SE OT

[3rdof3]

I'm looking for a SE OT that can handle 2 EL34/6L6GC in parallel. All the Hammonds I've seen look to be just under the rating needed.

Basically just trying to get more headroom/louder for a high gain guitar amp I've designed.

Thanks in advance!!

Will
DYNA-LEAD Amplifiers

[FYL]

Dobermann sells a big chuck of iron manufactured by Heyboer. Up to 180 mA pri current; 2.5K, 4K and 6K pri.

http://shop.dobermanamps.com/product-p/xfrm-dob20wse.htm

Triode has a Magnetic Components-sourced el gordo OT with a 1K25 pri and 225 mA max current. You can obtain a higher pri by playing with secondaries.

http://store.triodestore.com/30wseot.html

One Electron offers three models - available from AES and other distribs. Their 1K6 UBT-1 is rated at 160 mA.

http://www.one-electron.com/trans.html

But the real question is: why bother with PSE for only a meager and nearly imperceptible 3 dB gain in power?

[3rdof3]

I prefer the SE sound to the PP. I don't *need* the extra volume, but would like to offer it should someone need more volume.

I have that Doberman OT in my amp now. I didn't realize it could handle the extra tube. EXCELSIOR!

Off to tweak and install a bigger PT ...

Thanks!

[PRR]

The Doberman is correctly proportioned for 20W out, 50W dissipation, 0.145A and 360V for 2.5K or 447V and 112mA at 4K or 550V and 91mA at 6K.

The 30WSEOT is correctly proportioned for 30W out, 75W dissipation, 0.225A and 333V for 1.25K. This is beyond safe for two 6L6GC or EL34, use three (or a six-pack of sweet 6V6, a sex-Champ). It might be re-specced for a higher voltage/impedance, they say you can, and at that price you sure should be able to, but they don't give hard numbers. At this high power, a 5F6a Bassman power transformer may be marginal for B+ load (the Bassman did not run ~~220mA ALL night long, and the heater may be shy an Amp). This is probably the upper limit of what a traveling musician can carry.

Hammond 125ESE can reasonably be run at 5K 450V 90mA, 41W dissipation 16W output. While this is over its rating, it sure won't overheat, and the slight bass-slump is not a problem for guitar.

Doberman: 20W $64 = $3.20/Watt -- shipped to Maine, $73.44, $3.67/W
125ESE: 16W $45 = $2.81/watt -- shipped to Maine, $58.44, $3.65/W

Scale your raw B+ 10%-20% higher to allow for cathode-bias, B+ filtering, and general losses.

[bigdaddy]

Doberman is not the most reliable company. It's the guy from AX84, I did have a run in with him over his business practices. He takes your money fast without having the parts in stock so you wonder were you're transformer is. I emailed him and finally he admitted he's waiting for some to be made. Well why not just say so, he just took my money and let me hang. I will never order anything from him again. I don't do business with vendors who are not up front and honest. He does not upgrade his web site and you have no idea if he has anything in stock and he takes a few weeks to let you know.

I wish Doug carried more parts.......

His OT's are made by hey-bore, they sound OK, I have in fact 2 amps built exactly the same sitting waiting for me, one with the Doberman and one with the 20 watt and expensive Hammond, both with a KT88. I am curious how they sound, but my spinal condition has been acting up and I have not had the ability to work on them. These little amps turned out to be very heavy...LOL....I made both out of Blackheart heads. I'm sure both could easily run 2X 6L6GC/EL34.

[phsyconoodler]

Quote:"All the Hammonds I've seen look to be just under the rating needed."

I have built a few SE amps with KT66's and 6L6's in parallel and I use a Hammond 125FSE.No problems and they sound fantastic.
 
 Check my website under "custom builds". The amp actually has lots of headroom,but the clips are with the amp cranked with a Les Paul.

[bigdaddy]

In my working with SE amps I have found that they really sound good when you have a pentode driving them. Much better then a triode. So my fender type SE amps use a 12AX7 but some of the higher gain models use a triode into a pentode, like half a 12AY7 or a 6AV6.

The use of the Pentode brings the amp to a whole other level, I have had success with the 5879, EF86 and 6SJ7. So if you are running a pair of 6L6s you might want to consider using a pentode which makes up a lot for the loss from a tone stack.