Compact desktop line mixer?

[Newmarket]

NE5532/34?

Yeah - not sure you got my SoH there tbh

There is more to than just EMI.

So called "Faster" Op-Amp's will have a higher frequency corner where distortion rises. Many quite fast ones are flat to ~ 10kHz and some to 20kHz and even 100kHz.

This means high frequency intermodulation especially is reduced.

Yes - I could have referenced RF rather than RFI (tough crowd ). But my basic point was to not have the opamp / active circuitry "see" any unnecessary signal frequency.

That's a 10MHz Op-Amp, 13V/uS slew rate. Fastish. And it's not a simple integrator compensated Op-Amp.

Yes. My basic point was that as a teenager with little money - spending that amount on a single opamp was not tenable.
The "hobbyist" shop was somewhat comedic. It would typically be shut for lunch and a queue of very serious hobbyists would form. Woe betide you if you didn't know exactly what you required when you got to the front of the queue. Said items - resistors / capacitors / transistors etc. - would be retrieved from various boxes / drawers / tobacco tins etc. by a grumpy man with a big unkempt beard

That's still a MHz Op-Amp (3MHz) and it's also 13V/uS Slew rate. So the output can change as fast as that of the 553X.

Yes. For clarity - not suggesting GBW is a problem here.

Distortion is high, but for a Bass FX that's a good thing.

Well if you drive them hard enough. Interestingly the Sansamp Bass Driver/DI uses some CMOS opamps (at least according to any documentation I have seen) while the Behringer BDI21 "clone" appears to use TLxxx or similar IIRC.

It's bloody noisy though, noisier than a bunch of teen chav girls at their pregnant friends Hen do after the third round of shots.

Thor

Question of voltage noise Vs current noise. Latter becomes important wrt Hi-Z sources eg typical passive bass.
But yes we can do better now than TL07x or related LF351.
I'll leave the social observations to yourself

 

[thor.zmt]

Yes - I could have referenced RF rather than RFI (tough crowd ). But my basic point was to not have the opamp / active circuitry "see" any unnecessary signal frequency.

Given we now define as at least 40kHz bandwidth (my phone does that on a Bluetooth link), 40kHz is signal.

The "hobbyist" shop was somewhat comedic. It would typically be shut for lunch and a queue of very serious hobbyists would form. Woe betide you if you didn't know exactly what you required when you got to the front of the queue. Said items - resistors / capacitors / transistors etc. - would be retrieved from various boxes / drawers / tobacco tins etc. by a grumpy man with a big unkempt beard

Cricklewood Electronic, by the sound of it. Near the pink rupee, best kashmiri curry in London.

Well if you drive them hard enough. Interestingly the Sansamp Bass Driver/DI uses some CMOS opamps (at least according to any documentation I have seen) while the Behringer BDI21 "clone" appears to use TLxxx or similar IIRC.

I upgraded the Behringer clown with CMOS Op-Amp's and few extra mods. It's very good that way. I made some "utility cabinets" with a nice "hifi-ish" 12" Bicone driver and a 100W plate amp (full range) that jacked into various of the modded Behringer DI + boxes for musicians to hear themselves.

Question of voltage noise Vs current noise.

Trivial yo give the 5534 a 1.5nV|/Hz J-Fet frontend. Or add a J113 buffer before a 553X. Or go discrete. Tubes works actually pretty well there. In those days old tube TV's from scrap would have cost nothing.

No need to make excuses.

Thor

 

[Newmarket]

Given we now define as at least 40kHz bandwidth (my phone does that on a Bluetooth link), 40kHz is signal.

Yes. I was thinking a lot higher frequency.

Cricklewood Electronic, by the sound of it. Near the pink rupee, best kashmiri curry in London.

No. This wasn't in London. Marks in the Wyndham Arcade in Cardiff (also a larger shop in Newport).

