Apt Corp. Holman Preamplifier Repair And Test

Let's track down and fix the fault in this vintage Apt Corp. Holman audio preamp that has some unusual features. Testing the preamp with an oscilloscope is shown.
#electronicsrepair #audioequipment #learnelectronics

[@joeohara2623]

I owned this same pre. Late 1970's. FYI. Thomas Holman is the THX originator; he worked for George Lucas and created the THX standards etc. I heard THX stands for Thomas Holman's eXperiment. There was a matching power amp also that was built like a tank. Thanks for the video.

[@peterlarkin762]

That's a highly regarded preamp - I always wanted one. They don't come up for sale often as owners just never want to get rid of them.

[@poormanselectronicsbench2021]

Thanks for a peek inside the Holman preamp! Years ago when I was doing my first system build, I considered one of those, but happened upon a used Threshold NS10 instead. FYI, you should consider using the "Delta" or "REL" function to zero test leads when checking for low resistance faults. It can be especially helpful if you are trying to troubleshoot a dead short without wanting to disconnect anything, as it will give you that ability to find the short by getting your test leads as close to the fault as possible with some point to point maneuvering of probes.

[@sms9106]

I have one too since the 70's and has similar issues. Have an upgrade kit to replace parts but not done anything yet. A great unit.

[@len9518]

My all time choices in a preamp, would be this one, and the Hafler DH-110. I don't think there has been anything better, before or simce.

[@user-xe9uw1of1w]

You do excellent work, very professional. The video is thorough and very easy to follow.

[@MichaelAspras-jg5gr]

Great video; thorough throughout like all the rest. Best compliment in this one is we finally got to see Erik!

[@fluxjunkie6645]

Great work .love your attention to detail.I don't work on domestic HiFi much anymore not much around worth repairing.Gone to the Pro Video and audio side.i always check frequency response with a load of at least 600 ohms or sometimes 200 ohms depending on the output impedance.Old faulty caps show up immediately wish poor low frequency response

[@martinkoskella3943]

Appreciate how thorough your repairs are. Very good pace, and you have an excellent command of language and technical explanations.

[@abeleski]

Thanks for the video. I would however prefer if you showed the unsoldering of the switch and cleaning it, removing the caps etc. Feels dry without it. Too clinical but still enjoyed it. Just my 2 cents. Thanks again for the video

[@robharley9838]

Really interesting Preamp Erik, thanks for the great run through. Never seen one of those guys, but it looks old school solid. Appreciate your process.-jrh

[@bobdoritique7347]

Thank you, how did you clean the switchs please?

[@feds27]

I had a later year Tandberg 3008a preamplifier that was serviced by Holman. I wish I had kept it.

[@linjia9539]

Finally updated, I really like watching your videos👍