Princeton Reverb AA1164 type Build..or another deluxe?

[Toxophilite]

Perhaps I misunderstood this site's intent. Should I not be here if I don't purchase things from Doug's store regularly?


He has good prices etc, but shipping costs to Canada on individual items sometimes make them cost prohibitive. the exchange rate is terrible right now too though his prices reflect that to some extent. I think shipping on that transformer would be about as much Can as the transformer itself.
All respect to Doug and this excellent site.
Also I tend to still think go-to-a--store-and-buy-it rather than 'order it online' though it is probably more practical to order it online.




I guess that's a no on my question regarding the transformers I have??

[sluckey]

There has never been any requirement to shop in Doug's store. I was simply commenting on his fast shipping. Seemed appropriate to me since your source was dragging their feet with your order. I didn't see any transformer question. I'm a straight talker so you don't ever have to read between the lines or assume I meant something different than what I said. You've been around long enough to know that.   

[Toxophilite]

True enough and I guess my question was worded in a rhetorical  fashion
here it is again


i have a couple of other small single ended transformers 3-5 watts. One measures 250ohms - 1.6ohms  the other is 185ohms - 1.2 ohmsi guess I couldn't get by with either of these . From what I've read fender reverb transformers are about 2k - 1 .2 ohms

[sluckey]

Based on that info I would not use either of those transformers.

[Toxophilite]

Well because I'm mad and impetuous I wired in the larger of the two (size and primary resistance) reverb transformers and after the usual mishaps( parts backwards, electrocution, 1meg instead of 100K resistor, ooops no coax cable connecting the reverb mixer with the PI) I got the amp going and it sounds good.


However I guess as expected , even with an SS rectifier my voltages are lowish in the power amp, 350VDC biased to 25 on the 6V6s
170 on the preamps and 180ish on the PI
Had to do some messing around with dropping resistors.
it might be a thing if I want more om pah pah to put in my backup PT that produces 375-0-375
Right now I'm maybe getting around 16watts which isn't bad.


Humourously I have reverb with the wrong impedance transformer and the 12DW7. Fine sounding reverb, not quite enough to be Dick Dale but more than enough for everyday use . Still will get the proper transformer.




I have an OT question


the VP20 schematic and instructions claims there is an 8 ohm tap and a 2.5 ohm tap (for 3 speakers)


Measuring the turns ratio on the OT (variac at 10VAC on the secondaries)
I get 30-1 on the yellow tap (300vac)
and 22.7 - 1 on the green tap (227 vac)


It seems like the yellow tap would be the one to use with 6V6s (or EL84s as the original had) with a 8 ohm speaker


While with 6V6s or El84s the green tap would be more suited for a 16 ohm speaker (or pair of 8s in series what have you)


For now I have a merette on the unknown(maybe ground) orange wire on the secondary side.
I did attach it to ground while a guitar was plugged in, right after I strummed it. and the map got noticeably quiter
strummed the guitar and unhooked it from ground and the amp got noticeably louder


Could it be a NFB tap??



Compared to the schematic 9and instructions it doesn't really make much sense

[sluckey]

Could it be a NFB tap??

Use your ohm meter to get a clue about the orange wire. Check for resistance between the orange wire and every secondary wire. Check for resistance between the orange wire and every primary wire. And also check for resistance between the orange wire and the shell of the OT. What are your readings?

[Toxophilite]

Just so the proper methodical approach and one that I probably should've taken before building...


Here's some readings in a hurry prior to rushing off. When I get back I'll desolder the black secondary from speaker jack ground (and this chassis) to properly check the shell.


So for now
Resistance between the orange wire and all the secondaries (green yellow and black) and chassis  would seem to be about .4-.5 ohms


Between the orange wire and the all the primaries (brown black red) it reads as open


As stated already(though in a couple of posts just trying to get all the info on one spot)


As far as testing for turns (with 10VAC) when the orange wire was considered as a tap and tested with the black secondary (briefly) the transformer buzzed ominously. It did the same thing when the orange wire was considered as a ground and tested with the green or yellow secondary.

[Toxophilite]

The usual crazy unconventional construction.
Seems to be working well
Probably achieving about 16 watts
Reverb works great
I found another Ot that I had kicking around. I think it's an actual hammond organ reverb driver. It seems to have the typical hammond AO sort of code A0-27311-1
500 ohms on the primaries and 1 ohm on the secondaries, seems to be working


Only issue right now is that my tremelo is making a bit of buzzy noise in time with itself, very quite but something to track down.
Now to finish up the new baffle and mount it in the old regal cabinet with the original logo so it's kind of a sleeper amp.
The usual assortment of knobs, One is a late 60s Gretsch knob off my Tennessean actually.
i have to go pick up a few more small ones.


Still don't know what the orange secondary tap is but thought I should leave well enough alone

[Toxophilite]

Here it is (mounted in the ratty little regal cabinet I had), with a friend.
I have a JBL D123 in it which sounds great of course. originally I had a lighter 12" Rola alnico speaker from an organ and it sounded really nice except it didn't have much oomph and would crap out on the bottom very easily.
The JBL is HEAVY though.

