EBS HD350 Advice

[patrikmarky]

Looking for some advice on a EBS HD350 …

I purchased one of these from a retailer last week and before buying I asked the minimum load as I’d heard these dropped to 2 ohms  but I was unsure …I was told it did dropped to 2 ohms and have subsequently gigged with 2 x 4 ohms cabs ..you’ve guessed it cooked the speakers in one cab and blown the amp ..looking at the back panel I can see where a novice could misunderstand this (In hindsight I should have investigated deeper ) but relied on the advice given from retailer  ..what I don’t understand is if its a 4ohm amp why does it say 8 or does it work from 8 ohm down to 2 ohm …

[pete.young]

I think the retailer is right, this head should have been capable of operating at 2 Ohm . The early models only allowed 4 or 8 Ohm operation and they were labelled 4 - 8  where yours says 2 - 8 .

 

You can get absolute confirmation by emailing EBS with the amp serial number.

 

So whatever fault caused this to blow up, I don't think it was because  you connected 2 4Ohm cabs to it.

[warwickhunt]

As @pete.young has said, your amp is capable of operating down to 2 ohms, often folk will advise against it as it 'might' be near its limits BUT that said it should still be safe!  

 

I've a feeling other factors are involved in this sad situation!  

[patrikmarky]

That’s good to hear ..possible fault on the amp has caused the speaker to blow ..though it’s beyond me why that could be the cause the  amp wasn’t peaking and was working at about 30% as I was amazed at the volume available.

[warwickhunt]

6 minutes ago, patrikmarky said:

That’s good to hear ..possible fault on the amp has caused the speaker to blow ..though it’s beyond me why that could be the cause the  amp wasn’t peaking and was working at about 30% as I was amazed at the volume available.

 

You would 'assume' so but personally I'd not rule out some other cause; be it cables, the cab, power supplied etc.

[patrikmarky]

The amp has definitely cooked ..never thought a dodgy cable  could cause that 🤔

[Mykesbass]

On 14/07/2024 at 14:52, patrikmarky said:

The amp has definitely cooked ..never thought a dodgy cable  could cause that 🤔

You didn't use a shielded instrument cable rather than a speaker cable?

 

Just seen they are speakons so that should rule that out.

Edited July 15 by Mykesbass

[patrikmarky]

Yes speakons ..it’s now going back to be looked at ..had no clipping I always watch that as been burnt by that before ..one thing I’d did notice was the fan runs constantly not sure if that should be the case on these older class A amps my GK legacy only comes on when needed ..

[agedhorse]

3 hours ago, patrikmarky said:

Yes speakons ..it’s now going back to be looked at ..had no clipping I always watch that as been burnt by that before ..one thing I’d did notice was the fan runs constantly not sure if that should be the case on these older class A amps my GK legacy only comes on when needed ..

It's not a class A amp, therefore you can rule that out.

 

Some amps have the fans running continuously, some fan's speed track the temperature of a specific component or section, and some fans run intermittently. It depends on the specific design.

 

Sounds like it needs to be serviced by a qualified service tech.

[Downunderwonder]

I would have assumed 2-8 meant two 8 ohm cabs could be connected.

[warwickhunt]

2 hours ago, Downunderwonder said:

I would have assumed 2-8 meant two 8 ohm cabs could be connected.

 

I own one of these and it does indeed mean the amp will operate 'between' 2 and 8 ohms.  

[Downunderwonder]

5 minutes ago, warwickhunt said:

 

I own one of these and it does indeed mean the amp will operate 'between' 2 and 8 ohms.  

Why would it not operate at 12 or 16ohm though?

[warwickhunt]

3 minutes ago, Downunderwonder said:

Why would it not operate at 12 or 16ohm though?

 

It does and I suppose they could have put 2 - 16/32/64/Infinity... but I assume that they have to put on the operating range that 'most' bass players will use and that would be 2 - 8 ohms, I've certainly not used a 16 ohm cab in maybe 35-40 years!  

[patrikmarky]

10 hours ago, agedhorse said:

It's not a class A amp, therefore you can rule that out.

 

Some amps have the fans running continuously, some fan's speed track the temperature of a specific component or section, and some fans run intermittently. It depends on the specific design.

 

Sounds like it needs to be serviced by a qualified service tech.

