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 Forum index » DIY Hardware and Software » Jürgen Haible designs
Dim D
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What "chipset" would you like to see in a Dim D PCB
Original chips. They are still out there.
76%
 76%  [ 39 ]
Low voltage BBDs - easier to get, probably more noisy. Takes longer to design.
5%
 5%  [ 3 ]
Make a PCB that allows both options. Will be more expensive (more PCB area required!), and will take the longest to design.
13%
 13%  [ 7 ]
Not interested. (Who needs a Dim D? And isn't there another Dim D project on the way?!)
3%
 3%  [ 2 ]
Total Votes : 51

Author Message
living sounds



Joined: Mar 27, 2009
Posts: 9
Location: Germany

PostPosted: Fri Mar 27, 2009 7:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi everybody,

first I'd like to say thanks to Jürgen for this great project!

So I finished my Dimension D (modern component version) yesterday and it generally works as it should.

But I've got a few remaining question:

1. Compared to the examples provided on your website my build seems to lack some clarity in the high end. I've taken great care to use quality components (Elna Silimic II electrolytics, WIMA polypropylene whereever possible, otherwise MKP, NPO ceramics wherever possible). The frequency response is quite uneven, here is an mp3 of a sine sweep (mode 4):

www.scherer.de/Download/DimDSweep.mp3

2. Is the unit set up for +4db operation? It does seem to distort (on program material) with the bias set to optimal settings at these levels. Works fine at -10db (but THD in general still is quite high, as can be seen on the mp3).

The power supply seems to be able to handle it, at +4db the noise is at -92db, and there isn't any hum to speak of. All opamps get fed almost perfect +- 15V .

3. I've got a slight deviation between left and right channel, maybe 1/2 db. I replaced C67 with a 100uf one for now because the 47uf one blew up (due to wrong orientation), can this be the cause? Could anything have been damaged due to the cap failure?

4. The trimpots near the MN3007s don't seem to do anything.

5. Same goes for all the trimpots on the main board. Is this correct?

6. What would happen if one actually used shorting unbalanced connections?

7. Finally: Can I put in 5532/5534 op amps instead of the TL071/2 here? I've got some vintage ones that sounded great in every other unit I used them.

Thanks in advance!
Gregor
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Fri Mar 27, 2009 8:16 am    Post subject: Reply with quote  Mark this post and the followings unread

living sounds wrote:

3. I've got a slight deviation between left and right channel, maybe 1/2 db.


Oh, this is analogue electronics, not measurement equipment!
Can you actually hear 0.5dB ?!

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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living sounds



Joined: Mar 27, 2009
Posts: 9
Location: Germany

PostPosted: Fri Mar 27, 2009 8:18 am    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
living sounds wrote:

3. I've got a slight deviation between left and right channel, maybe 1/2 db.


Oh, this is analogue electronics, not measurement equipment!
Can you actually hear 0.5dB ?!

JH.


I'm not really bothered about that anyway. Smile But the other questions give me some trouble, especially the distortion and the frequency response. Is this how it should be in my unit?
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jhaible



Joined: May 25, 2007
Posts: 2014
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Audio files: 24

PostPosted: Fri Mar 27, 2009 8:24 am    Post subject: Reply with quote  Mark this post and the followings unread

living sounds wrote:
jhaible wrote:
living sounds wrote:

3. I've got a slight deviation between left and right channel, maybe 1/2 db.


Oh, this is analogue electronics, not measurement equipment!
Can you actually hear 0.5dB ?!

JH.


I'm not really bothered about that anyway. Smile But the other questions give me some trouble, especially the distortion and the frequency response. Is this how it should be in my unit?


Hart to tell. Do you notice any unpleasant distortion (other than the "warming" of the sound) on vocals for instance?

BBDs *do* add distortion. That's why these old boxes are so sought after - they give a warmness that's hard to achieve otherwise.

About using different opamps: You can try othe rones, but wathch for offset voltages and HF oscillations.
Generally, I think the THD is dominated by the BBDs and the compander chips in this circuit, though.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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living sounds



Joined: Mar 27, 2009
Posts: 9
Location: Germany

PostPosted: Fri Mar 27, 2009 10:18 am    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
living sounds wrote:
jhaible wrote:
living sounds wrote:

3. I've got a slight deviation between left and right channel, maybe 1/2 db.


Oh, this is analogue electronics, not measurement equipment!
Can you actually hear 0.5dB ?!

JH.


I'm not really bothered about that anyway. Smile But the other questions give me some trouble, especially the distortion and the frequency response. Is this how it should be in my unit?


Hart to tell. Do you notice any unpleasant distortion (other than the "warming" of the sound) on vocals for instance?

BBDs *do* add distortion. That's why these old boxes are so sought after - they give a warmness that's hard to achieve otherwise.

About using different opamps: You can try othe rones, but wathch for offset voltages and HF oscillations.
Generally, I think the THD is dominated by the BBDs and the compander chips in this circuit, though.

