The first choke for the 300B should be low in DCR because it takes more than 80mA each channel. I had used one Hammond 10H 300mA for my stereo 45 tube amp which only takes approximately 70mA in total.
In fact, I would use double choke filtering for the 300B to keep the B+ ripple minimal. Also, it is nice to control B+ by adjusting the value of the first input capacitor.
Johnny
In fact, I would use double choke filtering for the 300B to keep the B+ ripple minimal. Also, it is nice to control B+ by adjusting the value of the first input capacitor.
Johnny
Do you think the hammond 374bx could be a good choice for these monoblocks ? It should not be so difficult to get the 10 V missing playing with the rectifier choice and first capacitor.
Do you know what's the secondary resistance of this power transformer ?
Best Regards,
Davide
Do you know what's the secondary resistance of this power transformer ?
Best Regards,
Davide
I think it would be fine for a monoblock. I am not sure about the secondary resistances (I have never really concerned myself with these to be honest).
I am using the Edcor XPWR134 which is similar, 375-0-375 @200mA x2 6.3v and one 5v. I think 5v difference is negligible (<10%) considering variations in line voltage. In fact, I have done just what you have proposed by increasing my 1st cap value to 50uF from 47uF. Everything comes in real close to spec when I model it on PSUD2.
FYI (I just learned this and you may already be aware) the ASC oil filter caps (motor run) at Allied Electronics rated at 440VAC ($15 50uF) are more than enough for a 600V application for DC filtering. The design called for a 500+V rated filter cap and at first I was thinking these ASC's at Allied would not work. I was also wondering where Angela sourced their 600V ASC's ($20 50uF) from. Turns out the 440V rating is for AC not DC......apparently you can use the 1.4x conversion factor for caps too when calculating specs. So a 440VAC will easily handle up to 616VDC. Anyway, you can save $5 a cap by ordering basically the same cap (Angela's 50uF 600V) from Allied.
The only thing I am missing at this point in sourcing my parts is a good high quality 24K 2W resistor. I have used Caddocks 935 series for the 1K and 68K resistors in the circuit so far but can't seem to find a similar 24K resistor. Anybody know where I can find a 24K Caddock?
Thanks,
Jeff
The Angela PT is still available
Why the fuss over cloning the Angela power tranformer? It's still available. See the link below.
Angela Instruments Online Catalog - Transformers - Angela Universal Power Transformers
I have used the Angela Universal for two sets of monoblocks, so 4 units altogether, and I am very pleased. All the units run remarkably cool and have virtually no hum or buzz. A clone transformer MIGHT have the same voltages and run as cool and quietly, but why take a chance when you can get the original?
Dave
Why the fuss over cloning the Angela power tranformer? It's still available. See the link below.
Angela Instruments Online Catalog - Transformers - Angela Universal Power Transformers
I have used the Angela Universal for two sets of monoblocks, so 4 units altogether, and I am very pleased. All the units run remarkably cool and have virtually no hum or buzz. A clone transformer MIGHT have the same voltages and run as cool and quietly, but why take a chance when you can get the original?
Dave
No fuss really....I just love Edcor. I like their service, their products, their colors, and their prices. I am willing to take a risk that not only will they get everything right but that it will be a superior result. I have used Edcor for the past 2 years now without a hitch. The real question I have though is not about their power transformer but their CXSE OPT for the 300B circuit. I used the CXSE for the KT88SE project I just finished and got exceptional results. I cannot decide between the Edcor and James OPTs at the moment. I might just have to take a leap of faith. I might just initially mount the OPTs off the monoblock for a trial, if all works well then mount them up.....if less than satisfactory results I will sub the James 6123HS.
Jeff
Jeff
Changing my mind
This is a bit off topic but not really....I was in the process of sourcing parts for the Hagtech Clairion 2A3 SE amplifier when I realized the amp requires a preamp as it is just designed for a 4v to drive to clipping, basically only a driver stage before the 2A3. I really wanted to build an all-in-one 2A3 amp(integrated) So now I am considering building the JEL 2A3 DX stereo. I have the 6SN7 and 76/56/27 preamp tubes so no problem there. Where my problem is is I have already on hand (purchased) all the parts for the Hagtech design. This necessitates the use of these parts and a re-design of the original power supply.
