Yes, they are still available. I will send a message or you can search 'Coleman dht regulators '
Modelling input stage to C-regulator
I have been modelling the input stage just to find out what the effect is of the gyrator section.
The gyrator has less feedback - the output impedance is significantly higher - but it will not in that way try to influence the audio signal on the filament.
Subsequently, it should perform better.
It is for a 10Y preamp by the way.
I have been modelling the input stage just to find out what the effect is of the gyrator section.
The gyrator has less feedback - the output impedance is significantly higher - but it will not in that way try to influence the audio signal on the filament.
Subsequently, it should perform better.
My question is: is my assumption correct? Is the gyrator connection better sounding?
It is for a 10Y preamp by the way.
It's worthwhile to keep the regulator's headroom in mind WRT audio signal level. Beyond the regulator's headroom, isolation is that provided by transformer windings and such. The transition area between the two states is another potential issue, and not something you'd want in the signal path.
The takeaway here is that we don't want more than a tiny amount of signal to appear between regulator and signal ground, but if that is assured, the Coleman regulators or similar are a great improvement for antique valves like you're proposing.
All good fortune,
Chris
yes, I have found a transformer with secondaries that have less than 40pF capacitance to the mains side. That is a very good figure. And it gives 11.1V AC. So I can prereg passively and have a smooth diode action.
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Hi, I am about to start building the PSU's for Coleman filament regs and I would like to repeat a question Andy Evans made long ago and remained - I beleive - without an answer. What is the consensus about using chokes in the PSU?
Rob mentions in his instruction sheet this is something to experiment with (paralleling it to R1).
I have Rob's raw supply PCBs and I am trying to find out if getting the chokes for them or not.
Rob mentions in his instruction sheet this is something to experiment with (paralleling it to R1).
I have Rob's raw supply PCBs and I am trying to find out if getting the chokes for them or not.
Hi Swak
I am using chokes in raw psu for Coleman regulators,it add a silence to sound and full body.
Chokes installed between psu capacitors, resistors in series could be used for voltage trim.
I do like to use chokes as first element of filter, it even better overall for all system since this circuit consumes sinus from power inlet, not spikes in a case of first capacitor filter .
Have to note here, Coleman regulators carry good function of slow current rise and in some cases a first choke can meet zero current event therefore high back voltage spikes occures to shottky diodes and damage them. PSU Designer plots shows this occasion.
There are many way to build such psu safely, though.
I am using chokes in raw psu for Coleman regulators,it add a silence to sound and full body.
Chokes installed between psu capacitors, resistors in series could be used for voltage trim.
I do like to use chokes as first element of filter, it even better overall for all system since this circuit consumes sinus from power inlet, not spikes in a case of first capacitor filter .
Have to note here, Coleman regulators carry good function of slow current rise and in some cases a first choke can meet zero current event therefore high back voltage spikes occures to shottky diodes and damage them. PSU Designer plots shows this occasion.
There are many way to build such psu safely, though.
Hello,
I agree with Alexia. If you didnt buy any parts so yet you better go for a choke input right away! Dave Slagle from intactaudio in the USA even designed a choke input to be used with the Coleman regulators but you can built one yourself.
I prefer using the Lundahl chokes because they are quiet and offer enough mH, the more the better.
You need to use a bleeder resistor so there will be a current running all the time.
What tube are you using? greetings, eduard
I agree with Alexia. If you didnt buy any parts so yet you better go for a choke input right away! Dave Slagle from intactaudio in the USA even designed a choke input to be used with the Coleman regulators but you can built one yourself.
I prefer using the Lundahl chokes because they are quiet and offer enough mH, the more the better.
You need to use a bleeder resistor so there will be a current running all the time.
What tube are you using? greetings, eduard
Attachments
Hi Eduard,
thanks for adding info. Also I could add a note about the Q of filter you get with high choke inductance. There is an impotance of using several tens thousands uF capacitance to aboid voltage hill at the input of regulator at start. Also the high back voltage spikes on diodes occur same time.
I use min 33000uF, usually 3x22000uF and most important solution here is the use resistor in series with choke to press down the Q. With total resistance R+Rchoke=1,5 Ohms and 47mF capacitor the circuit charge time is on par with heating up time of regulator.
thanks for adding info. Also I could add a note about the Q of filter you get with high choke inductance. There is an impotance of using several tens thousands uF capacitance to aboid voltage hill at the input of regulator at start. Also the high back voltage spikes on diodes occur same time.
