agedhorse

3 hours ago, Treb said:

and that's where the HPF comes in handy...

Or essential...

9 hours ago, J.Wolf said:

Hey Andy! Certainly true, but I'm not clear on which comment you are responding to.

Your post above: 

"Totally, its a lot of power.  but really what it is, and what we were after is a lot of headroom, at ANY volume."

8 hours ago, bremen said:

All true.

 

My point, though, is that Bob Gallien says it was a deliberate decision to use a mere 2000uF reservoir caps in order to get a particular sound, and users of his amps enjoy their 'heft'.

 

So maybe, counter-intuitively; a stiff, conservatively rated power supply doesn't equate to a 'beefy/hefty' sound as conventional wisdom has it, but some sag is what's called for. In which case one of the possible reasons for some class D amps not sounding so great is that the switching power supplies in them are too good, too well regulated, not saggy enough.

 

As Deaddog remarks, valve amps sag and valve amps have heft. I wonder how much the HT rail on an SVT drops at full power.

 

I'm going to hook an olde fashioned unregulated linear power supply up to my classD amp, bypassing the smps, and see what happens. I suspect confirmation bias might win, though, so don't believe a word I say.

This kind of goes against all the mythical BS about an amp needing a big transformer and filter caps to sound “hefty”. 
 

There’s an awful lot of attributing cause and effect in the fade of multiple examples contrary to the premise. 

Note that the definition of headroom is available power that is NOT used. Once you use that power, it's no longer considered headroom. 

16 hours ago, Chienmortbb said:

Presumably that means that from the returns or aux inputs you get a much lower THD figure, more in line with the power module's base specs?

Yes, lower THD without the preamp, the output stage emulation algorithms are different than the gain stage algorithms. It also depends on the amp model, for example the TT-800 uses different algorithms than say the D-800 or 800+. 

It also depends on how hard the gain stage(s) and the output are driven, the character and distortion harmonics change with both level and frequency.

On 14/09/2024 at 07:27, DGBass said:

I suppose in reality a THD spec is only a sales differentiator at the end of the day for some folks. I would never claim I could tell the difference between 1% or 5% THD, or 700 and 800 watts. I'm more curious why some amp makers quote one and some don't. And why Ice Power ratings are different from the finished products they go into especially when they are higher. I only mentioned Mesa as an example where there isn't a figure on thier website. It might be in the user guide though.

The detailed specs are located in the back of each owner’s manual.

We specify the rated power at THD less that 10% because much of the harmonics are added in the preamp and power amp tube emulation circuits in addition to the tube preamps themselves (WD and TT) when driven hard.
 

It’s similar in concept to say the SVT which uses 5% THD, or the Darkglass amps that use ~20% THD (presumably because their drive circuits are the basis of their fundamental tone). 

2 hours ago, Bill Fitzmaurice said:

As best I can tell the cab internal volume is about 60 liters, so a 75 mm ID tube 35 mm long would give roughly 50Hz tuning. But the port velocity is off the charts. You need two, 120 mm long. 

Yeah, that would turn an electric bass into a tuba at those velocities

With OEM drivers, you can't assume that it has anywhere near the same TS parameters even if it looks "identical". The differences can be huge, thus impacting any modeling accuracy you hope to achieve.

13 hours ago, Chopthebass said:

Ok so if the cabs are stacked with the array horiz as it’s meant to be, it still means the four woofers end up in the non preferred arrangement. I assume this won’t matter? 

Correct, that’s exactly why I differentiated between the LF section and the mid-hi frequency sections as Bill also clarified.

7 hours ago, Downunderwonder said:

Worth mentioning the Genzler 'tweeter' array is doing a lot more than tweeting.

Correct.

They are designed to work stacked vertically, not side by side. The mid coverage pattern is defined by the mid element’s vertical orientation of the mid-high frequency array.

7 minutes ago, bremen said:

Ah well, we're in different leagues. The Sunday League post punk noisers I play with get what we're given, and enjoy the sound and smell of dying loudspeakers.

That's a tough market to earn a living in as a sound guy...

3 hours ago, bremen said:

You can choose?

Yes, often (or usually at the level I work at) you can. 

3 hours ago, bremen said:

So are bass speakers, Shirley? The ones I like are, anyway

The breakup in guitar speakers is quite different, and the cones/surrounds are designed differently in order to enhance the desired characteristics for different guitar styles. 
 

You won’t find the same types of cones and surrounds intended for breakup in bass speakers. The side effects are generally detrimental to what most bass players are looking for. 

1 hour ago, PinkMohawk said:

And yes, FOH can always f*** it up, but, they can f*** up your DI signal as well.

Only if you choose the wrong FOH guys...

53 minutes ago, JottoSW1 said:

I will have a look for the Peavey

Just note that there were some reliability issues, and I don't think that they support them anymore. This should factor into your decision.

10 hours ago, Stub Mandrel said:

 

I think we should (1) be clear that @jazzyvee is very much a pro and (2) his post was a reaction to a response to his rig when he posted it on Facebook, he already concluded the port would be 'devoid of many frequencies' and wondered why anyone would want to mike it up.

