Opinions on Transcendent SE-OTL's (bridged) verses McIntosh MC-30's

[Coytee]

"If the outputs of the Peach are too high, it tends

to knock the dbx down. If they're backed off, then it seems to be much

more behaved."

I'd think either the pre-amp is spitting out DC (isn't the DBX Direct

coupled?) or it might be too hot.

"I'm cutting everything back on the very amp I'm trying to use to crank

it up with. Kind of self defeating."

Turning the level controls down does not in any way shape or form limit

the power available from the amp. You keep getting stuck on that.

Shawn

My take on it is, if the inputs on the dbx are set at say, 50% AND if

the Peach's outputs are set at say 50% (to help eliminate cutting out

by the dbx), then I don't have as much headroom there as contrasted if

I was able to keep BOTH units set at say, 100%. (I realize I

still might not be fully understanding it)

If I'm in the room listening, it doesn't matter that I have both tamed

down because I'm not out to cause ear bleed. However, when I'm

downstairs working, I DO turn it up to ear bleed levels so that I can

hear it easily downstairs.

Oh well... most of this is probably a moot point since the MC-2102 will

arrive Monday or Tuesday. If push comes to shove, I might even

get the C-2200 (??) preamp for the 2102 and see how it does in contrast

with the Peach. This way I can then look into the balanced cables

too. (I think the 2200 was designed with the 2000 and 2102 in

mind?)

If Terry hadn't given the dbx a clean bill of health, I'd be fairly

sure something was amiss inside it. Given all is as it should be,

and how behaved the Peach was with my Jolida 502 and OTL's, I can only

surmise that somehow or another the Peach & dbx don't get along too

well together.

I'm sure that NO ONE would ever think that I was perhaps pushing things a bit too hard... [6]

[NOSValves]

"If the outputs of the Peach are too high, it tends to knock the dbx down. If they're backed off, then it seems to be much more behaved." I'd think either the pre-amp is spitting out DC (isn't the DBX Direct coupled?) or it might be too hot. "I'm cutting everything back on the very amp I'm trying to use to crank it up with. Kind of self defeating." Turning the level controls down does not in any way shape or form limit the power available from the amp. You keep getting stuck on that. Shawn

My take on it is, if the inputs on the dbx are set at say, 50% AND if the Peach's outputs are set at say 50% (to help eliminate cutting out by the dbx), then I don't have as much headroom there as contrasted if I was able to keep BOTH units set at say, 100%. (I realize I still might not be fully understanding it)

You indeed have it all wrong. This is system mating. The amp can still make 100% of its power with its levels set at 75%, 50% or even 10% it will just require more input from the preamp to reach 100% output. The level control on both products are they to get them the act proper. Play with them a while, get them where you like them then forget them.

[sfogg]

"Given all is as it should be, and how behaved the Peach was with my Jolida 502 and OTL's, I can only surmise that somehow or another the Peach & dbx don't get along too well together."

Neither of those amps are DC coupled with a DC servo and protection circuits on the outputs. The DBX is.

If you have a multi-meter try hooking it up to the Peach and see if perhaps it (or a source ahead of it if it is DC coupled) is putting out some DC.

Shawn

[Coytee]

"Given all is as it should be, and how behaved the Peach was with my Jolida 502 and OTL's, I can only surmise that somehow or another the Peach & dbx don't get along too well together." Neither of those amps are DC coupled with a DC servo and protection circuits on the outputs. The DBX is. If you have a multi-meter try hooking it up to the Peach and see if perhaps it (or a source ahead of it if it is DC coupled) is putting out some DC. Shawn

OK, now we're getting somewhere... but another wall of ignorance.

I DO have a multi meter. I am not well versed in it other than most basic "is this outlet going to zap me"

Might I presume I click it over to dc, set it up for (how many) volt reading and then just simply touch it to the outputs of the Peach?

If there is ZERO dc output, I'd get a zero reading and all is implicetly well??? If it bumped at ALL (stricktly speaking), then I might have an issue? Is there a range of acceptablity?

Sorry for more quesitons but THIS endeavour, I CAN do... I just need a bit of guidance on specifics.

[sfogg]

"Might I presume I click it over to dc, set it up for (how many) volt

reading and then just simply touch it to the outputs of the Peach?"

Basically, set the Peach up like how you normally listen at a level that causes the DBX to cut out.

Then shut off the Peach (without changing inputs or adjusting the

volume) and the DBX and unplug the cables from the output on the Peach.

