So my last post was about this lovely Traynor YGM-3 and specifically what to do about that high EL84 eating plate voltage.
The solution I tried was to use the Sovtek EL84M, rated for higher current and a whopping 500V on the plate. The amp left here sounding lovely.....
But, well, that didn't work. In this business one is always experimenting, largely to keep the cost reasonable. This is an expensive business. And I don't like seeing a customer return for a long time. It's not ideal for them especially.
And I'll just say it. I'm not here to sell anything, not even my services. So I can be honest here.
New tubes suck. It's just a fact we need to live with. The world will never produce another RCA, Mullard, Tung Sol, Western Electric, General Electric, Mazda, National Union, Amperex, Brimar or genuine Telefunken tube again. There is absolutely no incentive to do so. We need to live with the mediocre in this world now. Music is changing, the world is changing. There will be no exceptional tubes ever made again much like there may never be another platinum record again. It's over. Music is free, the population of guitar players and audiophiles is diminishing. I love tube amps. I find them fascinating so I carry on. And I will play music till the day I die and I will sound my best till then so that is that.
So what happened? My client got home and rocked it out for a couple rehearsals. It sounded great then it ceased to sound great. One tube totally died, the other test about 1/2 on my TV7 tester.
Not acceptable.
There are several ways to drop voltage. Zener diode, dropping resistor. But I don't like those methods. Since my client wants this to be road ready we opted for the most expensive route: changing the power transformer.
I used a nice Canadian made Hammond, part number 270DAX. I write this so I can have a record of it. If I see another amp I can just tell them their options if they want reliability.
With the original transformer the B+ sat around 425-440vdc. With this part depending on bias its between 329-345vdc. About the same range as your Blues Jr. Those run hot but they are reliable. I think this is a safe range.
You do lose a few watts. But the amp sounds as good as it did before, a tad warmer my ears say.
Nice thing about this part is it's the same size as the original. You need to get creative with some washers to run the heater wires around to the chassis hole, drilling is not an option here, and with that I had no need to drill anything. It's a 520 vCt transformer so you'll need to take out the 2 diodes going to ground and put the red/yellow CT wire to where the diodes terminated otherwise you'll have some seriously high voltage problems!
Once that's done you'll need to change the bias resistors until you get an acceptable range. In this case I changed the 18k coming off the AC feed to a 10k and replaced the 22k with a 7.5k tied in series to my 20k trim pot. Now the amp is sitting at 329vdv with 22ma on the output tubes. That's about where a Blues Jr sits.
So in conclusion, if you have one of these this is a good path to reliability unless you have the dough for genuine 7189 tubes. It's worth doing. I still maintain this is a great amp. Now it's a great amp for modern times.
JB
The solution I tried was to use the Sovtek EL84M, rated for higher current and a whopping 500V on the plate. The amp left here sounding lovely.....
But, well, that didn't work. In this business one is always experimenting, largely to keep the cost reasonable. This is an expensive business. And I don't like seeing a customer return for a long time. It's not ideal for them especially.
And I'll just say it. I'm not here to sell anything, not even my services. So I can be honest here.
New tubes suck. It's just a fact we need to live with. The world will never produce another RCA, Mullard, Tung Sol, Western Electric, General Electric, Mazda, National Union, Amperex, Brimar or genuine Telefunken tube again. There is absolutely no incentive to do so. We need to live with the mediocre in this world now. Music is changing, the world is changing. There will be no exceptional tubes ever made again much like there may never be another platinum record again. It's over. Music is free, the population of guitar players and audiophiles is diminishing. I love tube amps. I find them fascinating so I carry on. And I will play music till the day I die and I will sound my best till then so that is that.
So what happened? My client got home and rocked it out for a couple rehearsals. It sounded great then it ceased to sound great. One tube totally died, the other test about 1/2 on my TV7 tester.
Not acceptable.
There are several ways to drop voltage. Zener diode, dropping resistor. But I don't like those methods. Since my client wants this to be road ready we opted for the most expensive route: changing the power transformer.
I used a nice Canadian made Hammond, part number 270DAX. I write this so I can have a record of it. If I see another amp I can just tell them their options if they want reliability.
With the original transformer the B+ sat around 425-440vdc. With this part depending on bias its between 329-345vdc. About the same range as your Blues Jr. Those run hot but they are reliable. I think this is a safe range.
You do lose a few watts. But the amp sounds as good as it did before, a tad warmer my ears say.
Nice thing about this part is it's the same size as the original. You need to get creative with some washers to run the heater wires around to the chassis hole, drilling is not an option here, and with that I had no need to drill anything. It's a 520 vCt transformer so you'll need to take out the 2 diodes going to ground and put the red/yellow CT wire to where the diodes terminated otherwise you'll have some seriously high voltage problems!
Once that's done you'll need to change the bias resistors until you get an acceptable range. In this case I changed the 18k coming off the AC feed to a 10k and replaced the 22k with a 7.5k tied in series to my 20k trim pot. Now the amp is sitting at 329vdv with 22ma on the output tubes. That's about where a Blues Jr sits.
So in conclusion, if you have one of these this is a good path to reliability unless you have the dough for genuine 7189 tubes. It's worth doing. I still maintain this is a great amp. Now it's a great amp for modern times.
JB
