If you go with a bigger wattage OT like the Valve Transformer VT 1545, and plan to use it that way eventually, you may want to also use a lower primary Z to fit better with the bigger output tubes (without having to go to higher B+ and all new caps etc).
At 50 Watt output, you might want around a 4 or 5 K Ohm primary OT. At 75 watt, around a 3.3K Ohm primary. The 6JN6s will run fine with a 4 or 5K Ohm primary as well.
There are some other tubes that can be fitted to the design easily. The 21JV6 fits the same socket, but would need a separate 21 V heater supply. It would handle 50 Watts out.
With a rewiring of the sockets, the 6HJ5 will handle 75 Watts out. (even 100 Watts, see the original thread for info on using the 6HJ5.) These popular tubes are available in quantity again at Vacuumtubes.net for $4.
At 50 Watt output, you might want around a 4 or 5 K Ohm primary OT. At 75 watt, around a 3.3K Ohm primary. The 6JN6s will run fine with a 4 or 5K Ohm primary as well.
There are some other tubes that can be fitted to the design easily. The 21JV6 fits the same socket, but would need a separate 21 V heater supply. It would handle 50 Watts out.
With a rewiring of the sockets, the 6HJ5 will handle 75 Watts out. (even 100 Watts, see the original thread for info on using the 6HJ5.) These popular tubes are available in quantity again at Vacuumtubes.net for $4.
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I may want to upgrade the amp at some point but to start with i would like to keep it original. Some think tubelab said in the original thread. Being a newbie its better to make the original design as close as possible, make sure it works then start changing things one at a time and analyse the change.
so i would like OT as close to spec as possible, or at least ones that others have tried and know they work well. I would like to stick to the original valves but it may be a problem getting then in the UK
So far i have three choises the original Edcor from euros, the troidals (but as already said these may be a problem with the balancing) and then the OT from the previous post.
so i would like OT as close to spec as possible, or at least ones that others have tried and know they work well. I would like to stick to the original valves but it may be a problem getting then in the UK
So far i have three choises the original Edcor from euros, the troidals (but as already said these may be a problem with the balancing) and then the OT from the previous post.
Hi Steve happy to see someone from Europe going to build this nice amp.
I already received the red board from Pete but I'd like to build the 50W version.
My idea is touch less possible the original scheme and only move to 450V-500V caps + a stronger B+
I’m trying to unify info for dummies in the main thread :
http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design-149.html
Up to now my big problem is to find a suitable power amp to use directly on the board, it should be (320-50-0-50-320) center tapped [Pete’s original is 280-50-0-50-280] , will try the sources that have been suggested.
Hammond 373-EX (325-0-50-325 at 300mA) may be good but how may I do with the 50-0-50? A voltage doubler?
Anyway...
Best luck for the project and will follow your reports with the biggest interest.
Cheers
Giuseppe (Madrid)
I already received the red board from Pete but I'd like to build the 50W version.
My idea is touch less possible the original scheme and only move to 450V-500V caps + a stronger B+
I’m trying to unify info for dummies in the main thread :
http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design-149.html
Up to now my big problem is to find a suitable power amp to use directly on the board, it should be (320-50-0-50-320) center tapped [Pete’s original is 280-50-0-50-280] , will try the sources that have been suggested.
Hammond 373-EX (325-0-50-325 at 300mA) may be good but how may I do with the 50-0-50? A voltage doubler?
Anyway...
Best luck for the project and will follow your reports with the biggest interest.
Cheers
Giuseppe (Madrid)
Hello giuseppe
thank you for joining the thread. as you know this is a European build and on a newbie bases. i have not myself looked at the power input side of this design. i find the output trannys more difficult to match. But some time this week i will look at the power side and what you have highlighted.
out of in interest what output transformers are you using?
As you stated this is a European build on this design. i can source a lot of components from the US but will end up paying more for postage and import tax.
if this goes well then this will make petes design more affordable in Europe.( i know from previous threads this has already been built in Europe. but the supply's have not been mentioned.)
I cant say much more at the moment as i have not had much time to look. hopefully by the end of the week i should have a decision on what transformers to use. but i will not buy till the PCB turns up as i need to see if this gets damaged in the post.
thank you for joining the thread. as you know this is a European build and on a newbie bases. i have not myself looked at the power input side of this design. i find the output trannys more difficult to match. But some time this week i will look at the power side and what you have highlighted.
out of in interest what output transformers are you using?
As you stated this is a European build on this design. i can source a lot of components from the US but will end up paying more for postage and import tax.
if this goes well then this will make petes design more affordable in Europe.( i know from previous threads this has already been built in Europe. but the supply's have not been mentioned.)
I cant say much more at the moment as i have not had much time to look. hopefully by the end of the week i should have a decision on what transformers to use. but i will not buy till the PCB turns up as i need to see if this gets damaged in the post.
You could use a small 50-0-50 toroidal transformer for the bias supply. Or, get Edcor to wind you a custom transformer.
jeff
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Thanks Jeff, wrote twice to Edcor through last two weeks to ask for a custom winding but get no answer.
The 50-0-50 toroidal solution....very simple and interesting...and put me out of trouble
Thanks
Still not focused on OPT, but they would be 50WPC at least.
