Chienmortbb

Your experience matters as your experience is so vast that I again I bow to your knowledge, and I am glad you put the myths about class D to rest. I have also repaired ICEPower modules (I blew them up 😀).

Are those the ones that make Amp Techs have nightmares?

Agreed and if Airbus/Boeing/Lockheed made speaker chassis they would be carbon fibre. I also agree that 7 years is not unreasonable for a speaker although many will go on decades longer.

THanks for that. The term basswood is used for all varieties in guitar building, so which grows in the far east?

Great find.

I will be honest that my training did not include valves and I am ready to be shot down by @agedhorse or any real expert. As I understand is, Sag in power supplies adds to the natural compression of valve amps that may or may not continue in the pre-amp stages and is certainly true of the output stages.HiFi would demand that an amplifier is not used in its non-linear region to maintain adequate distortion figures (THD or THD+n). Any type of compression, overdrive or fuzz increases the distortion. Of course sag occurs at higher power levels and also happens to some degree on solid state amps using an unregulated power supply. Sag is a form of current/voltage limiting.

Basswood Linden Lime are all the same family.

I think the SQ range are a step up from the CQ. As a pro mixer, it would expect all inputs to be balanced on XLRs. If you need a jack input, you need to input jacks then it would be DI'd.

More to the point is that they cannot guarantee how the driver is used, although they invite damage with 500W RMS (800W clean).

Much better than the water pipes analogy that they taught us a college.

I am not fit to exist in such exalted company.

Very close to a reply that I was going to post, The way to create a 4 ohm load is with two 8 ohm speakers in parallel. I would have gone on to explain that despite looking like a simple machine, the drivers we use are complex. When Beyma published power compression graphs, the loss in power stated at way below rated thermal power. If my memory serves correctly, most LF drivers at least in the Beyma range were approximately 1dB down on power by the time they had been driven to 1/3 of their right thermal power. At rated power, the compression had risen to over 3 dB. The 4 ohms us that many amplifiers cannot supply the extra current needed to achieve the extra power. If you look at an amplifier spec, and it’s 4 ohm power output is not double the 8 ohm power output, then it is likely that the power supply is not able to supply the required current. Taken all these factors into account, There is very little to gain, if any, in going for a 4 ohm driver/cabinet. Two 8 ohm cabs, stacked vertically, with a decent amp is much better.

I will leave that until later if you do not mind.

AC Power Can of worms time. In the old days, or should I say ye olde days, they needed a way to compare AC power with DC power. The way it was done was to rub two knights together They took a heating element and worked out how much AC voltage was required to raise the temperature of the heating element to that of a DC voltage. From that it was found, taking the Root Mean Squared of a number of voltage samples. If you like maths (math for our colonial cousins) look HERE. For the rest of us, the numbers 0.707 and 1.414 are the magic numbers. So if we know the peak value of a sine wave, either divide it by 1.414 or multiply by 0.707 to get the RMS voltage. So what does the mean? Let's look at European main voltage. Nominally 220 and nominally a sine wave. 220 x 1.414 = 311 volts peak. Of course, an AC voltage moved above and below zero volts. If you wanted to impress the opposite sex, you could quote the peak to peak value 311+311=622 volts. So peak to peak voltage is almost 3 times the RMS voltage. Now somewhere along the way some marketing "executive" found this out, opened the window and out went the truth. If you also take the peak to peak current and multiply the two together, you can get a power 9 times larger. Hi-Fi amps usually strive to keep the signal as clean as possible, with distortion figures of 0.01% or better at full power. Our pesky marketing guy also found that by quoting a distortion figure of 10% he got a higher power. I like to work at 1% THD+N for a power amp but Bugera Veyron quotes a power output of 2000 watts peak into 4 ohms. This approximates to just short of 700 watts RMS, so a loud amp but nowhere near 2000 watts. What if I am fed up listening to a sine wave? Firstly, what does a sine wave sound like? A flute or acoustic feedback/howlround. However, most of us do not play flute and a monotonous tone is no fun. Music is almost never a perfect sine wave. So you cannot use the shortcuts shown above. Luckily for Electronic Engineers, we can measure RMS voltages either on a True RMS voltmeter or Digital Oscilloscope. Otherwise, it is the long-winded equations seen at the link above.

DC Power The Power Law, as applied to electronics, takes the form P = V x I where I is current in Amperes or Amps, V = voltage in Volts P=I2 x R where I is current in Amperes or Amps, R is Resistance P= V2 / R where V = voltage in Volts, R is Resistance By using the Power Law and Ohm's Law, we can manipulate to find other values. Easy, so if P=V2 X R then if the voltage is 25 and the resistance is 8, or 78 watts. Not watts RMS or peak, just watts.

Resistance, Impedance and Ohms Law On another thread the old chestnut of amplifier power, valve amp magic etc. I thought it might help if I explained (I used the term explained loosely) what Watts and Ohms are and why Ohms Law matters. My qualifications 40 plus years in Electronics, 7 years study, an HND and had letter after my name but let lapse when fees were too high. I should say that as I try to simplify this, I realise how many other things are involved, so please forgive me for errors or mistakes. I will correct them as soon Ohms are the unit of measurement of resistance and impedance. The difference is that most electrical components, especially loudspeakers, exhibit resistance (DC) and Impedance (AC) and often capacitance. However, we will ignore capacitance here. Ohm's Law states V=I x R Or the voltage V = the current I x the resistance R (Z). If you have ever tried to measure a loudspeaker driver with a multimeter on the resistance range, it will read below the rated impedance. A Fane 12-500 has an Re of 5.6 ohms and a nominal impedance Z of 8 ohms. The Impedance is frequency dependant, and 8 ohms is usually the lowest load that the driver will present to the amplifier. If there is a passive crossover in the cabinet, this becomes a part of the impedance too.

If an amp is rated at 135W RMS (average) the maximum output fully distorted (a square wave) will give 191 watts. There is a thought that tubes or Thermionic Valves have some magic attached to them but they do not. The laws of physics, or in this case, the power law variant of Ohm's Law always applies.

Once is a mistake, twice or more is jazz.

Wem did both 4x10 and 4x12 columns.

I would be wary of designs their own class D module. Ampeg fell foul of this with the PF500.

I also have a VS Bassamp and the later Bassamp 100, both sound great. I have never thought of going to an HH Cab as the speakers may well be in a state of disrepair.

Probably better than you think, although there will not be a lot of either top or bottom. That sounds like a contradiction but the 4x12s stacked vertically aim the beam and those early 12s, rated at only 25-30 watts went higher than most modern 12s.

I did my engineering apprenticeship from ‘68 and engineering adopted the SI system way before then. Of course I learnt the Imperial system at school so like you, became adept at mentally transposing back and forward between the two systems. However the SI system is scientifically derived system, rather than one based on the arbitrary size of the monarch’s extremities.

Yes, the Colonies refuse to conform completely to the world standard. As the big guitar companies are from USA, they have traditionally used imperial measurements but none of my basses is USA made so all have metric truss rods and it is much easier to work in mm rather than fractions of an inch to set other aspects of setup.

The Allen key (hex wrench to those across the pond) supplied was a soft as poo so I ordered one, a long Draper one from Amazeballs. Could not get one before Monday anywhere else. It arrived today and made adjusting the truss rod easy. I set the relief by eye, as suggested and will measure it shortly. I just need to increase the string height a tad and it will be great.