Hello,
I'm looking for a top-grade OPT for Type 45 triode. What I can see are 'universal' types with primary taps 2.5 to 5k and secondaries to suit 4,8, and 16 ohm speakers.
Is there a consensus on 'the' high-end dedicated 'off the shelf' transformer for Type 45?
Thank you,
JP
I'm looking for a top-grade OPT for Type 45 triode. What I can see are 'universal' types with primary taps 2.5 to 5k and secondaries to suit 4,8, and 16 ohm speakers.
Is there a consensus on 'the' high-end dedicated 'off the shelf' transformer for Type 45?
Thank you,
JP
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Hashimoto --JAPAN --not China gets a good write up by top end audio companies .
Primary should be 4000ohms-5000ohms .
Ra is in the same range depending on the make and operating conditions .
Heavy duty versions are available .
H-20-7U_1024.jpg (JPEG Image, 1024 × 724 pixels)
Primary should be 4000ohms-5000ohms .
Ra is in the same range depending on the make and operating conditions .
Heavy duty versions are available .
H-20-7U_1024.jpg (JPEG Image, 1024 × 724 pixels)
Electraprint in the USA Electra-Print.com High-Fidelity Audio Tranformers and Tube Amplifers
Search - there are lots of old posts about this topic. Any of these suppliers will have a product suitable for the 45.
Search - there are lots of old posts about this topic. Any of these suppliers will have a product suitable for the 45.
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Electra-Print OPTs sound really nice on my 45 tube amp. Good price, prompt delivery, good communication with Jack.
Any opinions on using 3K or 3.5K OPTs on the 4 ohms tap?
Have any of you had good experiences?
They're a little more common than 5K OPTs and may come up used.
Have any of you had good experiences?
They're a little more common than 5K OPTs and may come up used.
Budget dependent, but I would highly recommend contacting Monolith Magnetics. I have used a number of their transformers in my own designs and they are top shelf.
Welcome to MONOLITH MAGNETICS | MONOLITH MAGNETICS
Welcome to MONOLITH MAGNETICS | MONOLITH MAGNETICS
andyjevans,
For a Real 45 tube (not a currently manufactured modern special re-designed 45),
A 3k or 3.5k primary and the 4 Ohm output tap is OK, If all the following are true . . .
1. The loud speaker minimum impedance is 6 Ohms or more
If you have no other way to measure that, then consider measuring the speaker DCR with a DMM. DCR also needs to be no less than 6 Ohms.
2. The output transformer primary DC current rating is at least 50 mA.
3. The output transformer primary inductance is at least 15 Henry, preferably 30 Henry.
4. The output transformer primary impedance is 3k or 3.5k.
5. The manufacturer of the output transformer is not lying about the specifications listed in # 2, 3, and 4 above.
With good power supply and good amplifier circuit design, and the above output transformer,
The amplifier will sound . . . Wonderful!
“Those who do not know history, are not aware that we are 'in' Deja Vu.
For a Real 45 tube (not a currently manufactured modern special re-designed 45),
A 3k or 3.5k primary and the 4 Ohm output tap is OK, If all the following are true . . .
1. The loud speaker minimum impedance is 6 Ohms or more
If you have no other way to measure that, then consider measuring the speaker DCR with a DMM. DCR also needs to be no less than 6 Ohms.
2. The output transformer primary DC current rating is at least 50 mA.
3. The output transformer primary inductance is at least 15 Henry, preferably 30 Henry.
4. The output transformer primary impedance is 3k or 3.5k.
5. The manufacturer of the output transformer is not lying about the specifications listed in # 2, 3, and 4 above.
With good power supply and good amplifier circuit design, and the above output transformer,
The amplifier will sound . . . Wonderful!
“Those who do not know history, are not aware that we are 'in' Deja Vu.
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Thanks for the replies.
I notice that neither Hashimoto (H20-7U), Monolith Magnetics (S11), or ISO (FC20S) mention Type 45 under 'application/to suit'. I also note that they are all gapped for use of up to 100mADC. The multi-primary configuration of the two Japanese transformers and with such a wide air-gap really does make them 'universal', and for that sort of money, for someone wanting to use specifically Type 45, I am wondering whether it makes more sense to buy a transformer specified specifically for the job, and I also wonder why there is not within their line-up one specific for Type 45 - none of these are in-expensive.
Monolith Magnetics is encouraging at least in that they say 'optimized for 300B at 400V and 80mADC', so, it seems there is such a thing. Perhaps they can optimize one for Type 45. I shall investigate.
