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Danelectro - N-10 Honeytone amp

PostPosted: 18 Mar 2010, 00:45
by markbr4769
Hello,

I have traced out circuit of the Danelectro Honeytone guitar amp.(attached). The preamp is a TL072. Can anyone help me understand what the main parts of the circuit are doing.
I know increasing R11 inceases gain. I checked the diodes too - initially thought they were soft clippers but they dont seem to be doing anything, there wasn't a difference when the were removed. Do you know what they are for then? Also,

1) what do: R2 and R9 do?

2) how is the tone control part working (ie R6, R7, C7, C8, C9, C11)?

Im pretty new to all this but im learning so i'll really appreciate it if someone could help explain it! Thank you.

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 01:14
by analogguru
The schematic is wrong:
R3 will be 5k6 (or R14 47k). R3 and R14 form a "bias divider" to obtain a voltage half of the power supply which is needed for proper operation.

This bias voltage is fed to the op-amp input via R2 and R9 - thats their function.

There are missing some components around the first op-amp - have a look again.

analogguru

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 03:05
by markbr4769
Analogguru,

Thank you for your reply, R4 is 47K not 4.7K as on the schematic. R3 is 56K. I've uploaded a corrected one. I've re-checked the components, they're no missing components. I've also duplicated this schematic onto a breadboard and it sounds fine. Now that R3 and R4 form the bias divider that halves the supply voltage, why are large R2 and R9 values needed before being fed to the non-inverting op-amp inputs? Im still unsure about the diodes though, as they dont cause clipping at all. In this circuit distortion is obtained only by turning the overdrive pot all the way up so that it hits the supply rails. Im wondering how i can add clipping at low volumes.

Danelectro - N-10 Honeytone amp

PostPosted: 18 Mar 2010, 03:06
by markbr4769
here's the corrected schematic
new honeytone circuit 2.JPG

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 03:11
by soulsonic
there MUST be something else connected to pin 6 of the TL072. I cannot see how it will function correctly without the proper connection to ground there. There should at least be a resistor connected between pin 6 and ground.

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 03:24
by markbr4769
:shock: Im sorry, i forgot to connect R5 and C5 to pin 6 when drawing the schematic. (I've been working on this circuit the whole day i've become careless!) I've reuploaded the schematic above :)

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 09:42
by soulsonic
Ah! Now it works! :D

Re: What are these parts doing?

PostPosted: 18 Mar 2010, 13:16
by G├╝ero 2.0

Re: Danelectro - Honeytone

PostPosted: 18 Mar 2010, 14:05
by Greg
Aren't the clipping diodes on a switch ?

Re: Danelectro - Honeytone

PostPosted: 18 Mar 2010, 18:33
by markbr4769
No, the diodes are not on a switch...and i as far as i know they dont cause clipping at all. When they're removed the sound stays the same. Clipping only occurs when the sound signal hits the supply rails. So im still wondering what these diodes are for. When the tone pot is turned all the way down, wouldn't the capacitors C7, 8, 9, 11 short thus the diodes could be there as some kind of protection mechanism? Im only guessing but could this be correct?

Re: Danelectro - Honeytone

PostPosted: 19 Mar 2010, 01:08
by Greg
markbr4769 wrote:No, the diodes are not on a switch...and i as far as i know they dont cause clipping at all. When they're removed the sound stays the same. Clipping only occurs when the sound signal hits the supply rails. So im still wondering what these diodes are for. When the tone pot is turned all the way down, wouldn't the capacitors C7, 8, 9, 11 short thus the diodes could be there as some kind of protection mechanism? Im only guessing but could this be correct?


The diodes run from the output of the 1st stage of the TL072 to ground, so they will certainly clip whenever the signal level is high enough.
I see now that they're controlled by the level of Drive from that stage rather than a switch.. so as you turn up the Overdrive knob they're brought into play, and you should definitely be able to hear their effect when Overdrive control is turned up.

Re: Danelectro - Honeytone

PostPosted: 21 Mar 2010, 15:43
by markbr4769
Greg_G wrote:The diodes run from the output of the 1st stage of the TL072 to ground, so they will certainly clip whenever the signal level is high enough.


I think you're right about the diode clipping. I checked it the output from pin 1 with an oscilloscope. The input was a 1Khz sine wave from the signal generator. The volume and overdrive pots were turned up only slightly about 20-25%. The oscilloscope readings are attached.

With two 1N4148 diodes --- peak-to-peak voltage is 2.88V
With two germanium diodes --- peak-to-peak voltage is 1.92V
With diodes removed --- peak-to-peak voltage is 5.72V

The diodes definitely reduce the voltage measured at pin 1. Am I right to say they cause clipping?
without diodes.bmp
with 1N4148 diodes 9v.bmp
with germanium 9v.bmp

Re: Danelectro - Honeytone

PostPosted: 12 Dec 2012, 11:04
by deegeedoil

Re: Danelectro - N-10 Honeytone amp  [schematic]

PostPosted: 08 Jun 2015, 03:19
by blackcorvo
Even tho this is a very old thread, I felt it would be better to continue it here rather than posting on a new one.

After taking a look at my own Honeytone and later confirming it with pictures of the PCB from http://batterypoweredguitaramp.com/dane ... amplifier/, I noticed the preamp's second op-amp resistors were wrong on the schematics posted on this thread. They were supposed to be 1k/2k2 instead of two 33k (you can see them on the pictures from that link, they're on the left side of the TL072, labeled 102 and 222).

I re-drew the schematic myself, but since I have no ways of measuring the SMD capacitor values to confirm if they are correct, I decided to keep the ones from the circuit posted before on this thread, as the tone control circuit itself is constructed the same way.

Here's the schematic:
Image

I personally like this amp a lot, and I'm considering making a "serious" version of it using a TDA7240 for the power amp. I already did try the circuit on a protoboard and the results were nice, and after that I made a layout but haven't built anything definitive yet.

Re: Danelectro - N-10 Honeytone amp

PostPosted: 14 Jul 2017, 16:36
by blackcorvo
The picture is down from the link I posted previously, but I still have it here:

Image

And just in case it goes down, I have it on my Google Drive as well:

https://drive.google.com/file/d/0B08phn ... sp=sharing

Re: Danelectro - N-10 Honeytone amp

PostPosted: 03 Dec 2017, 09:59
by mirosol
Drew this on a stripboard in case some might want to tweak it. I suspect it'll be a nice 1 watter, if one gives it a decent speaker cone and a wooden housing.

Re: Danelectro - N-10 Honeytone amp

PostPosted: 21 Jul 2018, 18:36
by Ichabod_Crane
It's still no verified :(