Tube Amp Help!

gordon_39422

gordon_39422

New member
I have been playing through my Fender Hot Rod Deluxe for some time now, about 18 months, actually. I had to change the power tubes almost immediately, so I went with some JJ 6L6GC's... A HUGE improvement in headroom and it took pedals VERY WELL!!! Since I've relocated time and again, thanks to Katrina, I have'nt played out in about 8-9 months, well, the weekend before Katrina hit us, anyway.... lately, my amp gets tired after playing for a few minutes and I start experiencing volume swells when using pedals, and if I switch em off, my headroom is almost completely gone... I get a thin breakup that is cool in its own right, but just not what I want... Any suggestions? I have a new pair of power tubes on standby, but want to make sure that's the problem before I use em...

Thanks for the feedback!

Take Care,
Allen
 
Re: Tube Amp Help!

could be tubes. my advice is to throw the new ones in and see if that solves the problem. if it does, great. if not put the old ones back in and check the preamp tubes. if they are fine too, youll need to poke deeper or bring it to a good tech.
 
Re: Tube Amp Help!

Thanks Jeremy... Guess I'll quite farting around, roll the sleeves up, and jump right in!!

Take Care,
Allen
 
Re: Tube Amp Help!

Alright then... I ordered SEVERAL preamp and power tubes from Bob at Eurotubes and got the order in early this week... I have spent HOURS sorting through this amp and here is the currnet situation....

The amp plays well, loud, and clean... but after awhile it starts to lose volume and break up... the bias is REALLY low... at 12 o'clock I'm only getting about 50mv.. I have to dial in around 3 o'clock to get 68mv

I drained the caps and tore the amp entirely apart and did a VERY close inspection of each and every component on the PCB. No discolored or charred components, however I did see discoloration of the PCB itself. If you place a flashlight on the opposite side of the board and look at it there is a yellowish sign of troubles past. The solder doesn't quite match the other compnents either.. I purchased the amp second hand, so I suspect this damage was sustained and repaired prior to my acquisition of the amp... I tested the said components and the are up to par with the specifications of the schematics I downloaded...

I'm learning more and more on a daily basis, but am currently stumped... I will take it to a tech if I have to, but it seems this should be a straighforward problem from which I might be able to gain some experience... Of course, I'd need some help from the amp guru's here for this to happen...

Would anyone be willing to point me in the right direction or offer some new approaches to this problem? I would certainly appreciate it, and return the good deed in anyway possible! If additional information is needed, I'll gladly post my findings...

Thanks in advance for any assistance I might receive and thanks for checking out this rather lengthy post!

Take Care,
Allen
 
Re: Tube Amp Help!

Thanks for the feedback Steve... I've sent a cry for help at the fender forum as well, but things still seem kinda dry...

Most of the information I use has come from Justin's site.. That is a plethora of useful info for ANYONE learning about tube amps... Those who own Hot Rods just benefit a little more because of the specifics...

Thanks again,
Allen
 
Re: Tube Amp Help!

Have you thought about building a Hoffman type board for this amp? You can then incorporate upgrades to components and design.

If you like the sound and features this would be a great way to insure it will be bullit proof. Of course include better tube sockets mounted on the chassis, I have seen this done.

From what I under stand a lot of problems with those amps are the tube sockets and the ribbon connections, oh....not to mention the plastic input jacks.

It's not a bad amp and design, it's just made for mass production. There are so many weak points to the construction design and materials.

Think how much better it would sound with Mallory 150 and Orange drop caps and metal film resistors and full sized pots. The only problem would be mounting the solid state components, but I'm sure this could be figured out.
 
Re: Tube Amp Help!

BigDaddy said:
Think how much better it would sound with Mallory 150 and Orange drop caps and metal film resistors and full sized pots.
Click to expand...

Sozo caps are so, so much better sounding!
 
Re: Tube Amp Help!

I have been doing research for this very topic... Rebuilding the amp with better components and in a better Cabinet as well... Just wanna get it going now... I miss it!
 
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