[L0rdGwyn]

Glad to see your Berlin (Odyssey) amplifier is finally being built, @UntilThen . It has been a long time coming, I think you will be very happy with the Sowter iron

 

[UntilThen]

Glad to see your Berlin (Odyssey) amplifier is finally being built, @UntilThen . It has been a long time coming, I think you will be very happy with the Sowter iron

Thanks mate. It will be bigger and has more configurations than Berlin. Debated on using just EL11 and EL12 spez - that would look smart and no adapters required - built to suit purpose. However I've already started buying NOS GEC KT66, Philips Miniwatt 6CA7, GEC KT77, Tung Sol 6550 etc, so it make sense to have an amp to also use these wonderful power tubes.

Also besides EL11, I wanted to use 6SL7, 6SN7 and 12a*7. Also using tube rectification to keep it in line with the old school SET amp concept.

Sowter iron is expensive for the specific windings we're requesting but I reckon, let's do it. Finally Yamamoto sockets for a bit of indulgence and extra expense. Mundorf caps too. Not over the top but enough to make it all come together.

I'm very sure this will be my last amp.

 

[UntilThen]

I will lay out all my EL** tubes and take a photo. I have no idea how much I spend on them but they cost less than the other money sucking power tubes such as the GEC KT88.

In my opinion, the EL12 spez is right up there with the best of the other power tubes. EL12 spez are predecessors of the famed EL34. To my ears, the EL12 spez sounded a bit better than EL34 with better resolution, top end clarity and a hard hitting, controlled bass. Lovely midrange too.

 

[L0rdGwyn]

Thanks mate. It will be bigger and has more configurations than Berlin. Debated on using just EL11 and EL12 spez - that would look smart and no adapters required - built to suit purpose. However I've already started buying NOS GEC KT66, Philips Miniwatt 6CA7, GEC KT77, Tung Sol 6550 etc, so it make sense to have an amp to also use these wonderful power tubes.

Also besides EL11, I wanted to use 6SL7, 6SN7 and 12a*7. Also using tube rectification to keep it in line with the old school SET amp concept.

Sowter iron is expensive for the specific windings we're requesting but I reckon, let's do it. Finally Yamamoto sockets for a bit of indulgence and extra expense. Mundorf caps too. Not over the top but enough to make it all come together.

I'm very sure this will be my last amp.

Wow that is quite the lineup! Maybe use native sockets for you the tubes you feel will most likely end up as the "daily drivers". Sowter is expensive, but in my opinion for a custom build, it is better to go custom transformers suited to the design. Lundahl transformers are very good, but there are compromises made to allow the flexibly to wire for various applications that affect performance. If you go custom Sowter, it will be tailor-made for the best sound. Yamamoto are very expensive too, I have them in one of my amps, $50 each for five but they are very nice, similar teflon knockoffs have been disappointing. There is a Korean company called Oh's Audio that makes a similar teflon socket to Yamamoto, but they have very limited socket options (UX4, UX5, B4, B5, U6A, some other exotics), I hope some day they will expand to more common types, like octal particularly. Focus for them seems to be on very early American and European DHTs.

Anyway, I will keep an eye out for your completed amp.

 

[UntilThen]

Well thanks Keenan, that certainly makes me feel better about spending on Sowter UK transformers. In the early stage, Tomas deliberated on what transformer maker to engage for Odyssey custom transformers, specifically one power transformer and 2 x output transformers. Finally he told me about Sowter so he obviously knows they are good stuff. A Sowter choke will be too big to fit inside the chassis so a Hammond choke will be used instead. I told Tomas, whatever you say. What do I know about choke.

I don't know what will be my daily power tubes. I like them all and as most of them are 8 pins KT88 type, that's the sockets to be used. I like EL12 spez but it's the only odd man out so that will use an adapter. Also 807 tubes will use adapters. Not sure about GEC TT21. It's a gorgeous power tube but not sure if it can be used or whether I'll use it. As if I don't have enough of GECs !!!

Odyssey will be silver in looks with 2 nice meters. Transformers will be mounted on top of chassis naked. I raise my eye brows when Tomas suggested that. Ok let's forget about modesty. Let them appear naked. Such nice transformers cannot be covered. I raise my eye brows again when Tomas says let's hope Odyssey won't weigh more than 20 kgs. I'm starting to think those Sowter transformers must be Sumo wrestlers to add so much weight !

