Using Mono Blocks

detlef

Hi,
I am new to the forum and need a little help. Just finished rebuilding a pair of 2.3tl including the crossovers. I am driving them with two Mcintosh MC2205 amps rated at 200watts RMS per channel and noticed that I am running little bit out of power. I could bridge them to 400watts RMS but have to use a isolating transformer. I was reading The AI-1 Dreadnought Project Pt.1 from Member DarqueKnight many times and I would like to build my own. I am not a electronic guy but can follow instructions very well. Based on his pictures I could build it but it does not tell were the the wire from the Amps go. I don't want to blow something up.

Right Pin = Red/Yellow

Right Blade (Negative Speaker Terminal) = Black/Orange

Left Pin = Grey/Brown

Left Blade (Negative Speaker Terminal) = Blue/Violet

Here comes my I think stupid question. The Right and Left Interconnect Blades are not used and the amps are hooked up as usual? Positive to positive and negative to negative?
Also. Could the transformer he used handle a 1000 watt Amp?
Any help would be great and appreciated.

Thanks,
Detlef

thsmith

AMP leads go to speaker directly.

The blade connections go to the negative terminal of your speakers.

drumminman

Here comes my I think stupid question. The Right and Left Interconnect Blades are not used and the amps are hooked up as usual? Positive to positive and negative to negative?
Also. Could the transformer he used handle a 1000 watt Amp?
Any help would be great and appreciated.

The AI-1 Dreadnought is used with the IC cable that connects the speakers to each other, not with the amps. The way the amps are connected is not affected, unless you have strapped the negative teminals together. This becomes no longer necessary with the DN mod.

The pin of the IC cable connects to a positive terminal on the DN, and the other lead on the IC cable connects to the negative speaker binding post and the negative DN binding post. If the speaker binding posts are not strapped together (IOW if you're biwiring), connect to the lower negative binding post. If they are connected it probably doesn't matter so much whether you use the upper or lower.

Many people disconnect the pin blade socket and install another binding post when doing this mod. That way you can use high grade speaker cable with spades or banana terminations in place of the somewhat cheesy factory cable.

Good luck and welcome to CP!

fjross

I am new to this site and maybe some others with a great deal of knowledge can chime in. Are you currently running in a mono block configuration with two amps? I just recently spoke to AC regarding running either two MC352's or a pair of MC501's and I believe that they are not comon ground in this configuration. If I understood them correctly, I thought they said that they couldn't be strapped either. I maybe looking to either build or buy an A-1 in the near future if I decide to go down the mono block route. . I'm not sure about your MC2205.

detlef

Thanks for all your help so far. I am running the MC2205 in stereo mode. On for the high and one for the low section. They are not common ground amps.

Thanks

drumminman

detlef wrote: »

Thanks for all your help so far. I am running the MC2205 in stereo mode. On for the high and one for the low section. They are not common ground amps.

Thanks

I wouldn't do that. You can damage the amps, the speakers or both with the IC cable connected. Not a problem if you disconnect the IC cable, but then you lose the SDA effect. Do a search here on the forum for more info.

fjross

drumminman wrote: »

I wouldn't do that. You can damage the amps, the speakers or both with the IC cable connected. Not a problem if you disconnect the IC cable, but then you lose the SDA effect. Do a search here on the forum for more info.

That's the road I was heading down.

detlef

What you saying is, I cannot bi-amp the speakers when using the interconnect cable?

quadzilla

If you run each amp in stereo, then you should be fine. If you run them as monoblocks, you'll have a problem if you don't use the AI-1 SDA cable.

heiney9

detlef wrote: »

Thanks for all your help so far. I am running the MC2205 in stereo mode. On for the high and one for the low section. They are not common ground amps.

Thanks

quadzilla wrote: »

If you run each amp in stereo, then you should be fine. If you run them as monoblocks, you'll have a problem if you don't use the AI-1 SDA cable.

Re-read his post. He said the amps run in stereo are NOT common ground.

quadzilla

yeah, didn't read the whole thread. But aren't the MC2205s common ground? Even if not, in stereo, you can strap the commons to make them common ground.

detlef

I think I got it now. I build the interface and connect the left positive to the round pin where the interface cable use to go . The left negative goes to the left ground binding post. Then I will bridge my amps to mono and connect them as usual. Now I have more power available and I should be fine. Is this it?
Correct me if I am wrong.

detlef

You cannot run them in mono and connect both chassis together according to McIntosh. You will blow them up.

heiney9

quadzilla wrote: »

Even if not, in stereo, you can strap the commons to make them common ground.

You know that for a fact or just guessing. Not all non-common ground amps can be strapped.

detlef

heiney9 wrote: »

You know that for a fact or just guessing. Not all non-common ground amps can be strapped.

I have called Mcintosh

DarqueKnight

detlef wrote: »

Could the transformer he used handle a 1000 watt Amp?

It appears that all of your concerns have been addressed except this one.

Yes, the Avel Lindberg Y236906 transformer can handle a 1000 watt amp. The Y236906 is rated for 800 VA (volt-amperes). For a typical amplifier power factor (pf) of 0.65, the real, or active, power rating in watts is

Pwatts= Pva x pf ===> 800 x 0.65 = 520 watts.

