Stupid question from a tube amp newbie...

[DirkP]

I plan to buy my first tube amp tomorrow (the Blackstar HT1R head). I start with 1 watt! Will use it mostly with my only guitar (I swear I only have one), but will try micing it with my basses anyway...
Here is the question:

I know that this head needs to see a speaker load (great feature of the Ampeg PF-20 and PF-50 that they don't need one).
I have a Rupert Neve DI that can be switched from normal intrument level to speaker level, which means you can connect the speaker out from an amp directly to the DI.
But if I connect the speaker out from the amp to the "speaker in" from the DI, does the amp behaves as if a speaker is connected or does it feel betrayed and gets damaged?
I guess I shouldn't do this, am I right?

Second question (I'm pretty sure it works): I have a Pleasureboard from TecAmp. This is the same device as the so called "ass-shakers" for drummers etc. Essentially it is a motor, but a speaker in a way is a motor, too. I guess in this case the amp would behave as if a "real" speaker is connected and doesn't get damaged. Correct?

Thanx in Advance!

 

[Wasnex]

I plan to buy my first tube amp tomorrow (the Blackstar HT1R head). I start with 1 watt! Will use it mostly with my only guitar (I swear I only have one), but will try micing it with my basses anyway...
Here is the question:

I know that this head needs to see a speaker load (great feature of the Ampeg PF-20 and PF-50 that they don't need one).
I have a Rupert Neve DI that can be switched from normal intrument level to speaker level, which means you can connect the speaker out from an amp directly to the DI.
But if I connect the speaker out from the amp to the "speaker in" from the DI, does the amp behaves as if a speaker is connected or does it feel betrayed and gets damaged?
I guess I shouldn't do this, am I right?

Second question (I'm pretty sure it works): I have a Pleasureboard from TecAmp. This is the same device as the so called "ass-shakers" for drummers etc. Essentially it is a motor, but a speaker in a way is a motor, too. I guess in this case the amp would behave as if a "real" speaker is connected and doesn't get damaged. Correct?

Thanx in Advance!

A speaker level DI does not provide a load for a tube amp. You need the DI and a speaker or loadbox.

I believe the Pleasureboard has a nominal impedance of 8 ohms. I believe it uses dynamic voice coils like a speaker, but I don't know how closely the impedance curve is to an actual speaker. I would suggest reaching out to TecAmp (or possibly Eich) and asking if the Pleasureboard will work with a tube amp.

 

[DirkP]

I bought the amp today and a small 1x8 Vox speaker. For guitar this small amp is incredible. Works well for my Fender VI too. For bass the speaker and the 1 Watt amp - what a surprise - doesn't do to well. I connected a bass speaker for fun: one of my favourites, a Yamaha BBS110. I wasn't convinced either. Maybe I find a combination that works but 1 Watt might simply not be enough for bass and the preamp is guitar centic... But for guitar: just WOW! At low volumes it sounds better than a 100 Watt tube monster at low volume. And it really gets the entire palette from Fender to Marshall.

But I would really like to hear an answer from someone who really knows tube amps about that "speaker-load" issue.
I didn't try it without a real speaker or tried to just connect my Pleasureboard It clearly says on the back that a speaker has to be connected to the amp before switching it on. But - to my surprise - if I connect a cable to the headphone/speaker emulator output, it switches the speaker off. Does this mean that connecting a cable to the output deactivates the power amp? But the gain and the master still work in this position. Where is the speaker load gone when connecting a headphone and why doesn't this damage the amp?

I hope Blackstar does something similar for bass. I would buy it immediately.

It is this small head I bought:

 

[JimmyM]

I bought the amp today and a small 1x8 Vox speaker. For guitar this small amp is incredible. Works well for my Fender VI too. For bass the speaker and the 1 Watt amp - what a surprise - doesn't do to well. I connected a bass speaker for fun: one of my favourites, a Yamaha BBS110. I wasn't convinced either. Maybe I find a combination that works but 1 Watt simply isn't enough for bass and the preamp is guitar centic... But for guitar: jsut WOW!

But I would really like to hear an answer from someone who really knows tube amps about that "speaker-load" issue.
I didn't try it without a real speaker or tried to just connect my Pleasureboard It clearly says on the back that a speaker has to be connected to the amp before switching it on. But - to my surprise - if I connect a cable to the headphone/speaker emulator output, it switches the speaker off. Does this mean that connecting a cable to the output deactivates the power amp? But the gain and the master still work in this position. Where is the speaker load gone when connecting a headphone and why doesn't this damage the amp?

I imagine it has to be running preamp only with headphones in or using a dummy load. And since they say don't use it without a speaker load, I have to think it runs preamp only at that point. Using deductive reasoning, that has to be the answer. No reason they couldn't use a dummy load for it, but who knows? Might have jacked up the price another Euro

 

[Wasnex]

But I would really like to hear an answer from someone who really knows tube amps about that "speaker-load" issue.

