The Amp Garage

Hi Folks, Thanks for the insight and advise regarding the issue with my newest build. I switched the primaries on the OT and rewired the NFB. I shielded between the stages, shortened and rewired around the PI and re-routed the OT wires away from the PI. The amp instantly came alive! No hum, no crack...

Hi Darin, I would like to see the schematic for the power tube section. What component values did you use for the following compliment: EL34's Kt66 5881/ 6l6 I am using a full wave rectifier while the original uses the full wave bridge. I did this type build a while back very cool circuit...not sure...

Thanks folks for chiming in. I feel more hopeful... The feedback loop was never hooked up. Interestingly, on initial start up the amp was performing with some intermittent oscillation. Then I blew one of 5881 power tubes. I mistakenly thought that I had a problem with the power transformer. So I bou...

I will say that I was hasty with this build.

I have an oscope. But I have never used it so it will take some time to understand how to set it up.

For now I will try the caps on the output.

Is oscillation a result of poor wiring? What is the root cause of oscillation?

Thanks,
Danny

Well, I did some tweaking around the PI.

No real difference.

The amp volume will swell in and out.

When picking a note the amp responds to attack almost percussive but the note sounds terrible.

Could this be a bad transformer?

Danny

Hi Folks, Running into some issues with my recent build. I've been trouble shooting for last few hours but cannot find the issue. Th SD60 is running 5881 power tubes and 12ax7s on preamp. Symptoms are: Lacks power Flubby bass Strange harmonics at the end go the notes. Distorts at low volumes. I chec...

Hi Lou,

Well, after some digging, I found this link:

http://ampgarage.com/forum/viewtopic.ph ... highlight=

Might be more trouble than it is worth.

Perhaps I stay with full wave rectifier with choke.

Decko

Hi Gents, Thanks for your response! I wanted to try a full wave bridge rectifier with a choke. Is this transformer not capable of providing both full wave bridge rectification and a fixed bias circuit from the 350 VAC secondaries? Blue = 6.3 VAC Blue = 6.3 VAC Yellow=5 VAC Yellow=5 VAC Red=330VAC Re...

Hi All,

If I use a full bridge rectifier with the transformer listed below, how would I configure the bias supply for the two EL34's?

Here are my power transformer specs:

Blue = 6.3 VAC
Blue = 6.3 VAC

Yellow=5 VAC
Yellow=5 VAC

Red=330VAC
Red w/Blue Stripe=0
Red=330VAC

Thanks
Decko

Thanks All,

I will experiment with both!

again, thanks for the input!

Regards,
Decko

Thanks for your responses... How do you size your RLC or RC? I am building a Naylor SD60 with re-purposed parts. 4 12AX7 tubes at the preamp and pi. 2 EL-34's on the power section My power transformer gives me 330 VAC. OT is a Heyboer HTS-5122 50 watt, 3400 ohm primary. I havea Hammond 159P inductor...

Hi All,

Why would one use a choke over a large cement resistor? What are the design and tonal considerations?

Decko

Thank you for the responses.

The Trainwreck Express uses a full wave? yes?

Can you give a few popular amplifiers that use either method if rectification?

I would like to compare the circuit and see how I might experiment.

Decko

Why would one use a full wave bridge rectifier over a half wave rectifier? Or even a bridge rectifier?

What are the benefits of one over the other?

I have read that the full wave uses less filtering.

Just asking....

Thanks,
Decko

Hi All, Thanks for the kind words. I will get more detailed pictures when I install the new terminal block system. I machined a new set of aluminum brackets for the accessories which a plan to black anodize. I also received some new t-nuts which will make movement of components easier around the fra...