ac30 build low volume

[magnusandmilo]

Hello
I recently built an ac30TB6 Clone using MM trannys, choke, webber chassis, sozo caps etc.
The build went great, everything is neat and tighty. The power up went fantastic as well, no blow fuses and Voltages look great. It dose run very hot (16 watts dissipation) but from what I have read that is normal for the ac30 and tube life suffers.
The amp sounds great and is quiet but there is not very much volume (all channels). All the way up sounds like it should be about half. I have a 5e3 that sounds louder.
I have check and checked resistors pots etc.
I am pulling my hair out.
Does any one have any suggestions?
I have tried multiple guitars, speakers, cables, and tubes.
Thanks
Any thought would be great I am at a dead end!

[pdf64]

I'm not clear whether the issue is that the amp has low gain or low power output, eg the amp doesn't have enough gain to overdrive, or it's overdriving at low power outputs?
A run down of the tube pins and the voltage on them (at idle), Vdc or Vac as appropriate, starting with the rectifier, is needed also. Pete.

[magnusandmilo]

Thanks for taking a look!
I does overdrive it is just at low output. It sounds great and is got great volume and response if it were a 10watt amp, no sudden jumps etc. Acts like a normal ten watt amp
I do not have the exact power tube voltages with me...I will post them a little later and I was told that the PI and V3B might be off because my meter was loading the circuit.
From memery the output tubes were 325 across on the plate and 11.2V on the cathode 49.5 ohm Cathode. From what I can tell they look great.
The Filters are 337,295,295,235 on the 40uf section of the can but 295 when disconnected?
Heaters are 6.45VAC
I will get more detail later on the rec and power section. I do not have it in front of me right now. Voltages taken with the amp on and off standby with all tubes.
Here are the Voltages For V1-V6
tube v1
pin 1: 174
3: 1.7
6:179
8:1.7

tube v2 (tube in question)
pin1: 286
2:184
3:184
6:183
7:0
8:1.3

tube v3
1:150
3:1.2
6:217
7:9
8:16

tube 4 v4 12at7
1:123
3:2.5
6:124
8:2.5

tube 5
1:100
2:1.4
3:2
6:211
7:13.75
8:21.79

tube 6
1:237
2:42
3:60
6:231
7:40
8:61

All pins left out at 0V or heaters.
Thanks a million!

[pdf64]

Sorry, can you provide the schematic to reference those tubes against? A link or attach a jpg etc. Pete.

[loudthud]

Since the problem seems to affect all channels, you should look at the phase inverter and the output stage. On the long tailed phase inverter, (tube 6 I'm guessing) it's normal to get strange reading on pins 2 and 7, don't be concerned with those.

How confident are you with the connections to the output transformer? Any extra wires that you just grounded? Make sure there are no shorts to ground at any of the speaker jacks.

[magnusandmilo]

I used the webber sch

here is a link to the sch and layout.

sch is attached. i used the 6v30 from webber but with Woden clone transformers so the voltage is a little higher do to 123V coming through the wall.
I will be home shortly to measure other voltages.
Thanks again!

http://taweber.powweb.com/store/6v30_layout.jpg

http://taweber.powweb.com/store/6v30_schem.jpg

[loudthud]

What output tap are you using and what did you do with the unused wires? What speakers have you tried?

[magnusandmilo]

Made it home finally...what a long day at work!
i went ahead and re soldered the output transformer just to see if i found anything and to check connections. As per loudthud...thanks man reading some of your old posts with prior builds really helped me out..
Then .... voltage and started to see if the soldering did anything....nope not really...still low volume...I mean it is loud enough to make you want to turn it down but I am in a 10x10 room. Normal channel is the lowest of all. While tinkering with the controls and a guitar all the sudden the volume dropped and it started the pop, crackle and hiss then came back up to were it was before, minute later drop, pop, and hiss..crackle... Then back up to where is was originally. I assume something must be failing.
Thanks everyone.
Here are the voltages for the other tubes.
Rectifier:
2&8 345VDC to ground, 4&6 308VAC to ground, 608 across, Heaters at 5.3VAC.
Power tubes were all almost identical with 337VDC/336.5 on the Plates (7), 327.5 on the screen grids (9), 11.43 on the Cathode.


