Problems with Dual Mono amp and 1000VA A-L AI-1

drumminman

I’m stumped and I need some ideas. I sent my Odyssey Stratos stereo amp in to be converted to Dual Mono last summer. When I received it I connected it to my HT for 16 hour per day burn in, and then back into the big rig. After the conversion it ran warm to hot in the HT which has no SDA speakers.

When I put it back into the main system I connected both SDA cables to the AI-1, which was brand new and just assembled from the group buy conducted by fjross. Everything sounded really good, though there was a little more SDA effect on the right side than the left. I attributed this to the room layout.

From July to January everything worked as it should, and then around mid-January I was playing music one Saturday am and I heard a pop. The left channel stopped working, and when I touched the amp it was hot! So hot I couldn’t leave my hand on it. Popped the top and saw two blown fuses, which I replaced. Powered up the amp and the left channel played at about ½ the volume of the right.

Called Klaus at Odyssey and he said send it back and we’ll get it fixed. Also decided to do some more upgrades while he had it: had him swap out the standard power supply caps to the reference grade (a review coming).

Received the amp back Monday, connected it in the usual way using the AI-1 transformer, and things were great – for about 45 minutes. I kept checking the amp temp and it was fine at first. Then it slowly began to get warmer. It then became very hot as above, and all of a sudden a loud hum developed from both speakers. Called Klaus and described the situation to him and he was dumbfounded as he had run it for 4-5 days straight to be sure it was working properly. For him the heat sinks/outer case temp never rose above warm.

I checked all my cables (speaker, IC’s from linestage to amp, SDA cable) to be sure that there were no shorts and found nothing out of the ordinary. So at Klaus’ suggestion I powered up only the left channel (right channel off) and played music for 45 minutes: no hum, the music sounded good and the amp stayed cool to the touch. But . . . I thought it odd that I could hear the SDA signal coming out of the non-powered up right channel (is this a key piece of information?). Though the SDA signal is passed by the AI-1 wouldn’t the right channel need to be powered up for the SDA mw’s to make sound?

Repeated above with only the right channel powered up with the same result. Now I’m really scratching my head.

On a hunch I removed the AI-1 and left the SDA cable disconnected. Voila! Perfect sound except no SDA effect. Fantastic stereo image, amp ran flawlessly for over two hours at “wife driven from room” volume. Temp barely warm.

I double checked the connection of the wiring of the AI-1to the BP’s and it’s correct.

I don’t want to get rid of the amp and I’d like to get the SDA effect back., but I don’t know what else to look for, trouble shoot, etc. Any suggestions on how I can proceed, what to check, measure, etc.?

BTW, kudos to Klaus – he has been a total gentlemen through all this. I really appreciate good customer service. He was in the process of building a new chassis for me so that when I returned the amp he could convert to mono blocks at no additional cost to me. That is until I discovered that the amp seems fine.

zingo

Eeww, that's disappointing and no fun to trouble shoot.

Have you tried the speakers with a different non-common ground amp and the AI-1? I see if you can borrow one, and if you still have the same problem, than the issue it your AI-1. If you do not have the issue, than the problem would point to the amp; but you could also try the same test borrowing a different AI-1.

With a weird and frustrating issue like this, I just try to eliminate/swap components one by one until I can find and identify the problem.

Good luck!

F1nut

I thought it odd that I could hear the SDA signal coming out of the non-powered up right channel (is this a key piece of information?).

That's working exactly as it should.

I double checked the connection of the wiring of the AI-1to the BP’s and it’s correct.

I've got to think something is amiss there. Can you describe exactly how you have what connected to what, maybe take some pics?

drumminman

F1nut wrote: »

That's working exactly as it should.



I've got to think something is amiss there. Can you describe exactly how you have what connected to what, maybe take some pics?

Will do when I get home tonight.

It's hard to believe something is wrong with the transformer, and the amp works flawlessly without it or the SDA cable attached. Must be something I've done, though I can't work it out.

VR3

Glad to hear this is worked out! :]

FTGV

I would be double checking the wiring of the trans ,it appears that the amp is seeing some sort of nasty load.

drumminman

Ok, took pics but I can't get them to load cause the files are too big, both the camera phone and dslr.

Wiring is as follows:

Left channel + : grey/brown
Left channel - : blue/violet

Right channel + : red/yellow
Right channel - : black/orange

The soldering to all the BP's appears to be solid and connected.

drumminman

Ok, finally got some low res pics to upload. This pic is the left channel, the ones below start with the right channel.

For each connection one of the wires is inserted into the hole in the BP with the other in the pair twisted to it and both soldered together and to the BP.

drumminman

VR3 wrote: »

Glad to hear this is worked out! :]

The problem is still there, only it's not the amp. Or at least the amp is working great as long as the AI-1 is out of the system, which means I have no SDA effect. So it's either something in the amp design, or the AI-1 transformer.

VR3

Man I wish I could be of help on the Ai1 - that is outside my territory, never even seen one in person but I understand the idea behind it - seems like there is not much that can go wrong...

Best of luck!

F1nut

Ok, that wiring looks correct. What about at the speaker end, how do you have that hooked up?

