zintolo,
You said: "What is the opinion about chokes on this specific project?
IMHO in this specific case higher Rdc chokes are worst than simple 10-22 Ohm resistors."
I do not know what resistor/choke in the circuit you are referring to (1,500 posts in this thread).
But if you mean a B+ supply, with a CRC with R = 22 Ohms; Versus a CLC with L = 5H 65 Ohm choke . . .
I will always use the 5H choke.
Examples:
1. A CRC filter with 50uF, 22 Ohm, 50uF and a known load current, gives a specific amplitude of ripple.
A CRC filter with 50uF, 0 Ohm jumper, 50uF and a known load current, gives about 70% of the above amplitude of ripple.
The capacitive reactance of a 50uF cap at 120Hz full wave rectification = 26.5 Ohms
22 Ohms resistor driving a 26.5 Ohm capacitor reactance is approximately 45 Degrees, -3dB ripple, 70%.
Versus a 0 Ohm jumper which has 1.4 x the ripple.
2. A CLC filter with 50uF, 5H 65 Ohm, 50uF and a known load current, gives a Much lower amplitude of ripple.
Yes, there is a little loss of B+ Volts: 65 Ohms x Load current (versus 22 Ohms x Load current of the CRC).
43 Ohms more Ohms than CRC, is well worth the tradeoff.
The inductive reactance of a 5H choke at 120Hz = 3,770 Ohms
The ripple attenuation is approximately 26.5 / 3770, 7%
3. The CLC ripple is only 7% of the ripple of the 22 Ohm CRC filter.
43 Ohms x 100mA load is 4.3V drop of B+ voltage. You get more than 4V B+ voltage change that is caused by most power mains voltage variations.
If the 22 Ohm versus Choke was not for a B+ application, then at least I discussed the differences of CLC and CRC filters.
Perhaps not a waste to read through all of that.
You said: "What is the opinion about chokes on this specific project?
IMHO in this specific case higher Rdc chokes are worst than simple 10-22 Ohm resistors."
I do not know what resistor/choke in the circuit you are referring to (1,500 posts in this thread).
But if you mean a B+ supply, with a CRC with R = 22 Ohms; Versus a CLC with L = 5H 65 Ohm choke . . .
I will always use the 5H choke.
Examples:
1. A CRC filter with 50uF, 22 Ohm, 50uF and a known load current, gives a specific amplitude of ripple.
A CRC filter with 50uF, 0 Ohm jumper, 50uF and a known load current, gives about 70% of the above amplitude of ripple.
The capacitive reactance of a 50uF cap at 120Hz full wave rectification = 26.5 Ohms
22 Ohms resistor driving a 26.5 Ohm capacitor reactance is approximately 45 Degrees, -3dB ripple, 70%.
Versus a 0 Ohm jumper which has 1.4 x the ripple.
2. A CLC filter with 50uF, 5H 65 Ohm, 50uF and a known load current, gives a Much lower amplitude of ripple.
Yes, there is a little loss of B+ Volts: 65 Ohms x Load current (versus 22 Ohms x Load current of the CRC).
43 Ohms more Ohms than CRC, is well worth the tradeoff.
The inductive reactance of a 5H choke at 120Hz = 3,770 Ohms
The ripple attenuation is approximately 26.5 / 3770, 7%
3. The CLC ripple is only 7% of the ripple of the 22 Ohm CRC filter.
43 Ohms x 100mA load is 4.3V drop of B+ voltage. You get more than 4V B+ voltage change that is caused by most power mains voltage variations.
If the 22 Ohm versus Choke was not for a B+ application, then at least I discussed the differences of CLC and CRC filters.
Perhaps not a waste to read through all of that.
It’s not a matter of location, it’s just at well over $800 for two power transformers and two output transformers is out of my budget for this build for the Toroidy supremes. Basically I want to disguise the toroids if I use them. It seems like the Toroidy power transformer is the only one recommended, so that may be a forgone conclusion to have to use it.
Have you tried looking for chrome toroid covers separately? Then the transformer bill is reduced. Else AliExpress and a wait for delivery can be an option, but you did state 'in the US'.
@6A3sUMMER
Thanks, I tried a choke I was used to use in guitar amps: Hammond 159R.
That one has a Rdc of 150 Ohm (that is what I meant with "higher") that it is true has better ripple rejection, but very high drop in voltage (up to 30V) when the amp is pushed, compared to the small resistor. In this specific circuit, where we have a PP and a LTP phase inverter, ripple isn't that much problematic, so that's why I preferred the low value resistor.
I'm sure that more expensive chokes with lower Rdc will perform way better.
In guitar amps indeed I always prefer to have chokes rather then resistors, but over there higher impedance power supplies are almost a must.
Thanks, I tried a choke I was used to use in guitar amps: Hammond 159R.