I used the 16ohm tap, 8 ohm tap taped up (was going to use an imp selector but lets get it right first)
Grounded the common (to chassis) at the junction going to the sleeve of the speaker jack as per weber layout, 16ohm to the tip. Only three wires on the Woden Clone 8ohm, 16ohm and Common.

My testing speaker is a vintage 30 16ohm. I have also tried my 4x12 16ohm celestion blue cab to rule out cable and speaker.

[magnusandmilo]

Sorry if this is a double I am new to posting
Made it home finally...what a long day at work!
i went ahead and re soldered the output transformer just to see if i found anything and to check connections. As per loudthud...thanks man reading some of your old posts with prior builds really helped me out..
Then .... voltage and started to see if the soldering did anything....nope not really...still low volume...I mean it is loud enough to make you want to turn it down but I am in a 10x10 room. Normal channel is the lowest of all. While tinkering with the controls and a guitar all the sudden the volume dropped and it started the pop, crackle and hiss then came back up to were it was before, minute later drop, pop, and hiss..crackle... Then back up to where is was originally. I assume something must be failing.
Thanks everyone.
Here are the voltages for the other tubes.
Rectifier:
2&8 345VDC to ground, 4&6 308VAC to ground, 608 across, Heaters at 5.3VAC.
Power tubes were all almost identical with 337VDC/336.5 on the Plates (7), 327.5 on the screen grids (9), 11.43 on the Cathode.


I used the 16ohm tap, 8 ohm tap taped up (was going to use an imp selector but lets get it right first)
Grounded the common (to chassis) at the junction going to the sleeve of the speaker jack as per weber layout, 16ohm to the tip. Only three wires on the Woden Clone 8ohm, 16ohm and Common.

My testing speaker is a vintage 30 16ohm. I have also tried my 4x12 16ohm celestion blue cab to rule out cable and speaker.

[magnusandmilo]

Build photos ....problem solved I think...

Thank you thud and everyone for the help. I think I found the problem. The wire coming off the cathode of the pi was weak. i must not have been gentle enough with it. While poking around I got a pop. Replaced the wire and now the pop is gone. Volume seemed to come up a bit and things became more clear. Excellent sounding amp. i still don't know if it is where it should be or not. I need to a/b it with my others but it is plenty loud for me now. I think I will reflow the rest of of joints. Now it is time for a fan. She gets so hot I think she is ready for sex@ I have a small 120vac to 6/12VDC transformer to use. Do you think that would be the way to go?
What do you think of my voltages? Do they seem ok?
Here is a few photos:

[riz]

Well, have you measured it's output? That might tell you a lot.

[magnusandmilo]

Good suggestion. Using the weber calculator I measured watts dissipation at 16 watts per tube but how do I measure output.
I see on a vox site that 25 is typical but how do they get that figure?

[riz]

I'm kinda new at it, but I set up my laptop to produce a sine wave with Audacity to the input, ran the output to an appropriate load resistor, and monitored the output with a scope. Then measure the RMS ac voltage across the load, and convert it to watts. With the scope to guide you, you can measure clean watts, and dimed watts, whatever you want. If you don't have a scope, I suppose you could estimate your clean wattage by hooking a speaker up first and listening, noting where on the volume scale the knob produced the first hints of breakup. So, you're POSITIVE you hooked up the right OT tap, right?

[magnusandmilo]

Tap is correct. Woden clone only has two 8 and 16 at the end. I have been playing out of a lower watt higher gain amp as of late so that might be the difference I am hearing now. After fixing the phase inverter stage things seemed to jump up.
No scope yet trying to find one at a deal. I read that you could use a load resistor 16ohm, crank it, measure the volts using a MM set to mili volts. Square the volt reading and multiply that by the resistance. Do you think that would get me close?
The example they used was: 4ohm load, 10 volt reading so 10x10=100/4=25.
What do you think?

[riz]

If you were going to measure 10v, why would you set your meter to mv?