Question from owners of the Dayton HTA100BT hybrid amplifier

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Brent3Cats

New Member
Anyone with the newer version of this with the Phono stage built in?

With nothing hooked up to the phono input - no rcas or ground wire - there is what sounds like a 60hz hum that gets louder with the volume knob. Not loud, just there but definitely noticeable between tracks.

The Bluetooth and auxiliary inputs have no audible background hum / noise at loud volume.

When hooking up a turntable and grounding it to the amplifier there is no additional and no less hum/noise than with nothing hooked up and the input switched to phono.

Anyone with this amp - do your units do this? Is this an issue with mine or just the amplified noise floor from the high preamp gain required for phono carts in general?

Thank you very much if anyone sees this and can answer my questions.
 
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I suspect it's a byproduct of the high-gain, equalized phono preamp circuit.
Are you testing this with the inputs "open circuited"?
The important test would be the hum/noise level either with shorted inputs (which is usually the way the S/N of a phono preamp would be tested, AFAIK), or (at least) with a turntable hooked up to it (and also with or without a ground in place; the quietest implementation of a phono section in terms of hum won't always be the one with a ground from tt to amp).

Or, it just may be a noisy preamp/EQ. It's a very cheap component.
 
I do not have shorting plugs so I have only tested with open/nothing in the inputs, or the turntable itself attached. I figure it may be normal and for the price of the unit its not the end of the world. When I called parts express they gave me a runaround answer. (loud enough you will hear some noise on anything. if you want to warranty it you can but the next unit may be the same and ill be out a unit for a while, etc) He also advised that I check my power source for a ground loop issue. I suspect this not to be the case since it only happens on one input and not a hum in the amplifier all the time.

With the rcas hooked up and not using the ground wire there is definitely a bad buzz and a earth connection issue

There is a five year warranty on it so I am in no rush to figure this out. There are not any video reviews of the amplifier on youtube and the product is fairly new so I cant find much about the phono stage on other forums.

I don't have very much experience with phono preamps in general so I don't have a good reference for what is "acceptable" noise in budget equipment.
 
So, with the tt hooked up and a ground connected 'twixt tt and amplifier -- how is the noise/hum under the same conditions as your "open circuit" test? Similar, better or worse?

If it's better -- you're done.
If it's the same, or worse and if you find the noise level objectionable at your typical listening levels -- you might want to return the amp and try something else a little higher up the quality (and cost) food chain.

The moving magnet phono preamp is a high gain device, and it also applies a steep equalization curve to the output of the phono cartridge. Records are made with a equalization curve that boosts the treble and reduces the bass, relative to midrange (RIAA equalization), and a mirror image EQ by the phono preamp circuitry is applied for "flat" playback (see the curves below in the figure borrowed from Wikipedia). You can see how low frequency noise and hum might get enhanced, if it comes from somewhere "upstream" of the EQ stage in the preamp.

1280px-RIAA-EQ-Curve_rec_play.svg.png


A low price phono preamp is almost going to be noisier than an expensive, higher quality preamp -- and even a high quality phono preamp won't be dead quiet (at least compared to a "line level" component's S/N).

One possible non-example (I haven't heard one) is the Parks Audio "Puffin" (outboard) phono preamp, which does its signal processing in the digital domain. The S/N is probably considerably better than the traditional "phonostage". It's not even particularly expensive! :) http://parksaudiollc.com/
 

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I have ordered some shorting plugs and a double shielded RCA cable. I tried my really cheap rca cable and they seemed to have more noise and I could touch the cables and the noise would change on the bargain bin cables. I am going to test tomorrow night when all of it comes in.

I looked at that puffin phonostage and that might be the coolest phonostage I have seen! One day maybe I will pick it up but I am remodeling my house so the fun budget is quite low at the moment. Most good phono preamps cost the same as the Dayton integrated amp so If I can get this electrical sounding hum gone I am content with the sound quality otherwise.
 
Quick update: Shielded RCA cables made hum marginally tamer but still not ideal. I grounded the turntable to the earth pin on my power strip and no better. I am getting a new amp sent to me from parts express and I am shipping back the old one. If the new one does it at least I will know for sure that it is normal.

If it does still hum I will save up and get a Schiit Mani but keep the Dayton as the power amp. Other than the noise on the phonostage the amplifier has exceeded all of my expectations in terms of sound quality and how full of a sound it produces. It sounds much nicer than my 90s Technics AVR that sounded pretty decent until it died. The auxiliary RCA input is really clear compared to the old setup.

