Post your low power tube amps...

[Chubbles]

The Hotone Purple Wind is cool, but it is solid state. For some reason, I thought it was a tube amp.

 

[Alex_SG]

I think the only way they'd be able to sell them for less than $150 is to make them solid state. Not many tube amps to be had for that price point unfortunately....

 

[SG John]

I have a DST Engineering U84 TNT tube amp that has 2 EL84 output tubes, and is switchable between 2 and 8 watts. It sounds killer, and easily drives a Sovtek 2x12 cab.

 

[ninjaking67]

SG John, surprised it's only 8W from 2 EL84s. Most twin EL84 amps are in the 15-18W range. My Trinity Plexi is 18W from 2 EL84s.

 

[SG John]

SG John, surprised it's only 8W from 2 EL84s. Most twin EL84 amps are in the 15-18W range. My Trinity Plexi is 18W from 2 EL84s.

They could be separate channels. I have no clue. The JJ's sound good, but I may eventually throw some Siemens or Telefunken EL84s in it. I love how the Telefunken EL84s sound in my DST-30.

 

[67plexi]

SG John what's your B+ voltage on your EZ81 pin # 3 and the plate voltage on the EL84'S pin # 9 and output transformer voltage pin # 7
I used a 290-0-290 power transformer Radio Spares Clone on my EF86 TMB build.

 

[syscokid]

SG John, surprised it's only 8W from 2 EL84s. Most twin EL84 amps are in the 15-18W range. My Trinity Plexi is 18W from 2 EL84s.

I could easily be wrong on this, but if those pair of EL84s are in a single ended circuit, that would account for the "only" 8 watts. Can anybody else can confirm this?

 

[67plexi]

 

[syscokid]

DST's Bob sounds like a fun guy to deal with. Too bad he shut down DST a couple years ago. I hope someday I get a chance to experience Bob's "Marshall Killer", the U34-CL... "If you wanna be a Rock-n-Rolla"...

 

[67plexi]

I don't think it's a true class A more like a bridged Attenuator

 

[syscokid]

I don't think it's a true class A more like a bridged Attenuator

View attachment 3468

I have no clue what's happening here. Is there a "truck drivers" summary available?

 

[67plexi]

OK on the output transformer to the speaker out you see the Attenuator that's how the 8 watt 2 watt.

 

[SG John]

SG John what's your B+ voltage on your EZ81 pin # 3 and the plate voltage on the EL84'S pin # 9 and output transformer voltage pin # 7
I used a 290-0-290 power transformer Radio Spares Clone on my EF86 TMB build.

View attachment 3421

I have no clue. How do I know which is which?

 

[syscokid]

I have no clue. How do I know which is which?

Expose the inside of the amps chassis.
Plug and turn the amp on.
Zero out the volumes.
Take your digital volt meter and ground the ground probe to any grounding point on the chassis.
Set your meter to DC volts.
With one hand holding on to the hot or positive probe (keep your other hand or other body parts away from the chassis), make contact with each lug that corresponds to the pin number that 67plexi was asking about.
Observe voltage readout... should be about 400vdc, give or take about a 100v.
Both type of tubes are 9 pins... just like the preamps:


Before you attempt this, can you include me in your Will and give me first dibs on your guitars and amps...

 

[67plexi]

SG John you have a 290-0-290 PT or 300-0-300 PT B+ DC voltage should be 315-320 range under load.

 

[SG John]

DST's Bob sounds like a fun guy to deal with. Too bad he shut down DST a couple years ago. I hope someday I get a chance to experience Bob's "Marshall Killer", the U34-CL... "If you wanna be a Rock-n-Rolla"...

He's a hot ticket. Once his kids were done with college, he decided to retire. He still has his real job. He lives a couple blocks from me. I got to play the "Marshall Killer" and the MarWatts before I decided on the DST-30. I wanted an AC-30 built the same as Rory's early AC-30 that he used in Taste. Bob definitely delivered. I can't begin to say how awesome that amp is.

Expose the inside of the amps chassis.
Plug and turn the amp on.
Zero out the volumes.
Take your digital volt meter and ground the ground probe to any grounding point on the chassis.
Set your meter to DC volts.
With one hand holding on to the hot or positive probe (keep your other hand or other body parts away from the chassis), make contact with each lug that corresponds to the pin number that 67plexi was asking about.
Observe voltage readout... should be about 400vdc, give or take about a 100v.
Both type of tubes are 9 pins... just like the preamps:
View attachment 3481

Before you attempt this, can you include me in your Will and give me first dibs on your guitars and amps...

SG John you have a 290-0-290 PT or 300-0-300 PT B+ DC voltage should be 315-320 range under load.

I'll try to take a peek this weekend.

 

[SG John]

I don't think it's a true class A more like a bridged Attenuator

There wasn't anything that looked like those ceramic resisters, but there were a bunch of resistors sitting next to the toggle switch.

The B+ was about 8.5 Volts DC
Pins 7 and 9 were running about 243.5 Volts DC

Before you attempt this, can you include me in your Will and give me first dibs on your guitars and amps...

As much as she doesn't deserve them, the wife gets them first. Sorry.


Here are some photos to peruse.

 

[syscokid]

There wasn't anything that looked like those ceramic resisters, but there were a bunch of resistors sitting next to the toggle switch.

The B+ was about 8.5 Volts DC
Pins 7 and 9 were running about 243.5 Volts DC

Well, don't bother looking for pin 3 on the EZ81 tube because this amp is solid state rectified. Which means it does not have an EZ81 rectifier tube. You can measure the B+ at the filter cap lug or terminal I indicated at. Make sure the amp is operating at the full power setting and measure again.


BTW:

As much as she doesn't deserve them, the wife gets them first. Sorry.

 

[syscokid]

Or measure the B+ here... which should be easier to get to:

 

[67plexi]

I could be wrong or if I was in China I could be Wong.