IMHO, Anyone who gives you generic advice without knowing the impedance curve of the Pleasureboard is giving bad advice.

As I suggested earlier, your best bet is to contact the maker of the Pleasureboard and ask if it is compatible with tube amps. If they don't have an aswer, ask if they can provide a graph of the Pleasureboard's impedance.

 

[DirkP]

IMHO, Anyone who gives you generic advice without knowing the impedance curve of the Pleasureboard is giving bad advice.

As I suggested earlier, your best bet is to contact the maker of the Pleasureboard and ask if it is compatible with tube amps. If they don't have an aswer, ask if they can provide a graph of the Pleasureboard's impedance.

Thank you for your reply. I wouldn't connect my Pleasureboard to it, it needs more power than 1 watt anyway. I would just like to know what the issue is with the speaker-load.

 

[Wasnex]

Thank you for your reply. I wouldn't connect my Pleasureboard to it, it needs more power than 1 watt anyway. I would just like to know what the issue is with the speaker-load.

It not really a matter of how much power the Pleasureboard needs, given your goal. Providing the impedance is acceptable, the Pleasureboard would work fine as a dummy load, so you could safely run the amp with a speaker level DI and the Pleasureboard. Obviously 1W is not going to make the Pleasureboard vibrate very much though.

The deal with impedance is tube amps expect a certain load. The output transformer is a load matching device that matches the relatively high impedance of the tubes with the relatively low impedance of the speaker. Some amps have one output tap and some have multiple output taps.

When the amp sees the expected load, it operates properly and makes maximum power. When an impedance mismatch is created, the amp makes less power, experiences accelerated tube wear, and may malfunction catastrophically if it is not designed for an impedance mismatch. The impedance mismatch also tends to affect the tone and feel of the amp. Some amps tolerate a minor impedance mismatch fairly well (as much as 1:2 or 2:1), but it varies from amp to amp whether it's best for the mismatch to be on the high side or the low side. You should read the owners manual and/or contact the amp's maker if your interested in running an impedance mismatch...(see below).

At the extremes, a tube amp is safer running into a dead short than an open circuit...so always connect a load to your tube amp unless it is designed to run without a load.

FYI the owner's manual for this amp says the output is 4-16 ohms, and includes the warning, "Connect speaker before use." Most likely this means the output is 8 ohms and the amp is safe with a 1:2 or 2:1 impedance mismatch. For best results with bass, I suggest trying an 8 ohm load. It's possible the voicing and low frequency response are just too limited to sound good with bass though.

Invalid Link Removed

 

[Jim C]

To the OP
Listen to Wasnex on this.
I've spent time with various Ampeg tube amps, dummy loads, and DI out to the studio.
This was before reactive load boxes were readily available.

You can buy a purely resitive ballast resistor for testing.
based on pricing, I would get 4 Ohm and as many watts as you might need in the future.

OTOH, as mentioned above, if the two devices are compatible, you should go with it.
The down side of a mismatch is probably damaging the amp.

 

[Al Kraft]

First, a DI that can accept a speaker level signal is NOT a speaker load from the perspective of the amp. Second, I would never run any tube amp without a correctly matched (in Ohms) speaker connected, unless the amp manufacturer explicitly said it could be done and provided a specific procedure for so doing that.

While you can use dummy loads and other things to provide a tube amp's power section output the load it expects to run safely, you do need to know what you're doing - they are not necessarily one size fits all devices. If a tube power amp has a headphone out, I would assume that either it would automatically, or through some specific manufacturer procedure you'd follow, protect the power amp from "operating without a properly matched speaker load".

Calling the manufacturer for their advice and being able to be specific about the cabs, devices, etc. you want to use with their product is always a good idea in situation like this IME.

 

[CryingBass]

I plan to buy my first tube amp tomorrow (the Blackstar HT1R head). I start with 1 watt! Will use it mostly with my only guitar (I swear I only have one), but will try micing it with my basses anyway...
Here is the question:

I know that this head needs to see a speaker load (great feature of the Ampeg PF-20 and PF-50 that they don't need one).
I have a Rupert Neve DI that can be switched from normal intrument level to speaker level, which means you can connect the speaker out from an amp directly to the DI.
But if I connect the speaker out from the amp to the "speaker in" from the DI, does the amp behaves as if a speaker is connected or does it feel betrayed and gets damaged?
I guess I shouldn't do this, am I right?

Second question (I'm pretty sure it works): I have a Pleasureboard from TecAmp. This is the same device as the so called "ass-shakers" for drummers etc. Essentially it is a motor, but a speaker in a way is a motor, too. I guess in this case the amp would behave as if a "real" speaker is connected and doesn't get damaged. Correct?

Thanx in Advance!

Happy TubeDay. Really.

 

[Downunderwonder]

A 1w dummy load should be a no brainer to assemble, with a bit of advice on which resistor to use. It might cost 12 bucks for the bits and bobs for a ritzy one.