reverb built in plexi

[michalm]

Hi guys,

First of all I would like to thank you all for keeping and maintaining such a place.
It is a great benefit in an internet area to spread knoledge and learn things. With out such a places I would be not able to do anything.

Yesterday I finished my little project to built in a fender reverb model 6g15 in my plexi clone (45W). I was so happy everything was working fine at home until my first gig yesterday...Amp with a higher output was not playing good. After almost 2 hours my HT fuse blow off.
I checked at home and found out that the first of the 10k (5W) resistor in PSU was getting really hot .
I have about 400 v after choke and I had to lower it up to 300V wich is shown in a Fender Reverb schematic. Reverb unit is consuming about 21 mA.

My question is if it is possible to go directly with 400v to the 6V6gt via 125A20B transformer?

How can I lower the voltage?

Thanks in advance.

[Reeltarded]

6 K 6GT and I don't think so.

What is your schematic? You can do a mixer input and recovery stage that is fairly neutral with an ax7.

[michalm]

Thanks for quick reply.

My clone is similar to mark`s 50 watt lead. The schematic is not 100% I did some changes in a preamp to have also JCM800 chanel. Between PI and tremble there is FX Dumbleator + Reverb unit.

There will be not a problem installing 6K6 for a reverb transformer?
Transformer is 25k Ohms primary.

Regards,

[VacuumVoodoo]

I checked at home and found out that the first of the 10k (5W) resistor in PSU was getting really hot .
I have about 400 v after choke and I had to lower it up to 300V shown in a Fender Reverb schematic. Reverb unit is consuming about 21 mA.

My question is if it is possible to go directly with 400v to the 6V6gt via 125A20B transformer?

How can I lower the voltage?

Thanks in advance.

"lower it up" - I like that

21mA into 10k resistor burns ca 4.5W. You need at least a 10W or even better, a 15W resistor firmly attached to the chassis.
However: 6K6 anode current does not pass through this resistor, there's is only max 5mA there, so only 250mW is burned off as heat. That resistor should not get hot. Unless there are other parts of your amp sucking current from this spigot.
QUESTION: Did you give us all the information? A complete circuit diagram would help to help you.

[michalm]

Hi VacuumVoodoo,

Unfortunately I have no schematic for a full amp
Generally speaking schematic is really simple:
Hammond transformer 372jx (2x300v 288mA) - standby switch-rectifier switch(tube/diodes)
- 32uf cap to OT and 10H choke than 32uf cap to g2 of kt66 + reverb unit (schematic attached)+ PI via 10k resistor .... preamp section.
Amp was working fine before I start to built reverb in. Reverb is exactly like on above Fender schematic. It is quiet(no hum) and beautiful warm sounding. I didn`t notice anything wrong. The only problem is resistor which is going to a first cap (40uf) of reverb... It is getting hot.

I found one 4k 22 W resistor and I replaced the one installed(5W). After 20 minutes of running the amp new resistor was hot. It was not so hot like 5W at least I was able to touch it

I am not very familiar with a single ended but I wonder if this 6v6 tube in a drive can hold 400 Vdc. Maximum anode voltage for this type of tube is 500 V in a pentode mode.
Reeltarded suggested 6K6 GT tube.

Regards...

[thejaf]

Use a 12AT7 or 12AU7 instead. 6V6 in SE Class A pulls a whole lot more current. Look at AB763 schematic

[Reeltarded]

I didn't mean to suggest a 6K6, it is the tube in your Fender scheme.

[VacuumVoodoo]

I found one 4k 22 W resistor and I replaced the one installed(5W). After 20 minutes of running the amp new resistor was hot. It was not so hot like 5W at least I was able to touch it

If it's not leaving blisters or dark red spots on your skin it's ok. If it's hot enough to fry eggs on then you're in a pickle.

I am not very familiar with a single ended but I wonder if this 6v6 tube in a drive can hold 400 Vdc. Maximum anode voltage for this type of tube is 500 V in a pentode mode.

JJ 6V6GT can take it. Pull screen grid voltage down to below 300V for good measure.