Tivoli Model ONE vs. KLH Model TWENTY ONE - Page 3 - diyAudio
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Old 7th February 2013, 05:46 PM   #21
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Hello tiefbassuebertr,
thank you for answering. For me it would not be neccessary to receive the original parts. I would also be happy with replacements. Of course the pins and the data have to be the same. Do you have a hint for an alternative variable capacitor and FET (U72)?
Wolfgang
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Old 6th April 2013, 12:27 AM   #22
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Did you ever get a schematic for the Tivoli Model One? I could use one because I am trying to fix one.

thanks - reply to deancesa@gmail.com
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Old 20th October 2013, 12:49 AM   #23
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Quote:
Originally Posted by deancesa View Post
Did you ever get a schematic for the Tivoli Model One? I could use one because I am trying to fix one.

thanks - reply to deancesa@gmail.com
Don't help the schemas by this URL ?
Harry's radio's: Tivoli PAL

Also nice for looking:
Crystal Radio Page
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Old 8th August 2014, 02:20 PM   #24
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Default Tone control modification for Tivoli Model One

Hi .. I have a Model One and whilst the sound is good, I find the level of bass is higher than it needs to be for general radio listening in the kitchen. I have blocked off the baffle on the base of the unit and this does help somewhat. I was wondering if anyone has tried to add a variable tone control to the Model One or to permanently reduce the level of bass. Ideally this would be done before the amplifier, however perhaps a simpler approach would be a fixed high pass crossover filter between amp and speaker. Has anyone tried this ? Does anyone have any suggestions for an appropriate circuit design ? Many thanks
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Old 9th August 2014, 05:26 PM   #25
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Originally Posted by AlisterSimington View Post
Hi .. I have a Model One and whilst the sound is good, I find the level of bass is higher than it needs to be for general radio listening in the kitchen. I have blocked off the baffle on the base of the unit and this does help somewhat. I was wondering if anyone has tried to add a variable tone control to the Model One or to permanently reduce the level of bass. Ideally this would be done before the amplifier, however perhaps a simpler approach would be a fixed high pass crossover filter between amp and speaker. Has anyone tried this ? Does anyone have any suggestions for an appropriate circuit design ? Many thanks
adding a nonpolar capacitor, or reducing the value of an existing one, anywhere in the audio signal path, will probably get you a decent result.
the value depends on the impedance of the circuit at the point where you add/alter it and the frequency where you want the rolloff to begin.
using the PAL schematic as an example, you could change C1 from 100nf to 50nf or less or you could change C7 from 220nf to 100nf or less.
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Last edited by sfthurber; 9th August 2014 at 05:34 PM.
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Old 9th August 2014, 05:40 PM   #26
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We had exact the same problem.
After some investigations I can say I have it fixed now -
at least according to the taste of my wife an me.
Give me a bit time, I have to look for some documentation.

I am sorry to say that I did not document my patches.
From my recollection I did the following

Dismantle Tivoli Radio - inside the "high end" you will find a mess of cheap far-East stuff that looks like transistor radios pcbs of the seventies.

There is a quad operational amp inside, a chip with 14pin.
Audio signal internally is stereo, i.e. half chip/channel.

Apply some 1khz square signal to aux input.

Check the corner pins of the IC with an oscilloscope - each corner pin is an opa output.
You will find two outputs with significant overshoot - this indicates audible treble boost.
Connect both inputs via 1k resistor resulting in a mono output.
Route this mono output to the input of power Amp (TDA....) via a coupling cap.
The smaller the value, the less bass will be produced.
I forgot the value I inserted, but 100nF foil cap may be a starting value.
Before doing that you have to disconnect the existing input coupling cap of TDA....from existing signal path.





Apply 1khz square signal to aux input.

Last edited by voltwide; 9th August 2014 at 05:59 PM.
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Old 9th August 2014, 07:14 PM   #27
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you could, alternatively, add a nonpolar cap in series with either speaker lead but that has the disadvantage of requiring a relatively big cap -- maybe 1000uf, more or less according to taste.
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Old 10th August 2014, 07:42 AM   #28
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Thank you all very much for your replies. The capacitor before the speaker looks simplest ... and I may go this was I do not have an oscilloscope handy. However Voltwide ... can you advise why you suggested making the internal mono ? i.e. would it be simpler to keep stereo and just change out two capacitors instead ... one for each channel ? As suggested by Steve I could look for the equivalent of C7 in the PAL circuit at Harry's radio's: Tivoli PAL and change this for each channel ?

Also it looks as if Tivoli boost the bass level somehow perhaps in this stage. Looking at the PAL circuit, could a POT be used instead to make the roll off frequency somewhat variable ? This could be made accessible via rear panel.

Thanks Alister
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Old 10th August 2014, 08:11 AM   #29
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I wired it mono to connect both channels to the single speaker
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Old 24th August 2014, 02:17 AM   #30
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Hi, how can I make it stereo so that I can connect it to external speaker. I have a pair of fostex 3" full range speaker(forgot the model no.) in a bass reflex enclosure.

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