Bad Cat hot cat build?

[chuckb]

Hey guys, I have a schematic for the bad cat hot cat 30 and I'm not to sure how to read it. It has 4 12ax7's which are split into v1a-v1b,v2a-v2b etc. My question is which side of the tubes are the "A" side and which side is "B" side? The gain channel goes to V1a,is the cathode on this side pin#3, the plate pin#6,the grid #7? The clean channel is on V1b in which The cathode is pin#8, the plate pin#1 and the grid is pin#2? Is this the sequence for all the preamp tubes? Thanks in advance.

Chuck.

[loudthud]

The designation of "side A" and "side B" is arbitrary. It could vary from amp to amp. Your other questions are answered by looking at a manufacturers data sheet. You should learn how to read these and become familiar with them.

NJ7P Tube Database Search

[chuckb]

Hey Loudthud, thanks for the reply. Here is a link to the schematic I have for the Bad Cat Hot Cat 30. Perhaps you can help me make the distinction between which pins I'm to use in each tube?http://www.schematicheaven.com/newamps/badcat30.pdf

Chuck.

[Bruce / Mission Amps]

Chuck the link didn't work for me....
but as Loudthud is saying... it doesn't really matter, the actual elements in the two triodes are not connected to each other and as long as you know what #1 and #6, #2 and #7 and #3 and #8 lugs are, then you just wire it up.

[chuckb]

Bad Cat Schematics or Adding Reverb to Matchless C-30 - Boutique Amps - All - Amp Workshop - Message Board Yuku Here is the link again.

chuck.

[chuckb]

Hey Bruce, here's another link. I think I forgot some underscores in the last one. http://www.schematicheaven.com/newam..._hotcat_30.pdf
Hope this one works.

chuck.

[jimboyogi]

Chuckb,

If you look closely at some 12ax7 data sheets they mention that the lowest hum is on triode is pin 6,7,8. So it's probably worth making this V1a (the input triode or first gain stage).

Although I don't know how much difference it makes in practice, at least you'll know you did the recommended thing

[chuckb]

Hey thanks for the reply. I've already started the build and what you suggested is exactly what I've done.

Chuck.

[chuckb]

Hey guys ,
The link i sent of the Bad Cat Hot Cat schematic,on V4b where do the 100k cathode resistor go? Do it tie into "D" , the same as V4a or does it go to ground? The schematic doesn't show where it is to go. Thanks in advance.

Chuck.

[jimboyogi]

Hi Chuckb,

The 100k resistor is a plate (or anode) load resistor, and would go to power supply point 'D' like the one on V4a.

[loudthud]

Did you notice the other mistakes on the schematic?

[chuckb]

Hey loudthud, I did notice some other things like where does the lug on the master volume pot go? Also the lug on the Edge pot I'm assuming goes to ground. Is the standby switch in the right place? I thought this amp had a 1/2 power switch though I don't see one.I see that the switch is there for the ss/tube rectifier but I'm confused by the way it's wired. It looks like the 100uf/450 filter cap ties into it in the center? is this one spst switch or is it two? Looks like the switch that the "E" line coming off the choke is tied to a seperate switch? Is there any 1/2 power switch on this schematic? Any mistakes that you can find ,could you pass let me know? I appreciate your input very much.

Thanks,
Chuck.

[loudthud]

It is unclear to me how the Master Volume should be connected. As shown, it won't be able to shut the signal all the way off and will just have a slight affect (2dB) on the overall volume. I would connect it as shown in the attachment.

The Edge pot is ok as shown. It will act like a treble cut control. Just leave the lug unconnected.

The standby switch will work just fine. There is the Solid State/Tube switch that you may have mistaken for a half power switch. That switch should be a DPST or DPDT. It's hooked up in a strange way, but does a neat thing the way it connects an extra cap in the Solid State mode. It might have been done that way to get around a Mesa Boogie patent.

Did you notice that most of the Gain Preamp isn't grounded as it should be? There needs to be a ground, probably near the input jack if an insulated jack is used.

Two resistors on the Gain channel input need to be swapped for the Grid Leak bias to work as it should.

It's not really shown on the schematic but pin 1 should be connected to pin 8 on EL34s.

I can tell from your questions that you can't read schematics very well. I suggest you invest in some books on elementary electronics to expand your knowledge, understanding... and safety . I know it seems boring to read about batteries, light bulbs, switches and resistors but everybody has to go through it.

[Gibsonman63]

Chuckb,

If you look closely at some 12ax7 data sheets they mention that the lowest hum is on triode is pin 6,7,8. So it's probably worth making this V1a (the input triode or first gain stage).

Although I don't know how much difference it makes in practice, at least you'll know you did the recommended thing

I have never heard this before. Is there an appreciable difference? Why would one half be quieter than the other half? Do the classic Fender and Marshall designs follow this convention?

...engineering minds wanna know!

I am not intending to highjack the thread. If my little query starts to take on a life of it's own, I will start a new thread.

[chuckb]

Hey Loudthud,
Yes, I need to learn more on schematic reading.I'm pretty new to this amp building. I do have several books on amp building from Kevin O'Conner which I find very helpfull.This is my fifth build and the most difficult yet. I have built a 5e3,5f6A,Matchless lightning,and another that was my first, and very simple to do,much like a champ circuit. I am very carefull and safety is always my first priority. I have looked here to the forum for alot of help along the way. Thanks for your help,I appreciate it.

Chuck.