[BUILD] 1176 Rev A - Back to the beginning...

[sage]

I just noticed in the BOM there are 3.6k twice for R18 - it might be a good idea to change it, anyone else noticed?

sage

 

[evilcat]

Yep you're right.

 

[sage]

QUESTION:

I dont have a 1.1k 1Watt but i do have 1k and 1.2k both 1 watt - could i use them instead of the 1.1k ?

If so which one is better 1k or 1.2k ???

thank you

sage

 

[Harpo]

I dont have a 1.1k 1Watt but i do have 1k and 1.2k both 1 watt - could i use them instead of the 1.1k ?
If so which one is better 1k or 1.2k ???

Have a look at the formula, given at FI http://www.fairchildsemi.com/ds/LM/LM7805.pdf pg.23, fig.12.
From 1176 schematic you have 24V*(1+220R/1100R)+0.0052A*220R = 29.944V +/- parts tolerances = roundabout 30V.
If you substitute the 1100R with your 1000R in the formula above, you do the math to what value the 220R resistor needs to decrease for a similar result,
or if you substitute the 1100R with your 1200R in the formula above, you do the math to what value the 220R resistor needs to increase for a similar result.

 

[sage]

very clear - it seems i might as well get the right resistor if i got change others.....

 

[sage]

I see that in the BOM for 1.2.5 version there are no Volatges values for the Capacitors axcept for ones in the PS section.
Does that mean that I should get any kind? I am trying to select all Audio Grade Nichicons and Panasonics from Mouser but I sometime there are options 50V or 63V OR....


SUGGESTIONS?

sage

 

[Echo North]

I see that in the BOM for 1.2.5 version there are no Volatges values for the Capacitors axcept for ones in the PS section.
Does that mean that I should get any kind? I am trying to select all Audio Grade Nichicons and Panasonics from Mouser but I sometime there are options 50V or 63V OR....


SUGGESTIONS?

sage

Either would be fine.

 

[sage]

thank you - and for the FILM is WIMA 100Volts good or better Vishay Spraugue 600 Volts?

sorry so many questions... i didn't find a complete Mouser Cart/Bom so I am making my own...

 

[sage]

I have version 1.2.5 R44 shows 5k trimmer and the BOM a 1k var....

is the mistake in the BOM ?

I also pointed out that R18 appears twice in the BOM - could the powers at be perhaps fix these small mistake in the documentation?

MOST IMPORTANTLY FROM WHAT I READ IT IS A 5K TRIMMER FOR R44 - CORRECT?

THANK YOU

sage

 

[Echo North]

I have version 1.2.5 R44 shows 5k trimmer and the BOM a 1k var....

is the mistake in the BOM ?

I also pointed out that R18 appears twice in the BOM - could the powers at be perhaps fix these small mistake in the documentation?

MOST IMPORTANTLY FROM WHAT I READ IT IS A 5K TRIMMER FOR R44 - CORRECT?

THANK YOU

sage

R44 is the tracking adjust.  1K is probably fine, but 5K will give you a little more room to set the tracking.

 

[Echo North]

thank you - and for the FILM is WIMA 100Volts good or better Vishay Spraugue 600 Volts?

sorry so many questions... i didn't find a complete Mouser Cart/Bom so I am making my own...

It's really up to you.  If it's a cap in the audio chain, it's a sound quality thing which is complete dependent on what you prefer or even if you hear a difference .  600V is overkill in this circuit but that maybe all that is available (rather than say a 50V), so if it's available and is not too big then it's ok.  You can always go over on voltage rating depending on availability as long as size does not become an issue.

 

[sage]

Highly appreciated - by the way I am getting the enclosure and a few other things from you guys at Hairball - I started  a shopping cart but I need to understand what else I am missing before closing it....

sage

 

[oilcanstudios]

Hey everyone,

I searched through the threads and couldn't find an answer to this.


I just built a revision A and it sounds great it's really quiet, and is compressing.


It's not as aggressive as my g1176 though...

I tested the voltages on the pcb where they should be 30 they are currently 29.6 and where it should be -10 it's currently at -9.5v.

Everything seems to be working ok, it just seems like the threshold is engaging at the same point for all the ratios.


And the difference in compression is minimal between the ratios.

Any ideas? Hotter input signal? Bad fets?

 

[swimslowly]

Hi,

I just finished two of these and they sound excellent. The overall character is a bit "bright", but certainly not in a bad way. Compression quality is very nice and superior to most vintage units I've used.  A few "improvements" I might recommend to someone taking this project on:

External "Power One" power supply - absolutely no hum or PSU noise.

I used a Triad HS-54 input transformer wired in reverse (5K:150 ohms) which brings the input impedance into somewhat modern standards.

Added a 10K pot after the transformer (before the preamp input) so that level reduction could occur after the transformer if I want the peaks to saturate the transformer rather than the preamp stage.

I reduced the preamp feedback resistor R16 to 47.5K (from 100K) which made the levels on input more useable with lower noise (as is the preamp gain seemed very high).

Thanks to hairball/mnats for all the great work! A few pics (before I added the stereo link):

 

[evilcat]

Nice units, and HUGE transformer !!! Congrats.

Ben

 

[swimslowly]

Thank you! It was a bit more work than I expected (3 days for the two units), but worth it in the end.

Last night I was wondering why the units had a slightly bright tone so I ran a few different transformers in parallel to the  5002 600 ohm primary and the HF response improved substantially (less hyped) out of another output transformer (ADC from a 3M M56). I left the 5002 intact for it's tertiary windings/feedback - but was happy to find the transformer primary windings in parallel didn't diminish the sound quality at all.

 

[Echo North]

Wow!  Great work.  8)

 

[sage]

Hello there and happy veterans day -

I have a question probably typical of an uneducated in Electronics DIYourselfer like me...

ON our BOM for this built it states Q12 and Q13 Matched HFE - now just to be safe i did order a matched pair form Hariball but out of curiosity I did test the HFE of the 2N3707 that I have and they come out to be :

420 - 425 - 435 - 442 - 460 - 463 -

obviously the 460 and 463 are the closest - is this considered a MATCH or they have to be EXACT ? In other words is that a tolerance of percentage in Matching like there's tolerance in resistors' values or they have to be dead on matched?

As I said this is a curiosity but it is knowledge that can come handy....

Thank you

sage

 

[swimslowly]

I would just use the two closest in value. I doubt 3 HFE difference is going to change anything significant in the overall sound of the unit. Most of the ones I used were a few HFE off and the unit sounds great. 3 HFE difference at over 460 HFE is less than 1% tolerance, which seems excellent to me.

Just spent a few hours doing listening tests on the output transformers and decided the UTC's wired 600:250 on the output makes the compressor sound as it should. I went back and forth with the 5002 output, an ADC transformer, and then finally decided to test the UTC LS in the circuit and the UTC was a clear winner. The UTC's sound very natural with a nice extended LF presence. For whatever reason the 5002's sound like they have a built in HF boost. Does anyone know if these 5002's were wound by Cinemag? Anyways, just posting my results to encourage others to experiment with their transformer choices if the sound isn't quite right. Here's the final version with the stereo link and UTC's feeding the output:

 

[Echo North]

Does anyone know if these 5002's were wound by Cinemag?

No they are not.

Great stuff!