[sluckey]

 

[tubenit]

Well done!  Thanks for sharing your work.      With respect, Tubenit

 

[Toxophilite]

My pleasure, and more to the point, thanks for the help!

[Toxophilite]

If anyone is interested in hearing the one 12DW7 tube version of the standard fender reverb circuit I made some short sound clips.
Using the princeton deluxe reverb I just built with a 12' Rola speaker in it which has a pretty top end. To be fair the reverb circuit is using a Hammond AO-63 reverb driver transformer 600 ohms - 1.2 ohms  and a fender type long 2 spring tank.
Possibly the circuit could provide even more verb with an actual fender spec reverb driver transformer.
I find there's more than enough for my uses.

Amp is miked with an ubiquitous Shure 58 because it was handy.

Guitar used is 1953 Gretsch Electro 2

Amp is set at V - 1.5-2   T - 3.5   M - 1   B - 3 and the bright switch is on.

First few clips are just a few different things played with what I would consider an everyday amount of reverb set around 2

Last clip is reverb on 10 full on and appropriate music...


https://soundcloud.com/user-650789422/prd-sound-sample

[tubenit]

Hey, thanks!   I enjoyed hearing that a lot. You've got a very fun and engaging playing style.  Both your playing and the reverb sound great. 

With respect, Tubenit

[tubeswell]

I am leaving the 12DW7 in there.  I only tried one guitar with this using a semi-hollow body Tele (no f-holes) with H-S-H pickups.

Thanks for the suggestion!  I think it is a worthwhile improvement. I would not anticipate getting more reverb with the 12DW7 but getting a smoother and cleaner sounding reverb with the 12DW7...

Hi Jeff


I take it the 'AU' triode (in the 12DW7) is the one being used for the reverb driver stage? Assuming this is so, you may get even better results if you increase the cathode resistor to get a decent centre-bias on this triode. Assuming a fender RT with a 25k load resistance in Class A, this would like to see about 14v or so bias giving 6.5mA plate current, (312V* x 6.5mA, is 2W plate dissipation = ok) 14V/0.0065A = 2,153R, so 2k2 cathode resistor ought to do it. 14V bias will give you more headroom.


*I'm crudely assuming a plate idle voltage of 312 - going off the voltage notations on your schematic (and of course that was with a 12AX7 triode in there). Of course, the plate-to-cathode voltage is the pertinent metric to measure, and so in reality, you'll probably be seeing something other than 312V, but the above calculation is enough to give you a ballpark idea, and you can adjust the cathode resistance once you see where it lands. YMMV

[tubenit]

so 2k2 cathode resistor ought to do it. 14V bias will give you more headroom.

Yes, the 12AU7 side of the 12DW7 is the driver.

As always, thanks for the information!  I appreciate all that you contribute and share on the forum. 

With respect, Tubenit

[tubeswell]

Interestingly, the 'AU' triode in the 12DW7 is rated at 3.3W, so theoretically you could go even lower bias voltage

So assuming HT=312V, and eyeballing the last graph on the Sylvania datasheet, a 25k load line gives you 12.48mA at 312V, which at the 312V abscissa equates to roughly -12V (2/5ths of the way between the -10 and -15 grid curves), so that's 300V plate-to-cathode. 3.3W/300V = 11mA for maximum dissipation. 12V/0.011A = 1,090R, so that's basically 1k1 cathode resistor (to be on the safe side with your 25k RT idling at 312V). The 1k1 should be rated at 0.5W minimum.

Hotter than I first thought  

https://frank.pocnet.net/sheets/106/1/12DW7.pdf
https://frank.pocnet.net/sheets/127/1/12DW7.pdf


(PS - given the 3.3W rating, methinks a pair of 12DW7 would make a nice low power PP stage complete with LTP)

[Toxophilite]

Are you referring to tubenit's circuit or the fender circuit in my amp?

[tubeswell]

tubenit's circuit. (Sorry for the thread hijack)


But if you're going to adopt a 1-tube reverb utilising a 12DW7 with the 'AU' triode driving a Fender RT for your build, then the same sort of analysis applies.

[Toxophilite]

I've been using it for a few weeks now, It sounds great, and no smoke!

[DummyLoad]

bahaha If I hear that Johnny Depp thing one more time heads will roll!!!    He stole my facial hair...though I stole it from Errol Flynn.


In the stereo amp. Main amp (dry) - JBL D123 , Echo amp - Eminence little texas.


Amp has more than enough clean 'headroom' for this band and happily plenty for my louder rock band too.

I'm glad you liked the video
If you like the music there's another 10 videos up from the same show and more to come. Here:

 There's a fair amount of musical variety.

links broken.


--pete

[Toxophilite]

Well here's another one then

It must have something to do with this site as the youtube channel with all the videos is still there. THough looking at this one I'll have to talk to my drummer about the sync for the first shot...ooopsy something got nudged in the editing
Click on the  bold band name in the description to be taken to the channel