BillFitzmaurice.info

I think it may be new amp time. I bought a second hand matrix uk power 1300 a few years back and it needed fixing with capacitors. Then on my annual outside gig last year I only measured about 28volts and it was 'clipping' - it was on tops duty so it was just about coping - that amp should be good for over 50v with an 8 ohm load! Should I look into getting it fixed? What is the likely problem and cost of parts? Or is it just new amp time and use it for monitors? ...I've been looking at this: https://m.thomann.de/gb/the_tamp_tsa_47 ... 1495989804

and wonder if it's the right sort of spec for expandability. The one thing I do like is that if I doubled up subs on one channel and got a 4 ohm load, there's still enough power for a notional 50volts and it's not running at the max. The other side of the issue is too much power - on FOH at least it goes through the PA+ but on monitors...?

I've had a check in my mind about the TSA 4-700 after reading reviews. They say it can be noisy if the inputs are set wide open. I know there's different schools of thought on that - settings the amp inputs to the max - but I don't want to be overly compromising by taking an easy catch-all solution, so I've thought maybe about a different amp - the QSC GX5 - as maybe a 'reference' amp for me, but one that will handle a pair of 300w subs on one channel - it's more of a standard topology than a switch mode job. There's still plenty of other 4 channel amps that would do for monitoring in future that don't need to be as high power per channel (or as 'clean') as FOH requires.

I'd appreciate any thoughts on this before I spend new amp money. ...I don't think I've enjoyed having my ass bitten with second hand amps.

Charles, very few of us can truthfully comment on Thomann offerings, as we don't live in the EU. However, Thomann has a pretty good reputation for standing by what they sell. As for using all 4 channels, I would think 1 for mono tops, 1 for subs and 2 for monitors would be perfect.

As far as noise is concerned, just remember one thing: this is NOT Hi-Fi! It's simply a matter of what you will tolerate. TBH, once the music is running, nobody will give a shit....

Thanks DJ.

I was talking to a friend last night and he said that subs and tops are best not run on the same amp due to crosstalk, mainly from sub signal harmonics interfering with tops signal in the amp. Is this specific subs to tops crosstalk audible?

Charles Jenkinson wrote:I was talking to a friend last night and he said that subs and tops are best not run on the same amp due to crosstalk, mainly from sub signal harmonics interfering with tops signal in the amp. Is this specific subs to tops crosstalk audible?

I'm going to let someone more educated and experienced than me, answer this one. As I understand it, amplifier "cross-talk" has not been an issue for quite some time.

If you download the manual .PDF from Thomann, the specs list cross-talk @ 1 KHz, 10% power to be <-80dB. IOW, your friend is about 30 or so years behind the times. You should not have any problems running the amp as I stated in my previous post.

Regarding running subs and tops on the same amp, it depends on the amp. Most modern amps can handle it with no problems, especially in low to moderate volume settings. If you're really pushing things to the limit, like running both sides of the amp at 4 ohms (or, <gasp> 2 ohms) and running full out volume, you may begin to notice that the power supply sags a bit. A big hit in the subs can cause a small distortion in the tops. This is not crosstalk, just the amp running out of current capacity (Watts DO matter, contrary to mantra around here).

Add to that that most of the time you need more power for subs than tops, and that there are many benefits to running in stereo, it's usually a good idea to keep tops and subs on a seperate amp.

That said, I've sometimes used just one amp, or one four channel amp, and had no problems... but only because it was within the capabilities of the amp. Newer lightweight Class D amps are more susceptible to running out of current capacity in my experience, but it theoretically can affect old iron too.

I bought the Thomann amp, and used it on Saturday to run two subs on channels A & B, and two tops in stereo on channels C & D. There wasn't any noticeable degradation of sound as per the discussions on crosstalk.

It was useful to have to reset the limiter on the PA+ for the new amp, because I inadvertently deleted the existing user setup I've been using for subs and tops - it was wrong anyway - none of the factory presets in the PA+ have a mono low (ML) out, they're always left and right, so I had to figure out how to do that. The limiter needed a good 20dB of reduction dialling in to bring 70 odd volts down to just under 50v at full signal. I probably set the crossover a bit low at 90Hz, considering I was using a W8 for a bit of booth infill, so I would change that next time.

Very pleased with it so far, and quite a chunk of amplifier for the money, and with the 3 yr.warranty to boot, it seems a no brainer. What was far more obvious variability with respect to the overall sound reproduced (eq wise) was the use of different sources for playing tracks. One of the sources - a Samsung phone was quite poor with its DAC's interpretation of a high quality spotify file. We will watch out for that another time.

If running different pass bands from the same amp were a real-world problem, Crown wouldn't have made the Macrotech 36x12.

David Raehn wrote:If running different pass bands from the same amp were a real-world problem, Crown wouldn't have made the Macrotech 36x12.

Gotta admit....I'd never seen that one!

I guess it's a northeast thing.....

https://clairusedgear.com/collections/a ... -amplifier

Works well with these....

https://clairusedgear.com/collections/s ... roducts/s4

David Raehn wrote:I guess it's a northeast thing.....

https://clairusedgear.com/collections/a ... -amplifier

Works well with these....

https://clairusedgear.com/collections/s ... roducts/s4

Gotta love those old cabs.....and only 425 pounds!

I was at a show with their slightly smaller cousins on 1 July. These boxes had dual 15, dual 10s and dual 2" comps per box. 8 tops and 8 dual 18 subs.

Old school horsepower........

David Raehn wrote:I was at a show with their slightly smaller cousins on 1 July. These boxes had dual 15, dual 10s and dual 2" comps per box. 8 tops and 8 dual 18 subs.

Old school horsepower........

Man, I bet that was smokin'!

The same crew will be with me and my T48 / OT12 (4 each) rig in September. Same band, same engineer and techs. I hope they will be impressed.

Here's a sound check of the Thomann TSA 4-700.


Interesting, the Thomann is Class H, 12.5 kg weight. Double the weight of the the Class D inuke NU4-6000.