Set the multimeter to DC and set it to as low of a level as it can go.

Turn the Peach back on and after it warms up put the positive lead on

the multimeter inside one of the outputs of the Peach with it touch the

inner wall of the RCA and touch the negative lead to the outside of the

output connector. See if you read any DC.

The other way to do it is to instead unplug the cable from the amp side

(with both pieces off) and touch the positive lead to the pin of the

RCA and the negative to the shield of the RCA on the end of the cable.

Have whatever source you normally listen to playing too.

For a DC coupled amp you basically don't want any DC feeding the amp at

all. If the amp receives any DC it is going to amplify it.

Shawn

[Coytee]

Thank you for the instructions. I'll have to do it tomorrow when I get home.

[NOSValves]

If the Peach is working properly it should have no DC on the outputs. I also believe the test will not work as suggested because the Peach has self shorting RCA jacks. When you pull the IC out the RCA on the Peach shorts the center conductor to ground.

Here is how to test the output. Do as Shawn suggested but instead of pulling the RCA's out of the Peach pull them out of the DBX than test from the outer shell of the RCA to the inner conductor. Do these playing a singnal through the Peach. I believe there should be no DC voltage present. Maybe Mark will see this thread and chime in.

Craig

[NOSValves]

Darn it Mark!! I was trying to get through the entire year without being right once and you had to screw it up for me[]

Craig

PS just tested my Blueberry and it is for all intensive purposes at zero volts on the outputs.

[Coytee]

*Although a few others have said this, I'll repeat it too.

The level controls on either device have nothing at all to do with how much

POWER you can get, or how LOUD you can play the amplifier. Nothing at all to do

with "headroom" or "power" or "loudness" or

speaker volume. You could have the DBX controls set to nearly OFF and still get

Xhundred watts, or how ever many it puts out. Sometimes people think such

controls have something to do with "turning down the power of the

amp." Not so.*

Ok, Im really NOT arguing but I dont get

something here. If the input controls on the dbx are FULL left, I

get zero output, if the controls on the Peach are full left, I get zero

output, so how can "level controls on either device have nothing to do

with how much power I can get out"?

In order for the speakers to play to, lets use 110db for a

reference point, they will need X watts of input.

For the dbx amp to put out that wattage, its input can be

at lets say 50% and the Peach at 50%. The Peachs volume control can also be at 50%. (now we have a general starting point for all

parts of the puzzle)

Heres where Im not getting it...

If the dbx input is reduced to say 25% (to reduce the hiss) and

the Peach stays the same, then the volume control on the peach will have to be

turned up FURTHER to compensate for the reduction in the dbx, to achieve that

same loudness. (fair?)

Now, what if in addition to reducing the dbx to 25%, you

ALSO reduce the Peach to 25% (because of the possible overloading issues on

dbx).

Arent we now having to turn the volume control up even

FURTHER to achieve the same loudness as above, since both variable knobs have

been reduced?

If so... dont we

run out of volume rotation sooner or later?

If the volume control cant turn any further to its right,

if the Peach has its controls toned down to (lets say) 25% (to prevent the dbx from going into protect

mode) and the dbx is toned down to 25% (to reduce that hiss), how can I then

have all the headroom & max volume as suggested?

Ive tried variations of the above and frankly, the loudness coming

through the speakers is more on par with the OTLs and their 4 bridged watts,

rather than the expected assault of 125 watts.

Im not one to argue any of you guys because youve forgotten

more than Ive ever known (or will know), Im just missing something in the

logic.

Again, this is becoming moot because on Monday, the 2102

will arrive and the 30s will arrive on Christmas.

Oh, and I hate burnt eggs

[]

[sfogg]

"If so... dont we run out of volume rotation sooner or later?"

Yes, and that is the only place you might be limiting your volume.

If you don't run out of volume control on your pre-amp you aren't limiting your power at all.

"he loudness coming through the speakers is more on par with the OTLs and their 4 bridged watts, rather than the expected assault of 125 watts."

Uh... the 4 w amp isn't always putting out 4w of power, just like the 125w amp isn't always putting out 125w of power. Those are just the maximum power amounts the amps can put out. How much they are actually putting out depends upon how loud you are listening.

No different then a Corvette C6 that can do 186mph max... it isn't always going 186mph.

"this is becoming moot because on Monday, the 2102 will arrive and the 30s will arrive on Christmas."

May not be moot, you might have the noise problems with them too. The solution isn't to keep buying more amps.....

