Dedicated to HH Scott Vintage Vacuum Tube (or “Valve”) audio equipment.
*Safety Third! 🙂
Consider this the usual “people safety” disclaimers: High voltage is very dangerous, I’m not liable for you or your gear or anything, this is just advice, etc. There’s lots of information on high voltage safety on the net; find it, read it, understand it, practice it.
*An “in-joke” I won’t explain. Look it up.
There is also the unit’s safety to consider. Many of the key parts are no longer available, so don’t melt or smoke your amp! And be extra careful with the knobs and faceplates!
A few HH Scotts from my collection:
Some of my HH Scott amps and tuners
The 350’s faceplate (lower right) is not bent, just weird lighting!
Community and More Info:
HH Scott Amps:
LK-150 amp: Scott LK-150 Amp (and rebuild notes)
LC-21 preamp: Scott LC-21 Preamp ( and rebuild notes)
HH Scott tube amps – Setting the bias
I wrote a “white paper” on the theory and the practical aspects of setting output idle current (bias) via a negative bias voltage. Applicable broadly, but specific to Scotts.
Download it here: bias-notes.pdf
Here’s a handy chart for HH Scott amplifier power transformers, output tube types transformers, and the idle current settings (i.e. “bias”). Observe some amps can only set the idle current as a pair, as they expect the use of “plate current matched” output tubes. (I often modify these units to a per tube bias control, which then allows use of slightly unmatched output tubes.)
Note: these are the factory settings for max power output! Given the expense and scarcity of good output tubes, I suggest about 10% less idle current to extend output tube life at the cost of a small bit of max power.
| H.H. Scott Model | Power xformer | Idle current in mA per tube/pair | Output Tube type | Output xformer | Rated WPC |
| 200-B/LK-30 | TR 12-12-1 | 17.5 / 35 | 6GW8 | TRA 8-6 | 12 |
| 208 pwr amp | TR 13-3-2 | 35 / 70 | 7591 | TRA 11-2 | 32 / 36 |
| 222(A) | TR-12-7 | 6BQ5 | TRA 7-1 | 15 | |
| 222-B | TR 12-7? | 6BQ5 | TRA 7-1? | 15 | |
| 222-C | TR-12-3-2 | 22 / 44 | 7189/EL-84 | TRA 8-5-1 | 24 |
| 222-D | TR-12-13 | 22/44 | 7189/EL-84 | TRA-8-5-1 | 24 |
| 233 | TR-13-3-4 | 32.5 / 65 | 7591 | TRA 8-5-4 | 28 |
| 272 | TR-30-5 | 55 / 110 | 6CA7/EL-34 | TRA 12-2 | 37 |
| 290 | TR-30-4 | 55 / 110? | 6CA7/EL-34 | TRA 12-2 | 50 |
| 296 | TR-30-6 | 7581 | TRA 12-2-1 | 50 | |
| 299 (A) | TR-12-3-1 | 27.5 / 55 | 7189/EL-84 | TRA 8-4 | 21 |
| 299-B | TR-12-3-1 | 27.5 / 55 | 7189/EL-84 | TRA 8-5 | 21 |
| *299-C | TR-13-3 | 35 / 70 32.5 / 65 | 7591 | TRA 11-2 TRA-8-5-4 | 31 / 28 |
| 299-D | TR 13-3-2 | 35 / 70 | 7591 | TRA 11-2 | 34 |
| LK-48(A) | TR-12-3-1 | 22/44 | 7189/EL-84 | TRA 8-5-1 | 20 |
| LK-48-B | TR-12-13 | 22/44 | 7189/EL-84 | TRA 8-5-1 | 20 |
| LK-72(A) | TR 13-3 | 35 / 70 | 7591 | TRA 11-2 | 35 |
| LK-72-B | TR 13-3-2 | 35/70 | 7591 | TRA 11-2 | 35 |
| 340 (A) – rcvr | TR-15 | 32.5 / 65 | 7591 | TRA 8-6 | 27 |
| 340-B – rcvr | TR-15-2 | 35 / 70 | 7591 | TRA 8-5-3 | 30 |
| 345 – rcvr | TR-15-2 | 35 / 70 | 7591 | TRA 8-5-3 | 29 |
| 380 – rcvr | TR-15-2 | 35 / 70 | 7591 | TRA 8-5-3 | 32 |
| LK-150 pwr amp | TR-30-4-2 | 60/120 | 6550A/KT-88 | TRA 15-2 | 58 |
* – A significant production run change here. Later 299-C amps actually had 233 circuitry and the smaller TRA-8-5-4 transformers, so bias like a 233.
HH Scott Tuners
One of better general tuner reference sites: https://www.fmtunerinfo.com/tubetuners.html
This is my rambling, never quite completed, but still fairly useful Scott Tuner doc:
Downloadable PDF filet hhscott tuner alignment-97
It covers several decades of the tube tuners and contains a lot of practical experience in repairing, restoring, and aligning them. I did a cleanup pass in mid-2020, it’s at version 0.97 now.
A dedicated page to the Scott tube multplex unit: scott-fm-tube-multiplex-decoders/
Here’s a review project I did back in 2006 on an “audiophile modified” Scott 370 tuner.
(tl;dr: I was not impressed.) (This was intended to be the start of a review service, but about that time my full time job got very demanding and I never got back to it.)
Last Updated on 2026-02-18 by Daev Roehr