I wanted some input here by some more advanced builders than I....I realize that the power supply is the heart of the amp so when you go mucking with this you can really change the amp.
The original Hagtech used an LCLC x2 RC (split rail) with a 700VCT Hammond. The JEL calls for a 640VCT and a much simpler CLC x2RC filter.
I am modeling a CLCLC x2RC as such....5uF(variable for final B+ of 355v) then a 5H then 200uF then 1H then 100uF the the split rails with a 1.2k and 45uF cap for the pre/drivers. If I fiddle with these values I can get very close to the B1+ of 355v and B2+ of 350v.
I have a few questions.....first, what is the downfall of using the CLCLC? The original had the rectifier going straight into the first choke.
Second, can anybody tell me the current draw of the 2A3 and the 76 and 6SN7 tubes in the JEL SE2A3dx here:SE300B classic and DX (about the 4th schematic down or so).
I am not to sure where to model the current on PSUD2 for this power supply I am proposing.
Also, the JEL calls for an 200mA choke and mine is a 150mA, will this bee too much of a problem since the max current could be right at 150mA? (assuming the maximum current of all tubes in the circuit based on the tube specs)
I could use just the 5H in a CLC x2 RC like the original JEL but the addition of the second choke really gets the ripple and voltage to where I want it. The Hagtech uses this dual choke design and supposedly with excellent results.
The other thing I like about the JEL over the Hagtech model is the ability to drop in 45 tube which I have several now (literally bought 8 in the past 2 hours).
Please give me some insight into the use of 2 chokes like this and all the drawbacks in using a power supply like this over the original.
Last question, the 5 pin sockets for the 76 type tubes, where is the best source in the US to get these? I need a couple now.
Thanks alot everyone,
Jeff
This is a bit off topic but not really....I was in the process of sourcing parts for the Hagtech Clairion 2A3 SE amplifier when I realized the amp requires a preamp as it is just designed for a 4v to drive to clipping, basically only a driver stage before the 2A3. I really wanted to build an all-in-one 2A3 amp(integrated) So now I am considering building the JEL 2A3 DX stereo. I have the 6SN7 and 76/56/27 preamp tubes so no problem there. Where my problem is is I have already on hand (purchased) all the parts for the Hagtech design. This necessitates the use of these parts and a re-design of the original power supply.
I wanted some input here by some more advanced builders than I....I realize that the power supply is the heart of the amp so when you go mucking with this you can really change the amp.
The original Hagtech used an LCLC x2 RC (split rail) with a 700VCT Hammond. The JEL calls for a 640VCT and a much simpler CLC x2RC filter.
I am modeling a CLCLC x2RC as such....5uF(variable for final B+ of 355v) then a 5H then 200uF then 1H then 100uF the the split rails with a 1.2k and 45uF cap for the pre/drivers. If I fiddle with these values I can get very close to the B1+ of 355v and B2+ of 350v.
I have a few questions.....first, what is the downfall of using the CLCLC? The original had the rectifier going straight into the first choke.
Second, can anybody tell me the current draw of the 2A3 and the 76 and 6SN7 tubes in the JEL SE2A3dx here:SE300B classic and DX (about the 4th schematic down or so).
I am not to sure where to model the current on PSUD2 for this power supply I am proposing.
Also, the JEL calls for an 200mA choke and mine is a 150mA, will this bee too much of a problem since the max current could be right at 150mA? (assuming the maximum current of all tubes in the circuit based on the tube specs)
I could use just the 5H in a CLC x2 RC like the original JEL but the addition of the second choke really gets the ripple and voltage to where I want it. The Hagtech uses this dual choke design and supposedly with excellent results.
The other thing I like about the JEL over the Hagtech model is the ability to drop in 45 tube which I have several now (literally bought 8 in the past 2 hours).
Please give me some insight into the use of 2 chokes like this and all the drawbacks in using a power supply like this over the original.
Last question, the 5 pin sockets for the 76 type tubes, where is the best source in the US to get these? I need a couple now.
Thanks alot everyone,
Jeff
Angela clone from Edcor
Hi, I finally received a reply from Phyllis at Edcor, this is a cut and paste from her email back to me:
"On the power transformer it would have to be a custom unit.
Primary: 120/240 50/60 Hz
Secondary: 760 volt (380-320-0-320-380) @ 200mA,
6.3 volt (3.15-0-3.15) @ 3.5A
5 volt @ 3A
Would cost $61.89 each plus a one time design cost of $40.00."
So, after I have paid the one time fee of $40 it will be available to everyone else for $61.89. That is basically 2 for the price of one at Angela.
I have asked Phyllis to provide me with the ordering code for this transformer, it will be XPWR followed by a 3-4 digit number. When she gets it to me I will post it here. Their turnaround time is 3-4 weeks on transformers as they wind each one as they are ordered. This is the one drawback I have found with Edcor, the wait. Otherwise you can't beat their prices and quality. Their service is superb too, Phyllis is very helpful with inquiries and suggestions.
Have a nice day,
Jeff
Hi, I finally received a reply from Phyllis at Edcor, this is a cut and paste from her email back to me:
"On the power transformer it would have to be a custom unit.
Primary: 120/240 50/60 Hz
Secondary: 760 volt (380-320-0-320-380) @ 200mA,
6.3 volt (3.15-0-3.15) @ 3.5A
5 volt @ 3A
Would cost $61.89 each plus a one time design cost of $40.00."
So, after I have paid the one time fee of $40 it will be available to everyone else for $61.89. That is basically 2 for the price of one at Angela.
I have asked Phyllis to provide me with the ordering code for this transformer, it will be XPWR followed by a 3-4 digit number. When she gets it to me I will post it here. Their turnaround time is 3-4 weeks on transformers as they wind each one as they are ordered. This is the one drawback I have found with Edcor, the wait. Otherwise you can't beat their prices and quality. Their service is superb too, Phyllis is very helpful with inquiries and suggestions.
Have a nice day,
Jeff
I should mention one thing....this is not an exact clone as I did not have them add the additional 5v 1.5A secondary. I did not want this. I use a separate 5VCT transformer per filament on the 300B so a balanced arrangement can be used with the centertap.
The extra 5VCT transformer is about $20 at AES. This keeps the main transformer running cooler. I think this is even recommended at the JEL website, to use a separate filament transformer for the power tubes.
Other than that this transformer should work just fine for the JEL/Walton 300B and 2A3, as well as the 45 and 205 amps.
Jeff
The extra 5VCT transformer is about $20 at AES. This keeps the main transformer running cooler. I think this is even recommended at the JEL website, to use a separate filament transformer for the power tubes.
Other than that this transformer should work just fine for the JEL/Walton 300B and 2A3, as well as the 45 and 205 amps.
Jeff
Is the Edcor shielded? The Angela is, and depending on what you have in your home (dimmers, drives), it makes a big difference.
Not sure what you mean by "shielded". It has steel endbells like Angela's. It has exposed laminations like Angela's. I am not exactly sure what they are referring to when they claim their's is "shielded". It would be interesting to know what they have done to their transformer to cause it to be "shielded".
I will ask Both Edcor and Angela about shielding.
Jeff
Angela Clone
I should probably quit referring to this as a "Clone" because it really is not. I just had Edcor design a transformer that would give me what I wanted....the same operating points for building the 45, 205, 2A3, and 300B amps on JEL's website. I should also mention that I did not ask for a 55v bias tap as these are not needed in any of the designs I am planning to build. So if you want an Angela Universal Power transformer, exactly like theirs, this is not the transformer for you. If you want a great low cost alternative that will work to build these amps I think this will be a good solution.
I have put 2 email requests, one to Edcor and one to Angela, to explain the shielding they do or don't use. I will post their responses as soon as I hear back from them.
Jeff
I should probably quit referring to this as a "Clone" because it really is not. I just had Edcor design a transformer that would give me what I wanted....the same operating points for building the 45, 205, 2A3, and 300B amps on JEL's website. I should also mention that I did not ask for a 55v bias tap as these are not needed in any of the designs I am planning to build. So if you want an Angela Universal Power transformer, exactly like theirs, this is not the transformer for you. If you want a great low cost alternative that will work to build these amps I think this will be a good solution.
I have put 2 email requests, one to Edcor and one to Angela, to explain the shielding they do or don't use. I will post their responses as soon as I hear back from them.
Jeff
Shielding means there is a copper or aluminum foil wound in between the primary winding and secondary windings. It guards (shields) the capacitance between the windings, so that common mode noise present on the AC line cannot be coupled into any of the secondary windings. Since the shield is grounded, noise is shunted to ground, and cannot reach the secondaries.
Regardless whether one desires a shield or values it is independent of the fact that one transformer is shielded, and the other is not. This is a difference, and would affect the price of the end product. I for one will no longer buy power transformers for my audio equipment unless it is either a) shielded or b) split bobbin.
If this is important to you, it might be worthwhile to tweak the design (it is custom, after all) and request this be added. Price quoted does seem very reasonable.
Regardless whether one desires a shield or values it is independent of the fact that one transformer is shielded, and the other is not. This is a difference, and would affect the price of the end product. I for one will no longer buy power transformers for my audio equipment unless it is either a) shielded or b) split bobbin.
If this is important to you, it might be worthwhile to tweak the design (it is custom, after all) and request this be added. Price quoted does seem very reasonable.
Power Transformer Shielding
Do you know of which companies besides Angela that provide shielding or split bobbin use on their power transformers? I have not really paid much attention to this technology nor seen it advertised (except now I see it at Angela's website). Does Hammond use any of these techniques in their transformers? I use an IEC filter jack for my power inputs. I am wondering if this provides the same level of common mode noise reduction as the shielding or split bobbin.
Jeff
Do you know of which companies besides Angela that provide shielding or split bobbin use on their power transformers? I have not really paid much attention to this technology nor seen it advertised (except now I see it at Angela's website). Does Hammond use any of these techniques in their transformers? I use an IEC filter jack for my power inputs. I am wondering if this provides the same level of common mode noise reduction as the shielding or split bobbin.
Jeff
I found this at Electra-print's website:
"An electrostatic shield between primary and first secondary, is to keep the device the transformer is operating from interfering with the power line, not to shield the device from the power line. This shield will not make the power supply hum any less than the filter design used. It also will decrease the efficiency of the transformer and increase heat rise."
Here:Electra-Print.com Custom Power Transformers
Jeff
"An electrostatic shield between primary and first secondary, is to keep the device the transformer is operating from interfering with the power line, not to shield the device from the power line. This shield will not make the power supply hum any less than the filter design used. It also will decrease the efficiency of the transformer and increase heat rise."
Here:Electra-Print.com Custom Power Transformers
Jeff
Hi Jeff, the Walton MkII 300B and JEL 300B DX schematics are identical! They only differ in the PSU values.
What choke values is Edcor making?... Are you going to have two 8H chokes or one 15H or 20H choke in the JEL 300B DX?...
I just wanted to tell you that I am committed to buying (2) Edcor custom transformers (similar to the Angela specs) for the Walton 300B amps. If any of the chokes are the same, then also I'll buy the chokes too.
If my SE KT88, turns out well, then I'll also get another pair of James 6123HS OPT.
Thanks
What choke values is Edcor making?... Are you going to have two 8H chokes or one 15H or 20H choke in the JEL 300B DX?...
I just wanted to tell you that I am committed to buying (2) Edcor custom transformers (similar to the Angela specs) for the Walton 300B amps. If any of the chokes are the same, then also I'll buy the chokes too.
If my SE KT88, turns out well, then I'll also get another pair of James 6123HS OPT.
Thanks
I might have missed it, but are you using this power transformer for both channels or using two?
Well, I don't agree with Electraprint's statement. A shield will reduce noise in both directions, and hum has absolutely nothing to do with the subject. We are talking about high frequency noise, hash, RF, etc. The basic premise is there is a guarding shield between the primary winding and secondary winding.
Maybe this link helps:
The engineering handbook - Google Books
I have a drive in my home that runs the well pump. A shielded transformer did wonders to completely kill the switching noise in the audio equipment. Noise on one side, not the other. Direction is irrelevant when the shield is designed right.
