From EU countries, 10% basic tariff came into effect last Saturday. In addition, an additional 20% tariff will come into effect next Wednesday.
Have you not heard about these?
I've had great results ordering signal transformers from Cinemag.
They are set up like an industrial supply house. You call em and tell em what you need and they either ship it or make it then ship it. I trust the product and I can call directly to the gentleman who oversees production and talk with him directly about technical details.
They are in California and their prices are extremely competitive if you buy direct.
I'm looking for someone in the USA who can offer the same for torroids. That way I can develop a working relationship with someone and buy direct going forward...
As a matter of pride i do my very best to source quality stuff for my builds, which includes supporting quality manufacturers in my home country.
In my opinion it has always been the correct thing to do weather tariffs apply or not. Shipping costs money and so does quality labor and at the end of the day nobody is giving away 6550 push pull monoblock amps with low impedance power supplies...
Buy once cry once, gotta spend some money to have something worthwhile.
I'm not saying Antec are bad transformers but they're obviously not proud of where they're sourced...
Be proud of every aspect of what you produce. Every tiny detail matters and is worth obsessing over.
I worked at a shop where we middled Chinese starters and alternators and all day folks would come spend way too much money on them because they were being sold by an Englishman who in their minds built the product, but in reality it was built in China.
He put his name on the box doubled the price and bobs your uncle...
This is what Antec is doing and I want no part in it.
They are set up like an industrial supply house. You call em and tell em what you need and they either ship it or make it then ship it. I trust the product and I can call directly to the gentleman who oversees production and talk with him directly about technical details.
They are in California and their prices are extremely competitive if you buy direct.
I'm looking for someone in the USA who can offer the same for torroids. That way I can develop a working relationship with someone and buy direct going forward...
As a matter of pride i do my very best to source quality stuff for my builds, which includes supporting quality manufacturers in my home country.
In my opinion it has always been the correct thing to do weather tariffs apply or not. Shipping costs money and so does quality labor and at the end of the day nobody is giving away 6550 push pull monoblock amps with low impedance power supplies...
Buy once cry once, gotta spend some money to have something worthwhile.
I'm not saying Antec are bad transformers but they're obviously not proud of where they're sourced...
Be proud of every aspect of what you produce. Every tiny detail matters and is worth obsessing over.
I worked at a shop where we middled Chinese starters and alternators and all day folks would come spend way too much money on them because they were being sold by an Englishman who in their minds built the product, but in reality it was built in China.
He put his name on the box doubled the price and bobs your uncle...
This is what Antec is doing and I want no part in it.
I have found Antek output transformers pretty hard to beat for the price to performance ratio for smaller builds in North America.
Yes they come from a USA that seems to have gone crazy lately so that may now be a issue buying them.
I have used them for a number of PP builds in the 10 to 20 watt range.
They have low leakage inductance and stray capacitance is reasonable for good 20Khz performance.
Bias current balance in the output tubes is important to realize good low THD at low frequencies so I include some sort of bias adjustment in the output stage with these transformers.
Overall you can build a fine amplifier with these in the 10 to 20 watt range in my experience.
I have no experience with the larger higher power output transformers from Antek as I have gone with Hammond for higher power output transformers
Yes they are made in China but not everything from china is low quality. (Think most iphones)
Yes they come from a USA that seems to have gone crazy lately so that may now be a issue buying them.
I have used them for a number of PP builds in the 10 to 20 watt range.
They have low leakage inductance and stray capacitance is reasonable for good 20Khz performance.
Bias current balance in the output tubes is important to realize good low THD at low frequencies so I include some sort of bias adjustment in the output stage with these transformers.
Overall you can build a fine amplifier with these in the 10 to 20 watt range in my experience.
I have no experience with the larger higher power output transformers from Antek as I have gone with Hammond for higher power output transformers
Yes they are made in China but not everything from china is low quality. (Think most iphones)
Toroids weigh about half of what EI core transformers weigh for the same VA rating. Using a full-wave bridge or full-wave voltage doubler gets about 40% more DC power from a given VA rating than full-wave center-tap (or putting it another way, using a center-tapped transformer like most Hammonds and Edcors wastes 30% of the VA rating). Enclosing them will increase temperature rise, so derate them a bit (70% of current rating means half the heat).
Output transformers are another story - I have zero experience with toroids but they seem to measure well.
Output transformers are another story - I have zero experience with toroids but they seem to measure well.
Last edited:
Antek transformers,definitely value for the money,but you get what you pay for.low price,less copper,poor regulation. 6.3vac @ 3amps.mmm. more like 6.08vac.
To be crystal clear I'm not considering using them as output transformers.
I've already got 4x Dynaco A-430s which are potted and they're hard to beat in terms of raw specs.
I've already got 4x Dynaco A-430s which are potted and they're hard to beat in terms of raw specs.
De minimis still applies for EU->US for now. So if your order is under $800 you shouldn't have to deal with it.
Obvious caveats:
A) There is clear indications they want to remove it for EU and other places once the infrastructure to process it is in place, but there's no ETA for de minimis elimination other than for China & HK (May 2nd for those).
B) Prices will certainly start to rise even if de minimis remains in effect for a while.
If your Amp uses a toroid power transformer, those have higher inrush at turn on. So a Chinese inrush module board that fits in the enclosure you might want to think of. I have a friend who uses monster sized class A amplifiers (not class D), when he switched on his system the house lights used to dim So he wired in a few of these 10 thermistor soft start boards, now his amps turn on smoothly. I guess EL transformers don't exhibit as much inrush current. Thats the only difference I can see that matters between them.
https://www.ebay.com/itm/134143344561
https://www.ebay.com/itm/134143344561
Inrush currents are high on toroids because of core saturation. When switched on, there is a momentary DC offset because it can’t be switched on at zero amps and zero volts simultaneously (primary L ensures that). The time constant for it to decay to zero can be several seconds. The whole time that happens the core is getting hammered and drawing a lot of magnetizing current. EIs are more tolerant of that DC offset and the current isn’t as crazy.
