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previous: MitchK Hey I just have some questions if a... -- 10/8/2004 5:28 AM

Re: KT88 vs. 6550 high current

10/8/2004 2:59 PM
Brutus	Re: KT88 vs. 6550 high current KT-88's clearly have a higher plate disipation of several watts. If you need the exact number I'll dig it out for you. Also, a 6550 is rated at a max plate voltage of 600v while a KT-88 is rated at a max B+ of 800v. These stats are for the Original KT-88 made by MO Valve Company of England. I have no idea what passes for a KT-88 these days from the clone manufacturers. In general, you can use a KT-88 in place of a 6550 but you cannot always use a 6550 in place of a KT-88 because of the voltage handling difference. Under 600v they bias slightly differently but still can often be plug compatable. I use KT-88's in my McIntosh MC-60 hifi amp even though it was designed for 6550's, for example. Also, there is a difference in sound between the two tubes but not greatly. For example, I've repeatedly substituted the KT-88 for the 6550 in my Mac Amps and vice-versa and can only hear the difference on a good day. I think part of this can be explained by the heavy use of negative feedback within the Mac which would eliminate some of the perceived difference. I suspect that in a guitar amp the differences may be more pronounced. Brutus

10/8/2004 2:59 PM

Brutus

Re: KT88 vs. 6550 high current

KT-88's clearly have a higher plate disipation of several watts. If you need the exact number I'll dig it out for you. Also, a 6550 is rated at a max plate voltage of 600v while a KT-88 is rated at a max B+ of 800v. These stats are for the Original KT-88 made by MO Valve Company of England. I have no idea what passes for a KT-88 these days from the clone manufacturers.

In general, you can use a KT-88 in place of a 6550 but you cannot always use a 6550 in place of a KT-88 because of the voltage handling difference. Under 600v they bias slightly differently but still can often be plug compatable. I use KT-88's in my McIntosh MC-60 hifi amp even though it was designed for 6550's, for example.

Also, there is a difference in sound between the two tubes but not greatly. For example, I've repeatedly substituted the KT-88 for the 6550 in my Mac Amps and vice-versa and can only hear the difference on a good day. I think part of this can be explained by the heavy use of negative feedback within the Mac which would eliminate some of the perceived difference. I suspect that in a guitar amp the differences may be more pronounced.

Brutus