Fender rverb trafo with different value!!!

[grtamp]

as possible that these transformers have different values ​​having the same code 125A20B?

[Stevem]

Not for the standard black and silverface amps, it should be rated to drive a 8 ohm reverb pan.

[Firestorm]

One is 29K into 8; one is 22K8 into 8. Two manufacturers' take on it and pretty close. I've never measured an original one. Anybody?

[Phil_S]

Not measured, but generally what I recall reading is that primary = 22.5K which is an insignificant difference from 22.8K. I can't see why the 29K was made, but also can't see where it would make much difference. It is being driven by a triode. Triodes tend to be very forgiving of primary impedance.

We are looking at a 3.5W transformer. I seriously doubt the triode driving it develops that much power. I'm having difficulty imagining the circuit develops 2W. So, I am thinking 29K vs 22.8K isn't significant.

[ampgeek]

Hmmmm....the cited impedance ratios differ by over 20% which would get my attention. Not sure if it would make a huge difference in performance though as Phil implies (but with different values).

NSC=New Sensor Corp.?

~10 euro cost difference nears my "cost consciousness" threshold depending on the amp project being contemplated.

Flip a coin to decide which to buy?!?

Actually, I would go with the Hammond and pay the extra cost solely based on experience with their product.

However, I would love to hear any available feedback on NSC.

Cheers,
Dave O.

[Stevem]

If you ask me what matters most here is that since its a single ended OT, than having the proper air gap in the core and if the OT is bigger in mass by a tad( as in 3.5 watt rated) that is better in regards to saturation and should make for a better drive signal.
That being said, I would trust Hammond to use good core iron than a off shore brand!

[bruce egnater]

A transformer doesn't "really" have a specific impedance of it's own. The primary impedance is determined by the load. It is a ratio, not an absolute value. In this case, if you connect the 8 ohm pan, instead of 4 ohm, the impedance that the tube sees will probably be in the "mid 20K" range.

[VacuumVoodoo]

I'm using this nifty multi matching transformer from OEP in UK for all reverb drivers in my own amps as well as service replacement:
http://www.oep.co.uk/pdf/N35A002F%20issue%205.pdf
RS-components is EU distributor.

[Phil_S]

This is a bit off the topic, but I have seen several Euro-origin transformers with solder terminals instead of wire leads. This strikes me as a big improvement. I am one of those people who hates to cut the leads for fear of making them too short. Solder tabs solves the problem because whatever you solder to the tab is always the right length. I wonder why we don't usually see this on US produced or on Hammond (Canada)?

[Jana]

I much prefer the leads instead of solder tabs. Unless all the tabs are on one side of the transformer, and the transformer is mounted through a big hole in the chassis, it is a big safety issue. I don't like the idea of having those tabs, which carry high voltage, exposed on the top of the chassis. Yes, you can put shrink tube on them, but there is still a small portion that you just can't cover with shrink tube. Give me the bell ends with insulated leads any day.

[NickC]

I much prefer the leads instead of solder tabs. Unless all the tabs are on one side of the transformer, and the transformer is mounted through a big hole in the chassis, it is a big safety issue. I don't like the idea of having those tabs, which carry high voltage, exposed on the top of the chassis. Yes, you can put shrink tube on them, but there is still a small portion that you just can't cover with shrink tube. Give me the bell ends with insulated leads any day.

I agree 100%. Maybe even 200%.

[VacuumVoodoo]

There are dedicated safety covers for both lug sides to attach if you plan on mounting the transformer externally.
I usually install the reverb transformer inside the chassis.