Pictures of your Tubelab amp

[Alan Hope]

Originally Posted by cotdt

those are big 45's. how do they sound?

Out the box ... muddy. After 8 hours or so - to my great relief - they opened up, and are now better (marginally but noticably) in every department than the Sylvanias they replaced.

Bottom end is extended and weighty, top now very good indeed ... though I am glad I have supertweeters, because they might not have quite the sparkle to work well with full-rangers.

It is so hard to judge an individual component of a system. BTW they look fantastic!

[cotdt]

Thanks Alan! I will give them a try!

[acceler8]

I finally finished my TubeLab SE build (almost a year and half total). Well, mostly finished. I have a blank-off plate where a B- voltage meter will go (I'm thoroughly dissatisfied with the availability of panel meters.) I also have stalled on trying to get a microcontroller setup for voltage/temperature monitoring. Since these items do not affect the function of the amp, I decided to call it done and quit chasing rabbits. Here are some specs:

Hammond Chassis (17"x10"x3") 1441-32
Edcor XPWR131 Power Transformer
100uF 370 volt AC Motor Run Capacitor
Transcendar 10H 100Ohm Choke
Transcendar TT-020-OT 20 Watt OPT (3K to 4, 8, & 16 ohms, 18 Hz to 100 kHz)
Used Raytheon 5842
Guigang 300b (very cheap from eBay)
Sovtek 5AR4
Inverted build (tube sockets on top/components on bottom)
Remote 4-pin sockets for 300b
Fan cooled

By mounting the transformers along the edges of the chassis, I was able to avoid needing reinforcements. The total weight is 34 pounds, and there is no noticeable flexing. I chose this size because the lengthwise dimension (17") is close to standard stereo equipment (plus it gives plenty of room to work). I am using vintage GE panel meters to indicate the bias of the 300b tubes. I used the cheapest nastiest Hong Kong 300b's I could find (I think they were $103 shipped for the pair). I wanted something inexpensive in case I had made any mistakes in construction. My plan, now that the testing phase is complete, is to get better 300b tubes and keep the Guigang tubes as spares. The Transcendar choke is not pretty, so it is mounted to the inside of the chassis (front left - in front of the Edcor power transformer). B+ is 408V, Bias is at 68ma, heat sink with fan on is between 89f and 92f (76f ambient). With the fan off, the amp only runs for about 8 minutes before the regulator shuts down. I'm not 100% pleased with the fan, and it is audible. I have two other fans to try (lower db but also lower static pressure ratings). If I can lower the fan noise, and keep the heat sink under perhaps 110f I'll be happy. The fan is a blower type, and is mounted to the bottom panel. It blows directly on the regulator heat sink, and exits through a hole in the opposite side of the chassis. I'm guessing that the caps and such get some small benefit from the moving air currents (hopefully enough to extend their life). For the power LED, I tapped off the 5VAC heater feed from the transformer. I used a diode in line with a resistor and a small 100uf cap. DC voltage was a little over 7.1V and I used a 560 ohm resistor between that and a green LED.

Connected equipment:
Pioneer PL-540 Turntable
Audio-Technica AT440MLa Cartridge
Hagerman Technology Cornet 2 Phono Stage (built from PCB)
Adcom GTP-500 Pre-Amp
Tri-Trix TL Speakers (89db -boo)
Tivoli Audio subwoofer

