What transformers to use?

[analogjunkie]

So I have found a layout i am comfortable with here
[img1154]http://bad-domain/DumbleLite/DumbleLite16x8Layout3.JPG[/img]

Obviously a common one, but it seems to be the most simple layout I could find for my first build and I can modify the pre amp to taste. Now, I was curious about the transformers, specifically the power transformer. I know that Ford has the music man 700 volt tranny in 148, would it be possible/beneficial to use such a transformer in a 50w model? Or should I go with an old fender transformer? Maybe a new production Heyboer reproduction of one of the two? This is the only step that I am a bit cloudy on.

Your advice is greatly appreciated in advance.

[dogears]

I'd change a few things on that layout.

1) Make sure you do not ground that last lug of the presence pot. Very important.

2) Use 220/150K plates on both the clean and OD, with 3.3/2.2 cathode resistors. 4.7uf on all stages.

3) Use a choke (RF has choke). Or if you must use the resistor, then use 250 ohm or 300 ohm. Dropping string with 450V or so on output plates, should be 3K, 22K, 2.2K

4) Use a 110K/120K plate resistor PI setup with a 10K trimmer between. With .1uf couplers.

5) Use 330pf treble cap. Or a .002 PS Orange Drop feeding the 390pf disc.

Robben does not have a Music Man setup in 148.... He uses 4 ohm Fender Twin iron and power tranny. Plus the above ^^^

[analogjunkie]

Thanks Dogears.

I was planning on using a choke along with a tube rectifier in place of the solid state as I am not looking to straight clone 148. I could have sworn I read he used a music man set up.

Also, for the filtering I notice many builders using several smaller radial lead caps, what are the benefits here? AND will using an over sized PT stress the need for 3w metal oxide resistors on the filter grid? Are there pros/cons/any changes needed if I use an oversized tranny on for the PT/OT?

[Structo]

Scott are you now recommending .01uF couplers on the PI output to power tubes?
With 6L6?

BTW, that is basically the D'lite version of the ODS.
Decide which power tubes you are going to use before selecting power trans and OT.

[analogjunkie]

I was going to use 6L6 tubes.

Why such a low value for the PI coupler caps? I thought HAD always used .1 or .047 depending on the other variables.

Still searching- ready to place my order today for the trannys, but will wait to hear some more responses.

[Structo]

Thanks Dogears.

I was planning on using a choke along with a tube rectifier in place of the solid state as I am not looking to straight clone 148. I could have sworn I read he used a music man set up.

Also, for the filtering I notice many builders using several smaller radial lead caps, what are the benefits here? AND will using an over sized PT stress the need for 3w metal oxide resistors on the filter grid? Are there pros/cons/any changes needed if I use an oversized tranny on for the PT/OT?

The radial cap version of the power supply is the later filtering that HAD used when he moved to PCB's for his power supply.

I would think it provides better filtering due to more caps but may lead to a much tighter feel and bass.
Seven caps in the old style and ten in the pcb one.

With you planning on using a tube rectifier you are bound by design limitations of the rectifier tube you use.
Most tubes have a maximum value for the first reservoir cap in the filter that the tube sees.
So the older eyelet board supply filter might be a better choice and I think as well as cheaper to build.

Most tube rectifiers shouldn't have more than 40uF on the first cap.
You can also use a switch to go between a choke or resistor to provide the two different types of supply.

The amp will only draw as much power or current as it needs.
For a 50w amp and power transformer that provides 250ma on the HT winding should be enough and 5 amps on the 6.3vac heater wind should suffice.

3 watt metal oxide resistors are a good thing to use in the power supply.
They are much smaller than years ago and are also flameproof which makes them desirable.

For good quality transformers check out Magnetic Components, they are made in the USA and have reportedly been very good at a good price point.

In my 50w version I used a Fender Prosonic 50w output transformer which has worked out well. Angela sells them.

Many feel that vintage output transformers add to the "m0jo" in the tone. It has been a point of contention sometimes but it certainly wouldn't hurt a thing and they seemed to be built very good back in the day when everything was tube powered.
So if it has survived 50 years then it should be a good one.

[dogears]

Whoops! Thanks... Meant .1uf

Although there are some great sounding amps with .05 there.

Scott are you now recommending .01uF couplers on the PI output to power tubes?
With 6L6?

BTW, that is basically the D'lite version of the ODS.
Decide which power tubes you are going to use before selecting power trans and OT.

[dogears]

Me bad. .1uf

Typo

I was going to use 6L6 tubes.

Why such a low value for the PI coupler caps? I thought HAD always used .1 or .047 depending on the other variables.

Still searching- ready to place my order today for the trannys, but will wait to hear some more responses.

[dogears]

RF uses regular old Fender Twin iron. So, if you want the RF thing, this si the only choice.

The older and used real stuff, would be a bonus.

I was going to use 6L6 tubes.

Why such a low value for the PI coupler caps? I thought HAD always used .1 or .047 depending on the other variables.

Still searching- ready to place my order today for the trannys, but will wait to hear some more responses.

[analogjunkie]

Now, here is a curve ball- what If I wanted to do a 4 6v6 style? Would the PT/OT make a difference?

[Structo]

Whoops! Thanks... Meant .1uf

Although there are some great sounding amps with .05 there.

Scott are you now recommending .01uF couplers on the PI output to power tubes?
With 6L6?

BTW, that is basically the D'lite version of the ODS.
Decide which power tubes you are going to use before selecting power trans and OT.

Heheheh, you had me worried there for a moment.
I had just ordered some new orange drops trying to fix some fizzies in my amp.

I may have to try .05uF sometime.
This amp definitely has a lot of bottom end when cranked up.
But for low volume playing the .01 works fine.

[analogjunkie]

Now, here is a curve ball- what If I wanted to do a 4 6v6 style? Would the PT/OT make a difference?

Still waiting on a response for this, I would really like to do a 4x 6v6 thing w/ tube recto.

Could I theoretically use a 40w power and 40w output?

[analogjunkie]

as in the 40w heyboers they sell on the weber site? Or would I need a certain style PT? I would basically just be bridging the sockets from the PT like you would a 4x 6l6 or el34.

Help much appreciated in advance.

[talbany]

Now, here is a curve ball- what If I wanted to do a 4 6v6 style? Would the PT/OT make a difference?

Still waiting on a response for this, I would really like to do a 4x 6v6 thing w/ tube recto.

Could I theoretically use a 40w power and 40w output?

I've built quite a few of these.. Our Rick Derringer Model HRM has them..
We use a 50w Mercury Mag Marshall style OPT and Fender 50w Bassman power.. There is nothing like them when you can push them... SING!! like a bird..
But if your chasing the RF tone I would stick with the 6L's..Keep in mind if you do decide to do 4X6v's using the Bassman power you have to use the JJ 6V's as these can take the 450V...You would be surprised at how loud a 4X6v amp can get (450 on Plates Zing)..If you decide to go there PM me and I'll be glad to give you some other tips on setting up the amp w/ 6V's
The other cool thing is you can pull the 4 V's and stick in 2 6L's or 34's or 66's... Wired right of coarse..



Tony VVT

[jelle]

~Tony,

Are you still with VVT?

jelle