Please check the data sheets carefully.... Many Triad low VA types have high copper losses. This shows up as much worse regulation than Hammond.
I have not checked, but I suspect that these will also run at high core B field - meaning high iron loss and flux spillage. I don't think they are a good choice for audio!
Hello,
If i remember well Mouser also sells Signal and Hammond split bobbin transformers.
They are easy to make so that is the reason they are not expensive. Some of them seem to be manufactured in a more precise way. Just study the photos.
Rod and some others claim they work well to stop garbage from entering your precious gear.
Greetings, Eduard
P.s it would be good to compare some specs here if they are available and come up with some recommendations
If i remember well Mouser also sells Signal and Hammond split bobbin transformers.
They are easy to make so that is the reason they are not expensive. Some of them seem to be manufactured in a more precise way. Just study the photos.
Rod and some others claim they work well to stop garbage from entering your precious gear.
Greetings, Eduard
P.s it would be good to compare some specs here if they are available and come up with some recommendations
The raw DC is inside the chassis. I run tightly twisted pairs to the regs. Is that sufficient?
For -filament biased- #26 LT PSU even this PT may be appropriate (before R.C. regulator).
https://www.tme.eu/gb/details/ts40_030/transformers-with-fastening/indel/ts-40-030/
https://www.tme.eu/gb/details/ts40_030/transformers-with-fastening/indel/ts-40-030/
Nothing against Hammond, I have some of them as well. The actual transformers I bought from Triad are the FP230-50 (which I use as PS choke in a OTL amplifier and as an anode load in a PP amplifier) and 1 small toroidal with 230V secondary, used for powering a driver stage. I have just been looking at some other offers they have that could work for tube amps "on the cheap". OTOH, with all the work that goes into an amp, I do not think it is wise to specifically save on the power transformers, but a compromise?! Also, many companies will not ship to Switzerland. When they do, it is expensive: toroidy quoted circa 80 USD for 5kgs with DHL, on top of that comes the taxes and blablabla....
I also gathered so many different materials up to some 10 years ago that currently I do not actually need new power transformers, just working with the stuff I have. Having said all that, what about this power transformer, dual bobbin, 2x 115VAC at the secondary and 175VA, for about 36 EUR (excl.VAT). https://eu.mouser.com/datasheet/2/410/VPS230_760-781512.pdf for a B+ of about 300VDC? This same line has transformers with lower voltage secondaries. I would probably not run them at their rated max power..
I also gathered so many different materials up to some 10 years ago that currently I do not actually need new power transformers, just working with the stuff I have. Having said all that, what about this power transformer, dual bobbin, 2x 115VAC at the secondary and 175VA, for about 36 EUR (excl.VAT). https://eu.mouser.com/datasheet/2/410/VPS230_760-781512.pdf for a B+ of about 300VDC? This same line has transformers with lower voltage secondaries. I would probably not run them at their rated max power..
Garbage is one thing and hum maybe another? Toroids at least don't generate hum fields.
I use Mouser and Digikey with caution because of increased charges in the UK. My go-to is CPC/Farnell, Rapid and RS. Hammond from KGA has doubled in price this year, alas.
For the B+ Airlink do a 230-230V toroid in various VA. I've used the 30VA one.
https://airlinktransformers.com/category/chassis-mounting-toroidal-transformers-standard-range
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If you see first pic here https://www.diyaudio.com/community/threads/26-pre-amp.151421/page-271#post-7550021 I also use twisted -DC- wires from umbilical connector to R.C. regulators.
Alt. T
Primary Inductance 33H
Freq. Response (+/-1dB) 25 Hz - 30 kHz
@ source impedance (max) 3.5kOhm
Secondaries open
The source impedances used in the tables indicates a recommended upper limit, unless freq. response can be compromised.
At lower source impedance resonance peaking will occure. It can be reduced using secondary load resistors.
33H at 20Hz about 4k1 impedance.
You must to use driving it with -max- 1k3 output impedance device ..... then must to use on secondary (few kOhm, circa 10-20k) resistive load to damp resonance bump... so "6dB gain" flew away.
No free lunch.
Primary Inductance 33H
Freq. Response (+/-1dB) 25 Hz - 30 kHz
@ source impedance (max) 3.5kOhm
Secondaries open
The source impedances used in the tables indicates a recommended upper limit, unless freq. response can be compromised.
At lower source impedance resonance peaking will occure. It can be reduced using secondary load resistors.
33H at 20Hz about 4k1 impedance.
You must to use driving it with -max- 1k3 output impedance device ..... then must to use on secondary (few kOhm, circa 10-20k) resistive load to damp resonance bump... so "6dB gain" flew away.
No free lunch.
I repeat again: if you drive this transformer with low output impedance tube (MUST to drive with this, because primary inductance is relatively low), MUST to load secondary with relatively low resistor, because this transformer -due to such circumstances- has large bump!
When you said "if you drive this transformer with low output impedance tube" are you refering to 26?
No.
#26 has 7k3...8k9 output impedance, so practically unsuitable to drive well LL1660 in Alt T (source impedance (max) 3.5kOhm), which transformer primary is 4k1 impedance at 20Hz (33H) .
#26 requires at least 120H as anode load.
p.s.
In my old #26 preamp I use CCS as anode load and capacitor coupled 400H TVC as volume controller. See 5416 post.
#26 has 7k3...8k9 output impedance, so practically unsuitable to drive well LL1660 in Alt T (source impedance (max) 3.5kOhm), which transformer primary is 4k1 impedance at 20Hz (33H) .
#26 requires at least 120H as anode load.
p.s.
In my old #26 preamp I use CCS as anode load and capacitor coupled 400H TVC as volume controller. See 5416 post.
If you don't use enough impedance transformation (scaling up to #26 anode), the 4k1 impedance at 20Hz can cause a problem just the same.
The #26 requires at least 15k-18k impedance loading at the lower region, which is result of all loading (anode load paralleled the AVC impedance paralleled the transformed impedance of AVC loading etc.).
Please sketch the schematic to avoid misunderstandings.
The #26 requires at least 15k-18k impedance loading at the lower region, which is result of all loading (anode load paralleled the AVC impedance paralleled the transformed impedance of AVC loading etc.).
Please sketch the schematic to avoid misunderstandings.
