Need help with 50 Watt build!!!!!

jctaudiodesigns · Post by **jctaudiodesigns** » Fri Nov 30, 2007 8:21 am

Roe wrote: could it be that your bias is way high?
if so, replacing the 47k bias resistor with a 68k might help

I don't think its bias, I have no tubes in it yet. I am just in the voltage testing stage. Funny that all the voltages are good.

neikeel · Post by **neikeel** » Fri Nov 30, 2007 1:43 pm

jctaudiodesigns wrote:Well the trouble shooting begins, last night I disconnected the wires that send power to the choke and the OT and no popping. This morning I think I will put the OT lead back and see what happens.

Sounds like you are narrowing it down a bit (internal short in choke or OT) or faulty joint on an out put socket?

jctaudiodesigns · Post by **jctaudiodesigns** » Fri Nov 30, 2007 5:31 pm

Ok, I went ahead and re-soldered the choke wire back on, leaving the output transformer out, and the popping came back. Next with the output transformer still disconnected, and the choke connected, I pulled the ground wire off the other 50/50 filter cap and NO POPPING!!!! There is a store close to me that stocks the JJ 50/50 cans and I am going to replace both of the CE 50/50 filter caps with JJs tonight when I get home.

jctaudiodesigns · Post by **jctaudiodesigns** » Fri Nov 30, 2007 10:03 pm

Ok gentlemen, it does look like it was a bad filter cap!!!!!!!! Just replaced it and I now have a very quiet amp!!!! I will let you know how is sounds in a bit!

thousandshirts · Post by **thousandshirts** » Fri Nov 30, 2007 11:08 pm

Right on!

I've been following this one with interest, knowing you'd get her up eventually!

Will

jctaudiodesigns · Post by **jctaudiodesigns** » Sat Dec 01, 2007 12:20 am

Ok, so I am almost there! I now have tubes in it and channel 2 sound wonderfull!!!!!!!!!

However, Channel 1 needs help. It is really hissy and when I plug into the top jack and turn up the volume a little, I get a LOT of hum and its kind of screachy if that makes sense. I tried changing the preamp tube but thats not it. Any Ideas?

jctaudiodesigns · Post by **jctaudiodesigns** » Sun Dec 02, 2007 2:24 am

Problem fixed, it was a bad ground on my buss wire. I took an extra ground lug that I had and put it under one of my circuit board anchors and then took some of the extra buss wire to go to the buss. Seems to work great!

I found the bright channel really way too bright, so I have removed the bright cap all together.

Roe · Post by **Roe** » Sun Dec 02, 2007 12:43 pm

some of the brightness can go away when its broken in

mwm523 · Post by **mwm523** » Sun Dec 02, 2007 12:45 pm

jctaudiodesigns wrote:Problem fixed, it was a bad ground on my buss wire. I took an extra ground lug that I had and put it under one of my circuit board anchors and then took some of the extra buss wire to go to the buss. Seems to work great!

I found the bright channel really way too bright, so I have removed the bright cap all together.

Glad to hear you got it all sorted out! I have removed the bright cap from mine as well.

Have fun with your new amp. You should get extra pleasure from it knowing you had to work through a problem to get it working well. Congratulations!

Post by **Scumback Speakers** » Sun Dec 02, 2007 1:43 pm

Mike (mwm523), I started with the 250 pf cap and now I'm thinking 100 or none. What did you hear when you had the amp volume on 7-8? At that point I'm jumping channels and dialing in the II channel to around 9 on the volume knob, and Ch I around 7-8.

I find the amp is really bright on Ch I, and it will probably help if I remove the bright cap altogether. Does Ch I still stay a little more trebly than Ch II if I remove the bright cap from the circuit? Lemme know, sir. Thanks!

Jim

mwm523 · Post by **mwm523** » Sun Dec 02, 2007 2:03 pm

Jim, I started with a 250 also, then switched to a 100 which I liked much better, but was still a little too bright for me at volumes below 7. I've since removed it and I'm enjoying it much more.

With the 250pf in mine, I had to get channel 1 up to almost 9 to smooth out the brightness. With the 100pf it smoothed out between 7 and 8. With no cap, I'm getting nice warm smoothness even lower than that.

And yes, channel 1 is still quite a bit brighter than channel 2 even with no bright cap on the pot. This is largely due to the 500pf cap across the channel 1 470K mixer resistor (which is essentially another bright cap).

bartak · Post by **bartak** » Sun Dec 02, 2007 5:19 pm

I took my bright cap off also but after I put the PPIMV in I went back up to the 250 cap and may go with the 500. playing in a room by myself I like the lower value or no cap but with the band the higher value cap helps cut through the mix and open the amp up. One of the best things I've learned from playing shows is find the tone that sounds good to your ears then add a little treble and mids, It may sound a little harsh in front of it but it will translate to the audience much better. also the ear plugs that you all should be wearing in front of one of these amps turned up, helps cut some of the highs.

jctaudiodesigns · Post by **jctaudiodesigns** » Sun Dec 02, 2007 7:34 pm

Wow, ok now I have an amp! I ordered a TSL 100 that was modded by Voodoo amps a couple of months ago, I spent a lot of money on that amp, now I am kicking myself. I will NEVER buy a major manufactures amp again. I am now wondering If I can design my own high gain amp. Maybe add a extra gain stage. My mind is going at 100 miles an hour. One thing is for sure, the TSL is going on ebay.

What should I build next?

jctaudiodesigns · Post by **jctaudiodesigns** » Sun Dec 02, 2007 7:44 pm

Southbay Ampworks wrote:Mike (mwm523), I started with the 250 pf cap and now I'm thinking 100 or none. What did you hear when you had the amp volume on 7-8? At that point I'm jumping channels and dialing in the II channel to around 9 on the volume knob, and Ch I around 7-8.

I find the amp is really bright on Ch I, and it will probably help if I remove the bright cap altogether. Does Ch I still stay a little more trebly than Ch II if I remove the bright cap from the circuit? Lemme know, sir. Thanks!

Jim

Hi Jim,

Yes it does stay quite a bit brighter, than channel 2. I may replace the bright cap later with a smaller value. I will have to see what it sounds like when it breaks in. Right now it sounds great!

mwm523 · Post by **mwm523** » Sun Dec 02, 2007 8:08 pm

jctaudiodesigns wrote:Wow, ok now I have an amp! I ordered a TSL 100 that was modded by Voodoo amps a couple of months ago, I spent a lot of money on that amp, now I am kicking myself. I will NEVER buy a major manufactures amp again. I am now wondering If I can design my own high gain amp. Maybe add a extra gain stage. My mind is going at 100 miles an hour. One thing is for sure, the TSL is going on ebay.

What should I build next?

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