Not done yet

[AntLockyer]

I've been building this for a while.

Based on a schematic I found from the 50s that GEC published but I don't think ever made. It's a push pull design using KT88 valves that should make about 30 watts.

I added a choke input regulated power supply of my own design

Which should produce around 410v with 130mA of ripple for a 180mA draw (ie quiet enough).

I had the transformers custom wound for the application by a British firm and badly knocked together the chassis.

This is roughly how it looks now although everything other than the HT wiring is now complete.


I'll get on with finishing it at some stage and it's twin for Stereo operation.

[Bill Ladd]

Very tidy package!

Been a very long time since I've messed with amps and my experience is limited as is my knowledge of theory.

I was told and read many moons ago that cap inputs were better for higher output V and that chokes, while much better at regulating voltage, aren't able to provide as high an output as a capacitor.

Couldn't remember the formula that I had learned-- had to google it. (2*sqrt(2)/Pi)*Vrms)

What have you added/modified to get output that high?

[GrantM]

very cool. i'm a hi fi guy myself, but i've never really looked in to the tube thing.
how does one go about finding out more about them?

-g

[Cookietruck]

here are some bass reflex horn speakers i put together.
got plans, pretty much followed them.
~97db so they are pretty loud with my 6watt power amp.






edit: oh it was early morning post. i see the this is the "not done yet." thread. well, they're done for now. i do plan to upgrade drivers eventually...so not done...

[Bill Ladd]

Oh. I see it on your schematic. The increased gain provided by the the dual tapped (push pull) transformer?

Bear with me here. I can barely read/understand these things, but I think that's what I'm seeing.

[Too Tall]

place to merge related threads

[swt]

Cool amp.

very cool. i'm a hi fi guy myself, but i've never really looked in to the tube thing.
how does one go about finding out more about them?

-g

If you mean building them or understanding the physics, this has always been my favorite intro
Jones, Valve Amplifiers. It's really just basic analog electronics, for which, for me at least, the canonical reference will always be Art of Electronics. Be careful with the HT (High Tension == High Voltage), cause that can really F you up.

[AntLockyer]

Very tidy package!

Been a very long time since I've messed with amps and my experience is limited as is my knowledge of theory.

I was told and read many moons ago that cap inputs were better for higher output V and that chokes, while much better at regulating voltage, aren't able to provide as high an output as a capacitor.

Couldn't remember the formula that I had learned-- had to google it. (2*sqrt(2)/Pi)*Vrms)

What have you added/modified to get output that high?

Thanks, I use 550v output from the transformers which is much higher than I would have needed with a cap input. So it's more expensive from a manufacturing point of view and a bit more wasteful form a running cost point of view.

[AntLockyer]

Cool amp.



If you mean building them or understanding the physics, this has always been my favorite intro
Jones, Valve Amplifiers. It's really just basic analog electronics, for which, for me at least, the canonical reference will always be Art of Electronics. Be careful with the HT (High Tension == High Voltage), cause that can really F you up.

I agree with both of these recomendations.

[AntLockyer]

here are some bass reflex horn speakers i put together.
got plans, pretty much followed them.
~97db so they are pretty loud with my 6watt power amp.

nice what are the amps? 300b?

[Too Tall]

Speaking of...
http://www.davidberning.com/
Dave is a local and old pal., multiple PBP rider too.
Gave his car to charity when the gas evaporated ;)

[AntLockyer]

What, no way? I heard a ZOTL for the first time this year it was great. What a small world.

[Cookietruck]

nice what are the amps? 300b?

preamp on the right, power amp on the left (taboo).
preamp is SET using ecc88/6dj8 tubes.
the power amp uses a 12a*7 type driver tube and EL84 power tubes, it's SEP design. built by www.decware.com
really pretty neutral sounding, fast, clear, detailed and 3dimensional sounding.

[steve garro]

Ross Schafer of Salsa Cycles fame is into this kinda thing: http://six-ninedesign.com/gal/index.htm

[GravityAngel]

Another long time time audio bug. Simple setup, but oh so very musical. Oracle TT with Koetsu/Zeta cart/arm, Jolida CD deck, Jolida 801 amp, Altec A7s, 604s speakers. Currently have about 8oo LPs and 1500 CDs in my collection, split evenly between Jazz, Blues, Rock, and Classical.

[GravityAngel]

Speaking of...
http://www.davidberning.com/
Dave is a local and old pal., multiple PBP rider too.
Gave his car to charity when the gas evaporated ;)

I love his amps, someday...

[El Chaba]

I've been building this for a while.

Based on a schematic I found from the 50s that GEC published but I don't think ever made. It's a push pull design using KT88 valves that should make about 30 watts.

I added a choke input regulated power supply of my own design

Which should produce around 410v with 130mA of ripple for a 180mA draw (ie quiet enough).

I had the transformers custom wound for the application by a British firm and badly knocked together the chassis.

This is roughly how it looks now although everything other than the HT wiring is now complete.


I'll get on with finishing it at some stage and it's twin for Stereo operation.

What is it with you Brits and 30 watts?....I sold my Vox AC30 about 2 years ago...there is something about a tube amp...(or valves)

[rwsaunders]

I used to build a Dynaco amp, preamp and tuner every Summer when I was in college, and sell them in the Spring when I ran out of cash. The buyers were always about 20-30 years older than me and were true audio geeks. Those were the days.

[OnTheEllipse]

i love the Chihuahua peeking it's head in the corner. I thought it was photoshopped at first.

I spend at last a half hour every day right now researching a tube amp purchase for my klipsch speakers. Jealous!

[OnTheEllipse]

didn't notice the BPB album at first....

...wanna be friends?