12ax7-ecc99 tube amp

[DUY1337GUITAR]

UGGGHHH Now I really want to build one... but I have to buy a new big amp before the next talent show....  It's okay, I'll do a sharp tug on my hair everytime I get distracted because of wanting to build this.

[alternative84]

I hosted the photos in photobucket, this is the album:

http://img21.imageshack.us/slideshow/webplayer.php?id=dsc02932c.jpg

[geertjacobs]

Nice build, very tight.
You may want to put some shrink-tube (or what's it called) on the OT taps though.
I've been zapped by not doing it on one of my builds.

[frequencycentral]

I hosted the photos in photobucket, this is the album:

http://img21.imageshack.us/slideshow/webplayer.php?id=dsc02932c.jpg

Aah, very nice build! Thanks for taking the time to rehost the photos. 

[Brymus]

I hosted the photos in photobucket, this is the album:

http://img21.imageshack.us/slideshow/webplayer.php?id=dsc02932c.jpg

SUPERB I like the way that looks! So compact and yet clean looking,I like the way you made the bridge rectifier.

[alternative84]

SUPERB I like the way that looks! So compact and yet clean looking,I like the way you made the bridge rectifier.

Thanks . I took as a reference the FcKw's build, and tried to fit the power jack, so I had to "compress" the bridge rectifier. It's a very small box (Hammond BB type), but is worth the effort, it's tiny!

[FcKw]

Hi,

sorry for my late response but I moved to another home in the last weeks and the internet is just right back up.

@alternative84
nice to hear that you made it and some nice documentation you got there! I like the power jack, I thought I would get some space problems with it, but you actually did it. How would you discribe the differences between the 12AX7 and 12AY7 in this circuit?

@Brymus
The toriodal is this one HERE and thats where I got it.
The specs are: Primary 230V, secondary 185V 0,04A and 6.3V 1,4A

Nice you liked the video, actually it's my girlfriends album and it just happend to be there on the pictures/videos.

Patrick

[armstrom]

Not do dig up an old thread... but has anyone had any luck finding a similar toroidal transformer with a 117V primary? That transformer seems to be made by a company called Multi PCB in Germany: http://www.multipcb.de/eng/sites/pool/index.html . However they do not have an English translation of the pages related to the transformers. My German is a bit lacking (think nonexistent) and machine translators don't seem to handle the navigation of the site... Perhaps they offer a comparable transformer (in terms of size, weight and electrical specs) with 117V primary ? Anyone speak enough German to figure it out from the site?

[Ben N]

Hi, alternative84, eautiful b buil (and nice sound, Patrick.) Are those 1/4 watt metal films? Do they get hot? They look like they are going to get eaten by those massive old carbon comps.

[puretube]

Not do dig up an old thread... but has anyone had any luck finding a similar toroidal transformer with a 117V primary? That transformer seems to be made by a company called Multi PCB in Germany: http://www.multipcb.de/eng/sites/pool/index.html . However they do not have an English translation of the pages related to the transformers. My German is a bit lacking (think nonexistent) and machine translators don't seem to handle the navigation of the site... Perhaps they offer a comparable transformer (in terms of size, weight and electrical specs) with 117V primary ? Anyone speak enough German to figure it out from the site?

They only sell to companies...

up to ten primaries with taps...
up to 14 secondaries with taps...
at any voltages, any power,
generally without higher pricing for individual configuration...

[punkin]

I keep coming back to this thread. I'm in love with this build. Finding the perfect USA supplier for the power transformer is my hand up.

[armstrom]

You can build your own with two back-to-back transformers or use a 6 or 12V AC wall wart and a "backward" transformer.
I'm looking into the LO_PO transformer from weber that might do the trick. The spec sheet indicates a max heater current of 1A but a 12AX7 + ecc99 needs 1.1A (close, but over the spec). I have sent an email to the guys at weber to see if I can exceed the heater current rating by 10% and still be safe. Other than that, the HT current should be adequate.

[punkin]

Hi there...I'm back.

I contacted Antek and asked them for a substitute for the 269EX. They came back with this http://www.antekinc.com/details.php?p=46 . It's not an "exact" match but it's pretty darn close. Anyone see any potential problems with using this transformer? It's WAY cheaper and I like the idea of using a torroidal. The first and only thing I see is dropping voltage down a little bit to match the schematic voltages.

Anyone?

[FcKw]

Hi,
the 200V should be just fine, but it's got a 6,3V output like in the datasheet not a 3V output like it is described on the website, right?

Patrick

[punkin]

Thanks for taking a look at that for me Patrick,

It was a bit confusing for me too. The first page in the product spec shows 3Volts but then when you look at the PDF detail, it shows two secondaries with 6.3 at 3amperes each. The part that's got me a little cuatious is the cost...it's $30 USD which is significantly cheaper then the hammond and by the looks of things...a little smaller perhaps (lower profile certainly) and again, the appeal of a torroidal from the noise standpoint is really attractive.


Steph

[FcKw]

Yes, it's significantly cheaper, but it should be right, because over here in europe you can get similar torroridals for about 20€ wich is around 29$, too.

Patrick

[punkin]

Hello uncle Visa 

Thanks Patrick

[armstrom]

Everything I've read online seems to indicate these Antec transformers are very high quality. One nice thing about that 100VA rating is that it will support a MUCH larger amp than what we're talking about in this thread. The secondaries, when used together (either in parallel with a full-wave bridge rectifier or as a center-tapped setup) should supply 440mA at 200V. In comparison the 269EX is only rated at 65mA. Of course, Hammond rates its transformers in maximum DC current while the Antec is rated in AC current, but the gap between the two is still huge. You also have more than enough filament current to drive as many tubes as you could want   I wouldn't let the price put you off though. Keep in mind that hammond pretty much owns the market when it comes to traditional EI power transformers for tube amps. They charge what they do because they can. Antec makes all sorts of toroidal transformers and being a smaller manufacturer they can easily tool-up to make all sorts of variations. Not to over-simplify the design process for toroidal transformers, but my guess is that it was pretty easy for antec to simply adapt some of the existing designs they have to be suitable for tube amps.

I contacted Antek a month or so ago and asked if they did custom work and if so could the reproduce a transformer similar to the one found on that german site. They didn't really give a clear answer but did say they would be coming out with a 50VA version some time soon. That should help cut down on the size and weight while still suppling more than enough current to run most small to moderate tube amp projects.

I wonder if it's worth contacting that German reseller to see if they can order a batch of 120V primary transformers from the supplier. If we can get enough people together it may be worth the effort.  If we could get a small toroidal tranny like the one Patrick used in his build (but with North American friendly 117-120V primaries) how many people would be interested?

[punkin]

I think I'd be in for one or two but wonder if shipping would make it cost prohbitive again.

[armstrom]

It depends.. The cheapest option is usually to package all of them up in one box and ship it overseas. Then someone here can re-ship to individuals. These are pretty small/lightweight transformers. And if there's no rush it shouldn't be TOO expensive to ship surface mail. Depends really. I see that Antek has posted some higher voltage (325V) 50VA power transformers on ebay. I'll contact them later to see if they have the 100V x 2 50VA available yet. It should be about 3.5" diameter x 1.5" tall. Bigger than the one from the german company, but also MUCH higher current rating. You could build an AX84 P1 or a a low-voltage champ using a transformer like this without a problem.

-Matt