Understood, I was responding to the question about what a "pro" is. I should also extend my response to those players who go out of their way to ACT like a pro, and to note that there are pros who don't act this way also.

10 hours ago, Dan Dare said:

Mic'ing the bass rig in any manner is not the best way to go, imho. DI is better. Before anyone starts talking about "my tone/sound", it needs to be realised that the sound that works onstage often doesn't work in the mix out in the room - different acoustics, different rig, etc, etc. It's better for the sound man/woman to have a clean slate to work with.

It really depends, sometimes micing a cabinet works very well and sometimes a DI is better, which is why when I mic a cabinet I also like to have a DI so that if needed I have options.

1 hour ago, Stub Mandrel said:

 

Yes, but tell that to a guitar player...

Guitar is a very different beast. First of all we don't have to worry about the bottom octave which for bass is the hardest to mic accurately or successfully. The second reason is that the natural low pass effect of the speaker is used in combination with any distortion that may be used and it very much part of translating the electrical signal to an acoustic signal. This is why IR's are so much more common and useful (now) in the guitar world but not as useful in the bass world. Different sources require different tools for greater success.

A pro gig is gigs by pro musicians (who earn a substantial portion of their living in the music industry) and pro sound guys make their living providing sound to mostly professional acts.

There is a HUGE difference between real pros and those who think they are pros. Unfortunately you often discover the difference  between pros and non-pros after it's too late to do anything about it.

On 06/06/2024 at 01:25, Rich said:

Yes, the Signal Shape 'Mid Scoop' button on my Genz always remains disengaged.

I wish I could go back in time and tell my 22 year old self to stop trying to get a good sound with that stupid smiley EQ curve everybody used.

Different music styles, speakers and basses make this feature desired and useful to some players. 

Sure it’s entirely possible. The real challenges is the cost of development, testing and global safety/EMC certification for a component that’s very low production volume. 

Another ridiculous urban myth that I’ve never seen at a pro gig ever. 

No way to accurately predict the outcome. 

11 hours ago, PaulWarning said:

I'm not surprised, all they asked was a simple question, talk about making life difficult 🙂

What’s difficult about his question or the information that was provided? 
 

Often, a seemingly simple question doesn’t have a simple accurate answer and since the wrong answer (of an answer that’s out of context) can be dangerous, the additional information is in fact important. 

Ok, if the problem returns, Surrey Amps is handling Genz Benz and Mesa repairs for the UK. 

On 21/07/2024 at 04:50, itu said:

T = Träge = slow blow

F = Flink = fast

 

These are originally German terms.

 

About the diameter of a cable: Usually it is safer to use slightly larger diameteter than that specified, if the cable is in active use. Here active means gigging round the country (and for some of you: the world). As cables will be bent a lot, at some time the copper will be chipped to smaller pieces and the ability to carry the specified current will be less.

 

I have been amazed pretty often that so many bands have invested to equipment, but not to functional cables. When I joined one band long ago, their cables were just a mess in two or three plastic bags. Some cable was always missing, and the usage was harsh. I asked for a permission to buy new cables and some usable bag for them. The price tag made them thinking that these are serious stuff, and should be treated equally. 

 

I also love Velcros, as cables are much easier to handle individually than as a tangled mess.

My understanding is that T is the designator for time lag or time delay or timed opening fuses.

Looking at the IEC standards, there are T, TT (even slower opening), F and FF (even faster opening) but the TT and FF are specialty products that we won't see in the MI industry. These only apply to the 5mm x 20mm fuse type, the 6.3mm x 32mm fuses use different designators.

1 hour ago, Mottlefeeder said:

Thanks @agedhorse. 

 

So, from the table, for a 0.75mm^2 conductor (commonly used with moulded on 'kettle connectors' and rated at 6A) you can use a 10A fuse in a rewirable plug and a 13A fuse in a moulded on plug.

 

David

That's what the regulations say, I am not sure of the date of this data though. 

.75mm^2 is equivalent to our 19 AWG, and our 18 AWG (slightly larger) cordsets are permitted to be used on 20A branch circuits. 

This is specifically to prevent fire due to a fault in the cordset, it's not best practice for sizing to a load. In our industry, this is addressed under the safety regulations by providing an equipment located fuse or breaker (called an overcurrent protection device) that is sized in conjunction with the specified IEC cordset size. 

Since most equipment that we are talking about here is typically protected by a T6.3A or smaller fuse, and will work plenty fine (and safely) with a 75 mm^2 cordset.

There are a lot of quirky elements to this topic as you can see. Other countries and regions are even more convoluted.

5 hours ago, BassmanPaul said:

Another point is that the 4Ω cabinet will draw twice the power of the 8Ω box. That Ould be more than the speakers can safely handle..

 

Not necessarily. Using the Subway 115 and 215 as examples, the  8 ohm 115 is rated at 400 watts RMS, the 4 ohm 215 is rated at 800 warts RMS, when driven from the 2 ohm tap (switch position) each DRIVER receives 1/3 of the ~800 watt rated power or about 260 watts which is well below the rated power handling of the driver in those cabinets. Perfectly safe, perfectly good power match as well.

Here's the handy table from the owner's manual, and why I strongly recommend reading the owner's manuals for our products: