I just modded my Danzz board with the snubber mod and Panasonic OSCONS (inductors are coming) and was very pleased with the sound. Then, I saw an Astron RS-20A on CL today for $50 and picked it up. I just plugged it in and OMG: the best sound I have ever heard coming from my speakers! The bass was just pounding me in the chest and the details are just crazy stupid.
But here's the rub: there is a hum coming out of the right speaker (and the Astron is also buzzing a bit when I put my ear up to the unit). What's going on here? I switched power supplies to a laptop brick and it was dead quiet. I hooked up the Astron to my Sure TPA 3110 in my garage and couldn't hear the hum. This is weird. Is it a grounding issue?
But here's the rub: there is a hum coming out of the right speaker (and the Astron is also buzzing a bit when I put my ear up to the unit). What's going on here? I switched power supplies to a laptop brick and it was dead quiet. I hooked up the Astron to my Sure TPA 3110 in my garage and couldn't hear the hum. This is weird. Is it a grounding issue?
How close is your amp to the Astron? Big transformers have big stray fields, so you may need some distance. Does the Astron also buzz without a load? Transformer mechanical buzz is not uncommon (generically speaking, nothing to do with Astron per se).
BK
It was about three feet. The Astron buzzes without a load. I thought it wasn't a good idea to have long power cables to the amp. Maybe I got that wrong. I will try moving it around.
3ft is more than enough to avoid stray fields - I was just making sure it wasn't stacked directly on top of the Astron. Make sure your RCAs are also not up against the PS transformer. To help isolate speaker hum origins you can short the RCA inputs and listen for it again. Is your hum-less brick a 2-prong type?
BK
Thanks for your help. I really do appreciate it. The hum-less brick is three-prong; the same as the Astron. Now that I am thinking about it, I should have mentioned the board has not been housed yet. Could that be part of the problem? The Sure board I tested without hum is housed in an aluminum Hammond chassis. But why just the right channel?
I don't have enough experience with the TPA amps to predict if casing it up might help. For quick and dirty tests I'd short the inputs first to exclude your source components, then if you're comfortable with the safety implications temporarily lift the ground on the Astron to see if it makes a difference in the hum. Only one channel could be your input/pot wiring, recent modifications, etc.
BK
My friend Nikhil invited me over to try my modified YJ TPA3116 blue amp with his Altec Model 19 monitors. These are some of my favorite speakers, and I would have a pair if my living room was large enough for them. Any, I packed up my amp, upgraded Astron RS-12A power supply and some choice vinyl and headed across the bay to my friend's house.
My friend's systems consists of the following components:
Needless to say, his system sounded great. I've always been impressed with the 6B4G P-P running NOS Sylvania 6B4G tubes. We played Oliver Nelson's "Blues and the Abstract Truth." On "Stolen Moments," we could hear Eric Dolphy draw his breath as he played the flute. The soundstage with these Altec speakers is incredibly huge and life-sized.
We removed the 6B4G amp and inserted the modified YJ TPA3116, which I refer to as Frank (short for Frankenstein). After several minutes, the sound really settled in and we both marveled at the large soundstage that the Class D amp could cast. The separation was incredible, especially when we played Remembering Shakti's "Saturday Night in Bombay." each musician held his spot on the stage and the system was able to capture the dynamics of the percussionists faithfully, along with John McLaughlin's virtuoso guitar playing in perfect time with the other musicians. As great as the TPA3116 played, I still have to give it to the 6B4G amp for tonality. This amp has a palpable midrange that coveys a convincing presence in the music.
Still, I have to say that the CineMag input transformers have really made a significant improvement where I am comparing this amp to a very expensive P-P amp.
My friend's systems consists of the following components:
- Empire 208 belt drive turntable with RS Labs RS-1A tonearm and Genesis MC cartridge
- DIY D3A tube phono stage designed by Andrea Ciufolli
- Emotive Audio Erato tube line stage
- Tube Audio Lab 6B4G P-P tube amp custom built by Min
- Altec Model 19's and Quad ESL-57's
Needless to say, his system sounded great. I've always been impressed with the 6B4G P-P running NOS Sylvania 6B4G tubes. We played Oliver Nelson's "Blues and the Abstract Truth." On "Stolen Moments," we could hear Eric Dolphy draw his breath as he played the flute. The soundstage with these Altec speakers is incredibly huge and life-sized.