Left channel + : grey/brown
Left channel - : blue/violet

Right channel + : red/yellow
Right channel - : black/orange

The + should be connected to the pin blue wire and the - should be connected to the blade white wire.

drumminman

I'll have to pull the PR and have a look- this pm or tomorrow.

drumminman

Tonight I checked the Xover wiring: on both speakers the wire from the IC binding post to the Xover board connects at the IC position in the P1 input molex connector. As far as the speaker connections the IC BP is connected to pos on the AI-1 and the IC neg to the negative on the lower set of BP's on the speaker and the neg BP on the AI-1. The same for both channels


I sent Klaus at Odyssey the schematic and he's going to have his technical guy look at it. His first thought is that the AI-1 is showing the amp something in the way of a dead short.

Anyone think that somehow the 1000 VA tranny in the AI-1 could have somehow become damaged? This seems like a long shot as it doesn't see much current.

FTGV

If all other wiring seems correct maybe the colour coding of the windings of the tranny were inadvertantly misapplied?Is there a drawing of the tranformer showing the winding labeling?

SCompRacer

FTGV wrote: »

If all other wiring seems correct maybe the colour coding of the windings of the tranny were inadvertantly misapplied?Is there a drawing of the tranformer showing the winding labeling?

I'm thinkin' he can use a DMM (Digital Multimeter) and Ohm it out to make sure?

FTGV

Yes you could use the meter to identify what two colours are on each winding.

headrott

Fred, could your replacement Solen inductors (the ones the crossovers are normally connected to) that have a lower DCR cause this/these problem(s) with your amp? That was my first thought. Or, did this problem start only after you installed the AI-1? I don't remember if you installed the AI-1 or had your amp converted to a dual mono first?

headrott

Ammendment to my above post: That is, I know you said it's when the AI-1 is hooked up, but could the Solen inductors (with low DCR) and the AI-1 have some kind of interaction with the new dual mono to cause this overheating and eventual failure in the amp?

Although, a miswiring in the transformer coule be possible as suggested (although, not likely).

headrott

FTGV wrote: »

If all other wiring seems correct maybe the colour coding of the windings of the tranny were inadvertantly misapplied?Is there a drawing of the tranformer showing the winding labeling?

I believe it's the same as the AL Y236906 transformer.

drumminman

SCompRacer wrote: »

I'm thinkin' he can use a DMM (Digital Multimeter) and Ohm it out to make sure?

I'd like to rule out problems with the AI-1. What setting would I use on the DMM and what would the procedure be?

headrott wrote: »

Fred, could your replacement Solen inductors (the ones the crossovers are normally connected to) that have a lower DCR cause this/these problem(s) with your amp? That was my first thought. Or, did this problem start only after you installed the AI-1? I don't remember if you installed the AI-1 or had your amp converted to a dual mono first?

It could be some interaction like this, but I used this AI-1 without incident for 6 months with the Solen inductors in place. Before that I used an AI-1 with the 800 VA A-L tranny (again with Solen inductors in place) without incident for a year. The latter was with a stereo Stratos though.

I don't get why I get a loud hum that's independent of the volume. IOW it doesn't go up or down when increasing or decreasing the volume through the linestage.

SCompRacer

drumminman wrote: »

I'd like to rule out problems with the AI-1. What setting would I use on the DMM and what would the procedure be?

The transformer is to keep the speakers connected via induction inside the transformer windings. That is no physical or hard wired complete circuit between speakers. Testing with Ohm meter will show a short, or physical connection, between speakers.

With your AI-1 disconnected from speakers, set DMM to Ohms and measure resistance between left channel pos and neg and right channel pos and neg. I'm thinking you will get some resistance going through windings of transformer for each channel. Both channels should measure close to same.

Still on Ohms, check for reading between right channel and left channel pos, R and L channel neg, R and L neg to pos. Meter should read OL or 'out limits' or no reading, or you would have a short between R and L channel windings. The Ohm meter does not pass enough current to make that induction connection happen between speakers.

drumminman

SCompRacer wrote: »

The transformer is to keep the speakers connected via induction inside the transformer windings. That is no physical or hard wired complete circuit between speakers. Testing with Ohm meter will show a short, or physical connection, between speakers.

With your AI-1 disconnected from speakers, set DMM to Ohms and measure resistance between left channel pos and neg and right channel pos and neg. I'm thinking you will get some resistance going through windings of transformer for each channel. Both channels should measure close to same.

Still on Ohms, check for reading between right channel and left channel pos, R and L channel neg, R and L neg to pos. Meter should read OL or 'out limits' or no reading, or you would have a short between R and L channel windings. The Ohm meter does not pass enough current to make that induction connection happen between speakers.

Thanks! Will try that and report back.

SCompRacer

Technician A says that a transformer problem is highly unlikely; don’t bother checking….Technician B says though unlikely it is possible so I will test the toroidal and hope to eliminate it as a possible cause.

The only other thing I can think of is somehow the AI-1 is causing or amplifying oscillations the amp picks up on? Would it create a capacitive load the amps don't like? Once upon a time a fellow with system like mine (same ESL speakers and amps) could send his amps into oscillation where they would get hot playing specific SACD's through a tubed CD player. It required a high frequency filter installed in the output of the modded player. Just reaching here...no other ideas as to cause.

FTGV

headrott wrote: »

Ammendment to my above post: That is, I know you said it's when the AI-1 is hooked up, but could the Solen inductors (with low DCR) and the AI-1 have some kind of interaction with the new dual mono to cause this overheating and eventual failure in the amp?

While the reduced DCR will make for a more difficult load he is only having the issue on one ch.

Although, a miswiring in the transformer coule be possible as suggested (although, not likely).

It's a long shot but if he has ruled out everything else he might want to look a little closer at the transformer and how it's wired.

drumminman wrote: »

I'd like to rule out problems with the AI-1. What setting would I use on the DMM and what would the procedure be?

Diode check/continuity would be fine.You need to find the drawing of the transformer and determine which colours are associated with each of the two windings on the ch your having the issue with.Then with the meter test for continuity from one lead out wire to the other.If the proper coloured lead out wires have continuity between them then the tranny is fine.If the wrong colored lead out wires have continuity between them that would be an issue.

headrott

drumminman wrote: »

I'd like to rule out problems with the AI-1. What setting would I use on the DMM and what would the procedure be?



It could be some interaction like this, but I used this AI-1 without incident for 6 months with the Solen inductors in place. Before that I used an AI-1 with the 800 VA A-L tranny (again with Solen inductors in place) without incident for a year. The latter was with a stereo Stratos though.

I don't get why I get a loud hum that's independent of the volume. IOW it doesn't go up or down when increasing or decreasing the volume through the linestage.

To me, it seems the loud hum you get independent of volume would be due to something grounding somewhere that should not be. What that is however, I couldn't guess. You would have to check with a DMM (as suggested). It could be in the transformer (AI-1) it could be in the speaker crossover (maybe) or it could be in the amp.

I just thought, are there any holes in the wrap of the AI-1 tranformer causing exposed winding(s) to touch the chassis? I'm reaching now, but just a thought.

drumminman

A little bit of miscommunication here- the problem is in both channels when both are powered up and the IC is connected to the AI-1. But when either channel is powered with the other being off there's no home and no issue. You can hear the channel powered and the SDA mw's in the other channel, just as clean as it should be. It's only when both are powered on at the same time.

Per SComp's suggestion I got out my DMM, set it to 200 ohms and got the following readings taken at the binding posts:

Left channel: pos to neg - 0.03 Right channel: pos to neg - 0.03

Left pos to Right neg - 1.00
Left neg to Right pos - 1.00
Left pos to Right pos - 1.00
Left neg to Right neg - 1.00

Not sure what this means - anyone?

drumminman

A little bit of miscommunication here- the problem is in both channels when both are powered up and the IC is connected to the AI-1. But when either channel is powered with the other being off there's no home and no issue. You can hear the channel powered and the SDA mw's in the other channel, just as clean as it should be. It's only when both are powered on at the same time.

Per SComp's suggestion I got out my DMM, set it to 200 ohms and got the following readings taken at the binding posts:

Left channel: pos to neg - 0.03 Right channel: pos to neg - 0.03

Left pos to Right neg - 1.00
Left neg to Right pos - 1.00
Left pos to Right pos - 1.00
Left neg to Right neg - 1.00

Not sure what this means - anyone?

Re: the hum, it does sound like a grounding problem, only it disappears when only one channel is powered per above. I suppose I should have a look at the transformer and see if there's any physical damage.

SCompRacer

drumminman wrote: »

Left channel: pos to neg - 0.03 Right channel: pos to neg - 0.03

Left pos to Right neg - 1.00
Left neg to Right pos - 1.00
Left pos to Right pos - 1.00
Left neg to Right neg - 1.00

Not sure what this means - anyone?

I'm thinkin' there should be no reading between R and L channel at all. The whole idea of the 1:1 transformer is to prevent a physical or hard wired complete circuit between the speakers. Years ago I had a Polk AI-1. I recall getting a reading between blade and pin of each respective channel or connector side of transformer; but zero, zip nada between R and L channel pin/pin, pin/blade etc. If someone here that has the uber AI-1 like yours perhaps they could measure theirs so we would have something to compare to.

FTGV

SCompRacer wrote: »

I'm thinkin' there should be no reading between R and L channel at all. The whole idea of the 1:1 transformer is to prevent a physical or hard wired complete circuit between the speakers.

Exactly.If wired correctly there should be complete isolation between primary and secondary windings.

F1nut

I'm thinkin' there should be no reading between R and L channel at all.

I concur.

drumminman, do you still have the 800V transformer?

headrott

Confirmed. I get a 0 ohm reading between the left and right binding posts on my AI-1 Dreadnought (both positive and negative). You don't have a cold solder joint on one of the binding posts (or both) do you Fred? If you do not, it it is most likely a miswiring of the transformer primaries and secondaries. Very very low chance of occurance but not impossible of course. I would check you solder joints first though; especially since you said everything was working correctly when you first started using the AI-1.