The GEC TT21.
https://www.ebay.com.au/itm/2030752...by_YicpaT2G-x3LiCwcc9m0GBW_e_OFEaAj_TEALw_wcB

 

[L0rdGwyn]

I agree show them off! I have done the same, too nice to hide, Sowter is a household name. All of the iron can make these amplifiers heavy. My main amp has three transformers and three big chokes, I break my back every time I move it I think it's smart to leave the anode cap tubes for adapters, octal sockets should give you tons of options without adapters.

 

[UntilThen]

My main amp has three transformers and three big chokes, I break my back every time I move it

That really make me laugh. My Sansui au alpha 907mr weighs 32 kgs. Finally I sold it off to be replace by the monster Kenwood KA 3300D. I told myself I'll never want to carry an amp weighing more than 30 kgs again.

Why do you have 3 chokes? What are they for? Choke holds as in wrestling lol that's all I know.

 

[L0rdGwyn]

Why do you have 3 chokes? What are they for? Choke holds as in wrestling lol that's all I know.

A choke is a electronic part used to pass direct current and low frequency alternating current, it is wire wound on a magnetic core similar to a transformer. They can have several uses in a tube circuit, but are most commonly used as filters in the power supply to remove ripple from the rectifier, aiming for nice smooth DC for the tube plate supply without 120Hz buzz of power supply ripple. My amp with the three chokes has a passive CLCLCRC power supply (this is a common way to write the order of the filter components of a linear power supply, C is capacitor, R resistor, L choke). There is one choke for both channels, then a split with one more choke for each channel, so three total.

But chokes can be used in many ways, as tube plate loads, cathode follower loads, grid chokes, all kinds of stuff, but most often as filters in the power supply.

 

[UntilThen]

Thanks for the lesson on chokes. I'm a software guy so all this is new to me. There is more to the SET amp than just point to point wiring. Everything contributes to that lovely tube amp sound I guess. That is even before we consider the different types of 1950s, 1960s, 1970s vintage tubes. All very fascinating.

 

[UntilThen]

Tomas did a mock up of how the Sowter transformer will look on the silver chassis. Together with the grey colour of Telefunken EL**, I think it will look great.

This is not a Sowter iron. Just some other silver iron for show and the wires will off course be hidden and I'm not having those 4 sockets in front.

 

[L0rdGwyn]

Tomas did a mock up of how the Sowter transformer will look on the silver chassis. Together with the grey colour of Telefunken EL**, I think it will look great.

This is not a Sowter iron. Just some other silver iron for show and the wires will off course be hidden and I'm not having those 4 sockets in front.

That is a nice looking chassis. What type of tube rectifier?

 

[SonicTrance]

That is a nice looking chassis. What type of tube rectifier?

It'll have a GZ34 for low voltage drop. Then he can play around with others like 5U4 for different, cooler, operating points =)

 

[L0rdGwyn]

It'll have a GZ34 for low voltage drop. Then he can play around with others like 5U4 for different, cooler, operating points =)

Very nice. I believe UT has a metal base GZ34 on hand, the holy grail, should be fun to play around with different rectifiers / bias points. Hopefully Sowter gets the transformers out fast! I have a custom mains transformer on order form them, about 1.5 months so far, my last order took a little under three months. I was told they were short staffed due to COVID last year, but have brought on more staff, so hopefully things will move more quickly down the road.

 

[UntilThen]

Very nice. I believe UT has a metal base GZ34 on hand, the holy grail

Not yet. My supplier has a pair of GZ34 metal base. Will try to persuade him to sell me one. I have a Mullard GZ34 blackburn factory though. Been offered a 596 JAN USAF, Mullard 5U4G, Philco 5U4G and a 5U4G from West Germany.

Already have Cossor 53ku, Mullard GZ32 x 2. Sold off GEC U52 - dang will have to buy that back.

I'll just have to wait for Sowter iron. That timeframe is not a problem for me. I'm in the queue for Tomas's amp. I'm Mr June / July at this stage. Could be Mr August. Not a problem for me. Will take the intervening time to buy my tubes.... there's a whole bunch of tubes waiting to be bought... Brimar 12ax7, Mullard 12at7 gold pins, GEC KT77, Tung Sol 6550, GEC KT88 will be last. Oh my supplier has many good 6SL7, 6SN7s...... bring it on.

 

[baronbeehive]

I raise my eye brows again when Tomas says let's hope Odyssey won't weigh more than 20 kgs. I'm starting to think those Sowter transformers must be Sumo wrestlers to add so much weight !

Maybe you need to employ the services of a personal trainer before you start lifting it lol!