That one has a Rdc of 150 Ohm (that is what I meant with "higher") that it is true has better ripple rejection, but very high drop in voltage (up to 30V) when the amp is pushed, compared to the small resistor. In this specific circuit, where we have a PP and a LTP phase inverter, ripple isn't that much problematic, so that's why I preferred the low value resistor.
I'm sure that more expensive chokes with lower Rdc will perform way better.
In guitar amps indeed I always prefer to have chokes rather then resistors, but over there higher impedance power supplies are almost a must.
Just emailed TME about shipping for 2 OPT and 2 PT. They responded that they couldn’t sell these items to the US.
So this project just went in the toilet for me. Glad I was purchasing the transformers first.
This is the second time I’ve had shipping short me this week. Had a set of used Lii Audio F15’s lined up and paid for and the guy backed out because he couldn’t find the original shipping boxes and was afraid they’d get damaged.
So this project just went in the toilet for me. Glad I was purchasing the transformers first.
This is the second time I’ve had shipping short me this week. Had a set of used Lii Audio F15’s lined up and paid for and the guy backed out because he couldn’t find the original shipping boxes and was afraid they’d get damaged.
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I think you can order direct from Toroidy. A vintage pair of Scott or Fisher 7591/7868 type outputs would work great and are usually in the 6-7k primary range. Can often find them at auction. There is a Greek seller on eBay that might have something good. I saw some measurements of one model of his SE output and it looked very good so the PP choices might be a good bet as well. Heyboer has some output designs in this power and impedance range.
You might also talk to Matt at Musical Power Supplies. He has a number of PP HiFi designs and will do custom winds on request. I haven't used his PP outputs but his small SE HiFi outputs are really good. Very nice pricing too.
https://www.musicalpowersupplies.com/
You might also talk to Matt at Musical Power Supplies. He has a number of PP HiFi designs and will do custom winds on request. I haven't used his PP outputs but his small SE HiFi outputs are really good. Very nice pricing too.
https://www.musicalpowersupplies.com/
I’ve used Matt’s transformers in guitar amps with good luck.
The OPT really isn’t an issue. Several options there, but the power trafo is another matter. Looks like I might have to have a B+ and a separate 50V ?
Love to, but that's why I DIY most of my stuff, because I don't have enough saved up to buy all at once. They are lovely though.
This is news to me. Sorry to hear. Hope it is a novice clerk that provided incorrect information in response to your email inquiry.
Have you tried to order directly online from the TME website? Order one transformer at a time for the under 5 Kg package that ships at $9.99 from Poland to the USA. (The EL34 output and power transformers are above the limit in pairs). That is how I have done business and always had very good luck. I bought a pair of Toroidy ECL86 PP output transformers (a pair of these weighs in at under 5 kg packed) about three months ago with no issues for $9.99 shipped
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I haven't tried to order yet. I'm thinking that I can get the OPT's on their site, but I do get a message that they won't ship the PT whenever I actually go to my cart. It's the PT that I really need. There are other options for the OPT's.
This is close I think: https://edcorusa.com/collections/tu...-100v300-50-0-50-300-325ma-ct-6-4v-4a-6-3v-4a
or maybe this, although a little low on the B+ and high on the bias tap: https://edcorusa.com/products/xpwr078-500v-400ma-ct-60v-50ma-6-3v-7a?_pos=6&_sid=edaaf6910&_ss=r
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I remember reading a message recently that TME established a presence in USA (Georgia I think). Perhaps that is why you can’t buy from Poland TME now. Don’t give up on Toroidy yet. I expect that you should be able to buy Toroidy in USA
The Edcor transformer should work, however, a bit expensive (and overkill) for two if you need monoblocks.
The Edcor transformer should work, however, a bit expensive (and overkill) for two if you need monoblocks.
They did evidently. Had to google it.
https://www.tme.com/us/en-us/about-us/tme-group/38715/tme-us-llc/
I've sent an email to the US subsidiary. We shall see. In the meantime I'd like to find an alternative power transformer(s).
https://www.antekinc.com/tube-amp-parts/
https://www.ebay.com/itm/254693606897
https://www.ebay.com/sch/i.html?_ss...=antekinc&_oac=1&_trksid=p4429486.m3561.l2562
they also sell on eBay, all free shipping
https://www.tme.eu/de/pl/details/ttg-el34pp/transformatory-toroidalne/toroidy/
TME also sells from the manufacturer TOROIDY, otherwise there are inquiries about shipping to the USA if that is what you really need.
https://www.ebay.com/itm/254693606897
https://www.ebay.com/sch/i.html?_ss...=antekinc&_oac=1&_trksid=p4429486.m3561.l2562
they also sell on eBay, all free shipping
https://www.tme.eu/de/pl/details/ttg-el34pp/transformatory-toroidalne/toroidy/
TME also sells from the manufacturer TOROIDY, otherwise there are inquiries about shipping to the USA if that is what you really need.
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