hi there, just wanted to know if anyone here has, or has had, a gibson eh-150 amplifier? i've found a beat-up one in need of restoring, and thought i might do some minor modifications as i will never sell this (been looking for years!)and i want it to be a player!
has anyone used the "echo speaker" output on this amp? i'm wondering if i'd be able to convert this to an external speaker output , so i could run this beautiful beast through a bigger cabinet. any thoughts?
can i also just confirm if it's 15 watt or 25 watt? (i don't have it yet obviously)
thanks for looking
chris
gibson eh-150 eh150 amplifier question
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Christiaan van der Vyver
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Eric Philippsen
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I've had an EH-150. There are actually several variations on the model and you can date it down to the year based on its cabinet and control panel features. A google of the internet will reveal several sources of info relating to the amp.
The "Echo speaker" output you refer to is actually an auxiliary speaker jack! That relates to one of the unusual features of the amp in that that its output transformer adjusts to the added load when another speaker is plugged in.
Almost every EH-150 requires an overhaul and tune-up due to their age. Some of the tubes are hard to find.
The output of the amp is not a lot.
If I might, please think seriously about your plans to modify an EH-150. Any drilling of the chassis, changing the speaker or cabinet, or drastically altering the circuitry essentially ruins what is now a historical vintage piece. Doing a simple, reversible mod to the circuitry can be done so long as the old parts are saved. Thanks for allowing me to say that.
The "Echo speaker" output you refer to is actually an auxiliary speaker jack! That relates to one of the unusual features of the amp in that that its output transformer adjusts to the added load when another speaker is plugged in.
Almost every EH-150 requires an overhaul and tune-up due to their age. Some of the tubes are hard to find.
The output of the amp is not a lot.
If I might, please think seriously about your plans to modify an EH-150. Any drilling of the chassis, changing the speaker or cabinet, or drastically altering the circuitry essentially ruins what is now a historical vintage piece. Doing a simple, reversible mod to the circuitry can be done so long as the old parts are saved. Thanks for allowing me to say that.
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Christiaan van der Vyver
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eh 150 amp
hi there, thanks eric for your reply! it probably sounds like i'm going to hack the amp apart but have no fear!....
looks like i won't need to modify it for external speaker out after all this is great news!
so what ohms would the external speaker need to be is there any way of finding that out?
thanks
chris
looks like i won't need to modify it for external speaker out after all this is great news!
so what ohms would the external speaker need to be is there any way of finding that out?
thanks
chris
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Eric Philippsen
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Kevin Mincke
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Murray Leshner
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Re: gibson eh-150 eh150 amplifier question
Old post, but for anyone in the future...
The EH-150 schematics I've seen with the Echo Speaker jack had a switching jack. The internal field coil speaker voice coil went to the 8-ohm tap on the output transformer secondary, through the normally-closed switching jack. When the echo speaker was plugged in, it was in parallel with the field coil speaker and the echo speaker jack switch selects the 4 ohm tap on the output transformer secondary, so both had 8 ohm voice coils.
I finally met someone who had seen an Echo Speaker in person. It was a permanent magnet speaker, with a 35' cord. Permanent magnets from that era were not very impressive...a mid-30's Jensen patent for a electrodynamic (field coil) speaker claimed the electromagnet was an improvement over the PM speakers of the era.
I had tried to convince myself that no one would do something as weird as running field coil B+ to a remove field-coil speaker. That was true that Gibson EH-150 did not, but I found a scanned mid-1930's catalog that showed Jensen offering PA systems with remote field coil speakers using 25' cables carrying both field coil B+ & and voice coil signal (power from output transformer secondary).
The EH-150 schematics I've seen with the Echo Speaker jack had a switching jack. The internal field coil speaker voice coil went to the 8-ohm tap on the output transformer secondary, through the normally-closed switching jack. When the echo speaker was plugged in, it was in parallel with the field coil speaker and the echo speaker jack switch selects the 4 ohm tap on the output transformer secondary, so both had 8 ohm voice coils.
I finally met someone who had seen an Echo Speaker in person. It was a permanent magnet speaker, with a 35' cord. Permanent magnets from that era were not very impressive...a mid-30's Jensen patent for a electrodynamic (field coil) speaker claimed the electromagnet was an improvement over the PM speakers of the era.
I had tried to convince myself that no one would do something as weird as running field coil B+ to a remove field-coil speaker. That was true that Gibson EH-150 did not, but I found a scanned mid-1930's catalog that showed Jensen offering PA systems with remote field coil speakers using 25' cables carrying both field coil B+ & and voice coil signal (power from output transformer secondary).
Murray
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Kevin Mincke
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Re: gibson eh-150 eh150 amplifier question
Great info as I have an EH-185.