Dumblelator straight-up, with a twist
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Re: Dumblelator straight-up, with a twist
Hats off to you Martin
awesome looking build
thanks so much for the great layout
Darin
awesome looking build
thanks so much for the great layout
Darin
Re: Dumblelator straight-up, with a twist
Very nice build. In fact..perfect.
My orders to build a Dlator are shipping to me as I write this. One should arrive tomorrow. I ordered a 13.5"X5"X2" enclosure to put it in. I don't think it will be as tight as this, but I expect some challenges.
I went round and round on some of the choices of parts. In my case, keeping costs down while maintaining proper "mojo" was part of the consideration. From what I could make out, it looks like you went with 225P's on the poly caps? Same here.
Where I flaked a little was on the trafos. I was going to get the Tube Depot Button or the Allen, but wasn't sure about the voltages. I had figured out how to get the proper B+ but wasn't sure if the 100K RN65D on the plate of the recovery stage would be correct. So I went with two trafos. One with 140 VAC on the secondary and keeping the voltage doubler and a second 6.3VAC for the heaters.
I would've loved to see this post a few day ago.
I'm drawing plans now. I'm also concerned with noise issues. I think I can maintain good grounding scheme.
"edited to correct voltage"
My orders to build a Dlator are shipping to me as I write this. One should arrive tomorrow. I ordered a 13.5"X5"X2" enclosure to put it in. I don't think it will be as tight as this, but I expect some challenges.
I went round and round on some of the choices of parts. In my case, keeping costs down while maintaining proper "mojo" was part of the consideration. From what I could make out, it looks like you went with 225P's on the poly caps? Same here.
Where I flaked a little was on the trafos. I was going to get the Tube Depot Button or the Allen, but wasn't sure about the voltages. I had figured out how to get the proper B+ but wasn't sure if the 100K RN65D on the plate of the recovery stage would be correct. So I went with two trafos. One with 140 VAC on the secondary and keeping the voltage doubler and a second 6.3VAC for the heaters.
I would've loved to see this post a few day ago.
I'm drawing plans now. I'm also concerned with noise issues. I think I can maintain good grounding scheme.
"edited to correct voltage"
Last edited by SoundPerf on Wed Jun 29, 2011 2:10 am, edited 4 times in total.
Chris
- martin manning
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Re: Dumblelator straight-up, with a twist
Hey, thanks Darin, and you're welcome.
SoundPerf, thanks; it's not nearly perfect... I know where all the flaws are, and I've hidden them well! Yes. 225P's, 400V except the 0.47 is 200V. I'm sure your two PT set-up will work fine, and from what I could tell the sound was very good running 30V low, so it's not too critical. You'd want to keep the 100k for the plate load even if your B+ is a bit higher or lower than spec; that stage wants to be center-biased and up in the linear part of the plate curves.
SoundPerf, thanks; it's not nearly perfect... I know where all the flaws are, and I've hidden them well! Yes. 225P's, 400V except the 0.47 is 200V. I'm sure your two PT set-up will work fine, and from what I could tell the sound was very good running 30V low, so it's not too critical. You'd want to keep the 100k for the plate load even if your B+ is a bit higher or lower than spec; that stage wants to be center-biased and up in the linear part of the plate curves.
- David Root
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Re: Dumblelator straight-up, with a twist
I've done Normster's buffered loop built in to the head amp twice, and it sounds good. I like it with a 12AT7 rather than a 12AX7.
Yes it's a truncated design compared with the Full Monty. Are there any of you have done it both ways and could comment as to tone/feel of both?
Yes it's a truncated design compared with the Full Monty. Are there any of you have done it both ways and could comment as to tone/feel of both?
Re: Dumblelator straight-up, with a twist
That's what I figured was the case. I kept checking everyones builds and they all kept that the same. I figure since the original went to the trouble to use such precision resistor there, it must be important. Thanks for the heads up.martin manning wrote: You'd want to keep the 100k for the plate load even if your B+ is a bit higher or lower than spec; that stage wants to be center-biased and up in the linear part of the plate curves.
Chris
Re: Dumblelator straight-up, with a twist
Make sure the cathode voltage on the cathode follower is right around 30v for best performance.
You can adjust the 27K tail to adjust that if needed.
