Stereo Amp

[Skip Ellis]

I guess this is the place for this. I'm sort of in a search for a budget (as in cheap) stereo amp/tuner to use with an older pair of Sony bookcase speakers that I've got sitting around. Should be able to accept input from cd player/phone/tablet/Bluetooth. Don't need anything elaborate - just would like to occasionally sit in my recliner and listen to the gazillion Mp3 and wav files I've collected over the years. Would rather hear speakers than headphones or ear buds. I found a little Pyle unit on Amazon that looks like it would do the job but the reviews were not encouraging. Any suggestions? Budget probably <$100.

[nevershouldhavesoldit]

I reviewed class D amplifiers for audiophilestyle.com a while back (link). While doing my research, I bought a Pyle PDA29-BU6. It's $50 now (it was $33 when I wrote the article!) and does everything you want it to do and a lot more. I loved it so much I kept it (I usually sell my test stuff as soon as the aritcle is written). It's an amazing little device that sounds fantastic and has ample power. I took it apart, and it's also amazingly well made - especially for the price. I've even used it as a stereo guitar amp through my two Toob Metros with my Zoom MB60 stereo effects pedal - and it was amazing! I'd ignore those reviews and give it a shot.



[For reference, my main listening system is a Thorens TD125 / SME t'table, Parasound preamp, a variety of DACs (SMSL, iFi, Emotiva), a Prima Luna tube power amp, and a pair of Focal tower speakers.]

[st.bede]

I reviewed class D amplifiers for audiophilestyle.com a while back (link). While doing my research, I bought a Pyle PDA29-BU6. It's $50 now (it was $33 when I wrote the article!) and does everything you want it to do and a lot more. I loved it so much I kept it (I usually sell my test stuff as soon as the aritcle is written). It's an amazing little device that sounds fantastic and has ample power. I took it apart, and it's also amazingly well made - especially for the price. I've even used it as a stereo guitar amp through my two Toob Metros with my Zoom MB60 stereo effects pedal - and it was amazing! I'd ignore those reviews and give it a shot.



[For reference, my main listening system is a Thorens TD125 / SME t'table, Parasound preamp, a variety of DACs (SMSL, iFi, Emotiva), a Prima Luna tube power amp, and a pair of Focal tower speakers.]

A few questions: wieght? And how robust is it? Output connection… the manual did not answer these questions… they even had a blank spot for the output, just stating for speakers…

Thank you.

[nevershouldhavesoldit]

A few questions: wieght? And how robust is it? Output connection… the manual did not answer these questions… they even had a blank spot for the output, just stating for speakers…Thank you.

It weighs 2.5 pounds. The speaker terminals are simple push strips - here's a shot of both front and back.



I use flexible wire end terminals for these connectors:



The amplifier seems quite robust. I've even gigged with it through a pair of Toob Metros running in stereo (driven by the stereo outputs from my Roland GR20 synth), just to see how it handled the task - and it was stellar! It feels pretty solid, and as I said in my first post about it, the insides are very well organized and assembled. It's hard to believe it cost me $33 new and is still only $50.

It's not McIntosh, but it does the job!

[st.bede]

I decided to buy a pyle. I going to use it until I replace the SD powerstage. Now I have to figure out how to get the cables. Typical I just grab speaker cable.

I think I have it all figured out. Flex pin are just screw in… so I think I can take a couple of my speaker cable and get some flex pin thing and just unhook one end from the ts and hook up the flex pin.

[st.bede]

I have it …. EDITED as not to confuse people. I was doing things wrong.

(See below for more information from someone who knows how to do things.)

[nevershouldhavesoldit]

The volume for the rca was low, but I would assume that my preamp would be a good way to address that problem.

The RCA inputs are line level. They require preamplifiation to get the voltage high enough to drive them - you'll get no usable sound running an instrument pickup or mic into them. They take my Crate Acoustic stereo preamp and my Zoom MS60B just fine, but any active preamp would overload a mic input and cause intolerable distortion.

There are many brands of flexible wire termination connectors you can use. I put a set of Monster Cable Flex Lock terminals on one end of the wires I use with this, along with 1/4" plugs on the other end. The Flex Locks are a tight fit into the push-lock terminals on the Pyle - I had to crush and fold them axially with a flat pliers to make them small enough. You can also simply tin the tips on the amplifier end of the wires with solder.

[st.bede]

The RCA inputs are line level. They require preamplifiation to get the voltage high enough to drive them - you'll get no usable sound running an instrument pickup or mic into them. They take my Crate Acoustic stereo preamp and my Zoom MS60B just fine, but any active preamp would overload a mic input and cause intolerable distortion.

I am not doing things right.. it is obvious… line level is the issue here. I figured it out.

[st.bede]

It sounds remarkably good … guitar, into jhs clover, clover into pyle. It is even taking a ts9-clover-pyle really well. It is completely usable.

[st.bede]

I just found and bought a used voodoo lab giggity, (at a good price) so I can have a second small pedal pre-amp, for stereo.