We removed the 6B4G amp and inserted the modified YJ TPA3116, which I refer to as Frank (short for Frankenstein). After several minutes, the sound really settled in and we both marveled at the large soundstage that the Class D amp could cast. The separation was incredible, especially when we played Remembering Shakti's "Saturday Night in Bombay." each musician held his spot on the stage and the system was able to capture the dynamics of the percussionists faithfully, along with John McLaughlin's virtuoso guitar playing in perfect time with the other musicians. As great as the TPA3116 played, I still have to give it to the 6B4G amp for tonality. This amp has a palpable midrange that coveys a convincing presence in the music.
Still, I have to say that the CineMag input transformers have really made a significant improvement where I am comparing this amp to a very expensive P-P amp.
Thanks Destroyer,
sorry to be stupid, but can you post a circuit schema?
What can be the capacitance ?
another question: I understood what you say about current protection, so, what current limiter do I need ?
3 questions 🙂
thanks for your answers
You said the Astron hums without a load, but not in your garage, right?
What else is plugged into the circuit (in your house) that causes the Astron to hum?
I used to have this laser printer that draws a lot of current when it starts up. It always caused my computer's UPS (uninterruptable power supply) to hum. I noticed it also caused my Astron power supply to hum.
Apparently, that printer drew enough current to cause the voltage to sag. At least with the UPS, it causes the voltage regulation coils to work hard to maintain constant voltage. Presumably the Astron is doing something similar.
I put a DMM on my outlet when the printer fired up and could see it drop a bit. You might see what the voltage on your outlet that causes the Astron to hum is (versus the voltage in your garage, which is likely to be a different circuit).
Rhing,
First of all, kudos to Nikhil - he has put together a very nice system! 🙂
Very good summary and what you have described pretty much sums up my experience with good tube amps and good Class D. A good tube amp can convey more of that "real" presence of music; that can make it addictive, especially for music that is not very complex. However when it comes to separation of different instruments, dynamics, and bass articulation - a good Class D amp does it very well.
More incentive to build a decent power supply unit (if Destroyer OS is kind enough to share details - have sent him a PM). And maybe the Cinemag or Jensen transformers if funds and time allow...
Did Quad ESL impedance dip trigger TPA protection? If not how did vocals sound on ESL ?
I didn't dare try the TPA3116 amp with my friend's Quads. Something would go awry with that setup. My sole objective was to try the TPA3116 amp with the Model 19's and it performed exceptionally well.
That's a fair statement. My friend's system is built around tube amplification. His 6B4G amp uses a pair of Lundahl LL1692A interstage transformers and a pair of Sansui 1000A output transformers. I would expect a tube amp like that to outperform the TPA3116 amp. I think what's impressive is that I would even think of comparing a relatively cheap Class D amp with a tube amp with great results.
As for off-board cap banks, I used to have four 2,200uF/25V Panasonic FM caps connected to my amp. I've pulled them out, because I found that the bass was too heavy and masked the mids and highs. My Astron RS-12A linear supply upgraded with a Kemet (Rifa) PEH200 filter cap, a Nichicon KZ filter cap and a Panasonic FM filter cap gives me plenty of bass and dynamic slam. This power supply and amp combination had no problems driving the Altec Model 19's 15" woofers.
Shorted the inputs and still got hum. Took a stock board to see if it was my mods producing the hum (the snubber grounds are close to dc power traces) but still hums. Lifted the ground on the Astron by using a two prong adapter and no hum! WTF? I understand so little about power, but why would the ground produce the hum? I just had an electrician properly ground many of my outlets in which electronics are plugged (including where the Astron is plugged). So for the added safety, I now get crappy sound? Great. I'll go with sound every time. Thanks again for the help!
This inbetween ground on cord and Astron should eliminate hum while retaining safety. It's made for this specific issue.
DENO-25-0001 Schurter | Mouser
DENO-25-0001 Schurter | Mouser
Thanks! Will order when I need more parts for these projects which seem to grow week to week.
Excellent trouble-shooting! Some form of "ground loop breaker" should get you squared away and retain all safety. Tracking down and resolving household ground issues related to audio can be a real rabbit hole. I suppose we can't really rule out something funky with your particular Astron, but maybe that's now moot...
BK
It's just ten 2200 uF caps parallel together. Negative sides on the middle for easy soldering. 😉
