch won't get much use after the first week.

Which amp circuit are you talking about?

[tubeswell]

In this hobby, it’s not unusual to quickly acquire large surplus numbers of parts from inability to curb minimum order quantities. To remain viable, electronic parts manufacturing is done in bulk and needs to be sold in bulk, and in the interim there a large stockpiles of unused parts awaiting your future order.

[12AX7]

Thats TEN caps for $6, right?

That's what the eBay listing says.

i need to also put about a 100pf in parallel on a switch so i can choose 250pf or 350pf.

I bet that switch won't get much use after the first week.

Which amp circuit are you talking about?

It will....i've had that switchable treble cap setup for quite a while and i use it a lot. One possible reason is that because the amp has so many options it's super flexible and that switch comes in really handy depending on how other things are set and which guitar i'm using. That extra 100pf is just enough to get into that more kraaaang territory from the smoother more transparent top that 250pf gives.  I really like having that option. The circuit is not copied but a result of messing with the preamp for years so it doesn't resemble anything too closely. The basic setup tho after the 3 stage cascaded  preamp is pretty much a marshall thing with cathode follower into a typical marshall tones stack but 6v6 instead of el34 with a wreck style OT.

[sluckey]

Got a schematic?

[12AX7]

Yeah but i need to update it since imade quiet a few changes since last it was up to date.

[12AX7]

heres the updated schematic. One thing tho....the 100pf that i switch in to get 350pf isn't a 100pf after all. I measured it and it read 186pf so given that my meter usually adds about 30pf, i assume it's a 150pf. It says 100 on it tho so it's either way out of spec maybe from overheating it with the iron or just defective. I tested it because i put a ceramic that reads 100pf on the switch and it made hardly any difference. I assume it's around 70pf given the meter's added capacitance. So the way i had it it was probably 400pf when switched in instead of 350pf. Maybe thats why u figured it wouldn't be of much consequence. EDIT: i missed one thing when i updated the schematic. NFB is on 8, not 4.

[Willabe]

I wonder if these are any good?

25pcs 1KV 2KV 3KV 5PF-100NF High Voltage Ceramic Industrial Capacitor | eBay

[acheld]

I wonder if these are any good?

No name Chinese parts?   They could be perfect; they could be shiite.  You never know until you test them in your build.

Not worth it for me.   I'd rather buy extra stuff at Mouser or Digi-Key and pay the shipping.  I know what I'm getting.   

[12AX7]

Sorry to bring this one back to the top, but i have another question regarding ceramics. Since the auction i bought on ebay is a 10 piece lot,  what about other areas in the amp? Do these tend to sound smoother than mica even in other parts of the circuit? Asking because i have several other micas as those marshall style 470k/500pf hi pass filters in the preamp and i can double up the 250pf ceramics in parallel to replace those micas. But will they smooth things out the way they do in the tone stack? Do those of you who like the smoothness over mica only find them to be worthwhile in the tone stack?

EDIT: conversely, I just got done reading a lot of posts in a google search "silver mica vs ceramic", now i wonder if i should use ceramics at all because i've read many posts sating ceramics are microphonic. That alone is worrisome, but add to that the fact that since i put ceramics in my tone stack i have gotten squeal where i normally don't at fairly low volume when hitting a clean boost for more drive and together those things make me wonder if i should. Especially since i have a band jam next weekend and i only do that about once every month or two and hat to ruin it is thats going to be an issue. I didn't think to connect the microphonics with the ceramics, i just figured the gain was too high but thinking back i didn't touch my gain settings on the pedal or amp.

[acheld]

Ceramic caps, as we use them in hand wired guitar amps, seem to be more prone to microphonics than others. But many components will sound off when you thump them -- and yet don't seem to cause problems when in standard operation. 

It's possible that the radial leads we use contribute to the problem of mechanical stress causing noise -- after all, surface mounted ceramic caps are used more often than any other type, and don't seem to cause problems much.

I like the modern metallized film capacitors myself for guitar amp building.   They seem to be very consistent, and I've had good luck with them.   

But, as with all components, you have to pick one that will do the job (and is sufficiently rated).

One can drive themselves batty by trying all the different types of caps!  Personal experience . . .