Author Topic: alexg's DIY Tube Projects (Read 59900 times)

edrel sison · « **Reply #60 on:** May 16, 2007 at 10:35 AM »

3B28 half wave rectifier. i have two of these so that i can make a FW outboard PSU for big amps.

romymartinez · « **Reply #61 on:** May 20, 2007 at 01:33 PM »

Nice sweet work of art, alexg. Congrat!

alexg · « **Reply #62 on:** May 20, 2007 at 08:01 PM »

Just finished gluing and sanding the narra parquet strips on my inverted BIB with karlson slot (from diyaudio.com, a folded horn). This speaker uses the 4.5" Fostex 127e fullrange driver.

You would not believe the bass am getting from this 4.5" driver, bass is a bit better than my Evo 10, and the vocals and highs are to die for. Here is a picture of the un-varnished cabinet:

On the right on my audio rack, my diy KT88/EL34 SE amp, my 7193 "horny" preamp, the preamp PSU below, not shown is my Monica2 DAC (from diyparadise.com) and my 6688 line stage for the DAC. Also not shown is my very old Philips DVD player that I use to play CD and my 250GB MediaGate audio and movie player.

The folded horn speakers will be stained cherry and finished either with Tung Oil or Polyurethane satin finish.

cybermms · « **Reply #63 on:** May 20, 2007 at 09:37 PM »

Congrats, Alexg! Set up shown is best for "show". I don't see the Pi-10. Have you tested it.

I have invited Edrel to organize the DIY group for the July 6, 7 and 8 in Alabang.

cyber

alexg · « **Reply #64 on:** May 21, 2007 at 07:40 AM »

Quote from: cybermms on May 20, 2007 at 09:37 PM

Congrats, Alexg! Set up shown is best for "show". I don't see the Pi-10. Have you tested it.

I have invited Edrel to organize the DIY group for the July 6, 7 and 8 in Alabang.

cyber

The Pi-10 is for HT and for my SS amp.

It sounds great, thanks.

dana · « **Reply #65 on:** May 21, 2007 at 07:52 AM »

Very nice work, Alexg!
Mukhang wala munang upgrade for the longest time...

Halos complete DIY set-up na yan...

alexg · « **Reply #66 on:** Jul 04, 2007 at 10:59 PM »

I started breadboarding my 832A PP monoblocks.

I started with 6n1p as drivers using only one triode and now am using a paralleled 12au7.

The phase inverter is a transformer (not an interstage). If I was doing a stereo, then it would be possible to do a 3 tube push pull amp.

With the transformer phase inverter, the sound is very, very good! I just needed to deal with the hum (might be due to having an MDF board for a chassis). This amp has very, very good potential, it sounds better than my SE KT88!

Here are the pictures of the breadboarded amp:

The PSU is SS rectified and is CLCRC filtered, using electrolytic caps... (in contrast with my KT88 that I used motor run caps). The driver is plate choke loaded and currently biased using red LEDs which I plan to replace with an LM317 bias and later on a CCS based on the diyaudio CCS. The 832A will be biased using LM317s.

dana · « **Reply #67 on:** Jul 05, 2007 at 06:35 AM »

WOW

...Horny all the way

Am sure, it will turn out good just like the previous ones you just made.
Next update please

....

alexg · « **Reply #68 on:** Jul 05, 2007 at 09:10 AM »

Quote from: dana on Jul 05, 2007 at 06:35 AM

WOW ...Horny all the way
Am sure, it will turn out good just like the previous ones you just made.
Next update please ....

OT: Dana, are you going to the Alabang Audio Show?

ATJr. · « **Reply #69 on:** Jul 06, 2007 at 03:27 AM »

Quote

With the transformer phase inverter, the sound is very, very good! I just needed to deal with the hum (might be due to having an MDF board for a chassis). This amp has very, very good potential, it sounds better than my SE KT88!

hum should all but dissappear once you finalize lay-out on chassis...congrats, we proved the skeptics wrong! ......we can do it!!!!

tube amps are really about irons....and solid state biasing a bonus...

alexg · « **Reply #70 on:** Jul 06, 2007 at 07:53 AM »

Quote from: TonyT on Jul 06, 2007 at 03:27 AM

hum should all but dissappear once you finalize lay-out on chassis...congrats, we proved the skeptics wrong! ......we can do it!!!!

tube amps are really about irons....and solid state biasing a bonus...

