SP14 Tube Preamplifier Kit is said to have an awful hum. Let's see what gives.
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- Опубликовано: 30 сен 2024
- This was a kit built by the owner. You can buy these kits online for about $1000 and assemble it yourself. It's supposed to be ultra high-end. As with any kit, You never know what you'll find "under the hood"... but minor mistakes can lead to BIG noise.
I have a SP14 and had hum that I just couldn't get rid of until I separated the channel grounds at the main volume attenuator. The instructions suggest running a jumper between the ground of the two decks (L-R) in the attenuator, for ease of ground wire attachment. Problem is, when you do that you create a ground loop, and get hum. Once those are separated, the unit works great. Took me a long time to find it because of the instructions and lack of a complete schematic in the kit.
That said, it's a clean sounding elegant circuit. I'd recommend it, despite the obvious shortcomings in the documentation.
I also have the SP14 and for the price nothing can beat the quality and sound. Or I should say no sound DEAD quiet. Its a pretty simple preamp. What I like about it, is upgraded caps and upgraded tubes.
It is indeed a nice unit. Not the cleanest assembly by the owner, but the potential is there.
I heard these preamps are supposed to be very good and run with the big dogs
I thought it sounded very good. Tube circuits are less complex than most people think.
If there is hum, is it 60hz or 120hz... Check the heaters ground. If AC heaters, then you can use a 300ohm resistor to ground back to the mains ground transformer takes a lot of that out!
I had the model kit under this one (SP13) and had noise (ground) issues. Followed the wiring diagram correctly but only after rewiring 3 times and changing a couple things did i get it right. I liked the pre so much im considering building this one. Although ive come across a few user reviews complaining about either hum or ground issues. Designer wasnt much help for me, after contacting and relaying my issues the first time he replied that it sounded fine before it was shipped out. Which made me laugh cause i purchased an unbuilt kit 😂. 2nd time i reached out he said there's a few different ways to do the ground plane and i need to use the one that works best for me. I started to think this guy must have someone else doing his emails for him. Normally I'd say run away from a builder/seller like this but its pretty good sound for the money. Plus ive never seen anyone tha has bought a pre built unit have any complaints. His half butt schematics and wiring diagrams i think are the problem. Few double grounds coming in and out to different parts (potentiometers, rca ins/outs) Lots of voltage and signal wires crossing paths or running vertical/horizontal with each other. Again, the preamps sound great for the money when you get it right though.
Sometimes with kit stuff, you just have to figure out what works for you. I build plenty of guitar amp kits, and you get a schematic, a layout diagram, and that's it.
Looks good to me , its probably Aikido , tho i make my own Transformers so in the department of Transformers and Chokes i would make it better , but not everyone can do their own transformers, however anyone can buy 2 and make monoblocks , can be in one box tho , but tubes have to run on 2 transformers .
All youre Audio Equipment , say Preamp Amp Speakers , all of that is electrically connected . So you punch your Speaker you generate voltage , and that reflects like a miror to your transformer , and that reflects it to the other speaker going in the other direction.
So imagine your speakers being a Mirror , electrical mirror to each other .Now you can build a good amp that will minimize this Cross Talk , but ultimately having 2 transformers will solve it .
This is nothing to write home about , but still that is the only way i would do it .
Humorously enough, I saw this AGAIN for repair a few days ago. The owner broke one of the pots.
Im glad yiu uploaded this video. I am currently building this kit. It has a hum too. I hope I can locate it.
In this kit, AFTER I found the hum, I discovered he had the pots wired a bit wonky, so I fixed that too. You want to create ONE unified ground plane... If there's 2, there will be hum. Sometimes you just get a tube that hums, so be sure to weed that out also.
I have one built by an engineer, and I loaded it with Rurrian 1578's and a Bendix 5258. I definitely beats anything I have had at home in 40 years, including units costing up to $8K.
very cool. I was just glad I could help this user.
Why can’t I find a pre amp with treble and bass control I don’t get it please explain
Look into Erhard Audio, he offers a few with tone controls.
No reference to ground...Where does the hum go?!
I like the easy fixes
Oddly enough, I seem to see more simple fixes than tough ones.... Or perhaps I'm just getting better at "smelling" the issues before I see them.
DeadKoby probably just getting better at your job
I've also gotten a bit more daring.... telling myself that it's already broken, and nobody else is going to try....
DeadKoby that’s pretty much how I look at it, I just need to get better at recording videos, need a better camera too!
Our current camera was donated by a viewer, and I am very thankful for that. I make these videos as a public service, as I don't expect any money. Check out estate sales/auctions.... that's usually the best place for a cheap score.
an easy mistake to make
I really wasn't a fan of the wire he used, but I didn't want to be mean to the owner....I just wanted to correct the problem, rather than preach about how I would do it.
@@DeadKoby I know this is an old comment, but I’m interested in buying one of these. What type of wire would you recommend? I’ve got a roll of shielded 2 conductor wire with a lead and a ground. Is there a certain AWG you’d recommend? Also, that input switch looks kinda low grade, but I’ve used the same one in prototype gear. Is there a brand of switch you’d recommend that’s better quality? I’d also do the film cap upgrade. And, one more question, are the RCA input jacks decent quality, or would you upgrade them to something like CMC?
I really apologize for all the questions, but if I build one of those, I wanna get it 100% right. Thanks so very much for the vid. - Nick