Hi!
I am building a prototype of the amp, it will be monoblock, 200W output, 4xGU-50.
I have a dilemma, which side should be the face, with front panel?
Usually monoblocks have short face. But if to make the front panel on the long side it will be 19" rack mountable. Which road should I choose?
The front panel will contain only power switch and volume control. Rear panel will contain power socket, fuse, output binding posts, RCA and XLR sockets, RCA-XLR switch.
I am building a prototype of the amp, it will be monoblock, 200W output, 4xGU-50.
I have a dilemma, which side should be the face, with front panel?
Usually monoblocks have short face. But if to make the front panel on the long side it will be 19" rack mountable. Which road should I choose?
The front panel will contain only power switch and volume control. Rear panel will contain power socket, fuse, output binding posts, RCA and XLR sockets, RCA-XLR switch.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Joined 2009
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They will not be shielded, I just put sockets to see sizes. One will be cat's green eye.
If to make the face short It would be better to put input sockets on the front panel, but power switch on the rear one.
Sure, no problems. Everything will be in public domain with disclaimer, "800 Volts kills!"
May be I will sell PCBs, if somebody wants.
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Special order for power transformer. Output transformer is 4k2 for 100W from 20 Hz. From 40 Hz it will work nice for 200W, but I should try first. CXPP-100-MS-4.2K
So, I am curious. Will this be pentode operation of the ordinary sort, or incorporate some of your Schade magic? I suppose what I am asking is, Can you give some basic circuit description? I have read more than a couple of threads regarding the gu-50. I have noticed that you have put quite a bit of time into developing circuits with this valve and will follow this thread. GU-50...Wavebourn...these two are always found together, it seems.
Yes, it will be in pentode mode, with local feedbacks across output tubes. The difference from previous Pyramids, MOSFET followers to drive output tubes, and 2 tubes in parallel for twice higher power. However, the power will be rated for frequencies from 40 Hz, instead of 20 Hz, but it is plenty, since such amps either drive Magnepans at homes, or concert line arrays. For subs (frequencies below 40 Hz) I believe class D amps are better.
I would not suggest to remove all that "extra metal" from sockets: pins are thin, and key is on the glass, so it is easy to insert tubes wrongly damaging the amp.
I would not suggest to remove all that "extra metal" from sockets: pins are thin, and key is on the glass, so it is easy to insert tubes wrongly damaging the amp.
Below is a picture of my modified Cary SLM-100 with following changes:
1) Input on the front to have now signal trough the power & output and also a very short connection to the first input tube
2) Power switch on the back to avoid long power cables trough the chassis
3) the standby (connection to ground with a lift up resistor) switch & cables connection has been shorted and now use a relays.
Still open & research in progress (may some one helps in this regard
): the schematic for the real XLR / symmetric input while have only 2 * 6SN7 tubes... HpW
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Having faced the same dilemma recently, I can say that the only way that sensitive signals do not pass near the power supply AND not have the input jacks right on the front, is to have the long face forward. Then again, you can take a cue from Ming-Da preamps (yes, them), and have the narrow face front, but the inputs on the side forward.
Below is a picture of my modified Cary SLM-100 with following changes:
1) Input on the front to have now signal trough the power & output and also a very short connection to the first input tube
2) Power switch on the back to avoid long power cables trough the chassis
3) the standby (connection to ground with a lift up resistor) switch & cables connection has been shorted and now use a relays.
Still open & research in progress (may some one helps in this regard
HpW
makes a lot of sense to me, this is also my prefference, but you know there are folks that find this arrangement ungly no matter how i try to explain the advantages...oh well......
When I think in terms of MOSFET followers in this type of application, I think in terms of the TubeLab "power-drive" (because I am somewhat familiar with it). Whatever scheme specifics may be, such a follower concept does seem to open the doors to a very broad selection of drivers and also seems as if it should be "sonically invisible".
Two questions:
.......1) Is it sonically invisible?
and, 2) Are you contemplating a regulated screen supply?
It seems to me that screen supply regulation might represent the last link in a design of this basic description: dynamic maintenance of impedance, that is to say.
Two questions:
.......1) Is it sonically invisible?
and, 2) Are you contemplating a regulated screen supply?
It seems to me that screen supply regulation might represent the last link in a design of this basic description: dynamic maintenance of impedance, that is to say.
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Joined 2009
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Well, for this I have a common power plain (and power filter) with all audio stuff on and a single common power switch for all.
HpW
which side to front?
Hi Waveburn,
Wow, 4 GU50 that will give your amp the real grunt. For my taste, I would prefer it with the narrow side to front.
I made a test setup with 6 of the GU50. I drive them hard into grid current (B2) They drive 450W into the Load at 1000V plate and 250V g2 . What an amazing valve. My aim is to build a Bass Guitar amp with these.
73
Wolfgang
Hi Waveburn,
Wow, 4 GU50 that will give your amp the real grunt.
For my taste, I would prefer it with the narrow side to front.I made a test setup with 6 of the GU50. I drive them hard into grid current (B2) They drive 450W into the Load at 1000V plate and 250V g2 . What an amazing valve. My aim is to build a Bass Guitar amp with these.
73
Wolfgang
perfect timing
Yesterday I was -just one more time- thinking what to do with the two big PTs that I have laying around. Wavebournes posts got me interested in the GU-50, so I checked out their availability, prices, specs, compatibility with my PTs. I could do 4 or 6 per channel. When I woke up this morning I say this thread... Now that's what I call a good start of the day
I'll be following this one.
Yesterday I was -just one more time- thinking what to do with the two big PTs that I have laying around. Wavebournes posts got me interested in the GU-50, so I checked out their availability, prices, specs, compatibility with my PTs. I could do 4 or 6 per channel. When I woke up this morning I say this thread... Now that's what I call a good start of the day
I'll be following this one.
Although I voted long front ...this 500W amp is 19"x18" square ...snags, no room available at the rear for AC socket and opposite side XLR inputs, for listening room and stage aesthesics I avoided front panel clutter as rt'angled entry of both IEC and XLR are around.
I'd admit getting the mechanical size of this amp into a 19" rack criteria wasn't easy.
richy
I'd admit getting the mechanical size of this amp into a 19" rack criteria wasn't easy.
richy
