bedrock 1000 series head -> two cabinets possible ?

trasher · Joined: 13 Apr 2005 Posts: 7

hi guys,
i have a problem with my bedrock head.

its a 1000 series head 100 W and i got a 4 ohm and a 8 ohm outputjack for the cabinets.
there´s "minimum total impedance must be 4 ohm !" written under hte jacks.

now the problem, what if i wanna use a fullstack ?

i don´t knom how to put in the cables, and i´m a little confused if it´s even possible zo us two cabintes with this head ?

maybe someone can help me ?
sorry for my english, but i´m german, and school is a long time over Very Happy

!

lee_UK · Posted: Wed Apr 13, 2005 11:29 pm Post subject:

You need to get 2 stacks of the same total impedance, if you already have a 4x12 cab and its rated at 16ohms then you need another of that impedance link the together in paralell (cab1 output jack - to cab 2 input jack ) then take a cable from the input jack of cab 1 to the 8 ohm output jack of your amp.

if however you have a 4x12 rated at 8ohms, then you need another 4x12 of the same rating, link them in the same order as above but connect the input jack of cab 1 to the 4ohm output jack of your amp.

Apeice of advice, a lot of people use patch leads and guitar leads to link their cabs to the output jacks of their cabs, when in fact you need good quality speaker cable, like you use for your speakers at home, a good multistranded
OFC copper cable would be good to use, the inner core of a lot of guitar cable is a thin strand of copper and isnt up to the job, sound quality and reliabilty is greatly improved, would you risk a speaker cable breakdown in the middle of a set? and if you are running a nice expensive valve amp think of the damage that could cause.

1bassleft · Posted: Fri Apr 15, 2005 12:37 am Post subject:

Trasher, no need to apologize for the English. Faultless, certainly better than my German.

Lee is, as often, right. Chain two 16ohm cabs together and connect this to the 8ohm output. Or, chain two 8ohm cabs and connect to the 4ohm output.

Lee makes the excellent point that speaker cable is not the same as instrument to amp cable. I've never mentioned this before. Apart from the point Lee makes, an instrument cable is shielded. On a long cable, this will affect the impedance the amp "sees" and there may be a mismatch. Quality amp to speaker cable will be unshielded and have heavier duty 'hot' wire to carry the amplified signal. Keep it as short as you can live with. If the head is on top of the stack, 6m is a waste and has bad effects. 1m is preferable.

trasher · Joined: 13 Apr 2005 Posts: 7

thanx boys, but ho do i connect two cabs ?
i have a jcm slash cab 4x12", and it has a 4 ohm and a 16 ohm input for mono and you can switch them to 8 ohm stereo, so how can i connect this cab with for example the same type of cab ?

lee_UK · Posted: Fri Apr 15, 2005 3:25 pm Post subject:

1bassleft wrote:

On a long cable, this will affect the impedance the amp "sees" and there may be a mismatch.

Good call on that one bass, i forgot about about the extra impedence the long copper cable makes.

1bassleft · Posted: Wed Apr 20, 2005 12:24 am Post subject:

Trasher, just in case your 'notify me' is switched on, I did a new topic called "some impedance theory", as others have put similar Qs. There has since been another thread on the subj from Riz you may want to read.

I hope something posted here is useful.

trasher · Joined: 13 Apr 2005 Posts: 7

thanks, i solved the problem, the two jacks are wired parallel, so i can use 4 ohm, 2 x 8 ohm, or 2 x 16 ohm, cause the amp needs 4 ohm minimum impedance. the amp didn´t care about the rest, as long as the impedance dos not drop below 4 ohm.
btw, does anyone of you have the manual for the bedrock 1000 series ? can´t find one here in germany, or even in the web !

lee_UK · Posted: Thu May 05, 2005 12:32 am Post subject:

Trasher, just make sure you are 100% before you start, it could be an expensive mod. Double check your info.

1bassleft · Posted: Fri May 06, 2005 12:42 am Post subject:

Trasher, first of all, try a good search engine. Copernic is a favourite of mine - a free download. You will find Bedrock amp hits such as a Bedrock forum on Bravenet.com

Secondly, I echo Lee's caution. Do you mean that your amp's output jacks are wired in parallel? They certainly will be. If they were wired in series, then you'd have no volume out unless they were all connected. I suggest that you daisy-chain your cabs, then connect cab #1 to the most appropriate output jack on your amp.

It may be boring, but please read my dull thread on "impedance theory" posted on this forum. Also, check the link to David Zsabados' website contained within. Some of this reading can save you from an expensive mistake.

trasher · Joined: 13 Apr 2005 Posts: 7

i took it to a tech, he checked it and said that to me. i tested it and it works. i also combined an 8 ohm cab and my 4 ohm cab and it works without problems.

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