Is anybody knows this tube preamp? Seem like a very good little preamp built around the 6922 tube. It is using quality parts ALPS pots, gold plated shorting RCA jack, WIMA caps.
And the price at 389U$ seems ok too.
Any other tube preamp not too expensive can be better?
Comments are welcome.
And the price at 389U$ seems ok too.
Any other tube preamp not too expensive can be better?
Comments are welcome.
What do you mean?
I check the WAM and the circuitry seems rather simple to me. Is it a better desing because of the output transfo?
I would like to drive my Aleph30 with it. Will it do? I got 50K input impedance on the Aleph30.
Thanks...
I check the WAM and the circuitry seems rather simple to me. Is it a better desing because of the output transfo?
I would like to drive my Aleph30 with it. Will it do? I got 50K input impedance on the Aleph30.
Thanks...
Hi,
Don't read too much into it, it's just that I happen to know where they buy their valves.
Let's say that it wouldn't be too hard to find better quality jobs.
It has its advantages in view of a CD based system.
Sure.
Cheers,😉
Don't read too much into it, it's just that I happen to know where they buy their valves.
Let's say that it wouldn't be too hard to find better quality jobs.
It has its advantages in view of a CD based system.
Sure.
Cheers,😉
http://www.qkits.com/serv/qkits/velleman/pages/K8020.asp
$449 canadian .. about $100 cheaper than $389US 🙂
I don't know much about the 8020 kit, but I built the 8021 from Velleman.
Overall decent quality, although I did get cheap op-amps w/ the kit, so I swapped those out for some nicer ones. So I can only imagine that you won't get great quality tubes (as mentioned before), although I could be very wrong w/ that.
However, qkits has good tech support if anything goes wrong.
Also, as mentioned before (once again), the foreplay is a good alternative 🙂
$449 canadian .. about $100 cheaper than $389US 🙂
I don't know much about the 8020 kit, but I built the 8021 from Velleman.
Overall decent quality, although I did get cheap op-amps w/ the kit, so I swapped those out for some nicer ones. So I can only imagine that you won't get great quality tubes (as mentioned before), although I could be very wrong w/ that.
However, qkits has good tech support if anything goes wrong.
Also, as mentioned before (once again), the foreplay is a good alternative 🙂
Algar_emi said:
"cheap" crap;
I have somewhere schmtc
better is to use any WOT based preamp,if ya need it to drive Pass amp.
tip-look for xformers from Vert. section of old BW tube TV sets,if ya need cheap solution for testing that concept.
Choky,
In the west, we haven't used vertical output transformers in TV's for 38 years (32 years some Japanese imports).
Maybe some could be thrown over the wall 😉 (ex wall).
And yes, I remember the ratio. It gave about 30 volts secondary, when 240 was on the primary.
Cheers,
In the west, we haven't used vertical output transformers in TV's for 38 years (32 years some Japanese imports).
Maybe some could be thrown over the wall 😉 (ex wall).
And yes, I remember the ratio. It gave about 30 volts secondary, when 240 was on the primary.
Cheers,
hehe-good one 😉dhaen said:
also,we (in the east) haven't used those xformers for few decades; but it's good to know old geezers ,with lotsa junk in backyards and attics
Valve Changes,Mods etc ?
That sounds encouraging as I brought one pre assembled used - so what valves would you recommend/mods or changes ?
Board diagram below >
PS: I know this thread hasn't been used for a bit but hopefully there will still be some Velleman owners still tweaking out there ?
That sounds encouraging as I brought one pre assembled used - so what valves would you recommend/mods or changes ?
Board diagram below >
PS: I know this thread hasn't been used for a bit but hopefully there will still be some Velleman owners still tweaking out there ?
Attachments
Last edited:
I reworked it according to the Conrad Johnson PV10A circuit diagram, as it is based on 12AU7 also. There are following changes:
R18-82k/2W
R13-3k3
R17-jumper wire
R14-jumper wire
R12-jumper wire
C18-jumper wire
C17-jumper wire
R16-jumper wire
R10-silicon diode, cathode to R11
R11-47k/2W
C21- 0,47u/400V at least, best you can buy
R15- 220k
The tubes - I suggest 12AU7 RCA clear top.
R18-82k/2W
R13-3k3
R17-jumper wire
R14-jumper wire
R12-jumper wire
C18-jumper wire
C17-jumper wire
R16-jumper wire
R10-silicon diode, cathode to R11
R11-47k/2W
C21- 0,47u/400V at least, best you can buy
R15- 220k
The tubes - I suggest 12AU7 RCA clear top.
Hey, I know this thread is ancient, but I'm looking at getting one of these preamps. Are these the only mods needed to make this thing sing?