TC-750 Phono Pre-Amp (Continued)

Stage 1 newbie question - trying to hook up my Sola power supply. Cut the end off from a power plug. Black (hot), white (neutral) and green (ground) wires. Input on the Sola power supply says connect the ac to 1 & 4 - with jumpers across 2&4 - 1&3. How does this correspond to my power cord? Assuming the black goes to 1, green to 4, and white neutral to 5, but its just a guess on my end.

 

Here a bit more progress...

Getting ready to install caps. Wires on the caps were much too thick to go through the pc board, so I tried this method of extending the through hole locations with some left over wire.


Caps installed - huuuuge guys. Everything seems to be in place, all modifications to the TC-750 are complete.

Now time to figure out power supply, almost ready to power up and test it out. Limited info online of wiring this up (see above post). Should be able to figure it out soon enough and actually try it out tomorrow.

 

I only hooked up 2 wires, the flat prongs, not the round ground prong, and If you look at @purrin's first post you will also see a pic with only 2 wires attached to 1 and 4. I suggest you cover the exposed wires and jumpered pins with electrical tape so it doesn't short out. A short wouldn't be good, you're playing with household A/C. Be careful...

Nice work, it looks like the TC-750 went full beast mode !!!

Did you try the TC-750 stock to get a feel for the original sound?

 

AAAHAHAHAH! No such thing as too much, huh?

 

With @JK47 helping me out, I am up and running.

I did do some quick initial impressions before modding, but thought my phono box ds sounded better and moved on. The phono box had more detail and clarity, the 750 sounded a bit dry?. My objective was to best the phono box (and sell it).

The modded 750 sounds fantastic. Gobs of detail coming through my hd650's that has not been there before. Tonal quality changed significantly, more bass, more detailed bass, tighter mids, etc etc. Sounds much better than the phono box ds.

Don't have much to compare it to on the higher end of pre's. I just really am impressed with how engaging this thing is.

Next - how the hell do I cram all of this into a case? Will probably see if i can fit ot in the case i have for now, jusy leaving the cover off. Although, may stay lazy and just enjoy listening for a bit (really like how this sounds)

Thanks for everyone's help on this - this is what makes SBAF great to me. Could not have done this with out you guys, or even know that I could do it. I'm left feeling like I have a top end phono stage plus a good learning experience.

 

I've been playing around with my new turntable, SUT, and the Franken TC-750 over the last few days trying to get the hummm down to nothing. First step was to remove the ground from the TT to the SUT, which was a noticeable difference in the right direction, maybe because the VPI has a 3 prong cord? I tried removing the ground from the SUT to TC-750, not good, big big hummm. With the TC-750 and SUT the humm wasn't too bad, but would fluctuate depending on where I walked in the living room with my headphones. I tried fiddling with positioning of the TC-750 and SUT, the only thing that seemed to make a difference was when I jiggled the TC-750 outputs. I took a closer look, and the outer ground jacket of the RCA terminal looked like it was touching the foil and grounding itself to the chassis, which almost completely eliminated hummm altogether. I soldered a few wires from the output RCA terminals to the chassis ground, and voila, hummm is non existent at listening levels, and near nothing all the way to max.

 

Nice... I noticed mine is super picky if it's near other electronics... especially my wireless router. I ended up moving the router elsewhere and it stopped picking up a hum. It was super weird - depended on which direction the 750 was facing. Glad you got yours sorted. I will have to come listen sometime JK... is your setup in Fort Mac or Calgary? I've moved east near Toronto, but we'll have to get together for a meet sometime.

 

I only work in Ft Mac (for how much longer I don't know...), I live in Billings Montana. Probably moving to the west coast by end of the year. Going to visit my friend in Orange County next month, and check out a few spots. Give me a holler if you're ever in the area.

 

Finally got my TC-750 cased up. First real casing project I've done - critiques are welcome. Feel like I've learned alot and would do things differently on the next case. This was really just a test project, as this pre will shortly be replaced by a P Millet LR Capacitor-less pre, just waiting on Cinemag inductors.

Ran my Pro-ject Phono Box DS for the last week or so while I had everything dismantled, and really made me appreciate this "Franken-TC750". SO much more body, fuller sound, better on the low end and detailed than the project box. I have not listened to a large variety of phono pre's, but this pre and my debut carbon are preferred over my Gungnir Multibit / mutec 1.2.

Redneck Efficiency at its best. Lets take a small cheap box, rip it apart, buy parts more expensive than the origional unit, put a oversized motor in 'er, make it 6 times larger and be stoked with the results.

Start point (before steroids)


After (next to bottlehead crack for size comparison)


Guts


Booty


$50 for TC 750, $35 for Sola LPS, $50 for case, $150 for caps, $20 misc wire and parts. Total cost is roughly $300 or about what I paid for the project box.

Probably done with mods on this, but could see myself going back and putting a on off switch or a power led on the front.

 

How about some Black Gate 10uf 250V for the input caps? They sell for $5.50 a piece at Percy Audio: http://www.percyaudio.com/Catalog.pdf (page 7).

 

Hello everyone! This is my first post on Super Audio Friends. I will introduce myself, I have a modest setup at home: Psb tower speakers, Denond AVR4806 and Pro Ject Debut Carbon with stock cartridge and SpeedBox. I want to improve my Denon pre amp sound, or just start to experiment with audio DIY (I have some experience building a DIY synth) and I saw this page, since I recently purchased a TC-750 for my secondary system (Technics SL-D3 turntable).

