Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jammied on June 22, 2020, 05:52:05 pm

Title: 18 watt lite. Brown note. Problems
Post by: jammied on June 22, 2020, 05:52:05 pm

Hello all.


Been awhile since I have been on the board or doing any amp building.


So I had the parts for about 5 years to build another 18 watt lite. Got it put together but it has low volume/output. I used a pro junior power transformer and a vox ac 15 reissue output transformer. Also used the 18 watt lite brown layout.


Any it has low volume/output. Really fuzzy fizzy sounding. I never had a 18watt build do this. But it has been awhile.


So voltages are with the tubes installed and guitar and speaker plugged in.


B+ is 330v


V1 pin 1 and 6 are 216v
V1 pin 3 is .79v
Pin 8 is .79v
Forgot to mention I split the cathodes and they each have a 1.5k resistor


V2 phase inverter.


Pin 1 162v 100k
Pin 3 and 8 60.2v
Pin 6 154v 820 ohm


Do these look ok? I used the pro jr power transformer on alot of builds and never had a problem.


Cathode bias on el84's is 10.3v


Thanks for any help

Title: Re: 18 watt lite. Brown note. Problems
Post by: shooter on June 22, 2020, 06:10:44 pm

got the schematic you used?

fuzzy/fizzy sounds like connections without more to go on.  chopstick'n should get a reply

Title: Re: 18 watt lite. Brown note. Problems
Post by: jammied on June 22, 2020, 06:18:19 pm

Here is the layout


I have been poking around in it but nothing yet.


Kinda ugly in mine now lol been changing components and moving wires but I will get a pic of it

Title: Re: 18 watt lite. Brown note. Problems
Post by: jammied on June 22, 2020, 07:58:03 pm

Well after further review..... I just had it turned up to much on the volume. So it went straight to brown sound lol. Turned down the volume some and it started singing.


Although I couldn't find the 3 .01 caps for the phase inverter and used .022 instead. Now I found the .01's so will swap them out and hopefully get a touch brighter. And maybe reconnect the v1 cathode caps.


I broke out my fender bass breaker 15 and it sounds a little dead unlively compared to the 18watt. The 18watt takes the place of low gain setting and medium gain setting of the bass breaker. And I think the bass breaker 15 is about the best amp fender put out for a long time! It's more marshally than most Marshall's that marshall puts out.


So if I'm correct changing to .01 from .02 on the phase inverter should brighten it up some?