What Speakers Work best with the JLH 10W Class A Amplifier

[John Biles]

Hello Everyone,
I built the JLH 10W Class A Amplifier a while ago and with the speakers i was using, i was told that my Amplifier sounded broken and that the sound was too sharp and hurt their ears. When I changed over to my B Class Amplifier and played my B class through the same speakers, I was told "That sounds better".
My question is what speaker suits the JLH 10W amplifier.
As it was designed at a time when large paper cone speakers were the norm, should I be heading in that direction with my speaker choice?

[paulb]

A couple of comments:
What do they sound like to you? Maybe "they" are wrong.
And, maybe there is something wrong with the amplifier. It could be oscillating, or something else. It should sound good with pretty well any speaker system.
I built a prototype Class-A a while back and it sounded wrong, it turned out I had a bad connection to the capacitor in the feedback loop. Then it sounded great.

[John Biles]

Hello paulb,
In relation to your question that there may have been a fault with the JLH Amp i built, I just want to say that because the JLH 10W amp and the ESP 15W class A are so easy to make up in an hour or 2, I have built 3 JLH's and 2 ESP's on Tag Strip, Vero and finally an etched board and they sound fine to me, It didn't matter which way they were built, they still sounded the same. It's possible but unlikely that I made the same mistake every time. I liked the sound, but my relatives who visited said it sound too sharp like glass, that's why i asked if this Class A works better with a certain type of speaker (eg paper cone) that would sound better to the average listener than others.

[destroyer X]

Not kidding man, the best possible speaker, will be someone that will reach almost the end of the diafragm travel, when you connected the "under test" speaker to a DC supply pre adjusted to 8 volts.

It seems very obvious, but it is not.... talking serious.

regards,

Carlos

[DarkHorse]

Originally posted by paulb
built a prototype Class-A a while back and it sounded wrong, it turned out I had a bad connection to the capacitor in the feedback loop. Then it sounded great.

hi,paulb:
please post a simple schematics to express your amp's connection(feed back loop),thank you first!

regards!
WINCO

[Greg Erskine]

Originally posted by John Biles
It didn't matter which way they were built, they still sounded the same. It's possible but unlikely that I made the same mistake every time. I liked the sound, but my relatives who visited said it sound too sharp like glass, that's why i asked if this Class A works better with a certain type of speaker (eg paper cone) that would sound better to the average listener than others.

John,

Is the ESP amp the DoZ amp? My DoZ sounds good on any speakers I have tried it with but it doesn't play extremely loud as its only 10 or 15 watts.

Did you use the same power supply for all amps? If there is a common problem it might be there. What PSU are you using?

What output devices are you using?

What are you using for the output cap?

[John Biles]

Hello Greq Erskine,
I used a high ampage 28volt transformer and a 8amp bridge with about 8000uf of capacitors + 100n greencap on the power supply. The ESP amp was the Doz and I used the same transistors as listed in the Doz circuit diagram.
bc559, bd139 and 2n3055 transistors. The resistors were standard 5% and the same with all capacitors. On the output I tried from 1000uf to 6800uf electro's Caps as well as changing other cap values in the circuit. I just wanted to see how it sounded being a Class A and didn't want to spend a fortune on special Caps etc. With the Speakers I had at the time (Cheap Yamaha Bookcase 6.5inch woofer + tweeter) there wasn't a big enough differance for me to keep using the Doz over a Class B amp I had also built at the time and are still modifing as i could have more wattage without the heat. Now that I have brought some 3 way speakers, I will try the Class A again and see how it goes this time. I will built it from Scratch again and spend more time testing etc before i decide if i want to use it as my ever day amp

[Greg Erskine]

Hi John,

Sounds like you have given it a fair go. My DoZ is quite similiar but I do have 20,000uF filter caps and the PSU is CRC as recommended by Rod Elliott. I imagine it would make a little difference having less ripple.

I came to the same conclusion as yourself. I ended up staying with a class-AB amp because it sounded just a little better, had more power and no heat.

I can't remember if I have posted a picture of my DoZ so I'm sorry if I have.

[John Biles]

Hello Greq Erskine,
Nice Pic of your Doz Amp, I see you used a Elliot PCB, A lot nicer job than my amps, which were basically a copper PCB board with the layout drawn on it with a etching pen.

[MikeB]

Hmm, i've also built a DoZ, and the last thing i could say about it's
sounding is "broken" or "sharp like glass" !
I experienced a very warm/soft pleasant sound, the only reason i
rejected it was the enormous heat and the colorization.
I used MJL21194 as outputdevices, skipped the output-cap by using
a symetrical powersupply, and used a 2n5401 as input-bjt.
(I also added a small inputfilter, but should not make much difference)
The PSU was a very simple 500W,2x15v toroid, just a bridge-rectifier
and 2x22000uf. Biasing was ~1.5amperes.
I attached 3 different speakers, no problems !

Mike