One day I would like to have Puffin DSP -> PS Sprout -> Klipsch RB-61ii + Emotiva SE12.
 
could be ground loop or could be endemic to the component you're using. :(

For ground loop troubleshooting -- start with the simplest possible system (amp and speakers), check for hum. One at a time, add back components and listen for changes in the baseline hum.

One may also "lift the ground" of any three-prong plug with a "cheater" to see if that changes the hum level -- this is for testing purposes only, as, obviously, someone included a three-wire power connector for some reason (safety/code compliance)... but the issue of multiple grounding points in an electrical circuit (e.g., a hifi) can "induce" problems of its own... and troubleshooting groundloops is both art & science. :confused:
 
My setup is:
Turntable -> dayton integrated -> speakers
I will try a cheater plug on the integrated and on the surge protector (the only parts of the setup with 3 prong cables. Ill see where that gets me tonight!
 
Brent3Cats said:
My setup is:
Turntable -> dayton integrated -> speakers
I will try a cheater plug on the integrated and on the surge protector (the only parts of the setup with 3 prong cables. Ill see where that gets me tonight!
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You might want to try bypassing the surge protector, too, as you troubleshoot.
It may well be that the amp is just... noisy. But it could be something else in the chain.
 
Not sure if anyone is still interested in this post but...

I've also had this amp for about 6 months, now, and am still experiencing exactly the same thing as Brent3Cats. I have tried EVERYTHING and nothing has eliminated the hum. I have tried grounding, not grounding, power conditioner, no power conditioner, different table, different phono and different amp. The different amp I tried was a 2nd generation Manley Stingray and the hum was nearly inaudible with all of my other components in line. But the Stingray is not mine so I deal with hum. Interestingly enough, when I hooked up a sub, the hum noise improved (lowered) noticeably. The hum was originally present at 11 o'clock on my volume dial but now it's not audible til 2 o'clock (forgive me, but I do not have meters to measure SPL or frequency response). I have also noticed what sounds like a fan in the amp clicking on and off and it is LOUD! I also did not pay close attention to the specs when considering the amp and realized it advertises as 50wpc into 4 Ohms, and my speakers are 8 Ohm nominally. The amp does not play very loud and I am reluctant to push it past noonish on the dial.

I have concluded that the amp is the weak link in my system, and I am already looking to replace it. I am not knocking DA or the amp - it is what it is and I did not expect much at its price point. I was just looking to dip my toes back into the game a bit after two decades and go from here.

Troubaudior

System:
DA HTA100BT
PSB Alpha P5
Sony 100wpc sub
Technics A10 DVD-A/CDP
Sony SACD/CDP
U-Turn Orbit table
Toppings DAC hooked up to laptop for streaming and saved music files.
 
There are lots of free SPL (sound pressure level) apps for Android and iPhone. The ones for iPhone are probably more accurate as they only do iPhones.

I have one (Sound Meter) installed on my Samsung phone.

There are also free spectrum analyzer apps available.
 
Another option if you like how the amplifier sounds is to add a stand alone phono preamp. It sounds like the phono stage is the weak link here. The hum is probably due to the power supply to the phono section, shielding, wire routing or ground loop.
If the input to the phono is too close or parallel to any AC wiring you can get hum. Another thing I see with some of these PCB's is the ground plane. Some wrap all the way around the board and create ground loops. Cutting a ground trace at the right spot can reduce or eliminate hum. But you would need the schematic to see where would be best to cut the trace. More than likely it is a ground loop problem. There are some decent stand alone phono preamps that won't break the bank. If you need more inputs adding the phono preamp just add an input selector to the aux in on the amp.
 
JoeESP9 said:
There are lots of free SPL (sound pressure level) apps for Android and iPhone. The ones for iPhone are probably more accurate as they only do iPhones.

I have one (Sound Meter) installed on my Samsung phone.

There are also free spectrum analyzer apps available.
Click to expand...


Ha! I should have know that "there's an app for that!" LOL!

Thank you so much for the tip, JoeESP9 ! I will certainly check out the apps for iPhone!

Troubaudior
 
Lavane said:
Another option if you like how the amplifier sounds is to add a stand alone phono preamp. It sounds like the phono stage is the weak link here. The hum is probably due to the power supply to the phono section, shielding, wire routing or ground loop.
If the input to the phono is too close or parallel to any AC wiring you can get hum. Another thing I see with some of these PCB's is the ground plane. Some wrap all the way around the board and create ground loops. Cutting a ground trace at the right spot can reduce or eliminate hum. But you would need the schematic to see where would be best to cut the trace. More than likely it is a ground loop problem. There are some decent stand alone phono preamps that won't break the bank. If you need more inputs adding the phono preamp just add an input selector to the aux in on the amp.
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Thank you for the reply, Lavane. Yes, the thought of adding an external phono pre did cross my mind, but I am seeing more and more limitations on the DA amp as a whole. So I'm already beginning to eye better amps.

