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JamJar: an HPA-1-inspired power amp
JamJar: an HPA-1-inspired power amp
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Old 23rd November 2019, 02:50 PM   #21
EUVL is offline EUVL  Europe
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Because there are many others who also use the same as me.


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Old 23rd November 2019, 03:02 PM   #22
Mark Johnson is offline Mark Johnson  United States
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JamJar: an HPA-1-inspired power amp
Observe this black magic: Here's a link to post #89 that works equally well for people who view 10 posts/page, and for people who view 50 posts/page

voila -- here is post 89

Tried it just now in Opera, Chrome, Internet Explorer, and Firefox. Turkey Worky all four times.


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Old 23rd November 2019, 03:27 PM   #23
Markw4 is online now Markw4  United States
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Very interesting. I looked at the difference in the links, looks like the working one is more of an absolute url and the default link is more of a relative url?
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Old 23rd November 2019, 04:49 PM   #24
jam is offline jam  United States
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Itsmee,

Your current mirror of choice is a cascode current mirror. It has a problem in the it reduces the maximum output voltage swing. It is best used in pre-amp circuits where you signal is not required to swing close to the rails.

The way around this is a folded cascode current mirror..........but the complexity?


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Last edited by jam; 23rd November 2019 at 05:01 PM.
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Old 23rd November 2019, 05:02 PM   #25
Itsmee is offline Itsmee  England
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JamJar: an HPA-1-inspired power amp
Thank you Jam, I can get slightly more than 28V peak from +-36V supplies, enough for the Little Pucker on +-24V supplies, not that it matters, 5V rms into my speakers is uncomfortably loud

Apologies Jeff for the unintentional hijack.

Last edited by Itsmee; 23rd November 2019 at 05:10 PM.
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Old 23rd November 2019, 07:05 PM   #26
jam is offline jam  United States
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Default Hijack?

Itsme,

I think (hope) Jeff looks upon this thread as a forum to explore ideas for his amplifier and I would think any exchange of ideas would be fine. I am curious to see what topology he picks for the JamJar.

Apart from the Sony topology the one attached has some possibilities. I would look at the use of current sources and improved mirrors. It is based on Hitachi app. notes for their mosfet's and was used by Goldmund and Perraux. I think the orignal desing belongs to Tektronix or HP for use in scope front ends.

It can be marginally unstable if not correctly compensated but when optimized can sound excellent......low distortion......wide bandwidth.......and excellent slewing characteristics.
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Last edited by jam; 23rd November 2019 at 07:12 PM.
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Old 23rd November 2019, 07:12 PM   #27
2 picoDumbs is offline 2 picoDumbs  Australia
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Mr JamJar

That is a bloody nice circuit.
Built that one up many years ago biased into Class A.
Highly Recommend it.

I used Jfets at front end and reduced open loop gain on a second version of the circuit.
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Old 23rd November 2019, 07:16 PM   #28
2 picoDumbs is offline 2 picoDumbs  Australia
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Jam, hope you don't mind being called JamJar.

In Australia we like to give people nick names, we almost never use peoples real names.
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Old 23rd November 2019, 07:17 PM   #29
jam is offline jam  United States
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Hi Pico,

No worries.......an amplifier named after me......

I wonder if down under we might have to modify the name............

Jam
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Last edited by jam; 23rd November 2019 at 07:19 PM.
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Old 23rd November 2019, 07:22 PM   #30
2 picoDumbs is offline 2 picoDumbs  Australia
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Hahahahaha

The richest natural source of Vitamin B.
It's the greatest thing on toast.
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