But if I recall, I adjusted the dropping string to achieve the voltages I wanted.
You can adjust the 27K tail to adjust that if needed.
But if I recall, I adjusted the dropping string to achieve the voltages I wanted.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Dumblelator straight-up, with a twist
I've been using this Java based Analog Circuit Sim to do my calculations. Available here. http://www.falstad.com/mathphysics.htmlStructo wrote:Make sure the cathode voltage on the cathode follower is right around 30v for best performance.
You can adjust the 27K tail to adjust that if needed.
But if I recall, I adjusted the dropping string to achieve the voltages I wanted.
It seems pretty accurate. Although with my 3.0Ghz dual core system, a Dlator size circuit starts to process pretty slowly.
Anyway, right now I'm showing ~28V on the cathode. If I raise the 27k to 30K I get 30V exactly. I have 259V on the plate of the input stage. It will be interesting to see what the real world results will be.
Chris
Re: Dumblelator straight-up, with a twist
Sounds good!
Geez, I would think a 3 GHz Dual Core would run any sim pretty fast.
Of course you have to have at least 2GB of RAM if not 4.
Geez, I would think a 3 GHz Dual Core would run any sim pretty fast.
Of course you have to have at least 2GB of RAM if not 4.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Dumblelator straight-up, with a twist
I have 4GB. It runs Ok, it just takes a little bit for voltages to adjust after changes. I do have the full dlator circuit running though. I also have Win7 64bit. With 64bit Java. I think I've seen performance issues with older Java programs.Structo wrote:Sounds good!
Geez, I would think a 3 GHz Dual Core would run any sim pretty fast.
Of course you have to have at least 2GB of RAM if not 4.
Thanks for the info, BTW.
Chris
Re: Dumblelator straight-up, with a twist
I built a loop using the Allen transformer.
It fits inside a 1 space rack.
I built it using the power supply board in Martin Mannings drawing.
That drawing is in the second post in this thread.
I ordered 2 transformers to meet the $50 minimum.
Now that I have 2 amps I might as well have 2 loops.
Good luck.
It fits inside a 1 space rack.
I built it using the power supply board in Martin Mannings drawing.
That drawing is in the second post in this thread.
I ordered 2 transformers to meet the $50 minimum.
Now that I have 2 amps I might as well have 2 loops.
Good luck.
Dumbleator help...
Hi!
I built a MP Manning dumbleator.
It works BUT there is a big hum, as loud as the signal of the preamp!
I respected all the grounding
All the voltages are good
Shielded signal wires
When I switch off the unit, it works perfectly during 15sec... because of the psu capacitors.
I tried to put the power xformer out of the case, same deal...
There is something I don't understand...
I built a MP Manning dumbleator.
It works BUT there is a big hum, as loud as the signal of the preamp!
I respected all the grounding
All the voltages are good
Shielded signal wires
When I switch off the unit, it works perfectly during 15sec... because of the psu capacitors.
I tried to put the power xformer out of the case, same deal...
There is something I don't understand...
- martin manning
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Re: Dumblelator straight-up, with a twist
Is the hum 60 Hz or 120 Hz (or 50 or 100 if you are in one of those zones) ? This will tell you whether the hum is from the AC heater circuit (center tap not grounded for example) or from the HV rectifier.
Re: Dumblelator straight-up, with a twist
It is a 50hz hum circuit...martin manning wrote:Is the hum 60 Hz or 120 Hz (or 50 or 100 if you are in one of those zones) ? This will tell you whether the hum is from the AC heater circuit (center tap not grounded for example) or from the HV rectifier.
The toroidal has:
6.3v with no center tapped
12.6 with no center tapped
do I need a center tapped for heaters?
- martin manning
- Posts: 13242
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Dumblelator straight-up, with a twist
Yes. Connect a 100-ohm resistor from each leg of the heater winding you are using to ground to create a virtual center tap.
Re: Dumblelator straight-up, with a twist
It works if I connect pin 9 to ground... but is it safe? do I have to add a 1ohm resistor between pin 9 and ground?martin manning wrote:Yes. Connect a 100-ohm resistor from each leg of the heater winding you are using to ground to create a virtual center tap.
I'm gonna try your solution too!
Thanks for your help!!!!
will post some pics...