The Rogue Sphinx being one. Bit out of my price range but may worth it in the long run. Gee, how many times have I told myself that? LOL (read my post in intro).

Troubaudior
 
TROUBAUDIOR said:
Thank you for the reply, Lavane. Yes, the thought of adding an external phono pre did cross my mind, but I am seeing more and more limitations on the DA amp as a whole. So I'm already beginning to eye better amps.

The Rogue Sphinx being one. Bit out of my price range but may worth it in the long run. Gee, how many times have I told myself that? LOL (read my post in intro).

Troubaudior
Click to expand...
Rogue makes some very nice equipment and from all I've read from owners that have posted about them support is really good also. I came this >< close to buying one of Rogue's tube power amps. I couldn't build one with all its features any cheaper. I wound up building a couple mono block amplifiers instead, only because I enjoy building equipment. I didn't save anything doing it.
 
Lavane said:
Rogue makes some very nice equipment and from all I've read from owners that have posted about them support is really good also. I came this >< close to buying one of Rogue's tube power amps. I couldn't build one with all its features any cheaper. I wound up building a couple mono block amplifiers instead, only because I enjoy building equipment. I didn't save anything doing it.
Click to expand...

Interesting you mention that building one yourself was not cost effective when compared to RA's price. I have a friend who's an EE (and occasional audiophile). He wanted to build amps for him and me, thinking we could get way better quality for the same (or less) money. But that did not turn out to be the case. A quality power amp was still costing him/me about $800US when all was said and done. According to him, he couldn't get the deep discounts that typical audio companies probably get from buying in bulk.

Thanks for responding.
 
TROUBAUDIOR said:
Interesting you mention that building one yourself was not cost effective when compared to RA's price. I have a friend who's an EE (and occasional audiophile). He wanted to build amps for him and me, thinking we could get way better quality for the same (or less) money. But that did not turn out to be the case. A quality power amp was still costing him/me about $800US when all was said and done. According to him, he couldn't get the deep discounts that typical audio companies probably get from buying in bulk.

Thanks for responding.
Click to expand...
Yup. It just came down to I couldn't build what I wanted much or any less. You can get away with it with smaller amplifiers, but the bigger ones not so much. I decided on kits since I like building them, and I was able to make a few modifications. Just look at the prices for comparable equipment made by other companies. Rogue seems to check off most or all the boxes for less.
 
Lavane said:
Yup. It just came down to I couldn't build what I wanted much or any less. You can get away with it with smaller amplifiers, but the bigger ones not so much. I decided on kits since I like building them, and I was able to make a few modifications. Just look at the prices for comparable equipment made by other companies. Rogue seems to check off most or all the boxes for less.
Click to expand...

Yes, that is what I am finding with RA, too. Truthfully, I'd prefer an all-tube integrated. But I am having a pickle of a time finding one with decent specs that has enough power to drive the PSB Alpha P5s, which hang around nominally at 6 Ohms and are rated at 89dB. IIRC, the Sphinx' specs rate it at 100wpc into 8 and doubling into 4 with a tube pre - all for $1200US or so for new one, less for used. Hence why it's at the top of my list. If you have any insight into an all-tube amp with power and decent specs, please share!

Thank you, :Lavane!
 
The Rogue Audio Atlas Magnum is the 100wpc Tube power amplifier is the one I almost bought. But higher powered tube amplifiers do get expensive. A lot of people run tube preamps with SS amplifiers. I've done it. A good SS power amplifier shouldn't sound like anything. It's job is just to amplify the signal fed to it. The Tube preamp would set the overall tone.
 
Lavane said:
A good SS power amplifier shouldn't sound like anything. It's job is just to amplify the signal fed to it.
Click to expand...

I completely agree. That has been my experience with high-quality SS power amps, especially my beloved Threshold T-200. But like expensive tube-power, a good SS power amp that does that what you say also becomes pricey. I think Rogue gets away with it at their price point on the Sphinx because of some new-fangled way they are implementing Class D amplification to mimic Class A operation? At least that is how I interpreted their explanation on their website. I'm not an EE so much of it is lost on me.
 
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