KT88 ODS?

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JD0x0
Posts: 556
Joined: Tue Oct 09, 2007 2:19 am

KT88 ODS?

Post by JD0x0 »

Does anyone have a schematic to a Kt88 ODS? I think Howie (HAD) uses one of these but i cant seem to find any schematics.

I've always enjoyed the headroom and bass response of the KT88, IMO they are superior to 6L6's especially for preamp distortion amps such as the ODS
It's true i've lost my marbles and i cant remember where i put them
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David Root
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Re: KT88 ODS?

Post by David Root »

From what I've seen HAD used 6550s in his >100W amps, even the 300 watters where the KT88 higher plate voltage capability could be useful. He used SVT iron in those I believe, so the OT would be set for 6550s. No reason you couldn't use KT88s though, but you might need a different OT primary impedance as I believe the 6550 is less fussy about that.
ampdork
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Joined: Sat Oct 21, 2006 4:53 am

Re: KT88 ODS?

Post by ampdork »

I've done a MM high plate voltage amp with kt88's.
It's very nice in my opinion.
Have tried them with the standard bassman and twin iron and I think they like the higher plate voltages a lot more. The high plate voltages bring the kt88's to life. Without the high voltages I kinda though...meh....with it.... :O)
Of course I do not think Howard ever used kt-88's as pointed out so what I did is off the path....but I'd say if your going to use kt88's look to changing the iron to something that can take advantage of the tubes ability to handle voltages....my opinion anyway.
Bias circuit is the only place I have found that needs tweaking to run kt88's.
6550's are reported to be a pain in the datasheets but lots of designs have gotten away without.
JD0x0
Posts: 556
Joined: Tue Oct 09, 2007 2:19 am

Re: KT88 ODS?

Post by JD0x0 »

ampdork wrote:I've done a MM high plate voltage amp with kt88's.
It's very nice in my opinion.
Have tried them with the standard bassman and twin iron and I think they like the higher plate voltages a lot more. The high plate voltages bring the kt88's to life. Without the high voltages I kinda though...meh....with it.... :O)
Of course I do not think Howard ever used kt-88's as pointed out so what I did is off the path....but I'd say if your going to use kt88's look to changing the iron to something that can take advantage of the tubes ability to handle voltages....my opinion anyway.
Bias circuit is the only place I have found that needs tweaking to run kt88's.
6550's are reported to be a pain in the datasheets but lots of designs have gotten away without.
Thanks, maybe you havent heard of HAD using KT-88's because (from what i heard) they were used for his "personal amp"

i'll be using a Weber-Marshall 100 watt power tranny because of the larger heater amperage (1.6A vs .9) and they can run KT88's im still not 100% on the OT though
It's true i've lost my marbles and i cant remember where i put them
dr. who
Posts: 481
Joined: Fri Feb 16, 2007 8:36 am

Re: KT88 ODS?

Post by dr. who »

150W Overdrive Special-
"In 1987, Dumble made two otherwise unique amplifiers for Todd Sharp at 150W utilizing signature components from several of his other famous models. The power supply is similar to that of the 150W Dumbleland amplifier, but using 7025 tubes as in the Steel String singer. It is switchable from 150W to 75W. Preamp tubes are: a)6 x 7025, b)1 x 7247, c)1 x 5751 while the poweramp uses 4 x 6550A tubes."
JD0x0
Posts: 556
Joined: Tue Oct 09, 2007 2:19 am

Re: KT88 ODS?

Post by JD0x0 »

I think i found it. Dumble #121
ODS
http://personalpages.manchester.ac.uk/s ... 20%230121/

Apparently it has reverb and tremolo too
It's true i've lost my marbles and i cant remember where i put them
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