However is that I was trying to get SOLAHD power supplies but the cost here in Mexico is prohibitive, are there any other options for a good power supply you could recommend that I can order on sites like Mouser? Thank you in advance for any advice!

 

thanks for the advice!

 

Which PSU is the best so far?

 

So, for the case for PSU only, I think this is perfect. With some horizontal space left for cabling and other stuffs.

http://www.mouser.com/ProductDetail...=sGAEpiMZZMsrGrAVj6eTvXcJO6AATeuQOaVWM5pyQQM=

 

I have one of these now, I can say with the utmost certainty, it's lightyears ahead of the Music Hall it replaced. Much less veiled. I'm starting to think most vinyl-heads, at least elsewhere on the internet, are huge warmfags.

I've pulled out the cart loading caps, 1K base stoppers, then started playing with cart loading resistors. Tried 90K, currently at 45K, will try 60 in a bit. I'm starting to think, even with the AT440MLB (read bright), the default 47K is just fine as long as you pull those 220pF loading caps.

Likely going to try some WIMAs for in/output caps as well as the suggested SOLAHD power supply.

 

British speakers followed that as well for a while. I don't quite think they much like treble or bass without that prominent 100 Hz bump.

 

Ordered one myself (current phono I was give has a dead right channel), hopefully it'll be here by Saturday. I'm gonna give it a week or two of listening, then look into swapping caps / PSU mods.

 

This post details my epic saga with the TC-750, the "little phono that could". If you want to skip to impressions, feel free to scroll past my verbosities and indulge yourself down below.

My current rig (fairly basic setup):

Ortofon OM5e cart > U-Turn Orbit TT > modded TC-750 phono > Parasound P/LD-1100 preamp > Parasound HCA-1000a power amp > modded ELAC B6 speakers

Prologue

After much research and debating, I got into vinyl earlier this spring of 2016 with the Orbit Plus. I immediately bought the TC750 phono which provided nominal gains over the built in phono of the vintage sony receiver that I was currently using (or I was too much of vinyl noob to discern much difference). Besides, I never bothered to really ABX them, so who knows and who cares, life is too damn short.

Shortly after, @OJneg sold me his modded version of the TC750 with the mods detailed below (also explained in the first page of this thread).

So the phono arrived sans AC adapter because OJ previously had it hooked to a sigma11 PSU. No problem, I thought, so I tried using the stock piece of crap adapter that came with the stock TC750 I bought weeks before. Nope, no good... there was a loud obnoxious underlying hum (OJ says most likely from the excess power supply parts being removed from the board to accomodate better power sources). Sooner or later, I knew I had to build myself one of those power supplies detailed in this thread, but my DIY skills at the moment were limited.

Anyway, I soon got too busy with applications and life, so the modded TC750 was set on the backburner, while I continued to use the stock one.

Modded vs Stock boards

modded TC750
Notice the silent revision between the two boards, seems like they moved around some of the power supply parts (which are removed in the OJ's modded version). Also notice some caps have been switched out for WIMA film ones.



stock TC750



SOLAHD power supply or no?

Eventually, I knew I had to learn how to build a power supply for my modded TC750. I began researching other options as well, and saw some members on audiokarma reporting success rigging a 12V 7A battery to their phono and noticing some substantial gains. The battery looked easy enough, just a couple wires and a connector and minor soldering... I figured that I could give that a try and began gathering up the materials. Long story short, the connector (which I bought from China) still hasn't come, so I grew impatient and bought the "upgraded AC adapter" from the folks who sell the TC750. $15, not bad.

AC adapter comparison



Stock AC adapter on bottom: 12V 500mA
Upgrade AC adapter on top: 12V 1.5A
Soon to be built battery (not pictured obviously): 12V 7A

Impressions

Stock TC750 + stock adapter: my reference for the past half year; really got the job done. Classic rock and jazz (which sounds great on anything) sounds great. Midrange magic at work here, coming from Modi Multibit, Norah and Amy Winehouse... can't complain too much here. Extensions on both ends pretty lacking, especially bass sounding fairly anemic. Overall macrodynamics feel a tad bit veiled. Amazing analog depth and imaging which you can expect from any vinyl rig, no matter how basic. Just sold to @Gaspasser, and I'm hoping he enjoys it as much as I did. And there's always room for improvement when he decides to mod it!

Stock TC750 + upgraded adapter: more juice = heavier punch on the low end, a bit more dynamic, some more plankton coming through. Imaging is a tad bit sharper. For the money ($15) highly recommended.

Modded TC750 + stock adapter: the hum is too damn unbearable, never really listened for longer than 10 seconds LOL

Modded TC750 + upgraded adapter: das it man! Compared to the stock phono with stock adapter, this is really night and day. Better extension on both ends---finally got my bass on the analog rig! Low end is now hefty compared to before. Veil now lifted. Amazing detail retrieval and clearer imaging, even on my basic cart/TT, I was afraid that I was on a goosechase upgrading my phono with a budget table... but the differences are real. Better macrodynamics, everything just sounds larger. Background is blacker, and the annoying hum is essentially gone (it's very faint even when I have my volume maxed out, but no one really listens this loud). Really glad it all worked out with the modded TC750, now I can enjoy my electronic records even more. Not to mention that it does wonders for all my other records. I really feel that my vinyl rig is quickly closing in on my Modi Multibit; as I continually upgrade and tweak it, there's less and less Modi Multibit does better.

Modded TC750 + big ass battery: to be continued...