Tamura F475, 5k primary gapped 45mA, appears to be just the thing yet not available as a new item.
As to Electra-Print, their online menu makes perfect sense. Build the transformer specific to the tube.
JP
I notice that neither Hashimoto (H20-7U), Monolith Magnetics (S11), or ISO (FC20S) mention Type 45 under 'application/to suit'. I also note that they are all gapped for use of up to 100mADC. The multi-primary configuration of the two Japanese transformers and with such a wide air-gap really does make them 'universal', and for that sort of money, for someone wanting to use specifically Type 45, I am wondering whether it makes more sense to buy a transformer specified specifically for the job, and I also wonder why there is not within their line-up one specific for Type 45 - none of these are in-expensive.
Monolith Magnetics is encouraging at least in that they say 'optimized for 300B at 400V and 80mADC', so, it seems there is such a thing. Perhaps they can optimize one for Type 45. I shall investigate.
Tamura F475, 5k primary gapped 45mA, appears to be just the thing yet not available as a new item.
As to Electra-Print, their online menu makes perfect sense. Build the transformer specific to the tube.
JP
I too have dealt with Jack Elliano at Electra Print Audio many times.
I do like his transformers.
Real easy to get a design that is specific to the tube, quiescent operating conditions of plate voltage, plate current, and bias voltage; and the loudspeaker's nominal impedance.
One time when I brought one of his transformers with me on the plane back from CES, the X-ray people pulled me aside. They wanted to know what was Below that Transformer (they could not see through the transformer, so simply wanted a physical look at my carry on bag). After that, I was happily on my way.
Be sure to find out the minimum speaker system impedance (usually the same as the DCR measured across the speaker system's input terminals).
Do that, before you pick a secondary impedance for the Electra Print output transformer.
I have several different types of "8 Ohm" speaker systems, many of them have a minimum impedance of 6 Ohms, and at least one type's minimum impedance is closer to 3.5 Ohms.
Nominal ratings are just that, nominal.
Cut it out posters!
If you posters do not stop talking about 45 DHT amplifiers, I am going to have to build one again (I had one before, used it at work, sounded great after 5:00 when almost everybody went home). I loved it when that lady came over from several aisles away, and told me how beautiful it sounded.
Want to go less expensive, get a One Electron UBT-2 from Antique Radio Supply.
Or go to Monolith Magnetics, they might design a custom one for you, and then they can advertise a 45 output transformer for the flock of others who will come to purchase them too (well a few who can afford that).
Build using that, and tell us about it.
Happy designing, happy building, and happy listening!
“Those who do not know history, are not aware that we are ‘in’ Deja Vu.”
I do like his transformers.
Real easy to get a design that is specific to the tube, quiescent operating conditions of plate voltage, plate current, and bias voltage; and the loudspeaker's nominal impedance.
One time when I brought one of his transformers with me on the plane back from CES, the X-ray people pulled me aside. They wanted to know what was Below that Transformer (they could not see through the transformer, so simply wanted a physical look at my carry on bag). After that, I was happily on my way.
Be sure to find out the minimum speaker system impedance (usually the same as the DCR measured across the speaker system's input terminals).
Do that, before you pick a secondary impedance for the Electra Print output transformer.
I have several different types of "8 Ohm" speaker systems, many of them have a minimum impedance of 6 Ohms, and at least one type's minimum impedance is closer to 3.5 Ohms.
Nominal ratings are just that, nominal.
Cut it out posters!
If you posters do not stop talking about 45 DHT amplifiers, I am going to have to build one again (I had one before, used it at work, sounded great after 5:00 when almost everybody went home). I loved it when that lady came over from several aisles away, and told me how beautiful it sounded.
Want to go less expensive, get a One Electron UBT-2 from Antique Radio Supply.
Or go to Monolith Magnetics, they might design a custom one for you, and then they can advertise a 45 output transformer for the flock of others who will come to purchase them too (well a few who can afford that).
Build using that, and tell us about it.
Happy designing, happy building, and happy listening!
“Those who do not know history, are not aware that we are ‘in’ Deja Vu.”
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I suspect the OP wants to throw some money at this and get something truly special.
On the cheaper end I've used the Lundahl LL1682 on a low power 300b at around 250v a-k and I liked that quite a lot. The best sounding of the Lundahl OPTs I've had (c.f. LL1664, LL1620, LL1623). I imagine it would suit a 45, though I don't have any to try.