Shawn

[Coytee]

Hi Mark,

I appreciate the offer and might do it. I want to be sure it's just not me & my ignorance first. I'd hate to waste (even more) of your time with you going through it unnecessarily, than you've already put into it answering here. With that said, PLEASE don't let me forget (in case I DO send it back), I might want to buy one of the walnut cabinets... they look so nice.

Wife works tonight & won't be home. I'll try some of the things mentioned and won't have any issues with her not liking the volume.

as for signal level from source, it's either a Sony cdp or dvd (meaning I have both). I don't THINK there is an adjustable signal on them but I'll look in their back, just in case.

Will report findings (or more questions) later.

[]

[Coytee]

Ok, heres an update: I admit I personally found this interesting. Before I go there, perhaps it would be best to give a verbal diagram of my wiring setup.

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

I have a cd and dvd player both plumbed into the Peach. If it matters (and I doubt it would) they are the far left and far second left clicks on the Peach Selector.

Ok, signal gets into Peach. On the output side, I have Y splitters on each R & L, so I can run one leg of each channel to the Transcendent SE-OTLs and the other leg goes to the dbx amp.

The output of each amp then runs into a Niles a/b switcher and the output of the switcher goes to the Khorns.

Ok, so thats the wiring diagram. Heres what Ive found.

I got my Multimeter out and of course, it had TWO sets of DC. One evidently in dc volts and the other in mVs if I recall correctly.

I surmised that the MV is the setting I wanted to use but I in fact used both so I could rule each one out.

Got the amp to cut out, pulled wires off dbx and put the leads to them I did NOT notice the needle moving at all. I even swapped +/- to be sure I wasnt backwards and nothing ever happened. I did this on both MM settings.

Confused, I hooked it back up and was NOT able to get it to cut out again. Why so? What was different?

The ONLY thing different that Id done was turn the OTLs back on.

Wha?????

Ok, here is what I was able to duplicate at will:

Turned OTLs ON, and was able to CRANK the volume with Peach at full throttle AND the dbx at full throttle, it did NOT cut out.

While it was playing, I switched the OTLs OFF and right at 5 seconds, BAM, the dbx cut out.

Hmm.. ok I took the outputs of the Peach to about ½ (volume still at full), turned the OTLs ON, and was able to crank away. I turned the OTLs off and right AT 5 seconds, the dbx cut out again.

To make a long story short, I fiddled with the Peach controls (dbx inputs still at 100%) and EVERY time I turned the OTLs OFF, the dbx cut out five seconds later. As long as the Otls were left on, everything worked fine.

I then moved to the dbx amp and started to pull those inputs down.

Triple bottom line, the dbx amp FINALLY did not cut out (with OTLs powered down) until I had ITS inputs cut down to around 50% or perhaps less and the OTLs were still at about 50%.

It seems as though turning the OTLs OFF, which I do periodically, is the wildcard. Turn them off, the dbx is hyper sensative, leave them on and everything works as you'd expect it to.

So, with the wiring schematic as stated above, does that shed any light?

I expect an obvious question of, have you totally isolated the dbx and taken the otls out of the circuit and that answer is no, I have not. I might get to that this weekend if time allows. I just found that I could repeat the issue by the simple fact of turning the OTLs off and wanted to share my findings. Actually, I might try to do it right now.

Just so you dont think I messed up and was listening to the OTLs as the power was killed, (crossed my mind more than once because of how consistent it was), I double checked my Niles box AND, took note of the meters dying on the dbx along with one of its lights (above the power button) blinking during this issue.

Sooooooooooooo, any thoughts?

I sure hate to bring you guys easy problems like why won't my amp power up (fuse blown). I like these strange issues!!

[Coytee]

For the record, I apologize for my spacing above. I typed that in Word & copied it over. Those started out as single spaced lines and I don't know why they're so messed up.

Now, with that out of the way, we hit pay dirt on the amp issue.

I just got done pulling the "Y" out of the Peach outputs and plugging in strictly the dbx amp. It ROCKED the entire house. Showed zero signs of strain and simply took what I threw at it.

I then pulled it (dbx) out and bridged it (since that was the mode I originally discovered this with).

Even while in bridged mode, this thing SMOKED (and I mean that in a VERY good way )

So, somehow, it's the fact of splitting the output of the Peach into the seperate amps that's giving me the headache's.

Any thoughts on why it's funky when the signal is split but the OTL's are left on verses off?

(why do I get the feeling I'm not going to like your answers exposing something dumb I did?)

