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AUDIO FORUMS >> General Discussion and Support >> My Rachel amp is pulsating when driven hard.
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Message started by bsac on 01/05/26 at 04:41:16

Title: My Rachel amp is pulsating when driven hard.
Post by bsac on 01/05/26 at 04:41:16

I just noticed some mini toggle switches near each speaker posts on my Rachel. I guessing this is an impedance switch? Possibly, a 4ohm to 8ohm switch? Hard to tell since it is not labeled. This is very frustrating part of the User Interface and User experience of Decware products because they are designed by left-brain engineers who think they know better than marketing people regarding product design. OK, I'm going to table my frustration at the moment. Anyone know which way is 4ohm and which way is 8 ohm. Once again, I would not have to ask this question if Decware just would have labeled the damn switch. NOTE: my speakers are 8 ohm. Sorry for all the bitching here but a simple label could have solved numerous customer inquiries not just mine.

Title: Re: My Rachel amp is pulsating when driven hard.
Post by busterfree on 01/05/26 at 05:40:44

I would suggest that you check the online manual. Better explanation there than a label.

Best sounding position will also depend on your speaker performance despite what the manufacturer says about their impedance rating, IMO.

I also think there is a lot of information on the UFO transformers on the forum, if that interests you. Thanks

Title: Re: My Rachel amp is pulsating when driven hard.
Post by CAJames on 01/05/26 at 12:10:08

The idea is you set the speaker impedance by ear. So listen to both and pick the one you like, you can switch them while you are playing music. For me there is very little difference between the two with my UFO25s. FWIW matching speaker impedance maximizes power transfer but no guarantee it maximizes sound quality.

Title: Re: My Rachel amp is pulsating when driven hard.
Post by Lon on 01/05/26 at 13:09:36

Listen to what Juan and James are saying. What sounds best to you is the correct setting. There are many factors that would influence preferring one setting over the other. With my Monoblocks I heard clear differences and preferred the lower setting, with my SEWE300B I hear far lesser difference but prefer the lower setting (both used with my HR-1 speakers). I suspect you will prefer one setting over the other, and there would be no harm to use that setting.

Title: Re: My Rachel amp is pulsating when driven hard.
Post by bsac on 01/05/26 at 22:09:06

thanks. The other issue I'm having is that my Rachel amp has all single-ended outputs. I'm shopping for a better DAC to put in-between my Wiim Ultra streamer and the Rachel but the DAC I'm looking at (LAIV Harmony) only offers balanced connections (no single-ended). Please advise

Title: Re: My Rachel amp is pulsating when driven hard.
Post by Lon on 01/05/26 at 22:19:51

I think you mean single-ended inputs? if so that is what the ZBIT does so admirably:

https://www.decware.com/newsite/ZBIT.html

Almost equally as good is this from Pine Tree Audio--it says it is "single-ended to balanced" but you can have it built "balanced to single-ended" and you can also have a gain control added (attenuator to adjust the gain from balanced to single-ended, very useful).

https://tinyurl.com/43r9da37

Not only is the Pine Tree Audio component nicely priced, the build wait time is only three or four weeks.

Title: Re: My Rachel amp is pulsating when driven hard.
Post by Kamran on 01/06/26 at 03:53:46

It’s in the manual.