agedhorse

13 hours ago, chris_b said:

Hold on. . . . an HPF isn't a prerequisite for a good bass sound, or even a good bass amp.

 

There have been bass players using classic rigs and sounding great for the last 70 years and HPF's have only become a "thing" in the last 2 or 3.

 

Choose the amp that sounds right.

Yes, but a lot of bass player tonal expectations have changed as well as a need for more low frequency extension without sacrificing articulation. Of course HPF's have been used on bass channels in the studio and in live sound for decades, so IMO it's not a fad but an evolution in response to evolution.

On 17/04/2022 at 12:57, Woodinblack said:

wasn't talking about a 3 year old amp, I wouldn't expect it to be anything other than perfect at that age, and I wouldn't routinely change anything.

I was referring to when you get one of those old valve amps from the 60s or 70s

 

 

I was addressing your comment about 3 year old amps and tubes, you suggested being more worried about caps. I now see that you also mentioned old amps.

7 hours ago, Woodinblack said:

 

Why not? They have a lifespan of about 30,000 hours, so if they have been gigged for 3 hours every night for 3 years you would still have another 6 years of the same schedule before they are getting towards their ends of life.

 

If I picked up an old amp for a recondition I would be far more concerned about the conditions of the capacitors than the valves.

Preamp tubes/valves when designed reasonably are typically good for a lifespan pf between 7,500 and 10,000 hours with some that will make it to 15,000 hours and some failing earlier. I see so many perfectly good tubes/valves replaced without any consideration that what's being installed may in fact have higher failure rates due to infant mortality (first ~200 hours)

On a 3 years old amp, capacitors aren't even barely "broken in". Typical lifespans when designed/selected properly runs in the 15,000 - 30,000 hour range, but I have some that I have seen well beyond that. I have however seen a lot of damage from folks who think a capacitor change-out is a maintenance item that should be done every 10 year or so (fueled by a bunch of bad information on the internet). 

7 hours ago, stevie said:

This is all a bit of a strawman. The instructions for assembling the crossover are on page 3. We're not using a PCB; we're using a chocolate block. The resistor is fitted against the chocolate block and taped (or tie-wrapped) to it, and the chocolate block is then screwed to the cabinet. If you wire it up this way, there is no chance of the resistor wires breaking.

 

The heaviest component isn't actually the resistor - it's the coil. And the advice there is to screw the coil directly to the cabinet.

My comments were general in nature, all heavy components need to be securely mounted regardless of how they are used.  I would not recommend using tape to mount a component that's likely to get hot. 

That's classic damage from a hard fall (either shipping or a gigging load-in/out gone terribly wrong). There are cracks in the baffle, the baskets are clearly distorted at the mounting screws and it's likely that there's more damage that is not yet uncovered. If the top 2 drivers are damaged, it's common for there to be more drivers with damage. This is a older, heavy cabinet without the value (IMO) to justify repairing (or replacing) the baffle, and drivers (even if only 4 drivers are damaged). When the cost of a proper repair exceeds the value of the cabinet, it's time to look at other options.

Regarding reconing, there's no way a pro recone shop would recone a speaker with a distorted basket, the chances of success are very low and nobody wants to warranty (and eat the cost) of a repair that they know is not right.

If the cabinet works ok for his application as is, I recommend leaving well enough alone. The less it's moved around, the better. As soon as you start taking it apart it's almost certain that it won't go back together without bigger problems than he has now. 

I did post but the post is gone. 
 

That’s due to catastrophic damage from a fall, bending the sheet metal. 
 

I am working with the op already on this.

1 hour ago, Dad3353 said:

Another option is to use an array of smaller, lighter resistors, calculated to have the same overall resistance and power handling, but less subject to shocks. As the power is shared, they have less need to be 'in the air', and thus less prone to damage. Four 4.7 Ohm 5W resistors in series/parallel, for example. Just a thought. 

Yes, this is sometimes done for mechanical reasons (especially with surface mount components, which obviously doesn't apply here). Smaller components have lower individual mass combined with a lower center of gravity.

On 11/04/2022 at 05:27, Stub Mandrel said:

Make sure the resistor is mounted so air can move freely around it.

It still needs to be mechanically secured or damage to the leads and/or PCB will result when the cabinet takes even a minor tumble. Most 20 watt parts have bumps in the bottom for this purpose, most 10 watt parts do not, and don’t need it with FR-4 PCBs.