Maybe this link helps:
The engineering handbook - Google Books
I have a drive in my home that runs the well pump. A shielded transformer did wonders to completely kill the switching noise in the audio equipment. Noise on one side, not the other. Direction is irrelevant when the shield is designed right.
Zigzagflux,
That is a very good article. It makees sense to me. I am wondering if by making those statements Jack at Electrprint is meaning to say that he does not shield his transformers. I am almost afraid to ask him after reading the other comments he makes about other points he has strong feelings about.
I am wondering though if the use of a simple $5 IEC socket filter will give the same results with RF, and other high frequency or common mode noise.
It appears that some of Tyco's products that range from $7 to $15 will provide upto 65dB of CM noise reduction, the specific model I am using appears to provide up to 47dB.
I have put a request to Edcor to specifically answer this question though and should have it within a couple of days. Either they do this on all their transformer or they don't I will bet. If they don't I will also bet they probably won't offer this as a custom upgrade. Just my premonition.
As far as chokes go, I have asked them to give me a price on this before I commit to having them produce them. Seems that Hammond and Triad already make a low cost coke for both these applications there is no use for me to spend a whole bunch extra for the design fees.
Mouser carries a 10H 90mA inductor I plan to use in the second position if Edcor ends up being more than I want to spend. The cost at Mouser is $11, pretty tough to beat.
I plan to use the Hammond 10H 125mA in the first position.
Thanks,
Jeff
That is a very good article. It makees sense to me. I am wondering if by making those statements Jack at Electrprint is meaning to say that he does not shield his transformers. I am almost afraid to ask him after reading the other comments he makes about other points he has strong feelings about.
I am wondering though if the use of a simple $5 IEC socket filter will give the same results with RF, and other high frequency or common mode noise.
It appears that some of Tyco's products that range from $7 to $15 will provide upto 65dB of CM noise reduction, the specific model I am using appears to provide up to 47dB.
I have put a request to Edcor to specifically answer this question though and should have it within a couple of days. Either they do this on all their transformer or they don't I will bet. If they don't I will also bet they probably won't offer this as a custom upgrade. Just my premonition.
As far as chokes go, I have asked them to give me a price on this before I commit to having them produce them. Seems that Hammond and Triad already make a low cost coke for both these applications there is no use for me to spend a whole bunch extra for the design fees.
Mouser carries a 10H 90mA inductor I plan to use in the second position if Edcor ends up being more than I want to spend. The cost at Mouser is $11, pretty tough to beat.
I plan to use the Hammond 10H 125mA in the first position.
Thanks,
Jeff
For the record, my 300B PP monoblocks use (4) Electraprint power transformers. They are fantastic, quality-built units, and though you will pay more than a comparable Edcor, they are a good option. Being that they were custom builds, I requested a shield, and Jack graciously provided one. So, it's not that I discourage using his products, I simply disagree with his statement about shield application. I see no reason why any custom xfmr builder could not provide a shield for just a few bucks extra.
The IEC input filter will remove some noise, but I would say both the magnitude and frequency range of the attenuation will be greater with the shielded transformer. If you don't have major problems with noise (as measured with an oscilloscope, not your ears) now, there may be no need for the shield, and the input filter may be just fine.
Consider Angela Instruments Online Catalog - Home for your Hammond products. They are consistently the lowest price around; not sure why this is.
The IEC input filter will remove some noise, but I would say both the magnitude and frequency range of the attenuation will be greater with the shielded transformer. If you don't have major problems with noise (as measured with an oscilloscope, not your ears) now, there may be no need for the shield, and the input filter may be just fine.
Consider Angela Instruments Online Catalog - Home for your Hammond products. They are consistently the lowest price around; not sure why this is.
Either/or
Can be used for one or two depending on which you are building. There are the monoblocks and stereo versions both posted here:
SE300B classic and DX
Personally I am building the monoblocks so I will be using one per channel.
Can be used for one or two depending on which you are building. There are the monoblocks and stereo versions both posted here:
SE300B classic and DX
Personally I am building the monoblocks so I will be using one per channel.
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