6C45P availability question

Loquah · 10255

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Offline Paul Birkeland

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Reply #15 on: April 14, 2014, 01:03:27 PM
Yes and no.

If you go through biasing the amplifier to dial in the plate voltage, you will receive the maximum possible output power from the Mainline.

If you don't, you may not receive all the power that the amplifier has to offer.

Whether or not this matters depends upon many conditions, including the headphones being driven, how loudly you want to listen, etc. 


Paul "PB" Birkeland

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Offline Loquah

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Reply #16 on: April 14, 2014, 03:51:54 PM
Yes and no.

If you go through biasing the amplifier to dial in the plate voltage, you will receive the maximum possible output power from the Mainline.

If you don't, you may not receive all the power that the amplifier has to offer.

Whether or not this matters depends upon many conditions, including the headphones being driven, how loudly you want to listen, etc.

In theory then could failing to bias for new tubes result in a tiny channel imbalance?

Check out my reviews on YouTube - https://youtube.com/c/passionforsound


Offline Paul Birkeland

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Reply #17 on: April 14, 2014, 05:14:30 PM
No, more that if you had one channel perfectly biased, you'd see maximum output power.  If the other channel wasn't properly biased, you'd see something less than that.

This would equate to different THD between channels at maximum power, with the asymmetrical clipping potentially reducing the gain a little bit in that channel.  Again, this is only at maximum power.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Loquah

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Reply #18 on: April 14, 2014, 05:37:30 PM
I understand. Thanks for the great explanation!

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Offline dubiousmike

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Reply #19 on: April 25, 2014, 07:40:11 AM
In the event anyone is looking to pick up a couple spare pairs of 6c45pi tubes, this NIB 4 pack is the lowest price I've seen on ebay in a while ($15 per tube, including shipping).  Several months ago, I managed to snag a couple of pairs from a US seller for only $10 per tube, but haven't seen anything this low since.  Nixiestore also seems to be a pretty legit seller so I pulled the trigger on four more last night.  Figured I'd share the link while a few lots are still available: http://www.ebay.com/itm/4-x-6S45P-E-6C45P-WE437-EC8020-NEW-TUBES-NIB-OTK-/390820796896?pt=Vintage_Electronics_R2&hash=item5afebc19e0   

I've spent more hours than I'd care to admit hunting for a reasonable price on the electro-harmonix version.  $100 through woo still feels excessive, although I gather that supply and demand suggest my feelings are in error heh.

Mike M.


Offline rlyach

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Reply #20 on: April 25, 2014, 08:26:17 AM
Thanks for the heads up Mike. I snagged a set for myself. Apparently they are Gold Grid wires. Paul indicated they needed to be platinum to be true 6C45pi tubes. I wonder what gold grids will sound like?

Randy Yach


Offline Paul Birkeland

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Reply #21 on: April 25, 2014, 08:37:35 AM
Thanks for the heads up Mike. I snagged a set for myself. Apparently they are Gold Grid wires. Paul indicated they needed to be platinum to be true 6C45pi tubes. I wonder what gold grids will sound like?

Hmm, I wonder if they switched at some point.  I wouldn't be concerned with any old production 6C45's.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline NightFlight

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Reply #22 on: April 22, 2015, 10:13:50 AM
Hmm, they are starting to get more rare. I hope you guys have enough stock for your kits.

http://www.ehx.com/products/6c45pi-gold

My local retailer went to EHX to get a quote, but EHX would not sell them unless they are were part a bulk purchase of 50+ at $35-40ea Canadian after markup to retail, exchange and lets not forget tax.  Apparently they buy that much about once every 6 months or so and would be willing to put my order in that way.



Offline Grainger49

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Reply #23 on: April 22, 2015, 11:43:54 AM
Lots of them are $10-$12 (US) on ebay.