EBS HD350 is equipped with stacks of extras that include a compressor/limiter, tube and speaker simulator, bright filter, overdrive stage in pure “class A” and a powerful accelerated MOSFET power amp with a high efficiency cooling system. All this is housed in a reinforced 2U rack-spaced steel chassis, weighing in at less than 9 kg / 20 lbs.”

Other specifications include:

Input Impedance 1 ohms

Frequency Response 35″ 20.000 Hz

Maximum Compression Ratio (Compressor) 3:1

Tone Controls Bass/- 15 dB @ 100 Hz

20 dB @ 10 kHz

Drive Control Gain 0-30 dB

Drive Type Solid State

Effects loop and Balanced Output

Minimum speaker impedance 2 ohms

Dynamic Output Power 350 W RMS

Continuous Output Power 300 W RMS

Middle +/-12 dB @ 50 – 3000 Hz, Q=0.5

Treble +/- 15 dB @ 4 kHz

Bright -0/20
 

my reason for thinking it’s a Class A ?…

[agedhorse]

On 16/07/2024 at 02:57, patrikmarky said:

EBS HD350 is equipped with stacks of extras that include a compressor/limiter, tube and speaker simulator, bright filter, overdrive stage in pure “class A” and a powerful accelerated MOSFET power amp with a high efficiency cooling system. All this is housed in a reinforced 2U rack-spaced steel chassis, weighing in at less than 9 kg / 20 lbs.”

Other specifications include:

Input Impedance 1 ohms

Frequency Response 35″ 20.000 Hz

Maximum Compression Ratio (Compressor) 3:1

Tone Controls Bass/- 15 dB @ 100 Hz

20 dB @ 10 kHz

Drive Control Gain 0-30 dB

Drive Type Solid State

Effects loop and Balanced Output

Minimum speaker impedance 2 ohms

Dynamic Output Power 350 W RMS

Continuous Output Power 300 W RMS

Middle +/-12 dB @ 50 – 3000 Hz, Q=0.5

Treble +/- 15 dB @ 4 kHz

Bright -0/20
 

my reason for thinking it’s a Class A ?…

Except for the fact that it's a class AB power amp.

 

The class A description is with regards to a specific preamp gain stage.

[patrikmarky]

So it’s a Class AB amplifiers even better

then ..😃 doesn’t that mean it’s got higher efficiency than Class A amps ..and less distortion than class B amplifiers.?

[agedhorse]

7 hours ago, patrikmarky said:

So it’s a Class AB amplifiers even better

then ..😃 doesn’t that mean it’s got higher efficiency than Class A amps ..and less distortion than class B amplifiers.?

If you believe all the marketing crap, sure.

 

There are plenty of examples of class B amps that have less distortion than class AB amps, but it's also part of the definition of class B which in practice is impossible to attain, therefore all class B amps are technically either class C (slightly less than 180 degrees conduction angle) or class AB greater than 180 degrees). To achieve exactly 180 degrees is like balancing a marble on the top of a ball. 

 

Class AB, B and C are all greater efficiency though, and class C can be rather dreadful at low volumes in particular.

[rwillett]

I've read it once I read it twice, then I read it backwards, forwards again, I looked at with glasses and then took them off and squinted, but I am still no wiser apart from the bit about "balancing a marble on the top of a ball"

 

I suspect this is what people may think about me when I talk about network designs and protocols

 

I believe this is all very knowledgable and learned... My electric theory stops at 5V, a tiny amount of current, and a leading or trailing edge squarish wave for serial comms. Anything beyond that is black magic.

 

I will follow this thread on the off chance a simple crumb of information will fall off the table that I understand...

 

Rob

 

 

Edited July 18 by rwillett

[agedhorse]

3 hours ago, rwillett said:

I've read it once I read it twice, then I read it backwards, forwards again, I looked at with glasses and then took them off and squinted, but I am still no wiser apart from the bit about "balancing a marble on the top of a ball"

 

I suspect this is what people may think about me when I talk about network designs and protocols

 

I believe this is all very knowledgable and learned... My electric theory stops at 5V, a tiny amount of current, and a leading or trailing edge squarish wave for serial comms. Anything beyond that is black magic.

 

I will follow this thread on the off chance a simple crumb of information will fall off the table that I understand...

 

Rob

 

 

It's an astable equilibrium, doesn't take much to push it out of equilibrium which is why class AB was used... it forces the issue to the better side of the compromise.