EQN build thread

[Marcocet]

Not quite:

They're working perfectly on my bench with the bench power supply and with a +/-15v wall wart I've got. However when I take them to the studio and plug them in to either the rack or the desk they pass almost no signal (like 30 some db down). This happens in both the 500 series rack (Purple Sweet 10) and in the desk. My other EQN modules work perfectly in both the desk and rack.

Really confusing one.... but that's how they go. Thanks for the help Peter! Anybody else have any ideas?

EDIT Solved, I'm an idiot. Neutral side of transformer secondaries were reversed. Signal was canceling itself out I checked that first but missed it somehow...

 

[number2]

First of all, I take issue with your discriminatory policy against idiots.

2nd, will this work for c25?

http://www.mouser.com/Search/ProductDetail.aspx?R=MKS4D024702A00KSSDvirtualkey50520000virtualkey505-MKS4.047%2f100%2f10

 

[peter purpose]

Sorry, I haven't been keeping an eye on this thread.
It'll work if the leads are long enough. As in the bom... you want a 10mm/0.4" lead spacing.

My policy stands and will be strictly enforced.

 

[number2]

well I'm related to some idiots and they're really nice people ;D

thanks bud

 

[number2]

http://au.mouser.com/ProductDetail/Diodes-Inc-Zetex/ZTX796A/?qs=%2f4dsY8i%2fUxIDKYU0UcTJ%2fFdTORtTHkvDu%252bKvCRzUrZk%3d

will this replace the bc184c that is obsolete?

I have a relative who is an idiot that wants to know

 

[peter purpose]

will this replace the bc184c that is obsolete?

No idea, but try bc550c.

 

[number2]

anyone care to teach a lesson on transistor replacement?

I read that these are the important values to compare when substituting transistors. Any comments would be appreciated.
Does this table let me know that the bc550c is a good substitute for the bc184c? I trust that it is I just want to know why

 

[number2]

I'm not passing audio. what do I check first?

 

[peter purpose]

I'm not passing audio. what do I check first?

Your signal generator.

 

[number2]

signal generator? I'm just plugging a mic into the lunchbox w/ EQN

audio goes in via the mic but doesn't come out

are there known multimeter voltage measurements I can check to find the problem?

 

[benlindell]

There's your first problem right there. You need to connect a line level source to the EQN to test it, it's not a mic preamp.

signal generator? I'm just plugging a mic into the lunchbox w/ EQN

audio goes in via the mic but doesn't come out

are there known multimeter voltage measurements I can check to find the problem?

 

[number2]

Oh thanks bud

I had it going thru a preamp 1st but I guess not line level. I used the HiZ input and now it is working

 

[jrowell]

Hello All,

This might be of interest to any builders of this kit.

I don't know if this has been addressed in a board revision, I did not find mention of it in the thread.

The board versions I have just completed for a client had a missing connection in the LF switch/BA205 card area. 

The symptom is LF response shelved below about 500 Hz, -1.8dB down, or so, with EQ in and all bands set to off.

If you are doing just mid or top EQ, this is a problem.

If the LF band is set to off, the response droops below 500Hz.

Since I am a vintage N*v-e service technician, I knew the issue would be in the off paths of the LF freq switch.

The offs go to one side of C29, a 10nF. The other end of C29 feeds the BA205 cap buss.

The pot wiper goes to one end of R10, a 12K. The other end of the 12K goes to C30 and to the LO/HI amp input.

The pot wiper is normally permanently connected to the off positions. It is not here.

The offs end of C29 and the wiper end of R10 are also normally connected together. Again, not here. This is pin L on an original BA205 board diagram.

Basically we have two pin L points. They need to be connected.

All this can be resolved by connecting the offs end of C29, (side nearest the switch) and the wiper end of R10, (the end closest to the inductor) together with a jumper wire.

Boom, no droop in LF with EQ in and LF set to off.

LF EQ at full cut or boost stays basically identical. Curve is maybe a tad more relaxed.

They actually are a bit flatter than an original, with this corrected.

There are some other details that we found, that improve things, but very excellent execution overall.

This one is a biggie, and I wanted to give something back to DIY. It has been good to me.

We have made a reputation of taking DIY based stuff and turning it into custom level builds, with excellent performance, and all inherent issues solved. 

The EQ is most impressive with the reasonably small number of inherent issues solved.

Thanks again, I hope this helps someone out.

James Rowell
Audio Systems Technician
Sound Service Electronics
www.ssevintageaudio.com

Ask about our 1176 Rev B w/ factory LN build.