JH.


Thanks! The THD seems to be quite high, did you have a look at the mp3? Below 100 Hz distortion is as high as 35 db below the wanted signal, around 8khz it is ca. 50 hz lower.
So what about the frequency response? Is this normal (because your examples don't seem to show this behavior. Any hints on what could be the culprit for this?

Thanks!
Gregor
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jhaible



Joined: May 25, 2007
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Audio files: 24

PostPosted: Fri Mar 27, 2009 11:38 am    Post subject: Reply with quote  Mark this post and the followings unread

living sounds wrote:
jhaible wrote:
living sounds wrote:
jhaible wrote:
living sounds wrote:

3. I've got a slight deviation between left and right channel, maybe 1/2 db.


Oh, this is analogue electronics, not measurement equipment!
Can you actually hear 0.5dB ?!

JH.


I'm not really bothered about that anyway. Smile But the other questions give me some trouble, especially the distortion and the frequency response. Is this how it should be in my unit?


Hart to tell. Do you notice any unpleasant distortion (other than the "warming" of the sound) on vocals for instance?

BBDs *do* add distortion. That's why these old boxes are so sought after - they give a warmness that's hard to achieve otherwise.

About using different opamps: You can try othe rones, but wathch for offset voltages and HF oscillations.
Generally, I think the THD is dominated by the BBDs and the compander chips in this circuit, though.

JH.


Thanks! The THD seems to be quite high, did you have a look at the mp3? Below 100 Hz distortion is as high as 35 db below the wanted signal, around 8khz it is ca. 50 hz lower.
So what about the frequency response? Is this normal (because your examples don't seem to show this behavior. Any hints on what could be the culprit for this?

Thanks!
Gregor


I haven't made any frequency response measurements.
Expect a little bit of HF rolloff, but nothing dramatic.
I haven't visually analyzed your mp3, I'm sorry.
Spent the whole day shipping Solina boards.
If you have too much loss on the high end, check the capacitor values in the opamp feedback path - that's the first thing I'd do.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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jhaible



Joined: May 25, 2007
Posts: 2014
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Audio files: 24

PostPosted: Fri Mar 27, 2009 11:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Oh, increasing THD towards the bass range is typical NE570 compander behaviour. *Good* for the sound, IMO!

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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living sounds



Joined: Mar 27, 2009
Posts: 9
Location: Germany

PostPosted: Fri Mar 27, 2009 11:54 am    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
Oh, increasing THD towards the bass range is typical NE570 compander behaviour. *Good* for the sound, IMO!

JH.


OK, no problem there then! Smile

There's a frequency plot of a 20Hz-20Khz linear sine sweep through the unit (mode 4) attached to this post. Impedances on my converter (balanced connection) are 24 ohms on the input and 100 ohms on the output.

The low end as well as the high end are 9 db down compared to the parts in the midrange with the highest amplitude. This seems too much to me.

BTW, is the chorus made for +4 db level input?

Thanks for your time, it's great to get answers here so quickly!

Gregor


Sweep.JPG
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jhaible



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PostPosted: Fri Mar 27, 2009 3:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

living sounds wrote:

BTW, is the chorus made for +4 db level input?


Yes, the service manual says so.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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living sounds



Joined: Mar 27, 2009
Posts: 9
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PostPosted: Sat Mar 28, 2009 7:32 am    Post subject: Reply with quote  Mark this post and the followings unread

I've just checked the individual pathways. The input stage of the main board is fine. But the return signal from the BBD board is severly bandlimited, the signal falls steeply above 9,5 khz as well as below 70Hz (the latter one doesn't matter much in a real world application). Could this be caused by one of the ceramic opamp feedback caps having the wrong value? The problem is that a lot of them are unlabled (though I took care - I thought - to put them in correctly)...
Or could this be caused by a broken transistor?


Thanks!
Gregor
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jhaible



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PostPosted: Sat Mar 28, 2009 8:23 am    Post subject: Reply with quote  Mark this post and the followings unread

living sounds wrote:
I've just checked the individual pathways. The input stage of the main board is fine. But the return signal from the BBD board is severly bandlimited, the signal falls steeply above 9,5 khz as well as below 70Hz (the latter one doesn't matter much in a real world application).


Band limiting the BBD signal is intentional. 10kHz seems about right.
I wouldn't call it "severe" - it's just the BBD path, and not the overall response, after all.
All in all, it means the highest frequencies are there - just a little attenuated, and not "chorussing".

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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living sounds



Joined: Mar 27, 2009
Posts: 9
Location: Germany

PostPosted: Sun Mar 29, 2009 11:54 am    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:

Band limiting the BBD signal is intentional. 10kHz seems about right.
I wouldn't call it "severe" - it's just the BBD path, and not the overall response, after all.
All in all, it means the highest frequencies are there - just a little attenuated, and not "chorussing".

JH.


That's all right then!