Hungry caps aren’t as big a deal with tube amps as with solid state because all the impedances are higher. There is enough DCR to keep it from dimming the lights, and the smaller cap values help too. But that DC offset issue is just a function of the size of the trafo (VA rating, as it determines what primary is on it).
Any type of soft start circuit will deal with it.
Hungry caps aren’t as big a deal with tube amps as with solid state because all the impedances are higher. There is enough DCR to keep it from dimming the lights, and the smaller cap values help too. But that DC offset issue is just a function of the size of the trafo (VA rating, as it determines what primary is on it).
Any type of soft start circuit will deal with it.
I routinely incorporate a 5~10 ohm cold resistance NTC in the primary to soften the startup current surge.
This also tends to prevent nuisance fuse failures.
After the NTC warms up the voltage loss is normally under 1 volt.
See attached for suggestions.
This also tends to prevent nuisance fuse failures.
After the NTC warms up the voltage loss is normally under 1 volt.
See attached for suggestions.
If these power amplifiers dim the house lights when I power them up, that would be cool, and if they dim lights all up and down the street that would be even cooler.
Build something like that and word gets around....
"What happens at 6pm every second Saturday to cause the lights to dim?
That's just Tony the Wrench plugging in his tube PA system for the tempo party!
I’ve got a 40 watt per channel class B SS amp that causes the lights to dim when switched on. You can hear the transformer go “Brrrmmp”. It’s only got 6800 uF cap, so that sumbich is saturating. The supply has exceptional regulation for a 300 VA unit - and the way to get that is to make the wire as short as possible, fewer turns per volt, run higher up the BH curve. More sensitive to DC transients. Doesn’t blow fuses and has output caps to protect speakers so I don’t worry about it.
I have amps two orders of magnitude larger that have soft start, but make the lights dim at war volume. My biggest tube amps have delayed B+ and power tube heaters. Waits for the whole front end and screen V to stabilize first, before even heating the power stage up. If anything goes amiss, it shuts off the 600V and 6550 heaters. The power stage trafos (dual AS4T430’s) just have a 12 amp PTC thermistor in series.
I have amps two orders of magnitude larger that have soft start, but make the lights dim at war volume. My biggest tube amps have delayed B+ and power tube heaters. Waits for the whole front end and screen V to stabilize first, before even heating the power stage up. If anything goes amiss, it shuts off the 600V and 6550 heaters. The power stage trafos (dual AS4T430’s) just have a 12 amp PTC thermistor in series.
A soft start board is one of those things I'd rather not spend time on making myself, rather just buy a board that will fit, here are some others I found: In one of the comments a guy used his fluke to capture max amps in the first 1/1000 of a second with his Adcom GFA555 (a classic 1990's amp that I still use), he measured upwards of 30 amps! One of the Amazon ones below seems way over complicated with a 555 timer. There is no reason for the shorting relay to be open for longer than 1 second, maybe 1/2 second. One commenter said his 555 timer model kept the relay open for 5 seconds and burnt out the thermistors as the pot was set to midway and of course no instructions ever come with Chinese boards. I like the ones that seem uncomplicated with 30 amp relays that close under 1s, just enough to tap the brakes.
https://www.ebay.com/itm/134610537104
https://www.ebay.com/itm/134143344561
https://www.ebay.com/itm/296499294052
https://www.ebay.com/itm/316585131553
https://www.amazon.com/6600W-Protec...module&qid=1744401332&sprefix=,aps,95&sr=8-10
https://www.amazon.com/Electronics-...module&qid=1744401381&sprefix=,aps,95&sr=8-19
Just a thermistor in series works pretty well on tube amps, since they deal with the residual handful of ohms better than a big transistor amp does.
I don't use boards in my builds and I certainly don't piece together pre-made bits into a box full of circuit boards. That's not my style at all and I see zero challenge in it. If I do have to use a board, I design and produce it myself because I don't trust anyone to do anything right anymore.
Here's an example of my workmanship so you can tell that I'm serious...
I DIY because it's the only way to get what I need in life.
First came this mc/mm phono and line preamp, which I've made a bunch of..
Soon ill get started buying stuff for a 8/10 channel PA rig using all tube amplification and a tube mixer...
Attachments
Big advantage of toroidal transformers is low magnetic field strays and short mean length of turn, which results in low DC resistance in the windings. Big problem with them is that if the core satiates, which comes on abruptly, large spike current can occur. In a power transformer, It's advisable to properly fuse the primary of the transformer to prevent a catastrophic over-current condition.
Very nice. I am also avoiding pre-made boards, mechanically they never fit for me. Also when the maker of the board does an upgrade, they often go and stupidly change all the mounting hole centers, device centers that you need to heatsink, even the board size. So basically they are telling everyone that once bought their board that they can't upgrade without re-drilling chassis and heatsink holes! In my current build I will need inrush board because it contains 3 toroids. So that I'll buy. also there is no getting around the Coleman regulator boards by making those myself. I just hope Rod keeps the hole centers the same with his next version! Otherwise it is point to point and the only boards I'll make is for the input relays and the left/right driver stage boards, so I can try out different driver stages by simply making a new board with the same size and hole centers. I too am against cobbling together boards, I get no traction on the mechanical aspects just accommodating other boards. I know where you're coming from.
