Tube Amp Archive

Gibson used the similar solution for the reverb in their Falcon amps from '60.
7199 tube was used, triode + pentode in one tube.

Rigol DHO804
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Replaced that old 5Y3 with a new one and no change, ramp up the voltage on variac to get 310 on anodes of output tubes but no real change, now is clipping at 8V on 8R load.
Also tried to connect signal directly to grids of output tubes, to bypass the whole preamp, but no change.

With 300 AC on a 5Y3 you should have over 320 VDC available. I can’t see why you have only 300 VAC when a GA-6 with two 6V6s has 320 VAC on its 5Y3 and over 330 VDC on the output tube plates. Do you have a known strong good testing 5Y3 to put in, or even a 5AR4 if your first PS filter will take the...

What do you have for wall outlet voltage if your in the US I would think that with today’s voltages of above 117 in many locals that you would have more then 6.17 VAC showing up for the filaments. If you lift one end of C4 when the amp is into clipping do any improvements take place? Any changes ta...

Heater voltages are constant 6.17VAC, no matter if the signal is clipping or not.

I just checked:
Anode voltage is 290V and Cathode voltage is 19V, without any signal on input
with the signal at input, amp starts to clip on 7.6 VAC on output (8R load), Anode voltage drop to 278.5V and Cathode voltage rise to 22.3V

this is a cathode biased amp
I will check later today once more is there any difference in anode voltages before and after the clipping, but I think from my memory it was couple of volts down, nothing major

I just got old Epiphone EA-28RVT from '60. Basically same amp as Gibson Falcon GA-19RVT. Sounds good but have early break up. Measured all voltages on the tubes from the schematic in everything looks fine. Also checked all signal capacitors for leakage. All electrolytic capacitors replaced and all r...

quick update
issue resolved, reflow again all the connection on the main PCB, this time reflow main IC chip and fresh bath in isopropyl alcohol resolve the issue

Recently I got the Orange VT1000 tube tester with a problem. Tester fail every tube I tried. I think problem is with heater circuit. It goes only to 2V and then drop to zero with fail result. Checked all the connections, connectors, but I didn't find anything suspicious. Reflow everything, but no ch...

JBC or similar "clone" iron with cartridges
much better than previous generation with tips

probably something like this:
https://www.westfloridacomponents.com/S ... -0011.html

check here: https://www.thegearpage.net/board/index.php?threads/soldano-slo-30.2461427/post-36895796 It‘s just adding two relays and a stacked concentric 500k pot for the gain knobs. You can use a stacked concentric pot for the master as well, but for simplicity’s sake I just hardwired a 1M to groun...

I have also DE-5000 with the kelvin probes, highly recommended