Radiohead Posted January 16, 2003 Share Posted January 16, 2003 Sorry for such a newb question but what do you'll have your speakers hooked up to on the HF-81? 4 ohms or 8 ohms? When I first received the unit about a year ago I was always using the 8 ohm tap because the Klipschorn's nominal impedence is 8 ohms. Last night I reconnected it for the first time in about two months to the 4 ohm output. Seems to me like the sound may be a bit cleaner and the transformers don't run as hot which I thought was strange because I expected they would run hotter. Anyone have any negative experiences connecting at 4 ohms that they would like to share? Am I running any risk to the amp or speakers by doing this? rcr Quote Link to comment Share on other sites More sharing options...
Radiohead Posted January 17, 2003 Author Share Posted January 17, 2003 Anyone? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 17, 2003 Share Posted January 17, 2003 If the amp runs cooler and you like the sound, I don't think I would worry about it. But that's me. Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 17, 2003 Share Posted January 17, 2003 That's a good question. From what I've read... You effectively get a doubled output transformer primary impedance when you do this. That translates to lower distortion, slightly lower output power and better damping factor. I don't know if that will hurt anything or not. I have some Kg4 which are 6 ohm, and I've always run it using the Eicos 8 ohm tap. I have not tried the 4 ohm, but I'll give it a try this weekend and let you know my thoughts. - tb Quote Link to comment Share on other sites More sharing options...
Radiohead Posted January 17, 2003 Author Share Posted January 17, 2003 mike and tb, Thanks for the response. I think I will leave them this way for a little while and see how everything turns out. I look forward to hearing your input on the matter when you have the chance tb. Ryan Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 17, 2003 Share Posted January 17, 2003 Using the 4ohm taps will not hurt the amplifier. In fact, I recommend just trying the 4ohm tap for anyone to see if it make an improvement. OBviously, you would first look to match the speaker impedance with the proper tap..ie if your speakers are rated ata nominal 8ohms, then most use the 8 ohm tap. Ditto if speakers have a 4 ohm rating. Move to the 4ohm. On the other hand, I have found that speaker measurements are tricky at best. Some dip down in all the wrong places and you can have amp interaction that is more problematic. That is why I tell people to just TRY IT OUT AND LET YOUR EARS decide. Some amps do better on the 4 ohm taps...sometimes, the 4 ohm tap will make a good pairing, even with a higher rated speaker. I personally use the 8ohm taps on my EICO for most of my application but have run it on 4 ohm for some speakers at a family member's house. So...if you like the sound better, go with it. As for the trans temp, the power trans on these EICOS ALL run very hot. If you are pushing the amp, it will even get almost too hot to leave your fingers on the trans for more than a few seconds. While this may be shocking to some, it it really normal for the EICOS. I have been around a number of the units and they ALL are like this. It is rated to run at 195F all day but is designed to stand 221F without stress. kh Quote Link to comment Share on other sites More sharing options...
@silverfox@ Posted January 17, 2003 Share Posted January 17, 2003 tb,kh,craig! could the use of the 4ohm tap be use for any tube amp? or does the circuitry of the eico lends itself to be configured in this way. my familliarity with any form of electronics is limited so my reasoning might be impaired.from other posts reguarding low wattage amps,would this type of application bring the amp towards the lower wattage principle.the first clean watt brings the best sound. with all the resistance beign fixed does this then make the amp,produce a higher current or lower current to the speakers. thanks for any imput. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 17, 2003 Share Posted January 17, 2003 Sure you can play with either 4 ohm or 16 ohms. We could start a new trend ! Sure would be cheaper than tube rolling or wire changing Quote Link to comment Share on other sites More sharing options...
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