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09-04-2024, 11:55 AM
Hi Guys
Uzerman, I would say you should review the LP-PRE and PA66 product descriptions more carefully, and maybe look at "About Our Kits".
LP-PRE includes all the components that comprises the audio path, including: Rs, Cs, pots, jacks, tube sockets, PCB to carry main circuitry, small PCBs for each pot and jack.
PA66 includes all of the same, as well as bias test jacks and individual bias pots per tube onboard.
Your suggestion of needing a DPDT switch for channel switching assumes one would do the switching incorrectly, i.e. sending audio through the switch even if it is remote. We don't do that. Since there is a requirement for remote switching, we use remote-controllable muting/switching elements placed where the audio already is, then control those elements using DC voltages that can then be themselves controlled however is appropriate. In our own products, even if remote switching were not fitted, the audio control would be handled the same way to maintain short signal paths and reduce possible noise intrusion.
BFX switching can be easily handled using a new kit called BFX-RLY, which has two relays mounted on a small PCB, allowing proper on/off and series/mix functions.
Note that LP-PRE has dedicated wire blocks for the muting element connections. Typically LP-PRE is mated with ERK, which uses shunt switching via jfets. You definitely would NOT use 2N5457 as a muting element as its Rds-on is way too high.; it is fine in the audio path as a buffer or gain stage.
Note that the input impedance of LP-PRE is high and there is no need for any other buffering unless you wish to add a Thru jack to link inputs of other preamps/amps/tuner to the input jack.
Regarding the triode-pentode switch: Historically we used the C&K 7000-series for all switching in our amps as the specs allow for use as T/P and even mains, for the latter depending on the power of the amp. STUDIO has T-U-P switching, which offers ultra-linear in addition to triode and pentode modes. Jim, considering your amp history, you need the U option. C&K 7211 allows wiring as a 3-way switch and accommodates one tube, or bank of tubes - 'push' or 'pull' side. The C&Ks are a bit pricey and you can get identical switches from Carling for about 2/3 the price.
I forgot to mention in my previous post that PSU-50 has a proper raw bias supply so RBX is not required. This assumes you use our PT or a combination of PTs to take advantage of the PSU PCB.
Have fun
Uzerman, I would say you should review the LP-PRE and PA66 product descriptions more carefully, and maybe look at "About Our Kits".
LP-PRE includes all the components that comprises the audio path, including: Rs, Cs, pots, jacks, tube sockets, PCB to carry main circuitry, small PCBs for each pot and jack.
PA66 includes all of the same, as well as bias test jacks and individual bias pots per tube onboard.
Your suggestion of needing a DPDT switch for channel switching assumes one would do the switching incorrectly, i.e. sending audio through the switch even if it is remote. We don't do that. Since there is a requirement for remote switching, we use remote-controllable muting/switching elements placed where the audio already is, then control those elements using DC voltages that can then be themselves controlled however is appropriate. In our own products, even if remote switching were not fitted, the audio control would be handled the same way to maintain short signal paths and reduce possible noise intrusion.
BFX switching can be easily handled using a new kit called BFX-RLY, which has two relays mounted on a small PCB, allowing proper on/off and series/mix functions.
Note that LP-PRE has dedicated wire blocks for the muting element connections. Typically LP-PRE is mated with ERK, which uses shunt switching via jfets. You definitely would NOT use 2N5457 as a muting element as its Rds-on is way too high.; it is fine in the audio path as a buffer or gain stage.
Note that the input impedance of LP-PRE is high and there is no need for any other buffering unless you wish to add a Thru jack to link inputs of other preamps/amps/tuner to the input jack.
Regarding the triode-pentode switch: Historically we used the C&K 7000-series for all switching in our amps as the specs allow for use as T/P and even mains, for the latter depending on the power of the amp. STUDIO has T-U-P switching, which offers ultra-linear in addition to triode and pentode modes. Jim, considering your amp history, you need the U option. C&K 7211 allows wiring as a 3-way switch and accommodates one tube, or bank of tubes - 'push' or 'pull' side. The C&Ks are a bit pricey and you can get identical switches from Carling for about 2/3 the price.
I forgot to mention in my previous post that PSU-50 has a proper raw bias supply so RBX is not required. This assumes you use our PT or a combination of PTs to take advantage of the PSU PCB.
Have fun
