17 (+1) VINTAGE Genalex Gold Monarch KT88 Vacuum Tubes - SOLD
I thought I would run this here for a couple of days before moving to Audiogon (or possibly Ebay).
While I have these priced as a group, I am open to splitting them up for the right offer. I am also open to the possibility of partial trade offers, but the value has to be very, very good.
PLEASE MAKE SURE TO READ MY TERMS AND CONDITIONS (BELOW) BEFORE PURCHASE.Yes – these are ORIGINAL vintage Genalex Gold Monarch KT88 vacuum tubes. These are extremely desirable and very difficult to come by. I picked up a group of 22 of these, and am keeping 2 pairs for myself. 17 of the remaining 18 appear to be good and useable – the “+1” tube (tube #48) tests OK but has dropped one of the getters.
I do not know exactly where these came from, but the piece of the story I have is that they were used in piece of military equipment that involved a 5 KW lamp and over 100 pairs of these. My understanding is that these are the last ones from that group.
As you can see from the photos, these are clearly USED tubes, and are NOT pristine in any way, shape or form. The bases are generally weathered (but stable), and there is old tape residue and writing on all of the tubes. The printing is faded but still discernable. Flashing is good to excellent on most tubes (varies from tube to tube), but there clearly is some wear. Other than trying to get some of the tape off, and cleaning some of the pins a tiny bit, I have not modified these tubes in any way from the condition as received. I would at least recommend giving the pins a good cleaning prior to use.
As you will see below, all of these tubes test good to very good – NO test results are close to reject point. If you track these on Ebay, you will see that REJECT Gold Monarch KT88s are going for over $100 each. On that basis, my asking price seems pretty reasonable.
I have tested these tubes three ways:
(1) Weston 981 III – I tested these as 6550s using the comparable settings from a Heathkit TT-1 (KT88s are tested as 6550s on the Heathkit). The Weston does have its own setting for a 6550, but it does not make sense (tests at a plate voltage of 90V versus 225V for the Heathkit setting). The Weston and Heathkit are in many respects based on the same circuitry, and most of the octal settings for the Heathkit can be directly used on the Weston (and vice versa).
The reject point (65%) for this setting is 1430, making about 2200 “theoretical” 100%. In my general experience with the Weston, a new tube ON AVERAGE will test higher than this “theoretical” 100% level (say about 10%).
(2) Precision 660 emissions tester – These were once again tested as 6550s. Once again, the Precision does have its own setting for a KT88, but it does not make sense (tests at a filament voltage of 5V as opposed to 6.3V).
According to the Precision manual, an average new tube should read 84 (65+ is good). My experience is that this varies from tube to tube, so it is good to compare to a reference.
(3) A custom rig to measure plate current (Ia) – I used a custom rig to apply 250V plate voltage (Va) and -14 to -16 V grid voltage (Vg) to measure plate current (Ia) and derive transconductance (delta Ia/delta Vg) under these conditions. I am not entirely confident about the absolute numbers, but the numbers relative to one another and compared to the reference do provide useful information. The results are provided in the following format:
Ia (Vg = -14V)/Ia (Vg = -15V)/Ia (Vg = -16V)/derived Gm (mmhos)
All the results are provided below. On the Gold Monarchs, each tube has a number written on the top (from a previous owner). I will be using those numbers for identification in the results.
All tubes were clean for shorts and leakage.
I have also provided results for two lightly used new production KT88s (Shuguang) for comparison (not included).
Whether you use these results as absolute values or not is up to you, but the comparison (both against the Shuguang tubes and against one another) clearly seems to be of relevance.
Reference TubesShuguang KT88 #1
Weston 981 III 2450
Precision 660 95
Test Rig 121/132/144/11500
Shuguang KT88 #2
Weston 981 III 2300
Precision 660 96
Test Rig 112/123/134/11000
Gold Monarchs#8 Weston 981 III 1950
Precision 660 92
Test Rig 89/97/108/9500
#9 Weston 981 III 2000
Precision 660 92
Test Rig 94/104/114/10000
#13 Weston 981 III 1850
Precision 660 92
Test Rig 92/102/111/9500
#15 Weston 981 III 2000
Precision 660 94
Test Rig 99/109/118/9500
#21 Weston 981 III 1850
Precision 660 92
Test Rig 101/110/119/9000
#22 Weston 981 III 2000
Precision 660 92
Test Rig 95/105/114/9500
#23 Weston 981 III 1900
Precision 660 90
Test Rig 92/102/112/10000
#25 Weston 981 III 2050
Precision 660 92
Test Rig 110/120/130/10000
#28 Weston 981 III 2000
Precision 660 92
Test Rig 98/108/118/10000
#32 Weston 981 III 2150
Precision 660 94
Test Rig 107/118/127/10000
#34 Weston 981 III 2050
Precision 660 92
Test Rig 114/124/135/10500
#36 Weston 981 III 1875
Precision 660 92
Test Rig 94/102/110/8000
#38 Weston 981 III 1975
Precision 660 88
Test Rig 98/107/115/8500
#40 Weston 981 III 1900
Precision 660 90
Test Rig 93/101/109/8000
#44 Weston 981 III 1950
Precision 660 88
Test Rig 97/105/113/8000
#48 Weston 981 III 1900
Precision 660 90
Test Rig 95/103/112/8500
#49 Weston 981 III 2100
Precision 660 92
Test Rig 116/127/138/11000
#51 Weston 981 III 2000
Precision 660 90
Test Rig 102/111/122/10000
Based on these results, there should be a good number of pairs and even quads in this group. This is in fact an amazingly close testing group as a whole.
I can provide additional information or pictures upon request.
GENERAL TERMS AND CONDITIONS – PLEASE READ CAREFULLYPlease note that these tubes are being sold ‘AS IS’, but I will guarantee against a DOA tube (does not work at all). In such event, I will refund purchase price less shipping upon return of the tubes in the same condition as sent.
PLEASE NOTE THAT I CANNOT GUARANTEE (OR EVEN REMOTELY PREDICT) HOW THESE TUBES WILL SOUND OR PERFORM IN YOUR EQUIPMENT. THE TEST RESULTS ARE ONLY PROVIDED AS AN INDICATION OF TUBE PERFORMANCE IN A VERY LIMITED (AND NON-IDEAL) ENVIRONMENT. OTHER THAN AS SET FORTH ABOVE, I EXPRESSLY DISCLAIM ANY LIABILITY WITH RESPECT TO THESE TUBES OR RESPONSIBILITY FOR YOUR USE OF THEM.
Shipping in the USA via US Postal Priority Mail is included (I will likely ship in 2 boxes domestically). If you are outside the USA, or wish to use a different shipping method, contact me for a shipping quote.
Money order/cashiers check/personal check preferred, but all (other than US Postal money orders) must clear my bank first.
I also accept Paypal for convenience (but add 3% to the total for USA, and 4% to the total everywhere else).
IF YOU PAY VIA PAYPAL, HOWEVER, A CONDITION OF YOUR PAYMENT IS THAT YOU EXPRESSLY WAIVE THE RIGHT TO FILE A PAYPAL CLAIM OR CHARGE BACK (but do retain the right to sue me in court should you so desire).
IF YOU ARE NOT WILLING TO ACCEPT EACH AND EVERY ONE OF THE ABOVE TERMS AND CONDITIONS, DO NOT CONTACT ME AND DO NOT PURCHASE ANY OF THESE TUBES. NO EXCEPTIONS!Please check my feedback on Audiogon, Videogon and Ebay (ID=baileyler) and buy with confidence.