 

[canidoit]

Let me get this straight.

- If you put the EQ in and the Lo Freq set to off, there is a low frequency loss to the signal, even without doing any changes to the other knobs? Does this mean it changes how the curves react when adjusting the other frequencies?
- If you only use the mid and high end part of the eq, means users will encounter this issue? How about if you just leave the low shelf to "on" but the gain at 0, will there still be a problem?
- Can you please provide images and a diagram of the fix you describe?
- If you create a wire link that you mention, this will solve the problem?
- Applying this fix, does that mean you have to re-calibrate the unit again?
- Are there any other issues with this unit and if so, what is the fix?

Thanks

Hello All,

This might be of interest to any builders of this kit.

I don't know if this has been addressed in a board revision, I did not find mention of it in the thread.

The board versions I have just completed for a client had a missing connection in the LF switch/BA205 card area. 

The symptom is LF response shelved below about 500 Hz, -1.8dB down, or so, with EQ in and all bands set to off.

If you are doing just mid or top EQ, this is a problem.

If the LF band is set to off, the response droops below 500Hz.

Since I am a vintage N*v-e service technician, I knew the issue would be in the off paths of the LF freq switch.

The offs go to one side of C29, a 10nF. The other end of C29 feeds the BA205 cap buss.

The pot wiper goes to one end of R10, a 12K. The other end of the 12K goes to C30 and to the LO/HI amp input.

The pot wiper is normally permanently connected to the off positions. It is not here.

The offs end of C29 and the wiper end of R10 are also normally connected together. Again, not here. This is pin L on an original BA205 board diagram.

Basically we have two pin L points. They need to be connected.

All this can be resolved by connecting the offs end of C29, (side nearest the switch) and the wiper end of R10, (the end closest to the inductor) together with a jumper wire.

Boom, no droop in LF with EQ in and LF set to off.

LF EQ at full cut or boost stays basically identical. Curve is maybe a tad more relaxed.

They actually are a bit flatter than an original, with this corrected.

There are some other details that we found, that improve things, but very excellent execution overall.

This one is a biggie, and I wanted to give something back to DIY. It has been good to me.

We have made a reputation of taking DIY based stuff and turning it into custom level builds, with excellent performance, and all inherent issues solved. 

The EQ is most impressive with the reasonably small number of inherent issues solved.

Thanks again, I hope this helps someone out.

James Rowell
Audio Systems Technician
Sound Service Electronics
www.ssevintageaudio.com

Ask about our 1176 Rev B w/ factory LN build.

 

[jrowell]

Okay,

Yes. Yes.
Yes. Yes.

If you put the EQ in, and all switches to OFF, and do a freq sweep plot you should see it very obviously.

Original N* modules have a bit of passband ripple (more like a very gradual wave) with the EQ in, but not nearly that much, maybe 0.5dB. It depends on how much is wrong with the module. There is something wrong with almost all of them.

Tracing out the points from the description I have provided will take you about 2 min, it will take me 20 to snap and photoshop pics and post them. The points are quite easy to find, the LF pot wiper only goes to the correct end of the 12K R10. The correct end of C29 is the only thing attached to one of the LF switch points.

Yes, one wire link solves the issue. Unfortunately you will not be able to do it from the top of the board.

Make sure this hasn't been caught in a board rev. Measure the points first. They should be 0 ohm. Power OFF. Not any other than 0 ohm. If not do the link.

You should have calibrated in bypass, so if so no.

There are some other items of interest, I think that my client that paid a premium for me do do these my way might be annoyed if I give away much more.

This was a big one, that really affects the performance of the unit, so I don't mind sharing it. Besides, it is a missing connection on this project, not a N* thing that can be applied to other modules that I service.

The others are N*v-e tidbit stuff that I do hold close.

Just one, most all Neve Class A modules, and all clones I am aware of are biased wrong.

That is the most critical setting ever in history in terms of the effect on tone, and it is the main reason people complain of 'pointy N*v-e'

I never got that 'pointy N*v-e' thing until I started getting in more working modules that had been set wrong, over the last number of years, it is a big issue.

That is a service I offer, to original modules. Clones usually need modding to bias correctly, so unless the extra work is discussed and understood, I wouldn't be doing those.

I do need to cover my time with billable work, and I do have to respect my clients needs with current ongoing projects, so I must return to soldering and the AP.

Thanks guys,

James

Let me get this straight.