When using heavier parts (like 20 watt resistors), provided the smaller part is properly specified, I see more mechanical damage from the larger parts being not well secured to the PCB. With the larger resistors, they must be mechanically secured in addition to being soldered. All it takes is the cabinet falling over to cause such mechanical damage.

6 hours ago, EchiDna said:

 

Seems my build is being hamstrung by a mis-labelled 4.7k ohm resistor and the horn is not getting any signal at all! That will teach me to build something without measuring the devices...

 

before I buy the correct 4.7ohm item, is there an ideal wattage? is 5w large enough? 

 

Cheers

 

  

10 watts will be plenty, multiply the (~25W) RMS power rating of the compression driver by~ 1/3 (the ratio of 4.7 ohms / 8 ohms) and you will see a maximum power dissipation of about 8.25W, which is pretty much the absolute worst case that the resistor will see. In actuality, given the crossover frequency and the power spectrum density for bass guitar, it will be about 1/2 of this value.  I have used this formula and approach in commercial speakers for decades without any problems.

None of the Subway amps require a load to operate safely.

Distortion and square waves don’t obliterate speakers any more than an undistorted signal of equivalent RMS power, and in fact is easier on a speaker mechanically.

A square wave of the same peak voltage as a sine wave has twice the thermal power but the same mechanical power. This is probably the root of most misunderstanding about the topic. 
 

Now peak power is something entirely different, a sine wave always has a peak power that’s double the RMS value, it’s purely two ways of using math to describe the same thing. 

Just following up with a conversation w/ Dave over on TB so that you have a better idea about what's going on.

I just heard about this decision this morning, I'm really sorry about this.

The compliance issues aren't the issue with the bass gear as they are already globally compliant, but the supply chain pressures just won't let up. As soon as we solve one shortage, something else comes along to create a new issue and it's darn near daily these days.

The decision was made to wait until these problems are resolved (on both the guitar and bass side) before re-starting things in the EU and UK. It's understandable why they made this decision, I absolutely acknowledge that it's frustrating for you (and for me too, for different reasons).

We are seeing lead times on a few parts approaching 60 weeks, and lead times are increasing on some parts that already have scheduled delivery dates, it's a moving target. It's something that's out of anybody's control, and it's even worse on the guitar side with tubes and certain specialty capacitors/resistors, alternate sources of some parts affect safety compliance and require new approvals.

Again, I am as sorry as you guys are about this, and I appreciate the few PM's I have received that were refreshingly respectful. 

On 01/04/2022 at 09:22, Dan Dare said:

 

Well of course it will. Nobody, least of all me, said it wouldn't. The margin may not be as wide as some assert, mind. As I said, I appreciate that you wish to bark your wares, but you are arguing at crossed purposes with me.

 

Weight, fit/finish, quality of covering, hardware and grille may enhance pride of ownership, but they have no benefit as far as performance is concerned.

 

Once again, you appear to believe that I am ignorant and have no experience of quality gear. You are mistaken.

Just to be clear, I have designed products for many brands and at different performance levels.

Fit/finish, quality of the covering, hardware and grille are all part of performance, as is size and weight, sensitivity, bandwidth (which tend to go along with higher quality, more expensive components). 

This has nothing to do with "barking my wares", as you have no idea who I have designed for other than what I have disclosed in my profile. Please stop with the personal attacks, I don't know what I may have done to you to deserve this, but it goes beyond disagreeing.

On 01/04/2022 at 00:58, barkin said:

As we're talking about the signal being sent to the cab, does it matter if any distortion is from an overdriven amp or a pedal?

I suspect not.

It doesn't matter where the distortion comes from, the distorted signal and the level is what matters to the speaker.

[deleted duplicate post]

On 30/03/2022 at 00:37, Dan Dare said:

 

Read what I said again. I did not say there is "little difference in drivers". I was referring to cabinets. Of course, I appreciate that paying more for a driver generally equates to better performance, but the cabinet is key. A modest driver in a well matched cab will give a better account of itself than an expensive one in a poorly designed cab'. The Basschat 1x12, which uses a reasonably priced Beyma driver in a simple/cheap to build but well designed box, is a case in point.

 

Look at cabs from the major manufacturers at any price point and you will see they are pretty close in size, design and performance. Many use the same or similar Eminence drivers. Eminence publish detailed performance figures and even suggest suitable cabinet sizes, so anyone with WinSD or similar can devise a suitable cab for their products

 

I "don't know this (yet)"? I actually use PJB cabs, which are not exactly bargain basement. I bought them because I tried them against the alternatives and preferred them. Just my preference. Others will have different opinions.