I upgraded the Behringer clown with CMOS Op-Amp's and few extra mods. It's very good that way. I made some "utility cabinets" with a nice "hifi-ish" 12" Bicone driver and a 100W plate amp (full range) that jacked into various of the modded Behringer DI + boxes for musicians to hear themselves.

Which CMOS opamps ?

Trivial yo give the 5534 a 1.5nV|/Hz J-Fet frontend. Or add a J113 buffer before a 553X. Or go discrete. Tubes works actually pretty well there. In those days old tube TV's from scrap would have cost nothing.

Yes. For my own DIY boxes I've often done something along those lines. But pedal / amp hobbyists often want simplicity in circuit design and low component count. And fact is that most find TL07x perfectly acceptable. But personally I've always tended to go a bit further. Whether justified in audible terms I'm not sure. But having measured this stuff years ago it's my prejudice I can just about remember TVs with valves (tubes). Mainly due to a burning smell when they failed in one I was gifted by a sister who managed a TV rental shop where they were came back as people changed to solid state.
More familiar with valve radios.

 

[thor.zmt]

No. This wasn't in London. Marks in the Wyndham Arcade in Cardiff (also a larger shop in Newport).

I see, there used to be shops like that everywhere. In Cricklewood I befriended the grumpy old guy running the place and could just go into the back and root around for cool stuff.

At the front, he made the Soup Nazi look personable, service minded and very nice...

Which CMOS opamps ?

OPA165X / OPA167X

I can just about remember TVs with valves (tubes). Mainly due to a burning smell when they failed in one I was gifted by a sister who managed a TV rental shop where they were came back as people changed to solid state.
More familiar with valve radios.

Same really. Just no picture tube and extra high voltages to shock the Soup Nazi's soup out of you if after eating it you go back to work repairing tube TV's and the food induced semi-coma makes you careless...

Mind you, the HT on the 100W Marshall tube Head also packs a nice punch.

Thor

 

[Newmarket]

I see, there used to be shops like that everywhere. In Cricklewood I befriended the grumpy old guy running the place and could just go into the back and root around for cool stuff.

Yes. Cricklewood was a well know name outside London - adverts in electronics magazines of the day.
It's very difficult to buy components in real shops now in UK. The Maplin chain went out of business a good few years back now.
Even an RS Trade Counter just by Gatwick airport that I used to use for urgent work purchases closed. Despite being in an Industrial area.

OPA165X / OPA167X

Thanks. Are you able to say what benefits they brought ?
I guess the other mods were related to the frequency response - built in "mid-scoop" and "cabinet simulation" filter ?

Same really. Just no picture tube and extra high voltages to shock the Soup Nazi's soup out of you if after eating it you go back to work repairing tube TV's and the food induced semi-coma makes you careless...

Mind you, the HT on the 100W Marshall tube Head also packs a nice punch.

As it happens I had 38kV unit running on test in the lab earlier pre / post lunch

 

[JohnRoberts]

Question of voltage noise Vs current noise. Latter becomes important wrt Hi-Z sources eg typical passive bass.
But yes we can do better now than TL07x or related LF351.
I'll leave the social observations to yourself

Not to cut in on this dance party but passive bass guitar pickups are not as high impedance as lead guitar pickups FWIW.

JR

 

[Newmarket]

Not to cut in on this dance party but passive bass guitar pickups are not as high impedance as lead guitar pickups FWIW.

JR

In general yes. But there is overlap.
I have a MM type Bass Humbucker (fwiw an Ibanez ATK200 pickup that went microphonic).
Each coil measures around 1.42H - so in the usual parallel config about 0.7H (Simple handheld LCR meter readings at 1kHz)
OTOH a Rickenbacker 4003 pickup van read over 4H - well into single coil Strat territory.
All high impedance in the context of the "Low Z" pro audio world.

 

[thor.zmt]

Thanks. Are you able to say what benefits they brought ?

The Originals Musicians just didn't like. They didn't like the sound. Perhaps "foggy" would be a way of saying it. Maybe a mix of too much noise and roll-off/increased HF distortion. It didn't "sound right", there was a preference to go directly into the mixer from their digital pedals.