I use min 33000uF, usually 3x22000uF and most important solution here is the use resistor in series with choke to press down the Q. With total resistance R+Rchoke=1,5 Ohms and 47mF capacitor the circuit charge time is on par with heating up time of regulator.
Hello Russia,
I am using 544 mH input choke in common mode connection. Total DCR is 2*1,7 ohm First cap is 10000 then a small wire wound ( something like 0,5 ohm i forget) then the last 10000. AND a resistor across the first cap to make sure it functions like a choke input even without the load of a tube. If i remember well the voltage on the first cap is 19,5 volt with a tube load for the Rod Coleman circuit. Transformer is 20 volt 2,4 A so it shows the choke input is working. If not the voltage at the first cap would be 25 or more volts.
Greetings, eduard
P.s MOST people will say no need to use the '' load resistor '' but i always do. Can use 25 volt caps and the voltage will rise slowly if there isnt a resistor it will behave as a capacitor input when the tube isnt lit up is my idea
I am using 544 mH input choke in common mode connection. Total DCR is 2*1,7 ohm First cap is 10000 then a small wire wound ( something like 0,5 ohm i forget) then the last 10000. AND a resistor across the first cap to make sure it functions like a choke input even without the load of a tube. If i remember well the voltage on the first cap is 19,5 volt with a tube load for the Rod Coleman circuit. Transformer is 20 volt 2,4 A so it shows the choke input is working. If not the voltage at the first cap would be 25 or more volts.
Greetings, eduard
P.s MOST people will say no need to use the '' load resistor '' but i always do. Can use 25 volt caps and the voltage will rise slowly if there isnt a resistor it will behave as a capacitor input when the tube isnt lit up is my idea
If you built an satisfactorily good raw supply, the other most important thing is using appropriate -critic- parts in R.C regulator instead of usual ones in KIT:
- good non inductive WW resistor as R1 -for example Mills MRA 12-;
- good capacitor in C3 position -for example Amtrans AMCO-.
Mills | Hifi Collective
Amtrans AMCO | Hifi Collective
- good non inductive WW resistor as R1 -for example Mills MRA 12-;
- good capacitor in C3 position -for example Amtrans AMCO-.
Mills | Hifi Collective
Amtrans AMCO | Hifi Collective
Attachments
Thank you, euro21! Some years ago in this tread was discussion about all small resistors.
I use Takman carbon and planning to try Takman metal film, 0,25 W fits regulator board perfect.
Eduard, I noted 1,5 Ohms for LL2733 with parallel connection. In your case with series connection the time constant was far enough for slow warm up of regulator, ok.
I use Takman carbon and planning to try Takman metal film, 0,25 W fits regulator board perfect.
Eduard, I noted 1,5 Ohms for LL2733 with parallel connection. In your case with series connection the time constant was far enough for slow warm up of regulator, ok.
Hello Alexei,
The ll2733 has to winding. Put on the plus side and one in the return. Not1,5 ohm but 2 times 1,7 ohm.greetings, Eduard
The ll2733 has to winding. Put on the plus side and one in the return. Not1,5 ohm but 2 times 1,7 ohm.greetings, Eduard
Thanks all for the input. I am still undecided and will investigate a bit further.
I've got the raw supply boards (+parts) from Rob. I had actually thought of the choke after the cap (Hammond 159ZJ). It seems the input choke would be more expensive (the LL certainly is). What would be the optimal inductance? I am using them with 45, 01a, 4P1L and 300B.
Finally , I've also seen a common mode mode choke being applied, either before CRC (like Intact audio) or after CRC (Moglia).
According to this WW article (Choke or Capacitor Input?) I conclude the cap input might not be bad for this application, but it can pollute the line for for example the DAC, which can be sesitive, but I'm in the process of adapting a battery supply here.
Euro21: thanks for the tip. Would you rate changing both components as equally important, or has the R more impact than the C? I was not aware of those AMCO caps.
I've got the raw supply boards (+parts) from Rob. I had actually thought of the choke after the cap (Hammond 159ZJ). It seems the input choke would be more expensive (the LL certainly is). What would be the optimal inductance? I am using them with 45, 01a, 4P1L and 300B.
Finally , I've also seen a common mode mode choke being applied, either before CRC (like Intact audio) or after CRC (Moglia).
According to this WW article (Choke or Capacitor Input?) I conclude the cap input might not be bad for this application, but it can pollute the line for for example the DAC, which can be sesitive, but I'm in the process of adapting a battery supply here.
Euro21: thanks for the tip. Would you rate changing both components as equally important, or has the R more impact than the C? I was not aware of those AMCO caps.
