Modifying a Trace Elliot 2x10...

[danlea]

Hey fellas,

As my signature says, I have a Trace Elliot head with two channels that each deliver 300W into 4 ohms. I have a 2x10 at 4 ohms (8 ohm 100W drivers because they don't sell the 16 ohm ones any more) and an 8 ohm 1x18 (soon to be a Trace Elliot one rather than the home-brew). Now I'm not going to go about looking for a 4 ohm 18" speaker to max out that channel as these seem to be extremely rare beasts and of course 18s are expensive, however I was pondering what I could do with the 2x10 to make good use of the power amp both in rehearsals (1x18 + 2x10) and at gigs where I can just take the 2x10.

To get to the point, my idea is to buy a couple of higher-powered 10s from [url="http://www.lean-business.co.uk/eshop/index.php?main_page=index&cPath=20"]here[/url] and separate the input and link jacks, one for each driver. This means I would be able to have 400W from my 2x10 running both channels into 8 ohms - perfect for being able to hear myself on stage (the lows will be flooding the entire venue from the FOH anyway, but I'd still like to have as beefy a sound from the cab as possible). Then when I'm back rehearsing and need the 1x18 to get the full range sound I can use a 1/4" jack splitter (I realise I'd probably need to make one using proper speaker cable rather than using a standard Maplins one) to put the 10s in parallel and run that channel at 4 ohms (then only putting 300W into it, but that's fine).

Now I have three questions:

1) Does anyone expect that all that power (400W) going into a 2x10 designed for 200W would cause a problem?
2) Would the green label celestions be a bad idea due to the weightier bass? I've emailed Celestion asking what the frequency response of the Trace Elliot custom speakers is so I can compare to the green and orange label celestions.
3) Is it just a bit stupid to think that 400W coming from two 10" speakers is going to give a much louder sound than 200W coming from the same configuration, albeit the replacement speakers being capable of handling more bass in particular? I don't know the SPL of the TE speakers, but the replacements would be 96dB (green) or 98dB (orange) (see spec [url="http://professional.celestion.com/bass/"]here[/url]).

That is all.

Dan.

Edited August 9, 2008 by danlea

[alexclaber]

Don't do it. Switching to speakers with a higher thermal power rating does not mean they can actually handle the extra power (because their mechanical power handling is likely to be too low). The difference between 300W and 400W from your amp is negligible. Frequency response and SPL specs mean very little - you need to model the T/S parameters to find the true low frequency response and sensitivity. In other words:

1) Not a problem but it won't really be any better than 300W into the same cab.
2) Until Celestion release full T/S parameters then IMO they're all a bad idea.
3) Yes. You don't know if the replacements will be able to handle more bass - see previous answer.

Alex

[Lfalex v1.1]

As AC says, probably not worth it.
The T/S parameters he refers to are Thiele/Small parameters, and these describe just about every physical and electrical detail of the driver in question.
These can then be used to calculate optimum enclosure dimensions to give the desired sonic performance (see also Hoffman's Iron Law) using either good, old-fashioned equations or a PC based application such as Win ISD.
Unfortunately, far too many driver manufacturers are a more than a little coy about releasing some of these details, which makes simply replacing drivers with other ones that fit the holes in a cabinet baffle something of a lottery at best!

As an aside, The older 2103(and H) [i]definitely[/i] had 16ohm drivers in, wired in parallel to give a cabinet load of around 8ohms.
I (ahem) cut the amp stage out of my H122SMX and fashioned a (slimmer) 2103h of sorts and a separate head, primarily for convenience. That also has 16ohm drivers in.
I own a 1048h from the same era, but I don't know if that's 4x32ohm drivers in parallel or something else entirely!

[danlea]

Thanks for the input guys. I know the older 2x10s had 16 ohm drivers because one became faulty and I made the mistake of going to Andy's Repairs on Denmark Street to get replacements because I couldn't find exact replacements myself. He then went and bought the only Trace Elliot tens celestion now make, from a US catalogue! Ended up costing me over £60 each, and they were 8 ohms, not 16! I could've just gotten them from Watford valves for half the price.

Alex, with the replacement idea I was working on the basis that the frequency response of the replacements does extend down to 40/45Hz (not sure what dynamic range that specifies) and that the TE speakers are more likely to be similar to the orange labels (down to around 70Hz), given the sound of the cabinet - obviously can't be sure about this though, so yeah, too many unanswered questions really. Also the current speakers (and the originals) are only 100W each, so the power difference would be a factor of two, rather than four thirds (which I'm certain would be pointless).

Anyway, consider me warned off the change.

[alexclaber]

[quote name='danlea' post='259953' date='Aug 11 2008, 01:48 PM']Alex, with the replacement idea I was working on the basis that the frequency response of the replacements does extend down to 40/45Hz (not sure what dynamic range that specifies) and that the TE speakers are more likely to be similar to the orange labels (down to around 70Hz), given the sound of the cabinet - obviously can't be sure about this though, so yeah, too many unanswered questions really.[/quote]

You don't know what the actual frequency response is without modelling the drivers - most are squeezed into too little cab volume thus losing potential extension.

[quote name='danlea' post='259953' date='Aug 11 2008, 01:48 PM']Also the current speakers (and the originals) are only 100W each, so the power difference would be a factor of two, rather than four thirds (which I'm certain would be pointless).[/quote]

No it wouldn't because the power difference that matters is the amp output (which is simply down to impedance) not the thermal power handling. Remember, speakers don't produce power output, they consume power input.

Alex

[danlea]

[quote name='alexclaber' post='259974' date='Aug 11 2008, 02:20 PM']No it wouldn't because the power difference that matters is the amp output (which is simply down to impedance) not the thermal power handling. Remember, speakers don't produce power output, they consume power input.[/quote]

Well I suppose the power handling is largely irrelevant given that what I'm looking for is better handling of low frequencies (so a larger xmax, etc.) rather than the overall power dissipation. I was just working under the assumption that an equal sensitivity meant equal efficiency (even at low frequencies) and that this would remain constant with increased power ratings. Not the best idea evidently.

Dan.

Edited August 11, 2008 by danlea