[Coytee]

Mark, I don't know a thing about the OTL wiring. I DO know however, that I've had repeated fuses blowing in my left speaker. The fuse that blew was on Al's ES network and was the fuse for the woofer bin. It in fact, blew out again tonight (as I was having the cut out issues).

I cranked it with dbx only in circuit and had nothing but pure woofers woofing.

Given what's now clarifying itself, if there IS some kind of issue in one of the OTL's, I'd darn well bet it's the one associated with the left channel. I've blown probably 8 fuses on that side alone and the worst part of it... they blew during moderate listening levels.

Seems perhaps, I have an OTL that might warrant looking into huh?

I seem to recall from their website him (Bruce) saying something about because of their OTL design, dc can never get to the speakers (it might have been general comment, or might have been specific to his new amp, I don't recall)

None the less, I think we now know at least, the Peach and dbx are fine. Later on, I'll put splitter back in, leave OTL's OFF and try it again without powering them up at all.

Thanks

Richard

[Coytee]

" I'd be curious to know when you shut the OTL off, and the dBX cuts out, what happens if you wait 5 or 10 minutes with the OTL off? Does the dBX come back on? md

The dbx amp will come back on, after something like 10 seconds. It might cut right out or it might not (I now think I realize it depends on if the Peach AND dbx controls are turned down far enough)

It seems that if they ARE, then it will stay on...unless perhaps a transient comes along (speculation by me)

If it does cut back out... then I have to wait the obligatory 10 seconds or so for it to reset. I have never let it repeat this process because it annoys me that it does it. If you'd like me to try it as an experiment, I'd be happy to and report the results.

[Erik Mandaville]

Coytee:

As you know, I built one of those amps. I have built a few of them, and am fairly familiar with the design, but don't have a schematic here.

If there is a problem with one of them, I would like the opportunity to check it out for you -- certainly at no cost to you for labor. The one I made was thoroughly tested for days, and was free of any problems when shipped, but there may be a failing part or some other problem somewhere. I've got time in the next couple of weeks to do this, and would be glad to devote some time to check it out for you.

Please let me know if I can help,

Erik

[Erik Mandaville]

Mark:

This is the inside of the SE OTL -- this may even be the one I built that's now owned by Coytee. You can see the blocking capacitors on the output jacks. I wish I had a schematic here with me, but sent them all along with the amps I made to their owners (and wasn't comfortable making copies of them). Shawn may have one of the SE OTL he made.

Some of the leads seen here had been zip-tied as seen in other parts of the amp, but I found I could achieve a slightly lower level of noise with some separation, particularly in relation to the feedback leads.

Erik

edit: Nope this isn't the one, I can see the 5 watt resistors on the boards that I had to replace with slightly different (aesthetically) because they were accidentally left out of the kit. Those here are what come from Transcendent. Bruce has always been very good about that kind of detail.

[sfogg]

"I seem to recall from their website him (Bruce) saying something about

because of their OTL design, dc can never get to the speakers (it might

have been general comment, or might have been specific to his new amp,

I don't recall)"

It isn't the output of the OTL that is apparently the problem... it is

the input. On the problem amp can you power it up with the voltmeter

connected to the INPUT of the OTL with it set to read DC?

After you do that turn off the OTL and watch the meter on the amp. See if after 10 seconds or so you see a DC reading?

If so since you are 'Y'ing the cable that would be getting into the DBX and could be triggering its protection circuitry.

Shawn

[Erik Mandaville]

Those connections with the DBX sounded uncertain to me, but I've never used a DBX before. The SE OTL/Peach combination (only) was ok, then?

....actually I can read all this tomorrow.

Erik

[Coytee]

Tomorrow, I'll try to check some of the inputs as you suggest. With that said, don't lose sight of what happens. turning the OTL off was what brought this to light.

Turning it off doesn't by itself, knock the dbx amp down. If the input on the dbx is set low enough and perhaps, the Peach output is set low enough, then the two can live happy together. (albiet at modest listening levels only). If I crank (apparently) either of the gain knobs up, then the dbx will get knocked into what seems to be it's protection circuit. It will do this evidently only when the OTL is turned off. but TURNING it off, doesn't seem to be the trigger in a literal sense because the dbx WILL work with it off... just at a reduced capacity.

am i making sense? I'm off to bed & will play on it more tomorrow.

I DO appreciate everyones thoughts, as it's helped illuminate an issue that I didn't know I might have, and quelled a different issue (dbx) that I thought I DID have.