Using a choke input filter for your raw supply can ease the load seen by your power transformer. That's a great reason to use one! The issue will be voltage loss, which can at least be partially mitigated by using very efficient Schottky diodes.
Audiowize, I still have not bought the power transformer so the voltage loss could be accounted for if going that route.
On the other hand, I could easily spec a higher rating transformer and I believe it would still be much less expensive than using the Lundhal suggested above at the input (I am getting custom wound transformers).
On the other hand, I could easily spec a higher rating transformer and I believe it would still be much less expensive than using the Lundhal suggested above at the input (I am getting custom wound transformers).
Hello All,
I think I'm doing something wrong with my Coleman Regs.
I am building a Type 26 preamp using Rod's regs for the filaments (one per channel). I have been trying to get rid of the hum, and after putting the whole audio circuit in a heavy steel box, I noticed I still had some residual hum. This hum is actually tolerable, and only really noticeable if I stand right at the apex of the room's 60Hz node.
I tried an experiment yesterday that highlighted a problem in my build. I replaced the Coleman Regs with a 4R/10mF RC network to see what would happen.
The hum and most of the tube hiss went completely away! The preamp is far more quiet than it ever has been! The only problem is that without the Regs in place I get a bit of oscillation that manifests as very slight woofer dancing, and an occasional "blocking distortion" -like signal cut-out with an accompanying low frequency noise-- like a "whump." I put the Regs back in, but keeping the additional RC network, and the oscillation is gone but the hum and hiss are back.
Question is: What have done wrong with my Coleman Regs? Or is the rest of the circuit that is causing the trouble?
My Raw Supplies are cLC-cmc-CRC built using:
18v split-bobbin transformers-->Full wave Shottky (two 1N5822)-->1500uF cap-->35mH 2A choke-->22mF ALcap/220uf ALoragnic-->10mH CMC-->10mF ALcap/100nF COG-->5R-->10mF Alcap/220pF COG
This gives me about 18.5V raw/rectified DC.
My Filament Regs were built as per instructions (very thorough PDF) and I get roughly the expected voltage out (about 10.8V). I can adjust current from 800mA up to 1.4A or so. They seem to be working. My leads from Reg to filament are a little less than 250mm tightly twisted 18ga (1mm) solid-core. Heatsinks are adequate. Nothing gets too hot.
Any thoughts?
Best regards,
John
I think I'm doing something wrong with my Coleman Regs.
I am building a Type 26 preamp using Rod's regs for the filaments (one per channel). I have been trying to get rid of the hum, and after putting the whole audio circuit in a heavy steel box, I noticed I still had some residual hum. This hum is actually tolerable, and only really noticeable if I stand right at the apex of the room's 60Hz node.
I tried an experiment yesterday that highlighted a problem in my build. I replaced the Coleman Regs with a 4R/10mF RC network to see what would happen.
The hum and most of the tube hiss went completely away! The preamp is far more quiet than it ever has been! The only problem is that without the Regs in place I get a bit of oscillation that manifests as very slight woofer dancing, and an occasional "blocking distortion" -like signal cut-out with an accompanying low frequency noise-- like a "whump." I put the Regs back in, but keeping the additional RC network, and the oscillation is gone but the hum and hiss are back.
Question is: What have done wrong with my Coleman Regs? Or is the rest of the circuit that is causing the trouble?
My Raw Supplies are cLC-cmc-CRC built using:
18v split-bobbin transformers-->Full wave Shottky (two 1N5822)-->1500uF cap-->35mH 2A choke-->22mF ALcap/220uf ALoragnic-->10mH CMC-->10mF ALcap/100nF COG-->5R-->10mF Alcap/220pF COG
This gives me about 18.5V raw/rectified DC.
My Filament Regs were built as per instructions (very thorough PDF) and I get roughly the expected voltage out (about 10.8V). I can adjust current from 800mA up to 1.4A or so. They seem to be working. My leads from Reg to filament are a little less than 250mm tightly twisted 18ga (1mm) solid-core. Heatsinks are adequate. Nothing gets too hot.
Any thoughts?
Best regards,
John
To help understand the problem, here are the schematics of the Filament Raw PSU and the preamp circuit as it stands.
The preamp is in a temporary state, RC coupled, just to play around with while I wait for the output transformers to arrive.
I certainly hope no one builds the schematic below!!
The preamp is in a temporary state, RC coupled, just to play around with while I wait for the output transformers to arrive.
I certainly hope no one builds the schematic below!!