OT on ebay- opinions please?

[The Captain]

As Im in Uk, and scratch planning an affordable 5E3 build, transformers are very expensive from the US- can anyone give an opinion on this one? It says Fender Deluxe OT (tho no markings)- it should be perfect no? Opinions would be appreciated..
http://cgi.ebay.com/ws/eBayISAPI.dll...DME:B:AAQ:US:1

Also my other bits' plan is so far: a hammond 372bx PT (from UK), 2 EH 6v6GTs, a generic 5Y3, an EH 12ay7 and a Sino 12ax7. My speaker's a 12" Eminence legend 125 (8ohm 99db- I cant afford an Alnico Jensen) already in my small diy cab, which I hope to squeeze the lot into!

Any opinions/ advice on my choices as its my first time building an amp, again MUCH appreciated.

Thanks, Captain.

[The Captain]

Actually Ive a hunch that ebay one above is a bit crap and a hammond 125 E output trannie is better- tho ebay seller says 'it sounds great'.. but he would eh?

[matndona]

I haven't heard of this one, but the visual equivalent over at Antique Electronics (P-TF41318 ) looks the same and uses a paper winding tube as opposed to a plastic bobbin. I've measured that one up and it has the right inductance to get you down to 80Hz or so & a low leakage inductance between the windings indicating it's interleaved. Haven't used mine in a 5E3, but it drives 2 x 10's nicely in other 18W and AX84 circuits.

You may want to ask the EBay seller about the bobbin and construction.

[Bruce / Mission Amps]

If you noticed, 4 or 5 others have bought one of the 244 they still have left.
Email one of those buyers and see what they think.
Size wise, there is nothing to reference it to but it looks small, maybe a little bigger then a Princeton Reverb OT but not as big as a real Deluxe Reverb OT nor a real tweed Deluxe OT.
I can't say for sure, but it looks like a VERY inexpensive piece of cheap Chinese work to me.
It reminds me of a Weber OT or possibly one of the low quality trannys New Sensor was trying to unload for next to nothing when they were selling low quality transformers from Taiwan and nobody wanted them.
At one time they were trying to get rid of them at something like $9.00 to $11.00 each
So keep in mind that when it comes to output trannys, you get what you pay for.
By the way, a Deluxe Reverb OT has a different impedance then what is found in a 5E3 but a DR OT should still work if it is any good at all.


Check these:
http://www.tubesandmore.com/scripts/...item=P-TF22913

or this one:
http://www.tubesandmore.com/scripts/...item=P-TF41318

As mentioned by matndona... Antique Electronic Supply has good transformers, and I bet they are much better.
They are made in the USA by a well known magnetics company that totally knows what they are doing but wishes to remain annonymous, as far as who supplies AES with transformers.

[The Captain]

Thanks for those links; Im awaiting a quote from Tubesandmore.com. Ive just tried asking a few buyers of those ebay Ts- alas unable to. I think Ill ditch that idea, as suggested they do look cheap and chinese.

Bruce when are you going to open a shop in England? that'd be good! (another quote for a decent $40 OT was + $37 post, before duties/ VAT this end so over $100.. )

The only decent one seems to be the ubiquitous hammond 125E here. Any views on these would be useful. Also if used with a 372bx power T (300-0-300 I believe) anyone know what rectifier type to use?

Cheers for the help folks, Captain.

[The Captain]

Thanks to the links, Ive got a good quote from Tubesandmore for the second OT link above. I've seen a 'flexible' type PT which would be great if suitable for a 5E3-

http://www.ampmaker.com/pt03x.asp

If anyone has a mo, could they tell if this pair of Ts would work ok together for a 5E3? Ive not ordered the rectifier yet, perhaps this needs something other than a 5y3GT.

Thanks for terrific help so far, Captain.

[MWJB]

The Ampmaker PT is a bit low voltage for a 5E3 type amp at 275-0-275VAC. The Hammond PT is also a shade on the low side, but not necessarily a problem if you're happy to use a 5V4/GZ34 rectifier? Will the stand-up style Hammond PT fit in your "small" DIY cab?

As far as OTs go why not try TAD in Germany for a US made Tweed Deluxe OT, a shade over £50, plus shipping? They can usually turn round stuff in around a week to the UK.

Barry Vyse at torresamps.com in Pinner has a generic 25W, 2x 6V6 OT with multi tapped secondaries at £43. I have used one in a prototype build and it sounds great, they don't have the specs listed in as much detail any more but I seem to recall it has an 8.5K primary (close to a 5E3).