I was reading the thread on the Seth Amp on diyaudio, and a lot of forum members were convinced that it will not work (frequency response problems, etc, etc), though the circuit designer was saying that it sounds very, very good.

Yes, Tony, we have proved the skeptics wrong! It can be done, and it does not need to cost an arm and a leg, (maybe it would cost just a couple of fingers though

).

Thanks for the winding design!

dana · « **Reply #71 on:** Jul 06, 2007 at 05:56 PM »

Quote from: alexg on Jul 05, 2007 at 09:10 AM

OT: Dana, are you going to the Alabang Audio Show?

still not sure...having beta sample run on new projects, with visitors

.
will try hard to be there...see/listen to our toy too and get d horny feeling...

832s.....hmmmmmmmmmmmmmm

alexg · « **Reply #72 on:** Jul 07, 2007 at 02:07 PM »

Assembled one monoblock on the unfinished aluminum chassis just to dry fit and position all the holes that needed to be drilled:

Now I am playing the system in stereo, excellent sound, excellent soundstage, minor hum issue (need further tweaking), bass is a bit flabby and the highs a bit too edgy, adjustments should fix this.

This amp have a lot of potential!

alexg · « **Reply #73 on:** Jul 11, 2007 at 08:08 AM »

Quote from: TonyT on Jul 06, 2007 at 03:27 AM

hum should all but dissappear once you finalize lay-out on chassis...congrats, we proved the skeptics wrong! ......we can do it!!!!

tube amps are really about irons....and solid state biasing a bonus...

Tony,

I took out the center tapped choke phase inverter and used a technique I read at Yeo's website (diyparadise.com) on his Simple EL84 PP amp. (driver tube plate to grid of one power tube, the grid of the other power tube to ground).

Promising too, more natural sound, a bit attenuated overall, but good. But of course, I really love the heft and weight of irons on a tube amp.

BTW, hum is still present on my prototype on the final chassis, I will try using shielded cables for signal cable, if I can't get rid of the hum, then I will rectify heater supply.

Regards,

Alex

alexg · « **Reply #74 on:** Jul 11, 2007 at 08:17 AM »

Latest picture of my 832 monoblocks:

The one on the right is the latest, the other one with the 6j5 mounted horizontally has the chassis drilled for a 9 pin driver that I was using before (6n1p and 12au7). I have to used a short piece of aluminum angle bar to mount the octal based 6j5.

alexg · « **Reply #75 on:** Jul 28, 2007 at 11:27 AM »

My new project, a pair of 832A monoblock amp. Here are the pictures:

Breadboarded.

I started using a 6n1p as driver, sounds good but too much gain. Tried 12au7, same thing, bass is more prominent. Finally settled with 6j5 for driver.

I used a transformer for phase inverter, sounds good and better than an LTP. Edrel Sison wound all the irons, and as usual, they sound great. But now, I settled with a self-inverting topology.

Here is the upskirt shot of the first prototype.

With the 12au7 driver:

Finally, with the 6j5 drivers.

The monoblock on the left still have the driver tube mounted on an alum angle bar (this allows me to experiment with different size driver tube sockets (nine pin and octal). The one on the right will be the final chassis with the 6j5 driver.

I just needed to sand and paint the chassis and it's done, except for some minor tweaks.

The sound: It sounds better than my SE KT88 that was at the last Alabang Show (the one paired with the Vandersteen 1C).

zHangGoku · « **Reply #76 on:** Aug 05, 2007 at 06:24 PM »

sir alexg, pwedeng humingi ng circuit diagram ng pre and power tube amp?

ATJr. · « **Reply #77 on:** Aug 06, 2007 at 01:37 PM »

Quote from: zHangGoku on Aug 05, 2007 at 06:24 PM

sir alexg, pwedeng humingi ng circuit diagram ng pre and power tube amp?

pm me your email and i will send you the schematics..

alexg · « **Reply #78 on:** Aug 06, 2007 at 08:29 PM »

Quote from: zHangGoku on Aug 05, 2007 at 06:24 PM

sir alexg, pwedeng humingi ng circuit diagram ng pre and power tube amp?

Tony can email you the schematic nung preamp, he is instrumental in the design of this preamp.

Which power amp do you need the schematic, the KT88 or the 832A?

Hear_me_shout · « **Reply #79 on:** Aug 06, 2007 at 08:42 PM »

Quote from: alexg on Aug 06, 2007 at 08:29 PM

Tony can email you the schematic nung preamp, he is instrumental in the design of this preamp.