[st.bede]

I know I am crazy… and sometimes I write before I have thought things out…

I have the pyle running mono. It is not that loud. Can I bridge it?

(I am assuming if I run it in stereo (it should be louder… but I am waiting on a second preamp pedal).

[nevershouldhavesoldit]

I have the pyle running mono. It is not that loud. Can I bridge it?

No. The topology of most class D amps makes that impossible. Even though I think it's theoretically possible to build one that can be bridged to mono, I've never seen one that could be.

(I am assuming if I run it in stereo (it should be louder.

That depends on what you mean by "run in stereo". I haven't used mine with my guitar in a few months, so I don't remember for sure whether input from either mic jack went to both channels. My recollection is that it did, but I'll give it a try later to see if that's correct. If, as I recall, input through one mic jack does go to both channels as a mono signal, there will be no increase in loudness if you either split the signal and run it into both mic jacks or run a second signal through the second mic jack.

If by "run in stereo" you mean driving both channels as opposed to one, yes it will be louder - but barely. Doubling output power into identical speakers results in a 3 dB increase.

[starjasmine]

A quick test: try other speakers. Speaker efficiency can make a huge difference.

[st.bede]

Thank you both.

[st.bede]

Fyi… I am presently running out of the JHS Clover into the L aux. When I have the giggity I will run out of that into the R aux. (Assuming that the giggity is a real pre-amp, not a pedal that says pre-amp but is really just an od).

[nevershouldhavesoldit]

Fyi… I am presently running out of the JHS Clover into the L aux. When I have the giggity I will run out of that into the R aux. (Assuming that the giggity is a real pre-amp, not a pedal that says pre-amp but is really just an od).

I hope you’re not using only one speaker. Most class D amps need a load to prevent excessive voltage across the output filters. Even without an input signal on one channel, you could have oscillations that will damage the amp. Some have protective diodes on the output, but I strongly doubt that a $50 amp does.

Top quality products like Quilter and Henriksen have output protection, so you can use the headphone and line outputs without a speaker. But I strongly doubt that any of the $100 and under amps has this. I don’t know if the now discontinued Microblock has output protection, since the only output is a speaker jack. So I make sure there’s a speaker plugged in before I plug my Microblock in to a power outlet.

I once fried an amp because one conductor in a speaker wire broke at the plug. It was pretty dramatic!

[st.bede]

Thanks I did not know that.

[nevershouldhavesoldit]

Thanks I did not know that.

It’s also true for almost all tube amps. If you play through a tube amp with no speaker or equivalent load connected to the output, it will start to oscillate and take out the output tubes followed by the output transformer.

[st.bede]

I knew that one… I am paranoid about such things.

I did blow up a computer once. I was so used taking stuff out and putting stuff in, that I was not paying attention, and while putting in a new drive, I did not line up the connector correctly. Puff and gone.

I just thought home stereo would be different… why … not really sure… lack of thinking.

As always: Thank you.

[sgosnell]

I have a stereo amp, a Dayton Audio product, specs say it's Class D, that can be bridged, and can also drive two sets of speakers. Bridging is possible, just not often done, probably because there isn't much of a market for it.

[nevershouldhavesoldit]

I have a stereo amp, a Dayton Audio product, specs say it's Class D, that can be bridged, and can also drive two sets of speakers. Bridging is possible, just not often done, probably because there isn't much of a market for it.

Thanks! I've never seen a Dayton amp and don't know what power amp module they use. I just looked on their website and see that some of their amps are built to be bridged. The APA150 looks like a great solution for a 150W power amp if input sensitivities are right for preamp pedals (and, of course, if it sounds good). They describe some of their bridgeable amps as having discrete output transistors, so those output stages are designed for this and are more robust than the typical little chips in $50 amps.

There are two topologies for class D amps, and they're confusingly called half bridged and full bridged. This relates to the design of the amplifier circuit itself. Full bridged is a differential amp whose output voltage is generated between two hot leads and is independent of ground, similar to a balanced output in other amp classes. A half bridged circuit has a single output lead and the voltage is generated relative to ground (like an unbalanced output in other classes). I have to do some more reading to find out if / how this relates to the ability to bridge a stereo output to mono. Full bridged class D amps have twice the components of half bridged units, but they make more power from the same supply.

I also checked the entire ICE line (the gold standard for class D modules) and found that only 3 of their 30 or so models are bridgeable (125ASX2, 250ASX2, 80AM2).

[m_d]

For affordable class D amps I recommend you check Audiosciencereview.com for serious, professional, reliable reviews.
I have two class D amps they reviewed that are fantastic, if you don't need a ton of power - not just for the price, but you get true uncompromised high fidelity. They surpassed two brand-name amps that I had (Marantz and Teac). They are the Topping PA3s and the Loxjie A30. I run the Topping with a separate DAC and the A30 with a streamer. There are a few even cheaper alternatives with good measurements on ASR.