Need help with building the right amp ( update)

[xtian]

Separate filiment transformers are not too expensive. Tubesandmore.com. And you can just as easily get bias voltage from your HT coil.

[sluckey]

I just realized , if I want to have a grid based biasing on 6V6 I need to have a transformer with 50V bias tap, right?

No. Just copy this Marshall bias supply. You may need to change the value of the 220K to provide the correct voltage range for your circuit.

[img1304]http://el34world.com/charts/Schematics/ ... 20EL34.gif[/img]

Or you may prefer the similar Fender Princeton Reverb bias supply...

http://el34world.com/charts/Schematics/ ... _schem.pdf

[chikov]

Good, I will be studying all this info for a couple of days. I have been working on organizing my work bench - changing it from guitar shop into an amp shop.

[IMG:640:480]http://i409.photobucket.com/albums/pp171/alexjohnne/4deb455b-c28b-403b-8ef7-1211ba794d98_zps9dvzrmve.jpg[/img]

I will organize my electronic components next, then I will be buying some parts from Antique electronix. A quick question, how many amps should I have on my filament transformer?
...and what is a good place to buy tube amp components (price wise too)?
I know of tubesandmore.com - are they good?

[chikov]

I started to put together BOM and got a little overwhelmed - i have at list 3 schematics in front of me (i.e. AA 964, AB 763 and derivative from aa964). Some parts vary, modified and substituded... I am not sure what to do. May be i should build basic AA 964 without the tremolo and then add on modifications?

[chikov]

Will this transformer work for my filament 6.3 AC supply?
https://www.tubesandmore.com/products/P-T166N6


Thank you.

[chikov]

one last thing, I have been studying my Seeburg output transformer in order to see if I could use it for my Princeton amp build.
http://arcarc.xmission.com/PDF_Jukebox/ ... ma1-l6.pdf

I applied 30 Vac to the primary inputs and read on the secondary, between ground lead and the first 1.2V and between the ground lead and the second wire about 0.85V. Between 30V and 1.2V we get 25 WR. So, at 8Ohms impedance on secondary I get about 5000 (not too useful for needed 8000 for 6V6 tubes AB). If i use the other lead with .85 Voltage I have ratio about 35.3 and that puts me at 9,800 impedance on primary... wouldn't it be too much?

[xtian]

Will this transformer work for my filament 6.3 AC supply?
https://www.tubesandmore.com/products/P-T166N6

Looks good.

[chikov]

Will this transformer work for my filament 6.3 AC supply?
https://www.tubesandmore.com/products/P-T166N6

Looks good.

Thanks for advice, I added it to my shopping card.
I was hoping to get some advice on the output transformer... After studying it for a little more discovered that chances are the output transformer is made for 16 and 8 ohms speakers. Because according to the rules, the voltage on the secondary should increase by square root of 2 from 4 to 8 to 16 ohms. My two readings were .85 V and 1.2V - exactly matches the theory. Plus if you calculate 16 ohms times 25 (ratio) squared equals to 10,000 and the next tap (8Ohms) gave me about 35.3 ratio. If you square that and times 8 it equals about 9,980... Good. But the question is, will it work with a pair of 6V6s with the output transformer generating about 660 Volts (330V to the tap on B+)?
Anybody?

[chikov]

Well, I did not realized how much Reranch forum spoiled me - for every question I had I got 3-4 answers on average... But I also realized that this forum is not for the boys but for real men - not getting an answer made me study harder, watch a ton of you tube videos, read Gerald Weber books in depth, watch some of his videos I have over and over again. I am finding some of the answers along the way and I will find more once I will start putting the amp together from scratch. I am placing my order tonight - building slightly modified blackface Princeton to start with.
One thing I can not find is the value of that diode on the fixed bias circuitry. does anyone know what it is?

[TUBEDUDE]

Don't listen to Gerald Weber too much. Look at the books from London Power, Merlin Blencowe, the Radiotron Designers Handbook etc. Randall Aiken's site, just to name a few. Use the search function on this site. There are many knowledgeable folks here, we all build amps and some manufacture them for sale. Ask questions, but a bit of research first might provide an easy answer to avoid being tiresome.
a diode used to develop bias voltage needs to have a higher peak inverse voltage higher than the voltage being rectified, and multiplying that by at least 2, for safety, is a good practice.
the common 1N4007 will do fine.

[chikov]

Thank you, tubedude, for some info on other good resourses. I guess I went for Gerald because he had couple of books and videos that were written in simple language and straight down to the point kind of style... I will study other stuff too, I know I must if I am to become a good tech in the area of tube amps. Can you explain, in general, what is the problem with Gerald's stuff?
That brings me to my nest question. Gerald is a big fan of a totem pole cap stack before the bypass switch. He suggests to put the two 220f 350V caps in series and use two 220K resistors as a voltage divider. He says it helps to filter DC even better, keep things in tune and keep the ripple current away... Do you agree?

[TUBEDUDE]

Gerald has some acquired knowledge but he has some strange ideas that may be dangerous. One was a cure for oscillation that involved tying the shield of a wire going to the grid to the plate. It provides a bit of negative feedback that will work, but the full plate voltage is on the shield! There are other opinions but I'll let those members tell their own tales. The totem pole is a time honored technique. I like it with B+ over 350 volts because it gives a cushion against high voltage spikes, as 500V caps are the highest commonly available. The resistors assure the voltage is divided equally between the two caps.

[Firestorm]

Gerald likes stiff power supplies, hence the 110uF for the main filter. But there iconic amps that are seriously underfiltered. Yes, they tend to produce ghost notes when pushed, but that's part of the "charm."

[chikov]

I guess I will A/B both the Totem pole, and the regular capacitor - see what sounds better to my ear. That brings me to another "big" question... I salvaged from my Seeburg amps 3 choke transformers (funny thing is that the smallest one reads 153 ohms, middle one 103 ohms and the biggest one only 95 ohms). what are pros and cons of using chokes vs resistors in the B+ supply?

[John_P_WI]

Chokes have inductance, resistors don't - in this context. Study R C and L C circuits and understand how L C circuits can reduce ripple.

See which one will give you the lowest voltage drop for a given current for the "same" amount of filtering.