what factors will give iron fist bass?

[planet10]

Originally Posted by BudP

Gary Pimm uses a Crown DC 300

How stock is it?

dave

[BudP]

Oh, well there's a question init?

Bud

[planet10]

Originally Posted by BudP

Oh, well there's a question init?

Bud

Indeed.

0/ DC300 run full range is an awful amplifier
1/ when has Gary ever not gone in and added his own magic?

dave

[BudP]

Yes, doubtless #1 or even #2 left unspoken, but it LOOKED stock. Only ran up to about 100 Hz for the subs. His all SS push pull Tabor with input splitter, interstage and output transformers involved, drives the mids and highs. After EnABL he dropped one of the Beta 8 drivers as redundant. A large, ribbon flat panel, tweeter sits on top of the U baffle that houses the Beta 8 driver. Not the prettiest system ever seen, but OMG effective.

Bud

[googlyone]

I suspect that a quest to achieve "iron fist bass" through the use of one amplifier in preference to another means that either:
- the quest team have headed off in completely the wrong direction, or
- I have completely misnderstood what you are after.

Iron fisted bass to me is not a nuance, it is the smack around the head and physical kick in the guts that is delivered by a serious sound system capable of live music levels of SPL.

This is not that hard to do but:
- don't pretend that a domestic speaker will do this. In this I include all your vita, scan speak etc drivers
- don't try to do this with anything but an actively crossed system (ok I concede it might be possible full range into a passive crossover but I forecast dead tweeters)
- do consider the use of Pro drivers. Choose them carefully
- do recognise the need for balanced mid bass with sub.

This last bit is critical. All the sub in the world sounds crap if not balanced with midbass - especially in the 60-200hz region.

Don't get me wrong. I have a lot of (what may now be ageing) good quality domestic drivers, and in the "moderate" SPL domain they are brilliant.

The problem is that if you want to produce the viserial thrill of that hit on the drum or snapping bass line that cracks you around the ears and twists your guts, then you need the capacity to generate some serious short term SPL.

This is not what domestic drivers are made to do.

Do the math on a fairly efficient domestic driver and you will almost always find that short of overdriving it you cannot hope for more than 105 odd dB. This usually ignores compression and issues with excursion. If you try this on a full range amplifier it also ignores clipping and what this does to your tweeter.

If you are really after iron fisted bass I suggest you rethink the vifas and keep them in the same special place I do (for moderate listening where they really do shine).

If this is about something intangible that one amplifier will fix over another then I politely excuse myself lest I become heretical.

To me the basics are:
- active crossover. Minimum 2 way but prefer 3 way. Get the sub off the bassmid and highs
- a good high efficiency sub.
- 30 hz and up is a minimum. Go for something that can deliver toward 120 dB. This will however deliver all but the most extremely processed music. Below 30 hz is an option for those with lots of space.
- get some excellent bassmid and high drivers. These need to be capable of similar peaks, and be appropriately matched to the subs If you fail here the bass will sound crap.
- the crossover and matching is pretty important. I have done this in analogue active but I promise that a digital crossover will make this a whole lot easier.

Things this does:
- the drivers will be capable of 10 or more dB SPL
- the crossover will allow the amplifiers to drive only the voltage required in their band. If this sounds obtuse read up on active crossovers and why you would want one.
- the use of an active system means that if you do clip the subs a bit, this does not affect the midbass and highs. This is a super super important difference.

That extra 10 or 15 dB that this delivers makes a difference that is profound.

The clarity of sound you will achieve at solid SPL levels is surprising.

Phil

[Keith Taylor]

I find it hard to sit idly by when damping factor is being discussed with the brain in neutral! If we confine ourselves to the real part of complex impedances, damping factor is the ratio of the load resistance to the driving source resistance.

True believers in high damping factors seem to concede that the wiring resistance can degrade the situation and often have cables that could be used for arc welding.

What gets overlooked is that the voice coil resistance is also in the series loop. This means that the damping properties have already been defined by this dominant resistance, so it is pointless trying to remove the last few milliohms in the driving source (amplifier) or the cables.

I notice that Rod Elliott, who is a great debunker of audio myths has yet to latch on to this reality. Having said that I concede that I did learn from him that passive crossovers cause a loss of driver damping control at the band limits due to parallel resonant circuits in the driving loop. A good reason to avoid them.

