Fender Pro Reverb UltraLinear (70w)

[jelle]

Glad you found it!

Good luck with the recovery, health issues ate a pain!

[gui_tarzan]

So I guess my next question would be what transformer would you guys replace this with? I looked at all the usual suspects but the UL Fender transformers are much harder to find than a standard trans. Mercury is the only vendor I've found a direct replacement and they want almost $300 for it. I don't think this amp is worth more than $500 or so, maybe $600 on a good day.

Realistically, the twenty or so watts difference won't make a whole lot of actual dB difference and I think it would sound better based on what I've read. What do you think?

[jelle]

I would contact Heyboer, or place an add for a replacement. Many guys yank these out of amps because they are this weird UL stuff, and that ain't blackface man, so it is bad and stuff.

Yeah.

[rooster]

Hammond makes plenty of ultra linear tapped OTs, cruise their site. They are half the price of MM.

And I'm also glad you got this handled. I wish you a speedy recovery from your surgery, as well.

[jelle]

This one should work. 4 ohms too. Also 40W to 30 Hz.

http://www.hammondmfg.com/pdf/EDB1650HA.pdf

[martin manning]

In hindsight a good test would have been to disconnect the CT from the power supply and see if the strange voltage readings along the dropping string came back to something more reasonable. That might still be a good thing to check, perhaps using a Variac to keep the plate node down to its normal operating level.

I think I would want something bigger than a 40W OT as a replacement.

[gui_tarzan]

Good advice.

I just heard back from the customer and he's not concerned with keeping it stock and said I can change out the OT for a non-UL if it saves money. And that would save money. I also emailed Heyboer last night before I posted and I'm waiting to hear back from them, but I've got a couple of non-UL transformers from them right now so I might see how they sound with the current speakers and circuit.

His main concern with the amp aside from it not working was that it always sounded harsh, which definitely won't go well with the acoustic body electric that is all he plays these days. My initial recommendation was to get this working and sell it, then buy an amp that works well with his acoustic. I still think that's the best idea.

[martin manning]

The thing is you don't have a dedicated screen node in the power supply, and the extra effort and expense required to add one would have me leaning toward just replacing the UL OT. If they have seen this OT before, perhaps a replacement is a available from Heyboer at a reasonable cost.

[didit]

Using google search with "013897 pro reverb" terms, among other stuff, I find this http://www.tubeampdoctor.com/product_in ... NE5qF4dz11.

If you give Heyboer and/or Magnetic Components the impedance specs (4.4K primary with 80% UL) and mounting dimensions they can build a direct drop in. Interesting possibly more affordable and accessible alternatives could be dynaco a470 clone or even the EM0720 here http://rjguitars.net/Edcor_Output_Transformers.html. RJ Edcor has slightly higher primary impedance and you'd need to use both sets of taps for the UL connection. This should have negligible impact and might even improve sonics.

Best .. Ian

[M Fowler]

The Hammond 1650KA is 50w UL 3k4 primary with 4/8/16 secondary but price is $135 on Digikey or Mouser. Not available at CEdistribution.

The 1650K is UL 50w but has the weird wiring on the secondary but probably would be ok and is available at CEdistribution. $118

Mark

[pdf64]

I think those Hammonds may not be best suited to this application; the Fender 'UL' OTs were tapped at 12.5%, rather than 40%, so an off the shelf Hammond may not equivilant to the stock part.
3k4 is rather below the best power impedance, and with the high VB+ of these amps, may result in the 6L6 overdissipating.

[didit]

I think those Hammonds may not be best suited to this application; the Fender 'UL' OTs were tapped at 12.5%, rather than 40%, so an off the shelf Hammond may not equivilant to the stock part.
3k4 is rather below the best power impedance, and with the high VB+ of these amps, may result in the 6L6 overdissipating.

Agreed. After some quick envelope scribbling RJ's EM0720 (5.2K primary using the 4.3K for ~80% screen tap) at all of $75 seems a reasonable choice if direct replacement is too expensive or too much hassle/delay.

Best .. Ian

[Stevem]

Just also note that while these Amps will never do there Fender rating of 70 watts of pristine clean power, they will do 63 watts with strong outout tubes so a 50 watt Rated OT is gonna be on the iffy side of holding up!
If it's a 2-12 amp and you can find a good used TR OT you can ditch the UL ( you need to come up with a screen supply as posted) and wire the speakers in series for the needed 16 ohm load that OT wants to see!

[pdf64]

That EM0720 is only 35Watts? I'm sure it's overbuilt but...

(5.2K primary using the 4.3K for ~80% screen tap)

I think that the UL 40% is 40% turns not impedance, so the 4k3 taps would be a mile off, basically triode operation.

How about the Edcor 4k2 UL : 4/8/16 https://www.edcorusa.com/cxpp60-ms-4_2k
or 6k6 UL : 4/8/16 https://www.edcorusa.com/cxpp60-ms-6_6k
Not ideal but a better $

[cbass]

I think for it ratings you have know what bandwidth they are rating it at a 25 watt ot rated from 20 to 20,000 hz will be huge compared to one rated from 70 hz or something.
I don't think I ever paid much attention to the size of the ot s on the ul fenders but I'd be willing to bet that 65watt edcor is physically much bigger than the stock ot.