My first impressions with this amp once connected to my main speakers were surprising. I've never had the chance to listen to a Single Ended amplifier (or even a DHT for that matter). So it was a leap of faith to build this amp, and I was very concerned about volume levels and bass availability. I knew that my speakers were a poor match (although they do have a fairly flat impedance curve). I had already decided that my next project would be some full range horn speakers just for the TSE. On the first song, I was BLOWN AWAY! Not only was the volume very respectable, the bass was amazing! In fact, there was almost too much bass. Just to be sure, I disconnected my subwoofer. It's no longer needed now. However, there was a problem. My first record was Silversun Pickups / Pikul EP. I kept hearing things that shouldn't be there. At one point, there was some fuzziness where it shouldn't be and at another point the sounds seemed to fade left to right and back. Some instruments sounded harsh, and others sounded thin/reedy. I was deeply worried. I then tried another record (Pink Floyd / Wish You Were Here -reissue). I don't like using words like creamy, sublime, or golden honey to describe music/sounds. But it was. I could close my eyes, and I was in another place. I no longer have any doubts that this was the right amplifier to build. I've since played about 6 or 7 records through the TSE, and overall it sounded amazing. I'm still in shock at both the volume and bass levels. For comparison, my previous amp was a Mark Hill MC-6L6GC (just like a Yaqin MC-5881A) which is a 6L6 push pull tube amp; and a Peter Daniels Chip Amp before that. Connected through the same equipment/speakers the TSE has dominantly better bass than both other amps! I did notice that on fast technical sections of music, the amp did seemed to get tripped up. Thankfully, this only happened once or twice and occurred while playing music that was way too aggressive. There is no hum whatsoever, although I'm sure that my insensitive speakers help here.
I have heard many tales of good audio gear revealing flaws in certain recordings. I have always thought that was rubbish. How can better equipment make something sound worse? But now I know. I'm not sure how I feel about that. On one hand, I like what this amp does to good recordings. On the other hand, it means there are certain albums that will only ever be allowed to play on my older equipment.

In summary, I deeply enjoy the Tubelab SE. I am pleasantly surprised at both the bass and volume levels available. I can't wait to see how it sounds with proper 300b tubes! (any recommendations)? I may in the future see if there is something I can do to shift the tonal balance a little higher (almost too much bass and not enough treble now).

[cotdt]

Thanks for the impressions!

[lowtherdream]

Nice build acceler8 I cannot enlarge the pictures... is it just my browser?

There are many affordable 300B options:

Electro Harmonix gold pin
JJ
Gold Lion
Full Music
Psvane

They range from $150 to $300 /pair

You can get them from parts connexion for example.

There are many other options when money is no object.

[acceler8]

Originally Posted by lowtherdream

Nice build acceler8 I cannot enlarge the pictures... is it just my browser?

Sorry, I pasted the thumbnail links by mistake. Can't edit my post, so I'll repost the photos (hopefully the right links this time).

[DJNUBZ]

Originally Posted by stonehome

I finished my Tubelab SE it's playing music and sounds great. I have a pair of DIY speakers based on Tony Gee's "Mezzo Galactica" with a sensitivity of about 90dB. It'll play loud. Louder than I listen.
I haven't had a decent amp in a year and TSE definitely measures up to these speakers. The detail and realism I love.

I built the chassis with 1/2" walnut veneer plywood I had and 3/16 aluminum I bought at the scrap yard. The legs were left from an Ikea project. I slotted the aluminum tubing using a router and a jig I made. I got the tubing at the scrap yard too.

Thank you George, for a fantastic amp.

This is one of the best looking amps I have seen. What are the chances you took build pics? If you did I am sure I am not the only one who would like to see how you built this amp chassis.

[amandarae]

Two years and 3 months had passed since ordering my board from George. I finally got the time to build and finished my amp. Nothing fancy, just straight forward TSE 300B.

Some pics with its SSE brother. Picture two shows the provision for connecting DVM (back of 300B sockets) to adjust the current of the output tubes. Potentiometers are below the holes closest to the 5842 input tube for each channel.

[Evenharmonics]

Originally Posted by amandarae

Is power transformer same orientation as output transformers? If it is, it should be rotated 90d.

[amandarae]

Originally Posted by Evenharmonics

Is power transformer same orientation as output transformers? If it is, it should be rotated 90d.

Hello,

Thanks for your concern, but it is not an issue fortunately. I have 0.6mVAC residual voltage at the speaker terminals of the output transformer closest to the PT even when preamp set to almost max (I can barely reach half and it's very loud already at normal listening sessions). I am using 101dB speakers and there's a low hum when I put my ear as close to the driver as possible, from there as I move away about a foot, it is quiet.

Again, thank for your concern.


Abe