caddisgeek Posted June 17, 2014 Posted June 17, 2014 Where's djb? I feel somewhat cheated and decieved 2
Bronal Posted June 17, 2014 Author Posted June 17, 2014 It's an OTL preamp that uses either 45s or 2A3s and was produced by DIY Hi Fi Supply from about 2010 to 2013. Can be very fiddly to set up correctly, but when done so is one of the best preamps you'll ever hear.
Sir Rab of Everest Posted June 17, 2014 Posted June 17, 2014 What, no Mills resistor on the Coleman boards? ;-)
Bronal Posted June 17, 2014 Author Posted June 17, 2014 What, no Mills resistor on the Coleman boards? ;-) Yes, on my other one!
Bronal Posted June 17, 2014 Author Posted June 17, 2014 Does anyone know if any Duelund caps would fit inside a Tram?
henry218 Posted June 17, 2014 Posted June 17, 2014 (edited) u can check the sizes at hificollective.co.uk edit: sorry, should be partsconnexion, hificollective doesnt have dimensions for duelund but they do for others Edited June 17, 2014 by henry218
Steve M Posted June 18, 2014 Posted June 18, 2014 (edited) Bronal, I have seen Duelund Casts fitted to replace the green input capacitors. There is a long thread on DIYAudio about the mods. Agree on the sound, superb. Steve. Edited June 18, 2014 by Steve M
Sir Rab of Everest Posted June 18, 2014 Posted June 18, 2014 (edited) I use Duelund Alexander's in mine due to lower cost and VSFs probably won't fit. But I'm eagerly awaiting reports on the new Duelund caps which are said (by Duelund) to provide sound between VSF and CAST at the price of Alexanders approximately $130 ea) and the CAST form factor. Might take the plunge soon. Edited June 18, 2014 by Sir Rab of Acoustat
sjs Posted June 18, 2014 Posted June 18, 2014 What, no Mills resistor on the Coleman boards? ;-)there are! but you cant see them from the photo as they are behind the Amtrans caps.this amp is setup for 45 so lower wattage smaller Mills are used
sjs Posted June 18, 2014 Posted June 18, 2014 I use Duelund Alexander's in mine due to lower cost and VSFs probably won't fit. But I'm eagerly awaiting reports on the new Duelund caps which are said (by Duelund) to provide sound between VSF and CAST at the price of Alexanders approximately $130 ea) and the CAST form factor. Might take the plunge soon. check out the Dueland OEM Cast at Acoustic Dimensions in the Netherlands, excellent prices and excellent service in my experience
sjs Posted June 18, 2014 Posted June 18, 2014 I really like the VSF and Cast but find the Alexanders to be a bit overly warm side of neutral for the Tram, which is why these units have the Robert Hovland and Audyn True Copper caps fitted as they balance the Tram better for me. Ymmv ;-)
sjs Posted June 18, 2014 Posted June 18, 2014 And this was the other Tram2 I worked on. This one was setup for 2A3.
sjs Posted June 18, 2014 Posted June 18, 2014 Both of them came to me having been originally built by somebody else and I just did the mods. They are both pretty similar sets of mods: - earth lift switch so audio circuit can be grounded if required - Tram2 "floats" as standard - X and Y filter caps on mains inlet - screened mains cable - audio circuit resistors replaced with Tantalum film, either Shinkoh or AN depending upon availability - shunt mod to volume control - coupling caps replaced - 45 unit with Audyn True Copper 1.8uF on output, 2A3 unit with Robert Hovland 0.1uF input and 1.0uF output - resistor network on output replaced by single 1M0 - tant film in 45, Amtrans AMRG in 2A3 unit - pre is now setup with a single output to drive power amps with input impedance of about 50K or above - 25 turn trimmer in CCS to make setup less painful and reduce drift problems - Rod Coleman regs fitted, including Amtrans cap and Mills power resistors as recommended in DiyAudio thread - regs fitted to custom heat spreader, then onto chassis - Raw DC supply for Regs uses 10,000uF 63V and 40V BHC ALS30 caps and Schottky diodes to form bridge - the "optional" electrolytic cap in the ht supply was removed, it wasn't needed for either amp in my system, and it sounds better when removed After all that, I would say I personally slightly preferred the 45 unit, it was cleaner and more finesse and inner detail, but I guess bronal will be able to give us chapter and verse when he puts them head to head
caminperth Posted March 5, 2016 Posted March 5, 2016 (edited) Another Tram 2 - looks a little different to the others? I believe it was a factory build. Also located the manual here - http://www.diyhifisupply.com/files/Tram2R1.36.pdf Explains most things well - though I can't work out exactly which pins to check the 2A3 heater voltages on. Closer pic below. Sent from my iPhone using Tapatalk Edited March 5, 2016 by caminperth
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