- If you put the EQ in and the Lo Freq set to off, there is a low frequency loss to the signal, even without doing any changes to the other knobs? Does this mean it changes how the curves react when adjusting the other frequencies?
- If you only use the mid and high end part of the eq, means users will encounter this issue? How about if you just leave the low shelf to "on" but the gain at 0, will there still be a problem?
- Can you please provide images and a diagram of the fix you describe?
- If you create a wire link that you mention, this will solve the problem?
- Applying this fix, does that mean you have to re-calibrate the unit again?
- Are there any other issues with this unit and if so, what is the fix?

Thanks

Hello All,

This might be of interest to any builders of this kit.

I don't know if this has been addressed in a board revision, I did not find mention of it in the thread.

The board versions I have just completed for a client had a missing connection in the LF switch/BA205 card area. 

The symptom is LF response shelved below about 500 Hz, -1.8dB down, or so, with EQ in and all bands set to off.

If you are doing just mid or top EQ, this is a problem.

If the LF band is set to off, the response droops below 500Hz.

Since I am a vintage N*v-e service technician, I knew the issue would be in the off paths of the LF freq switch.

The offs go to one side of C29, a 10nF. The other end of C29 feeds the BA205 cap buss.

The pot wiper goes to one end of R10, a 12K. The other end of the 12K goes to C30 and to the LO/HI amp input.

The pot wiper is normally permanently connected to the off positions. It is not here.

The offs end of C29 and the wiper end of R10 are also normally connected together. Again, not here. This is pin L on an original BA205 board diagram.

Basically we have two pin L points. They need to be connected.

All this can be resolved by connecting the offs end of C29, (side nearest the switch) and the wiper end of R10, (the end closest to the inductor) together with a jumper wire.

Boom, no droop in LF with EQ in and LF set to off.

LF EQ at full cut or boost stays basically identical. Curve is maybe a tad more relaxed.

They actually are a bit flatter than an original, with this corrected.

There are some other details that we found, that improve things, but very excellent execution overall.

This one is a biggie, and I wanted to give something back to DIY. It has been good to me.

We have made a reputation of taking DIY based stuff and turning it into custom level builds, with excellent performance, and all inherent issues solved. 

The EQ is most impressive with the reasonably small number of inherent issues solved.

Thanks again, I hope this helps someone out.

James Rowell
Audio Systems Technician
Sound Service Electronics
www.ssevintageaudio.com

Ask about our 1176 Rev B w/ factory LN build.

 

[Marcocet]

Interesting. I hadn't noticed it but I'm going to take a closer look now. Thanks for the tip!

 

[jensenmann]

James, thanks a lot for your hint.

 

[peter purpose]

James,
Thanks for pointing that out.

canidoit... leave the man alone.... he has said he's busy.
No revisions address anything but transformer connections.

None of us noticed anything lacking, so make your own mind up about pulling your modules apart.

 

[jrowell]

Hey no prob guys, I looked for a board version number, but couldn't find one.... It sounds like Peter has said the only revs involved TX stuff...

I know these are early ones, this was a closet project as the client did other things first.

As far as subjective, it is a big difference, so I would do it, personally. Everything can be taken as subjective, since it all affects tone. Correct is different. This is a subjective tone change caused by an incorrect wiring. That would be something other than subjective.

Canidoit, simple test. Run full mix through. Something with a nice full tight low. EQ Out. Listen, all switches OFF. Pot settings don't matter. Switch the EQ in. The low mid on down should drop noticeably. 

If so do the jump as described. As soon as you see the bottom of the boards you will see the points I am talking about right away from the description. They are easy ones to find, in this case.

Your map of the 51X PSU came in handy as I did a custom build one for this same client. 

I might get a chance to post an AP plot later on, before and after.

Thanks again guys,

James

 

[jrowell]

Oh yes, certainly nothing lacking overall.

Issue is only there when LF band is OFF. It did show with an LF freq selected, and not cut or boost. It did not affect full cut or boost. I did not check medium amounts of cut/boost. Logic says it would change things. Fixing the issue did change the shape at full boost, just a bit.

Not having that connection does change the filter arrangement in the LF. Period.

So usually not going to show up, under normal use, unless you use the other bands only, and follow good practice and switch unused bands off.

Or you are a nerd like me and do freq plots on an EQ in, with no frequencies selected, to see how close to bypass the response is.

You could hear it big time anyways. There wasn't a need to really plot it.

There is no real way to make up the difference, as there is no filter in the EQ to invert the curve.

My other tweaks were pretty small things.

As I said, for line in EQ only, this is superior to the original.

Lower distortion
Lower noise
Higher Input Headroom
Simpler Signal Path
More Frequencies
More Flexible Sound

Outstanding Peter,

James