• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Amp to Drive Lowther DX3's in Rear Loaded Horn

ranger3

Member
2007-03-02 8:29 pm
I generally hang out in the Class D forum, but I wanted some of your opinions.

I'm considering switching to a tube amp and trying to find out if it's worth it. I will try to be very specific on my configuration and goals.

I'm looking for an amp that will noticeably improve (that's subjective, I know) my current sound. I don't know how my system could sound better, so I can't define improve. I'm not saying it's the best, I just don't know what the weakness are. Except for the subwoofer which I'll replace at a later date.

I would like to stay under $500 if possible as this is my first dip in the tube pool.
I live in the USA. I am capable of light soldering jobs but prefer plug and play.

I have the following:

Computer playing Flac optical out to Minidigi/Minidsp. I used REW EQ and calibrated my system by applying the biquads to the Minidsp. The MiniDSP feeds a Trends Audio Hybrid Tube pre-amp. From the pre-amp, I send to a Virtue Audio class D amp and the subwoofer. The Virtue Audio sends to Lowther DX3s in Medallion rear loaded horns 100+ efficiency. High wattage not a requirement with these speakers.

I listen to 60s - today rock and roll mostly, some jazz, alternative rock.
Some favorites are Supertramp, Dave Matthews, 311, and love female vocalists.

Room is medium with carpet and couches. Vaulted ceiling. Room dimensions 18x18 feet. Speakers almost corner loaded.

I'm very happy with my current sound. Clarity, imaging, sound stage and dynamics are all very good, but once you have the bug, you always look for the next improvement.

Talk me into something or talk me out of something.

Thanks,

Allen...
 

tinitus

diyAudio Moderator R.I.P.
2005-11-24 1:47 am

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I'm sure those amps will drive the DX3s, but will there be a noticeable improvement in the sound?

Is the Pope Catholic? Tube mid-range is where it's at!

The budget is $500. A very well executed "El Cheapo" will pass financial muster. Build with "reissue" TungSol 6V6s and above average 12AT7s. Buy Dynaclone Z565 O/P trafos from Triode Electronics. A complete set of power "iron" can be sourced from Allied Electronics. Other than a chassis, for which a large commercial kitchen cake pan will do, tubes, passive components, etc. come from Jim McShane.

The Z565 is a price/performance champion. You have to spend MORE to get better performance. As you have a decent preamp, you don't need the volume control. The RC high pass filter at the circuitry's I/P changes to 0.068 μF./150 KOhms. Above average O/P trafos provide freedom from core saturation worry. :) So, blocking the worst infrasonic noise is sufficient. F3 of 0.068 μF./150 KOhms is a "perfect" 15.6 Hz. :D

BTW, should you so choose, you could build with triode/UL mode switches. Triode wired "finals", as shown in the schematic, are good for approx. 6 WPC. That's PLENTY for your horns. However, being able to switch to UL mode gets you about 12 WPC and other speakers can be tried, with success.
 

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ranger3

Member
2007-03-02 8:29 pm
Is the Pope Catholic? Tube mid-range is where it's at!

The budget is $500. A very well executed "El Cheapo" will pass financial muster. Build with "reissue" TungSol 6V6s and above average 12AT7s. Buy Dynaclone Z565 O/P trafos from Triode Electronics. A complete set of power "iron" can be sourced from Allied Electronics. Other than a chassis, for which a large commercial kitchen cake pan will do, tubes, passive components, etc. come from Jim McShane.

The Z565 is a price/performance champion. You have to spend MORE to get better performance. As you have a decent preamp, you don't need the volume control. The RC high pass filter at the circuitry's I/P changes to 0.068 μF./150 KOhms. Above average O/P trafos provide freedom from core saturation worry. :) So, blocking the worst infrasonic noise is sufficient. F3 of 0.068 μF./150 KOhms is a "perfect" 15.6 Hz. :D

BTW, should you so choose, you could build with triode/UL mode switches. Triode wired "finals", as shown in the schematic, are good for approx. 6 WPC. That's PLENTY for your horns. However, being able to switch to UL mode gets you about 12 WPC and other speakers can be tried, with success.

This looks good, but it's beyond my pay grade. I flip bits for a living (Network Engineer). I've got an electronics repair shop around here that could probably do it if I provide the parts. Is it worth it or should I try to buy one used?
 
"El Cheapo" is a DIY project. Those of us who worked on it placed it in the public domain. The people who built the project are highly unlikely to part with fruits of their labor, as it sounds too [email protected] good. :D You will have to factor your tech's labor into the overall cost. $500 buys the top notch parts, but I doubt you'll have much left for labor. Edcor offers decent O/P trafos at lower cost than the Z565s, but ...

BTW, I too "shovel" bits and bytes for a living. I'm a CICS System Programmer.
 

ranger3

Member
2007-03-02 8:29 pm
"El Cheapo" is a DIY project. Those of us who worked on it placed it in the public domain. The people who built the project are highly unlikely to part with fruits of their labor, as it sounds too [email protected] good. :D You will have to factor your tech's labor into the overall cost. $500 buys the top notch parts, but I doubt you'll have much left for labor. Edcor offers decent O/P trafos at lower cost than the Z565s, but ...

BTW, I too "shovel" bits and bytes for a living. I'm a CICS System Programmer.

I could spring for the labor. I'm starting to really like this idea. The repair shop is owned by a couple of old timers. Really nice guys.

Plus it's still DIY, even if I'm not manning the soldering iron. Right?

What do I mount it on?

Thanks for getting me started in the right direction. I know there is no going back after this. Just like when I got my Lowthers.

There's a saying. Lowthers for life. Is there also a saying, tubes for life?
 

lousymusician

Member
Paid Member
2005-11-24 4:10 am
NorCal
An aluminum plate in a wood frame is a common choice. A large, heavy gauge aluminum, commercial kitchen cake pan is another cost effective option. Check this out.

I built my Tubelab Simple SE into an aluminum roasting pan. It made for a nice, sturdy, cheap chassis.

The SSE might be another choice. I think mine came in around $500, using Transcendar OPT's, an Allied power trafo, and EL34's. It's a simple build on a single circuit board. Sounds nice with full rangers, though I've never had the chance to hook it up to a Lowther.

Bill
 

ranger3

Member
2007-03-02 8:29 pm
Well I took the plunge. I ordered the Stereomour from Bottlehead. People seem to like them. Since this is my first build, I need it to be easy. If it's becomes to difficult, I know someone who could help.

After I ordered from Bottlehead, I realized they take a long time to ship. Has anybody had any experience with Bottlehead?
 
Bottlehead experience

First of all, Dan makes tremendous bang-for-the-buck amplifiers. You will enjoy these. In fact, you can upgrade tubes and output transformers later if you like the overall sound in order to get a little refinement.

Expect to take 15 hours on the build, give or take depending upon your experience. The instructions are on a CD, and they are excellent.

Finally, they work great with Lowthers. Dan has a pair of my Alerions in house.