OTS HRM preamp tubes

mr fabulous
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OTS HRM preamp tubes

« on: May 06, 2010, 05:29:48 PM »

i recently swapped the original JJ preamp tubes in OTS for Electro Harmonix 12ax7's.... i must say the difference is remarkable!!!!!, my strat is more musical, in both the clean and dirty channels. but the dirty channel now chimes more and nails the mayer/SRV tones very well. my 335 now gets a tone close to greg allman/dicky betts.

i have ordered some reissue mullards now to see if there is any further improvement. in comparison, the jj's sounded a little dark, but did have more gain.

i wonder is anyone else has experimented with different preamp tube brands? i'd love to hear some opinions


« Last Edit: May 06, 2010, 05:35:04 PM by mr fabulous »	Logged

mr fabulous
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Re: OTS HRM preamp tubes

« Reply #1 on: May 06, 2010, 06:35:26 PM »

Quote from: ToneQuest on May 06, 2010, 06:30:16 PM

I like Tung-Sol 12AX7.

thanks... i hear the tung sols are toppy


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rane008
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Re: OTS HRM preamp tubes

« Reply #2 on: May 06, 2010, 08:00:02 PM »

Doesn't the OTS have a cathode follower on the V2? If it does, I have heard that the TS-RIs will not be able to handle the current. That comes from one of the guys at tubedepot.com, but I could be wrong about that.


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rane008
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Re: OTS HRM preamp tubes

« Reply #3 on: May 06, 2010, 09:08:13 PM »

Thanks, Tonequest. Good info.

Any use any of the TAD "telefunken" 12ax7 clones?


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erwin_ve
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Re: OTS HRM preamp tubes

« Reply #4 on: May 07, 2010, 08:52:19 AM »

Quote from: rane008 on May 06, 2010, 09:08:13 PM

Thanks, Tonequest. Good info.

Any use any of the TAD "telefunken" 12ax7 clones?

Yes I do; 7025 high grade selected, one of the best new production tubes around!


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erwin_ve
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Re: OTS HRM preamp tubes

« Reply #5 on: May 08, 2010, 01:04:46 PM »

Hi ToneQuest:

I think I use these: http://www.tubeampdoctor.com/product_info.php?cPath=21_60_63&products_id=390

I don't care what the recomendations are; they are v1 and PI in my OTS and fender amps.

The OTS doesn't have a cathode follower at v2. For other amps; I never tried them in a cathode follower/recovery triode setup.

Don't mind the sales pitches on the TAD website.
Only thing I noticed they don't draw much current so the plate voltage is higher in comparison to a JJ ECC83.


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mr fabulous
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Re: OTS HRM preamp tubes

« Reply #6 on: May 11, 2010, 02:31:12 AM »

after some more experimentation i have found the following:

clarity in the amp is dependent in V1 and v3
overdrive tone is dependent on V2 (of course)

jj's in V1 and V3 (one or both) sound dark and you lose a lot of top end, however the gain is higher

so far i have found EH's sound better in V1 and V3 with jj for V2

this gives enough gain and beef whilst the other 2 take care of passing the signal transparently

i'll provide an update when i get my mullards


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JD0x0
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Re: OTS HRM preamp tubes

« Reply #7 on: May 11, 2010, 02:46:55 AM »

i like tungsols in all positions, but i like the overdrive even more with the old RCA i have in there, much fatter. IMO the JJ's in V3 kill the harmonics and bloom and in V1 it makes the clean channel lifeless.

JJ's are now only used as test tubes by me due to their ruggedness


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Steven_nl
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Re: OTS HRM preamp tubes

« Reply #8 on: May 11, 2010, 07:47:08 AM »

Don't underestimate the importance of Power Tubes either. I'm using Tung Sol 5881's now. They sound nice but I'm not sure sure they can handle the 450V for a long period of time.

I have JJ's in V1 and V2 and a Sovtek LPS in V3


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mr fabulous
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Re: OTS HRM preamp tubes

« Reply #9 on: May 11, 2010, 08:45:38 AM »

great to hear... i'll have to try tung sols....

anyway, Today I received the mullard 12ax7's

They are broad spectrum and aggressive.

After swapping all combinations of valves i found the following:

Mullard for V1: just drives the preamp harder. Drives the clean channel to break up. Its aggressive sound is perfect to drive V2 stage.
JJ for V2: it’s the best for V2 as its warmth and midrange is better for the OD
Mullard or EH for V3: mullard better for rock or more edgy blues, its got more output and drives the output tubes harder the overall tone is more agressive. EH gives a sweeter tone in general, and is probably better for blues or jazz (a little tamer)

Mullard definitely has a much higher gain (gm) as they run hotter than the EH and the JJ.

I'll provide an update once I have run these in for a while in this config.

i wonder if anyone else has used these new reissue mullards.... Huh?


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mr fabulous
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Re: OTS HRM preamp tubes

« Reply #10 on: May 12, 2010, 05:33:41 AM »

Quote from: rane008 on May 06, 2010, 08:00:02 PM

i have the schematic of the HRM and the V2 section is definitely not cathode follower. so there would be no problem using whetever tuve suits your ears in that position

i am curently writing a manual for the HRM. i offered this to nik so that he can focus on doing what he does best, building great amps for all of us. the first draft has already been commented on by nik and after a few more revisions, i will post it for all and sundry. i will include a technical section with,schematics, tables of correct voltages and biasing instructions as well.

i also plan to include some settings as well as the basis for getting certain tones etc.


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rane008
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Re: OTS HRM preamp tubes

« Reply #11 on: May 12, 2010, 04:37:17 PM »

Hey Mr. Fabulous,

A manual would be great! So many questions out there. Could you link it up here when you're done (or before

, hehe).

Looking forward to it!

Stephen


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mr fabulous
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Re: OTS HRM preamp tubes

« Reply #12 on: May 13, 2010, 02:22:40 AM »

yes of course i will link it up here too (with nik's permission of course)

fab


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fumblefingers
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Re: OTS HRM preamp tubes

« Reply #13 on: May 23, 2010, 06:00:27 PM »

Thanks for taking the time to write the manual.....I have a 100wHRM on order, and I have gathered from the forum that there are specific control settings that allow the player to get the most from this amazing sounding amp. Will you announce when the manual will be available?


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mr fabulous
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Re: OTS HRM preamp tubes

« Reply #14 on: May 23, 2010, 11:18:17 PM »

yes of course
i did some more work on it last night, adding stuff Nik suggested
it will still be a week or so.....and i want to get Nik's ok on it too.

bear in mind... the settings will vary as well depending on the guitar you use with it...the amp reacts vastly different to different types of pickups.

the Kleinulator also affects the tone as well; even without effects units plugged into it


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