I was just putting the fet circuit (Normsters layout of cource ) in my clone and I measured the V1 voltages with the other than the dmm that I've been using all the time while building. WHOA! The V1a and V1b voltage differencies were huge !
With MASTECH M-830B (max600VAC) I got 186V and 199V.
With Beckman Industrial DM78 (max450VDC,250VAC) i got 212V and 217V.
Why this kind of difference ? I will borrow tomorrow a FLUKE dmm from my work and measure these voltages again..
I wonder if this causes the slight harshness with higher drive setting on my clone..
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Another thing. I've been trying to figure out the two input jack + the fet circuit wiring but haven't got it yet. I'm using Marshall style isolated jacks.
I studied the Normsters new 6V6 layout but the jacks are dofficult to figure out
mat wrote:
Another thing. I've been trying to figure out the two input jack + the fet circuit wiring but haven't got it yet. I'm using Marshall style isolated jacks.
I studied the Normsters new 6V6 layout but the jacks are dofficult to figure out
Am I very far with the current wiring ?:
Any insight for the two question ?
The problem with this arrangement is that with nothing plugged in anywhere, the V1A input is 1Meg off ground and full of noise. So, your amp will hiss, which I think is "unprofessional."
Here is a simple fix, using a regular jack and an independet break jack. Good luck,
Gil
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My layout uses a "Switchcraft 14B" stereo jack for the FET. In addition to Gil's diagram, study the input jack picture from Gil's #124 photo album. (ODS_124080.jpg) The picture shows pretty clearly how to wire a Cliff-style jack. Between the layout and the picture it should all come together.
Stupid question, but did you measure the voltage with the Mastech before adding the FET? The FET will lower the plate voltage on V1.
mat wrote:Hello,
I was just putting the fet circuit (Normsters layout of cource ) in my clone and I measured the V1 voltages with the other than the dmm that I've been using all the time while building. WHOA! The V1a and V1b voltage differencies were huge !
With MASTECH M-830B (max600VAC) I got 186V and 199V.
With Beckman Industrial DM78 (max450VDC,250VAC) i got 212V and 217V.
Why this kind of difference ? I will borrow tomorrow a FLUKE dmm from my work and measure these voltages again..
Normster, I took quick look for the ODS_124080.jpg and all I got from it was that it has got 7 connectors I hope I can go with by the picture I sent and the stereo jack I have already.
Dogears, the fet was there all the time. I'm little suspicious with the socket I put in tho'. I'll make further measurements tomorrow..
No surprise about Beckmann Fluke being close. You know anyone with a Simpson 60?
In my pro electrical (not electronic) experience, there ain't nothin like a Fluke.
Get a model 87 if you can afford it. Lots of attachments and the very best quality.
My .o2
Dan
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
skyboltone wrote:No surprise about Beckmann Fluke being close. You know anyone with a Simpson 60?
In my pro electrical (not electronic) experience, there ain't nothin like a Fluke.
Get a model 87 if you can afford it. Lots of attachments and the very best quality.
My .o2
Dan
Hi Dan,
Dont know what is the Simpson 60 but I'm definetly going to purchase a FLUKE for sure. I changed the dropping resistor before B+4 from 12k6 to 21k2 and got:
Dont know what is the Simpson 60 but I'm definetly going to purchase a FLUKE for sure. I changed the dropping resistor before B+4 from 12k6 to 21k2 and got:
V1 - 1=193, 6=197
V2 - 1=194, 6=202
B+1=463, B+2=462, B+3=441, B+4=310, B+5=306
, and boy is it cooking now
I'll record something later..
cheers,
FWIW, the Simpson Models 260/261 (I left out the two in the model number) where the Fluke's of their day for electrical measurement. It's a big black all analog meter with 20,000 ohms per volt internal resistance. So if you measure a screen voltage for instance at 420 VDC the meter will impact the circuit like a 8.4 meg resistor. Even a new Fluke disturbs the circuit more than that. Often times a tube will oscillate when measuring plates and screens when a poor quality meter is used.
Good news on your voltages. I'll be looking for the clip!
Dan
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
Good news on your voltages. I'll be looking for the clip!
Dan
Hello Dan. Here is one clip (nothing fancy) BUT it is with the old version, not with the corrected voltages... been busy at work, new clip coming ASAP..
Man I loved that clip, Mat! Even without the tweaks, you're already getting some great tone. But more importantly, dude that clip had some great FEEL!!!
Normster wrote:Man I loved that clip, Mat! Even without the tweaks, you're already getting some great tone. But more importantly, dude that clip had some great FEEL!!!
Thanks Normster I dont consider myself a skilful player (just having fun). Every time I hear my friend play I just plain drool He is that good But every time He listens to my AMP He drools
Would be nice to learn that 'outside' playing dogears and others can do so well...
Hi Mat:
Norm's right. You sound like you're having fun "real good". The amp isn't bad either.
Dan
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
) in my clone and I measured the V1 voltages with the other than the dmm that I've been using all the time while building. WHOA! The V1a and V1b voltage differencies were huge !
But every time He listens to my AMP He drools 
