OT: Show us your DIY tube amps

[zelgall]

Hello,

You certainly don't need a "big" tube to have a non-whimpy amp. What is needed is a proper power supply, and a small tube can easily rock on a Altec system. In the end, we all listen to a modulated power supply. How good is that power supply?

Most audio power supplies are very-much inadequate, so people compensate for that by using bigger tubes, to make up for their poorly designed, poorly wired, poorly power supplied tube amps. However, if you do it right, it can be done with a single 2A3 or maybe even a single 6AQ5, triode connected. Little tubes can and do often sound better than bigger tubes, and the DHT Type 71A and Type 45 come to my mind.

Little tubes, well implemented, are NOT whimpy at all and can have fantastic bass, PRAT, etc. I have such a DIY amp sitting in my living room powering EV12-TRXBs right now, 1.4 Watts output with a 18 pound purpose-designed power transformer. Wimpy power supplies are whimpy. Poor executions are whimpy. And all such amps are musically uninvolving to hear.

LowOhms

Jeff, I'm also a user of low powered amps but regardless of how perfect the power supply is, the power and therefore the volume that the amps will play at is restricted. Even with high eff speakers you can't reach party approved levels with a couple of watts. I use either model 19s or 604-8Gs in 620 style cabs so the efficiency is there. If you have dynamic music with realistic peaks, you're going to be limited by the low power of 2A3 amps. Don't get me wrong, I use them but I also have other amps for big music and party days.

[LowOhms]

Attachment 2061

Since this is the "show me" thread....would you be willing to post a picture and schematic of your amp?

Sure, give me a little time to snap a photo or two. Amp is 95% done. My typical power supply to Finals is shown in step-test simulation, attached. As you can see, it settles in 22 mS, and has less than 10 Ohms DCR spread over L1 and L2.

LowOhms

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Jeff, I'm also a user of low powered amps but regardless of how perfect the power supply is, the power and therefore the volume that the amps will play at is restricted. Even with high eff speakers you can't reach party approved levels with a couple of watts. I use either model 19s or 604-8Gs in 620 style cabs so the efficiency is there. If you have dynamic music with realistic peaks, you're going to be limited by the low power of 2A3 amps. Don't get me wrong, I use them but I also have other amps for big music and party days.

Zelgal,

No doubt about your report. I fully believe you. But you are guessing about "how perfect" sounds, because I believe you have never heard it. You most likely have a "typical" 2A3 or low powered amp, and yours won't play at all as I describe. Its correct, its not just one thing, the power supply, that matters, everything matters, and I have pointed out the three biggies, lay out, wiring, and supply.

For the last 5 years, I have heard properly power supplied, wired, executed SE 2A3 amps on GPA 604s, and they do just the opposite of what your amps sound like! They don't leave me wanting for more. I HAVE DEMOED THE SYSTEM at RMAF, AND HEARD THEM IN MORE THAN ONE VENUE.

LowOhms

[Old Guy]

But you are guessing about "how perfect" sounds, because I believe you have never heard it.

Neither have you. Please cut the bull and stick to reality. No human has perfect ears. You may have heard what compensated for your ears adequately.

[mah]

How do ageing audiophiles maintain their powers of aural discrimination as their hearing degrades with age? There are hi-end audio reviewers who are no Spring-chickens.

[Alien_Shore]

Edison used to chomp his teeth down on his player to transmit the vibrations through his teeth and jaw into his skull.

[Phil-G]

porn mags start coming with braille pictures

[gortnipper]

Despite the url, this is not xxx-rated

Girls with Vinyl Records

[zelgall]

Attachment 2061


Sure, give me a little time to snap a photo or two. Amp is 95% done. My typical power supply to Finals is shown in step-test simulation, attached. As you can see, it settles in 22 mS, and has less than 10 Ohms DCR spread over L1 and L2.

LowOhms

- - - Updated - - -




Zelgal,

No doubt about your report. I fully believe you. But you are guessing about "how perfect" sounds, because I believe you have never heard it. You most likely have a "typical" 2A3 or low powered amp, and yours won't play at all as I describe. Its correct, its not just one thing, the power supply, that matters, everything matters, and I have pointed out the tree biggies, lay out, wiring, and supply.

For the last 5 years, I have heard properly power supplied, wired, executed SE 2A3 amps on GPA 604s, and they do just the opposite of what your amps sound like! They don't leave me wanting for more. I HAVE DEMOED THE SYSTEM at RMAF, AND HEARD THEM IN MORE THAN ONE VENUE.

LowOhms

Hi Jeff. Two L's. It's not my name but I've used it here for years.
Regardless of how many amps you've heard, there are others that are better.
I was making amps when I first saw you in Sound Practices. I know you've had a lot of experience with building and listening to top rate systems but that doesn't mean I've been sitting on my ass for 20 years. I've also been refining my system and learning about tube amp design.
I appreciate that you have strong opinions about your friend's products and methods but there's more than one way to sonic bliss. I'd say that I've surpassed the mainstream sound by a fair margin as I'm sure you have. I couldn't say that my amps sound better than others but nor can anyone else. If you haven't heard it personally, you don't know what it sounds like.
Different directions with the same destination.
Kyle.