The distortion is still there though. Even at lower levels the audio distorts audibly on exposed midrange heavy material like vocals and piano.
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ognam



Joined: May 04, 2009
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Location: Berlin

PostPosted: Mon May 04, 2009 9:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello Everybody...
I have one question:

Is this transformer too small for the PSU of a Dim D version (2 PCBs)?

http://www.reichelt.de/?;ACTION=3;LA=2;GROUP=C526;GROUPID=3317;ARTICLE=27380;START=0;SORT=artnr;OFFSET=50;SID=25zxgdgqwQARkAACD9s@U39ebd88fa2d8386219f8fca69d8c7db0

or should that be a toroid to avoid hum?

Thanx Jonas
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jhaible



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PostPosted: Mon May 04, 2009 10:20 am    Post subject: Reply with quote  Mark this post and the followings unread

ognam wrote:
Hello Everybody...
I have one question:

Is this transformer too small for the PSU of a Dim D version (2 PCBs)?

http://www.reichelt.de/?;ACTION=3;LA=2;GROUP=C526;GROUPID=3317;ARTICLE=27380;START=0;SORT=artnr;OFFSET=50;SID=25zxgdgqwQARkAACD9s@U39ebd88fa2d8386219f8fca69d8c7db0

or should that be a toroid to avoid hum?

Thanx Jonas


These things are crap, IMO. Huge stray field, and no mounting screws.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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ognam



Joined: May 04, 2009
Posts: 7
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PostPosted: Tue May 05, 2009 12:52 am    Post subject: Reply with quote  Mark this post and the followings unread

OK... Thanks.
Then I will go for a toroid. How much mA will I need for each winding for my Dim D version?

I also have another question...
What is meant with "no floating balanced outputs"?
Can I connect the outputs to an unballanced input if I take a Cable where Pin3 of the XLRs is left out so that it is not shorted to ground?

Is there any problem to connect an unballanced input to the XLR ins?

Thank you for this great project!

Jonas
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jhaible



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PostPosted: Tue May 05, 2009 11:21 am    Post subject: Reply with quote  Mark this post and the followings unread

ognam wrote:
OK... Thanks.
Then I will go for a toroid. How much mA will I need for each winding for my Dim D version?


This depends on so many things that I'm reluctant to give numbers here.
But the smallest non-PCB-mount toroidals from Reichelt are 30Watt, and that is *plenty*. (My prototype is powered with a 12 Watt wallwart.)

Quote:
What is meant with "no floating balanced outputs"?
Can I connect the outputs to an unballanced input if I take a Cable where Pin3 of the XLRs is left out so that it is not shorted to ground?


Yes - emphasis added.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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lexvortex



Joined: May 14, 2008
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PostPosted: Tue May 12, 2009 9:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi JH,

I have a question about the BC550C, can I use a BC550B instead? Also can I use a LM13700 instead of the LM13600?

Thanks Very Happy ,
Dave
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jhaible



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PostPosted: Tue May 12, 2009 10:53 am    Post subject: Reply with quote  Mark this post and the followings unread

lexvortex wrote:
Hi JH,

I have a question about the BC550C, can I use a BC550B instead? Also can I use a LM13700 instead of the LM13600?

Thanks Very Happy ,
Dave


Yes, and yes.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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lexvortex



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PostPosted: Wed May 13, 2009 1:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi JH,

Quote:
lexvortex wrote:
Hi JH,

I have a question about the BC550C, can I use a BC550B instead? Also can I use a LM13700 instead of the LM13600?

Thanks Very Happy ,
Dave


Yes, and yes.


Thanks Very Happy ,
Dave
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lexvortex



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PostPosted: Mon May 18, 2009 11:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi JH,

I have another question about components. For the BC560, what is the best replacement for that? BC557? I've built quite a few projects that specify BC560s and allow a replacement using a BC557, I am curious as to why the BC560 is chosen rather than the BC557 or other equivalents and what difference it makes to the circuit. I have heard that the BC560 is a "quieter" or low noise version of the others. Would it be worth my time to track down the BC560 and replace the BC557s with them eventually.

Thanks,
Dave
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JoeMorris



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PostPosted: Mon May 18, 2009 12:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Is the N570N OK for this project?
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jhaible



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PostPosted: Mon May 18, 2009 2:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

JoeMorris wrote:
Is the N570N OK for this project?


You mean NE570N ?

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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JoeMorris



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PostPosted: Mon May 18, 2009 2:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

yes, sorry..!
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jhaible



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PostPosted: Tue May 19, 2009 12:02 am    Post subject: Reply with quote  Mark this post and the followings unread

JoeMorris wrote:
yes, sorry..!


Yes, NE570N is good.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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JoeMorris



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PostPosted: Tue May 19, 2009 12:55 am    Post subject: Reply with quote  Mark this post and the followings unread

ive just realised ive been rather silly and that NE570N is on the PCB silk screen and BOM. I was just going on the first page of this thread. doh! thanks anyway.
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