After the changes (including a range of passive parts also), which were not done in a controlled way and which included de-branding, the Behringer Boxes were liked and felt to sound better than straight.

This applied to both Bass and Guitar. I changed the circuits from the originals to in effect emulating a Marshall Stack with a Dual 4 X 12" Stack (guitar) and Ampeg SVT with the 8 X 10" Ampeg Speakers.

This lead to very different overdrive circuits, Tone Controls and Speaker Emulator frequency responses.

In both cases speakers were relatively flat response 12" Dual Cone Drivers ~ 96dB/W (Chinese OEM Samples) in modest sealed boxes (actually Car Subwoofer Boxes, these Trapezoids) with a 50W/8R Class AB solid state Amp driving them. So the "tone" was not from the speakers and amp.

That said, I also use these IC's in more demanding applications and they do extremely well, in view of pricing.

Calling them CMOS is of course TECHNICALLY correct (they are), but a bit tongue in Cheek:



The performance is more in line with the best previous Generation J-Fet types like OPA627/827...

As it happens I had 38kV unit running on test in the lab earlier pre / post lunch

If there is current behind that that's a lot of ouch....

Thor

 

[Newmarket]

The Originals Musicians just didn't like. They didn't like the sound. Perhaps "foggy" would be a way of saying it. Maybe a mix of too much noise and roll-off/increased HF distortion. It didn't "sound right", there was a preference to go directly into the mixer from their digital pedals.

After the changes (including a range of passive parts also), which were not done in a controlled way and which included de-branding, the Behringer Boxes were liked and felt to sound better than straight.

In both cases speakers were relatively flat response 12" Dual Cone Drivers ~ 96dB/W (Chinese OEM Samples) in modest sealed boxes with a 50W Class AB solid stat Amp driving them. So the "tone" was not from the speakers and amp.

This applied to both Bass and Guitar. I changed the circuits from the originals to in effect emulating a Marshall Stack with a Dual 4 X 12" Stack (guitar) and Ampeg SVT with the 8 X 10" Ampeg Speakers.

This lead to very different overdrive circuits, Tone Controle and Speaker Emulator frequency responses.

That said, I also use these IC's in more demanding applications and they do extremely well, in view of pricing.

Thanks for the info'

If there is current behind that that's a lot of outch....

It's "Low Power" kit - should limit at well under 300uA.

 

[sahib]

....
It's very difficult to buy components in real shops now in UK.

I have mentioned this before. In Istanbul there are two main hubs for electronic components. One in European and the other in Anatolian side. You can still walk into a shop and buy components in singles. Even a single resistor. Often you find gems.

The Maplin chain went out of business a good few years back now.

And I could not be happier. Their Glasgow branch was run by a bunch of arrogant guys and if they did not like your look they would follow you. I once had an argument with one who was breathing over my neck when I was looking around for a connector.

Even an RS Trade Counter just by Gatwick airport that I used to use for urgent work purchases closed. Despite being in an Industrial area.

We still have it here in Glasgow and they are all the sweetest guys ever. I have been a customer for over 30 years now.

 

[JohnRoberts]

In general yes. But there is overlap.
I have a MM type Bass Humbucker (fwiw an Ibanez ATK200 pickup that went microphonic).
Each coil measures around 1.42H - so in the usual parallel config about 0.7H (Simple handheld LCR meter readings at 1kHz)
OTOH a Rickenbacker 4003 pickup van read over 4H - well into single coil Strat territory.
All high impedance in the context of the "Low Z" pro audio world.

I will defer to your empirical data... I was sharing what I was told by a bass amp designer last century when I did some in-house research for an active direct box I was designing. I tried to ask the guitar division guy responsible for designing the pickups and he was not able to share anything in useful engineering terms.

JR

 

[ruffrecords]

I see, there used to be shops like that everywhere. In Cricklewood I befriended the grumpy old guy running the place and could just go into the back and root around for cool stuff.

