Manufacturer of  Ultra High Quality Audio Transformers
		Introduction (the Part number below, is the same as in the pricelist
Part 1		Tube Power Supply Chokes)			Tube Output transformers
Part 2		Filament Chokes / High Current Chokes	Part 22		Tube Mains transformers with DC cancellation
Part 3		Plate (anode)  Chokes	Part 23		Mains Cleaning transformers with DC cancellation
Part 4		Grid Choke	Part 24		Transformer Covers (Housings)
Part 5		Interstage	Part 25		Various transformers, not mentioned here
Part 6		Signal Input
Part 7		Signal Output
Part 9		Moving Coil
Part 10		Guitar Input	Tech1		(technical info) PPZ transformers
Part 11		Microphone	Tech2		(technical info) Product Storage
Part 12		For Digital Audio. Finest Quality	Tech3		(technical info) Amorph Cores
Part 13		Interconnect Solutions	Tech4		(technical info) DATASHEET DOWNLOAD

PP and SE Output transformers

Introduction

All types are made with the same size silicon iron C-core, and all types have the same secondary winding topology, but different primary windings.

Some types can be used for a number of different primary impedance levels by using different secondary terminations. The transformers are available in push-pull or single end versions with different core air-gap for different DC currents. The transformers are highly sectioned for excellent frequency response.

The use of C-cores and well defined air-gaps results in an almost constant inductance throughout the whole operating voltage range

The lundahl tube output transformers are available in a two versions.

1. FIXED IMPEDANCE Transformers with simply two connections for primary, and two connections for the secondary.

• The LL1663 is a 5k to 8 ohms output transformer available in PP or SE versions.
• The LL1664 is a 3k to 8 ohms output transformer available in PP or SE versions
• The LL1682 is a 5.5k to 5 ohms output transformer available in PP or SE versions
• The LL1691 is a 9k to 8 ohms output transformer available in PP or SE versions

These are available with following data:

NOTE: The Push Pull version is available as standard push pull, or as Push-Pull-Zero Version for the very audiophile PARAFEED applications. The parafeed transformers are a non-catalog product, and JACMUSIC supplies those on customer order, at no extra costs. The Parafeed have roughly twice the inductance as compared to standard products, and can take zero DC current. The standard PP Versions can take 15% DC Current offset, and keep all datasheet specifications while doing so. We can help you to convert a standard PP schematic to PARAFEED, it is usually very easy to do. Parafeed has a more tight bass control.

2. VARIABLE IMPEDANCE transformers, with normally three primary AND three secondary impedances to choose from.

These impedances are not chosen by a "tap" as with low cost transformers of this kind. A "tap" would mean the untapped part of the winding package remains unused, and the copper resistance and stray fields would go up without need. So at Lundahl you won't find this type.

With the Lundahl's the configurations are made by using all windings. So for each impedance you choose, there is the corresponding way of connecting windings in series and parallel, giving one of the three possible impedances. (both primary and secondary) You don't need to bother how that has to be done, there is just a table in each datasheet giving the connection scheme letter (From A to L). Then when you chose for instance "C", you know what the primary and secondary impedance is, and all you do is use Connection Scheme "C". These are given in the datasheet, and physically are shown as a hard wire schematic, directly on the transformer itself. It is really very easy, The result is then two primary wires, and two secondary wires, same as with a single impedance transformer.

The variable impedance transformers are recommended when you have not heard before the amplifier you are going to build, or when you have not heard, or intend to change your loudspeakers. Without going to much in detail about the reasons, it is MUCH recommended to try all three secondary impedances, no matter what the impedance of your speakers is.

(Many so called 4 Ohms speakers are in fact 6 Ohms, and 8 Ohm speakers can be 6 Ohms as well. Additional it is nothing unusual if a true 8 Ohms speaker sounds best at 4 Ohms, in your hearing environment. Another issue is that many speakers have their impedance go up (and some go down!) below 50...100 Hz. Of course the manufacturers won't tell you. So we can only say: TRY IT OUT with all three output impedances of the Lundahl transformers. That takes you only 10 minutes to re-wire, and that is a better way than all the tech babble about this subject).

The below tables are a handy overview. You will find another way to display the same information in the official datasheets.

NOTE: The Push Pull version is available as standard push pull, or as Push-Pull-Zero Version for the very audiophile PARAFEED applications. The parafeed transformers are a non-catalog product, and JACMUSIC supplies those on customer order, at no extra costs. The Parafeed have roughly twice the inductance as compared to standard products, and can take zero DC current. The standard PP Versions can take 15% DC Current offset, and keep all datasheet specifications while doing so. We can help you to convert a standard PP schematic to PARAFEED, it is usually very easy to do. Parafeed has a more tight bass control.

APPLICATION HELP:  How to select a Transformer
APPLICATION  HELP:  Some examples of transformer combinations

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(Last updated: 02-Jan-2012 15:46 )