The Amp Garage

A reverb tranny out of a Fender (stand alone) reverb tank should be close enough to okay for an ECL86 driver. Found a schematic for a standalone fender reverb unit model 6G15 that uses the 125A12A transformer with a ratio of 7.5K/8ohms according to a clone that hammond makes(1750AX). Its the second...

Ah! Good info right here

Thx.

Most Fender reverb driver transformers are wound to reflect around 18k to 25k According to the ECL86 datasheet, the anode load resistor of the pentode stage, in class A, should be arround 7k to 10k. I've got 2 NOS Philips ECL86 lying around that should not be used with this transformer correct? I h...

Yes, you pick the transformer for the reverb pan. Basically the transformer is designed for an output of a 12A*7 type tube, maybe in the 10k ish range, and outputs either 4 or 8 ohms or whatnot. Then you couple that with a tank of the same ohms and you're in business. Most common fender amp reverb ...

I've been searching for a really long time but no one seems to say either the reference of the reverb tank or the transformer in this schematic. As you know, reverb tanks have different specs and there are lots of different ones. I know that the transformer is some fender type but what is the specif...

Same here. Firefox uses the very accurate Google blacklist. https://www.stopbadware.org/firefox?hl=pt-PT&url=http%3A%2F%2Fampgarage.com%2Fforum%2Fviewtopic.php According to them it is up to the owner to resolve this issue and there is also a big chance that malware still exists somewhere on the foru...

Well i delievered the amp after much testing and consideration. Shit happens but nothing makes me believe those 6V6 will fail anytime soon. The OT is a 50 watter that, just by looking at him, i swear it can handle much more power. Its sounding very good. When the owner makes the video i asked him, i...

pdf64 wrote:

I will probably have more questions but so far the amp is sounding great.

Yes, it sounds great, well done!

Thank you!

So we all agree that under these conditions the JJ's will perform well but won't last longer than other tubes with more, let's say, "friendly conditions" right? The truth is that JJ does not provide any usable data about this tube so we can be more sure of ourselves when trying to develop an amp. I ...

Everybodys effort to help me is really appreciated. I've made some more measurements. Everything was measured using my digital multimeter and with an eye on the waveforms looking for ripple, clipping and what not. The tubes are biased at 9.3Watts. With the amp idle, i've got 433V on the plates and i...

If you are measuring one tube's current at a time the waveform there is something like half-wave rectified AC, which your meter may not handle very well. Not sure i understood it very well... are you talking about ripple? I am aware that the meter can give me a false reading on a half rectified wav...

martin manning wrote:How did you measure the voltage on the cathode current sense resistor? Using an oscilloscope would be best.

I used a digital multimeter, not sure i can trust the calibration on my poor old tektronix.

Anyone?

mmmm... it's around 68V peak to peak with an oscilloscope and 34Vrms measured with a voltmeter. 68v peak to peak has to be 34v peak. RMS = .707PEAK = 24 Your scope and meter do not agree with each other. Actually i believe the scope and the meter do agree with each other but in a different manner.....

mmmm... it's around 68V peak to peak with an oscilloscope and 34Vrms measured with a voltmeter. 68v peak to peak has to be 34v peak. RMS = .707PEAK = 24 Your scope and meter do not agree with each other. I was using my memory wich can be deceiving since it was 4am when i was doing the testing. Let ...