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Rod Eliot project 88 question
Rod Eliot project 88 question
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Old 2nd March 2003, 12:55 PM   #11
supernet is offline supernet  Europe
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Me too!


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Old 2nd March 2003, 03:25 PM   #12
trwh is offline trwh  United Kingdom
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I've had about a dozen requests for the schematic of the remote control circuit since I made my original post. I always have to decline, since:

a) The circuit isn't mine, it is from a commercial product, albeit an old one.

b) Even if I did give you the schematic you would need the PIC, which is hard (if not impossible) to get hold of.

I don't know why there isn't a readily available remote control kit for motorised pots out there - if someone were to make one, I'm sure there would be a lot of interest.

See ya,
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Old 2nd March 2003, 03:27 PM   #13
trwh is offline trwh  United Kingdom
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Oh, and c) The PIC is programmed to work with Arcam handsets, which is why I chose the circuit in the first place.
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Old 2nd March 2003, 08:56 PM   #14
Mark25 is offline Mark25  United Kingdom
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here is a pre with different op amps and no cap's, it's from the AA bellini pre, which receives good press.


i built the one from the puccini (with caps) and was VERY pleased with the results with my p3a.
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Old 7th August 2003, 03:24 PM   #15
halojoy is offline halojoy  Sweden
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Default Re: Re: Rod Eliot project 88 question

Originally posted by halojoy

How about some information about what
ESP Project 88 is?

High Quality Audio Preamp (Mk II) - Rod Elliott (ESP)

It is a control preamp based on Burr-Brown OPA2134 dual OP.

Uses one OP for input and a second OP for output.
In between are Balance and Volume control.
It uses input and output caps.
You can select the gain of OPamp to suit your needs.
There are tables for how to Set the Gains of the OPamps.
Suggested Power Supply is 2x15VDC.
Preliminary measurments, on the workbench:

Frequency Response 10 Hz to 250 kHz -0.4 dB
Noise < 0.5 mV RMS at full gain (input open)
Crosstalk Better than -58 dB at 100 kHz
An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

Picture shows the Project 88; OPA2134 hifi pre amp
on the available PCB.

As rode - Rod Elliot has joined as one member by many at this site,
I'd like to say a welcome, afterwards.
The circumstances could have been better at his arrival.

The number of newbies, who has, through him, gotten a fair introduction
to the hobby of Audio Electronics, can be counted in 1000s
if not 100.000s.

There is often some stuff at his site we can refer and link to,
when somebody asks question, or want a circuit to build.
And so has halojoy done on many occations, for sure.

As I am not know for caressing ANY authority unnessesarely,
I say:
Welcome, but don't expect any other favours,
than ordinary members or Nelson Pass gets.
I will try to superwise that the moderators
keeps everything fair and square.

halojoy has one time said:
The higher you sit, the harder you hit
the ground at your fall

************************************************** ****************

In this thread we find a good example of what can be built
inspired by "Aussie-Rod":

"Project 88; OPA2134 hifi pre amp"

and in this thread with GREAT PICTURES

we see how it can combined with
"A double barrelled Elliott P3A Power Amp"

All these "great men" seems to be very busy
but I hope you can contribute every now and then, Rod.
Who would be more suited to comment on your projects?

halojoy - thinks rode's site is like "having circuits in the bank"
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Old 24th July 2018, 11:24 AM   #16
Mixi is offline Mixi  Europe
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let's bring this thread back to life. i know tons of people know the esp site and recommend reading the articles on it. yet i barely find any information on people building the projects. i read through project 88 and it seems like a fine preamp. yet the last entry in this thread is from 2003 - holy cow, that's 15 years ago.

what's the current opinion on this preamp design?
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Old 24th July 2018, 09:52 PM   #17
Mixi is offline Mixi  Europe
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guess it's not so popular. i wonder why. the design seems to be sound, low parts counts, well documented ....
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Old 24th July 2018, 11:00 PM   #18
jaycee is offline jaycee  United Kingdom
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Having built one myself many years ago I can say it performs extremely well
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Old 24th July 2018, 11:47 PM   #19
Dirttracker73 is offline Dirttracker73  United States
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Default P88

I have built two p88 preamps on strip-board. Very simple opamp implementation that sounds totally clear and provides volume and balance controls. I have tried several opamps including OPA2134, TL072, 4558, 4560, 4580, LM833, 2068, 5532, and MC33078. All except OPA2134 and TL072 have volume pot noise. Some are extremely noisey with low frequency (DC) effects and visible speaker cone excursion when turning the volume pot. Definitely needs a capacitor between the balance and volume pots if using bjt opamps. I can't hear any difference between OPA2134 abd TL072, both sound great. Just my $.02
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Old 25th July 2018, 12:53 AM   #20
jaycee is offline jaycee  United Kingdom
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Yep with BJT opamps there will be DC on the pot tracks and that will make it scratch
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