Glenn OTL Tube Compatibility

	A	B	C	D
1	Tube Function	Tube Type	Adapter Required	Notes

2	Rectifier	422A	Can work with or without adapter. Read notes...	Glenn: "The 422A is the best rectifier and will work without a adapter but will add 5 volts of 50 or 60 Hz to the power supply. Normally the power supply will filter this out but why add this in the first place if it can be eliminated by a adapter (that reverses pins 2 and 8)."
3	Rectifier	U52	N/A
4	Rectifier	53KU	N/A
5	Rectifier	GZ32	N/A
6	Rectifier	GZ33	N/A
7	Rectifier	GZ34 / 5AR4	N/A
8	Rectifier	GZ37	N/A
9	Rectifier	596	Yes
10	Rectifier	1641	Yes
11	Rectifier	5R4GY	N/A	Glenn: "The 5R4 has the highest voltage drop." People not impressed with RCA 5R4GY, but Philips, Brimar and Fivre are quite good.
12	Rectifier	5U4G	N/A	OK when running 6BX7 or 6BL7 (2, 4 or 6 tubes) but not other output tubes! (Source: Glenn on post # 27864)
13	Rectifier	5U4GB	N/A	"B" is important. This one does NOT have the limitations of 5U4G (see above)
14	Rectifier	3DG4	N/A
15	Rectifier	5CU4	N/A
16	Rectifier	AZ12	AZ12 to 3DG4 adapter from Deyan	gibosi: AZ12 max at 200ma, so not powerful enough to run GOTL with 6AS7 output tubes. Not powerful enough to run six 6BL7. Fine with four 6BL7.
17	C3g Driver	C3g	N/A
18	C3g Driver	EL8, EL3N, EL6	Deyan's custom adapters for EL3N to c3g
19	C3g Driver	EL32, 6J7	Deyan's custom adapters for EL32 to c3g
20	C3g Driver	EL11, EL12N, EL13	Deyan's custom adapters for EL11 to c3g
21	C3g Driver	EL41, EL42	EL42 to C3g adapters	@gibosi confirmed EL41 and EL42 tubes work with those adapters!
22	6.3 volt Driver	6SN7, 6SN7GT, 6SN7GTA, 6SN7GTB, 6SN7W, 6H8C, VT-231	N/A	Amplification factor of 20
23	6.3 volt Driver	6SL7, VT-229, 5691, 6H9C / 6N9S (Russian), 6N9P (Chinese)	N/A	Similar to the 6SN7 but with higher gain (amplification factor of 70)
24	6.3 volt Driver	ECC35 (British), 33S29 (Swedish), 6SU7GTY (premier 6SL7)	N/A	More 6SL7 variants...
25	6.3 volt Driver	ECC32, ECC33	N/A
26	6.3 volt Driver	6N7, 6N7G, 6N7GT, ECC31	ECC31 to 6SN7 adapter (from Deyan)
27	6.3 volt Driver	6Z7, 6Z7G	ECC31 to 6SN7 adapter (from Deyan)	Reported by @mordy in Aug. 2020 and approved by Glenn. According to mordy: "bass is very good .... the treble is on the bright side .... mid range is pretty good; BUT there is a rough edgy quality to the sound .... it simply lacks sweetness"
28	6.3 volt Driver	6A6	6A6 to 6SN7 adapter
29	6.3 volt Driver	EL3N	Dual EL3N to 6SN7
30	6.3 volt Driver	6DJ8, ECC88, 6922, E88CC, 7308, 6N23, ECC804, 6/30L2	ECC88 to 6SN7 adapter
31	6.3 volt Driver	6CG7, 6FQ7, 6BC8, 6BS8, 6BZ7, 6BQ7A, X155	ECC88 to 6SN7 adapter
32	6.3 volt Driver	6F8G / VT-99, 6C8G / VT-163	6F8G to 6SN7 adapter
33	6.3 volt Driver	76	76 to 6SN7 adapter
34	6.3 volt Driver	L63, 6J5, CV1932, 6C5G, 6P5	Dual 6J5 to 6SN7 adapter
35	6.3 volt Driver	5670, 2C51, 6385, 396A, 6N3P	5670 to 6SN7 adapter
36	6.3 volt Driver	5687, 7044, 7119, E182CC	5687 to 6SN7 adapter
37	6.3 volt Driver	7N7	7N7 to 6SN7 adapter	Loctal base version of 6SN7
38	6.3 volt Driver	7F7, VT-189, CV893	7N7 to 6SN7 adapter	Loctal base version of 6SL7GT (similar to the 7N7 but with higher gain)
39	6.3 volt Driver	6C4 / CV133 / 6100 / EC90	Dual 6C4 to 6SN7 adapter
40	6.3 & 12.6 volt Driver	12AU7, M8136, CV4003, E82CC, E180CC	12AU7 to 6SN7 (6v) or 12SN7 (12v) adapter	12AU7 & 12AT7 use same adapters. Operate at 6v or 12v (depending on adapter used).
41	6.3 & 12.6 volt Driver	12AT7, 12AZ7, 12BH7	12AT7 to 6SN7 (6v) or 12SN7 (12v) adapter	12AU7 & 12AT7 use same adapters. Operate at 6v or 12v (depending on adapter used).
42	12.6 volt Driver	B36	N/A
43	12.6 volt Driver	FDD20	FDD20 to 12SN7 adapter
44	12.6 volt Driver	12SN7, 12SL7GT, 12SX7	N/A	12v version of 6SN7
45	12.6 volt Driver	14N7, 14H7	7N7 to 6SN7 adapter	12v version of 7N7
46	12.6 volt Driver	12J5	Dual 12J5 to 12SN7 adapter	Glenn confirmed that it would work and sound great
47	25.2 volt Driver	13D1	N/A
48	25.2 volt Driver	1633	N/A
49	Power / Output	6AS7G, 6AS7GA, CV2523/A1834	N/A	Use 1 or 2 pairs
50	Power / Output	5998, 6520, 421A	N/A	Use 1 or 2 pairs
51	Power / Output	6080, 6080WB, CV2984	N/A	Use 1 or 2 pairs
52	Power / Output	6336B	N/A	Do not use more than 1 pair!!
53	Power / Output	7236	N/A	Use 1 or 2 pairs
54	Power / Output	6H13C, 6N13P, 6N5P, 6N5S	N/A	Use 1 or 2 pairs
55	Power / Output	6BX7GT	N/A	Use 2 or 3 pairs
56	Power / Output	6BL7GT, 6BL7GTA	N/A	Use 2 or 3 pairs
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58	NOT Compatible!!!	6L6GC (or the Russian equivalent 6N3C)	N/A	Listed to prevent repeated questions from newbies like me ;-)
59	NOT Compatible!!!	6V6	N/A	Compatible with GEL3N amp, but not for GOTL
60	NOT Compatible!!!	KT88	N/A	@UntilThen: "KT88 in the GOTL will be more lethal than 10 shots of Tequila"
61	NOT Compatible!!!	EL34 / 6CA7	N/A	Glenn: "They are single pentodes the OTL needs a dual triode."
62	NOT Recommended	12AX7	12AU7 to 6SN7 or 12SN7	Would work but amplification too high to be useful
63	NOT Recommended	7AF7, 14AF7		They work but turn microphonic or become noise.
64	NOT Recommended	7802 (look almost identical to 6080)	N/A	Glenn: "I do not recommend using the 7802 in this amp. They require a 500 ohm cathode resistor and the ones in the amp are 1/2 that so the tubes will be over current and get very hot and probably ruin them."
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