[LowOhms]

Hi Jeff. Two L's. It's not my name but I've used it here for years.
Regardless of how many amps you've heard, there are others that are better.
I was making amps when I first saw you in Sound Practices. I know you've had a lot of experience with building and listening to top rate systems but that doesn't mean I've been sitting on my ass for 20 years. I've also been refining my system and learning about tube amp design.
I appreciate that you have strong opinions about your friend's products and methods but there's more than one way to sonic bliss. I'd say that I've surpassed the mainstream sound by a fair margin as I'm sure you have. I couldn't say that my amps sound better than others but nor can anyone else. If you haven't heard it personally, you don't know what it sounds like.
Different directions with the same destination.
Kyle.

Hello Zelgall,

Yes, I noticed the single L but I didn't have the time earlier to do an edit. Sorry. Two Ls can also mean L1/C1/L2/C2, my favorite filter design to the Finals.

When you post that your SE 2A3 amp can not play your Altec speakers satisfactorily to "party or boggie" I immediately obtain a pretty strong hint as to what you are building. That is why I counter-posted to you Zelgall in the first place.

What I want from a low powered SE tube amp is ALL-OUT PERFORMANCE, the best possible result that can be had, within reason of my budget.

You say " Different directions with the same destination."

Respectfully Zelgall, I don't believe that you and I presently share same destination .....

Your destination, from what I read that you posted, is "an acceptable result and well above average playback."

My destination is to have the best possible result, all-out audio performance.

These are not the same destinations, are they?

I fully believe there is only ONE optimal way to get the best result.

Additionally, I think I have found out what that is, what I now a days call a "modern" power supply. This came about as a result of 30 years of myself and another individual experimenting with tube amp power supplies.

Zelgall, have you ever read the chronological postings I complied from the AA Forum by Messers John Swenson and John L. Hasquin, two graduate E.E.s?? It is their direct DIY build and listening experiences with "modern" supplies. Both these guys are very well respected in audio.

If I never sent it to you, you should read it, and you would understand better what I am trying to communicate.

One would NEVER say "different directions to the same destinations" after reading their own posts.

I would be very happy to send them to you, ( or any Altec Forum Member to review at your convenience ), as it outlines the basics of what I call a "modern" power supply. My email address is drlowmu AT gee male.com.

I like what Winston Churchill once said " I am very easy to please, I am always satisfied with the best there is" ... That is fully what I want in 2013 for a low powered audio amp to power Altec type speakers Zelgall.

I don't hedge, I tell you straight-out my goal and objective. I can back it up too.

Alien_Shore, photos tomorrow.

LowOhms

[LowOhms]

Hi Alien_Shore,

Here is my own "unique" 2013 DIY design / work in progress, a 49 pound stereo DC coupled two stage amp.

Very direct, dynamic and transparent sounding.

Its a half of a triode 12AY7 low noise microphone driver tube, directly coupled to a 6AQ5 / 6005. This is a ("dynamite" because of tiny-spacing) pentode tube, that is triode connected. Output transformers are delicious Magnequest DS-050s. Zero Negative feedback.

Power output is 1.4 Watts but this amp has about a 400 Watt power supply supporting it, and is uniquely wired, with multiple paralleled spans of Kimber Kable TCSS, each amount determined by ear, for maximum bandwidth and transfer efficiency - hence dynamic contrast ability, which I believe is a first in audio.

Rectification is by dual directly heated 5V3As, and the custom designed ( by me ) power transformer sports an uber-low DCR of only 8 Ohms, ( end to center tap ) on the secondary. My power supply's winding wire can do 900 mA. but the entire amp idles at 60 mA. or less. L1 choke is only .8 Ohms DCR and L2 choke is only 6 Ohms DCR...... compare that DCR with anything else you have ever seen on a tube amp schematic !! This power supply delivers energy in the time of the music. The Finals supply is VERY fast settling, under 50 mS. ( See earlier PSUD simulations as my example .)


The front end B+ has under 2 mVAC of ripple, and it operates with a KISS one-part shunt regulator with no feedback. There is a final L/C filter to the front end, sub 1 Ohm DCR for the L, with high quality DynamiCaps feeding the driver tube's anode resistor, with less than 1/4 of an inch of lead length between them.


Chassis is Golden Ratio proportioned, made of 14 gauge, with welded corners, powder coated Midnight Blue Wrinkle with a little pearl in it, crummy photos don't capture it. All tubes are Golden Ratio conservatively run, and will last tens of thousands of hours and will consistently perform.

Notice in the third photo, my use of multiple TCSS wiring on cathode cap ground returns, and the use of a SHORT central "star" ground. The amount of paralleled wire for every span was selected by ear.

In the last photo, you will see another first in tube audio, the lead outs of the Magnequest DS-050 output transformers have been modified to multiple TCSS for each span, determined by ear. This provides maximum signal transfer of a linear kind, and a dynamic contrasting capability, that is a WHOLE lot of fun to listen through critically.

Two stages, direct coupled, well wired, with a great supply ..... this amp is easily as good as I have executed in 60 years of me hearing Altec 604s. Proof of the pudding is in the eating.

My Dad, by the way, installed a new 604B in our family's rec room in New Jersey .... when I was only 8 years old.

This is my not-quite finished prototype, if I built another one, it would be neater !

LowOhms