 

Perhaps, as you are a designer/manufacturer, it is in your interest to promote the notion that the differences are greater than they are and that paying more for your wares is worthwhile. 

I comprehended what you wrote plenty fine and you were clear in your assertion of both drivers and cabinets.

As a designer, I have designed commercially many cabinets including high end cabinets, middle of the road and those designed to a strict budget. There is an easily measured difference in all aspects of performance (as well as weight, fit/finish, quality of covering, hardware and grille) that goes along with the difference in price.

Real designers/engineers don't use vendor suggested cabinet designs because they have as much understanding of the principles behind the designs as the vendor's designers, and some of us have designed drivers as well when that's what's necessary to achieve the desired goals. Software (especially notoriously buggy software like WinISD) does not make somebody a true speaker designer. Understanding the way the various parameters trade off, the real world implications of what something looks like and calculates out to real world performance (and reliability) goes back to the basic principles, the math and a lot of experience. 

I agree that matching of the box to the driver is important to the total performance, but when you take a higher quality driver in a well designed box it will generally outperform by a wide margin a lower quality (or "budget") in an equally well designed box. This is why some products use more expensive components, because some players are looking for better than average performance, fit, finish, etc.

4 hours ago, Dan Dare said:

An amp malfunction is likely to damage any cab, same make or not. A cab is just a drive unit (or units) in a box, plus a few bits of wire and input connectors. A lot of bass cab manufacturers use the same or similar drive units (often from Eminence). The goals of the designers may differ, but not to any major extent. Nearly all are some type of reflex design. Of course, manufacturers big up how unique their take on bass cabs is, but the truth is there's little difference. Mix and match to your heart's content and find the combination that suits you. As long as impedance and power handling match, you'll be good.

If this were the case, if there was little difference in drivers, then why would some designers choose expensive drivers over cheap drivers?

Because in most cases, drivers with higher performance cost more (sometimes a lot more). Yes, driver performance can be very different from model to model, and some designers actually have a good idea of what players are looking for and are willing to spend to achieve this. You just don't know this (yet).  

Fortunately, I can design around whatever performance I need, and the cost doesn't matter all that much for our customer provided the speaker delivers the necessary performance in the size and weight box that the player is willing to accept. It's actually nice to design around performance and not have to worry about the cost (within reason), and for those players that feel that the cost is more important than performance, there are plenty of other options out there.

250 watts RMS is a (reasonably) clear term meaning that it's the thermal limit without the additional information regarding mechanical limits. Anything beyond this is speculation, and if you were to damage the cabinet with 500 watts, the question would then arise about what that 500 watts really means in terms of any warranty coverage.

Now it's possibly that the 500 watts is being used as a representation of "program" power handling, but since program power is generally a thermal rating as well, in practice it really represents a reduction in the crest factor of the test signal waveform (an increase in thermal duty cycle). 

It clearly does not apply to distorted signal, from my reading of that statement.

Regarding the use of the amp in question, I would recommend a healthy dose of caution and good judgement. The ShuttleMax 9.0 is rated at 500 watts RMS into 8 ohms, certainly enough to cause damage without good judgement.

Is the 300 watts in the marketing material "RMS" or "program" (2x the RMS value) or "peak" (4x the RMS value)?  The details are important.

On 14/03/2022 at 11:56, Sibob said:

I couldn’t sell mine quick enough, horrible thing haha.

YMMV as always.

 

Si 

That’s too bad, but it is a fairly heavily voiced amp, and if the voicing isn’t your cup of tea then it’s not a good choice.

Thousands were sold and there is still a robust used market for these amps.

I still get £261 with the courier fee, does VAT actually apply to the cost of shipping? I thought it was just materials and labor at the retail level.

Generally, repair labor is excluded from our sales tax, only the materials are taxed. Slowly we are creeping up to European levels, some areas of our country are now over 10%. 

By my math, it’s about 250 not 300.

When a resistor fails, it's almost always collateral damage from other failures that are not visually obvious. Replacing the resistor just burns up another perfectly good part and ultimately causes additional damage.

Parallel amp mode is 2 separate channels driven by the same signal of the same polarity. This requires a speaker on each amp channel.

Bridged amp mode is 2 amp channels, driven by a common signal with opposing polarity. A single speaker load is placed between the speaker outputs of the two channels.