I built this TU-8500 Stereo Tube Preamplifier Kit. Now for evaluation

[MX117.MC7150]

Indeed it is. Definitely looks like an opera or tragedy character.

Thanks to you and Hi-Figuy's tip.. Where did you find the grommets and what is the correct size?

 

[sanford12]

Ace Hardware. I took the shaft with me and used the first size that fit loosely on the shaft. Once you get that grommet in the square hole that's only a little bigger than the shaft itself it's a tight fit. I used a little vaseline for lube.

 

[adnick]

I’m also a very slow builder (-; Interested in your thoughts after you put it to some use over time, and which tube(s) you like....

 

[MX117.MC7150]

sanford12 - Thanks, again.
After digging thru my 'stash' I find I have some Syl 12AU7 and JAN Phillips 12AT7 to roll thru mine. Won't be able to answer which sound best until some time in February.

 

[sanford12]

I have some black plate RCA AU's. The pair of 12AT7's I sent for one is great the other must have suffered during shipping both sections are bad so that will have to wait.

Set-up everything anew. I have the preamp on top of the of the CD6006 the ST-70 between the TT and CD. Throw in Sting's Brand New Day. Something isn't right. The overall sound is off. So I'm looking at the pre on top of the CD player and think probably not a good idea to have that preamps transformer on the source. Put the Nak deck in between and sure enough it freed up the sound. Think it's time to try those double mica 12AU7's

Well that was an immediate change. Chuck the Chinese tubes that came with it. The tubes I used are labeled National which is a seller of re-branded tubes and could be any USA/Canada maker but labeled Made in USA. Nice looking double mice tubes. The volume knob was in the same position. There was more gain, clarity and better top end from the get go.

The phono stage. I use a Empire 298 with a low impedance MC Denon 103 cart that will give some phono stages fits. I gave this a listen and it sounded pretty thin compared to the Music Fidelity LX2 phono pre ran through the TU-8500. It wasn't horrible but I'd try some different op amps for sure and will. To me there's no shame losing out to the LX2 as it's a damn fine phono preamp.

I also hooked the Infinite Slope 1.8's up. With the Outlaw as a pre it wasn't good with the
TU-5800 they're sounding just fine.

So far. The 12 volt + - voltages are right on the B+ is 147 where 140 is nominal not really worrisome to me.

It has more bottom end than than most and is well controlled.

I'm going to run it in before anymore evaluation.

 

[MX117.MC7150]

.......................through the TU-5800. It wasn't horrible but I'd try some different op amps for sure and will. To me there's no shame losing out to the LX2 as it's a damn fine phono preamp.
I also hooked the Infinite Slope 1.8's up. With the Outlaw as a pre it wasn't good with the
TU-5800 they're sounding just fine.

Am guessing you are transposing the 8 & 5 and you mean the TU-8500.

I went for the Mundort cap upgrade, so, if anything like the Clarity CMR caps I've used in the past, it will take at least a month of running to get them broken-in.

 

[45rpmspinner]

Chuck the Chinese tubes that came with it.

Not sure if you're being literal, but if you're a squeamish as I am on initial start-up, I suggest saving them.
Great for that purpose. To my mind, better than firing-up an untested board stuffed with nice tubes.

 

[sanford12]

I did it with a new pair of early EH 12AX7's that were total garbage and they were tossed. These Chinese tubes are much better than the EH's were so that's the kinda duty they'll find here.

 

[adnick]

Not sure if you're being literal, but if you're a squeamish as I am on initial start-up, I suggest saving them.
Great for that purpose. To my mind, better than firing-up an untested board stuffed with nice tubes.

Me too, mine are connected to a dim bulb tester, plugged into a variac, plugged into a true isolation transformer! All my variacs also have volt & amp display....

Might be a bit of overkill to some, but I freely admit to doing some really idiotic things at times (-;

Regards,
Andy

 

[MX117.MC7150]

Some have called me a 'dim bulb' (primarily my wife's comments about my stereo hobby), but I've never tested as same..............

With a decent quality (no matter the SQ) tube, no reason to toss. Always good for break-in run-time for caps, speakers, whatever.

 

[sanford12]

Found a pair of good 12AT7's in the tube horde and ran them all day yesterday. I wasn't impressed. To me the 12au7's sound better. It was really rolled off on the highs and just didn't have the same kick with the 12AT7's. This is a really quiet preamp.

 

[MX117.MC7150]

Yep......... the only ears that count are the owner's. All other input are just suggestions on what 'might' work...............

 

[sanford12]

Well it ain't all roses. I'm going to have to go through it and check. Was sounding great then I started the pre the next day and there was no sound stage everything collapse to in between the speakers. All voltages are fine. Time to start checking solder joints.

 

[adnick]

That’s too bad....

Was working on one of mine the other day and a clipped resistor leg fall down and make contact between the line posts, big flash, not good. Plus it’s always worse with something that was just built, just hate to open it up again....

Hope it’s something simple,
Andy

 

[MX117.MC7150]

sanford12 - may be as simple as a tube (where I would start).

Good luck to you and Andy. VictorK is only an e-mail away and is quite responsive.

 

[sanford12]

With the pre it was the same with 3 different sets of tubes. I'll be going through the ST-70's tubes today.

 

[MX117.MC7150]

Good luck.
I've always enjoyed Joseph Audio speakers having owned RM7Sig, then RM7XL followed by RM25XL, which I should have kept.

 

[sanford12]

Started out testing all the tubes and they were all good. So off to the bench. Re-flowed every solder joint, got rid of all the Hersey Kisses looking ones. Found one spot where I had bent 2 legs over which appeared to be touching. Back in and all is well thank goodness. You can hear it get sweeter sounding as things warm up and settle in. Tomorrow I'm replacing the can in the ST-70.

That’s too bad....

Was working on one of mine the other day and a clipped resistor leg fall down and make contact between the line posts, big flash, not good. Plus it’s always worse with something that was just built, just hate to open it up again....

Hope it’s something simple,
Andy

Hopefully the leg took the brunt. Good luck.

 

[MX117.MC7150]

Excellent. Glad it has worked out.

 

[eatabagel]

Started out testing all the tubes and they were all good. So off to the bench. Re-flowed every solder joint, got rid of all the Hersey Kisses looking ones. Found one spot where I had bent 2 legs over which appeared to be touching. Back in and all is well thank goodness. You can hear it get sweeter sounding as things warm up and settle in. Tomorrow I'm replacing the can in the ST-70.

Right now my pre is a $40 FX-Audio tube preamp (hooked up to a Bob Latino ST-70). I am considering getting this kit as well. My only prior experience with kits is the Bob Latino, which took me about a week to build (several hours a night). Would you say that the Elekit TU-8500 is more challenging/more exacting to put together?