At the risk of parodying Monty Python, you were lucky to have shops like that. Where I lived there was nothing like that. Luckily I joined the local amateur radio club when I was 11. One of the (grown up) members ran a TV repair shop. He invited a couple of us youngsters round his house one weekend and led us into his back garden. There we found what to us looked like a 10 foot pile of old TV chassis. He passed us both a pair of snips and said "Help yourselves lads".

These days he would probably have been arrested just for talking to us.

Cheers

Ian

 

[Newmarket]

I will defer to your empirical data... I was sharing what I was told by a bass amp designer last century when I did some in-house research for an active direct box I was designing. I tried to ask the guitar division guy responsible for designing the pickups and he was not able to share anything in useful engineering terms.

JR

Well in general I think it's true that pickups for the wimpy six string machines are lower, though still high, inductance.
Okay - I confess I'm biased toward the low end machine as that's my instrument !
But the range of values is wide. Esp wrt "Hot" guitar pickups with more inductance, higher output and (all else being equal) less top end (in an electric guitar sense which is really mid range)
And tbh, if you want a parallel to "Audio Phoolery" then the marketing of pickups is a good option.
Amp input impedance is also often oversimplified in its effect. A typical guitar / bass pickup typically already has a 250K or 500K potentiometer across it to 0V as a volume control and then a Variable R / fixed C series network as a Tone Control. Interesting in itself as in conjunction with the pickup inductance it shifts a resonant peak before the hf roll off.
Having a lower input impedance on bass guitar can be interesting - there's a preamp manufacturer who has made explicit use of this as an option but the name escapes me atm. Aside from the level drop and frequency response changes it dampens the sustain and that is often a desired effect.
But yes, it does seem to me that lower input impedances are more acceptable with bass.
Related to this - a previous discussion with Cyril Jones (Raindirk) about a DI/Reamp box he made/sold. It has options for a pre-transformer buffered input or straight into the transformer. It seems guitar players mostly favoured the buffered input whilst lots of bass players went straight into the transformer.
It was well above my budget so I don't have one and I didn't find out the transformer ratio. I did ask him some years later but he didn't have the info.
But let's say its 10:1 so basically multiplying impedance by x100. Into a typical mic pre - let's say 2k2 then that still only comes to 220K (in parallel with the internal bass vol/control networks).

 

[sahib]

Around about 20 years ago I had bought some Triad transformers with a rated impedance 700k :7k. I had made a passive DI and it had sounded great into mic-input, particularly with my (former) Musicman Silhoutte). I don't know what happened to the DI (as I had not played electric properly for over 15 years now) but I still have few transformers in the boxes.

This is (younger) me wiring it. By the way, the yellow soldering iron you see in the background died only about two years ago. I had not even changed the tip.

 

[Newmarket]

And I could not be happier. Their Glasgow branch was run by a bunch of arrogant guys and if they did not like your look they would follow you. I once had an argument with one who was breathing over my neck when I was looking around for a connector.

Oooh - that sounds unpleasant and not very '"Glasgow" - although tbf I'm judging on the basis of a short break there last year so hardly the lived experience
I always had good service at the Maplins I used - mainly Brighton and Crawley. Wrt the business itself it seemed to me to "go wrong" when the stores started to focus on bigger ticket items - RC stuff etc and particular brands of eg SSD and Smart Home stuff. I can see why - I mean how much money can you make selling packs of components etc in a retail location with relatively large stores,
But it was great place to go and get that length of double screened cable that you needed right then ! And the nostalgia of the big paper catalogue.

We still have it here in Glasgow and they are all the sweetest guys ever. I have been a customer for over 30 years now.

That sounds better. Yes - I found the trade outlet very useful and helpful.
And sometimes I'd order online to have stuff picked up from there as it was sometimes better than waiting at the factory for the delivery if not paying for guaranteed timed delivery.
I didn't actually find out it had closed until a few years after it did so as I no longer worked in Crawley but was going to place a personal order for my diy activities.