Previous projects (Tubelab TSE and others) used all USA stuff --> high shipping
Which provider do you use for components (caps, resistors etc)??
I've been with Mouser but have to spend a (high) minimum $$ to have free shipping....
Regards
I will try my best to source the components from Europe.
US shipping is really expensive and will normally end up costing me more on handling and import taxes. Especially FedEx.
But if i'm importing from china or hong kong the postage is free and no import charges.
As for the power transformer 50 -0-50 supply why not use the original Edcor XMWR139.
There is a German supplier at the following address
https://www.don-audio.com/Edcor-XPWR139-120-240
US shipping is really expensive and will normally end up costing me more on handling and import taxes. Especially FedEx.
But if i'm importing from china or hong kong the postage is free and no import charges.
As for the power transformer 50 -0-50 supply why not use the original Edcor XMWR139.
There is a German supplier at the following address
https://www.don-audio.com/Edcor-XPWR139-120-240
gmonno : You mean through Ebay or via Aliexpress for example?
gmonno : because the original have a secundary of 280-50-0-50-280 and I want 320-0-.....
through ebay. depend on what you are buying. I bought a signal generator from hong kong and the postage was free.
Sorry did not realize you where going to 320 volts not sure how you can do this with out getting a transformer specially wound. there has been a few transformer supplier suggestion on this thread one will be able to supply what you need.
not sure how you would connect a separate 50-0-50 transformer to this design
Sorry did not realize you where going to 320 volts not sure how you can do this with out getting a transformer specially wound. there has been a few transformer supplier suggestion on this thread one will be able to supply what you need.
not sure how you would connect a separate 50-0-50 transformer to this design
European members should consider the offerings of AnTek. Pricing is favorable and shipping costs from New Jersey will be lower than from New Mexico (Edcor).
Sorry, I have no answer for the VAT, etc., issue. Don't feel alone. H.M.'s Bureau of Inland Revenue has nothing on the U.S. Treasury Dept.'s Internal Revenue Service. Tax collectors are among the lowest forms of life, with pretentions of being human.
Sorry, I have no answer for the VAT, etc., issue. Don't feel alone. H.M.'s Bureau of Inland Revenue has nothing on the U.S. Treasury Dept.'s Internal Revenue Service. Tax collectors are among the lowest forms of life, with pretentions of being human.
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Hello
I heard probably from Quad II repare site by the keith-snook that brand originally made OT for quad valve amps still working and they have old stock of laminations?
For GBrit members that could be the option? Maybe keith-snook can help with an information where in GB to order very good OT? cheers...
I heard probably from Quad II repare site by the keith-snook that brand originally made OT for quad valve amps still working and they have old stock of laminations?
For GBrit members that could be the option? Maybe keith-snook can help with an information where in GB to order very good OT? cheers...
PCB turned up today. in good condition, was a bit worried about the courier handling of it from the US. but all is well.
Can now start sourcing other components. thanks Pete
uploaded a picture. I know there is already some of these pics on the forum but thought another would not hurt
Can now start sourcing other components. thanks Pete
uploaded a picture. I know there is already some of these pics on the forum but thought another would not hurt
Attachments
Well I have decided on the transformers i'm going to use. I originally liked the Edcor transformers but did not want to courier them across from the US.
The price difference between the US Edcor and Europe's Don-audio.com Edcor supplier is only about £20 and they are in stock at the moment. The other transformer company's i have looked at are relatively the same price and most will require an additional winding for the 50-0-50 bias supply.
So i will go with the Edcor transformers from Don-audio.
I am not going to order them until i have all the components for the board.
So far i have a problem getting the 6jn6 valves over here in Europe. Pete has recommended a good site from the US which should have them but still waiting for a reply from them with postage cost.
Anyone in UK or Europe got 4 x 6JN6 valves they want to sell.
The 7 pin valve sockets will have to come from China as again no supply over here.
Not looked at the caps yet.
The price difference between the US Edcor and Europe's Don-audio.com Edcor supplier is only about £20 and they are in stock at the moment. The other transformer company's i have looked at are relatively the same price and most will require an additional winding for the 50-0-50 bias supply.
So i will go with the Edcor transformers from Don-audio.
I am not going to order them until i have all the components for the board.
So far i have a problem getting the 6jn6 valves over here in Europe. Pete has recommended a good site from the US which should have them but still waiting for a reply from them with postage cost.
Anyone in UK or Europe got 4 x 6JN6 valves they want to sell.
The 7 pin valve sockets will have to come from China as again no supply over here.
Not looked at the caps yet.
Here's another US company with suitable OPT's that's well respected
on the forums for not too much more than the Edcors and they are
sonically a step up as they they have more interleaving which helps
the highs. They only take about a week to have built.
Push-Pull Transformers - Transcendar Audio Transformers
on the forums for not too much more than the Edcors and they are
sonically a step up as they they have more interleaving which helps
the highs. They only take about a week to have built.
Push-Pull Transformers - Transcendar Audio Transformers
If that's the same Transcendar transformer that were selling on Ebay 2006-2009 I would pass. These made me go back to solid state after building a 300B DIY project.... I won't use the word "junk" but they sure didn't sound great and would probably be equal to a pair of chinese OPT's, lifeless when compared to my current OPTs from Intact Audio.
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