Root 666

[mcrracer]

I am considering building a "Root 666" with KT66. The original appears to have a UL OT To the gurus here...how much would performance be compromised by using a regular OT and tapping off a node on the B+ rail for the screens? Has any one built one of these? Impressions? Thanks

[Structo]

Not sure but I have a print of that amp that gives the part number.

Cin Tran 3232 30-9912

I don't know what the specs are but Hammond makes quite a few ultra linear OT's.

I don't know why it would make a difference because if the voltages on the schematic are right, the plates and screens are about equal with the screens actually being .1 v higher.

I think Cin Tran is out of business, their domain name is for sale.

If a guy could figure out the specs, there is probably a Hammond that will work.

Looks like a Hammond 1650PA pr 1650NA would work.


http://www.hammondmfg.com/1608A.htm

These OT's have that funky secondary wiring so be fore warned.
I know that AES has impedance switches made for these.

[chopstuck]

Since the RT 666 and the Z 2.8 are so similar I decided to build the one in between. It's an amp with a choke with a bit higher V+ that likes both 6v6 and 6l6's. It's made with a lot of recycled parts and iron. It really kills with 6V6's and a Deluxe (Schumacher) OT and an 8 ohm load. I have read somewhere that the UL OT ads very little character and plays louder and cleaner. Some don't care for it. I listened to both amps in a Guitar Salon and wasn't impressed with the RT either. Sounded a bit like a Fender Showman. Just too loud and lacking any real character.

[stoo]

You could always add some NFB to make up for the non-u/l.

[mcrracer]

Thanks, your schematic is a little better than the one I had. Now I wonder if I have to go to the good doctor to obtain these trannies. I will try searching and see what comes up.

[M Fowler]

I just used the JTM 45 iron set rather than the UL transformer. No bias tap on the PT so I borrowed from the seconary supply and used a 220k resistor.

The amp sounds fantastic and one of my friends favorite to jam on.

Mark

[M Fowler]

The Dr will not sell you any trannies I have heard about that on is forum.
Cin-tran was bought out and still operating.

[M Fowler]

One more thing the schematic correcty shows the 100pf parallel with the 91k and 82k but on the layout it is omited.

[mcrracer]

Mark, did you use the suggested caps? The 715P ODs?

[funkmeblue]

anyone know the primary impedence the good doctor used for this cin-tran output? It's suppose to be based on a leak tl 25 plus and it uses a 7k http://44bx.com/leak/transformers.html

[topbrent]

Here is the layout and gutshot for the Route 66.

[mcrracer]

Thanks much for all of the extra info guys.

[M Fowler]

Yes I did and I had to look back on my old pictures to answer that.

I modified this layout to show the 100pf added.

I used Mojo JTM 45 PT 350v-0-350v
Mojo JTM 45 OT 3.4k 2,4,8

Mark

[M Fowler]

Another interesting schematic used 12ax7 instead of EF86 and 6.6k OT.

The other data shows to use 8k OT.

[chopstuck]

Mark, Here's how mine turned out. It's made up of Hammond organ iron, a Watts turret board and an old Judybox chassis. I use 22g teflon wire for all the leads. Wire looks small but the insulation is paper thin. Low $ but a lot of time invested here. You wouldn't know it by looking at it though. I may try a trem circuit in there eventually to use the extra tube. Now I have a mismash of coupling caps. Are there any opinions on the ETR chicklets ? I have been getting them from justradios.com and they seem OK. But I'm always looking for a little better.