On the cheaper end I've used the Lundahl LL1682 on a low power 300b at around 250v a-k and I liked that quite a lot. The best sounding of the Lundahl OPTs I've had (c.f. LL1664, LL1620, LL1623). I imagine it would suit a 45, though I don't have any to try.
Monolith Magnetics ETU series(if I know correctly ETUDE series is obsolete now).
ETU-3/2K5 2K5 SE 2A3 7-87,000 Hz 87X71X102 2 kg 271,3 € 224,2 €
ETU-3/5K 5K SE 45 7-87,000 Hz 87X71X102 2 kg 271,3 € 224,2 €
ETU-1 3K3 SE 300B, KT88 7-98,000 Hz 108X89X107 4 kg 295,7 € 244,3 €
ETU-3/2K5 2K5 SE 2A3 7-87,000 Hz 87X71X102 2 kg 271,3 € 224,2 €
ETU-3/5K 5K SE 45 7-87,000 Hz 87X71X102 2 kg 271,3 € 224,2 €
ETU-1 3K3 SE 300B, KT88 7-98,000 Hz 108X89X107 4 kg 295,7 € 244,3 €
The Tamura F-475 is not in production anymore but not rare to find as used in mint conditions or even New-In-Box....worth every penny. Simply the best of commercial product off-the-shelf for this application.
Monolith definitely will do a custom transformer... at a price. Excellent products anyway.
Sowter produces the SA02 model which is the closest to the F-475 in terms of specifications. It is sold as EL84 SE transformer likely because the EL84 is a tube still in production and more common.
Monolith definitely will do a custom transformer... at a price. Excellent products anyway.
Sowter produces the SA02 model which is the closest to the F-475 in terms of specifications. It is sold as EL84 SE transformer likely because the EL84 is a tube still in production and more common.
Is there a drawback in using a higher current OPT for the small 45 anode current (typical 34mA)? Looking at well known Japanese iron they seem rather big for the job. For instance the Tango XE-20S is a 20W unit while the 45 will use circa 180Vx0,033A=6W.
higher current rating = bigger air gap for the same size = less inductance = more distortion at low frequency. It can be used but it's not ideal.....
The fact that the transformer will work a lower induction and will use less headroom is not a disadvantage. If the bigger transformer has good inductance then no problem at all. Just bigger and heavier.
But the low frequency power rating does depend on the anode current and this is a good commercial reason to not offer low current transformer if the choices have to be made. Power sells more....
The fact that the transformer will work a lower induction and will use less headroom is not a disadvantage. If the bigger transformer has good inductance then no problem at all. Just bigger and heavier.
But the low frequency power rating does depend on the anode current and this is a good commercial reason to not offer low current transformer if the choices have to be made. Power sells more....
Thomas suggested 5k or 7k on his blog
VinylSavor: Tube of the Month: The 45
As the 45 is good for only a couple of watts wouldn't it be better too go with a smaller iron, such the Hashimoto 507s. I've got a pair of the H-203s, not used them yet, but build quality is first class.
I'm intrigued by Softone's r-core transformers; quite cheap compared to other Japanese transformers.
I guess you must have rather efficient speakers to be considering 45's on the output.
VinylSavor: Tube of the Month: The 45
As the 45 is good for only a couple of watts wouldn't it be better too go with a smaller iron, such the Hashimoto 507s. I've got a pair of the H-203s, not used them yet, but build quality is first class.
I'm intrigued by Softone's r-core transformers; quite cheap compared to other Japanese transformers.
I guess you must have rather efficient speakers to be considering 45's on the output.
With Monolith be sure to contact them. Ward de Ceuninck is a professor at Hasselt University and is really into the physics behind all of this, I'm sure he can answer any question you might have. He's a very approachable guy, I randomly bumped into him when I was still a student. I asked one of the electronics guys a question about the 12AU7 hybrid I was trying to build and he pointed me towards Ward who happened to be in the room and he gave me some great tips. Later on I happened to work for a while in the same building and every now and then the chatting would turn to his transformers (by then I realized what was going on 😀 ) and well... he sure has passion and knowledge for this kind of stuff.
mini disclaimer, I have no ties to the company or something, I just know one of the two guys running it and know that he has some deep knowledge about the physics behind it.
mini disclaimer, I have no ties to the company or something, I just know one of the two guys running it and know that he has some deep knowledge about the physics behind it.