Which power amp do you need the schematic, the KT88 or the 832A?

S' Alex/ Tony,

If you don't mind, pasend din sa email nang schematics. WOW na WOW ako last audio fair sa DIY room niyo. Will send you PM, thanks!

ATJr. · « **Reply #80 on:** Aug 06, 2007 at 09:37 PM »

for a first time diy, this should be okey, not complicated ang circuit, simple lang...tubes are available from Gerry, and chokes are available from edrel...

those who wish to build these horny amps, just fire me pm with your email....

zHangGoku · « **Reply #81 on:** Aug 06, 2007 at 10:52 PM »

Quote from: TonyT on Aug 06, 2007 at 01:37 PM

pm me your email and i will send you the schematics..

sir TonyT, thanky you very much.

Quote from: alexg on Aug 06, 2007 at 08:29 PM

Tony can email you the schematic nung preamp, he is instrumental in the design of this preamp.

Which power amp do you need the schematic, the KT88 or the 832A?

sir alexg, alin po sa dalawa ang maganda ang tunog? okay lang ba kung parehas ko hingin?

ATJr. · « **Reply #82 on:** Aug 07, 2007 at 07:44 AM »

you can start here:http://www.diyaudio.com/forums/showthread.php?s=&threadid=102510

832, 829, 815 are dual pentodes, they are not hard to drive judging from datasheets, one caveat though is low screen voltage rating, but this is not much of an issue imho.

alexg · « **Reply #83 on:** Aug 07, 2007 at 08:16 AM »

Quote from: zHangGoku on Aug 06, 2007 at 10:52 PM

sir TonyT, thanky you very much.

sir alexg, alin po sa dalawa ang maganda ang tunog? okay lang ba kung parehas ko hingin?

Go with the 832A, study this circuit: http://audiohobbyist.com/projects/832.htm

When you are ready to do your amp, PM me and I will tell you how I modified and tweaked the amp. My apology, I have not drawn the diagram of my 832A amp yet.

zHangGoku · « **Reply #84 on:** Aug 11, 2007 at 08:32 PM »

maraming salamat po mga sir.

alexg · « **Reply #85 on:** Sep 06, 2007 at 03:39 PM »

Quote from: alexg on Apr 06, 2007 at 12:53 PM

I was short of 1 pair RCA when I decided to put a simple toggle input selector switch.

The plate choke will be chromed.

This preamp have been done with several tubes now, on the original version, I used 7193 (half of 6sn7), then later, I used 6j5 (another version of a half of 6sn7), currently it has 12b4 tubes on it.

picture of the preamp with GE 12b4:

Tonight, am wiring it with 12au7 on a cathode follower, similar to the Foreplay III.

reynold · « **Reply #86 on:** Sep 06, 2007 at 04:23 PM »

Quote from: TonyT on Aug 06, 2007 at 01:37 PM

pm me your email and i will send you the schematics..

hi sir TonyT, interested din ako sa schematic diagram, gusto ko subukan maggawa ng sarili ko tube amp, hope you can give kahit yung pinaka-simple lang na diagram, first time ko lang po ito gawin, kaya pwede ring may instrauctions ng pag-gawa, parang for dummies ang dating, hehehe

btw, here's my email address.... [email protected]

TIA

alexg · « **Reply #87 on:** Sep 21, 2007 at 08:15 AM »

Finally, I had some spare time and started building my cathode follower 12ua7 preamp (Foreplay 3 inspired).

Trial layout of the components. No cheap surplus PC PSU capacitors were used, Nichicon electrolytics and ASC polypropylene in oil (also known as motor run) were used. Unlike the stock Foreplay 3, I used chokes on the PSU which sounds better than an RC filter for this linestage.

Assembly finished, tweaking still going on. The nice coke bottle tube behind the 12au7 is an 0D3 voltage regulator. Tweaks include CCS plate load and CCS cathode bias, well filtered SS rectified PSU using mostly polypropylene capacitors. Sound is quite excellent.

Preamp at night!

s2kov · « **Reply #88 on:** Sep 21, 2007 at 04:49 PM »

naks! tapos na pala!

congrats!

alexg · « **Reply #89 on:** Sep 24, 2007 at 09:51 AM »

Quote from: s2kov on Sep 21, 2007 at 04:49 PM

naks! tapos na pala!

congrats!

Thanks Andy. This preamp really sounds good with my SE KT88 and my 832A PP amp.