Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th September 2008, 05:03 PM   #1
jazzbo is offline jazzbo  Canada
diyAudio Member
 
jazzbo's Avatar
 
Join Date: May 2007
Default Hashimoto A-105 - summary so far

Here is the story so far. Tested are 45, 46, ECC99, 5687, 12BH7A, 6S4A, 6GK5, all normalized to 1kHz. I'll post later on operating points for each tube. Still to test are 6N1P and 6C45Pi. If you'd like to see anything else, let me know. Enjoy!
Attached Images
File Type: gif summary.gif (25.5 KB, 220 views)
  Reply With Quote
Old 24th September 2008, 05:46 PM   #2
kmaier is offline kmaier  United States
diyAudio Member
 
kmaier's Avatar
 
Join Date: Jul 2007
Thanks JB.... enlightening.

Have you tried putting a passive load on the secondary yet? Possibly a range from 20K to 100K (in increments) to see how this affects the output?

Regards, KM
  Reply With Quote
Old 24th September 2008, 08:03 PM   #3
jazzbo is offline jazzbo  Canada
diyAudio Member
 
jazzbo's Avatar
 
Join Date: May 2007
No, I haven't tried loading the secondary yet. I've pretty much decided on a 9 pin driver in a 2 stage amp, preferably a dual triode because I can use the other half as a shunt regulator (this was done on the 5687 and 12BH7A). I'll go back to the ECC99 and try different secondary loads as you suggest. I've read that loading the secondary results in higher transformer distortion. Anyone care to comment on this? Also, does anyone have any opinions/preferences among the ECC99, 5687, 6S4A and 12BH7A as drivers? I know JandG expressed a preference for the 12BH7A in his IT amp. Anyone else?

re 12BH7A: the one I tested is a GE made in Canada. I also tried japanese and korean tubes. Both exhibited lower bias for a given plate voltage and higher rp. Anyone tried the russian EHs, and if so, how do they compare? NOS 12BH7As are getting pricey...
  Reply With Quote
Old 24th September 2008, 09:31 PM   #4
kmaier is offline kmaier  United States
diyAudio Member
 
kmaier's Avatar
 
Join Date: Jul 2007
Hi JB,

Are you able to measure distortion via test equipment? I would suspect running zero load (sans the IT inductance) that the driver is not seeing a consistent load vs frequency. This is probably resulting in higher distortion as the driver is not always in the linear operating range.

From feedback from another user (I can't test mine yet... over 4000 miles distance from them) loading the secondary actually reduced distortion and response was better.

As for prices... yea, they keep going up. Mike at KCA has GE NOS for $30 and RCA NOS for $35... Surplus Sales has RCAs for $19. ESRC has RCAs for $16. You do have some choices... NOS RCAs would be my choice. I would also suggest trying a 6FQ7, these are essentially a 6SN7 in a smaller 9-pin.

Regards, KM
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hashimoto A-105 - 6S4A jazzbo Tubes / Valves 15 30th December 2012 11:21 AM
UcD400, in summary. ivigueras Class D 144 5th October 2011 12:14 AM
Hashimoto and the wonderful 45 kmaier Tubes / Valves 10 24th June 2008 02:46 PM
Hashimoto H-20-7U for 6v6 in triode SE..? JandG Tubes / Valves 1 9th June 2008 02:26 PM
ETF07 brief summary SY Tubes / Valves 15 8th December 2007 03:50 PM


New To Site? Need Help?

All times are GMT. The time now is 07:38 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2