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Alan Kimmel OTL

61.18.170.144
Posted on December 18, 2011 at 21:23:48
Tube747
Audiophile

Posts: 419
Joined: May 11, 2004
 I'm really curious who has built this amplifier, how it sounds? Looks like it is very serious made amplifier.

Someone in my local area who has listened to this amplifier told me, this OTL is one of the best tube amplifier other than NYAL OTL-1 driving a pair of JBL horn speaker with zero impedance autoformer.

 

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RE: Alan Kimmel OTL, posted on March 1, 2012 at 23:47:04
6AS7_6SN7
 OTL + Autoformer = OT

IMHO, whatever the OTL be, it would be better to use high impedance speakers instead of autoformer-low impedance speakers.

In case of autoformer, it would be wise anyhow to have some means to switch out the autoformer in case of low power demand.

Best Regards
Luca

 

RE: Alan Kimmel OTL, posted on March 1, 2012 at 12:45:14
pickle
Audiophile

Posts: 306
Location: New York
Joined: May 21, 2002
 I have built a pair of Kimmel's amplifiers. What do you want to know?

 

RE: Alan Kimmel OTL, posted on January 6, 2014 at 12:30:14
sprussog
Audiophile

Posts: 7
Location: east germany by silicon saxony
Joined: October 23, 2013
 Hello,
for the Kimmel OTL I am very interested.
A simulation I made with LTspice.
At the 12AX7 tubes I have problems.
Up to the input of the 12AX7 everything is okay,
then the signal is broken.
Can anyone help me?

Best regards Steffen

 

RE: Alan Kimmel OTL, posted on January 18, 2014 at 19:48:28
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009



I've built the Kimmel OTL; it works nicely, and seems comparable to other OTLs I've built.

(Mine is a rather utilitarian construction, with no particular attempt at elegance!)

Chris

 

RE: Alan Kimmel OTL, posted on January 19, 2014 at 07:06:50
tyu
Audiophile

Posts: 963
Joined: April 19, 2011
 Vary nice...........what output tube is that...an are these 12AX7 inputs??.............if so looks like a lot of gain...have fun with tubes OTL...

 

RE: Alan Kimmel OTL, posted on January 19, 2014 at 09:12:04
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009
 Input is 12AU7. The output tubes are JJ EL509S.

I just made the "lite" version, with four output tubes per channel. I wanted to fit the whole stereo amp onto one chassis, rather than two monoblocks each with a separate power supply chassis as in Alan Kimmel's original article. It is a bit of a squeeze, and there's an outboard fan at the back, and the heater toroidal transformer too, like a spare tyre on an SUV.

Chris

 

RE: Alan Kimmel OTL, posted on January 19, 2014 at 13:12:20
tyu
Audiophile

Posts: 963
Joined: April 19, 2011
 what power output do you feel your geting?......i two like the stereo with the one ground for the two chn... it can sound sweeter to me.....i have diyed a Tron OTL like that...an ran all the tube hearters off one tranX...i like the sound alot....thanks for the info...

 

RE: Alan Kimmel OTL, posted on January 19, 2014 at 13:49:45
cpotl
Audiophile

Posts: 1002
Location: Texas
Joined: December 6, 2009
 tyu, I've never tried pushing it to the limits to measure the maximum output power it's capable of. In the original VTV article Alan Kimmel says the 8 tube version will give 210W rms into 8 ohms. There, he makes no mention of the output power with fewer output tubes. However, in another copy of the article I found on the internet, the specifications for a 6 tube and a 4 tube version are appended at the end. The claim there is 115W into 8 ohms for the 4 tube version. That sound somewhat high to me; roughly speaking, the maximum power should be limited by the current the output tubes can handle, and so with a halving of the number of tubes I'd have expected roughly one quarter of the power handling, not one half. My guess would be about 50W therefore, but as I say I've not felt inclined to push to the limits to measure it. I've measured up to about 25W rms into 8 ohms and stopped the experiment there.

Chris

 

RE: Alan Kimmel OTL, posted on January 20, 2014 at 06:11:10
tyu
Audiophile

Posts: 963
Joined: April 19, 2011
 I had a Melos two ch tube amp in the 90s......that had 4 EL509 in it ...the older tubes..... one with the plate on top....i still have some of the tubes here now i was going to put in a push-pull amp....only 4-5 of tubes....but i could never get the Melos amp setup.....how the hell can you get 200 watts out of two tubes
i sold the amp.... never sounded good.....but it had trodels output trax....at that time i was told the output trax were the prob....

But your amp may sound sweeter.....than the one with more EL504s
an less heat..........thats my prob....even the M60s i have to HOT..
i live with push pull amps an get great sound 50-60 wattes KT88s 6550s
an some mods....like the DC clamp on the output tubes that Bob Carvers uses in his amps....with a 5AL5 tube....i now have the tube amp sound i have been looking for for 40 year.... thanks for your time.

 

RE: Alan Kimmel OTL, posted on December 19, 2011 at 06:33:39
tyu
Audiophile

Posts: 963
Joined: April 19, 2011
 Look at these two amps.... i like the 6SN7 sound an the 6AS7...an the 6AS7 is at a fair $$...I dont care for the Sound of the EL509,or any pentoad in a OTL....and or the 12AX7 an i new a guy that diyed this amp an he an i like the circlotron sound better...Dose any one no the price of the 509...the one with the cap on top...not the new ones..Can you Still get this tube...thanks
All Just one mans o-pine





Well









 

RE: Alan Kimmel OTL, posted on March 1, 2012 at 23:50:02
6AS7_6SN7
 This is the very reason why of my moniker...

 

RE: Alan Kimmel OTL, posted on March 2, 2012 at 10:54:06
tyu
Audiophile

Posts: 963
Joined: April 19, 2011
 I got into Diying tube amps about 30 years ago....i went to the 6SN7 frist..my frends siad i was nuts ....min tubs have no place i see... less you have no heater V.... i wont a real tube sound ....but look how long it tuck alto catchup...now there the tube to have in any tubeampsetup...but...you no this..an so dose Ralph...6SN7.sweet tube sound....now as for the 6AS7 not till i got the M60s...i like the 6AS7 as a pr Driver...like preamp...Man thay can be vary tubbby..lot of fun ...can wate to see the frist pre that use the 6AS7 as a driver...Ralph had one of his prs runing the 6AS7 as a driver...mybe he well agin?? that was wayyyyyyyyyyyyy ahead of it time....that why hes the OTL King....Lew knows too...but he into the 12SN7 i think..but hes a moder ..so who no.

 

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