Keith

[a.wayne]

This is becoming a funny thread , the OP ask what gives you tight bass from an amplifier , what does speaker brand , topology or xover used have to do with his amplifier question ...

[a.wayne]

Originally Posted by Keith Taylor

I find it hard to sit idly by when damping factor is being discussed with the brain in neutral! If we confine ourselves to the real part of complex impedances, damping factor is the ratio of the load resistance to the driving source resistance.

True believers in high damping factors seem to concede that the wiring resistance can degrade the situation and often have cables that could be used for arc welding.

What gets overlooked is that the voice coil resistance is also in the series loop. This means that the damping properties have already been defined by this dominant resistance, so it is pointless trying to remove the last few milliohms in the driving source (amplifier) or the cables.

I notice that Rod Elliott, who is a great debunker of audio myths has yet to latch on to this reality. Having said that I concede that I did learn from him that passive crossovers cause a loss of driver damping control at the band limits due to parallel resonant circuits in the driving loop. A good reason to avoid them.

Keith

Yet full passive systems outstretch their full active counterparts by a country mile ..

[TerryO]

Originally Posted by a.wayne

This is becoming a funny thread , the OP ask what gives you tight bass from an amplifier , what does speaker brand , topology or xover used have to do with his amplifier question ...

I'm sure I'm guilty of this as well!
So, to make amends, here's a posting from last November made on another forum.

(I wrote: )

Damping Factor is a term that by it's designation seems to suggest all sorts of things that, actually aren't involved. As a figure of merit it's nearly worthless and is more of an incidental by-product of negative feedback than being any sort of positive design feature. Here's what (I believe) gives some real insight into the realm of what those high damping factors actually mean in the real world.

AK's Dave Newman (dnewma04) wrote:


"Let's do some math.

We know that damping factor is a ratio, specifically, it's the load impedance divided by the output impedance of the amplifier. For now, we'll ignore how amplifiers attain low output impedance just for the sake of simplicity.

So, let's say we have an amplifier with a damping factor of 2000 and an impedance of 8 ohms.

DF = Load Impedance / Output Impedance

2000 = 8 / Output Impedance

Output Impedance = .004

All is well in the world, right? We have our staggeringly high damping factor but we've ignored something important.

We forgot to include the series resistance of the speaker wire between the amp and speakers. Let's redo the calculation now.

Again, we know that DF = Load Impedance / Output Impedance, but now we are going to add in the effects of the speaker wire into our equation to figure out what the "real" or "effective" damping factor is of the real world situation. For simplicity sake, we'll err on the side of caution and say that it's very low resistance wire and only presents a .1 ohm load.

DF = 8 ohm / (.004 ohm + .100 ohm)
DF= 8 ohm / .104
DF= 76.9

The advertised damping factor of 2000 is now only 77 at the terminals of the speakers.

Now, let's look at what is going on at the terminals of the woofer in a speaker system with a passive crossover.

It's not unusual to have a series resistance of 1 ohm in a passive crossover, but just for a best case scenario, let's say that it's only .25 ohm.

DF = 8 / (.004 + .100 + .250)
DF = 8 / (.354)
DF = 22.6 at the woofer.

Now, let's say the damping factor of the amp is 20000! Surely that must make a huge difference being an order of magnitude higher than 2000!

Unfortunately, the reality is:

DF = 8 / (.0004 + .25 + .1)
DF = 22.8

It's essentially the same.

Now, let's say that the amplifier in the same scenario is only at 50.

DF = 8 / Output impedance

50 = 8 / Output Impedance

Output Impedance = .16

Now that we have the output impedance of the amp with a DF of 50, let's substitute into our scenario to see the DF at the woofer:

DF = 8 / (.16 + 1 + .25)
DF = 8 / (.51)
DF = 15.7



Do you see how most people just don't find DF that important? In the real world, the difference between a low DF amp and a ridiculously high DF amp is essentially moot at the woofer."

Best Regards,
TerryO

[TerryO]

The topic's title reminded me of the famous quotation from a speech made by Prussia's Otto von Bismark in the 1860's:

Not by speeches and decisions of majorities will the greatest problems of the time be decided - that was the mistake of 1848-49 - but by iron and blood.