The SDA signal is 1/2 the power of the stereo signal. Therefore, a stereo signal of 1000 watts would present an SDA signal of 500 watts. This is below the Y236066's 520 watt power rating with a 0.65 pf amplifier.

heiney9

detlef wrote: »

You cannot run them in mono and connect both chassis together according to McIntosh. You will blow them up.

quadzilla wrote: »

Even if not, in stereo, you can strap the commons to make them common ground.

You both are talking about different things.

I have to say this is the most confusing thread about common ground I have ever read. Sheeeesh.......there isn't a single straight answer to a single question. It's all over the place like a true schizophrenic would answer.

There are about 4 sub questions going on here and not a single one has been answered with any clarity.

Mono amps, whether brigded stereo or single mono block can NOT be used with SDA's because by their very nature of design are NOT common ground.

A stereo amp running in stereo can be common ground or non-common ground depending on the design of the amp. If a STEREO amp (running in stereo) is NON common ground it can't be used with SDA's

The above two senarios are assuming one is using the standard interconnect cable.

Some non common ground STEREO amps (again running in stereo) can have their negative speakers terminals strapped to make it a common ground, some can NOT.

Certain model SDA's can use an AI-1 interconnect which uses an isolation transformer for non common ground amps being stereo or mono.

H9

FTGV

Mono amps, whether brigded stereo or single mono block can NOT be used with SDA's because by their very nature of design are NOT common ground.

Not to confuse things further but some dedicated mono bloc's can have there negative terminals strapped.It depends upon the configuration of their specific output stages.

detlef

DarqueKnight wrote: »

It appears that all of your concerns have been addressed except this one.

Yes, the Avel Lindberg Y236906 transformer can handle a 1000 watt amp. The Y236906 is rated for 800 VA (volt-amperes). For a typical amplifier power factor (pf) of 0.65, the real, or active, power rating in watts is

Pwatts= Pva x pf ===> 800 x 0.65 = 520 watts.

The SDA signal is 1/2 the power of the stereo signal. Therefore, a stereo signal of 1000 watts would present an SDA signal of 500 watts. This is below the Y236066's 520 watt power rating with a 0.65 pf amplifier.

Thanks for your input and thanks for confusing me with facts:-)
Let me ask you a simple question. I want to buy two MC1000 mono blocks to drive the 2.3tl and maybe a pair of 1.2. Will the work with your design?
As I stated before I am not a pro with this stuff. I was just exploring an option to use NON COMMON GROUND amps with the polks. At this point I will consider selling everything I have and buy some simple speakers from RadioTrash:-)

heiney9

FTGV wrote: »

Not to confuse things further but some dedicated mono bloc's can have there negative terminals strapped.It depends upon the configuration of their specific output stages.

Thanks for adding that, I missed that in my post. The Adcom 565 mono bloc's being one example.

F1nut

detlef wrote: »

Hi,
I am new to the forum and need a little help. Just finished rebuilding a pair of 2.3tl including the crossovers. I am driving them with two Mcintosh MC2205 amps rated at 200watts RMS per channel and noticed that I am running little bit out of power. I could bridge them to 400watts RMS but have to use a isolating transformer.

There's a problem with your idea. Bridged amps do not like to see less than an 8 ohm nominal load. Your SDA's are 6 ohm nominal and dip lower. Bridged amps also have higher distortion levels.

You should also realize the maximum SPL difference between 200 and 400 wpc is minimal. At best you'll gain a few dB.

W=dB
1=90
2=93
4=96
8=99
16=102
32=105
64=108
132=111
264=114
528=117

quadzilla

I meant run them stereo and strap the one common on amp a to the other common on amp a. Then using the left signal into the left input of both amps with a splitter, and the right into the right with a splitter. What's Mac say about that?

DarqueKnight

detlef wrote: »

Thanks for your input and thanks for confusing me with facts:-)
Let me ask you a simple question. I want to buy two MC1000 mono blocks to drive the 2.3tl and maybe a pair of 1.2. Will the work with your design?

I can't answer this because I do not know the performance specs of the MC1000 (e.g. power factor and output power at various speaker loads). Once you obtain these specs you can calculate the Dreadnought's performance boundaries using the example I gave above.

DarqueKnight

detlef wrote: »

Also. Could the transformer he used handle a 1000 watt Amp?

Thinking further about your question I see that there is some inaccuracy in my answer in post #16.

Here, as in the previous answer, I will neglect the small amount of power going to the tweeters. With an assumed amplifier power factor of 0.65, and the 2:1 split of amplifier power between the stereo and dimensional drivers (dimensional drivers produce 1/2 the output of the stereo drivers), a 1000 watt signal would have:

1. Two thirds power going to the stereo drivers (666.67 watts).
2. One thirds power going to the dimensional drivers (333.33 watts).
3. The apparent power, in VA (volt-amps), in the dimensional circuit would be watts/pf = VA ====> 333.33/0.65 = 512.81 VA. This is well below the 800VA rating of the Y236906 transformer.