Yes with my aging eyes and not constant exposure to color codes, I always stick a meter on my resistors.
Not only to verify that they are what the code says but to make sure it is within tolerance of the stated value.
I meter them, then tape them to a piece of heavy stock paper with the measured value written beside them.
Takes a bit longer to do it this way but then I am assured that what I solder into the amp is the right part.
Alright now, I've now made from what I can tell is another baaad error. I went with the BOM on the files page and it has 47 at 250v caps (6)in the power supply and I combined 47 @ 350(2) the subsequently 47 @ 250 (6)for the rest. Yes, I admit this freely as the truth will set you, well you know. Anyway I'm now waiting for a Mouser order made and will continue rebuilding what I knew was a really weird power section. That V2a plate- before I realized this had a lower voltage of 235v and but the other side was 184v. V1a was 192 and b 184 the PI was a310 and b 302. So I know once this gets straightend out the voltages should be pretty much in there. I know tweaking the HRM module in will take time as well. Anyway, there it is bad eyes and judgement to boot whoooo! .
Rev.07/27/08-I now see the same power supply in the Resophonic gooped picts newly unveiled. I don't feel so bad now.
Ok, the amp is working and the cleans are nice, but I tell you I pop into OD and the gain is minimal. I followed the schem from HiGain w/ the 25k OD trimmer so I don't know if this is normal or not but I wouldn't even call it medium gain at this point.
Anyways, the voltages settled to:
V1a194 b.185
V2a215 b.207
V3a316 b.303
Plates on Power tubes are 440v and bias@35mA
It's pretty quiet as far as tube amps go.
So I'm off to tweak this and am already reading Gils trials and tribulations to see where to go next. I'll update the pics in the beginning for anyone venturing this direction.
Thanks all for your help and patience, again, I've learned a ton from this build and you guys.
moj067 wrote:Ok, the amp is working and the cleans are nice, but I tell you I pop into OD and the gain is minimal. I followed the schem from HiGain w/ the 25k OD trimmer so I don't know if this is normal or not but I wouldn't even call it medium gain at this point.
Anyways, the voltages settled to:
V1a194 b.185
V2a215 b.207
V3a316 b.303
Plates on Power tubes are 440v and bias@35mA
It's pretty quiet as far as tube amps go.
So I'm off to tweak this and am already reading Gils trials and tribulations to see where to go next. I'll update the pics in the beginning for anyone venturing this direction.
Thanks all for your help and patience, again, I've learned a ton from this build and you guys.
Are you enabling the PAB when you go into overdrive. If not, there is not that much gain.
Located in the St Croix River Valley- Afton, MN
About 5 miles south of I-94
aka K0GWA, K0 Glas Werks Amplification www.glaswerks.com
New improved version up and functional PAB seems to elude me for now.
Forgive the messy wiring as I will not tie anything down until everything is stable and functional to my satisfaction, which should be maybe next year at this rate .
dogears wrote:Also make sure you have the 150K grid resistor on OD2.
Let us know!
Hi, Scott,
The D'Lite has a 180k in this spot. From what I can tell of the circuit, lowering this resistor to 150k would be akin to just turning up the Drive pot 30k. What am I missing, or is this just an HRM change?
It is a change to the HRM to compenstate for the 250K pot. If you look backwards from the V2b grid, you can see that changing the grid resistor has a big effect on Miller Effect with no change in gain. If you dial in the drive pot to get the same load, you change the gain divider.....
It is only on the EL34 HRM amps to the best of my knowledge. All Bluesmasters I have seen have 180K. ALo, the couple 6L6 HRM hybrid amps had 180K as well.
greiswig wrote:
dogears wrote:Also make sure you have the 150K grid resistor on OD2.
Let us know!
Hi, Scott,
The D'Lite has a 180k in this spot. From what I can tell of the circuit, lowering this resistor to 150k would be akin to just turning up the Drive pot 30k. What am I missing, or is this just an HRM change?
dogears wrote:It is a change to the HRM to compenstate for the 250K pot. If you look backwards from the V2b grid, you can see that changing the grid resistor has a big effect on Miller Effect with no change in gain. If you dial in the drive pot to get the same load, you change the gain divider.....
It is only on the EL34 HRM amps to the best of my knowledge. All Bluesmasters I have seen have 180K. ALo, the couple 6L6 HRM hybrid amps had 180K as well.
Great explanation. That's what I needed! Thanks as usual.
We now return you to your regularly scheduled unhijacked thread.
I've got to try that because I've got to to really crank the drive pot to get any appreciable sustainy gain. I know what is meant by this amp is appreciated at louder than usual practice volume It's like the pre- section waits for the power section to catch up. When turning the drive up it's sorts, sorta ,sorta then whomp! I do like it's throaty purr, just doesn't show up soon enough for me. I'll let you know how the 150k works.
The Dumble that I played, that was similar to your build, required 1 to 2 oclock on the OD gain pot...... It is not unusual to be past noon a bit. But before 3 oclock for me.
moj067 wrote:I've got to try that because I've got to to really crank the drive pot to get any appreciable sustainy gain. I know what is meant by this amp is appreciated at louder than usual practice volume It's like the pre- section waits for the power section to catch up. When turning the drive up it's sorts, sorta ,sorta then whomp! I do like it's throaty purr, just doesn't show up soon enough for me. I'll let you know how the 150k works.
Well, when Dogears says "try you'll like it" listen to the man.
150k on V2a. did the trick exactly as advertised and is the way to go w/ this HRM as far as gain goes. I've got to dial in the HRM module in some though, it's a little too fat right now. Drive @ around 2 o'clock was just right w/ OD vol at 9 or 10 o'clock. I think I can get it to sustain notes better w/the Dlator.
Right now w/ no effects the distortion is a little dry and stiff, the cleans are great though-that is the biggest surprise to me right now. I gonna let it burn in some w/ a Shefffied burn-in disk and play some more Sun.
Thanks again Funk for leading the blind and everyone else to birthing another one of these.
Did you try my stack settings? Try the pre-OD gain trimmer set at 24K from ground. Make sure you have a 1uf on OD2. You should not be too fat with PAB on. Don't set the mids too high on the HRM. Anything over 10K to 11K is too much IMO. Treble should be almost 50% up.
moj067 wrote:Well, when Dogears says "try you'll like it" listen to the man.
150k on V2a. did the trick exactly as advertised and is the way to go w/ this HRM as far as gain goes. I've got to dial in the HRM module in some though, it's a little too fat right now. Drive @ around 2 o'clock was just right w/ OD vol at 9 or 10 o'clock. I think I can get it to sustain notes better w/the Dlator.
Right now w/ no effects the distortion is a little dry and stiff, the cleans are great though-that is the biggest surprise to me right now. I gonna let it burn in some w/ a Shefffied burn-in disk and play some more Sun.
Thanks again Funk for leading the blind and everyone else to birthing another one of these.
looking at the pics I see a potential issue with the shielded cable that could cause many of the problems you describe, it has a conductive black jacket over the center clear insulation (not the shrink sleeve). You must double strip that cable so that the black jacket does not touch the hot conductor or you will have added resistance going to ground like around 2K~5K, that internal black jacket is very conductive it is an extra shield and I see many places where it looks like it could be touching the hot connection, this is not enough resistance to shut the amp down just to load the circuits and make you loose gain and high end. You should not have that black jacket near the tip(center) you should only see the clear insulation 1/8" from the end.
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