[The Captain]

Ah- I think this bit caught my eye from the Ampmaker spiel..

* The 0-275V winding gives typically 360V when rectified - designed for octal power valves (EL34, 6L6, etc) in more powerful SE amps (15W or so). This also has 160mA available, so it's also perfect for push-pull amps with lower-power valves, such as the EL84 and 6V6.

Is that definitely too low powered? or is that perfect for push-pull amps with just ONE 6v6..
MWJB, does your reply imply I can use this PT effectively by using a different rectifier tube, or is that just the hammond you refer this to? I wonder also what different rectifiers sound like..

Im getting the chassis and valves from TAD so Ill check out that OT. thanks Capat.

[TD_Madden]

actually, 360 sounds about right.

[MWJB]

I would only expect to get 360vdc B+ if the 275VAC winding was rectified with solid state diodes. The ampmaker PT does not appear to have a 5v rectifier winding, so you are stuck with SS rectifiers or Weber copper caps. A WZ34 would probably do the trick.

I was suggesting that the Hammond was closer to spec., however I don't know how easy it would be to fit the Hammond in the 5E3 chassis?

[The Captain]

I would only expect to get 360vdc B+ if the 275VAC winding was rectified with solid state diodes. The ampmaker PT does not appear to have a 5v rectifier winding, so you are stuck with SS rectifiers or Weber copper caps. A WZ34 would probably do the trick.

I was suggesting that the Hammond was closer to spec., however I don't know how easy it would be to fit the Hammond in the 5E3 chassis?

Ive found a good OT now. As for a ~240v PT tho..
Cheers for that MWJB- I asked Ampmaker who said its not suitable for a 5E3 type (is it only a one 6v6 config? something to that effect) so that one's ruled out. Ill damn well squeeze the lot in thats for sure however big! I tried Hoffman, & found he does a decent well priced 240v drop in 5E3 PT- great: his (excellent detailed) site has an Int. shipping bit, but no indication of 1 trannie to uk. So I email & he says.. 'I don't give quotes' !? so how the hell do I know what the post cost is? SO annoying.. As an idea for US folks here- a quote for a TAD PT = $240 posted from germany. eek!

[Bruce / Mission Amps]

I wonder if the TAD Deluxe PT is really a MOJO 761EX PT...

http://www.mojomusicalsupply.com/ite...8&id=MOJO761EX

that is the same PT I use in the 5E3 kits sent to Europe.
I think the 6-10 day shipping/handling for a 10lb-12lb box to the UK cost about $55.00.

[The Captain]

Thanks for the tip Bruce- Id be inclined to buy a PT export v from yourself due to your general help with folks on this forum, but the post cost + duties make it too much from US I think. Choices from uk are zero, and from TAD pricey too. A 2nd hand one would be the only affordable option now it seems.

[barfoden]

The ampmaker 275V power transformer is ok for a 5e3 build, but only if you use diode rectification for a B+ of around 350-360V and maybe slightly lowered the screen dropping resistor or preamp dropping resistor to increase the voltage downstream.

I saw a guy online make a 5e3 with a 260V/100mA power transformer with no 5V AC secondary. He used diode rectification, had a b+ of 340V and a plate voltage of 328V. He used a 270 ohm bias resistor and a 10K dropping resistor instead of the 22k in the original to keep PI and preamp voltages the same as the original 5e3. It worked out great for him. He built it as a really small head running through a large 1x12 with a cannabis rex speaker.

Other amps "similar" to a 5e3 (Dearmond R15) used lower plate voltage (330-340V) with a 250 ohm bias resistor and a smaller dropping resistor (2.7K).

I have seen a demo of the fender reissue 57 deluxe and when turned up it sounded like it was imploding, sagging like crazy.. This is mainly due to using a 12ax7 in V1, having huge coupling caps (0.1µf), no grid resistor on the cathodyne, a slow rectifier and a small 16µf main filter cap.

I do not think the 5e3 will never be a tight amp due to cathode bias and no negative feedback, combined with a bass heavy circuit.

My 30 watt Laney LC30 with a G12H was never really a tight amp on the bottom eventhough it had a 100µf main filter cap. The hot cathode bias with low voltages and no negative feedback, and small OT do not give rise to a tight amp. The celestion G12H might need some more damping (global NFB) to sound tighter around its resonance peak (85Hz).